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# Line 98  SECURITY CONSIDERATIONS Line 98  SECURITY CONSIDERATIONS
98         supply arbitrary patterns for compilation, you should  be  aware  of  a         supply arbitrary patterns for compilation, you should  be  aware  of  a
99         feature that allows users to turn on UTF support from within a pattern,         feature that allows users to turn on UTF support from within a pattern,
100         provided that PCRE was built with UTF support. For  example,  an  8-bit         provided that PCRE was built with UTF support. For  example,  an  8-bit
101         pattern  that  begins  with  "(*UTF8)" turns on UTF-8 mode. This causes         pattern  that  begins  with  "(*UTF8)" or "(*UTF)" turns on UTF-8 mode,
102         both the pattern and any data against which it is matched to be checked         which interprets patterns and subjects as strings of  UTF-8  characters
103         for UTF-8 validity. If the data string is very long, such a check might         instead  of  individual 8-bit characters.  This causes both the pattern
104         use sufficiently many resources as to cause your  application  to  lose         and any data against which it is matched to be checked for UTF-8 valid-
105         performance.         ity.  If  the  data  string is very long, such a check might use suffi-
106           ciently many resources as to cause your  application  to  lose  perfor-
107           mance.
108    
109         The  best  way  of  guarding  against  this  possibility  is to use the         The  best  way  of  guarding  against  this  possibility  is to use the
110         pcre_fullinfo() function to check the compiled  pattern's  options  for         pcre_fullinfo() function to check the compiled  pattern's  options  for
# Line 172  AUTHOR Line 174  AUTHOR
174    
175  REVISION  REVISION
176    
177         Last updated: 30 October 2012         Last updated: 11 November 2012
178         Copyright (c) 1997-2012 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
179  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
180    
181    
182  PCRE(3)                                                                PCRE(3)  PCRE(3)                                                                PCRE(3)
183    
184    
# Line 315  THE PCRE 16-BIT LIBRARY Line 317  THE PCRE 16-BIT LIBRARY
317  THE HEADER FILE  THE HEADER FILE
318    
319         There is only one header file, pcre.h. It contains prototypes  for  all         There is only one header file, pcre.h. It contains prototypes  for  all
320         the  functions  in  both  libraries,  as  well as definitions of flags,         the functions in all libraries, as well as definitions of flags, struc-
321         structures, error codes, etc.         tures, error codes, etc.
322    
323    
324  THE LIBRARY NAME  THE LIBRARY NAME
# Line 334  STRING TYPES Line 336  STRING TYPES
336         PCRE_UCHAR16  specifies  an  appropriate  data type, and PCRE_SPTR16 is         PCRE_UCHAR16  specifies  an  appropriate  data type, and PCRE_SPTR16 is
337         defined as "const PCRE_UCHAR16 *". In very  many  environments,  "short         defined as "const PCRE_UCHAR16 *". In very  many  environments,  "short
338         int" is a 16-bit data type. When PCRE is built, it defines PCRE_UCHAR16         int" is a 16-bit data type. When PCRE is built, it defines PCRE_UCHAR16
339         as "short int", but checks that it really is a 16-bit data type. If  it         as "unsigned short int", but checks that it really  is  a  16-bit  data
340         is not, the build fails with an error message telling the maintainer to         type.  If  it is not, the build fails with an error message telling the
341         modify the definition appropriately.         maintainer to modify the definition appropriately.
342    
343    
344  STRUCTURE TYPES  STRUCTURE TYPES
# Line 501  AUTHOR Line 503  AUTHOR
503    
504  REVISION  REVISION
505    
506         Last updated: 14 April 2012         Last updated: 08 November 2012
507         Copyright (c) 1997-2012 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
508  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
509    
510    
511  PCRE(3)                                                                PCRE(3)  PCRE(3)                                                                PCRE(3)
512    
513    
# Line 644  THE PCRE 32-BIT LIBRARY Line 646  THE PCRE 32-BIT LIBRARY
646  THE HEADER FILE  THE HEADER FILE
647    
648         There is only one header file, pcre.h. It contains prototypes  for  all         There is only one header file, pcre.h. It contains prototypes  for  all
649         the  functions  in  both  libraries,  as  well as definitions of flags,         the functions in all libraries, as well as definitions of flags, struc-
650         structures, error codes, etc.         tures, error codes, etc.
651    
652    
653  THE LIBRARY NAME  THE LIBRARY NAME
# Line 827  AUTHOR Line 829  AUTHOR
829    
830  REVISION  REVISION
831    
832         Last updated: 24 June 2012         Last updated: 08 November 2012
833         Copyright (c) 1997-2012 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
834  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
835    
836    
837  PCREBUILD(3)                                                      PCREBUILD(3)  PCREBUILD(3)                                                      PCREBUILD(3)
838    
839    
# Line 1320  REVISION Line 1322  REVISION
1322         Last updated: 30 October 2012         Last updated: 30 October 2012
1323         Copyright (c) 1997-2012 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
1324  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
1325    
1326    
1327  PCREMATCHING(3)                                                PCREMATCHING(3)  PCREMATCHING(3)                                                PCREMATCHING(3)
1328    
1329    
# Line 1529  REVISION Line 1531  REVISION
1531         Last updated: 08 January 2012         Last updated: 08 January 2012
1532         Copyright (c) 1997-2012 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
1533  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
1534    
1535    
1536  PCREAPI(3)                                                          PCREAPI(3)  PCREAPI(3)                                                          PCREAPI(3)
1537    
1538    
# Line 1642  PCRE NATIVE API INDIRECTED FUNCTIONS Line 1644  PCRE NATIVE API INDIRECTED FUNCTIONS
1644         int (*pcre_callout)(pcre_callout_block *);         int (*pcre_callout)(pcre_callout_block *);
1645    
1646    
1647  PCRE 8-BIT, 16-BIT AND 32-BIT LIBRARIES  PCRE 8-BIT, 16-BIT, AND 32-BIT LIBRARIES
1648    
1649         From  release  8.30,  PCRE  can  be  compiled as a library for handling         As  well  as  support  for  8-bit character strings, PCRE also supports
1650         16-bit character strings as  well  as,  or  instead  of,  the  original         16-bit strings (from release 8.30) and  32-bit  strings  (from  release
1651         library  that  handles 8-bit character strings. From release 8.32, PCRE         8.32),  by means of two additional libraries. They can be built as well
1652         can also be  compiled  as  a  library  for  handling  32-bit  character         as, or instead of, the 8-bit library. To avoid too  much  complication,
1653         strings.  To  avoid  too much complication, this document describes the         this  document describes the 8-bit versions of the functions, with only
1654         8-bit versions of the functions, with only occasional references to the         occasional references to the 16-bit and 32-bit libraries.
1655         16-bit and 32-bit libraries.  
1656           The 16-bit and 32-bit functions operate in the same way as their  8-bit
1657         The  16-bit and 32-bit functions operate in the same way as their 8-bit         counterparts;  they  just  use different data types for their arguments
1658         counterparts; they just use different data types  for  their  arguments         and results, and their names start with pcre16_ or pcre32_  instead  of
1659         and  results,  and their names start with pcre16_ or pcre32_ instead of         pcre_.  For  every  option  that  has  UTF8  in  its name (for example,
1660         pcre_. For every option  that  has  UTF8  in  its  name  (for  example,         PCRE_UTF8), there are corresponding 16-bit and 32-bit names  with  UTF8
        PCRE_UTF8),  there  are corresponding 16-bit and 32-bit names with UTF8  
1661         replaced by UTF16 or UTF32, respectively. This facility is in fact just         replaced by UTF16 or UTF32, respectively. This facility is in fact just
1662         cosmetic;  the  16-bit and 32-bit option names define the same bit val-         cosmetic; the 16-bit and 32-bit option names define the same  bit  val-
1663         ues.         ues.
1664    
1665         References to bytes and UTF-8 in this document should be read as refer-         References to bytes and UTF-8 in this document should be read as refer-
1666         ences  to  16-bit  data  quantities  and  UTF-16  when using the 16-bit         ences to 16-bit data  quantities  and  UTF-16  when  using  the  16-bit
1667         library, or 32-bit data quantities and UTF-32  when  using  the  32-bit         library,  or  32-bit  data  quantities and UTF-32 when using the 32-bit
1668         library,  unless specified otherwise. More details of the specific dif-         library, unless specified otherwise. More details of the specific  dif-
1669         ferences for the 16-bit and 32-bit libraries are given  in  the  pcre16         ferences  for  the  16-bit and 32-bit libraries are given in the pcre16
1670         and pcre32 pages.         and pcre32 pages.
1671    
1672    
1673  PCRE API OVERVIEW  PCRE API OVERVIEW
1674    
1675         PCRE has its own native API, which is described in this document. There         PCRE has its own native API, which is described in this document. There
1676         are also some wrapper functions (for the 8-bit library only) that  cor-         are  also some wrapper functions (for the 8-bit library only) that cor-
1677         respond  to  the  POSIX  regular  expression  API, but they do not give         respond to the POSIX regular expression  API,  but  they  do  not  give
1678         access to all the functionality. They are described  in  the  pcreposix         access  to  all  the functionality. They are described in the pcreposix
1679         documentation.  Both  of these APIs define a set of C function calls. A         documentation. Both of these APIs define a set of C function  calls.  A
1680         C++ wrapper (again for the 8-bit library only) is also distributed with         C++ wrapper (again for the 8-bit library only) is also distributed with
1681         PCRE. It is documented in the pcrecpp page.         PCRE. It is documented in the pcrecpp page.
1682    
1683         The  native  API  C  function prototypes are defined in the header file         The native API C function prototypes are defined  in  the  header  file
1684         pcre.h, and on Unix-like systems the (8-bit) library itself  is  called         pcre.h,  and  on Unix-like systems the (8-bit) library itself is called
1685         libpcre.  It  can  normally be accessed by adding -lpcre to the command         libpcre. It can normally be accessed by adding -lpcre  to  the  command
1686         for linking an application that uses PCRE. The header file defines  the         for  linking an application that uses PCRE. The header file defines the
1687         macros PCRE_MAJOR and PCRE_MINOR to contain the major and minor release         macros PCRE_MAJOR and PCRE_MINOR to contain the major and minor release
1688         numbers for the library. Applications can use these to include  support         numbers  for the library. Applications can use these to include support
1689         for different releases of PCRE.         for different releases of PCRE.
1690    
1691         In a Windows environment, if you want to statically link an application         In a Windows environment, if you want to statically link an application
1692         program against a non-dll pcre.a  file,  you  must  define  PCRE_STATIC         program  against  a  non-dll  pcre.a  file, you must define PCRE_STATIC
1693         before  including  pcre.h or pcrecpp.h, because otherwise the pcre_mal-         before including pcre.h or pcrecpp.h, because otherwise  the  pcre_mal-
1694         loc()   and   pcre_free()   exported   functions   will   be   declared         loc()   and   pcre_free()   exported   functions   will   be   declared
1695         __declspec(dllimport), with unwanted results.         __declspec(dllimport), with unwanted results.
1696    
1697         The   functions   pcre_compile(),  pcre_compile2(),  pcre_study(),  and         The  functions  pcre_compile(),  pcre_compile2(),   pcre_study(),   and
1698         pcre_exec() are used for compiling and matching regular expressions  in         pcre_exec()  are used for compiling and matching regular expressions in
1699         a  Perl-compatible  manner. A sample program that demonstrates the sim-         a Perl-compatible manner. A sample program that demonstrates  the  sim-
1700         plest way of using them is provided in the file  called  pcredemo.c  in         plest  way  of  using them is provided in the file called pcredemo.c in
1701         the PCRE source distribution. A listing of this program is given in the         the PCRE source distribution. A listing of this program is given in the
1702         pcredemo documentation, and the pcresample documentation describes  how         pcredemo  documentation, and the pcresample documentation describes how
1703         to compile and run it.         to compile and run it.
1704    
1705         Just-in-time  compiler  support is an optional feature of PCRE that can         Just-in-time compiler support is an optional feature of PCRE  that  can
1706         be built in appropriate hardware environments. It greatly speeds up the         be built in appropriate hardware environments. It greatly speeds up the
1707         matching  performance  of  many  patterns.  Simple  programs can easily         matching performance of  many  patterns.  Simple  programs  can  easily
1708         request that it be used if available, by  setting  an  option  that  is         request  that  it  be  used  if available, by setting an option that is
1709         ignored  when  it is not relevant. More complicated programs might need         ignored when it is not relevant. More complicated programs  might  need
1710         to    make    use    of    the    functions     pcre_jit_stack_alloc(),         to     make    use    of    the    functions    pcre_jit_stack_alloc(),
1711         pcre_jit_stack_free(),  and pcre_assign_jit_stack() in order to control         pcre_jit_stack_free(), and pcre_assign_jit_stack() in order to  control
1712         the JIT code's memory usage.         the JIT code's memory usage.
1713    
1714         From release 8.32 there is also a direct interface for  JIT  execution,         From  release  8.32 there is also a direct interface for JIT execution,
1715         which  gives  improved performance. The JIT-specific functions are dis-         which gives improved performance. The JIT-specific functions  are  dis-
1716         cussed in the pcrejit documentation.         cussed in the pcrejit documentation.
1717    
1718         A second matching function, pcre_dfa_exec(), which is not Perl-compati-         A second matching function, pcre_dfa_exec(), which is not Perl-compati-
1719         ble,  is  also provided. This uses a different algorithm for the match-         ble, is also provided. This uses a different algorithm for  the  match-
1720         ing. The alternative algorithm finds all possible matches (at  a  given         ing.  The  alternative algorithm finds all possible matches (at a given
1721         point  in  the  subject), and scans the subject just once (unless there         point in the subject), and scans the subject just  once  (unless  there
1722         are lookbehind assertions). However, this  algorithm  does  not  return         are  lookbehind  assertions).  However,  this algorithm does not return
1723         captured  substrings.  A description of the two matching algorithms and         captured substrings. A description of the two matching  algorithms  and
1724         their advantages and disadvantages is given in the  pcrematching  docu-         their  advantages  and disadvantages is given in the pcrematching docu-
1725         mentation.         mentation.
1726    
1727         In  addition  to  the  main compiling and matching functions, there are         In addition to the main compiling and  matching  functions,  there  are
1728         convenience functions for extracting captured substrings from a subject         convenience functions for extracting captured substrings from a subject
1729         string that is matched by pcre_exec(). They are:         string that is matched by pcre_exec(). They are:
1730    
# Line 1738  PCRE API OVERVIEW Line 1739  PCRE API OVERVIEW
1739         pcre_free_substring() and pcre_free_substring_list() are also provided,         pcre_free_substring() and pcre_free_substring_list() are also provided,
1740         to free the memory used for extracted strings.         to free the memory used for extracted strings.
1741    
1742         The function pcre_maketables() is used to  build  a  set  of  character         The  function  pcre_maketables()  is  used  to build a set of character
1743         tables   in   the   current   locale  for  passing  to  pcre_compile(),         tables  in  the  current  locale   for   passing   to   pcre_compile(),
1744         pcre_exec(), or pcre_dfa_exec(). This is an optional facility  that  is         pcre_exec(),  or  pcre_dfa_exec(). This is an optional facility that is
1745         provided  for  specialist  use.  Most  commonly,  no special tables are         provided for specialist use.  Most  commonly,  no  special  tables  are
1746         passed, in which case internal tables that are generated when  PCRE  is         passed,  in  which case internal tables that are generated when PCRE is
1747         built are used.         built are used.
1748    
1749         The  function  pcre_fullinfo()  is used to find out information about a         The function pcre_fullinfo() is used to find out  information  about  a
1750         compiled pattern. The function pcre_version() returns a  pointer  to  a         compiled  pattern.  The  function pcre_version() returns a pointer to a
1751         string containing the version of PCRE and its date of release.         string containing the version of PCRE and its date of release.
1752    
1753         The  function  pcre_refcount()  maintains  a  reference count in a data         The function pcre_refcount() maintains a  reference  count  in  a  data
1754         block containing a compiled pattern. This is provided for  the  benefit         block  containing  a compiled pattern. This is provided for the benefit
1755         of object-oriented applications.         of object-oriented applications.
1756    
1757         The  global  variables  pcre_malloc and pcre_free initially contain the         The global variables pcre_malloc and pcre_free  initially  contain  the
1758         entry points of the standard malloc()  and  free()  functions,  respec-         entry  points  of  the  standard malloc() and free() functions, respec-
1759         tively. PCRE calls the memory management functions via these variables,         tively. PCRE calls the memory management functions via these variables,
1760         so a calling program can replace them if it  wishes  to  intercept  the         so  a  calling  program  can replace them if it wishes to intercept the
1761         calls. This should be done before calling any PCRE functions.         calls. This should be done before calling any PCRE functions.
1762    
1763         The  global  variables  pcre_stack_malloc  and pcre_stack_free are also         The global variables pcre_stack_malloc  and  pcre_stack_free  are  also
1764         indirections to memory management functions.  These  special  functions         indirections  to  memory  management functions. These special functions
1765         are  used  only  when  PCRE is compiled to use the heap for remembering         are used only when PCRE is compiled to use  the  heap  for  remembering
1766         data, instead of recursive function calls, when running the pcre_exec()         data, instead of recursive function calls, when running the pcre_exec()
1767         function.  See  the  pcrebuild  documentation  for details of how to do         function. See the pcrebuild documentation for  details  of  how  to  do
1768         this. It is a non-standard way of building PCRE, for  use  in  environ-         this.  It  is  a non-standard way of building PCRE, for use in environ-
1769         ments  that  have  limited stacks. Because of the greater use of memory         ments that have limited stacks. Because of the greater  use  of  memory
1770         management, it runs more slowly. Separate  functions  are  provided  so         management,  it  runs  more  slowly. Separate functions are provided so
1771         that  special-purpose  external  code  can  be used for this case. When         that special-purpose external code can be  used  for  this  case.  When
1772         used, these functions are always called in a  stack-like  manner  (last         used,  these  functions  are always called in a stack-like manner (last
1773         obtained,  first freed), and always for memory blocks of the same size.         obtained, first freed), and always for memory blocks of the same  size.
1774         There is a discussion about PCRE's stack usage in the  pcrestack  docu-         There  is  a discussion about PCRE's stack usage in the pcrestack docu-
1775         mentation.         mentation.
1776    
1777         The global variable pcre_callout initially contains NULL. It can be set         The global variable pcre_callout initially contains NULL. It can be set
1778         by the caller to a "callout" function, which PCRE  will  then  call  at         by  the  caller  to  a "callout" function, which PCRE will then call at
1779         specified  points during a matching operation. Details are given in the         specified points during a matching operation. Details are given in  the
1780         pcrecallout documentation.         pcrecallout documentation.
1781    
1782    
1783  NEWLINES  NEWLINES
1784    
1785         PCRE supports five different conventions for indicating line breaks  in         PCRE  supports five different conventions for indicating line breaks in
1786         strings:  a  single  CR (carriage return) character, a single LF (line-         strings: a single CR (carriage return) character, a  single  LF  (line-
1787         feed) character, the two-character sequence CRLF, any of the three pre-         feed) character, the two-character sequence CRLF, any of the three pre-
1788         ceding,  or any Unicode newline sequence. The Unicode newline sequences         ceding, or any Unicode newline sequence. The Unicode newline  sequences
1789         are the three just mentioned, plus the single characters  VT  (vertical         are  the  three just mentioned, plus the single characters VT (vertical
1790         tab, U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line         tab, U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line
1791         separator, U+2028), and PS (paragraph separator, U+2029).         separator, U+2028), and PS (paragraph separator, U+2029).
1792    
1793         Each of the first three conventions is used by at least  one  operating         Each  of  the first three conventions is used by at least one operating
1794         system  as its standard newline sequence. When PCRE is built, a default         system as its standard newline sequence. When PCRE is built, a  default
1795         can be specified.  The default default is LF, which is the  Unix  stan-         can  be  specified.  The default default is LF, which is the Unix stan-
1796         dard.  When  PCRE  is run, the default can be overridden, either when a         dard. When PCRE is run, the default can be overridden,  either  when  a
1797         pattern is compiled, or when it is matched.         pattern is compiled, or when it is matched.
1798    
1799         At compile time, the newline convention can be specified by the options         At compile time, the newline convention can be specified by the options
1800         argument  of  pcre_compile(), or it can be specified by special text at         argument of pcre_compile(), or it can be specified by special  text  at
1801         the start of the pattern itself; this overrides any other settings. See         the start of the pattern itself; this overrides any other settings. See
1802         the pcrepattern page for details of the special character sequences.         the pcrepattern page for details of the special character sequences.
1803    
1804         In the PCRE documentation the word "newline" is used to mean "the char-         In the PCRE documentation the word "newline" is used to mean "the char-
1805         acter or pair of characters that indicate a line break". The choice  of         acter  or pair of characters that indicate a line break". The choice of
1806         newline  convention  affects  the  handling of the dot, circumflex, and         newline convention affects the handling of  the  dot,  circumflex,  and
1807         dollar metacharacters, the handling of #-comments in /x mode, and, when         dollar metacharacters, the handling of #-comments in /x mode, and, when
1808         CRLF  is a recognized line ending sequence, the match position advance-         CRLF is a recognized line ending sequence, the match position  advance-
1809         ment for a non-anchored pattern. There is more detail about this in the         ment for a non-anchored pattern. There is more detail about this in the
1810         section on pcre_exec() options below.         section on pcre_exec() options below.
1811    
1812         The  choice of newline convention does not affect the interpretation of         The choice of newline convention does not affect the interpretation  of
1813         the \n or \r escape sequences, nor does  it  affect  what  \R  matches,         the  \n  or  \r  escape  sequences, nor does it affect what \R matches,
1814         which is controlled in a similar way, but by separate options.         which is controlled in a similar way, but by separate options.
1815    
1816    
1817  MULTITHREADING  MULTITHREADING
1818    
1819         The  PCRE  functions  can be used in multi-threading applications, with         The PCRE functions can be used in  multi-threading  applications,  with
1820         the  proviso  that  the  memory  management  functions  pointed  to  by         the  proviso  that  the  memory  management  functions  pointed  to  by
1821         pcre_malloc, pcre_free, pcre_stack_malloc, and pcre_stack_free, and the         pcre_malloc, pcre_free, pcre_stack_malloc, and pcre_stack_free, and the
1822         callout function pointed to by pcre_callout, are shared by all threads.         callout function pointed to by pcre_callout, are shared by all threads.
1823    
1824         The compiled form of a regular expression is not altered during  match-         The  compiled form of a regular expression is not altered during match-
1825         ing, so the same compiled pattern can safely be used by several threads         ing, so the same compiled pattern can safely be used by several threads
1826         at once.         at once.
1827    
1828         If the just-in-time optimization feature is being used, it needs  sepa-         If  the just-in-time optimization feature is being used, it needs sepa-
1829         rate  memory stack areas for each thread. See the pcrejit documentation         rate memory stack areas for each thread. See the pcrejit  documentation
1830         for more details.         for more details.
1831    
1832    
1833  SAVING PRECOMPILED PATTERNS FOR LATER USE  SAVING PRECOMPILED PATTERNS FOR LATER USE
1834    
1835         The compiled form of a regular expression can be saved and re-used at a         The compiled form of a regular expression can be saved and re-used at a
1836         later  time,  possibly by a different program, and even on a host other         later time, possibly by a different program, and even on a  host  other
1837         than the one on which  it  was  compiled.  Details  are  given  in  the         than  the  one  on  which  it  was  compiled.  Details are given in the
1838         pcreprecompile  documentation,  which  includes  a  description  of the         pcreprecompile documentation,  which  includes  a  description  of  the
1839         pcre_pattern_to_host_byte_order() function. However, compiling a  regu-         pcre_pattern_to_host_byte_order()  function. However, compiling a regu-
1840         lar  expression  with one version of PCRE for use with a different ver-         lar expression with one version of PCRE for use with a  different  ver-
1841         sion is not guaranteed to work and may cause crashes.         sion is not guaranteed to work and may cause crashes.
1842    
1843    
# Line 1844  CHECKING BUILD-TIME OPTIONS Line 1845  CHECKING BUILD-TIME OPTIONS
1845    
1846         int pcre_config(int what, void *where);         int pcre_config(int what, void *where);
1847    
1848         The function pcre_config() makes it possible for a PCRE client to  dis-         The  function pcre_config() makes it possible for a PCRE client to dis-
1849         cover which optional features have been compiled into the PCRE library.         cover which optional features have been compiled into the PCRE library.
1850         The pcrebuild documentation has more details about these optional  fea-         The  pcrebuild documentation has more details about these optional fea-
1851         tures.         tures.
1852    
1853         The  first  argument  for pcre_config() is an integer, specifying which         The first argument for pcre_config() is an  integer,  specifying  which
1854         information is required; the second argument is a pointer to a variable         information is required; the second argument is a pointer to a variable
1855         into  which  the  information  is placed. The returned value is zero on         into which the information is placed. The returned  value  is  zero  on
1856         success, or the negative error code PCRE_ERROR_BADOPTION if  the  value         success,  or  the negative error code PCRE_ERROR_BADOPTION if the value
1857         in  the  first argument is not recognized. The following information is         in the first argument is not recognized. The following  information  is
1858         available:         available:
1859    
1860           PCRE_CONFIG_UTF8           PCRE_CONFIG_UTF8
1861    
1862         The output is an integer that is set to one if UTF-8 support is  avail-         The  output is an integer that is set to one if UTF-8 support is avail-
1863         able;  otherwise it is set to zero. This value should normally be given         able; otherwise it is set to zero. This value should normally be  given
1864         to the 8-bit version of this function, pcre_config(). If it is given to         to the 8-bit version of this function, pcre_config(). If it is given to
1865         the   16-bit  or  32-bit  version  of  this  function,  the  result  is         the  16-bit  or  32-bit  version  of  this  function,  the  result   is
1866         PCRE_ERROR_BADOPTION.         PCRE_ERROR_BADOPTION.
1867    
1868           PCRE_CONFIG_UTF16           PCRE_CONFIG_UTF16
1869    
1870         The output is an integer that is set to one if UTF-16 support is avail-         The output is an integer that is set to one if UTF-16 support is avail-
1871         able;  otherwise it is set to zero. This value should normally be given         able; otherwise it is set to zero. This value should normally be  given
1872         to the 16-bit version of this function, pcre16_config(). If it is given         to the 16-bit version of this function, pcre16_config(). If it is given
1873         to  the  8-bit  or  32-bit  version  of  this  function,  the result is         to the 8-bit  or  32-bit  version  of  this  function,  the  result  is
1874         PCRE_ERROR_BADOPTION.         PCRE_ERROR_BADOPTION.
1875    
1876           PCRE_CONFIG_UTF32           PCRE_CONFIG_UTF32
1877    
1878         The output is an integer that is set to one if UTF-32 support is avail-         The output is an integer that is set to one if UTF-32 support is avail-
1879         able;  otherwise it is set to zero. This value should normally be given         able; otherwise it is set to zero. This value should normally be  given
1880         to the 32-bit version of this function, pcre32_config(). If it is given         to the 32-bit version of this function, pcre32_config(). If it is given
1881         to  the  8-bit  or  16-bit  version  of  this  function,  the result is         to the 8-bit  or  16-bit  version  of  this  function,  the  result  is
1882         PCRE_ERROR_BADOPTION.         PCRE_ERROR_BADOPTION.
1883    
1884           PCRE_CONFIG_UNICODE_PROPERTIES           PCRE_CONFIG_UNICODE_PROPERTIES
1885    
1886         The output is an integer that is set to  one  if  support  for  Unicode         The  output  is  an  integer  that is set to one if support for Unicode
1887         character properties is available; otherwise it is set to zero.         character properties is available; otherwise it is set to zero.
1888    
1889           PCRE_CONFIG_JIT           PCRE_CONFIG_JIT
# Line 1892  CHECKING BUILD-TIME OPTIONS Line 1893  CHECKING BUILD-TIME OPTIONS
1893    
1894           PCRE_CONFIG_JITTARGET           PCRE_CONFIG_JITTARGET
1895    
1896         The output is a pointer to a zero-terminated "const char *" string.  If         The  output is a pointer to a zero-terminated "const char *" string. If
1897         JIT support is available, the string contains the name of the architec-         JIT support is available, the string contains the name of the architec-
1898         ture for which the JIT compiler is configured, for example  "x86  32bit         ture  for  which the JIT compiler is configured, for example "x86 32bit
1899         (little  endian  +  unaligned)".  If  JIT support is not available, the         (little endian + unaligned)". If JIT  support  is  not  available,  the
1900         result is NULL.         result is NULL.
1901    
1902           PCRE_CONFIG_NEWLINE           PCRE_CONFIG_NEWLINE
1903    
1904         The output is an integer whose value specifies  the  default  character         The  output  is  an integer whose value specifies the default character
1905         sequence  that  is recognized as meaning "newline". The values that are         sequence that is recognized as meaning "newline". The values  that  are
1906         supported in ASCII/Unicode environments are: 10 for LF, 13 for CR, 3338         supported in ASCII/Unicode environments are: 10 for LF, 13 for CR, 3338
1907         for  CRLF,  -2 for ANYCRLF, and -1 for ANY. In EBCDIC environments, CR,         for CRLF, -2 for ANYCRLF, and -1 for ANY. In EBCDIC  environments,  CR,
1908         ANYCRLF, and ANY yield the same values. However, the value  for  LF  is         ANYCRLF,  and  ANY  yield the same values. However, the value for LF is
1909         normally  21, though some EBCDIC environments use 37. The corresponding         normally 21, though some EBCDIC environments use 37. The  corresponding
1910         values for CRLF are 3349 and 3365. The default should  normally  corre-         values  for  CRLF are 3349 and 3365. The default should normally corre-
1911         spond to the standard sequence for your operating system.         spond to the standard sequence for your operating system.
1912    
1913           PCRE_CONFIG_BSR           PCRE_CONFIG_BSR
1914    
1915         The output is an integer whose value indicates what character sequences         The output is an integer whose value indicates what character sequences
1916         the \R escape sequence matches by default. A value of 0 means  that  \R         the  \R  escape sequence matches by default. A value of 0 means that \R
1917         matches  any  Unicode  line ending sequence; a value of 1 means that \R         matches any Unicode line ending sequence; a value of 1  means  that  \R
1918         matches only CR, LF, or CRLF. The default can be overridden when a pat-         matches only CR, LF, or CRLF. The default can be overridden when a pat-
1919         tern is compiled or matched.         tern is compiled or matched.
1920    
1921           PCRE_CONFIG_LINK_SIZE           PCRE_CONFIG_LINK_SIZE
1922    
1923         The  output  is  an  integer that contains the number of bytes used for         The output is an integer that contains the number  of  bytes  used  for
1924         internal  linkage  in  compiled  regular  expressions.  For  the  8-bit         internal  linkage  in  compiled  regular  expressions.  For  the  8-bit
1925         library, the value can be 2, 3, or 4. For the 16-bit library, the value         library, the value can be 2, 3, or 4. For the 16-bit library, the value
1926         is either 2 or 4 and is  still  a  number  of  bytes.  For  the  32-bit         is  either  2  or  4  and  is  still  a number of bytes. For the 32-bit
1927         library, the value is either 2 or 4 and is still a number of bytes. The         library, the value is either 2 or 4 and is still a number of bytes. The
1928         default value of 2 is sufficient for all but the most massive patterns,         default value of 2 is sufficient for all but the most massive patterns,
1929         since  it  allows  the compiled pattern to be up to 64K in size. Larger         since it allows the compiled pattern to be up to 64K  in  size.  Larger
1930         values allow larger regular expressions to be compiled, at the  expense         values  allow larger regular expressions to be compiled, at the expense
1931         of slower matching.         of slower matching.
1932    
1933           PCRE_CONFIG_POSIX_MALLOC_THRESHOLD           PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
1934    
1935         The  output  is  an integer that contains the threshold above which the         The output is an integer that contains the threshold  above  which  the
1936         POSIX interface uses malloc() for output vectors. Further  details  are         POSIX  interface  uses malloc() for output vectors. Further details are
1937         given in the pcreposix documentation.         given in the pcreposix documentation.
1938    
1939           PCRE_CONFIG_MATCH_LIMIT           PCRE_CONFIG_MATCH_LIMIT
1940    
1941         The  output is a long integer that gives the default limit for the num-         The output is a long integer that gives the default limit for the  num-
1942         ber of internal matching function calls  in  a  pcre_exec()  execution.         ber  of  internal  matching  function calls in a pcre_exec() execution.
1943         Further details are given with pcre_exec() below.         Further details are given with pcre_exec() below.
1944    
1945           PCRE_CONFIG_MATCH_LIMIT_RECURSION           PCRE_CONFIG_MATCH_LIMIT_RECURSION
1946    
1947         The output is a long integer that gives the default limit for the depth         The output is a long integer that gives the default limit for the depth
1948         of  recursion  when  calling  the  internal  matching  function  in   a         of   recursion  when  calling  the  internal  matching  function  in  a
1949         pcre_exec()  execution.  Further  details  are  given  with pcre_exec()         pcre_exec() execution.  Further  details  are  given  with  pcre_exec()
1950         below.         below.
1951    
1952           PCRE_CONFIG_STACKRECURSE           PCRE_CONFIG_STACKRECURSE
1953    
1954         The output is an integer that is set to one if internal recursion  when         The  output is an integer that is set to one if internal recursion when
1955         running pcre_exec() is implemented by recursive function calls that use         running pcre_exec() is implemented by recursive function calls that use
1956         the stack to remember their state. This is the usual way that  PCRE  is         the  stack  to remember their state. This is the usual way that PCRE is
1957         compiled. The output is zero if PCRE was compiled to use blocks of data         compiled. The output is zero if PCRE was compiled to use blocks of data
1958         on the  heap  instead  of  recursive  function  calls.  In  this  case,         on  the  heap  instead  of  recursive  function  calls.  In  this case,
1959         pcre_stack_malloc  and  pcre_stack_free  are  called  to  manage memory         pcre_stack_malloc and  pcre_stack_free  are  called  to  manage  memory
1960         blocks on the heap, thus avoiding the use of the stack.         blocks on the heap, thus avoiding the use of the stack.
1961    
1962    
# Line 1972  COMPILING A PATTERN Line 1973  COMPILING A PATTERN
1973    
1974         Either of the functions pcre_compile() or pcre_compile2() can be called         Either of the functions pcre_compile() or pcre_compile2() can be called
1975         to compile a pattern into an internal form. The only difference between         to compile a pattern into an internal form. The only difference between
1976         the two interfaces is that pcre_compile2() has an additional  argument,         the  two interfaces is that pcre_compile2() has an additional argument,
1977         errorcodeptr,  via  which  a  numerical  error code can be returned. To         errorcodeptr, via which a numerical error  code  can  be  returned.  To
1978         avoid too much repetition, we refer just to pcre_compile()  below,  but         avoid  too  much repetition, we refer just to pcre_compile() below, but
1979         the information applies equally to pcre_compile2().         the information applies equally to pcre_compile2().
1980    
1981         The pattern is a C string terminated by a binary zero, and is passed in         The pattern is a C string terminated by a binary zero, and is passed in
1982         the pattern argument. A pointer to a single block  of  memory  that  is         the  pattern  argument.  A  pointer to a single block of memory that is
1983         obtained  via  pcre_malloc is returned. This contains the compiled code         obtained via pcre_malloc is returned. This contains the  compiled  code
1984         and related data. The pcre type is defined for the returned block; this         and related data. The pcre type is defined for the returned block; this
1985         is a typedef for a structure whose contents are not externally defined.         is a typedef for a structure whose contents are not externally defined.
1986         It is up to the caller to free the memory (via pcre_free) when it is no         It is up to the caller to free the memory (via pcre_free) when it is no
1987         longer required.         longer required.
1988    
1989         Although  the compiled code of a PCRE regex is relocatable, that is, it         Although the compiled code of a PCRE regex is relocatable, that is,  it
1990         does not depend on memory location, the complete pcre data block is not         does not depend on memory location, the complete pcre data block is not
1991         fully  relocatable, because it may contain a copy of the tableptr argu-         fully relocatable, because it may contain a copy of the tableptr  argu-
1992         ment, which is an address (see below).         ment, which is an address (see below).
1993    
1994         The options argument contains various bit settings that affect the com-         The options argument contains various bit settings that affect the com-
1995         pilation.  It  should be zero if no options are required. The available         pilation. It should be zero if no options are required.  The  available
1996         options are described below. Some of them (in  particular,  those  that         options  are  described  below. Some of them (in particular, those that
1997         are  compatible with Perl, but some others as well) can also be set and         are compatible with Perl, but some others as well) can also be set  and
1998         unset from within the pattern (see  the  detailed  description  in  the         unset  from  within  the  pattern  (see the detailed description in the
1999         pcrepattern  documentation). For those options that can be different in         pcrepattern documentation). For those options that can be different  in
2000         different parts of the pattern, the contents of  the  options  argument         different  parts  of  the pattern, the contents of the options argument
2001         specifies their settings at the start of compilation and execution. The         specifies their settings at the start of compilation and execution. The
2002         PCRE_ANCHORED, PCRE_BSR_xxx, PCRE_NEWLINE_xxx, PCRE_NO_UTF8_CHECK,  and         PCRE_ANCHORED,  PCRE_BSR_xxx, PCRE_NEWLINE_xxx, PCRE_NO_UTF8_CHECK, and
2003         PCRE_NO_START_OPTIMIZE  options  can  be set at the time of matching as         PCRE_NO_START_OPTIMIZE options can be set at the time  of  matching  as
2004         well as at compile time.         well as at compile time.
2005    
2006         If errptr is NULL, pcre_compile() returns NULL immediately.  Otherwise,         If errptr is NULL, pcre_compile() returns NULL immediately.  Otherwise,
2007         if  compilation  of  a  pattern fails, pcre_compile() returns NULL, and         if compilation of a pattern fails,  pcre_compile()  returns  NULL,  and
2008         sets the variable pointed to by errptr to point to a textual error mes-         sets the variable pointed to by errptr to point to a textual error mes-
2009         sage. This is a static string that is part of the library. You must not         sage. This is a static string that is part of the library. You must not
2010         try to free it. Normally, the offset from the start of the  pattern  to         try  to  free it. Normally, the offset from the start of the pattern to
2011         the  byte  that  was  being  processed when the error was discovered is         the byte that was being processed when  the  error  was  discovered  is
2012         placed in the variable pointed to by erroffset, which must not be  NULL         placed  in the variable pointed to by erroffset, which must not be NULL
2013         (if  it is, an immediate error is given). However, for an invalid UTF-8         (if it is, an immediate error is given). However, for an invalid  UTF-8
2014         string, the offset is that of the first byte of the failing character.         string, the offset is that of the first byte of the failing character.
2015    
2016         Some errors are not detected until the whole pattern has been  scanned;         Some  errors are not detected until the whole pattern has been scanned;
2017         in  these  cases,  the offset passed back is the length of the pattern.         in these cases, the offset passed back is the length  of  the  pattern.
2018         Note that the offset is in bytes, not characters, even in  UTF-8  mode.         Note  that  the offset is in bytes, not characters, even in UTF-8 mode.
2019         It may sometimes point into the middle of a UTF-8 character.         It may sometimes point into the middle of a UTF-8 character.
2020    
2021         If  pcre_compile2()  is  used instead of pcre_compile(), and the error-         If pcre_compile2() is used instead of pcre_compile(),  and  the  error-
2022         codeptr argument is not NULL, a non-zero error code number is  returned         codeptr  argument is not NULL, a non-zero error code number is returned
2023         via  this argument in the event of an error. This is in addition to the         via this argument in the event of an error. This is in addition to  the
2024         textual error message. Error codes and messages are listed below.         textual error message. Error codes and messages are listed below.
2025    
2026         If the final argument, tableptr, is NULL, PCRE uses a  default  set  of         If  the  final  argument, tableptr, is NULL, PCRE uses a default set of
2027         character  tables  that  are  built  when  PCRE  is compiled, using the         character tables that are  built  when  PCRE  is  compiled,  using  the
2028         default C locale. Otherwise, tableptr must be an address  that  is  the         default  C  locale.  Otherwise, tableptr must be an address that is the
2029         result  of  a  call to pcre_maketables(). This value is stored with the         result of a call to pcre_maketables(). This value is  stored  with  the
2030         compiled pattern, and used again by pcre_exec(), unless  another  table         compiled  pattern,  and used again by pcre_exec(), unless another table
2031         pointer is passed to it. For more discussion, see the section on locale         pointer is passed to it. For more discussion, see the section on locale
2032         support below.         support below.
2033    
2034         This code fragment shows a typical straightforward  call  to  pcre_com-         This  code  fragment  shows a typical straightforward call to pcre_com-
2035         pile():         pile():
2036    
2037           pcre *re;           pcre *re;
# Line 2043  COMPILING A PATTERN Line 2044  COMPILING A PATTERN
2044             &erroffset,       /* for error offset */             &erroffset,       /* for error offset */
2045             NULL);            /* use default character tables */             NULL);            /* use default character tables */
2046    
2047         The  following  names  for option bits are defined in the pcre.h header         The following names for option bits are defined in  the  pcre.h  header
2048         file:         file:
2049    
2050           PCRE_ANCHORED           PCRE_ANCHORED
2051    
2052         If this bit is set, the pattern is forced to be "anchored", that is, it         If this bit is set, the pattern is forced to be "anchored", that is, it
2053         is  constrained to match only at the first matching point in the string         is constrained to match only at the first matching point in the  string
2054         that is being searched (the "subject string"). This effect can also  be         that  is being searched (the "subject string"). This effect can also be
2055         achieved  by appropriate constructs in the pattern itself, which is the         achieved by appropriate constructs in the pattern itself, which is  the
2056         only way to do it in Perl.         only way to do it in Perl.
2057    
2058           PCRE_AUTO_CALLOUT           PCRE_AUTO_CALLOUT
2059    
2060         If this bit is set, pcre_compile() automatically inserts callout items,         If this bit is set, pcre_compile() automatically inserts callout items,
2061         all  with  number  255, before each pattern item. For discussion of the         all with number 255, before each pattern item. For  discussion  of  the
2062         callout facility, see the pcrecallout documentation.         callout facility, see the pcrecallout documentation.
2063    
2064           PCRE_BSR_ANYCRLF           PCRE_BSR_ANYCRLF
2065           PCRE_BSR_UNICODE           PCRE_BSR_UNICODE
2066    
2067         These options (which are mutually exclusive) control what the \R escape         These options (which are mutually exclusive) control what the \R escape
2068         sequence  matches.  The choice is either to match only CR, LF, or CRLF,         sequence matches. The choice is either to match only CR, LF,  or  CRLF,
2069         or to match any Unicode newline sequence. The default is specified when         or to match any Unicode newline sequence. The default is specified when
2070         PCRE is built. It can be overridden from within the pattern, or by set-         PCRE is built. It can be overridden from within the pattern, or by set-
2071         ting an option when a compiled pattern is matched.         ting an option when a compiled pattern is matched.
2072    
2073           PCRE_CASELESS           PCRE_CASELESS
2074    
2075         If this bit is set, letters in the pattern match both upper  and  lower         If  this  bit is set, letters in the pattern match both upper and lower
2076         case  letters.  It  is  equivalent  to  Perl's /i option, and it can be         case letters. It is equivalent to Perl's  /i  option,  and  it  can  be
2077         changed within a pattern by a (?i) option setting. In UTF-8 mode,  PCRE         changed  within a pattern by a (?i) option setting. In UTF-8 mode, PCRE
2078         always  understands the concept of case for characters whose values are         always understands the concept of case for characters whose values  are
2079         less than 128, so caseless matching is always possible. For  characters         less  than 128, so caseless matching is always possible. For characters
2080         with  higher  values,  the concept of case is supported if PCRE is com-         with higher values, the concept of case is supported if  PCRE  is  com-
2081         piled with Unicode property support, but not otherwise. If you want  to         piled  with Unicode property support, but not otherwise. If you want to
2082         use  caseless  matching  for  characters 128 and above, you must ensure         use caseless matching for characters 128 and  above,  you  must  ensure
2083         that PCRE is compiled with Unicode property support  as  well  as  with         that  PCRE  is  compiled  with Unicode property support as well as with
2084         UTF-8 support.         UTF-8 support.
2085    
2086           PCRE_DOLLAR_ENDONLY           PCRE_DOLLAR_ENDONLY
2087    
2088         If  this bit is set, a dollar metacharacter in the pattern matches only         If this bit is set, a dollar metacharacter in the pattern matches  only
2089         at the end of the subject string. Without this option,  a  dollar  also         at  the  end  of the subject string. Without this option, a dollar also
2090         matches  immediately before a newline at the end of the string (but not         matches immediately before a newline at the end of the string (but  not
2091         before any other newlines). The PCRE_DOLLAR_ENDONLY option  is  ignored         before  any  other newlines). The PCRE_DOLLAR_ENDONLY option is ignored
2092         if  PCRE_MULTILINE  is  set.   There is no equivalent to this option in         if PCRE_MULTILINE is set.  There is no equivalent  to  this  option  in
2093         Perl, and no way to set it within a pattern.         Perl, and no way to set it within a pattern.
2094    
2095           PCRE_DOTALL           PCRE_DOTALL
2096    
2097         If this bit is set, a dot metacharacter in the pattern matches a  char-         If  this bit is set, a dot metacharacter in the pattern matches a char-
2098         acter of any value, including one that indicates a newline. However, it         acter of any value, including one that indicates a newline. However, it
2099         only ever matches one character, even if newlines are  coded  as  CRLF.         only  ever  matches  one character, even if newlines are coded as CRLF.
2100         Without  this option, a dot does not match when the current position is         Without this option, a dot does not match when the current position  is
2101         at a newline. This option is equivalent to Perl's /s option, and it can         at a newline. This option is equivalent to Perl's /s option, and it can
2102         be  changed within a pattern by a (?s) option setting. A negative class         be changed within a pattern by a (?s) option setting. A negative  class
2103         such as [^a] always matches newline characters, independent of the set-         such as [^a] always matches newline characters, independent of the set-
2104         ting of this option.         ting of this option.
2105    
2106           PCRE_DUPNAMES           PCRE_DUPNAMES
2107    
2108         If  this  bit is set, names used to identify capturing subpatterns need         If this bit is set, names used to identify capturing  subpatterns  need
2109         not be unique. This can be helpful for certain types of pattern when it         not be unique. This can be helpful for certain types of pattern when it
2110         is  known  that  only  one instance of the named subpattern can ever be         is known that only one instance of the named  subpattern  can  ever  be
2111         matched. There are more details of named subpatterns  below;  see  also         matched.  There  are  more details of named subpatterns below; see also
2112         the pcrepattern documentation.         the pcrepattern documentation.
2113    
2114           PCRE_EXTENDED           PCRE_EXTENDED
2115    
2116         If  this  bit  is  set,  white space data characters in the pattern are         If this bit is set, white space data  characters  in  the  pattern  are
2117         totally ignored except when escaped or inside a character class.  White         totally  ignored except when escaped or inside a character class. White
2118         space does not include the VT character (code 11). In addition, charac-         space does not include the VT character (code 11). In addition, charac-
2119         ters between an unescaped # outside a character class and the next new-         ters between an unescaped # outside a character class and the next new-
2120         line,  inclusive,  are  also  ignored.  This is equivalent to Perl's /x         line, inclusive, are also ignored. This  is  equivalent  to  Perl's  /x
2121         option, and it can be changed within a pattern by a  (?x)  option  set-         option,  and  it  can be changed within a pattern by a (?x) option set-
2122         ting.         ting.
2123    
2124         Which  characters  are  interpreted  as  newlines  is controlled by the         Which characters are interpreted  as  newlines  is  controlled  by  the
2125         options passed to pcre_compile() or by a special sequence at the  start         options  passed to pcre_compile() or by a special sequence at the start
2126         of  the  pattern, as described in the section entitled "Newline conven-         of the pattern, as described in the section entitled  "Newline  conven-
2127         tions" in the pcrepattern documentation. Note that the end of this type         tions" in the pcrepattern documentation. Note that the end of this type
2128         of  comment  is  a  literal  newline  sequence  in  the pattern; escape         of comment is  a  literal  newline  sequence  in  the  pattern;  escape
2129         sequences that happen to represent a newline do not count.         sequences that happen to represent a newline do not count.
2130    
2131         This option makes it possible to include  comments  inside  complicated         This  option  makes  it possible to include comments inside complicated
2132         patterns.   Note,  however,  that this applies only to data characters.         patterns.  Note, however, that this applies only  to  data  characters.
2133         White space  characters  may  never  appear  within  special  character         White  space  characters  may  never  appear  within  special character
2134         sequences in a pattern, for example within the sequence (?( that intro-         sequences in a pattern, for example within the sequence (?( that intro-
2135         duces a conditional subpattern.         duces a conditional subpattern.
2136    
2137           PCRE_EXTRA           PCRE_EXTRA
2138    
2139         This option was invented in order to turn on  additional  functionality         This  option  was invented in order to turn on additional functionality
2140         of  PCRE  that  is  incompatible with Perl, but it is currently of very         of PCRE that is incompatible with Perl, but it  is  currently  of  very
2141         little use. When set, any backslash in a pattern that is followed by  a         little  use. When set, any backslash in a pattern that is followed by a
2142         letter  that  has  no  special  meaning causes an error, thus reserving         letter that has no special meaning  causes  an  error,  thus  reserving
2143         these combinations for future expansion. By  default,  as  in  Perl,  a         these  combinations  for  future  expansion.  By default, as in Perl, a
2144         backslash  followed by a letter with no special meaning is treated as a         backslash followed by a letter with no special meaning is treated as  a
2145         literal. (Perl can, however, be persuaded to give an error for this, by         literal. (Perl can, however, be persuaded to give an error for this, by
2146         running  it with the -w option.) There are at present no other features         running it with the -w option.) There are at present no other  features
2147         controlled by this option. It can also be set by a (?X) option  setting         controlled  by this option. It can also be set by a (?X) option setting
2148         within a pattern.         within a pattern.
2149    
2150           PCRE_FIRSTLINE           PCRE_FIRSTLINE
2151    
2152         If  this  option  is  set,  an  unanchored pattern is required to match         If this option is set, an  unanchored  pattern  is  required  to  match
2153         before or at the first  newline  in  the  subject  string,  though  the         before  or  at  the  first  newline  in  the subject string, though the
2154         matched text may continue over the newline.         matched text may continue over the newline.
2155    
2156           PCRE_JAVASCRIPT_COMPAT           PCRE_JAVASCRIPT_COMPAT
2157    
2158         If this option is set, PCRE's behaviour is changed in some ways so that         If this option is set, PCRE's behaviour is changed in some ways so that
2159         it is compatible with JavaScript rather than Perl. The changes  are  as         it  is  compatible with JavaScript rather than Perl. The changes are as
2160         follows:         follows:
2161    
2162         (1)  A  lone  closing square bracket in a pattern causes a compile-time         (1) A lone closing square bracket in a pattern  causes  a  compile-time
2163         error, because this is illegal in JavaScript (by default it is  treated         error,  because this is illegal in JavaScript (by default it is treated
2164         as a data character). Thus, the pattern AB]CD becomes illegal when this         as a data character). Thus, the pattern AB]CD becomes illegal when this
2165         option is set.         option is set.
2166    
2167         (2) At run time, a back reference to an unset subpattern group  matches         (2)  At run time, a back reference to an unset subpattern group matches
2168         an  empty  string (by default this causes the current matching alterna-         an empty string (by default this causes the current  matching  alterna-
2169         tive to fail). A pattern such as (\1)(a) succeeds when this  option  is         tive  to  fail). A pattern such as (\1)(a) succeeds when this option is
2170         set  (assuming  it can find an "a" in the subject), whereas it fails by         set (assuming it can find an "a" in the subject), whereas it  fails  by
2171         default, for Perl compatibility.         default, for Perl compatibility.
2172    
2173         (3) \U matches an upper case "U" character; by default \U causes a com-         (3) \U matches an upper case "U" character; by default \U causes a com-
2174         pile time error (Perl uses \U to upper case subsequent characters).         pile time error (Perl uses \U to upper case subsequent characters).
2175    
2176         (4) \u matches a lower case "u" character unless it is followed by four         (4) \u matches a lower case "u" character unless it is followed by four
2177         hexadecimal digits, in which case the hexadecimal  number  defines  the         hexadecimal  digits,  in  which case the hexadecimal number defines the
2178         code  point  to match. By default, \u causes a compile time error (Perl         code point to match. By default, \u causes a compile time  error  (Perl
2179         uses it to upper case the following character).         uses it to upper case the following character).
2180    
2181         (5) \x matches a lower case "x" character unless it is followed by  two         (5)  \x matches a lower case "x" character unless it is followed by two
2182         hexadecimal  digits,  in  which case the hexadecimal number defines the         hexadecimal digits, in which case the hexadecimal  number  defines  the
2183         code point to match. By default, as in Perl, a  hexadecimal  number  is         code  point  to  match. By default, as in Perl, a hexadecimal number is
2184         always expected after \x, but it may have zero, one, or two digits (so,         always expected after \x, but it may have zero, one, or two digits (so,
2185         for example, \xz matches a binary zero character followed by z).         for example, \xz matches a binary zero character followed by z).
2186    
2187           PCRE_MULTILINE           PCRE_MULTILINE
2188    
2189         By default, PCRE treats the subject string as consisting  of  a  single         By  default,  PCRE  treats the subject string as consisting of a single
2190         line  of characters (even if it actually contains newlines). The "start         line of characters (even if it actually contains newlines). The  "start
2191         of line" metacharacter (^) matches only at the  start  of  the  string,         of  line"  metacharacter  (^)  matches only at the start of the string,
2192         while  the  "end  of line" metacharacter ($) matches only at the end of         while the "end of line" metacharacter ($) matches only at  the  end  of
2193         the string, or before a terminating newline (unless PCRE_DOLLAR_ENDONLY         the string, or before a terminating newline (unless PCRE_DOLLAR_ENDONLY
2194         is set). This is the same as Perl.         is set). This is the same as Perl.
2195    
2196         When  PCRE_MULTILINE  it  is set, the "start of line" and "end of line"         When PCRE_MULTILINE it is set, the "start of line" and  "end  of  line"
2197         constructs match immediately following or immediately  before  internal         constructs  match  immediately following or immediately before internal
2198         newlines  in  the  subject string, respectively, as well as at the very         newlines in the subject string, respectively, as well as  at  the  very
2199         start and end. This is equivalent to Perl's /m option, and  it  can  be         start  and  end.  This is equivalent to Perl's /m option, and it can be
2200         changed within a pattern by a (?m) option setting. If there are no new-         changed within a pattern by a (?m) option setting. If there are no new-
2201         lines in a subject string, or no occurrences of ^ or $  in  a  pattern,         lines  in  a  subject string, or no occurrences of ^ or $ in a pattern,
2202         setting PCRE_MULTILINE has no effect.         setting PCRE_MULTILINE has no effect.
2203    
2204           PCRE_NEWLINE_CR           PCRE_NEWLINE_CR
# Line 2206  COMPILING A PATTERN Line 2207  COMPILING A PATTERN
2207           PCRE_NEWLINE_ANYCRLF           PCRE_NEWLINE_ANYCRLF
2208           PCRE_NEWLINE_ANY           PCRE_NEWLINE_ANY
2209    
2210         These  options  override the default newline definition that was chosen         These options override the default newline definition that  was  chosen
2211         when PCRE was built. Setting the first or the second specifies  that  a         when  PCRE  was built. Setting the first or the second specifies that a
2212         newline  is  indicated  by a single character (CR or LF, respectively).         newline is indicated by a single character (CR  or  LF,  respectively).
2213         Setting PCRE_NEWLINE_CRLF specifies that a newline is indicated by  the         Setting  PCRE_NEWLINE_CRLF specifies that a newline is indicated by the
2214         two-character  CRLF  sequence.  Setting  PCRE_NEWLINE_ANYCRLF specifies         two-character CRLF  sequence.  Setting  PCRE_NEWLINE_ANYCRLF  specifies
2215         that any of the three preceding sequences should be recognized. Setting         that any of the three preceding sequences should be recognized. Setting
2216         PCRE_NEWLINE_ANY  specifies that any Unicode newline sequence should be         PCRE_NEWLINE_ANY specifies that any Unicode newline sequence should  be
2217         recognized.         recognized.
2218    
2219         In an ASCII/Unicode environment, the Unicode newline sequences are  the         In  an ASCII/Unicode environment, the Unicode newline sequences are the
2220         three  just  mentioned,  plus  the  single characters VT (vertical tab,         three just mentioned, plus the  single  characters  VT  (vertical  tab,
2221         U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line sep-         U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line sep-
2222         arator,  U+2028),  and  PS (paragraph separator, U+2029). For the 8-bit         arator, U+2028), and PS (paragraph separator, U+2029).  For  the  8-bit
2223         library, the last two are recognized only in UTF-8 mode.         library, the last two are recognized only in UTF-8 mode.
2224    
2225         When PCRE is compiled to run in an EBCDIC (mainframe) environment,  the         When  PCRE is compiled to run in an EBCDIC (mainframe) environment, the
2226         code for CR is 0x0d, the same as ASCII. However, the character code for         code for CR is 0x0d, the same as ASCII. However, the character code for
2227         LF is normally 0x15, though in some EBCDIC environments 0x25  is  used.         LF  is  normally 0x15, though in some EBCDIC environments 0x25 is used.
2228         Whichever  of  these  is  not LF is made to correspond to Unicode's NEL         Whichever of these is not LF is made to  correspond  to  Unicode's  NEL
2229         character. EBCDIC codes are all less than 256. For  more  details,  see         character.  EBCDIC  codes  are all less than 256. For more details, see
2230         the pcrebuild documentation.         the pcrebuild documentation.
2231    
2232         The  newline  setting  in  the  options  word  uses three bits that are         The newline setting in the  options  word  uses  three  bits  that  are
2233         treated as a number, giving eight possibilities. Currently only six are         treated as a number, giving eight possibilities. Currently only six are
2234         used  (default  plus the five values above). This means that if you set         used (default plus the five values above). This means that if  you  set
2235         more than one newline option, the combination may or may not be  sensi-         more  than one newline option, the combination may or may not be sensi-
2236         ble. For example, PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to         ble. For example, PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to
2237         PCRE_NEWLINE_CRLF, but other combinations may yield unused numbers  and         PCRE_NEWLINE_CRLF,  but other combinations may yield unused numbers and
2238         cause an error.         cause an error.
2239    
2240         The  only  time  that a line break in a pattern is specially recognized         The only time that a line break in a pattern  is  specially  recognized
2241         when compiling is when PCRE_EXTENDED is set. CR and LF are white  space         when  compiling is when PCRE_EXTENDED is set. CR and LF are white space
2242         characters,  and so are ignored in this mode. Also, an unescaped # out-         characters, and so are ignored in this mode. Also, an unescaped #  out-
2243         side a character class indicates a comment that lasts until  after  the         side  a  character class indicates a comment that lasts until after the
2244         next  line break sequence. In other circumstances, line break sequences         next line break sequence. In other circumstances, line break  sequences
2245         in patterns are treated as literal data.         in patterns are treated as literal data.
2246    
2247         The newline option that is set at compile time becomes the default that         The newline option that is set at compile time becomes the default that
# Line 2249  COMPILING A PATTERN Line 2250  COMPILING A PATTERN
2250           PCRE_NO_AUTO_CAPTURE           PCRE_NO_AUTO_CAPTURE
2251    
2252         If this option is set, it disables the use of numbered capturing paren-         If this option is set, it disables the use of numbered capturing paren-
2253         theses in the pattern. Any opening parenthesis that is not followed  by         theses  in the pattern. Any opening parenthesis that is not followed by
2254         ?  behaves as if it were followed by ?: but named parentheses can still         ? behaves as if it were followed by ?: but named parentheses can  still
2255         be used for capturing (and they acquire  numbers  in  the  usual  way).         be  used  for  capturing  (and  they acquire numbers in the usual way).
2256         There is no equivalent of this option in Perl.         There is no equivalent of this option in Perl.
2257    
2258           NO_START_OPTIMIZE           NO_START_OPTIMIZE
2259    
2260         This  is an option that acts at matching time; that is, it is really an         This is an option that acts at matching time; that is, it is really  an
2261         option for pcre_exec() or pcre_dfa_exec(). If  it  is  set  at  compile         option  for  pcre_exec()  or  pcre_dfa_exec().  If it is set at compile
2262         time,  it is remembered with the compiled pattern and assumed at match-         time, it is remembered with the compiled pattern and assumed at  match-
2263         ing time. For details  see  the  discussion  of  PCRE_NO_START_OPTIMIZE         ing  time.  For  details  see  the discussion of PCRE_NO_START_OPTIMIZE
2264         below.         below.
2265    
2266           PCRE_UCP           PCRE_UCP
2267    
2268         This  option changes the way PCRE processes \B, \b, \D, \d, \S, \s, \W,         This option changes the way PCRE processes \B, \b, \D, \d, \S, \s,  \W,
2269         \w, and some of the POSIX character classes.  By  default,  only  ASCII         \w,  and  some  of  the POSIX character classes. By default, only ASCII
2270         characters  are  recognized, but if PCRE_UCP is set, Unicode properties         characters are recognized, but if PCRE_UCP is set,  Unicode  properties
2271         are used instead to classify characters. More details are given in  the         are  used instead to classify characters. More details are given in the
2272         section  on generic character types in the pcrepattern page. If you set         section on generic character types in the pcrepattern page. If you  set
2273         PCRE_UCP, matching one of the items it affects takes much  longer.  The         PCRE_UCP,  matching  one of the items it affects takes much longer. The
2274         option  is  available only if PCRE has been compiled with Unicode prop-         option is available only if PCRE has been compiled with  Unicode  prop-
2275         erty support.         erty support.
2276    
2277           PCRE_UNGREEDY           PCRE_UNGREEDY
2278    
2279         This option inverts the "greediness" of the quantifiers  so  that  they         This  option  inverts  the "greediness" of the quantifiers so that they
2280         are  not greedy by default, but become greedy if followed by "?". It is         are not greedy by default, but become greedy if followed by "?". It  is
2281         not compatible with Perl. It can also be set by a (?U)  option  setting         not  compatible  with Perl. It can also be set by a (?U) option setting
2282         within the pattern.         within the pattern.
2283    
2284           PCRE_UTF8           PCRE_UTF8
2285    
2286         This  option  causes PCRE to regard both the pattern and the subject as         This option causes PCRE to regard both the pattern and the  subject  as
2287         strings of UTF-8 characters instead of single-byte strings. However, it         strings of UTF-8 characters instead of single-byte strings. However, it
2288         is  available  only  when PCRE is built to include UTF support. If not,         is available only when PCRE is built to include UTF  support.  If  not,
2289         the use of this option provokes an error. Details of  how  this  option         the  use  of  this option provokes an error. Details of how this option
2290         changes the behaviour of PCRE are given in the pcreunicode page.         changes the behaviour of PCRE are given in the pcreunicode page.
2291    
2292           PCRE_NO_UTF8_CHECK           PCRE_NO_UTF8_CHECK
2293    
2294         When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is         When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is
2295         automatically checked. There is a  discussion  about  the  validity  of         automatically  checked.  There  is  a  discussion about the validity of
2296         UTF-8  strings in the pcreunicode page. If an invalid UTF-8 sequence is         UTF-8 strings in the pcreunicode page. If an invalid UTF-8 sequence  is
2297         found, pcre_compile() returns an error. If you already know  that  your         found,  pcre_compile()  returns an error. If you already know that your
2298         pattern  is valid, and you want to skip this check for performance rea-         pattern is valid, and you want to skip this check for performance  rea-
2299         sons, you can set the PCRE_NO_UTF8_CHECK option.  When it is  set,  the         sons,  you  can set the PCRE_NO_UTF8_CHECK option.  When it is set, the
2300         effect of passing an invalid UTF-8 string as a pattern is undefined. It         effect of passing an invalid UTF-8 string as a pattern is undefined. It
2301         may cause your program to crash. Note that  this  option  can  also  be         may  cause  your  program  to  crash. Note that this option can also be
2302         passed  to  pcre_exec()  and  pcre_dfa_exec(), to suppress the validity         passed to pcre_exec() and pcre_dfa_exec(),  to  suppress  the  validity
2303         checking of subject strings only. If the same string is  being  matched         checking  of  subject strings only. If the same string is being matched
2304         many  times, the option can be safely set for the second and subsequent         many times, the option can be safely set for the second and  subsequent
2305         matchings to improve performance.         matchings to improve performance.
2306    
2307    
2308  COMPILATION ERROR CODES  COMPILATION ERROR CODES
2309    
2310         The following table lists the error  codes  than  may  be  returned  by         The  following  table  lists  the  error  codes than may be returned by
2311         pcre_compile2(),  along with the error messages that may be returned by         pcre_compile2(), along with the error messages that may be returned  by
2312         both compiling functions. Note that error  messages  are  always  8-bit         both  compiling  functions.  Note  that error messages are always 8-bit
2313         ASCII  strings,  even  in 16-bit or 32-bit mode. As PCRE has developed,         ASCII strings, even in 16-bit or 32-bit mode. As  PCRE  has  developed,
2314         some error codes have fallen out of use. To avoid confusion, they  have         some  error codes have fallen out of use. To avoid confusion, they have
2315         not been re-used.         not been re-used.
2316    
2317            0  no error            0  no error
# Line 2396  COMPILATION ERROR CODES Line 2397  COMPILATION ERROR CODES
2397           76  character value in \u.... sequence is too large           76  character value in \u.... sequence is too large
2398           77  invalid UTF-32 string (specifically UTF-32)           77  invalid UTF-32 string (specifically UTF-32)
2399    
2400         The  numbers  32  and 10000 in errors 48 and 49 are defaults; different         The numbers 32 and 10000 in errors 48 and 49  are  defaults;  different
2401         values may be used if the limits were changed when PCRE was built.         values may be used if the limits were changed when PCRE was built.
2402    
2403    
# Line 2405  STUDYING A PATTERN Line 2406  STUDYING A PATTERN
2406         pcre_extra *pcre_study(const pcre *code, int options         pcre_extra *pcre_study(const pcre *code, int options
2407              const char **errptr);              const char **errptr);
2408    
2409         If a compiled pattern is going to be used several times,  it  is  worth         If  a  compiled  pattern is going to be used several times, it is worth
2410         spending more time analyzing it in order to speed up the time taken for         spending more time analyzing it in order to speed up the time taken for
2411         matching. The function pcre_study() takes a pointer to a compiled  pat-         matching.  The function pcre_study() takes a pointer to a compiled pat-
2412         tern as its first argument. If studying the pattern produces additional         tern as its first argument. If studying the pattern produces additional
2413         information that will help speed up matching,  pcre_study()  returns  a         information  that  will  help speed up matching, pcre_study() returns a
2414         pointer  to a pcre_extra block, in which the study_data field points to         pointer to a pcre_extra block, in which the study_data field points  to
2415         the results of the study.         the results of the study.
2416    
2417         The  returned  value  from  pcre_study()  can  be  passed  directly  to         The  returned  value  from  pcre_study()  can  be  passed  directly  to
2418         pcre_exec()  or  pcre_dfa_exec(). However, a pcre_extra block also con-         pcre_exec() or pcre_dfa_exec(). However, a pcre_extra block  also  con-
2419         tains other fields that can be set by the caller before  the  block  is         tains  other  fields  that can be set by the caller before the block is
2420         passed; these are described below in the section on matching a pattern.         passed; these are described below in the section on matching a pattern.
2421    
2422         If  studying  the  pattern  does  not  produce  any useful information,         If studying the  pattern  does  not  produce  any  useful  information,
2423         pcre_study() returns NULL by default.  In  that  circumstance,  if  the         pcre_study()  returns  NULL  by  default.  In that circumstance, if the
2424         calling program wants to pass any of the other fields to pcre_exec() or         calling program wants to pass any of the other fields to pcre_exec() or
2425         pcre_dfa_exec(), it must set up its own pcre_extra block.  However,  if         pcre_dfa_exec(),  it  must set up its own pcre_extra block. However, if
2426         pcre_study()  is  called  with  the  PCRE_STUDY_EXTRA_NEEDED option, it         pcre_study() is called  with  the  PCRE_STUDY_EXTRA_NEEDED  option,  it
2427         returns a pcre_extra block even if studying did not find any additional         returns a pcre_extra block even if studying did not find any additional
2428         information.  It  may still return NULL, however, if an error occurs in         information. It may still return NULL, however, if an error  occurs  in
2429         pcre_study().         pcre_study().
2430    
2431         The second argument of pcre_study() contains  option  bits.  There  are         The  second  argument  of  pcre_study() contains option bits. There are
2432         three further options in addition to PCRE_STUDY_EXTRA_NEEDED:         three further options in addition to PCRE_STUDY_EXTRA_NEEDED:
2433    
2434           PCRE_STUDY_JIT_COMPILE           PCRE_STUDY_JIT_COMPILE
2435           PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE           PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
2436           PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE           PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
2437    
2438         If  any  of  these are set, and the just-in-time compiler is available,         If any of these are set, and the just-in-time  compiler  is  available,
2439         the pattern is further compiled into machine code  that  executes  much         the  pattern  is  further compiled into machine code that executes much
2440         faster  than  the  pcre_exec()  interpretive  matching function. If the         faster than the pcre_exec()  interpretive  matching  function.  If  the
2441         just-in-time compiler is not available, these options are ignored.  All         just-in-time  compiler is not available, these options are ignored. All
2442         undefined bits in the options argument must be zero.         undefined bits in the options argument must be zero.
2443    
2444         JIT  compilation  is  a heavyweight optimization. It can take some time         JIT compilation is a heavyweight optimization. It can  take  some  time
2445         for patterns to be analyzed, and for one-off matches  and  simple  pat-         for  patterns  to  be analyzed, and for one-off matches and simple pat-
2446         terns  the benefit of faster execution might be offset by a much slower         terns the benefit of faster execution might be offset by a much  slower
2447         study time.  Not all patterns can be optimized by the JIT compiler. For         study time.  Not all patterns can be optimized by the JIT compiler. For
2448         those  that cannot be handled, matching automatically falls back to the         those that cannot be handled, matching automatically falls back to  the
2449         pcre_exec() interpreter. For more details, see the  pcrejit  documenta-         pcre_exec()  interpreter.  For more details, see the pcrejit documenta-
2450         tion.         tion.
2451    
2452         The  third argument for pcre_study() is a pointer for an error message.         The third argument for pcre_study() is a pointer for an error  message.
2453         If studying succeeds (even if no data is  returned),  the  variable  it         If  studying  succeeds  (even  if no data is returned), the variable it
2454         points  to  is  set  to NULL. Otherwise it is set to point to a textual         points to is set to NULL. Otherwise it is set to  point  to  a  textual
2455         error message. This is a static string that is part of the library. You         error message. This is a static string that is part of the library. You
2456         must  not  try  to  free it. You should test the error pointer for NULL         must not try to free it. You should test the  error  pointer  for  NULL
2457         after calling pcre_study(), to be sure that it has run successfully.         after calling pcre_study(), to be sure that it has run successfully.
2458    
2459         When you are finished with a pattern, you can free the memory used  for         When  you are finished with a pattern, you can free the memory used for
2460         the study data by calling pcre_free_study(). This function was added to         the study data by calling pcre_free_study(). This function was added to
2461         the API for release 8.20. For earlier versions,  the  memory  could  be         the  API  for  release  8.20. For earlier versions, the memory could be
2462         freed  with  pcre_free(), just like the pattern itself. This will still         freed with pcre_free(), just like the pattern itself. This  will  still
2463         work in cases where JIT optimization is not used, but it  is  advisable         work  in  cases where JIT optimization is not used, but it is advisable
2464         to change to the new function when convenient.         to change to the new function when convenient.
2465    
2466         This  is  a typical way in which pcre_study() is used (except that in a         This is a typical way in which pcre_study() is used (except that  in  a
2467         real application there should be tests for errors):         real application there should be tests for errors):
2468    
2469           int rc;           int rc;
# Line 2482  STUDYING A PATTERN Line 2483  STUDYING A PATTERN
2483         Studying a pattern does two things: first, a lower bound for the length         Studying a pattern does two things: first, a lower bound for the length
2484         of subject string that is needed to match the pattern is computed. This         of subject string that is needed to match the pattern is computed. This
2485         does not mean that there are any strings of that length that match, but         does not mean that there are any strings of that length that match, but
2486         it  does  guarantee that no shorter strings match. The value is used to         it does guarantee that no shorter strings match. The value is  used  to
2487         avoid wasting time by trying to match strings that are shorter than the         avoid wasting time by trying to match strings that are shorter than the
2488         lower  bound.  You  can find out the value in a calling program via the         lower bound. You can find out the value in a calling  program  via  the
2489         pcre_fullinfo() function.         pcre_fullinfo() function.
2490    
2491         Studying a pattern is also useful for non-anchored patterns that do not         Studying a pattern is also useful for non-anchored patterns that do not
2492         have  a  single fixed starting character. A bitmap of possible starting         have a single fixed starting character. A bitmap of  possible  starting
2493         bytes is created. This speeds up finding a position in the  subject  at         bytes  is  created. This speeds up finding a position in the subject at
2494         which to start matching. (In 16-bit mode, the bitmap is used for 16-bit         which to start matching. (In 16-bit mode, the bitmap is used for 16-bit
2495         values less than 256.  In 32-bit mode, the bitmap is  used  for  32-bit         values  less  than  256.  In 32-bit mode, the bitmap is used for 32-bit
2496         values less than 256.)         values less than 256.)
2497    
2498         These  two optimizations apply to both pcre_exec() and pcre_dfa_exec(),         These two optimizations apply to both pcre_exec() and  pcre_dfa_exec(),
2499         and the information is also used by the JIT  compiler.   The  optimiza-         and  the  information  is also used by the JIT compiler.  The optimiza-
2500         tions can be disabled by setting the PCRE_NO_START_OPTIMIZE option when         tions can be disabled by setting the PCRE_NO_START_OPTIMIZE option when
2501         calling pcre_exec() or pcre_dfa_exec(), but if this is done, JIT execu-         calling pcre_exec() or pcre_dfa_exec(), but if this is done, JIT execu-
2502         tion  is  also disabled. You might want to do this if your pattern con-         tion is also disabled. You might want to do this if your  pattern  con-
2503         tains callouts or (*MARK) and you want to make use of these  facilities         tains  callouts or (*MARK) and you want to make use of these facilities
2504         in    cases    where    matching   fails.   See   the   discussion   of         in   cases   where   matching   fails.   See    the    discussion    of
2505         PCRE_NO_START_OPTIMIZE below.         PCRE_NO_START_OPTIMIZE below.
2506    
2507    
2508  LOCALE SUPPORT  LOCALE SUPPORT
2509    
2510         PCRE handles caseless matching, and determines whether  characters  are         PCRE  handles  caseless matching, and determines whether characters are
2511         letters,  digits, or whatever, by reference to a set of tables, indexed         letters, digits, or whatever, by reference to a set of tables,  indexed
2512         by character value. When running in UTF-8 mode, this  applies  only  to         by  character  value.  When running in UTF-8 mode, this applies only to
2513         characters  with  codes  less than 128. By default, higher-valued codes         characters with codes less than 128. By  default,  higher-valued  codes
2514         never match escapes such as \w or \d, but they can be tested with \p if         never match escapes such as \w or \d, but they can be tested with \p if
2515         PCRE  is  built with Unicode character property support. Alternatively,         PCRE is built with Unicode character property  support.  Alternatively,
2516         the PCRE_UCP option can be set at compile  time;  this  causes  \w  and         the  PCRE_UCP  option  can  be  set at compile time; this causes \w and
2517         friends to use Unicode property support instead of built-in tables. The         friends to use Unicode property support instead of built-in tables. The
2518         use of locales with Unicode is discouraged. If you are handling charac-         use of locales with Unicode is discouraged. If you are handling charac-
2519         ters  with codes greater than 128, you should either use UTF-8 and Uni-         ters with codes greater than 128, you should either use UTF-8 and  Uni-
2520         code, or use locales, but not try to mix the two.         code, or use locales, but not try to mix the two.
2521    
2522         PCRE contains an internal set of tables that are used  when  the  final         PCRE  contains  an  internal set of tables that are used when the final
2523         argument  of  pcre_compile()  is  NULL.  These  are sufficient for many         argument of pcre_compile() is  NULL.  These  are  sufficient  for  many
2524         applications.  Normally, the internal tables recognize only ASCII char-         applications.  Normally, the internal tables recognize only ASCII char-
2525         acters. However, when PCRE is built, it is possible to cause the inter-         acters. However, when PCRE is built, it is possible to cause the inter-
2526         nal tables to be rebuilt in the default "C" locale of the local system,         nal tables to be rebuilt in the default "C" locale of the local system,
2527         which may cause them to be different.         which may cause them to be different.
2528    
2529         The  internal tables can always be overridden by tables supplied by the         The internal tables can always be overridden by tables supplied by  the
2530         application that calls PCRE. These may be created in a different locale         application that calls PCRE. These may be created in a different locale
2531         from  the  default.  As more and more applications change to using Uni-         from the default. As more and more applications change  to  using  Uni-
2532         code, the need for this locale support is expected to die away.         code, the need for this locale support is expected to die away.
2533    
2534         External tables are built by calling  the  pcre_maketables()  function,         External  tables  are  built by calling the pcre_maketables() function,
2535         which  has no arguments, in the relevant locale. The result can then be         which has no arguments, in the relevant locale. The result can then  be
2536         passed to pcre_compile() or pcre_exec()  as  often  as  necessary.  For         passed  to  pcre_compile()  or  pcre_exec()  as often as necessary. For
2537         example,  to  build  and use tables that are appropriate for the French         example, to build and use tables that are appropriate  for  the  French
2538         locale (where accented characters with  values  greater  than  128  are         locale  (where  accented  characters  with  values greater than 128 are
2539         treated as letters), the following code could be used:         treated as letters), the following code could be used:
2540    
2541           setlocale(LC_CTYPE, "fr_FR");           setlocale(LC_CTYPE, "fr_FR");
2542           tables = pcre_maketables();           tables = pcre_maketables();
2543           re = pcre_compile(..., tables);           re = pcre_compile(..., tables);
2544    
2545         The  locale  name "fr_FR" is used on Linux and other Unix-like systems;         The locale name "fr_FR" is used on Linux and other  Unix-like  systems;
2546         if you are using Windows, the name for the French locale is "french".         if you are using Windows, the name for the French locale is "french".
2547    
2548         When pcre_maketables() runs, the tables are built  in  memory  that  is         When  pcre_maketables()  runs,  the  tables are built in memory that is
2549         obtained  via  pcre_malloc. It is the caller's responsibility to ensure         obtained via pcre_malloc. It is the caller's responsibility  to  ensure
2550         that the memory containing the tables remains available for as long  as         that  the memory containing the tables remains available for as long as
2551         it is needed.         it is needed.
2552    
2553         The pointer that is passed to pcre_compile() is saved with the compiled         The pointer that is passed to pcre_compile() is saved with the compiled
2554         pattern, and the same tables are used via this pointer by  pcre_study()         pattern,  and the same tables are used via this pointer by pcre_study()
2555         and normally also by pcre_exec(). Thus, by default, for any single pat-         and normally also by pcre_exec(). Thus, by default, for any single pat-
2556         tern, compilation, studying and matching all happen in the same locale,         tern, compilation, studying and matching all happen in the same locale,
2557         but different patterns can be compiled in different locales.         but different patterns can be compiled in different locales.
2558    
2559         It  is  possible to pass a table pointer or NULL (indicating the use of         It is possible to pass a table pointer or NULL (indicating the  use  of
2560         the internal tables) to pcre_exec(). Although  not  intended  for  this         the  internal  tables)  to  pcre_exec(). Although not intended for this
2561         purpose,  this facility could be used to match a pattern in a different         purpose, this facility could be used to match a pattern in a  different
2562         locale from the one in which it was compiled. Passing table pointers at         locale from the one in which it was compiled. Passing table pointers at
2563         run time is discussed below in the section on matching a pattern.         run time is discussed below in the section on matching a pattern.
2564    
# Line 2567  INFORMATION ABOUT A PATTERN Line 2568  INFORMATION ABOUT A PATTERN
2568         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
2569              int what, void *where);              int what, void *where);
2570    
2571         The  pcre_fullinfo() function returns information about a compiled pat-         The pcre_fullinfo() function returns information about a compiled  pat-
2572         tern. It replaces the pcre_info() function, which was removed from  the         tern.  It replaces the pcre_info() function, which was removed from the
2573         library at version 8.30, after more than 10 years of obsolescence.         library at version 8.30, after more than 10 years of obsolescence.
2574    
2575         The  first  argument  for  pcre_fullinfo() is a pointer to the compiled         The first argument for pcre_fullinfo() is a  pointer  to  the  compiled
2576         pattern. The second argument is the result of pcre_study(), or NULL  if         pattern.  The second argument is the result of pcre_study(), or NULL if
2577         the  pattern  was not studied. The third argument specifies which piece         the pattern was not studied. The third argument specifies  which  piece
2578         of information is required, and the fourth argument is a pointer  to  a         of  information  is required, and the fourth argument is a pointer to a
2579         variable  to  receive  the  data. The yield of the function is zero for         variable to receive the data. The yield of the  function  is  zero  for
2580         success, or one of the following negative numbers:         success, or one of the following negative numbers:
2581    
2582           PCRE_ERROR_NULL           the argument code was NULL           PCRE_ERROR_NULL           the argument code was NULL
# Line 2585  INFORMATION ABOUT A PATTERN Line 2586  INFORMATION ABOUT A PATTERN
2586                                     endianness                                     endianness
2587           PCRE_ERROR_BADOPTION      the value of what was invalid           PCRE_ERROR_BADOPTION      the value of what was invalid
2588    
2589         The "magic number" is placed at the start of each compiled  pattern  as         The  "magic  number" is placed at the start of each compiled pattern as
2590         an  simple check against passing an arbitrary memory pointer. The endi-         an simple check against passing an arbitrary memory pointer. The  endi-
2591         anness error can occur if a compiled pattern is saved and reloaded on a         anness error can occur if a compiled pattern is saved and reloaded on a
2592         different  host.  Here  is a typical call of pcre_fullinfo(), to obtain         different host. Here is a typical call of  pcre_fullinfo(),  to  obtain
2593         the length of the compiled pattern:         the length of the compiled pattern:
2594    
2595           int rc;           int rc;
# Line 2599  INFORMATION ABOUT A PATTERN Line 2600  INFORMATION ABOUT A PATTERN
2600             PCRE_INFO_SIZE,   /* what is required */             PCRE_INFO_SIZE,   /* what is required */
2601             &length);         /* where to put the data */             &length);         /* where to put the data */
2602    
2603         The possible values for the third argument are defined in  pcre.h,  and         The  possible  values for the third argument are defined in pcre.h, and
2604         are as follows:         are as follows:
2605    
2606           PCRE_INFO_BACKREFMAX           PCRE_INFO_BACKREFMAX
2607    
2608         Return  the  number  of  the highest back reference in the pattern. The         Return the number of the highest back reference  in  the  pattern.  The
2609         fourth argument should point to an int variable. Zero  is  returned  if         fourth  argument  should  point to an int variable. Zero is returned if
2610         there are no back references.         there are no back references.
2611    
2612           PCRE_INFO_CAPTURECOUNT           PCRE_INFO_CAPTURECOUNT
2613    
2614         Return  the  number of capturing subpatterns in the pattern. The fourth         Return the number of capturing subpatterns in the pattern.  The  fourth
2615         argument should point to an int variable.         argument should point to an int variable.
2616    
2617           PCRE_INFO_DEFAULT_TABLES           PCRE_INFO_DEFAULT_TABLES
2618    
2619         Return a pointer to the internal default character tables within  PCRE.         Return  a pointer to the internal default character tables within PCRE.
2620         The  fourth  argument should point to an unsigned char * variable. This         The fourth argument should point to an unsigned char *  variable.  This
2621         information call is provided for internal use by the pcre_study() func-         information call is provided for internal use by the pcre_study() func-
2622         tion.  External  callers  can  cause PCRE to use its internal tables by         tion. External callers can cause PCRE to use  its  internal  tables  by
2623         passing a NULL table pointer.         passing a NULL table pointer.
2624    
2625           PCRE_INFO_FIRSTBYTE           PCRE_INFO_FIRSTBYTE
2626    
2627         Return information about the first data unit of any matched string, for         Return information about the first data unit of any matched string, for
2628         a  non-anchored  pattern.  (The name of this option refers to the 8-bit         a non-anchored pattern. (The name of this option refers  to  the  8-bit
2629         library, where data units are bytes.) The fourth argument should  point         library,  where data units are bytes.) The fourth argument should point
2630         to an int variable.         to an int variable.
2631    
2632         If  there  is  a  fixed first value, for example, the letter "c" from a         If there is a fixed first value, for example, the  letter  "c"  from  a
2633         pattern such as (cat|cow|coyote), its value is returned. In  the  8-bit         pattern  such  as (cat|cow|coyote), its value is returned. In the 8-bit
2634         library,  the  value is always less than 256. In the 16-bit library the         library, the value is always less than 256. In the 16-bit  library  the
2635         value can be up to 0xffff. In the 32-bit library the value can be up to         value can be up to 0xffff. In the 32-bit library the value can be up to
2636         0x10ffff.         0x10ffff.
2637    
2638         If there is no fixed first value, and if either         If there is no fixed first value, and if either
2639    
2640         (a)  the pattern was compiled with the PCRE_MULTILINE option, and every         (a) the pattern was compiled with the PCRE_MULTILINE option, and  every
2641         branch starts with "^", or         branch starts with "^", or
2642    
2643         (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not         (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not
2644         set (if it were set, the pattern would be anchored),         set (if it were set, the pattern would be anchored),
2645    
2646         -1  is  returned, indicating that the pattern matches only at the start         -1 is returned, indicating that the pattern matches only at  the  start
2647         of a subject string or after any newline within the  string.  Otherwise         of  a  subject string or after any newline within the string. Otherwise
2648         -2 is returned. For anchored patterns, -2 is returned.         -2 is returned. For anchored patterns, -2 is returned.
2649    
2650         Since  for  the 32-bit library using the non-UTF-32 mode, this function         Since for the 32-bit library using the non-UTF-32 mode,  this  function
2651         is unable to return the full 32-bit range of the character, this  value         is  unable to return the full 32-bit range of the character, this value
2652         is    deprecated;   instead   the   PCRE_INFO_FIRSTCHARACTERFLAGS   and         is   deprecated;   instead   the   PCRE_INFO_FIRSTCHARACTERFLAGS    and
2653         PCRE_INFO_FIRSTCHARACTER values should be used.         PCRE_INFO_FIRSTCHARACTER values should be used.
2654    
2655           PCRE_INFO_FIRSTTABLE           PCRE_INFO_FIRSTTABLE
2656    
2657         If the pattern was studied, and this resulted in the construction of  a         If  the pattern was studied, and this resulted in the construction of a
2658         256-bit  table indicating a fixed set of values for the first data unit         256-bit table indicating a fixed set of values for the first data  unit
2659         in any matching string, a pointer to the table is  returned.  Otherwise         in  any  matching string, a pointer to the table is returned. Otherwise
2660         NULL  is returned. The fourth argument should point to an unsigned char         NULL is returned. The fourth argument should point to an unsigned  char
2661         * variable.         * variable.
2662    
2663           PCRE_INFO_HASCRORLF           PCRE_INFO_HASCRORLF
2664    
2665         Return 1 if the pattern contains any explicit  matches  for  CR  or  LF         Return  1  if  the  pattern  contains any explicit matches for CR or LF
2666         characters,  otherwise  0.  The  fourth argument should point to an int         characters, otherwise 0. The fourth argument should  point  to  an  int
2667         variable. An explicit match is either a literal CR or LF character,  or         variable.  An explicit match is either a literal CR or LF character, or
2668         \r or \n.         \r or \n.
2669    
2670           PCRE_INFO_JCHANGED           PCRE_INFO_JCHANGED
2671    
2672         Return  1  if  the (?J) or (?-J) option setting is used in the pattern,         Return 1 if the (?J) or (?-J) option setting is used  in  the  pattern,
2673         otherwise 0. The fourth argument should point to an int variable.  (?J)         otherwise  0. The fourth argument should point to an int variable. (?J)
2674         and (?-J) set and unset the local PCRE_DUPNAMES option, respectively.         and (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
2675    
2676           PCRE_INFO_JIT           PCRE_INFO_JIT
2677    
2678         Return  1  if  the pattern was studied with one of the JIT options, and         Return 1 if the pattern was studied with one of the  JIT  options,  and
2679         just-in-time compiling was successful. The fourth argument should point         just-in-time compiling was successful. The fourth argument should point
2680         to  an  int variable. A return value of 0 means that JIT support is not         to an int variable. A return value of 0 means that JIT support  is  not
2681         available in this version of PCRE, or that the pattern was not  studied         available  in this version of PCRE, or that the pattern was not studied
2682         with  a JIT option, or that the JIT compiler could not handle this par-         with a JIT option, or that the JIT compiler could not handle this  par-
2683         ticular pattern. See the pcrejit documentation for details of what  can         ticular  pattern. See the pcrejit documentation for details of what can
2684         and cannot be handled.         and cannot be handled.
2685    
2686           PCRE_INFO_JITSIZE           PCRE_INFO_JITSIZE
2687    
2688         If  the  pattern was successfully studied with a JIT option, return the         If the pattern was successfully studied with a JIT option,  return  the
2689         size of the JIT compiled code, otherwise return zero. The fourth  argu-         size  of the JIT compiled code, otherwise return zero. The fourth argu-
2690         ment should point to a size_t variable.         ment should point to a size_t variable.
2691    
2692           PCRE_INFO_LASTLITERAL           PCRE_INFO_LASTLITERAL
2693    
2694         Return  the value of the rightmost literal data unit that must exist in         Return the value of the rightmost literal data unit that must exist  in
2695         any matched string, other than at its start, if such a value  has  been         any  matched  string, other than at its start, if such a value has been
2696         recorded. The fourth argument should point to an int variable. If there         recorded. The fourth argument should point to an int variable. If there
2697         is no such value, -1 is returned. For anchored patterns, a last literal         is no such value, -1 is returned. For anchored patterns, a last literal
2698         value  is recorded only if it follows something of variable length. For         value is recorded only if it follows something of variable length.  For
2699         example, for the pattern /^a\d+z\d+/ the returned value is "z", but for         example, for the pattern /^a\d+z\d+/ the returned value is "z", but for
2700         /^a\dz\d/ the returned value is -1.         /^a\dz\d/ the returned value is -1.
2701    
2702         Since  for  the 32-bit library using the non-UTF-32 mode, this function         Since for the 32-bit library using the non-UTF-32 mode,  this  function
2703         is unable to return the full 32-bit range of the character, this  value         is  unable to return the full 32-bit range of the character, this value
2704         is    deprecated;    instead    the   PCRE_INFO_REQUIREDCHARFLAGS   and         is   deprecated;   instead    the    PCRE_INFO_REQUIREDCHARFLAGS    and
2705         PCRE_INFO_REQUIREDCHAR values should be used.         PCRE_INFO_REQUIREDCHAR values should be used.
2706    
2707           PCRE_INFO_MAXLOOKBEHIND           PCRE_INFO_MAXLOOKBEHIND
2708    
2709         Return the number of characters (NB not bytes) in the  longest  lookbe-         Return  the  number of characters (NB not bytes) in the longest lookbe-
2710         hind  assertion  in the pattern. Note that the simple assertions \b and         hind assertion in the pattern. Note that the simple assertions  \b  and
2711         \B require a one-character lookbehind. This information is useful  when         \B  require a one-character lookbehind. This information is useful when
2712         doing multi-segment matching using the partial matching facilities.         doing multi-segment matching using the partial matching facilities.
2713    
2714           PCRE_INFO_MINLENGTH           PCRE_INFO_MINLENGTH
2715    
2716         If  the  pattern  was studied and a minimum length for matching subject         If the pattern was studied and a minimum length  for  matching  subject
2717         strings was computed, its value is  returned.  Otherwise  the  returned         strings  was  computed,  its  value is returned. Otherwise the returned
2718         value  is  -1. The value is a number of characters, which in UTF-8 mode         value is -1. The value is a number of characters, which in  UTF-8  mode
2719         may be different from the number of bytes. The fourth  argument  should         may  be  different from the number of bytes. The fourth argument should
2720         point  to an int variable. A non-negative value is a lower bound to the         point to an int variable. A non-negative value is a lower bound to  the
2721         length of any matching string. There may not be  any  strings  of  that         length  of  any  matching  string. There may not be any strings of that
2722         length  that  do actually match, but every string that does match is at         length that do actually match, but every string that does match  is  at
2723         least that long.         least that long.
2724    
2725           PCRE_INFO_NAMECOUNT           PCRE_INFO_NAMECOUNT
2726           PCRE_INFO_NAMEENTRYSIZE           PCRE_INFO_NAMEENTRYSIZE
2727           PCRE_INFO_NAMETABLE           PCRE_INFO_NAMETABLE
2728    
2729         PCRE supports the use of named as well as numbered capturing  parenthe-         PCRE  supports the use of named as well as numbered capturing parenthe-
2730         ses.  The names are just an additional way of identifying the parenthe-         ses. The names are just an additional way of identifying the  parenthe-
2731         ses, which still acquire numbers. Several convenience functions such as         ses, which still acquire numbers. Several convenience functions such as
2732         pcre_get_named_substring()  are  provided  for extracting captured sub-         pcre_get_named_substring() are provided for  extracting  captured  sub-
2733         strings by name. It is also possible to extract the data  directly,  by         strings  by  name. It is also possible to extract the data directly, by
2734         first  converting  the  name to a number in order to access the correct         first converting the name to a number in order to  access  the  correct
2735         pointers in the output vector (described with pcre_exec() below). To do         pointers in the output vector (described with pcre_exec() below). To do
2736         the  conversion,  you  need  to  use  the  name-to-number map, which is         the conversion, you need  to  use  the  name-to-number  map,  which  is
2737         described by these three values.         described by these three values.
2738    
2739         The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT         The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT
2740         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size
2741         of each entry; both of these  return  an  int  value.  The  entry  size         of  each  entry;  both  of  these  return  an int value. The entry size
2742         depends  on the length of the longest name. PCRE_INFO_NAMETABLE returns         depends on the length of the longest name. PCRE_INFO_NAMETABLE  returns
2743         a pointer to the first entry of the table. This is a pointer to char in         a pointer to the first entry of the table. This is a pointer to char in
2744         the 8-bit library, where the first two bytes of each entry are the num-         the 8-bit library, where the first two bytes of each entry are the num-
2745         ber of the capturing parenthesis, most significant byte first.  In  the         ber  of  the capturing parenthesis, most significant byte first. In the
2746         16-bit  library,  the pointer points to 16-bit data units, the first of         16-bit library, the pointer points to 16-bit data units, the  first  of
2747         which contains the parenthesis number.   In  the  32-bit  library,  the         which  contains  the  parenthesis  number.   In the 32-bit library, the
2748         pointer  points  to  32-bit data units, the first of which contains the         pointer points to 32-bit data units, the first of  which  contains  the
2749         parenthesis number. The rest of the entry is  the  corresponding  name,         parenthesis  number.  The  rest of the entry is the corresponding name,
2750         zero terminated.         zero terminated.
2751    
2752         The  names are in alphabetical order. Duplicate names may appear if (?|         The names are in alphabetical order. Duplicate names may appear if  (?|
2753         is used to create multiple groups with the same number, as described in         is used to create multiple groups with the same number, as described in
2754         the  section  on  duplicate subpattern numbers in the pcrepattern page.         the section on duplicate subpattern numbers in  the  pcrepattern  page.
2755         Duplicate names for subpatterns with different  numbers  are  permitted         Duplicate  names  for  subpatterns with different numbers are permitted
2756         only  if  PCRE_DUPNAMES  is  set. In all cases of duplicate names, they         only if PCRE_DUPNAMES is set. In all cases  of  duplicate  names,  they
2757         appear in the table in the order in which they were found in  the  pat-         appear  in  the table in the order in which they were found in the pat-
2758         tern.  In  the  absence  of (?| this is the order of increasing number;         tern. In the absence of (?| this is the  order  of  increasing  number;
2759         when (?| is used this is not necessarily the case because later subpat-         when (?| is used this is not necessarily the case because later subpat-
2760         terns may have lower numbers.         terns may have lower numbers.
2761    
2762         As  a  simple  example of the name/number table, consider the following         As a simple example of the name/number table,  consider  the  following
2763         pattern after compilation by the 8-bit library (assume PCRE_EXTENDED is         pattern after compilation by the 8-bit library (assume PCRE_EXTENDED is
2764         set, so white space - including newlines - is ignored):         set, so white space - including newlines - is ignored):
2765    
2766           (?<date> (?<year>(\d\d)?\d\d) -           (?<date> (?<year>(\d\d)?\d\d) -
2767           (?<month>\d\d) - (?<day>\d\d) )           (?<month>\d\d) - (?<day>\d\d) )
2768    
2769         There  are  four  named subpatterns, so the table has four entries, and         There are four named subpatterns, so the table has  four  entries,  and
2770         each entry in the table is eight bytes long. The table is  as  follows,         each  entry  in the table is eight bytes long. The table is as follows,
2771         with non-printing bytes shows in hexadecimal, and undefined bytes shown         with non-printing bytes shows in hexadecimal, and undefined bytes shown
2772         as ??:         as ??:
2773    
# Line 2775  INFORMATION ABOUT A PATTERN Line 2776  INFORMATION ABOUT A PATTERN
2776           00 04 m  o  n  t  h  00           00 04 m  o  n  t  h  00
2777           00 02 y  e  a  r  00 ??           00 02 y  e  a  r  00 ??
2778    
2779         When writing code to extract data  from  named  subpatterns  using  the         When  writing  code  to  extract  data from named subpatterns using the
2780         name-to-number  map,  remember that the length of the entries is likely         name-to-number map, remember that the length of the entries  is  likely
2781         to be different for each compiled pattern.         to be different for each compiled pattern.
2782    
2783           PCRE_INFO_OKPARTIAL           PCRE_INFO_OKPARTIAL
2784    
2785         Return 1  if  the  pattern  can  be  used  for  partial  matching  with         Return  1  if  the  pattern  can  be  used  for  partial  matching with
2786         pcre_exec(),  otherwise  0.  The fourth argument should point to an int         pcre_exec(), otherwise 0. The fourth argument should point  to  an  int
2787         variable. From  release  8.00,  this  always  returns  1,  because  the         variable.  From  release  8.00,  this  always  returns  1,  because the
2788         restrictions  that  previously  applied  to  partial matching have been         restrictions that previously applied  to  partial  matching  have  been
2789         lifted. The pcrepartial documentation gives details of  partial  match-         lifted.  The  pcrepartial documentation gives details of partial match-
2790         ing.         ing.
2791    
2792           PCRE_INFO_OPTIONS           PCRE_INFO_OPTIONS
2793    
2794         Return  a  copy of the options with which the pattern was compiled. The         Return a copy of the options with which the pattern was  compiled.  The
2795         fourth argument should point to an unsigned long  int  variable.  These         fourth  argument  should  point to an unsigned long int variable. These
2796         option bits are those specified in the call to pcre_compile(), modified         option bits are those specified in the call to pcre_compile(), modified
2797         by any top-level option settings at the start of the pattern itself. In         by any top-level option settings at the start of the pattern itself. In
2798         other  words,  they are the options that will be in force when matching         other words, they are the options that will be in force  when  matching
2799         starts. For example, if the pattern /(?im)abc(?-i)d/ is  compiled  with         starts.  For  example, if the pattern /(?im)abc(?-i)d/ is compiled with
2800         the  PCRE_EXTENDED option, the result is PCRE_CASELESS, PCRE_MULTILINE,         the PCRE_EXTENDED option, the result is PCRE_CASELESS,  PCRE_MULTILINE,
2801         and PCRE_EXTENDED.         and PCRE_EXTENDED.
2802    
2803         A pattern is automatically anchored by PCRE if  all  of  its  top-level         A  pattern  is  automatically  anchored by PCRE if all of its top-level
2804         alternatives begin with one of the following:         alternatives begin with one of the following:
2805    
2806           ^     unless PCRE_MULTILINE is set           ^     unless PCRE_MULTILINE is set
# Line 2813  INFORMATION ABOUT A PATTERN Line 2814  INFORMATION ABOUT A PATTERN
2814    
2815           PCRE_INFO_SIZE           PCRE_INFO_SIZE
2816    
2817         Return the size of the compiled pattern in bytes (for both  libraries).         Return  the size of the compiled pattern in bytes (for both libraries).
2818         The  fourth argument should point to a size_t variable. This value does         The fourth argument should point to a size_t variable. This value  does
2819         not include the  size  of  the  pcre  structure  that  is  returned  by         not  include  the  size  of  the  pcre  structure  that  is returned by
2820         pcre_compile().  The  value that is passed as the argument to pcre_mal-         pcre_compile(). The value that is passed as the argument  to  pcre_mal-
2821         loc() when pcre_compile() is getting memory in which to place the  com-         loc()  when pcre_compile() is getting memory in which to place the com-
2822         piled  data  is  the value returned by this option plus the size of the         piled data is the value returned by this option plus the  size  of  the
2823         pcre structure. Studying a compiled pattern, with or without JIT,  does         pcre  structure. Studying a compiled pattern, with or without JIT, does
2824         not alter the value returned by this option.         not alter the value returned by this option.
2825    
2826           PCRE_INFO_STUDYSIZE           PCRE_INFO_STUDYSIZE
2827    
2828         Return the size in bytes of the data block pointed to by the study_data         Return the size in bytes of the data block pointed to by the study_data
2829         field in a pcre_extra block. If pcre_extra is  NULL,  or  there  is  no         field  in  a  pcre_extra  block.  If pcre_extra is NULL, or there is no
2830         study  data,  zero  is  returned. The fourth argument should point to a         study data, zero is returned. The fourth argument  should  point  to  a
2831         size_t variable. The study_data field is set by pcre_study() to  record         size_t  variable. The study_data field is set by pcre_study() to record
2832         information  that  will  speed  up  matching  (see the section entitled         information that will speed  up  matching  (see  the  section  entitled
2833         "Studying a pattern" above). The format of the study_data block is pri-         "Studying a pattern" above). The format of the study_data block is pri-
2834         vate,  but  its length is made available via this option so that it can         vate, but its length is made available via this option so that  it  can
2835         be  saved  and  restored  (see  the  pcreprecompile  documentation  for         be  saved  and  restored  (see  the  pcreprecompile  documentation  for
2836         details).         details).
2837    
2838           PCRE_INFO_FIRSTCHARACTERFLAGS           PCRE_INFO_FIRSTCHARACTERFLAGS
2839    
2840         Return information about the first data unit of any matched string, for         Return information about the first data unit of any matched string, for
2841         a non-anchored pattern. The fourth argument  should  point  to  an  int         a  non-anchored  pattern.  The  fourth  argument should point to an int
2842         variable.         variable.
2843    
2844         If  there  is  a  fixed first value, for example, the letter "c" from a         If there is a fixed first value, for example, the  letter  "c"  from  a
2845         pattern such as (cat|cow|coyote), 1  is  returned,  and  the  character         pattern  such  as  (cat|cow|coyote),  1  is returned, and the character
2846         value can be retrieved using PCRE_INFO_FIRSTCHARACTER.         value can be retrieved using PCRE_INFO_FIRSTCHARACTER.
2847    
2848         If there is no fixed first value, and if either         If there is no fixed first value, and if either
2849    
2850         (a)  the pattern was compiled with the PCRE_MULTILINE option, and every         (a) the pattern was compiled with the PCRE_MULTILINE option, and  every
2851         branch starts with "^", or         branch starts with "^", or
2852    
2853         (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not         (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not
# Line 2858  INFORMATION ABOUT A PATTERN Line 2859  INFORMATION ABOUT A PATTERN
2859    
2860           PCRE_INFO_FIRSTCHARACTER           PCRE_INFO_FIRSTCHARACTER
2861    
2862         Return  the  fixed  first character value, if PCRE_INFO_FIRSTCHARACTER-         Return the fixed first character  value,  if  PCRE_INFO_FIRSTCHARACTER-
2863         FLAGS returned 1; otherwise returns 0. The fourth argument should point         FLAGS returned 1; otherwise returns 0. The fourth argument should point
2864         to an uint_t variable.         to an uint_t variable.
2865    
2866         In  the 8-bit library, the value is always less than 256. In the 16-bit         In the 8-bit library, the value is always less than 256. In the  16-bit
2867         library the value can be up to 0xffff. In the 32-bit library in  UTF-32         library  the value can be up to 0xffff. In the 32-bit library in UTF-32
2868         mode  the  value  can  be up to 0x10ffff, and up to 0xffffffff when not         mode the value can be up to 0x10ffff, and up  to  0xffffffff  when  not
2869         using UTF-32 mode.         using UTF-32 mode.
2870    
2871         If there is no fixed first value, and if either         If there is no fixed first value, and if either
2872    
2873         (a) the pattern was compiled with the PCRE_MULTILINE option, and  every         (a)  the pattern was compiled with the PCRE_MULTILINE option, and every
2874         branch starts with "^", or         branch starts with "^", or
2875    
2876         (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not         (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not
2877         set (if it were set, the pattern would be anchored),         set (if it were set, the pattern would be anchored),
2878    
2879         -1 is returned, indicating that the pattern matches only at  the  start         -1  is  returned, indicating that the pattern matches only at the start
2880         of  a  subject string or after any newline within the string. Otherwise         of a subject string or after any newline within the  string.  Otherwise
2881         -2 is returned. For anchored patterns, -2 is returned.         -2 is returned. For anchored patterns, -2 is returned.
2882    
2883           PCRE_INFO_REQUIREDCHARFLAGS           PCRE_INFO_REQUIREDCHARFLAGS
2884    
2885         Returns 1 if there is a rightmost literal data unit that must exist  in         Returns  1 if there is a rightmost literal data unit that must exist in
2886         any matched string, other than at its start. The fourth argument should         any matched string, other than at its start. The fourth argument should
2887         point to an int variable. If there is no such value, 0 is returned.  If         point  to an int variable. If there is no such value, 0 is returned. If
2888         returning  1,  the  character  value  itself  can  be  retrieved  using         returning  1,  the  character  value  itself  can  be  retrieved  using
2889         PCRE_INFO_REQUIREDCHAR.         PCRE_INFO_REQUIREDCHAR.
2890    
2891         For anchored patterns, a last literal value is recorded only if it fol-         For anchored patterns, a last literal value is recorded only if it fol-
2892         lows  something  of  variable  length.  For  example,  for  the pattern         lows something  of  variable  length.  For  example,  for  the  pattern
2893         /^a\d+z\d+/  the   returned   value   1   (with   "z"   returned   from         /^a\d+z\d+/   the   returned   value   1   (with   "z"   returned  from
2894         PCRE_INFO_REQUIREDCHAR), but for /^a\dz\d/ the returned value is 0.         PCRE_INFO_REQUIREDCHAR), but for /^a\dz\d/ the returned value is 0.
2895    
2896           PCRE_INFO_REQUIREDCHAR           PCRE_INFO_REQUIREDCHAR
2897    
2898         Return  the value of the rightmost literal data unit that must exist in         Return the value of the rightmost literal data unit that must exist  in
2899         any matched string, other than at its start, if such a value  has  been         any  matched  string, other than at its start, if such a value has been
2900         recorded.  The fourth argument should point to an uint32_t variable. If         recorded. The fourth argument should point to an uint32_t variable.  If
2901         there is no such value, 0 is returned.         there is no such value, 0 is returned.
2902    
2903    
# Line 2904  REFERENCE COUNTS Line 2905  REFERENCE COUNTS
2905    
2906         int pcre_refcount(pcre *code, int adjust);         int pcre_refcount(pcre *code, int adjust);
2907    
2908         The pcre_refcount() function is used to maintain a reference  count  in         The  pcre_refcount()  function is used to maintain a reference count in
2909         the data block that contains a compiled pattern. It is provided for the         the data block that contains a compiled pattern. It is provided for the
2910         benefit of applications that  operate  in  an  object-oriented  manner,         benefit  of  applications  that  operate  in an object-oriented manner,
2911         where different parts of the application may be using the same compiled         where different parts of the application may be using the same compiled
2912         pattern, but you want to free the block when they are all done.         pattern, but you want to free the block when they are all done.
2913    
2914         When a pattern is compiled, the reference count field is initialized to         When a pattern is compiled, the reference count field is initialized to
2915         zero.   It is changed only by calling this function, whose action is to         zero.  It is changed only by calling this function, whose action is  to
2916         add the adjust value (which may be positive or  negative)  to  it.  The         add  the  adjust  value  (which may be positive or negative) to it. The
2917         yield of the function is the new value. However, the value of the count         yield of the function is the new value. However, the value of the count
2918         is constrained to lie between 0 and 65535, inclusive. If the new  value         is  constrained to lie between 0 and 65535, inclusive. If the new value
2919         is outside these limits, it is forced to the appropriate limit value.         is outside these limits, it is forced to the appropriate limit value.
2920    
2921         Except  when it is zero, the reference count is not correctly preserved         Except when it is zero, the reference count is not correctly  preserved
2922         if a pattern is compiled on one host and then  transferred  to  a  host         if  a  pattern  is  compiled on one host and then transferred to a host
2923         whose byte-order is different. (This seems a highly unlikely scenario.)         whose byte-order is different. (This seems a highly unlikely scenario.)
2924    
2925    
# Line 2928  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2929  MATCHING A PATTERN: THE TRADITIONAL FUNC
2929              const char *subject, int length, int startoffset,              const char *subject, int length, int startoffset,
2930              int options, int *ovector, int ovecsize);              int options, int *ovector, int ovecsize);
2931    
2932         The  function pcre_exec() is called to match a subject string against a         The function pcre_exec() is called to match a subject string against  a
2933         compiled pattern, which is passed in the code argument. If the  pattern         compiled  pattern, which is passed in the code argument. If the pattern
2934         was  studied,  the  result  of  the study should be passed in the extra         was studied, the result of the study should  be  passed  in  the  extra
2935         argument. You can call pcre_exec() with the same code and  extra  argu-         argument.  You  can call pcre_exec() with the same code and extra argu-
2936         ments  as  many  times as you like, in order to match different subject         ments as many times as you like, in order to  match  different  subject
2937         strings with the same pattern.         strings with the same pattern.
2938    
2939         This function is the main matching facility  of  the  library,  and  it         This  function  is  the  main  matching facility of the library, and it
2940         operates  in  a  Perl-like  manner. For specialist use there is also an         operates in a Perl-like manner. For specialist use  there  is  also  an
2941         alternative matching function, which is described below in the  section         alternative  matching function, which is described below in the section
2942         about the pcre_dfa_exec() function.         about the pcre_dfa_exec() function.
2943    
2944         In  most applications, the pattern will have been compiled (and option-         In most applications, the pattern will have been compiled (and  option-
2945         ally studied) in the same process that calls pcre_exec().  However,  it         ally  studied)  in the same process that calls pcre_exec(). However, it
2946         is possible to save compiled patterns and study data, and then use them         is possible to save compiled patterns and study data, and then use them
2947         later in different processes, possibly even on different hosts.  For  a         later  in  different processes, possibly even on different hosts. For a
2948         discussion about this, see the pcreprecompile documentation.         discussion about this, see the pcreprecompile documentation.
2949    
2950         Here is an example of a simple call to pcre_exec():         Here is an example of a simple call to pcre_exec():
# Line 2962  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2963  MATCHING A PATTERN: THE TRADITIONAL FUNC
2963    
2964     Extra data for pcre_exec()     Extra data for pcre_exec()
2965    
2966         If  the  extra argument is not NULL, it must point to a pcre_extra data         If the extra argument is not NULL, it must point to a  pcre_extra  data
2967         block. The pcre_study() function returns such a block (when it  doesn't         block.  The pcre_study() function returns such a block (when it doesn't
2968         return  NULL), but you can also create one for yourself, and pass addi-         return NULL), but you can also create one for yourself, and pass  addi-
2969         tional information in it. The pcre_extra block contains  the  following         tional  information  in it. The pcre_extra block contains the following
2970         fields (not necessarily in this order):         fields (not necessarily in this order):
2971    
2972           unsigned long int flags;           unsigned long int flags;
# Line 2977  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2978  MATCHING A PATTERN: THE TRADITIONAL FUNC
2978           const unsigned char *tables;           const unsigned char *tables;
2979           unsigned char **mark;           unsigned char **mark;
2980    
2981         In  the  16-bit  version  of  this  structure,  the mark field has type         In the 16-bit version of  this  structure,  the  mark  field  has  type
2982         "PCRE_UCHAR16 **".         "PCRE_UCHAR16 **".
2983    
2984         In the 32-bit version of  this  structure,  the  mark  field  has  type         In  the  32-bit  version  of  this  structure,  the mark field has type
2985         "PCRE_UCHAR32 **".         "PCRE_UCHAR32 **".
2986    
2987         The  flags  field is used to specify which of the other fields are set.         The flags field is used to specify which of the other fields  are  set.
2988         The flag bits are:         The flag bits are:
2989    
2990           PCRE_EXTRA_CALLOUT_DATA           PCRE_EXTRA_CALLOUT_DATA
# Line 2994  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2995  MATCHING A PATTERN: THE TRADITIONAL FUNC
2995           PCRE_EXTRA_STUDY_DATA           PCRE_EXTRA_STUDY_DATA
2996           PCRE_EXTRA_TABLES           PCRE_EXTRA_TABLES
2997    
2998         Other flag bits should be set to zero. The study_data field  and  some-         Other  flag  bits should be set to zero. The study_data field and some-
2999         times  the executable_jit field are set in the pcre_extra block that is         times the executable_jit field are set in the pcre_extra block that  is
3000         returned by pcre_study(), together with the appropriate flag bits.  You         returned  by pcre_study(), together with the appropriate flag bits. You
3001         should  not set these yourself, but you may add to the block by setting         should not set these yourself, but you may add to the block by  setting
3002         other fields and their corresponding flag bits.         other fields and their corresponding flag bits.
3003    
3004         The match_limit field provides a means of preventing PCRE from using up         The match_limit field provides a means of preventing PCRE from using up
3005         a  vast amount of resources when running patterns that are not going to         a vast amount of resources when running patterns that are not going  to
3006         match, but which have a very large number  of  possibilities  in  their         match,  but  which  have  a very large number of possibilities in their
3007         search  trees. The classic example is a pattern that uses nested unlim-         search trees. The classic example is a pattern that uses nested  unlim-
3008         ited repeats.         ited repeats.
3009    
3010         Internally, pcre_exec() uses a function called match(), which it  calls         Internally,  pcre_exec() uses a function called match(), which it calls
3011         repeatedly  (sometimes  recursively).  The  limit set by match_limit is         repeatedly (sometimes recursively). The limit  set  by  match_limit  is
3012         imposed on the number of times this function is called during a  match,         imposed  on the number of times this function is called during a match,
3013         which  has  the  effect of limiting the amount of backtracking that can         which has the effect of limiting the amount of  backtracking  that  can
3014         take place. For patterns that are not anchored, the count restarts from         take place. For patterns that are not anchored, the count restarts from
3015         zero for each position in the subject string.         zero for each position in the subject string.
3016    
3017         When pcre_exec() is called with a pattern that was successfully studied         When pcre_exec() is called with a pattern that was successfully studied
3018         with a JIT option, the way that the matching is  executed  is  entirely         with  a  JIT  option, the way that the matching is executed is entirely
3019         different.  However, there is still the possibility of runaway matching         different.  However, there is still the possibility of runaway matching
3020         that goes on for a very long time, and so the match_limit value is also         that goes on for a very long time, and so the match_limit value is also
3021         used in this case (but in a different way) to limit how long the match-         used in this case (but in a different way) to limit how long the match-
3022         ing can continue.         ing can continue.
3023    
3024         The default value for the limit can be set  when  PCRE  is  built;  the         The  default  value  for  the  limit can be set when PCRE is built; the
3025         default  default  is 10 million, which handles all but the most extreme         default default is 10 million, which handles all but the  most  extreme
3026         cases. You can override the default  by  suppling  pcre_exec()  with  a         cases.  You  can  override  the  default by suppling pcre_exec() with a
3027         pcre_extra     block    in    which    match_limit    is    set,    and         pcre_extra    block    in    which    match_limit    is    set,     and
3028         PCRE_EXTRA_MATCH_LIMIT is set in the  flags  field.  If  the  limit  is         PCRE_EXTRA_MATCH_LIMIT  is  set  in  the  flags  field. If the limit is
3029         exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.         exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
3030    
3031         The  match_limit_recursion field is similar to match_limit, but instead         The match_limit_recursion field is similar to match_limit, but  instead
3032         of limiting the total number of times that match() is called, it limits         of limiting the total number of times that match() is called, it limits
3033         the  depth  of  recursion. The recursion depth is a smaller number than         the depth of recursion. The recursion depth is a  smaller  number  than
3034         the total number of calls, because not all calls to match() are  recur-         the  total number of calls, because not all calls to match() are recur-
3035         sive.  This limit is of use only if it is set smaller than match_limit.         sive.  This limit is of use only if it is set smaller than match_limit.
3036    
3037         Limiting  the  recursion  depth limits the amount of machine stack that         Limiting the recursion depth limits the amount of  machine  stack  that
3038         can be used, or, when PCRE has been compiled to use memory on the  heap         can  be used, or, when PCRE has been compiled to use memory on the heap
3039         instead  of the stack, the amount of heap memory that can be used. This         instead of the stack, the amount of heap memory that can be used.  This
3040         limit is not relevant, and is ignored, when matching is done using  JIT         limit  is not relevant, and is ignored, when matching is done using JIT
3041         compiled code.         compiled code.
3042    
3043         The  default  value  for  match_limit_recursion can be set when PCRE is         The default value for match_limit_recursion can be  set  when  PCRE  is
3044         built; the default default  is  the  same  value  as  the  default  for         built;  the  default  default  is  the  same  value  as the default for
3045         match_limit.  You can override the default by suppling pcre_exec() with         match_limit. You can override the default by suppling pcre_exec()  with
3046         a  pcre_extra  block  in  which  match_limit_recursion  is   set,   and         a   pcre_extra   block  in  which  match_limit_recursion  is  set,  and
3047         PCRE_EXTRA_MATCH_LIMIT_RECURSION  is  set  in  the  flags field. If the         PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in  the  flags  field.  If  the
3048         limit is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.         limit is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.
3049    
3050         The callout_data field is used in conjunction with the  "callout"  fea-         The  callout_data  field is used in conjunction with the "callout" fea-
3051         ture, and is described in the pcrecallout documentation.         ture, and is described in the pcrecallout documentation.
3052    
3053         The  tables  field  is  used  to  pass  a  character  tables pointer to         The tables field  is  used  to  pass  a  character  tables  pointer  to
3054         pcre_exec(); this overrides the value that is stored with the  compiled         pcre_exec();  this overrides the value that is stored with the compiled
3055         pattern.  A  non-NULL value is stored with the compiled pattern only if         pattern. A non-NULL value is stored with the compiled pattern  only  if
3056         custom tables were supplied to pcre_compile() via  its  tableptr  argu-         custom  tables  were  supplied to pcre_compile() via its tableptr argu-
3057         ment.  If NULL is passed to pcre_exec() using this mechanism, it forces         ment.  If NULL is passed to pcre_exec() using this mechanism, it forces
3058         PCRE's internal tables to be used. This facility is  helpful  when  re-         PCRE's  internal  tables  to be used. This facility is helpful when re-
3059         using  patterns  that  have been saved after compiling with an external         using patterns that have been saved after compiling  with  an  external
3060         set of tables, because the external tables  might  be  at  a  different         set  of  tables,  because  the  external tables might be at a different
3061         address  when  pcre_exec() is called. See the pcreprecompile documenta-         address when pcre_exec() is called. See the  pcreprecompile  documenta-
3062         tion for a discussion of saving compiled patterns for later use.         tion for a discussion of saving compiled patterns for later use.
3063    
3064         If PCRE_EXTRA_MARK is set in the flags field, the mark  field  must  be         If  PCRE_EXTRA_MARK  is  set in the flags field, the mark field must be
3065         set  to point to a suitable variable. If the pattern contains any back-         set to point to a suitable variable. If the pattern contains any  back-
3066         tracking control verbs such as (*MARK:NAME), and the execution ends  up         tracking  control verbs such as (*MARK:NAME), and the execution ends up
3067         with  a  name  to  pass back, a pointer to the name string (zero termi-         with a name to pass back, a pointer to the  name  string  (zero  termi-
3068         nated) is placed in the variable pointed to  by  the  mark  field.  The         nated)  is  placed  in  the  variable pointed to by the mark field. The
3069         names  are  within  the  compiled pattern; if you wish to retain such a         names are within the compiled pattern; if you wish  to  retain  such  a
3070         name you must copy it before freeing the memory of a compiled  pattern.         name  you must copy it before freeing the memory of a compiled pattern.
3071         If  there  is no name to pass back, the variable pointed to by the mark         If there is no name to pass back, the variable pointed to by  the  mark
3072         field is set to NULL. For details of the  backtracking  control  verbs,         field  is  set  to NULL. For details of the backtracking control verbs,
3073         see the section entitled "Backtracking control" in the pcrepattern doc-         see the section entitled "Backtracking control" in the pcrepattern doc-
3074         umentation.         umentation.
3075    
3076     Option bits for pcre_exec()     Option bits for pcre_exec()
3077    
3078         The unused bits of the options argument for pcre_exec() must  be  zero.         The  unused  bits of the options argument for pcre_exec() must be zero.
3079         The  only  bits  that  may  be set are PCRE_ANCHORED, PCRE_NEWLINE_xxx,         The only bits that may  be  set  are  PCRE_ANCHORED,  PCRE_NEWLINE_xxx,
3080         PCRE_NOTBOL,   PCRE_NOTEOL,    PCRE_NOTEMPTY,    PCRE_NOTEMPTY_ATSTART,         PCRE_NOTBOL,    PCRE_NOTEOL,    PCRE_NOTEMPTY,   PCRE_NOTEMPTY_ATSTART,
3081         PCRE_NO_START_OPTIMIZE,   PCRE_NO_UTF8_CHECK,   PCRE_PARTIAL_HARD,  and         PCRE_NO_START_OPTIMIZE,  PCRE_NO_UTF8_CHECK,   PCRE_PARTIAL_HARD,   and
3082         PCRE_PARTIAL_SOFT.         PCRE_PARTIAL_SOFT.
3083    
3084         If the pattern was successfully studied with one  of  the  just-in-time         If  the  pattern  was successfully studied with one of the just-in-time
3085         (JIT) compile options, the only supported options for JIT execution are         (JIT) compile options, the only supported options for JIT execution are
3086         PCRE_NO_UTF8_CHECK,    PCRE_NOTBOL,     PCRE_NOTEOL,     PCRE_NOTEMPTY,         PCRE_NO_UTF8_CHECK,     PCRE_NOTBOL,     PCRE_NOTEOL,    PCRE_NOTEMPTY,
3087         PCRE_NOTEMPTY_ATSTART,  PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT. If an         PCRE_NOTEMPTY_ATSTART, PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT. If  an
3088         unsupported option is used, JIT execution is disabled  and  the  normal         unsupported  option  is  used, JIT execution is disabled and the normal
3089         interpretive code in pcre_exec() is run.         interpretive code in pcre_exec() is run.
3090    
3091           PCRE_ANCHORED           PCRE_ANCHORED
3092    
3093         The  PCRE_ANCHORED  option  limits pcre_exec() to matching at the first         The PCRE_ANCHORED option limits pcre_exec() to matching  at  the  first
3094         matching position. If a pattern was  compiled  with  PCRE_ANCHORED,  or         matching  position.  If  a  pattern was compiled with PCRE_ANCHORED, or
3095         turned  out to be anchored by virtue of its contents, it cannot be made         turned out to be anchored by virtue of its contents, it cannot be  made
3096         unachored at matching time.         unachored at matching time.
3097    
3098           PCRE_BSR_ANYCRLF           PCRE_BSR_ANYCRLF
3099           PCRE_BSR_UNICODE           PCRE_BSR_UNICODE
3100    
3101         These options (which are mutually exclusive) control what the \R escape         These options (which are mutually exclusive) control what the \R escape
3102         sequence  matches.  The choice is either to match only CR, LF, or CRLF,         sequence matches. The choice is either to match only CR, LF,  or  CRLF,
3103         or to match any Unicode newline sequence. These  options  override  the         or  to  match  any Unicode newline sequence. These options override the
3104         choice that was made or defaulted when the pattern was compiled.         choice that was made or defaulted when the pattern was compiled.
3105    
3106           PCRE_NEWLINE_CR           PCRE_NEWLINE_CR
# Line 3108  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3109  MATCHING A PATTERN: THE TRADITIONAL FUNC
3109           PCRE_NEWLINE_ANYCRLF           PCRE_NEWLINE_ANYCRLF
3110           PCRE_NEWLINE_ANY           PCRE_NEWLINE_ANY
3111    
3112         These  options  override  the  newline  definition  that  was chosen or         These options override  the  newline  definition  that  was  chosen  or
3113         defaulted when the pattern was compiled. For details, see the  descrip-         defaulted  when the pattern was compiled. For details, see the descrip-
3114         tion  of  pcre_compile()  above.  During  matching,  the newline choice         tion of pcre_compile()  above.  During  matching,  the  newline  choice
3115         affects the behaviour of the dot, circumflex,  and  dollar  metacharac-         affects  the  behaviour  of the dot, circumflex, and dollar metacharac-
3116         ters.  It may also alter the way the match position is advanced after a         ters. It may also alter the way the match position is advanced after  a
3117         match failure for an unanchored pattern.         match failure for an unanchored pattern.
3118    
3119         When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF,  or  PCRE_NEWLINE_ANY  is         When  PCRE_NEWLINE_CRLF,  PCRE_NEWLINE_ANYCRLF,  or PCRE_NEWLINE_ANY is
3120         set,  and a match attempt for an unanchored pattern fails when the cur-         set, and a match attempt for an unanchored pattern fails when the  cur-
3121         rent position is at a  CRLF  sequence,  and  the  pattern  contains  no         rent  position  is  at  a  CRLF  sequence,  and the pattern contains no
3122         explicit  matches  for  CR  or  LF  characters,  the  match position is         explicit matches for  CR  or  LF  characters,  the  match  position  is
3123         advanced by two characters instead of one, in other words, to after the         advanced by two characters instead of one, in other words, to after the
3124         CRLF.         CRLF.
3125    
3126         The above rule is a compromise that makes the most common cases work as         The above rule is a compromise that makes the most common cases work as
3127         expected. For example, if the  pattern  is  .+A  (and  the  PCRE_DOTALL         expected.  For  example,  if  the  pattern  is .+A (and the PCRE_DOTALL
3128         option is not set), it does not match the string "\r\nA" because, after         option is not set), it does not match the string "\r\nA" because, after
3129         failing at the start, it skips both the CR and the LF before  retrying.         failing  at the start, it skips both the CR and the LF before retrying.
3130         However,  the  pattern  [\r\n]A does match that string, because it con-         However, the pattern [\r\n]A does match that string,  because  it  con-
3131         tains an explicit CR or LF reference, and so advances only by one char-         tains an explicit CR or LF reference, and so advances only by one char-
3132         acter after the first failure.         acter after the first failure.
3133    
3134         An explicit match for CR of LF is either a literal appearance of one of         An explicit match for CR of LF is either a literal appearance of one of
3135         those characters, or one of the \r or  \n  escape  sequences.  Implicit         those  characters,  or  one  of the \r or \n escape sequences. Implicit
3136         matches  such  as [^X] do not count, nor does \s (which includes CR and         matches such as [^X] do not count, nor does \s (which includes  CR  and
3137         LF in the characters that it matches).         LF in the characters that it matches).
3138    
3139         Notwithstanding the above, anomalous effects may still occur when  CRLF         Notwithstanding  the above, anomalous effects may still occur when CRLF
3140         is a valid newline sequence and explicit \r or \n escapes appear in the         is a valid newline sequence and explicit \r or \n escapes appear in the
3141         pattern.         pattern.
3142    
3143           PCRE_NOTBOL           PCRE_NOTBOL
3144    
3145         This option specifies that first character of the subject string is not         This option specifies that first character of the subject string is not
3146         the  beginning  of  a  line, so the circumflex metacharacter should not         the beginning of a line, so the  circumflex  metacharacter  should  not
3147         match before it. Setting this without PCRE_MULTILINE (at compile  time)         match  before it. Setting this without PCRE_MULTILINE (at compile time)
3148         causes  circumflex  never to match. This option affects only the behav-         causes circumflex never to match. This option affects only  the  behav-
3149         iour of the circumflex metacharacter. It does not affect \A.         iour of the circumflex metacharacter. It does not affect \A.
3150    
3151           PCRE_NOTEOL           PCRE_NOTEOL
3152    
3153         This option specifies that the end of the subject string is not the end         This option specifies that the end of the subject string is not the end
3154         of  a line, so the dollar metacharacter should not match it nor (except         of a line, so the dollar metacharacter should not match it nor  (except
3155         in multiline mode) a newline immediately before it. Setting this  with-         in  multiline mode) a newline immediately before it. Setting this with-
3156         out PCRE_MULTILINE (at compile time) causes dollar never to match. This         out PCRE_MULTILINE (at compile time) causes dollar never to match. This
3157         option affects only the behaviour of the dollar metacharacter. It  does         option  affects only the behaviour of the dollar metacharacter. It does
3158         not affect \Z or \z.         not affect \Z or \z.
3159    
3160           PCRE_NOTEMPTY           PCRE_NOTEMPTY
3161    
3162         An empty string is not considered to be a valid match if this option is         An empty string is not considered to be a valid match if this option is
3163         set. If there are alternatives in the pattern, they are tried.  If  all         set.  If  there are alternatives in the pattern, they are tried. If all
3164         the  alternatives  match  the empty string, the entire match fails. For         the alternatives match the empty string, the entire  match  fails.  For
3165         example, if the pattern         example, if the pattern
3166    
3167           a?b?           a?b?
3168    
3169         is applied to a string not beginning with "a" or  "b",  it  matches  an         is  applied  to  a  string not beginning with "a" or "b", it matches an
3170         empty  string at the start of the subject. With PCRE_NOTEMPTY set, this         empty string at the start of the subject. With PCRE_NOTEMPTY set,  this
3171         match is not valid, so PCRE searches further into the string for occur-         match is not valid, so PCRE searches further into the string for occur-
3172         rences of "a" or "b".         rences of "a" or "b".
3173    
3174           PCRE_NOTEMPTY_ATSTART           PCRE_NOTEMPTY_ATSTART
3175    
3176         This  is  like PCRE_NOTEMPTY, except that an empty string match that is         This is like PCRE_NOTEMPTY, except that an empty string match  that  is
3177         not at the start of  the  subject  is  permitted.  If  the  pattern  is         not  at  the  start  of  the  subject  is  permitted. If the pattern is
3178         anchored, such a match can occur only if the pattern contains \K.         anchored, such a match can occur only if the pattern contains \K.
3179    
3180         Perl     has    no    direct    equivalent    of    PCRE_NOTEMPTY    or         Perl    has    no    direct    equivalent    of    PCRE_NOTEMPTY     or
3181         PCRE_NOTEMPTY_ATSTART, but it does make a special  case  of  a  pattern         PCRE_NOTEMPTY_ATSTART,  but  it  does  make a special case of a pattern
3182         match  of  the empty string within its split() function, and when using         match of the empty string within its split() function, and  when  using
3183         the /g modifier. It is  possible  to  emulate  Perl's  behaviour  after         the  /g  modifier.  It  is  possible  to emulate Perl's behaviour after
3184         matching a null string by first trying the match again at the same off-         matching a null string by first trying the match again at the same off-
3185         set with PCRE_NOTEMPTY_ATSTART and  PCRE_ANCHORED,  and  then  if  that         set  with  PCRE_NOTEMPTY_ATSTART  and  PCRE_ANCHORED,  and then if that
3186         fails, by advancing the starting offset (see below) and trying an ordi-         fails, by advancing the starting offset (see below) and trying an ordi-
3187         nary match again. There is some code that demonstrates how to  do  this         nary  match  again. There is some code that demonstrates how to do this
3188         in  the  pcredemo sample program. In the most general case, you have to         in the pcredemo sample program. In the most general case, you  have  to
3189         check to see if the newline convention recognizes CRLF  as  a  newline,         check  to  see  if the newline convention recognizes CRLF as a newline,
3190         and  if so, and the current character is CR followed by LF, advance the         and if so, and the current character is CR followed by LF, advance  the
3191         starting offset by two characters instead of one.         starting offset by two characters instead of one.
3192    
3193           PCRE_NO_START_OPTIMIZE           PCRE_NO_START_OPTIMIZE
3194    
3195         There are a number of optimizations that pcre_exec() uses at the  start         There  are a number of optimizations that pcre_exec() uses at the start
3196         of  a  match,  in  order to speed up the process. For example, if it is         of a match, in order to speed up the process. For  example,  if  it  is
3197         known that an unanchored match must start with a specific character, it         known that an unanchored match must start with a specific character, it
3198         searches  the  subject  for that character, and fails immediately if it         searches the subject for that character, and fails  immediately  if  it
3199         cannot find it, without actually running the  main  matching  function.         cannot  find  it,  without actually running the main matching function.
3200         This means that a special item such as (*COMMIT) at the start of a pat-         This means that a special item such as (*COMMIT) at the start of a pat-
3201         tern is not considered until after a suitable starting  point  for  the         tern  is  not  considered until after a suitable starting point for the
3202         match  has been found. When callouts or (*MARK) items are in use, these         match has been found. When callouts or (*MARK) items are in use,  these
3203         "start-up" optimizations can cause them to be skipped if the pattern is         "start-up" optimizations can cause them to be skipped if the pattern is
3204         never  actually  used.  The start-up optimizations are in effect a pre-         never actually used. The start-up optimizations are in  effect  a  pre-
3205         scan of the subject that takes place before the pattern is run.         scan of the subject that takes place before the pattern is run.
3206    
3207         The PCRE_NO_START_OPTIMIZE option disables the start-up  optimizations,         The  PCRE_NO_START_OPTIMIZE option disables the start-up optimizations,
3208         possibly  causing  performance  to  suffer,  but ensuring that in cases         possibly causing performance to suffer,  but  ensuring  that  in  cases
3209         where the result is "no match", the callouts do occur, and  that  items         where  the  result is "no match", the callouts do occur, and that items
3210         such as (*COMMIT) and (*MARK) are considered at every possible starting         such as (*COMMIT) and (*MARK) are considered at every possible starting
3211         position in the subject string. If  PCRE_NO_START_OPTIMIZE  is  set  at         position  in  the  subject  string. If PCRE_NO_START_OPTIMIZE is set at
3212         compile  time,  it  cannot  be  unset  at  matching  time.  The  use of         compile time,  it  cannot  be  unset  at  matching  time.  The  use  of
3213         PCRE_NO_START_OPTIMIZE disables JIT execution; when it is set, matching         PCRE_NO_START_OPTIMIZE disables JIT execution; when it is set, matching
3214         is always done using interpretively.         is always done using interpretively.
3215    
3216         Setting  PCRE_NO_START_OPTIMIZE  can  change  the outcome of a matching         Setting PCRE_NO_START_OPTIMIZE can change the  outcome  of  a  matching
3217         operation.  Consider the pattern         operation.  Consider the pattern
3218    
3219           (*COMMIT)ABC           (*COMMIT)ABC
3220    
3221         When this is compiled, PCRE records the fact that a  match  must  start         When  this  is  compiled, PCRE records the fact that a match must start
3222         with  the  character  "A".  Suppose the subject string is "DEFABC". The         with the character "A". Suppose the subject  string  is  "DEFABC".  The
3223         start-up optimization scans along the subject, finds "A" and  runs  the         start-up  optimization  scans along the subject, finds "A" and runs the
3224         first  match attempt from there. The (*COMMIT) item means that the pat-         first match attempt from there. The (*COMMIT) item means that the  pat-
3225         tern must match the current starting position, which in this  case,  it         tern  must  match the current starting position, which in this case, it
3226         does.  However,  if  the  same match is run with PCRE_NO_START_OPTIMIZE         does. However, if the same match  is  run  with  PCRE_NO_START_OPTIMIZE
3227         set, the initial scan along the subject string  does  not  happen.  The         set,  the  initial  scan  along the subject string does not happen. The
3228         first  match  attempt  is  run  starting  from "D" and when this fails,         first match attempt is run starting  from  "D"  and  when  this  fails,
3229         (*COMMIT) prevents any further matches  being  tried,  so  the  overall         (*COMMIT)  prevents  any  further  matches  being tried, so the overall
3230         result  is  "no  match". If the pattern is studied, more start-up opti-         result is "no match". If the pattern is studied,  more  start-up  opti-
3231         mizations may be used. For example, a minimum length  for  the  subject         mizations  may  be  used. For example, a minimum length for the subject
3232         may be recorded. Consider the pattern         may be recorded. Consider the pattern
3233    
3234           (*MARK:A)(X|Y)           (*MARK:A)(X|Y)
3235    
3236         The  minimum  length  for  a  match is one character. If the subject is         The minimum length for a match is one  character.  If  the  subject  is
3237         "ABC", there will be attempts to  match  "ABC",  "BC",  "C",  and  then         "ABC",  there  will  be  attempts  to  match "ABC", "BC", "C", and then
3238         finally  an empty string.  If the pattern is studied, the final attempt         finally an empty string.  If the pattern is studied, the final  attempt
3239         does not take place, because PCRE knows that the subject is too  short,         does  not take place, because PCRE knows that the subject is too short,
3240         and  so  the  (*MARK) is never encountered.  In this case, studying the         and so the (*MARK) is never encountered.  In this  case,  studying  the
3241         pattern does not affect the overall match result, which  is  still  "no         pattern  does  not  affect the overall match result, which is still "no
3242         match", but it does affect the auxiliary information that is returned.         match", but it does affect the auxiliary information that is returned.
3243    
3244           PCRE_NO_UTF8_CHECK           PCRE_NO_UTF8_CHECK
3245    
3246         When PCRE_UTF8 is set at compile time, the validity of the subject as a         When PCRE_UTF8 is set at compile time, the validity of the subject as a
3247         UTF-8 string is automatically checked when pcre_exec() is  subsequently         UTF-8  string is automatically checked when pcre_exec() is subsequently
3248         called.  The entire string is checked before any other processing takes         called.  The entire string is checked before any other processing takes
3249         place. The value of startoffset is  also  checked  to  ensure  that  it         place.  The  value  of  startoffset  is  also checked to ensure that it
3250         points  to  the start of a UTF-8 character. There is a discussion about         points to the start of a UTF-8 character. There is a  discussion  about
3251         the validity of UTF-8 strings in the pcreunicode page.  If  an  invalid         the  validity  of  UTF-8 strings in the pcreunicode page. If an invalid
3252         sequence   of   bytes   is   found,   pcre_exec()   returns  the  error         sequence  of  bytes   is   found,   pcre_exec()   returns   the   error
3253         PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is a         PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is a
3254         truncated character at the end of the subject, PCRE_ERROR_SHORTUTF8. In         truncated character at the end of the subject, PCRE_ERROR_SHORTUTF8. In
3255         both cases, information about the precise nature of the error may  also         both  cases, information about the precise nature of the error may also
3256         be  returned (see the descriptions of these errors in the section enti-         be returned (see the descriptions of these errors in the section  enti-
3257         tled Error return values from pcre_exec() below).  If startoffset  con-         tled  Error return values from pcre_exec() below).  If startoffset con-
3258         tains a value that does not point to the start of a UTF-8 character (or         tains a value that does not point to the start of a UTF-8 character (or
3259         to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is returned.         to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is returned.
3260    
3261         If you already know that your subject is valid, and you  want  to  skip         If  you  already  know that your subject is valid, and you want to skip
3262         these    checks    for   performance   reasons,   you   can   set   the         these   checks   for   performance   reasons,   you   can    set    the
3263         PCRE_NO_UTF8_CHECK option when calling pcre_exec(). You might  want  to         PCRE_NO_UTF8_CHECK  option  when calling pcre_exec(). You might want to
3264         do  this  for the second and subsequent calls to pcre_exec() if you are         do this for the second and subsequent calls to pcre_exec() if  you  are
3265         making repeated calls to find all  the  matches  in  a  single  subject         making  repeated  calls  to  find  all  the matches in a single subject
3266         string.  However,  you  should  be  sure  that the value of startoffset         string. However, you should be  sure  that  the  value  of  startoffset
3267         points to the start of a character (or the end of  the  subject).  When         points  to  the  start of a character (or the end of the subject). When
3268         PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid string as a         PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid string as a
3269         subject or an invalid value of startoffset is undefined.  Your  program         subject  or  an invalid value of startoffset is undefined. Your program
3270         may crash.         may crash.
3271    
3272           PCRE_PARTIAL_HARD           PCRE_PARTIAL_HARD
3273           PCRE_PARTIAL_SOFT           PCRE_PARTIAL_SOFT
3274    
3275         These  options turn on the partial matching feature. For backwards com-         These options turn on the partial matching feature. For backwards  com-
3276         patibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A  partial         patibility,  PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial
3277         match  occurs if the end of the subject string is reached successfully,         match occurs if the end of the subject string is reached  successfully,
3278         but there are not enough subject characters to complete the  match.  If         but  there  are not enough subject characters to complete the match. If
3279         this happens when PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set,         this happens when PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set,
3280         matching continues by testing any remaining alternatives.  Only  if  no         matching  continues  by  testing any remaining alternatives. Only if no
3281         complete  match  can be found is PCRE_ERROR_PARTIAL returned instead of         complete match can be found is PCRE_ERROR_PARTIAL returned  instead  of
3282         PCRE_ERROR_NOMATCH. In other words,  PCRE_PARTIAL_SOFT  says  that  the         PCRE_ERROR_NOMATCH.  In  other  words,  PCRE_PARTIAL_SOFT says that the
3283         caller  is  prepared to handle a partial match, but only if no complete         caller is prepared to handle a partial match, but only if  no  complete
3284         match can be found.         match can be found.
3285    
3286         If PCRE_PARTIAL_HARD is set, it overrides  PCRE_PARTIAL_SOFT.  In  this         If  PCRE_PARTIAL_HARD  is  set, it overrides PCRE_PARTIAL_SOFT. In this
3287         case,  if  a  partial  match  is found, pcre_exec() immediately returns         case, if a partial match  is  found,  pcre_exec()  immediately  returns
3288         PCRE_ERROR_PARTIAL, without  considering  any  other  alternatives.  In         PCRE_ERROR_PARTIAL,  without  considering  any  other  alternatives. In
3289         other  words, when PCRE_PARTIAL_HARD is set, a partial match is consid-         other words, when PCRE_PARTIAL_HARD is set, a partial match is  consid-
3290         ered to be more important that an alternative complete match.         ered to be more important that an alternative complete match.
3291    
3292         In both cases, the portion of the string that was  inspected  when  the         In  both  cases,  the portion of the string that was inspected when the
3293         partial match was found is set as the first matching string. There is a         partial match was found is set as the first matching string. There is a
3294         more detailed discussion of partial and  multi-segment  matching,  with         more  detailed  discussion  of partial and multi-segment matching, with
3295         examples, in the pcrepartial documentation.         examples, in the pcrepartial documentation.
3296    
3297     The string to be matched by pcre_exec()     The string to be matched by pcre_exec()
3298    
3299         The  subject string is passed to pcre_exec() as a pointer in subject, a         The subject string is passed to pcre_exec() as a pointer in subject,  a
3300         length in bytes in length, and a starting byte offset  in  startoffset.         length  in  bytes in length, and a starting byte offset in startoffset.
3301         If  this  is  negative  or  greater  than  the  length  of the subject,         If this is  negative  or  greater  than  the  length  of  the  subject,
3302         pcre_exec() returns PCRE_ERROR_BADOFFSET. When the starting  offset  is         pcre_exec()  returns  PCRE_ERROR_BADOFFSET. When the starting offset is
3303         zero,  the  search  for a match starts at the beginning of the subject,         zero, the search for a match starts at the beginning  of  the  subject,
3304         and this is by far the most common case. In UTF-8 mode, the byte offset         and this is by far the most common case. In UTF-8 mode, the byte offset
3305         must  point  to  the start of a UTF-8 character (or the end of the sub-         must point to the start of a UTF-8 character (or the end  of  the  sub-
3306         ject). Unlike the pattern string, the subject may contain  binary  zero         ject).  Unlike  the pattern string, the subject may contain binary zero
3307         bytes.         bytes.
3308    
3309         A  non-zero  starting offset is useful when searching for another match         A non-zero starting offset is useful when searching for  another  match
3310         in the same subject by calling pcre_exec() again after a previous  suc-         in  the same subject by calling pcre_exec() again after a previous suc-
3311         cess.   Setting  startoffset differs from just passing over a shortened         cess.  Setting startoffset differs from just passing over  a  shortened
3312         string and setting PCRE_NOTBOL in the case of  a  pattern  that  begins         string  and  setting  PCRE_NOTBOL  in the case of a pattern that begins
3313         with any kind of lookbehind. For example, consider the pattern         with any kind of lookbehind. For example, consider the pattern
3314    
3315           \Biss\B           \Biss\B
3316    
3317         which  finds  occurrences  of "iss" in the middle of words. (\B matches         which finds occurrences of "iss" in the middle of  words.  (\B  matches
3318         only if the current position in the subject is not  a  word  boundary.)         only  if  the  current position in the subject is not a word boundary.)
3319         When  applied  to the string "Mississipi" the first call to pcre_exec()         When applied to the string "Mississipi" the first call  to  pcre_exec()
3320         finds the first occurrence. If pcre_exec() is called  again  with  just         finds  the  first  occurrence. If pcre_exec() is called again with just
3321         the  remainder  of  the  subject,  namely  "issipi", it does not match,         the remainder of the subject,  namely  "issipi",  it  does  not  match,
3322         because \B is always false at the start of the subject, which is deemed         because \B is always false at the start of the subject, which is deemed
3323         to  be  a  word  boundary. However, if pcre_exec() is passed the entire         to be a word boundary. However, if pcre_exec()  is  passed  the  entire
3324         string again, but with startoffset set to 4, it finds the second occur-         string again, but with startoffset set to 4, it finds the second occur-
3325         rence  of "iss" because it is able to look behind the starting point to         rence of "iss" because it is able to look behind the starting point  to
3326         discover that it is preceded by a letter.         discover that it is preceded by a letter.
3327    
3328         Finding all the matches in a subject is tricky  when  the  pattern  can         Finding  all  the  matches  in a subject is tricky when the pattern can
3329         match an empty string. It is possible to emulate Perl's /g behaviour by         match an empty string. It is possible to emulate Perl's /g behaviour by
3330         first  trying  the  match  again  at  the   same   offset,   with   the         first   trying   the   match   again  at  the  same  offset,  with  the
3331         PCRE_NOTEMPTY_ATSTART  and  PCRE_ANCHORED  options,  and  then  if that         PCRE_NOTEMPTY_ATSTART and  PCRE_ANCHORED  options,  and  then  if  that
3332         fails, advancing the starting  offset  and  trying  an  ordinary  match         fails,  advancing  the  starting  offset  and  trying an ordinary match
3333         again. There is some code that demonstrates how to do this in the pcre-         again. There is some code that demonstrates how to do this in the pcre-
3334         demo sample program. In the most general case, you have to check to see         demo sample program. In the most general case, you have to check to see
3335         if  the newline convention recognizes CRLF as a newline, and if so, and         if the newline convention recognizes CRLF as a newline, and if so,  and
3336         the current character is CR followed by LF, advance the starting offset         the current character is CR followed by LF, advance the starting offset
3337         by two characters instead of one.         by two characters instead of one.
3338    
3339         If  a  non-zero starting offset is passed when the pattern is anchored,         If a non-zero starting offset is passed when the pattern  is  anchored,
3340         one attempt to match at the given offset is made. This can only succeed         one attempt to match at the given offset is made. This can only succeed
3341         if  the  pattern  does  not require the match to be at the start of the         if the pattern does not require the match to be at  the  start  of  the
3342         subject.         subject.
3343    
3344     How pcre_exec() returns captured substrings     How pcre_exec() returns captured substrings
3345    
3346         In general, a pattern matches a certain portion of the subject, and  in         In  general, a pattern matches a certain portion of the subject, and in
3347         addition,  further  substrings  from  the  subject may be picked out by         addition, further substrings from the subject  may  be  picked  out  by
3348         parts of the pattern. Following the usage  in  Jeffrey  Friedl's  book,         parts  of  the  pattern.  Following the usage in Jeffrey Friedl's book,
3349         this  is  called "capturing" in what follows, and the phrase "capturing         this is called "capturing" in what follows, and the  phrase  "capturing
3350         subpattern" is used for a fragment of a pattern that picks out  a  sub-         subpattern"  is  used for a fragment of a pattern that picks out a sub-
3351         string.  PCRE  supports several other kinds of parenthesized subpattern         string. PCRE supports several other kinds of  parenthesized  subpattern
3352         that do not cause substrings to be captured.         that do not cause substrings to be captured.
3353    
3354         Captured substrings are returned to the caller via a vector of integers         Captured substrings are returned to the caller via a vector of integers
3355         whose  address is passed in ovector. The number of elements in the vec-         whose address is passed in ovector. The number of elements in the  vec-
3356         tor is passed in ovecsize, which must be a non-negative  number.  Note:         tor  is  passed in ovecsize, which must be a non-negative number. Note:
3357         this argument is NOT the size of ovector in bytes.         this argument is NOT the size of ovector in bytes.
3358    
3359         The  first  two-thirds of the vector is used to pass back captured sub-         The first two-thirds of the vector is used to pass back  captured  sub-
3360         strings, each substring using a pair of integers. The  remaining  third         strings,  each  substring using a pair of integers. The remaining third
3361         of  the  vector is used as workspace by pcre_exec() while matching cap-         of the vector is used as workspace by pcre_exec() while  matching  cap-
3362         turing subpatterns, and is not available for passing back  information.         turing  subpatterns, and is not available for passing back information.
3363         The  number passed in ovecsize should always be a multiple of three. If         The number passed in ovecsize should always be a multiple of three.  If
3364         it is not, it is rounded down.         it is not, it is rounded down.
3365    
3366         When a match is successful, information about  captured  substrings  is         When  a  match  is successful, information about captured substrings is
3367         returned  in  pairs  of integers, starting at the beginning of ovector,         returned in pairs of integers, starting at the  beginning  of  ovector,
3368         and continuing up to two-thirds of its length at the  most.  The  first         and  continuing  up  to two-thirds of its length at the most. The first
3369         element  of  each pair is set to the byte offset of the first character         element of each pair is set to the byte offset of the  first  character
3370         in a substring, and the second is set to the byte offset of  the  first         in  a  substring, and the second is set to the byte offset of the first
3371         character  after  the end of a substring. Note: these values are always         character after the end of a substring. Note: these values  are  always
3372         byte offsets, even in UTF-8 mode. They are not character counts.         byte offsets, even in UTF-8 mode. They are not character counts.
3373    
3374         The first pair of integers, ovector[0]  and  ovector[1],  identify  the         The  first  pair  of  integers, ovector[0] and ovector[1], identify the
3375         portion  of  the subject string matched by the entire pattern. The next         portion of the subject string matched by the entire pattern.  The  next
3376         pair is used for the first capturing subpattern, and so on.  The  value         pair  is  used for the first capturing subpattern, and so on. The value
3377         returned by pcre_exec() is one more than the highest numbered pair that         returned by pcre_exec() is one more than the highest numbered pair that
3378         has been set.  For example, if two substrings have been  captured,  the         has  been  set.  For example, if two substrings have been captured, the
3379         returned  value is 3. If there are no capturing subpatterns, the return         returned value is 3. If there are no capturing subpatterns, the  return
3380         value from a successful match is 1, indicating that just the first pair         value from a successful match is 1, indicating that just the first pair
3381         of offsets has been set.         of offsets has been set.
3382    
3383         If a capturing subpattern is matched repeatedly, it is the last portion         If a capturing subpattern is matched repeatedly, it is the last portion
3384         of the string that it matched that is returned.         of the string that it matched that is returned.
3385    
3386         If the vector is too small to hold all the captured substring  offsets,         If  the vector is too small to hold all the captured substring offsets,
3387         it is used as far as possible (up to two-thirds of its length), and the         it is used as far as possible (up to two-thirds of its length), and the
3388         function returns a value of zero. If neither the actual string  matched         function  returns a value of zero. If neither the actual string matched
3389         nor  any captured substrings are of interest, pcre_exec() may be called         nor any captured substrings are of interest, pcre_exec() may be  called
3390         with ovector passed as NULL and ovecsize as zero. However, if the  pat-         with  ovector passed as NULL and ovecsize as zero. However, if the pat-
3391         tern  contains  back  references  and  the ovector is not big enough to         tern contains back references and the ovector  is  not  big  enough  to
3392         remember the related substrings, PCRE has to get additional memory  for         remember  the related substrings, PCRE has to get additional memory for
3393         use  during matching. Thus it is usually advisable to supply an ovector         use during matching. Thus it is usually advisable to supply an  ovector
3394         of reasonable size.         of reasonable size.
3395    
3396         There are some cases where zero is returned  (indicating  vector  over-         There  are  some  cases where zero is returned (indicating vector over-
3397         flow)  when  in fact the vector is exactly the right size for the final         flow) when in fact the vector is exactly the right size for  the  final
3398         match. For example, consider the pattern         match. For example, consider the pattern
3399    
3400           (a)(?:(b)c|bd)           (a)(?:(b)c|bd)
3401    
3402         If a vector of 6 elements (allowing for only 1 captured  substring)  is         If  a  vector of 6 elements (allowing for only 1 captured substring) is
3403         given with subject string "abd", pcre_exec() will try to set the second         given with subject string "abd", pcre_exec() will try to set the second
3404         captured string, thereby recording a vector overflow, before failing to         captured string, thereby recording a vector overflow, before failing to
3405         match  "c"  and  backing  up  to  try  the second alternative. The zero         match "c" and backing up  to  try  the  second  alternative.  The  zero
3406         return, however, does correctly indicate that  the  maximum  number  of         return,  however,  does  correctly  indicate that the maximum number of
3407         slots (namely 2) have been filled. In similar cases where there is tem-         slots (namely 2) have been filled. In similar cases where there is tem-
3408         porary overflow, but the final number of used slots  is  actually  less         porary  overflow,  but  the final number of used slots is actually less
3409         than the maximum, a non-zero value is returned.         than the maximum, a non-zero value is returned.
3410    
3411         The pcre_fullinfo() function can be used to find out how many capturing         The pcre_fullinfo() function can be used to find out how many capturing
3412         subpatterns there are in a compiled  pattern.  The  smallest  size  for         subpatterns  there  are  in  a  compiled pattern. The smallest size for
3413         ovector  that  will allow for n captured substrings, in addition to the         ovector that will allow for n captured substrings, in addition  to  the
3414         offsets of the substring matched by the whole pattern, is (n+1)*3.         offsets of the substring matched by the whole pattern, is (n+1)*3.
3415    
3416         It is possible for capturing subpattern number n+1 to match  some  part         It  is  possible for capturing subpattern number n+1 to match some part
3417         of the subject when subpattern n has not been used at all. For example,         of the subject when subpattern n has not been used at all. For example,
3418         if the string "abc" is matched  against  the  pattern  (a|(z))(bc)  the         if  the  string  "abc"  is  matched against the pattern (a|(z))(bc) the
3419         return from the function is 4, and subpatterns 1 and 3 are matched, but         return from the function is 4, and subpatterns 1 and 3 are matched, but
3420         2 is not. When this happens, both values in  the  offset  pairs  corre-         2  is  not.  When  this happens, both values in the offset pairs corre-
3421         sponding to unused subpatterns are set to -1.         sponding to unused subpatterns are set to -1.
3422    
3423         Offset  values  that correspond to unused subpatterns at the end of the         Offset values that correspond to unused subpatterns at the end  of  the
3424         expression are also set to -1. For example,  if  the  string  "abc"  is         expression  are  also  set  to  -1. For example, if the string "abc" is
3425         matched  against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not         matched against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are  not
3426         matched. The return from the function is 2, because  the  highest  used         matched.  The  return  from the function is 2, because the highest used
3427         capturing  subpattern  number  is 1, and the offsets for for the second         capturing subpattern number is 1, and the offsets for  for  the  second
3428         and third capturing subpatterns (assuming the vector is  large  enough,         and  third  capturing subpatterns (assuming the vector is large enough,
3429         of course) are set to -1.         of course) are set to -1.
3430    
3431         Note:  Elements  in  the first two-thirds of ovector that do not corre-         Note: Elements in the first two-thirds of ovector that  do  not  corre-
3432         spond to capturing parentheses in the pattern are never  changed.  That         spond  to  capturing parentheses in the pattern are never changed. That
3433         is,  if  a pattern contains n capturing parentheses, no more than ovec-         is, if a pattern contains n capturing parentheses, no more  than  ovec-
3434         tor[0] to ovector[2n+1] are set by pcre_exec(). The other elements  (in         tor[0]  to ovector[2n+1] are set by pcre_exec(). The other elements (in
3435         the first two-thirds) retain whatever values they previously had.         the first two-thirds) retain whatever values they previously had.
3436    
3437         Some  convenience  functions  are  provided for extracting the captured         Some convenience functions are provided  for  extracting  the  captured
3438         substrings as separate strings. These are described below.         substrings as separate strings. These are described below.
3439    
3440     Error return values from pcre_exec()     Error return values from pcre_exec()
3441    
3442         If pcre_exec() fails, it returns a negative number. The  following  are         If  pcre_exec()  fails, it returns a negative number. The following are
3443         defined in the header file:         defined in the header file:
3444    
3445           PCRE_ERROR_NOMATCH        (-1)           PCRE_ERROR_NOMATCH        (-1)
# Line 3447  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3448  MATCHING A PATTERN: THE TRADITIONAL FUNC
3448    
3449           PCRE_ERROR_NULL           (-2)           PCRE_ERROR_NULL           (-2)
3450    
3451         Either  code  or  subject  was  passed as NULL, or ovector was NULL and         Either code or subject was passed as NULL,  or  ovector  was  NULL  and
3452         ovecsize was not zero.         ovecsize was not zero.
3453    
3454           PCRE_ERROR_BADOPTION      (-3)           PCRE_ERROR_BADOPTION      (-3)
# Line 3456  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3457  MATCHING A PATTERN: THE TRADITIONAL FUNC
3457    
3458           PCRE_ERROR_BADMAGIC       (-4)           PCRE_ERROR_BADMAGIC       (-4)
3459    
3460         PCRE stores a 4-byte "magic number" at the start of the compiled  code,         PCRE  stores a 4-byte "magic number" at the start of the compiled code,
3461         to catch the case when it is passed a junk pointer and to detect when a         to catch the case when it is passed a junk pointer and to detect when a
3462         pattern that was compiled in an environment of one endianness is run in         pattern that was compiled in an environment of one endianness is run in
3463         an  environment  with the other endianness. This is the error that PCRE         an environment with the other endianness. This is the error  that  PCRE
3464         gives when the magic number is not present.         gives when the magic number is not present.
3465    
3466           PCRE_ERROR_UNKNOWN_OPCODE (-5)           PCRE_ERROR_UNKNOWN_OPCODE (-5)
3467    
3468         While running the pattern match, an unknown item was encountered in the         While running the pattern match, an unknown item was encountered in the
3469         compiled  pattern.  This  error  could be caused by a bug in PCRE or by         compiled pattern. This error could be caused by a bug  in  PCRE  or  by
3470         overwriting of the compiled pattern.         overwriting of the compiled pattern.
3471    
3472           PCRE_ERROR_NOMEMORY       (-6)           PCRE_ERROR_NOMEMORY       (-6)
3473    
3474         If a pattern contains back references, but the ovector that  is  passed         If  a  pattern contains back references, but the ovector that is passed
3475         to pcre_exec() is not big enough to remember the referenced substrings,         to pcre_exec() is not big enough to remember the referenced substrings,
3476         PCRE gets a block of memory at the start of matching to  use  for  this         PCRE  gets  a  block of memory at the start of matching to use for this
3477         purpose.  If the call via pcre_malloc() fails, this error is given. The         purpose. If the call via pcre_malloc() fails, this error is given.  The
3478         memory is automatically freed at the end of matching.         memory is automatically freed at the end of matching.
3479    
3480         This error is also given if pcre_stack_malloc() fails  in  pcre_exec().         This  error  is also given if pcre_stack_malloc() fails in pcre_exec().
3481         This  can happen only when PCRE has been compiled with --disable-stack-         This can happen only when PCRE has been compiled with  --disable-stack-
3482         for-recursion.         for-recursion.
3483    
3484           PCRE_ERROR_NOSUBSTRING    (-7)           PCRE_ERROR_NOSUBSTRING    (-7)
3485    
3486         This error is used by the pcre_copy_substring(),  pcre_get_substring(),         This  error is used by the pcre_copy_substring(), pcre_get_substring(),
3487         and  pcre_get_substring_list()  functions  (see  below).  It  is  never         and  pcre_get_substring_list()  functions  (see  below).  It  is  never
3488         returned by pcre_exec().         returned by pcre_exec().
3489    
3490           PCRE_ERROR_MATCHLIMIT     (-8)           PCRE_ERROR_MATCHLIMIT     (-8)
3491    
3492         The backtracking limit, as specified by  the  match_limit  field  in  a         The  backtracking  limit,  as  specified  by the match_limit field in a
3493         pcre_extra  structure  (or  defaulted) was reached. See the description         pcre_extra structure (or defaulted) was reached.  See  the  description
3494         above.         above.
3495    
3496           PCRE_ERROR_CALLOUT        (-9)           PCRE_ERROR_CALLOUT        (-9)
3497    
3498         This error is never generated by pcre_exec() itself. It is provided for         This error is never generated by pcre_exec() itself. It is provided for
3499         use  by  callout functions that want to yield a distinctive error code.         use by callout functions that want to yield a distinctive  error  code.
3500         See the pcrecallout documentation for details.         See the pcrecallout documentation for details.
3501    
3502           PCRE_ERROR_BADUTF8        (-10)           PCRE_ERROR_BADUTF8        (-10)
3503    
3504         A string that contains an invalid UTF-8 byte sequence was passed  as  a         A  string  that contains an invalid UTF-8 byte sequence was passed as a
3505         subject,  and the PCRE_NO_UTF8_CHECK option was not set. If the size of         subject, and the PCRE_NO_UTF8_CHECK option was not set. If the size  of
3506         the output vector (ovecsize) is at least 2,  the  byte  offset  to  the         the  output  vector  (ovecsize)  is  at least 2, the byte offset to the
3507         start  of  the  the invalid UTF-8 character is placed in the first ele-         start of the the invalid UTF-8 character is placed in  the  first  ele-
3508         ment, and a reason code is placed in the  second  element.  The  reason         ment,  and  a  reason  code is placed in the second element. The reason
3509         codes are listed in the following section.  For backward compatibility,         codes are listed in the following section.  For backward compatibility,
3510         if PCRE_PARTIAL_HARD is set and the problem is a truncated UTF-8  char-         if  PCRE_PARTIAL_HARD is set and the problem is a truncated UTF-8 char-
3511         acter   at   the   end   of   the   subject  (reason  codes  1  to  5),         acter  at  the  end  of  the   subject   (reason   codes   1   to   5),
3512         PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8.         PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8.
3513    
3514           PCRE_ERROR_BADUTF8_OFFSET (-11)           PCRE_ERROR_BADUTF8_OFFSET (-11)
3515    
3516         The UTF-8 byte sequence that was passed as a subject  was  checked  and         The  UTF-8  byte  sequence that was passed as a subject was checked and
3517         found  to be valid (the PCRE_NO_UTF8_CHECK option was not set), but the         found to be valid (the PCRE_NO_UTF8_CHECK option was not set), but  the
3518         value of startoffset did not point to the beginning of a UTF-8  charac-         value  of startoffset did not point to the beginning of a UTF-8 charac-
3519         ter or the end of the subject.         ter or the end of the subject.
3520    
3521           PCRE_ERROR_PARTIAL        (-12)           PCRE_ERROR_PARTIAL        (-12)
3522    
3523         The  subject  string did not match, but it did match partially. See the         The subject string did not match, but it did match partially.  See  the
3524         pcrepartial documentation for details of partial matching.         pcrepartial documentation for details of partial matching.
3525    
3526           PCRE_ERROR_BADPARTIAL     (-13)           PCRE_ERROR_BADPARTIAL     (-13)
3527    
3528         This code is no longer in  use.  It  was  formerly  returned  when  the         This  code  is  no  longer  in  use.  It was formerly returned when the
3529         PCRE_PARTIAL  option  was used with a compiled pattern containing items         PCRE_PARTIAL option was used with a compiled pattern  containing  items
3530         that were  not  supported  for  partial  matching.  From  release  8.00         that  were  not  supported  for  partial  matching.  From  release 8.00
3531         onwards, there are no restrictions on partial matching.         onwards, there are no restrictions on partial matching.
3532    
3533           PCRE_ERROR_INTERNAL       (-14)           PCRE_ERROR_INTERNAL       (-14)
3534    
3535         An  unexpected  internal error has occurred. This error could be caused         An unexpected internal error has occurred. This error could  be  caused
3536         by a bug in PCRE or by overwriting of the compiled pattern.         by a bug in PCRE or by overwriting of the compiled pattern.
3537    
3538           PCRE_ERROR_BADCOUNT       (-15)           PCRE_ERROR_BADCOUNT       (-15)
# Line 3541  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3542  MATCHING A PATTERN: THE TRADITIONAL FUNC
3542           PCRE_ERROR_RECURSIONLIMIT (-21)           PCRE_ERROR_RECURSIONLIMIT (-21)
3543    
3544         The internal recursion limit, as specified by the match_limit_recursion         The internal recursion limit, as specified by the match_limit_recursion
3545         field  in  a  pcre_extra  structure (or defaulted) was reached. See the         field in a pcre_extra structure (or defaulted)  was  reached.  See  the
3546         description above.         description above.
3547    
3548           PCRE_ERROR_BADNEWLINE     (-23)           PCRE_ERROR_BADNEWLINE     (-23)
# Line 3555  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3556  MATCHING A PATTERN: THE TRADITIONAL FUNC
3556    
3557           PCRE_ERROR_SHORTUTF8      (-25)           PCRE_ERROR_SHORTUTF8      (-25)
3558    
3559         This  error  is returned instead of PCRE_ERROR_BADUTF8 when the subject         This error is returned instead of PCRE_ERROR_BADUTF8 when  the  subject
3560         string ends with a truncated UTF-8 character and the  PCRE_PARTIAL_HARD         string  ends with a truncated UTF-8 character and the PCRE_PARTIAL_HARD
3561         option  is  set.   Information  about  the  failure  is returned as for         option is set.  Information  about  the  failure  is  returned  as  for
3562         PCRE_ERROR_BADUTF8. It is in fact sufficient to detect this  case,  but         PCRE_ERROR_BADUTF8.  It  is in fact sufficient to detect this case, but
3563         this  special error code for PCRE_PARTIAL_HARD precedes the implementa-         this special error code for PCRE_PARTIAL_HARD precedes the  implementa-
3564         tion of returned information; it is retained for backwards  compatibil-         tion  of returned information; it is retained for backwards compatibil-
3565         ity.         ity.
3566    
3567           PCRE_ERROR_RECURSELOOP    (-26)           PCRE_ERROR_RECURSELOOP    (-26)
3568    
3569         This error is returned when pcre_exec() detects a recursion loop within         This error is returned when pcre_exec() detects a recursion loop within
3570         the pattern. Specifically, it means that either the whole pattern or  a         the  pattern. Specifically, it means that either the whole pattern or a
3571         subpattern  has been called recursively for the second time at the same         subpattern has been called recursively for the second time at the  same
3572         position in the subject string. Some simple patterns that might do this         position in the subject string. Some simple patterns that might do this
3573         are  detected  and faulted at compile time, but more complicated cases,         are detected and faulted at compile time, but more  complicated  cases,
3574         in particular mutual recursions between two different subpatterns, can-         in particular mutual recursions between two different subpatterns, can-
3575         not be detected until run time.         not be detected until run time.
3576    
3577           PCRE_ERROR_JIT_STACKLIMIT (-27)           PCRE_ERROR_JIT_STACKLIMIT (-27)
3578    
3579         This  error  is  returned  when a pattern that was successfully studied         This error is returned when a pattern  that  was  successfully  studied
3580         using a JIT compile option is being matched, but the  memory  available         using  a  JIT compile option is being matched, but the memory available
3581         for  the  just-in-time  processing  stack  is not large enough. See the         for the just-in-time processing stack is  not  large  enough.  See  the
3582         pcrejit documentation for more details.         pcrejit documentation for more details.
3583    
3584           PCRE_ERROR_BADMODE        (-28)           PCRE_ERROR_BADMODE        (-28)
# Line 3587  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 3588  MATCHING A PATTERN: THE TRADITIONAL FUNC
3588    
3589           PCRE_ERROR_BADENDIANNESS  (-29)           PCRE_ERROR_BADENDIANNESS  (-29)
3590    
3591         This  error  is  given  if  a  pattern  that  was compiled and saved is         This error is given if  a  pattern  that  was  compiled  and  saved  is
3592         reloaded on a host with  different  endianness.  The  utility  function         reloaded  on  a  host  with  different endianness. The utility function
3593         pcre_pattern_to_host_byte_order() can be used to convert such a pattern         pcre_pattern_to_host_byte_order() can be used to convert such a pattern
3594         so that it runs on the new host.         so that it runs on the new host.
3595    
3596           PCRE_ERROR_JIT_BADOPTION           PCRE_ERROR_JIT_BADOPTION
3597    
3598         This error is returned when a pattern  that  was  successfully  studied         This  error  is  returned  when a pattern that was successfully studied
3599         using  a  JIT  compile  option  is being matched, but the matching mode         using a JIT compile option is being  matched,  but  the  matching  mode
3600         (partial or complete match) does not correspond to any JIT  compilation         (partial  or complete match) does not correspond to any JIT compilation
3601         mode.  When  the JIT fast path function is used, this error may be also         mode. When the JIT fast path function is used, this error may  be  also
3602         given for invalid options.  See  the  pcrejit  documentation  for  more         given  for  invalid  options.  See  the  pcrejit documentation for more
3603         details.         details.
3604    
3605           PCRE_ERROR_BADLENGTH      (-32)           PCRE_ERROR_BADLENGTH      (-32)
3606    
3607         This  error is given if pcre_exec() is called with a negative value for         This error is given if pcre_exec() is called with a negative value  for
3608         the length argument.         the length argument.
3609    
3610         Error numbers -16 to -20, -22, and 30 are not used by pcre_exec().         Error numbers -16 to -20, -22, and 30 are not used by pcre_exec().
3611    
3612     Reason codes for invalid UTF-8 strings     Reason codes for invalid UTF-8 strings
3613    
3614         This section applies only  to  the  8-bit  library.  The  corresponding         This  section  applies  only  to  the  8-bit library. The corresponding
3615         information  for  the  16-bit  library is given in the pcre16 page. The         information for the 16-bit and 32-bit libraries is given in the  pcre16
3616         corresponding information for the 32-bit library is given in the pcre32         and pcre32 pages.
        page.  
3617    
3618         When pcre_exec() returns either PCRE_ERROR_BADUTF8 or PCRE_ERROR_SHORT-         When pcre_exec() returns either PCRE_ERROR_BADUTF8 or PCRE_ERROR_SHORT-
3619         UTF8, and the size of the output vector (ovecsize) is at least  2,  the         UTF8, and the size of the output vector (ovecsize) is at least  2,  the
# Line 4101  AUTHOR Line 4101  AUTHOR
4101    
4102  REVISION  REVISION
4103    
4104         Last updated: 31 October 2012         Last updated: 08 November 2012
4105         Copyright (c) 1997-2012 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
4106  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
4107    
4108    
4109  PCRECALLOUT(3)                                                  PCRECALLOUT(3)  PCRECALLOUT(3)                                                  PCRECALLOUT(3)
4110    
4111    
# Line 4313  REVISION Line 4313  REVISION
4313         Last updated: 24 June 2012         Last updated: 24 June 2012
4314         Copyright (c) 1997-2012 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
4315  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
4316    
4317    
4318  PCRECOMPAT(3)                                                    PCRECOMPAT(3)  PCRECOMPAT(3)                                                    PCRECOMPAT(3)
4319    
4320    
# Line 4491  REVISION Line 4491  REVISION
4491         Last updated: 25 August 2012         Last updated: 25 August 2012
4492         Copyright (c) 1997-2012 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.
4493  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
4494    
4495    
4496  PCREPATTERN(3)                                                  PCREPATTERN(3)  PCREPATTERN(3)                                                  PCREPATTERN(3)
4497    
4498    
# Line 4520  PCRE REGULAR EXPRESSION DETAILS Line 4520  PCRE REGULAR EXPRESSION DETAILS
4520         The original operation of PCRE was on strings of  one-byte  characters.         The original operation of PCRE was on strings of  one-byte  characters.
4521         However,  there  is  now also support for UTF-8 strings in the original         However,  there  is  now also support for UTF-8 strings in the original
4522         library, an extra library that supports  16-bit  and  UTF-16  character         library, an extra library that supports  16-bit  and  UTF-16  character
4523         strings, and an extra library that supports 32-bit and UTF-32 character         strings,  and a third library that supports 32-bit and UTF-32 character
4524         strings. To use these features, PCRE must be built to include appropri-         strings. To use these features, PCRE must be built to include appropri-
4525         ate  support. When using UTF strings you must either call the compiling         ate  support. When using UTF strings you must either call the compiling
4526         function with the PCRE_UTF8, PCRE_UTF16 or PCRE_UTF32  option,  or  the         function with the PCRE_UTF8, PCRE_UTF16, or PCRE_UTF32 option,  or  the
4527         pattern must start with one of these special sequences:         pattern must start with one of these special sequences:
4528    
4529           (*UTF8)           (*UTF8)
4530           (*UTF16)           (*UTF16)
4531           (*UTF32)           (*UTF32)
4532             (*UTF)
4533    
4534         Starting  a  pattern  with such a sequence is equivalent to setting the         (*UTF)  is  a  generic  sequence  that  can  be  used  with  any of the
4535         relevant option. This feature is not Perl-compatible. How setting a UTF         libraries.  Starting a pattern with such a sequence  is  equivalent  to
4536         mode  affects  pattern  matching  is mentioned in several places below.         setting  the  relevant option. This feature is not Perl-compatible. How
4537         There is also a summary of features in the pcreunicode page.         setting a UTF mode affects pattern matching  is  mentioned  in  several
4538           places  below.  There  is also a summary of features in the pcreunicode
4539           page.
4540    
4541         Another special sequence that may appear at the start of a  pattern  or         Another special sequence that may appear at the start of a  pattern  or
4542         in combination with (*UTF8) or (*UTF16) or (*UTF32) is:         in combination with (*UTF8), (*UTF16), (*UTF32) or (*UTF) is:
4543    
4544           (*UCP)           (*UCP)
4545    
# Line 4600  NEWLINE CONVENTIONS Line 4603  NEWLINE CONVENTIONS
4603         and that they must be in upper case.  If  more  than  one  of  them  is         and that they must be in upper case.  If  more  than  one  of  them  is
4604         present, the last one is used.         present, the last one is used.
4605    
4606         The  newline convention affects the interpretation of the dot metachar-         The  newline  convention affects where the circumflex and dollar asser-
4607         acter when PCRE_DOTALL is not set, and also the behaviour of  \N.  How-         tions are true. It also affects the interpretation of the dot metachar-
4608         ever,  it  does  not  affect  what  the  \R escape sequence matches. By         acter when PCRE_DOTALL is not set, and the behaviour of \N. However, it
4609         default, this is any Unicode newline sequence, for Perl  compatibility.         does not affect what the \R escape sequence matches. By  default,  this
4610         However,  this can be changed; see the description of \R in the section         is  any Unicode newline sequence, for Perl compatibility. However, this
4611         entitled "Newline sequences" below. A change of \R setting can be  com-         can be changed; see the description of \R in the section entitled "New-
4612         bined with a change of newline convention.         line  sequences"  below.  A change of \R setting can be combined with a
4613           change of newline convention.
4614    
4615    
4616  CHARACTERS AND METACHARACTERS  CHARACTERS AND METACHARACTERS
4617    
4618         A  regular  expression  is  a pattern that is matched against a subject         A regular expression is a pattern that is  matched  against  a  subject
4619         string from left to right. Most characters stand for  themselves  in  a         string  from  left  to right. Most characters stand for themselves in a
4620         pattern,  and  match  the corresponding characters in the subject. As a         pattern, and match the corresponding characters in the  subject.  As  a
4621         trivial example, the pattern         trivial example, the pattern
4622    
4623           The quick brown fox           The quick brown fox
4624    
4625         matches a portion of a subject string that is identical to itself. When         matches a portion of a subject string that is identical to itself. When
4626         caseless  matching is specified (the PCRE_CASELESS option), letters are         caseless matching is specified (the PCRE_CASELESS option), letters  are
4627         matched independently of case. In a UTF mode, PCRE  always  understands         matched  independently  of case. In a UTF mode, PCRE always understands
4628         the  concept  of case for characters whose values are less than 128, so         the concept of case for characters whose values are less than  128,  so
4629         caseless matching is always possible. For characters with  higher  val-         caseless  matching  is always possible. For characters with higher val-
4630         ues,  the concept of case is supported if PCRE is compiled with Unicode         ues, the concept of case is supported if PCRE is compiled with  Unicode
4631         property support, but not otherwise.   If  you  want  to  use  caseless         property  support,  but  not  otherwise.   If  you want to use caseless
4632         matching  for  characters  128  and above, you must ensure that PCRE is         matching for characters 128 and above, you must  ensure  that  PCRE  is
4633         compiled with Unicode property support as well as with UTF support.         compiled with Unicode property support as well as with UTF support.
4634    
4635         The power of regular expressions comes  from  the  ability  to  include         The  power  of  regular  expressions  comes from the ability to include
4636         alternatives  and  repetitions in the pattern. These are encoded in the         alternatives and repetitions in the pattern. These are encoded  in  the
4637         pattern by the use of metacharacters, which do not stand for themselves         pattern by the use of metacharacters, which do not stand for themselves
4638         but instead are interpreted in some special way.         but instead are interpreted in some special way.
4639    
4640         There  are  two different sets of metacharacters: those that are recog-         There are two different sets of metacharacters: those that  are  recog-
4641         nized anywhere in the pattern except within square brackets, and  those         nized  anywhere in the pattern except within square brackets, and those
4642         that  are  recognized  within square brackets. Outside square brackets,         that are recognized within square brackets.  Outside  square  brackets,
4643         the metacharacters are as follows:         the metacharacters are as follows:
4644    
4645           \      general escape character with several uses           \      general escape character with several uses
# Line 4654  CHARACTERS AND METACHARACTERS Line 4658  CHARACTERS AND METACHARACTERS
4658                  also "possessive quantifier"                  also "possessive quantifier"
4659           {      start min/max quantifier           {      start min/max quantifier
4660    
4661         Part of a pattern that is in square brackets  is  called  a  "character         Part  of  a  pattern  that is in square brackets is called a "character
4662         class". In a character class the only metacharacters are:         class". In a character class the only metacharacters are:
4663    
4664           \      general escape character           \      general escape character
# Line 4671  BACKSLASH Line 4675  BACKSLASH
4675    
4676         The backslash character has several uses. Firstly, if it is followed by         The backslash character has several uses. Firstly, if it is followed by
4677         a character that is not a number or a letter, it takes away any special         a character that is not a number or a letter, it takes away any special
4678         meaning  that  character  may  have. This use of backslash as an escape         meaning that character may have. This use of  backslash  as  an  escape
4679         character applies both inside and outside character classes.         character applies both inside and outside character classes.
4680    
4681         For example, if you want to match a * character, you write  \*  in  the         For  example,  if  you want to match a * character, you write \* in the
4682         pattern.   This  escaping  action  applies whether or not the following         pattern.  This escaping action applies whether  or  not  the  following
4683         character would otherwise be interpreted as a metacharacter, so  it  is         character  would  otherwise be interpreted as a metacharacter, so it is
4684         always  safe  to  precede  a non-alphanumeric with backslash to specify         always safe to precede a non-alphanumeric  with  backslash  to  specify
4685         that it stands for itself. In particular, if you want to match a  back-         that  it stands for itself. In particular, if you want to match a back-
4686         slash, you write \\.         slash, you write \\.
4687    
4688         In  a UTF mode, only ASCII numbers and letters have any special meaning         In a UTF mode, only ASCII numbers and letters have any special  meaning
4689         after a backslash. All other characters  (in  particular,  those  whose         after  a  backslash.  All  other characters (in particular, those whose
4690         codepoints are greater than 127) are treated as literals.         codepoints are greater than 127) are treated as literals.
4691    
4692         If  a pattern is compiled with the PCRE_EXTENDED option, white space in         If a pattern is compiled with the PCRE_EXTENDED option, white space  in
4693         the pattern (other than in a character class) and characters between  a         the  pattern (other than in a character class) and characters between a
4694         # outside a character class and the next newline are ignored. An escap-         # outside a character class and the next newline are ignored. An escap-
4695         ing backslash can be used to include a white space or  #  character  as         ing  backslash  can  be used to include a white space or # character as
4696         part of the pattern.         part of the pattern.
4697    
4698         If  you  want  to remove the special meaning from a sequence of charac-         If you want to remove the special meaning from a  sequence  of  charac-
4699         ters, you can do so by putting them between \Q and \E. This is  differ-         ters,  you can do so by putting them between \Q and \E. This is differ-
4700         ent  from  Perl  in  that  $  and  @ are handled as literals in \Q...\E         ent from Perl in that $ and  @  are  handled  as  literals  in  \Q...\E
4701         sequences in PCRE, whereas in Perl, $ and @ cause  variable  interpola-         sequences  in  PCRE, whereas in Perl, $ and @ cause variable interpola-
4702         tion. Note the following examples:         tion. Note the following examples:
4703    
4704           Pattern            PCRE matches   Perl matches           Pattern            PCRE matches   Perl matches
# Line 4704  BACKSLASH Line 4708  BACKSLASH
4708           \Qabc\$xyz\E       abc\$xyz       abc\$xyz           \Qabc\$xyz\E       abc\$xyz       abc\$xyz
4709           \Qabc\E\$\Qxyz\E   abc$xyz        abc$xyz           \Qabc\E\$\Qxyz\E   abc$xyz        abc$xyz
4710    
4711         The  \Q...\E  sequence  is recognized both inside and outside character         The \Q...\E sequence is recognized both inside  and  outside  character
4712         classes.  An isolated \E that is not preceded by \Q is ignored.  If  \Q         classes.   An  isolated \E that is not preceded by \Q is ignored. If \Q
4713         is  not followed by \E later in the pattern, the literal interpretation         is not followed by \E later in the pattern, the literal  interpretation
4714         continues to the end of the pattern (that is,  \E  is  assumed  at  the         continues  to  the  end  of  the pattern (that is, \E is assumed at the
4715         end).  If  the  isolated \Q is inside a character class, this causes an         end). If the isolated \Q is inside a character class,  this  causes  an
4716         error, because the character class is not terminated.         error, because the character class is not terminated.
4717    
4718     Non-printing characters     Non-printing characters
4719    
4720         A second use of backslash provides a way of encoding non-printing char-         A second use of backslash provides a way of encoding non-printing char-
4721         acters  in patterns in a visible manner. There is no restriction on the         acters in patterns in a visible manner. There is no restriction on  the
4722         appearance of non-printing characters, apart from the binary zero  that         appearance  of non-printing characters, apart from the binary zero that
4723         terminates  a  pattern,  but  when  a pattern is being prepared by text         terminates a pattern, but when a pattern  is  being  prepared  by  text
4724         editing, it is  often  easier  to  use  one  of  the  following  escape         editing,  it  is  often  easier  to  use  one  of  the following escape
4725         sequences than the binary character it represents:         sequences than the binary character it represents:
4726    
4727           \a        alarm, that is, the BEL character (hex 07)           \a        alarm, that is, the BEL character (hex 07)
# Line 4732  BACKSLASH Line 4736  BACKSLASH
4736           \x{hhh..} character with hex code hhh.. (non-JavaScript mode)           \x{hhh..} character with hex code hhh.. (non-JavaScript mode)
4737           \uhhhh    character with hex code hhhh (JavaScript mode only)           \uhhhh    character with hex code hhhh (JavaScript mode only)
4738    
4739         The  precise effect of \cx on ASCII characters is as follows: if x is a         The precise effect of \cx on ASCII characters is as follows: if x is  a
4740         lower case letter, it is converted to upper case. Then  bit  6  of  the         lower  case  letter,  it  is converted to upper case. Then bit 6 of the
4741         character (hex 40) is inverted. Thus \cA to \cZ become hex 01 to hex 1A         character (hex 40) is inverted. Thus \cA to \cZ become hex 01 to hex 1A
4742         (A is 41, Z is 5A), but \c{ becomes hex 3B ({ is 7B), and  \c;  becomes         (A  is  41, Z is 5A), but \c{ becomes hex 3B ({ is 7B), and \c; becomes
4743         hex  7B (; is 3B). If the data item (byte or 16-bit value) following \c         hex 7B (; is 3B). If the data item (byte or 16-bit value) following  \c
4744         has a value greater than 127, a compile-time error occurs.  This  locks         has  a  value greater than 127, a compile-time error occurs. This locks
4745         out non-ASCII characters in all modes.         out non-ASCII characters in all modes.
4746    
4747         The  \c  facility  was designed for use with ASCII characters, but with         The \c facility was designed for use with ASCII  characters,  but  with
4748         the extension to Unicode it is even less useful than it  once  was.  It         the  extension  to  Unicode it is even less useful than it once was. It
4749         is,  however,  recognized  when  PCRE is compiled in EBCDIC mode, where         is, however, recognized when PCRE is compiled  in  EBCDIC  mode,  where
4750         data items are always bytes. In this mode, all values are  valid  after         data  items  are always bytes. In this mode, all values are valid after
4751         \c.  If  the  next character is a lower case letter, it is converted to         \c. If the next character is a lower case letter, it  is  converted  to
4752         upper case. Then the 0xc0 bits of  the  byte  are  inverted.  Thus  \cA         upper  case.  Then  the  0xc0  bits  of the byte are inverted. Thus \cA
4753         becomes  hex  01, as in ASCII (A is C1), but because the EBCDIC letters         becomes hex 01, as in ASCII (A is C1), but because the  EBCDIC  letters
4754         are disjoint, \cZ becomes hex 29 (Z is E9), and other  characters  also         are  disjoint,  \cZ becomes hex 29 (Z is E9), and other characters also
4755         generate different values.         generate different values.
4756    
4757         By  default,  after  \x,  from  zero to two hexadecimal digits are read         By default, after \x, from zero to  two  hexadecimal  digits  are  read
4758         (letters can be in upper or lower case). Any number of hexadecimal dig-         (letters can be in upper or lower case). Any number of hexadecimal dig-
4759         its may appear between \x{ and }, but the character code is constrained         its may appear between \x{ and }, but the character code is constrained
4760         as follows:         as follows:
# Line 4762  BACKSLASH Line 4766  BACKSLASH
4766           32-bit non-UTF mode   less than 0x80000000           32-bit non-UTF mode   less than 0x80000000
4767           32-bit UTF-32 mode    less than 0x10ffff and a valid codepoint           32-bit UTF-32 mode    less than 0x10ffff and a valid codepoint
4768    
4769         Invalid Unicode codepoints are the range  0xd800  to  0xdfff  (the  so-         Invalid  Unicode  codepoints  are  the  range 0xd800 to 0xdfff (the so-
4770         called "surrogate" codepoints), and 0xffef.         called "surrogate" codepoints), and 0xffef.
4771    
4772         If  characters  other than hexadecimal digits appear between \x{ and },         If characters other than hexadecimal digits appear between \x{  and  },
4773         or if there is no terminating }, this form of escape is not recognized.         or if there is no terminating }, this form of escape is not recognized.
4774         Instead,  the  initial  \x  will  be interpreted as a basic hexadecimal         Instead, the initial \x will be  interpreted  as  a  basic  hexadecimal
4775         escape, with no following digits, giving a  character  whose  value  is         escape,  with  no  following  digits, giving a character whose value is
4776         zero.         zero.
4777    
4778         If  the  PCRE_JAVASCRIPT_COMPAT option is set, the interpretation of \x         If the PCRE_JAVASCRIPT_COMPAT option is set, the interpretation  of  \x
4779         is as just described only when it is followed by two  hexadecimal  dig-         is  as  just described only when it is followed by two hexadecimal dig-
4780         its.   Otherwise,  it  matches  a  literal "x" character. In JavaScript         its.  Otherwise, it matches a  literal  "x"  character.  In  JavaScript
4781         mode, support for code points greater than 256 is provided by \u, which         mode, support for code points greater than 256 is provided by \u, which
4782         must  be  followed  by  four hexadecimal digits; otherwise it matches a         must be followed by four hexadecimal digits;  otherwise  it  matches  a
4783         literal "u" character.  Character codes specified by \u  in  JavaScript         literal  "u"  character.  Character codes specified by \u in JavaScript
4784         mode  are  constrained in the same was as those specified by \x in non-         mode are constrained in the same was as those specified by \x  in  non-
4785         JavaScript mode.         JavaScript mode.
4786    
4787         Characters whose value is less than 256 can be defined by either of the         Characters whose value is less than 256 can be defined by either of the
4788         two  syntaxes for \x (or by \u in JavaScript mode). There is no differ-         two syntaxes for \x (or by \u in JavaScript mode). There is no  differ-
4789         ence in the way they are handled. For example, \xdc is exactly the same         ence in the way they are handled. For example, \xdc is exactly the same
4790         as \x{dc} (or \u00dc in JavaScript mode).         as \x{dc} (or \u00dc in JavaScript mode).
4791    
4792         After  \0  up  to two further octal digits are read. If there are fewer         After \0 up to two further octal digits are read. If  there  are  fewer
4793         than two digits, just  those  that  are  present  are  used.  Thus  the         than  two  digits,  just  those  that  are  present  are used. Thus the
4794         sequence \0\x\07 specifies two binary zeros followed by a BEL character         sequence \0\x\07 specifies two binary zeros followed by a BEL character
4795         (code value 7). Make sure you supply two digits after the initial  zero         (code  value 7). Make sure you supply two digits after the initial zero
4796         if the pattern character that follows is itself an octal digit.         if the pattern character that follows is itself an octal digit.
4797    
4798         The handling of a backslash followed by a digit other than 0 is compli-         The handling of a backslash followed by a digit other than 0 is compli-
4799         cated.  Outside a character class, PCRE reads it and any following dig-         cated.  Outside a character class, PCRE reads it and any following dig-
4800         its  as  a  decimal  number. If the number is less than 10, or if there         its as a decimal number. If the number is less than  10,  or  if  there
4801         have been at least that many previous capturing left parentheses in the         have been at least that many previous capturing left parentheses in the
4802         expression,  the  entire  sequence  is  taken  as  a  back reference. A         expression, the entire  sequence  is  taken  as  a  back  reference.  A
4803         description of how this works is given later, following the  discussion         description  of how this works is given later, following the discussion
4804         of parenthesized subpatterns.         of parenthesized subpatterns.
4805    
4806         Inside  a  character  class, or if the decimal number is greater than 9         Inside a character class, or if the decimal number is  greater  than  9
4807         and there have not been that many capturing subpatterns, PCRE  re-reads         and  there have not been that many capturing subpatterns, PCRE re-reads
4808         up to three octal digits following the backslash, and uses them to gen-         up to three octal digits following the backslash, and uses them to gen-
4809         erate a data character. Any subsequent digits stand for themselves. The         erate a data character. Any subsequent digits stand for themselves. The
4810         value  of  the  character  is constrained in the same way as characters         value of the character is constrained in the  same  way  as  characters
4811         specified in hexadecimal.  For example:         specified in hexadecimal.  For example:
4812    
4813           \040   is another way of writing an ASCII space           \040   is another way of writing an ASCII space
# Line 4821  BACKSLASH Line 4825  BACKSLASH
4825           \81    is either a back reference, or a binary zero           \81    is either a back reference, or a binary zero
4826                     followed by the two characters "8" and "1"                     followed by the two characters "8" and "1"
4827    
4828         Note that octal values of 100 or greater must not be  introduced  by  a         Note  that  octal  values of 100 or greater must not be introduced by a
4829         leading zero, because no more than three octal digits are ever read.         leading zero, because no more than three octal digits are ever read.
4830    
4831         All the sequences that define a single character value can be used both         All the sequences that define a single character value can be used both
4832         inside and outside character classes. In addition, inside  a  character         inside  and  outside character classes. In addition, inside a character
4833         class, \b is interpreted as the backspace character (hex 08).         class, \b is interpreted as the backspace character (hex 08).
4834    
4835         \N  is not allowed in a character class. \B, \R, and \X are not special         \N is not allowed in a character class. \B, \R, and \X are not  special
4836         inside a character class. Like  other  unrecognized  escape  sequences,         inside  a  character  class.  Like other unrecognized escape sequences,
4837         they  are  treated  as  the  literal  characters  "B",  "R", and "X" by         they are treated as  the  literal  characters  "B",  "R",  and  "X"  by
4838         default, but cause an error if the PCRE_EXTRA option is set. Outside  a         default,  but cause an error if the PCRE_EXTRA option is set. Outside a
4839         character class, these sequences have different meanings.         character class, these sequences have different meanings.
4840    
4841     Unsupported escape sequences     Unsupported escape sequences
4842    
4843         In  Perl, the sequences \l, \L, \u, and \U are recognized by its string         In Perl, the sequences \l, \L, \u, and \U are recognized by its  string
4844         handler and used  to  modify  the  case  of  following  characters.  By         handler  and  used  to  modify  the  case  of  following characters. By
4845         default,  PCRE does not support these escape sequences. However, if the         default, PCRE does not support these escape sequences. However, if  the
4846         PCRE_JAVASCRIPT_COMPAT option is set, \U matches a "U"  character,  and         PCRE_JAVASCRIPT_COMPAT  option  is set, \U matches a "U" character, and
4847         \u can be used to define a character by code point, as described in the         \u can be used to define a character by code point, as described in the
4848         previous section.         previous section.
4849    
4850     Absolute and relative back references     Absolute and relative back references
4851    
4852         The sequence \g followed by an unsigned or a negative  number,  option-         The  sequence  \g followed by an unsigned or a negative number, option-
4853         ally  enclosed  in braces, is an absolute or relative back reference. A         ally enclosed in braces, is an absolute or relative back  reference.  A
4854         named back reference can be coded as \g{name}. Back references are dis-         named back reference can be coded as \g{name}. Back references are dis-
4855         cussed later, following the discussion of parenthesized subpatterns.         cussed later, following the discussion of parenthesized subpatterns.
4856    
4857     Absolute and relative subroutine calls     Absolute and relative subroutine calls
4858    
4859         For  compatibility with Oniguruma, the non-Perl syntax \g followed by a         For compatibility with Oniguruma, the non-Perl syntax \g followed by  a
4860         name or a number enclosed either in angle brackets or single quotes, is         name or a number enclosed either in angle brackets or single quotes, is
4861         an  alternative  syntax for referencing a subpattern as a "subroutine".         an alternative syntax for referencing a subpattern as  a  "subroutine".
4862         Details are discussed later.   Note  that  \g{...}  (Perl  syntax)  and         Details  are  discussed  later.   Note  that  \g{...} (Perl syntax) and
4863         \g<...>  (Oniguruma  syntax)  are  not synonymous. The former is a back         \g<...> (Oniguruma syntax) are not synonymous. The  former  is  a  back
4864         reference; the latter is a subroutine call.         reference; the latter is a subroutine call.
4865    
4866     Generic character types     Generic character types
# Line 4875  BACKSLASH Line 4879  BACKSLASH
4879           \W     any "non-word" character           \W     any "non-word" character
4880    
4881         There is also the single sequence \N, which matches a non-newline char-         There is also the single sequence \N, which matches a non-newline char-
4882         acter.   This  is the same as the "." metacharacter when PCRE_DOTALL is         acter.  This is the same as the "." metacharacter when  PCRE_DOTALL  is
4883         not set. Perl also uses \N to match characters by name; PCRE  does  not         not  set.  Perl also uses \N to match characters by name; PCRE does not
4884         support this.         support this.
4885    
4886         Each  pair of lower and upper case escape sequences partitions the com-         Each pair of lower and upper case escape sequences partitions the  com-
4887         plete set of characters into two disjoint  sets.  Any  given  character         plete  set  of  characters  into two disjoint sets. Any given character
4888         matches  one, and only one, of each pair. The sequences can appear both         matches one, and only one, of each pair. The sequences can appear  both
4889         inside and outside character classes. They each match one character  of         inside  and outside character classes. They each match one character of
4890         the  appropriate  type.  If the current matching point is at the end of         the appropriate type. If the current matching point is at  the  end  of
4891         the subject string, all of them fail, because there is no character  to         the  subject string, all of them fail, because there is no character to
4892         match.         match.
4893    
4894         For  compatibility  with Perl, \s does not match the VT character (code         For compatibility with Perl, \s does not match the VT  character  (code
4895         11).  This makes it different from the the POSIX "space" class. The  \s         11).   This makes it different from the the POSIX "space" class. The \s
4896         characters  are  HT  (9), LF (10), FF (12), CR (13), and space (32). If         characters are HT (9), LF (10), FF (12), CR (13), and  space  (32).  If
4897         "use locale;" is included in a Perl script, \s may match the VT charac-         "use locale;" is included in a Perl script, \s may match the VT charac-
4898         ter. In PCRE, it never does.         ter. In PCRE, it never does.
4899    
4900         A  "word"  character is an underscore or any character that is a letter         A "word" character is an underscore or any character that is  a  letter
4901         or digit.  By default, the definition of letters  and  digits  is  con-         or  digit.   By  default,  the definition of letters and digits is con-
4902         trolled  by PCRE's low-valued character tables, and may vary if locale-         trolled by PCRE's low-valued character tables, and may vary if  locale-
4903         specific matching is taking place (see "Locale support" in the  pcreapi         specific  matching is taking place (see "Locale support" in the pcreapi
4904         page).  For  example,  in  a French locale such as "fr_FR" in Unix-like         page). For example, in a French locale such  as  "fr_FR"  in  Unix-like
4905         systems, or "french" in Windows, some character codes greater than  128         systems,  or "french" in Windows, some character codes greater than 128
4906         are  used  for  accented letters, and these are then matched by \w. The         are used for accented letters, and these are then matched  by  \w.  The
4907         use of locales with Unicode is discouraged.         use of locales with Unicode is discouraged.
4908    
4909         By default, in a UTF mode, characters  with  values  greater  than  128         By  default,  in  a  UTF  mode, characters with values greater than 128
4910         never  match  \d,  \s,  or  \w,  and always match \D, \S, and \W. These         never match \d, \s, or \w, and always  match  \D,  \S,  and  \W.  These
4911         sequences retain their original meanings from before  UTF  support  was         sequences  retain  their  original meanings from before UTF support was
4912         available,  mainly for efficiency reasons. However, if PCRE is compiled         available, mainly for efficiency reasons. However, if PCRE is  compiled
4913         with Unicode property support, and the PCRE_UCP option is set, the  be-         with  Unicode property support, and the PCRE_UCP option is set, the be-
4914         haviour  is  changed  so  that Unicode properties are used to determine         haviour is changed so that Unicode properties  are  used  to  determine
4915         character types, as follows:         character types, as follows:
4916    
4917           \d  any character that \p{Nd} matches (decimal digit)           \d  any character that \p{Nd} matches (decimal digit)
4918           \s  any character that \p{Z} matches, plus HT, LF, FF, CR           \s  any character that \p{Z} matches, plus HT, LF, FF, CR
4919           \w  any character that \p{L} or \p{N} matches, plus underscore           \w  any character that \p{L} or \p{N} matches, plus underscore
4920    
4921         The upper case escapes match the inverse sets of characters. Note  that         The  upper case escapes match the inverse sets of characters. Note that
4922         \d  matches  only decimal digits, whereas \w matches any Unicode digit,         \d matches only decimal digits, whereas \w matches any  Unicode  digit,
4923         as well as any Unicode letter, and underscore. Note also that  PCRE_UCP         as  well as any Unicode letter, and underscore. Note also that PCRE_UCP
4924         affects  \b,  and  \B  because  they are defined in terms of \w and \W.         affects \b, and \B because they are defined in  terms  of  \w  and  \W.
4925         Matching these sequences is noticeably slower when PCRE_UCP is set.         Matching these sequences is noticeably slower when PCRE_UCP is set.
4926    
4927         The sequences \h, \H, \v, and \V are features that were added  to  Perl         The  sequences  \h, \H, \v, and \V are features that were added to Perl
4928         at  release  5.10. In contrast to the other sequences, which match only         at release 5.10. In contrast to the other sequences, which  match  only
4929         ASCII characters by default, these  always  match  certain  high-valued         ASCII  characters  by  default,  these always match certain high-valued
4930         codepoints,  whether or not PCRE_UCP is set. The horizontal space char-         codepoints, whether or not PCRE_UCP is set. The horizontal space  char-
4931         acters are:         acters are:
4932    
4933           U+0009     Horizontal tab (HT)           U+0009     Horizontal tab (HT)
# Line 4961  BACKSLASH Line 4965  BACKSLASH
4965    
4966     Newline sequences     Newline sequences
4967    
4968         Outside  a  character class, by default, the escape sequence \R matches         Outside a character class, by default, the escape sequence  \R  matches
4969         any Unicode newline sequence. In 8-bit non-UTF-8 mode \R is  equivalent         any  Unicode newline sequence. In 8-bit non-UTF-8 mode \R is equivalent
4970         to the following:         to the following:
4971    
4972           (?>\r\n|\n|\x0b|\f|\r|\x85)           (?>\r\n|\n|\x0b|\f|\r|\x85)
4973    
4974         This  is  an  example  of an "atomic group", details of which are given         This is an example of an "atomic group", details  of  which  are  given
4975         below.  This particular group matches either the two-character sequence         below.  This particular group matches either the two-character sequence
4976         CR  followed  by  LF,  or  one  of  the single characters LF (linefeed,         CR followed by LF, or  one  of  the  single  characters  LF  (linefeed,
4977         U+000A), VT (vertical tab, U+000B), FF (form feed,  U+000C),  CR  (car-         U+000A),  VT  (vertical  tab, U+000B), FF (form feed, U+000C), CR (car-
4978         riage  return,  U+000D),  or NEL (next line, U+0085). The two-character         riage return, U+000D), or NEL (next line,  U+0085).  The  two-character
4979         sequence is treated as a single unit that cannot be split.         sequence is treated as a single unit that cannot be split.
4980    
4981         In other modes, two additional characters whose codepoints are  greater         In  other modes, two additional characters whose codepoints are greater
4982         than 255 are added: LS (line separator, U+2028) and PS (paragraph sepa-         than 255 are added: LS (line separator, U+2028) and PS (paragraph sepa-
4983         rator, U+2029).  Unicode character property support is not  needed  for         rator,  U+2029).   Unicode character property support is not needed for
4984         these characters to be recognized.         these characters to be recognized.
4985    
4986         It is possible to restrict \R to match only CR, LF, or CRLF (instead of         It is possible to restrict \R to match only CR, LF, or CRLF (instead of
4987         the complete set  of  Unicode  line  endings)  by  setting  the  option         the  complete  set  of  Unicode  line  endings)  by  setting the option
4988         PCRE_BSR_ANYCRLF either at compile time or when the pattern is matched.         PCRE_BSR_ANYCRLF either at compile time or when the pattern is matched.
4989         (BSR is an abbrevation for "backslash R".) This can be made the default         (BSR is an abbrevation for "backslash R".) This can be made the default
4990         when  PCRE  is  built;  if this is the case, the other behaviour can be         when PCRE is built; if this is the case, the  other  behaviour  can  be
4991         requested via the PCRE_BSR_UNICODE option.   It  is  also  possible  to         requested  via  the  PCRE_BSR_UNICODE  option.   It is also possible to
4992         specify  these  settings  by  starting a pattern string with one of the         specify these settings by starting a pattern string  with  one  of  the
4993         following sequences:         following sequences:
4994    
4995           (*BSR_ANYCRLF)   CR, LF, or CRLF only           (*BSR_ANYCRLF)   CR, LF, or CRLF only
4996           (*BSR_UNICODE)   any Unicode newline sequence           (*BSR_UNICODE)   any Unicode newline sequence
4997    
4998         These override the default and the options given to the compiling func-         These override the default and the options given to the compiling func-
4999         tion,  but  they  can  themselves  be  overridden by options given to a         tion, but they can themselves be  overridden  by  options  given  to  a
5000         matching function. Note that these  special  settings,  which  are  not         matching  function.  Note  that  these  special settings, which are not
5001         Perl-compatible,  are  recognized  only at the very start of a pattern,         Perl-compatible, are recognized only at the very start  of  a  pattern,
5002         and that they must be in upper case.  If  more  than  one  of  them  is         and  that  they  must  be  in  upper  case. If more than one of them is
5003         present,  the  last  one is used. They can be combined with a change of         present, the last one is used. They can be combined with  a  change  of
5004         newline convention; for example, a pattern can start with:         newline convention; for example, a pattern can start with:
5005    
5006           (*ANY)(*BSR_ANYCRLF)           (*ANY)(*BSR_ANYCRLF)
5007    
5008         They can also be combined  with  the  (*UTF8),  (*UTF16),  (*UTF32)  or         They  can also be combined with the (*UTF8), (*UTF16), (*UTF32), (*UTF)
5009         (*UCP) special sequences. Inside a character class, \R is treated as an         or (*UCP) special sequences. Inside a character class, \R is treated as
5010         unrecognized escape sequence, and so matches the letter "R" by default,         an  unrecognized  escape  sequence,  and  so  matches the letter "R" by
5011         but causes an error if PCRE_EXTRA is set.         default, but causes an error if PCRE_EXTRA is set.
5012    
5013     Unicode character properties     Unicode character properties
5014    
5015         When PCRE is built with Unicode character property support, three addi-         When PCRE is built with Unicode character property support, three addi-
5016         tional escape sequences that match characters with specific  properties         tional  escape sequences that match characters with specific properties
5017         are  available.   When  in 8-bit non-UTF-8 mode, these sequences are of         are available.  When in 8-bit non-UTF-8 mode, these  sequences  are  of
5018         course limited to testing characters whose  codepoints  are  less  than         course  limited  to  testing  characters whose codepoints are less than
5019         256, but they do work in this mode.  The extra escape sequences are:         256, but they do work in this mode.  The extra escape sequences are:
5020    
5021           \p{xx}   a character with the xx property           \p{xx}   a character with the xx property
5022           \P{xx}   a character without the xx property           \P{xx}   a character without the xx property
5023           \X       a Unicode extended grapheme cluster           \X       a Unicode extended grapheme cluster
5024    
5025         The  property  names represented by xx above are limited to the Unicode         The property names represented by xx above are limited to  the  Unicode
5026         script names, the general category properties, "Any", which matches any         script names, the general category properties, "Any", which matches any
5027         character   (including  newline),  and  some  special  PCRE  properties         character  (including  newline),  and  some  special  PCRE   properties
5028         (described in the next section).  Other Perl properties such as  "InMu-         (described  in the next section).  Other Perl properties such as "InMu-
5029         sicalSymbols"  are  not  currently supported by PCRE. Note that \P{Any}         sicalSymbols" are not currently supported by PCRE.  Note  that  \P{Any}
5030         does not match any characters, so always causes a match failure.         does not match any characters, so always causes a match failure.
5031    
5032         Sets of Unicode characters are defined as belonging to certain scripts.         Sets of Unicode characters are defined as belonging to certain scripts.
5033         A  character from one of these sets can be matched using a script name.         A character from one of these sets can be matched using a script  name.
5034         For example:         For example:
5035    
5036           \p{Greek}           \p{Greek}
5037           \P{Han}           \P{Han}
5038    
5039         Those that are not part of an identified script are lumped together  as         Those  that are not part of an identified script are lumped together as
5040         "Common". The current list of scripts is:         "Common". The current list of scripts is:
5041    
5042         Arabic,  Armenian,  Avestan, Balinese, Bamum, Batak, Bengali, Bopomofo,         Arabic, Armenian, Avestan, Balinese, Bamum, Batak,  Bengali,  Bopomofo,
5043         Brahmi, Braille, Buginese, Buhid, Canadian_Aboriginal, Carian,  Chakma,         Brahmi,  Braille, Buginese, Buhid, Canadian_Aboriginal, Carian, Chakma,
5044         Cham,  Cherokee, Common, Coptic, Cuneiform, Cypriot, Cyrillic, Deseret,         Cham, Cherokee, Common, Coptic, Cuneiform, Cypriot, Cyrillic,  Deseret,
5045         Devanagari,  Egyptian_Hieroglyphs,  Ethiopic,   Georgian,   Glagolitic,         Devanagari,   Egyptian_Hieroglyphs,   Ethiopic,  Georgian,  Glagolitic,
5046         Gothic,  Greek, Gujarati, Gurmukhi, Han, Hangul, Hanunoo, Hebrew, Hira-         Gothic, Greek, Gujarati, Gurmukhi, Han, Hangul, Hanunoo, Hebrew,  Hira-
5047         gana,  Imperial_Aramaic,  Inherited,  Inscriptional_Pahlavi,   Inscrip-         gana,   Imperial_Aramaic,  Inherited,  Inscriptional_Pahlavi,  Inscrip-
5048         tional_Parthian,   Javanese,   Kaithi,   Kannada,  Katakana,  Kayah_Li,         tional_Parthian,  Javanese,  Kaithi,   Kannada,   Katakana,   Kayah_Li,
5049         Kharoshthi, Khmer, Lao, Latin, Lepcha, Limbu, Linear_B,  Lisu,  Lycian,         Kharoshthi,  Khmer,  Lao, Latin, Lepcha, Limbu, Linear_B, Lisu, Lycian,
5050         Lydian,    Malayalam,    Mandaic,    Meetei_Mayek,    Meroitic_Cursive,         Lydian,    Malayalam,    Mandaic,    Meetei_Mayek,    Meroitic_Cursive,
5051         Meroitic_Hieroglyphs,  Miao,  Mongolian,  Myanmar,  New_Tai_Lue,   Nko,         Meroitic_Hieroglyphs,   Miao,  Mongolian,  Myanmar,  New_Tai_Lue,  Nko,
5052         Ogham,    Old_Italic,   Old_Persian,   Old_South_Arabian,   Old_Turkic,         Ogham,   Old_Italic,   Old_Persian,   Old_South_Arabian,    Old_Turkic,
5053         Ol_Chiki, Oriya, Osmanya, Phags_Pa, Phoenician, Rejang, Runic,  Samari-         Ol_Chiki,  Oriya, Osmanya, Phags_Pa, Phoenician, Rejang, Runic, Samari-
5054         tan,  Saurashtra,  Sharada,  Shavian, Sinhala, Sora_Sompeng, Sundanese,         tan, Saurashtra, Sharada, Shavian,  Sinhala,  Sora_Sompeng,  Sundanese,
5055         Syloti_Nagri, Syriac, Tagalog, Tagbanwa,  Tai_Le,  Tai_Tham,  Tai_Viet,         Syloti_Nagri,  Syriac,  Tagalog,  Tagbanwa, Tai_Le, Tai_Tham, Tai_Viet,
5056         Takri,  Tamil,  Telugu, Thaana, Thai, Tibetan, Tifinagh, Ugaritic, Vai,         Takri, Tamil, Telugu, Thaana, Thai, Tibetan, Tifinagh,  Ugaritic,  Vai,
5057         Yi.         Yi.
5058    
5059         Each character has exactly one Unicode general category property, spec-         Each character has exactly one Unicode general category property, spec-
5060         ified  by a two-letter abbreviation. For compatibility with Perl, nega-         ified by a two-letter abbreviation. For compatibility with Perl,  nega-
5061         tion can be specified by including a  circumflex  between  the  opening         tion  can  be  specified  by including a circumflex between the opening
5062         brace  and  the  property  name.  For  example,  \p{^Lu} is the same as         brace and the property name.  For  example,  \p{^Lu}  is  the  same  as
5063         \P{Lu}.         \P{Lu}.
5064    
5065         If only one letter is specified with \p or \P, it includes all the gen-         If only one letter is specified with \p or \P, it includes all the gen-
5066         eral  category properties that start with that letter. In this case, in         eral category properties that start with that letter. In this case,  in
5067         the absence of negation, the curly brackets in the escape sequence  are         the  absence of negation, the curly brackets in the escape sequence are
5068         optional; these two examples have the same effect:         optional; these two examples have the same effect:
5069    
5070           \p{L}           \p{L}
# Line 5112  BACKSLASH Line 5116  BACKSLASH
5116           Zp    Paragraph separator           Zp    Paragraph separator
5117           Zs    Space separator           Zs    Space separator
5118    
5119         The  special property L& is also supported: it matches a character that         The special property L& is also supported: it matches a character  that
5120         has the Lu, Ll, or Lt property, in other words, a letter  that  is  not         has  the  Lu,  Ll, or Lt property, in other words, a letter that is not
5121         classified as a modifier or "other".         classified as a modifier or "other".
5122    
5123         The  Cs  (Surrogate)  property  applies only to characters in the range         The Cs (Surrogate) property applies only to  characters  in  the  range
5124         U+D800 to U+DFFF. Such characters are not valid in Unicode strings  and         U+D800  to U+DFFF. Such characters are not valid in Unicode strings and
5125         so  cannot  be  tested  by  PCRE, unless UTF validity checking has been         so cannot be tested by PCRE, unless  UTF  validity  checking  has  been
5126         turned    off    (see    the    discussion    of    PCRE_NO_UTF8_CHECK,         turned    off    (see    the    discussion    of    PCRE_NO_UTF8_CHECK,
5127         PCRE_NO_UTF16_CHECK  and PCRE_NO_UTF32_CHECK in the pcreapi page). Perl         PCRE_NO_UTF16_CHECK and PCRE_NO_UTF32_CHECK in the pcreapi page).  Perl
5128         does not support the Cs property.         does not support the Cs property.
5129    
5130         The long synonyms for  property  names  that  Perl  supports  (such  as         The  long  synonyms  for  property  names  that  Perl supports (such as
5131         \p{Letter})  are  not  supported by PCRE, nor is it permitted to prefix         \p{Letter}) are not supported by PCRE, nor is it  permitted  to  prefix
5132         any of these properties with "Is".         any of these properties with "Is".
5133    
5134         No character that is in the Unicode table has the Cn (unassigned) prop-         No character that is in the Unicode table has the Cn (unassigned) prop-
5135         erty.  Instead, this property is assumed for any code point that is not         erty.  Instead, this property is assumed for any code point that is not
5136         in the Unicode table.         in the Unicode table.
5137    
5138         Specifying caseless matching does not affect  these  escape  sequences.         Specifying  caseless  matching  does not affect these escape sequences.
5139         For example, \p{Lu} always matches only upper case letters.         For example, \p{Lu} always matches only upper case letters.
5140    
5141         Matching  characters  by Unicode property is not fast, because PCRE has         Matching characters by Unicode property is not fast, because  PCRE  has
5142         to do a multistage table lookup in order to find  a  character's  prop-         to  do  a  multistage table lookup in order to find a character's prop-
5143         erty. That is why the traditional escape sequences such as \d and \w do         erty. That is why the traditional escape sequences such as \d and \w do
5144         not use Unicode properties in PCRE by default, though you can make them         not use Unicode properties in PCRE by default, though you can make them
5145         do  so  by  setting the PCRE_UCP option or by starting the pattern with         do so by setting the PCRE_UCP option or by starting  the  pattern  with
5146         (*UCP).         (*UCP).
5147    
5148     Extended grapheme clusters     Extended grapheme clusters
5149    
5150         The \X escape matches any number of Unicode  characters  that  form  an         The  \X  escape  matches  any number of Unicode characters that form an
5151         "extended grapheme cluster", and treats the sequence as an atomic group         "extended grapheme cluster", and treats the sequence as an atomic group
5152         (see below).  Up to and including release 8.31, PCRE  matched  an  ear-         (see  below).   Up  to and including release 8.31, PCRE matched an ear-
5153         lier, simpler definition that was equivalent to         lier, simpler definition that was equivalent to
5154    
5155           (?>\PM\pM*)           (?>\PM\pM*)
5156    
5157         That  is,  it matched a character without the "mark" property, followed         That is, it matched a character without the "mark"  property,  followed
5158         by zero or more characters with the "mark"  property.  Characters  with         by  zero  or  more characters with the "mark" property. Characters with
5159         the  "mark"  property are typically non-spacing accents that affect the         the "mark" property are typically non-spacing accents that  affect  the
5160         preceding character.         preceding character.
5161    
5162         This simple definition was extended in Unicode to include more  compli-         This  simple definition was extended in Unicode to include more compli-
5163         cated  kinds of composite character by giving each character a grapheme         cated kinds of composite character by giving each character a  grapheme
5164         breaking property, and creating rules  that  use  these  properties  to         breaking  property,  and  creating  rules  that use these properties to
5165         define  the  boundaries  of  extended grapheme clusters. In releases of         define the boundaries of extended grapheme  clusters.  In  releases  of
5166         PCRE later than 8.31, \X matches one of these clusters.         PCRE later than 8.31, \X matches one of these clusters.
5167    
5168         \X always matches at least one character. Then it  decides  whether  to         \X  always  matches  at least one character. Then it decides whether to
5169         add additional characters according to the following rules for ending a         add additional characters according to the following rules for ending a
5170         cluster:         cluster:
5171    
5172         1. End at the end of the subject string.         1. End at the end of the subject string.
5173    
5174         2. Do not end between CR and LF; otherwise end after any control  char-         2.  Do not end between CR and LF; otherwise end after any control char-
5175         acter.         acter.
5176    
5177         3.  Do  not  break  Hangul (a Korean script) syllable sequences. Hangul         3. Do not break Hangul (a Korean  script)  syllable  sequences.  Hangul
5178         characters are of five types: L, V, T, LV, and LVT. An L character  may         characters  are of five types: L, V, T, LV, and LVT. An L character may
5179         be  followed by an L, V, LV, or LVT character; an LV or V character may         be followed by an L, V, LV, or LVT character; an LV or V character  may
5180         be followed by a V or T character; an LVT or T character may be follwed         be followed by a V or T character; an LVT or T character may be follwed
5181         only by a T character.         only by a T character.
5182    
5183         4.  Do not end before extending characters or spacing marks. Characters         4. Do not end before extending characters or spacing marks.  Characters
5184         with the "mark" property always have  the  "extend"  grapheme  breaking         with  the  "mark"  property  always have the "extend" grapheme breaking
5185         property.         property.
5186    
5187         5. Do not end after prepend characters.         5. Do not end after prepend characters.
# Line 5186  BACKSLASH Line 5190  BACKSLASH
5190    
5191     PCRE's additional properties     PCRE's additional properties
5192    
5193         As  well  as the standard Unicode properties described above, PCRE sup-         As well as the standard Unicode properties described above,  PCRE  sup-
5194         ports four more that make it possible  to  convert  traditional  escape         ports  four  more  that  make it possible to convert traditional escape
5195         sequences  such as \w and \s and POSIX character classes to use Unicode         sequences such as \w and \s and POSIX character classes to use  Unicode
5196         properties. PCRE uses these non-standard,  non-Perl  properties  inter-         properties.  PCRE  uses  these non-standard, non-Perl properties inter-
5197         nally when PCRE_UCP is set. They are:         nally when PCRE_UCP is set. They are:
5198    
5199           Xan   Any alphanumeric character           Xan   Any alphanumeric character
# Line 5197  BACKSLASH Line 5201  BACKSLASH
5201           Xsp   Any Perl space character           Xsp   Any Perl space character
5202           Xwd   Any Perl "word" character           Xwd   Any Perl "word" character
5203    
5204         Xan  matches  characters that have either the L (letter) or the N (num-         Xan matches characters that have either the L (letter) or the  N  (num-
5205         ber) property. Xps matches the characters tab, linefeed, vertical  tab,         ber)  property. Xps matches the characters tab, linefeed, vertical tab,
5206         form  feed,  or carriage return, and any other character that has the Z         form feed, or carriage return, and any other character that has  the  Z
5207         (separator) property.  Xsp is the same as Xps, except that vertical tab         (separator) property.  Xsp is the same as Xps, except that vertical tab
5208         is excluded. Xwd matches the same characters as Xan, plus underscore.         is excluded. Xwd matches the same characters as Xan, plus underscore.
5209    
5210     Resetting the match start     Resetting the match start
5211    
5212         The  escape sequence \K causes any previously matched characters not to         The escape sequence \K causes any previously matched characters not  to
5213         be included in the final matched sequence. For example, the pattern:         be included in the final matched sequence. For example, the pattern:
5214    
5215           foo\Kbar           foo\Kbar
5216    
5217         matches "foobar", but reports that it has matched "bar".  This  feature         matches  "foobar",  but reports that it has matched "bar". This feature
5218         is  similar  to  a lookbehind assertion (described below).  However, in         is similar to a lookbehind assertion (described  below).   However,  in
5219         this case, the part of the subject before the real match does not  have         this  case, the part of the subject before the real match does not have
5220         to  be of fixed length, as lookbehind assertions do. The use of \K does         to be of fixed length, as lookbehind assertions do. The use of \K  does
5221         not interfere with the setting of captured  substrings.   For  example,         not  interfere  with  the setting of captured substrings.  For example,
5222         when the pattern         when the pattern
5223    
5224           (foo)\Kbar           (foo)\Kbar
5225    
5226         matches "foobar", the first substring is still set to "foo".         matches "foobar", the first substring is still set to "foo".
5227    
5228         Perl  documents  that  the  use  of  \K  within assertions is "not well         Perl documents that the use  of  \K  within  assertions  is  "not  well
5229         defined". In PCRE, \K is acted upon  when  it  occurs  inside  positive         defined".  In  PCRE,  \K  is  acted upon when it occurs inside positive
5230         assertions, but is ignored in negative assertions.         assertions, but is ignored in negative assertions.
5231    
5232     Simple assertions     Simple assertions
5233    
5234         The  final use of backslash is for certain simple assertions. An asser-         The final use of backslash is for certain simple assertions. An  asser-
5235         tion specifies a condition that has to be met at a particular point  in         tion  specifies a condition that has to be met at a particular point in
5236         a  match, without consuming any characters from the subject string. The         a match, without consuming any characters from the subject string.  The
5237         use of subpatterns for more complicated assertions is described  below.         use  of subpatterns for more complicated assertions is described below.
5238         The backslashed assertions are:         The backslashed assertions are:
5239    
5240           \b     matches at a word boundary           \b     matches at a word boundary
# Line 5241  BACKSLASH Line 5245  BACKSLASH
5245           \z     matches only at the end of the subject           \z     matches only at the end of the subject
5246           \G     matches at the first matching position in the subject           \G     matches at the first matching position in the subject
5247    
5248         Inside  a  character  class, \b has a different meaning; it matches the         Inside a character class, \b has a different meaning;  it  matches  the
5249         backspace character. If any other of  these  assertions  appears  in  a         backspace  character.  If  any  other  of these assertions appears in a
5250         character  class, by default it matches the corresponding literal char-         character class, by default it matches the corresponding literal  char-
5251         acter  (for  example,  \B  matches  the  letter  B).  However,  if  the         acter  (for  example,  \B  matches  the  letter  B).  However,  if  the
5252         PCRE_EXTRA  option is set, an "invalid escape sequence" error is gener-         PCRE_EXTRA option is set, an "invalid escape sequence" error is  gener-
5253         ated instead.         ated instead.
5254    
5255         A word boundary is a position in the subject string where  the  current         A  word  boundary is a position in the subject string where the current
5256         character  and  the previous character do not both match \w or \W (i.e.         character and the previous character do not both match \w or  \W  (i.e.
5257         one matches \w and the other matches \W), or the start or  end  of  the         one  matches  \w  and the other matches \W), or the start or end of the
5258         string  if  the  first or last character matches \w, respectively. In a         string if the first or last character matches \w,  respectively.  In  a
5259         UTF mode, the meanings of \w and \W  can  be  changed  by  setting  the         UTF  mode,  the  meanings  of  \w  and \W can be changed by setting the
5260         PCRE_UCP  option. When this is done, it also affects \b and \B. Neither         PCRE_UCP option. When this is done, it also affects \b and \B.  Neither
5261         PCRE nor Perl has a separate "start of word" or "end of  word"  metase-         PCRE  nor  Perl has a separate "start of word" or "end of word" metase-
5262         quence.  However,  whatever follows \b normally determines which it is.         quence. However, whatever follows \b normally determines which  it  is.
5263         For example, the fragment \ba matches "a" at the start of a word.         For example, the fragment \ba matches "a" at the start of a word.
5264    
5265         The \A, \Z, and \z assertions differ from  the  traditional  circumflex         The  \A,  \Z,  and \z assertions differ from the traditional circumflex
5266         and dollar (described in the next section) in that they only ever match         and dollar (described in the next section) in that they only ever match
5267         at the very start and end of the subject string, whatever  options  are         at  the  very start and end of the subject string, whatever options are
5268         set.  Thus,  they are independent of multiline mode. These three asser-         set. Thus, they are independent of multiline mode. These  three  asser-
5269         tions are not affected by the PCRE_NOTBOL or PCRE_NOTEOL options, which         tions are not affected by the PCRE_NOTBOL or PCRE_NOTEOL options, which
5270         affect  only the behaviour of the circumflex and dollar metacharacters.         affect only the behaviour of the circumflex and dollar  metacharacters.
5271         However, if the startoffset argument of pcre_exec() is non-zero,  indi-         However,  if the startoffset argument of pcre_exec() is non-zero, indi-
5272         cating that matching is to start at a point other than the beginning of         cating that matching is to start at a point other than the beginning of
5273         the subject, \A can never match. The difference between \Z  and  \z  is         the  subject,  \A  can never match. The difference between \Z and \z is
5274         that \Z matches before a newline at the end of the string as well as at         that \Z matches before a newline at the end of the string as well as at
5275         the very end, whereas \z matches only at the end.         the very end, whereas \z matches only at the end.
5276