/[pcre]/code/trunk/doc/pcre.txt
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revision 545 by ph10, Wed Jun 16 10:51:15 2010 UTC revision 548 by ph10, Fri Jun 25 14:42:00 2010 UTC
# Line 1482  COMPILATION ERROR CODES Line 1482  COMPILATION ERROR CODES
1482           50  [this code is not in use]           50  [this code is not in use]
1483           51  octal value is greater than \377 (not in UTF-8 mode)           51  octal value is greater than \377 (not in UTF-8 mode)
1484           52  internal error: overran compiling workspace           52  internal error: overran compiling workspace
1485           53  internal  error:  previously-checked  referenced  subpattern  not           53  internal error: previously-checked referenced subpattern
1486         found                 not found
1487           54  DEFINE group contains more than one branch           54  DEFINE group contains more than one branch
1488           55  repeating a DEFINE group is not allowed           55  repeating a DEFINE group is not allowed
1489           56  inconsistent NEWLINE options           56  inconsistent NEWLINE options
# Line 1496  COMPILATION ERROR CODES Line 1496  COMPILATION ERROR CODES
1496           62  subpattern name expected           62  subpattern name expected
1497           63  digit expected after (?+           63  digit expected after (?+
1498           64  ] is an invalid data character in JavaScript compatibility mode           64  ] is an invalid data character in JavaScript compatibility mode
1499           65   different  names  for  subpatterns  of  the  same number are not           65  different names for subpatterns of the same number are
1500         allowed                 not allowed
1501           66  (*MARK) must have an argument           66  (*MARK) must have an argument
1502           67  this version of PCRE is not compiled with PCRE_UCP support           67  this version of PCRE is not compiled with PCRE_UCP support
1503    
# Line 1559  STUDYING A PATTERN Line 1559  STUDYING A PATTERN
1559         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
1560         which to start matching.         which to start matching.
1561    
1562           The two optimizations just described can be  disabled  by  setting  the
1563           PCRE_NO_START_OPTIMIZE    option    when    calling    pcre_exec()   or
1564           pcre_dfa_exec(). You might want to do this  if  your  pattern  contains
1565           callouts,  or  make  use of (*MARK), and you make use of these in cases
1566           where matching fails.  See  the  discussion  of  PCRE_NO_START_OPTIMIZE
1567           below.
1568    
1569    
1570  LOCALE SUPPORT  LOCALE SUPPORT
1571    
1572         PCRE handles caseless matching, and determines whether  characters  are         PCRE  handles  caseless matching, and determines whether characters are
1573         letters,  digits, or whatever, by reference to a set of tables, indexed         letters, digits, or whatever, by reference to a set of tables,  indexed
1574         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
1575         characters  with  codes  less than 128. By default, higher-valued codes         characters with codes less than 128. By  default,  higher-valued  codes
1576         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
1577         PCRE  is  built with Unicode character property support. Alternatively,         PCRE is built with Unicode character property  support.  Alternatively,
1578         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
1579         friends to use Unicode property support instead of built-in tables. The         friends to use Unicode property support instead of built-in tables. The
1580         use of locales with Unicode is discouraged. If you are handling charac-         use of locales with Unicode is discouraged. If you are handling charac-
1581         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-
1582         code, or use locales, but not try to mix the two.         code, or use locales, but not try to mix the two.
1583    
1584         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
1585         argument  of  pcre_compile()  is  NULL.  These  are sufficient for many         argument of pcre_compile() is  NULL.  These  are  sufficient  for  many
1586         applications.  Normally, the internal tables recognize only ASCII char-         applications.  Normally, the internal tables recognize only ASCII char-
1587         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-
1588         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,
1589         which may cause them to be different.         which may cause them to be different.
1590    
1591         The  internal tables can always be overridden by tables supplied by the         The internal tables can always be overridden by tables supplied by  the
1592         application that calls PCRE. These may be created in a different locale         application that calls PCRE. These may be created in a different locale
1593         from  the  default.  As more and more applications change to using Uni-         from the default. As more and more applications change  to  using  Uni-
1594         code, the need for this locale support is expected to die away.         code, the need for this locale support is expected to die away.
1595    
1596         External tables are built by calling  the  pcre_maketables()  function,         External  tables  are  built by calling the pcre_maketables() function,
1597         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
1598         passed to pcre_compile() or pcre_exec()  as  often  as  necessary.  For         passed  to  pcre_compile()  or  pcre_exec()  as often as necessary. For
1599         example,  to  build  and use tables that are appropriate for the French         example, to build and use tables that are appropriate  for  the  French
1600         locale (where accented characters with  values  greater  than  128  are         locale  (where  accented  characters  with  values greater than 128 are
1601         treated as letters), the following code could be used:         treated as letters), the following code could be used:
1602    
1603           setlocale(LC_CTYPE, "fr_FR");           setlocale(LC_CTYPE, "fr_FR");
1604           tables = pcre_maketables();           tables = pcre_maketables();
1605           re = pcre_compile(..., tables);           re = pcre_compile(..., tables);
1606    
1607         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;
1608         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".
1609    
1610         When pcre_maketables() runs, the tables are built  in  memory  that  is         When  pcre_maketables()  runs,  the  tables are built in memory that is
1611         obtained  via  pcre_malloc. It is the caller's responsibility to ensure         obtained via pcre_malloc. It is the caller's responsibility  to  ensure
1612         that the memory containing the tables remains available for as long  as         that  the memory containing the tables remains available for as long as
1613         it is needed.         it is needed.
1614    
1615         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
1616         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()
1617         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-
1618         tern, compilation, studying and matching all happen in the same locale,         tern, compilation, studying and matching all happen in the same locale,
1619         but different patterns can be compiled in different locales.         but different patterns can be compiled in different locales.
1620    
1621         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
1622         the internal tables) to pcre_exec(). Although  not  intended  for  this         the  internal  tables)  to  pcre_exec(). Although not intended for this
1623         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
1624         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
1625         run time is discussed below in the section on matching a pattern.         run time is discussed below in the section on matching a pattern.
1626    
# Line 1623  INFORMATION ABOUT A PATTERN Line 1630  INFORMATION ABOUT A PATTERN
1630         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,         int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
1631              int what, void *where);              int what, void *where);
1632    
1633         The  pcre_fullinfo() function returns information about a compiled pat-         The pcre_fullinfo() function returns information about a compiled  pat-
1634         tern. It replaces the obsolete pcre_info() function, which is neverthe-         tern. It replaces the obsolete pcre_info() function, which is neverthe-
1635         less retained for backwards compability (and is documented below).         less retained for backwards compability (and is documented below).
1636    
1637         The  first  argument  for  pcre_fullinfo() is a pointer to the compiled         The first argument for pcre_fullinfo() is a  pointer  to  the  compiled
1638         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
1639         the  pattern  was not studied. The third argument specifies which piece         the pattern was not studied. The third argument specifies  which  piece
1640         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
1641         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
1642         success, or one of the following negative numbers:         success, or one of the following negative numbers:
1643    
1644           PCRE_ERROR_NULL       the argument code was NULL           PCRE_ERROR_NULL       the argument code was NULL
# Line 1639  INFORMATION ABOUT A PATTERN Line 1646  INFORMATION ABOUT A PATTERN
1646           PCRE_ERROR_BADMAGIC   the "magic number" was not found           PCRE_ERROR_BADMAGIC   the "magic number" was not found
1647           PCRE_ERROR_BADOPTION  the value of what was invalid           PCRE_ERROR_BADOPTION  the value of what was invalid
1648    
1649         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
1650         an  simple check against passing an arbitrary memory pointer. Here is a         an simple check against passing an arbitrary memory pointer. Here is  a
1651         typical call of pcre_fullinfo(), to obtain the length of  the  compiled         typical  call  of pcre_fullinfo(), to obtain the length of the compiled
1652         pattern:         pattern:
1653    
1654           int rc;           int rc;
# Line 1652  INFORMATION ABOUT A PATTERN Line 1659  INFORMATION ABOUT A PATTERN
1659             PCRE_INFO_SIZE,   /* what is required */             PCRE_INFO_SIZE,   /* what is required */
1660             &length);         /* where to put the data */             &length);         /* where to put the data */
1661    
1662         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
1663         are as follows:         are as follows:
1664    
1665           PCRE_INFO_BACKREFMAX           PCRE_INFO_BACKREFMAX
1666    
1667         Return the number of the highest back reference  in  the  pattern.  The         Return  the  number  of  the highest back reference in the pattern. The
1668         fourth  argument  should  point to an int variable. Zero is returned if         fourth argument should point to an int variable. Zero  is  returned  if
1669         there are no back references.         there are no back references.
1670    
1671           PCRE_INFO_CAPTURECOUNT           PCRE_INFO_CAPTURECOUNT
1672    
1673         Return the number of capturing subpatterns in the pattern.  The  fourth         Return  the  number of capturing subpatterns in the pattern. The fourth
1674         argument should point to an int variable.         argument should point to an int variable.
1675    
1676           PCRE_INFO_DEFAULT_TABLES           PCRE_INFO_DEFAULT_TABLES
1677    
1678         Return  a pointer to the internal default character tables within PCRE.         Return a pointer to the internal default character tables within  PCRE.
1679         The fourth argument should point to an unsigned char *  variable.  This         The  fourth  argument should point to an unsigned char * variable. This
1680         information call is provided for internal use by the pcre_study() func-         information call is provided for internal use by the pcre_study() func-
1681         tion. External callers can cause PCRE to use  its  internal  tables  by         tion.  External  callers  can  cause PCRE to use its internal tables by
1682         passing a NULL table pointer.         passing a NULL table pointer.
1683    
1684           PCRE_INFO_FIRSTBYTE           PCRE_INFO_FIRSTBYTE
1685    
1686         Return  information  about  the first byte of any matched string, for a         Return information about the first byte of any matched  string,  for  a
1687         non-anchored pattern. The fourth argument should point to an int  vari-         non-anchored  pattern. The fourth argument should point to an int vari-
1688         able.  (This option used to be called PCRE_INFO_FIRSTCHAR; the old name         able. (This option used to be called PCRE_INFO_FIRSTCHAR; the old  name
1689         is still recognized for backwards compatibility.)         is still recognized for backwards compatibility.)
1690    
1691         If there is a fixed first byte, for example, from  a  pattern  such  as         If  there  is  a  fixed first byte, for example, from a pattern such as
1692         (cat|cow|coyote), its value is returned. Otherwise, if either         (cat|cow|coyote), its value is returned. Otherwise, if either
1693    
1694         (a)  the pattern was compiled with the PCRE_MULTILINE option, and every         (a) the pattern was compiled with the PCRE_MULTILINE option, and  every
1695         branch starts with "^", or         branch starts with "^", or
1696    
1697         (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
1698         set (if it were set, the pattern would be anchored),         set (if it were set, the pattern would be anchored),
1699    
1700         -1  is  returned, indicating that the pattern matches only at the start         -1 is returned, indicating that the pattern matches only at  the  start
1701         of a subject string or after any newline within the  string.  Otherwise         of  a  subject string or after any newline within the string. Otherwise
1702         -2 is returned. For anchored patterns, -2 is returned.         -2 is returned. For anchored patterns, -2 is returned.
1703    
1704           PCRE_INFO_FIRSTTABLE           PCRE_INFO_FIRSTTABLE
1705    
1706         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
1707         256-bit table indicating a fixed set of bytes for the first byte in any         256-bit table indicating a fixed set of bytes for the first byte in any
1708         matching  string, a pointer to the table is returned. Otherwise NULL is         matching string, a pointer to the table is returned. Otherwise NULL  is
1709         returned. The fourth argument should point to an unsigned char *  vari-         returned.  The fourth argument should point to an unsigned char * vari-
1710         able.         able.
1711    
1712           PCRE_INFO_HASCRORLF           PCRE_INFO_HASCRORLF
1713    
1714         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
1715         characters, otherwise 0. The fourth argument should  point  to  an  int         characters,  otherwise  0.  The  fourth argument should point to an int
1716         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
1717         \r or \n.         \r or \n.
1718    
1719           PCRE_INFO_JCHANGED           PCRE_INFO_JCHANGED
1720    
1721         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,
1722         otherwise  0. The fourth argument should point to an int variable. (?J)         otherwise 0. The fourth argument should point to an int variable.  (?J)
1723         and (?-J) set and unset the local PCRE_DUPNAMES option, respectively.         and (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
1724    
1725           PCRE_INFO_LASTLITERAL           PCRE_INFO_LASTLITERAL
1726    
1727         Return the value of the rightmost literal byte that must exist  in  any         Return  the  value of the rightmost literal byte that must exist in any
1728         matched  string,  other  than  at  its  start,  if such a byte has been         matched string, other than at its  start,  if  such  a  byte  has  been
1729         recorded. The fourth argument should point to an int variable. If there         recorded. The fourth argument should point to an int variable. If there
1730         is  no such byte, -1 is returned. For anchored patterns, a last literal         is no such byte, -1 is returned. For anchored patterns, a last  literal
1731         byte is recorded only if it follows something of variable  length.  For         byte  is  recorded only if it follows something of variable length. For
1732         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
1733         /^a\dz\d/ the returned value is -1.         /^a\dz\d/ the returned value is -1.
1734    
1735           PCRE_INFO_MINLENGTH           PCRE_INFO_MINLENGTH
1736    
1737         If the pattern was studied and a minimum length  for  matching  subject         If  the  pattern  was studied and a minimum length for matching subject
1738         strings  was  computed,  its  value is returned. Otherwise the returned         strings was computed, its value is  returned.  Otherwise  the  returned
1739         value is -1. The value is a number of characters, not bytes  (this  may         value  is  -1. The value is a number of characters, not bytes (this may
1740         be  relevant in UTF-8 mode). The fourth argument should point to an int         be relevant in UTF-8 mode). The fourth argument should point to an  int
1741         variable. A non-negative value is a lower bound to the  length  of  any         variable.  A  non-negative  value is a lower bound to the length of any
1742         matching  string.  There  may not be any strings of that length that do         matching string. There may not be any strings of that  length  that  do
1743         actually match, but every string that does match is at least that long.         actually match, but every string that does match is at least that long.
1744    
1745           PCRE_INFO_NAMECOUNT           PCRE_INFO_NAMECOUNT
1746           PCRE_INFO_NAMEENTRYSIZE           PCRE_INFO_NAMEENTRYSIZE
1747           PCRE_INFO_NAMETABLE           PCRE_INFO_NAMETABLE
1748    
1749         PCRE supports the use of named as well as numbered capturing  parenthe-         PCRE  supports the use of named as well as numbered capturing parenthe-
1750         ses.  The names are just an additional way of identifying the parenthe-         ses. The names are just an additional way of identifying the  parenthe-
1751         ses, which still acquire numbers. Several convenience functions such as         ses, which still acquire numbers. Several convenience functions such as
1752         pcre_get_named_substring()  are  provided  for extracting captured sub-         pcre_get_named_substring() are provided for  extracting  captured  sub-
1753         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
1754         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
1755         pointers in the output vector (described with pcre_exec() below). To do         pointers in the output vector (described with pcre_exec() below). To do
1756         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
1757         described by these three values.         described by these three values.
1758    
1759         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
1760         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size         gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size
1761         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
1762         depends  on the length of the longest name. PCRE_INFO_NAMETABLE returns         depends on the length of the longest name. PCRE_INFO_NAMETABLE  returns
1763         a pointer to the first entry of the table  (a  pointer  to  char).  The         a  pointer  to  the  first  entry of the table (a pointer to char). The
1764         first two bytes of each entry are the number of the capturing parenthe-         first two bytes of each entry are the number of the capturing parenthe-
1765         sis, most significant byte first. The rest of the entry is  the  corre-         sis,  most  significant byte first. The rest of the entry is the corre-
1766         sponding name, zero terminated.         sponding name, zero terminated.
1767    
1768         The  names are in alphabetical order. Duplicate names may appear if (?|         The names are in alphabetical order. Duplicate names may appear if  (?|
1769         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
1770         the  section  on  duplicate subpattern numbers in the pcrepattern page.         the section on duplicate subpattern numbers in  the  pcrepattern  page.
1771         Duplicate names for subpatterns with different  numbers  are  permitted         Duplicate  names  for  subpatterns with different numbers are permitted
1772         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
1773         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-
1774         tern.  In  the  absence  of (?| this is the order of increasing number;         tern. In the absence of (?| this is the  order  of  increasing  number;
1775         when (?| is used this is not necessarily the case because later subpat-         when (?| is used this is not necessarily the case because later subpat-
1776         terns may have lower numbers.         terns may have lower numbers.
1777    
1778         As  a  simple  example of the name/number table, consider the following         As a simple example of the name/number table,  consider  the  following
1779         pattern (assume PCRE_EXTENDED is set, so white space -  including  new-         pattern  (assume  PCRE_EXTENDED is set, so white space - including new-
1780         lines - is ignored):         lines - is ignored):
1781    
1782           (?<date> (?<year>(\d\d)?\d\d) -           (?<date> (?<year>(\d\d)?\d\d) -
1783           (?<month>\d\d) - (?<day>\d\d) )           (?<month>\d\d) - (?<day>\d\d) )
1784    
1785         There  are  four  named subpatterns, so the table has four entries, and         There are four named subpatterns, so the table has  four  entries,  and
1786         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,
1787         with non-printing bytes shows in hexadecimal, and undefined bytes shown         with non-printing bytes shows in hexadecimal, and undefined bytes shown
1788         as ??:         as ??:
1789    
# Line 1785  INFORMATION ABOUT A PATTERN Line 1792  INFORMATION ABOUT A PATTERN
1792           00 04 m  o  n  t  h  00           00 04 m  o  n  t  h  00
1793           00 02 y  e  a  r  00 ??           00 02 y  e  a  r  00 ??
1794    
1795         When writing code to extract data  from  named  subpatterns  using  the         When  writing  code  to  extract  data from named subpatterns using the
1796         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
1797         to be different for each compiled pattern.         to be different for each compiled pattern.
1798    
1799           PCRE_INFO_OKPARTIAL           PCRE_INFO_OKPARTIAL
1800    
1801         Return 1  if  the  pattern  can  be  used  for  partial  matching  with         Return  1  if  the  pattern  can  be  used  for  partial  matching with
1802         pcre_exec(),  otherwise  0.  The fourth argument should point to an int         pcre_exec(), otherwise 0. The fourth argument should point  to  an  int
1803         variable. From  release  8.00,  this  always  returns  1,  because  the         variable.  From  release  8.00,  this  always  returns  1,  because the
1804         restrictions  that  previously  applied  to  partial matching have been         restrictions that previously applied  to  partial  matching  have  been
1805         lifted. The pcrepartial documentation gives details of  partial  match-         lifted.  The  pcrepartial documentation gives details of partial match-
1806         ing.         ing.
1807    
1808           PCRE_INFO_OPTIONS           PCRE_INFO_OPTIONS
1809    
1810         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
1811         fourth argument should point to an unsigned long  int  variable.  These         fourth  argument  should  point to an unsigned long int variable. These
1812         option bits are those specified in the call to pcre_compile(), modified         option bits are those specified in the call to pcre_compile(), modified
1813         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
1814         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
1815         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
1816         the  PCRE_EXTENDED option, the result is PCRE_CASELESS, PCRE_MULTILINE,         the PCRE_EXTENDED option, the result is PCRE_CASELESS,  PCRE_MULTILINE,
1817         and PCRE_EXTENDED.         and PCRE_EXTENDED.
1818    
1819         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
1820         alternatives begin with one of the following:         alternatives begin with one of the following:
1821    
1822           ^     unless PCRE_MULTILINE is set           ^     unless PCRE_MULTILINE is set
# Line 1823  INFORMATION ABOUT A PATTERN Line 1830  INFORMATION ABOUT A PATTERN
1830    
1831           PCRE_INFO_SIZE           PCRE_INFO_SIZE
1832    
1833         Return the size of the compiled pattern, that is, the  value  that  was         Return  the  size  of the compiled pattern, that is, the value that was
1834         passed as the argument to pcre_malloc() when PCRE was getting memory in         passed as the argument to pcre_malloc() when PCRE was getting memory in
1835         which to place the compiled data. The fourth argument should point to a         which to place the compiled data. The fourth argument should point to a
1836         size_t variable.         size_t variable.
# Line 1831  INFORMATION ABOUT A PATTERN Line 1838  INFORMATION ABOUT A PATTERN
1838           PCRE_INFO_STUDYSIZE           PCRE_INFO_STUDYSIZE
1839    
1840         Return the size of the data block pointed to by the study_data field in         Return the size of the data block pointed to by the study_data field in
1841         a pcre_extra block. That is,  it  is  the  value  that  was  passed  to         a  pcre_extra  block.  That  is,  it  is  the  value that was passed to
1842         pcre_malloc() when PCRE was getting memory into which to place the data         pcre_malloc() when PCRE was getting memory into which to place the data
1843         created by pcre_study(). If pcre_extra is NULL, or there  is  no  study         created  by  pcre_study().  If pcre_extra is NULL, or there is no study
1844         data,  zero  is  returned. The fourth argument should point to a size_t         data, zero is returned. The fourth argument should point  to  a  size_t
1845         variable.         variable.
1846    
1847    
# Line 1842  OBSOLETE INFO FUNCTION Line 1849  OBSOLETE INFO FUNCTION
1849    
1850         int pcre_info(const pcre *code, int *optptr, int *firstcharptr);         int pcre_info(const pcre *code, int *optptr, int *firstcharptr);
1851    
1852         The pcre_info() function is now obsolete because its interface  is  too         The  pcre_info()  function is now obsolete because its interface is too
1853         restrictive  to return all the available data about a compiled pattern.         restrictive to return all the available data about a compiled  pattern.
1854         New  programs  should  use  pcre_fullinfo()  instead.  The   yield   of         New   programs   should  use  pcre_fullinfo()  instead.  The  yield  of
1855         pcre_info()  is the number of capturing subpatterns, or one of the fol-         pcre_info() is the number of capturing subpatterns, or one of the  fol-
1856         lowing negative numbers:         lowing negative numbers:
1857    
1858           PCRE_ERROR_NULL       the argument code was NULL           PCRE_ERROR_NULL       the argument code was NULL
1859           PCRE_ERROR_BADMAGIC   the "magic number" was not found           PCRE_ERROR_BADMAGIC   the "magic number" was not found
1860    
1861         If the optptr argument is not NULL, a copy of the  options  with  which         If  the  optptr  argument is not NULL, a copy of the options with which
1862         the  pattern  was  compiled  is placed in the integer it points to (see         the pattern was compiled is placed in the integer  it  points  to  (see
1863         PCRE_INFO_OPTIONS above).         PCRE_INFO_OPTIONS above).
1864    
1865         If the pattern is not anchored and the  firstcharptr  argument  is  not         If  the  pattern  is  not anchored and the firstcharptr argument is not
1866         NULL,  it is used to pass back information about the first character of         NULL, it is used to pass back information about the first character  of
1867         any matched string (see PCRE_INFO_FIRSTBYTE above).         any matched string (see PCRE_INFO_FIRSTBYTE above).
1868    
1869    
# Line 1864  REFERENCE COUNTS Line 1871  REFERENCE COUNTS
1871    
1872         int pcre_refcount(pcre *code, int adjust);         int pcre_refcount(pcre *code, int adjust);
1873    
1874         The pcre_refcount() function is used to maintain a reference  count  in         The  pcre_refcount()  function is used to maintain a reference count in
1875         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
1876         benefit of applications that  operate  in  an  object-oriented  manner,         benefit  of  applications  that  operate  in an object-oriented manner,
1877         where different parts of the application may be using the same compiled         where different parts of the application may be using the same compiled
1878         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.
1879    
1880         When a pattern is compiled, the reference count field is initialized to         When a pattern is compiled, the reference count field is initialized to
1881         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
1882         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
1883         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
1884         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
1885         is outside these limits, it is forced to the appropriate limit value.         is outside these limits, it is forced to the appropriate limit value.
1886    
1887         Except  when it is zero, the reference count is not correctly preserved         Except when it is zero, the reference count is not correctly  preserved
1888         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
1889         whose byte-order is different. (This seems a highly unlikely scenario.)         whose byte-order is different. (This seems a highly unlikely scenario.)
1890    
1891    
# Line 1888  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 1895  MATCHING A PATTERN: THE TRADITIONAL FUNC
1895              const char *subject, int length, int startoffset,              const char *subject, int length, int startoffset,
1896              int options, int *ovector, int ovecsize);              int options, int *ovector, int ovecsize);
1897    
1898         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
1899         compiled pattern, which is passed in the code argument. If the  pattern         compiled  pattern, which is passed in the code argument. If the pattern
1900         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
1901         argument. This function is the main matching facility of  the  library,         argument.  This  function is the main matching facility of the library,
1902         and it operates in a Perl-like manner. For specialist use there is also         and it operates in a Perl-like manner. For specialist use there is also
1903         an alternative matching function, which is described below in the  sec-         an  alternative matching function, which is described below in the sec-
1904         tion about the pcre_dfa_exec() function.         tion about the pcre_dfa_exec() function.
1905    
1906         In  most applications, the pattern will have been compiled (and option-         In most applications, the pattern will have been compiled (and  option-
1907         ally studied) in the same process that calls pcre_exec().  However,  it         ally  studied)  in the same process that calls pcre_exec(). However, it
1908         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
1909         later in different processes, possibly even on different hosts.  For  a         later  in  different processes, possibly even on different hosts. For a
1910         discussion about this, see the pcreprecompile documentation.         discussion about this, see the pcreprecompile documentation.
1911    
1912         Here is an example of a simple call to pcre_exec():         Here is an example of a simple call to pcre_exec():
# Line 1918  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 1925  MATCHING A PATTERN: THE TRADITIONAL FUNC
1925    
1926     Extra data for pcre_exec()     Extra data for pcre_exec()
1927    
1928         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
1929         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
1930         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-
1931         tional information in it. The pcre_extra block contains  the  following         tional  information  in it. The pcre_extra block contains the following
1932         fields (not necessarily in this order):         fields (not necessarily in this order):
1933    
1934           unsigned long int flags;           unsigned long int flags;
# Line 1932  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 1939  MATCHING A PATTERN: THE TRADITIONAL FUNC
1939           const unsigned char *tables;           const unsigned char *tables;
1940           unsigned char **mark;           unsigned char **mark;
1941    
1942         The  flags  field  is a bitmap that specifies which of the other fields         The flags field is a bitmap that specifies which of  the  other  fields
1943         are set. The flag bits are:         are set. The flag bits are:
1944    
1945           PCRE_EXTRA_STUDY_DATA           PCRE_EXTRA_STUDY_DATA
# Line 1942  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 1949  MATCHING A PATTERN: THE TRADITIONAL FUNC
1949           PCRE_EXTRA_TABLES           PCRE_EXTRA_TABLES
1950           PCRE_EXTRA_MARK           PCRE_EXTRA_MARK
1951    
1952         Other flag bits should be set to zero. The study_data field is  set  in         Other  flag  bits should be set to zero. The study_data field is set in
1953         the  pcre_extra  block  that is returned by pcre_study(), together with         the pcre_extra block that is returned by  pcre_study(),  together  with
1954         the appropriate flag bit. You should not set this yourself, but you may         the appropriate flag bit. You should not set this yourself, but you may
1955         add  to  the  block by setting the other fields and their corresponding         add to the block by setting the other fields  and  their  corresponding
1956         flag bits.         flag bits.
1957    
1958         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
1959         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
1960         match, but which have a very large number  of  possibilities  in  their         match,  but  which  have  a very large number of possibilities in their
1961         search  trees. The classic example is a pattern that uses nested unlim-         search trees. The classic example is a pattern that uses nested  unlim-
1962         ited repeats.         ited repeats.
1963    
1964         Internally, PCRE uses a function called match() which it calls  repeat-         Internally,  PCRE uses a function called match() which it calls repeat-
1965         edly  (sometimes  recursively). The limit set by match_limit is imposed         edly (sometimes recursively). The limit set by match_limit  is  imposed
1966         on the number of times this function is called during  a  match,  which         on  the  number  of times this function is called during a match, which
1967         has  the  effect  of  limiting the amount of backtracking that can take         has the effect of limiting the amount of  backtracking  that  can  take
1968         place. For patterns that are not anchored, the count restarts from zero         place. For patterns that are not anchored, the count restarts from zero
1969         for each position in the subject string.         for each position in the subject string.
1970    
1971         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
1972         default default is 10 million, which handles all but the  most  extreme         default  default  is 10 million, which handles all but the most extreme
1973         cases.  You  can  override  the  default by suppling pcre_exec() with a         cases. You can override the default  by  suppling  pcre_exec()  with  a
1974         pcre_extra    block    in    which    match_limit    is    set,     and         pcre_extra     block    in    which    match_limit    is    set,    and
1975         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
1976         exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.         exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
1977    
1978         The match_limit_recursion field is similar to match_limit, but  instead         The  match_limit_recursion field is similar to match_limit, but instead
1979         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
1980         the depth of recursion. The recursion depth is a  smaller  number  than         the  depth  of  recursion. The recursion depth is a smaller number than
1981         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-
1982         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.
1983    
1984         Limiting the recursion depth limits the amount of  stack  that  can  be         Limiting  the  recursion  depth  limits the amount of stack that can be
1985         used, or, when PCRE has been compiled to use memory on the heap instead         used, or, when PCRE has been compiled to use memory on the heap instead
1986         of the stack, the amount of heap memory that can be used.         of the stack, the amount of heap memory that can be used.
1987    
1988         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
1989         built;  the  default  default  is  the  same  value  as the default for         built; the default default  is  the  same  value  as  the  default  for
1990         match_limit. You can override the default by suppling pcre_exec()  with         match_limit.  You can override the default by suppling pcre_exec() with
1991         a   pcre_extra   block  in  which  match_limit_recursion  is  set,  and         a  pcre_extra  block  in  which  match_limit_recursion  is   set,   and
1992         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
1993         limit is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.         limit is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.
1994    
1995         The  callout_data  field is used in conjunction with the "callout" fea-         The callout_data field is used in conjunction with the  "callout"  fea-
1996         ture, and is described in the pcrecallout documentation.         ture, and is described in the pcrecallout documentation.
1997    
1998         The tables field  is  used  to  pass  a  character  tables  pointer  to         The  tables  field  is  used  to  pass  a  character  tables pointer to
1999         pcre_exec();  this overrides the value that is stored with the compiled         pcre_exec(); this overrides the value that is stored with the  compiled
2000         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
2001         custom  tables  were  supplied to pcre_compile() via its tableptr argu-         custom tables were supplied to pcre_compile() via  its  tableptr  argu-
2002         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
2003         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-
2004         using patterns that have been saved after compiling  with  an  external         using  patterns  that  have been saved after compiling with an external
2005         set  of  tables,  because  the  external tables might be at a different         set of tables, because the external tables  might  be  at  a  different
2006         address when pcre_exec() is called. See the  pcreprecompile  documenta-         address  when  pcre_exec() is called. See the pcreprecompile documenta-
2007         tion for a discussion of saving compiled patterns for later use.         tion for a discussion of saving compiled patterns for later use.
2008    
2009         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
2010         set to point to a char * variable. If the pattern  contains  any  back-         set  to  point  to a char * variable. If the pattern contains any back-
2011         tracking  control verbs such as (*MARK:NAME), and the execution ends up         tracking control verbs such as (*MARK:NAME), and the execution ends  up
2012         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-
2013         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
2014         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
2015         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.
2016         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
2017         field  set  to NULL. For details of the backtracking control verbs, see         field set to NULL. For details of the backtracking control  verbs,  see
2018         the section entitled "Backtracking control" in the pcrepattern documen-         the section entitled "Backtracking control" in the pcrepattern documen-
2019         tation.         tation.
2020    
2021     Option bits for pcre_exec()     Option bits for pcre_exec()
2022    
2023         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.
2024         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,
2025         PCRE_NOTBOL,    PCRE_NOTEOL,    PCRE_NOTEMPTY,   PCRE_NOTEMPTY_ATSTART,         PCRE_NOTBOL,   PCRE_NOTEOL,    PCRE_NOTEMPTY,    PCRE_NOTEMPTY_ATSTART,
2026         PCRE_NO_START_OPTIMIZE,  PCRE_NO_UTF8_CHECK,   PCRE_PARTIAL_SOFT,   and         PCRE_NO_START_OPTIMIZE,   PCRE_NO_UTF8_CHECK,   PCRE_PARTIAL_SOFT,  and
2027         PCRE_PARTIAL_HARD.         PCRE_PARTIAL_HARD.
2028    
2029           PCRE_ANCHORED           PCRE_ANCHORED
2030    
2031         The  PCRE_ANCHORED  option  limits pcre_exec() to matching at the first         The PCRE_ANCHORED option limits pcre_exec() to matching  at  the  first
2032         matching position. If a pattern was  compiled  with  PCRE_ANCHORED,  or         matching  position.  If  a  pattern was compiled with PCRE_ANCHORED, or
2033         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
2034         unachored at matching time.         unachored at matching time.
2035    
2036           PCRE_BSR_ANYCRLF           PCRE_BSR_ANYCRLF
2037           PCRE_BSR_UNICODE           PCRE_BSR_UNICODE
2038    
2039         These options (which are mutually exclusive) control what the \R escape         These options (which are mutually exclusive) control what the \R escape
2040         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,
2041         or to match any Unicode newline sequence. These  options  override  the         or  to  match  any Unicode newline sequence. These options override the
2042         choice that was made or defaulted when the pattern was compiled.         choice that was made or defaulted when the pattern was compiled.
2043    
2044           PCRE_NEWLINE_CR           PCRE_NEWLINE_CR
# Line 2040  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2047  MATCHING A PATTERN: THE TRADITIONAL FUNC
2047           PCRE_NEWLINE_ANYCRLF           PCRE_NEWLINE_ANYCRLF
2048           PCRE_NEWLINE_ANY           PCRE_NEWLINE_ANY
2049    
2050         These  options  override  the  newline  definition  that  was chosen or         These options override  the  newline  definition  that  was  chosen  or
2051         defaulted when the pattern was compiled. For details, see the  descrip-         defaulted  when the pattern was compiled. For details, see the descrip-
2052         tion  of  pcre_compile()  above.  During  matching,  the newline choice         tion of pcre_compile()  above.  During  matching,  the  newline  choice
2053         affects the behaviour of the dot, circumflex,  and  dollar  metacharac-         affects  the  behaviour  of the dot, circumflex, and dollar metacharac-
2054         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
2055         match failure for an unanchored pattern.         match failure for an unanchored pattern.
2056    
2057         When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF,  or  PCRE_NEWLINE_ANY  is         When  PCRE_NEWLINE_CRLF,  PCRE_NEWLINE_ANYCRLF,  or PCRE_NEWLINE_ANY is
2058         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-
2059         rent position is at a  CRLF  sequence,  and  the  pattern  contains  no         rent  position  is  at  a  CRLF  sequence,  and the pattern contains no
2060         explicit  matches  for  CR  or  LF  characters,  the  match position is         explicit matches for  CR  or  LF  characters,  the  match  position  is
2061         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
2062         CRLF.         CRLF.
2063    
2064         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
2065         expected. For example, if the  pattern  is  .+A  (and  the  PCRE_DOTALL         expected.  For  example,  if  the  pattern  is .+A (and the PCRE_DOTALL
2066         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
2067         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.
2068         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-
2069         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-
2070         acter after the first failure.         acter after the first failure.
2071    
2072         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
2073         those characters, or one of the \r or  \n  escape  sequences.  Implicit         those  characters,  or  one  of the \r or \n escape sequences. Implicit
2074         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
2075         LF in the characters that it matches).         LF in the characters that it matches).
2076    
2077         Notwithstanding the above, anomalous effects may still occur when  CRLF         Notwithstanding  the above, anomalous effects may still occur when CRLF
2078         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
2079         pattern.         pattern.
2080    
2081           PCRE_NOTBOL           PCRE_NOTBOL
2082    
2083         This option specifies that first character of the subject string is not         This option specifies that first character of the subject string is not
2084         the  beginning  of  a  line, so the circumflex metacharacter should not         the beginning of a line, so the  circumflex  metacharacter  should  not
2085         match before it. Setting this without PCRE_MULTILINE (at compile  time)         match  before it. Setting this without PCRE_MULTILINE (at compile time)
2086         causes  circumflex  never to match. This option affects only the behav-         causes circumflex never to match. This option affects only  the  behav-
2087         iour of the circumflex metacharacter. It does not affect \A.         iour of the circumflex metacharacter. It does not affect \A.
2088    
2089           PCRE_NOTEOL           PCRE_NOTEOL
2090    
2091         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
2092         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
2093         in multiline mode) a newline immediately before it. Setting this  with-         in  multiline mode) a newline immediately before it. Setting this with-
2094         out PCRE_MULTILINE (at compile time) causes dollar never to match. This         out PCRE_MULTILINE (at compile time) causes dollar never to match. This
2095         option affects only the behaviour of the dollar metacharacter. It  does         option  affects only the behaviour of the dollar metacharacter. It does
2096         not affect \Z or \z.         not affect \Z or \z.
2097    
2098           PCRE_NOTEMPTY           PCRE_NOTEMPTY
2099    
2100         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
2101         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
2102         the  alternatives  match  the empty string, the entire match fails. For         the alternatives match the empty string, the entire  match  fails.  For
2103         example, if the pattern         example, if the pattern
2104    
2105           a?b?           a?b?
2106    
2107         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
2108         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
2109         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-
2110         rences of "a" or "b".         rences of "a" or "b".
2111    
2112           PCRE_NOTEMPTY_ATSTART           PCRE_NOTEMPTY_ATSTART
2113    
2114         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
2115         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
2116         anchored, such a match can occur only if the pattern contains \K.         anchored, such a match can occur only if the pattern contains \K.
2117    
2118         Perl     has    no    direct    equivalent    of    PCRE_NOTEMPTY    or         Perl    has    no    direct    equivalent    of    PCRE_NOTEMPTY     or
2119         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
2120         match  of  the empty string within its split() function, and when using         match of the empty string within its split() function, and  when  using
2121         the /g modifier. It is  possible  to  emulate  Perl's  behaviour  after         the  /g  modifier.  It  is  possible  to emulate Perl's behaviour after
2122         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-
2123         set with PCRE_NOTEMPTY_ATSTART and  PCRE_ANCHORED,  and  then  if  that         set  with  PCRE_NOTEMPTY_ATSTART  and  PCRE_ANCHORED,  and then if that
2124         fails, by advancing the starting offset (see below) and trying an ordi-         fails, by advancing the starting offset (see below) and trying an ordi-
2125         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
2126         in the pcredemo sample program.         in the pcredemo sample program.
2127    
2128           PCRE_NO_START_OPTIMIZE           PCRE_NO_START_OPTIMIZE
2129    
2130         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
2131         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
2132         known that an unanchored match must start with a specific character, it         known that an unanchored match must start with a specific character, it
2133         searches the subject for that character, and fails  immediately  if  it         searches  the  subject  for that character, and fails immediately if it
2134         cannot  find  it,  without actually running the main matching function.         cannot find it, without actually running the  main  matching  function.
2135         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-
2136         tern  is  not  considered until after a suitable starting point for the         tern is not considered until after a suitable starting  point  for  the
2137         match has been found. When callouts are in use, these "start-up"  opti-         match  has been found. When callouts or (*MARK) items are in use, these
2138         mizations can cause them to be skipped if the pattern is never actually         "start-up" optimizations can cause them to be skipped if the pattern is
2139         used. The PCRE_NO_START_OPTIMIZE option disables the start-up optimiza-         never  actually  used.  The start-up optimizations are in effect a pre-
2140         tions, causing performance to suffer, but ensuring that the callouts do         scan of the subject that takes place before the pattern is run.
2141         occur, and that items such as (*COMMIT) are considered at every  possi-  
2142         ble starting position in the subject string.         The PCRE_NO_START_OPTIMIZE option disables the start-up  optimizations,
2143           possibly  causing  performance  to  suffer,  but ensuring that in cases
2144           where the result is "no match", the callouts do occur, and  that  items
2145           such as (*COMMIT) and (*MARK) are considered at every possible starting
2146           position in the subject  string.   Setting  PCRE_NO_START_OPTIMIZE  can
2147           change the outcome of a matching operation.  Consider the pattern
2148    
2149             (*COMMIT)ABC
2150    
2151           When  this  is  compiled, PCRE records the fact that a match must start
2152           with the character "A". Suppose the subject  string  is  "DEFABC".  The
2153           start-up  optimization  scans along the subject, finds "A" and runs the
2154           first match attempt from there. The (*COMMIT) item means that the  pat-
2155           tern  must  match the current starting position, which in this case, it
2156           does. However, if the same match  is  run  with  PCRE_NO_START_OPTIMIZE
2157           set,  the  initial  scan  along the subject string does not happen. The
2158           first match attempt is run starting  from  "D"  and  when  this  fails,
2159           (*COMMIT)  prevents  any  further  matches  being tried, so the overall
2160           result is "no match". If the pattern is studied,  more  start-up  opti-
2161           mizations  may  be  used. For example, a minimum length for the subject
2162           may be recorded. Consider the pattern
2163    
2164             (*MARK:A)(X|Y)
2165    
2166           The minimum length for a match is one  character.  If  the  subject  is
2167           "ABC",  there  will  be  attempts  to  match "ABC", "BC", "C", and then
2168           finally an empty string.  If the pattern is studied, the final  attempt
2169           does  not take place, because PCRE knows that the subject is too short,
2170           and so the (*MARK) is never encountered.  In this  case,  studying  the
2171           pattern  does  not  affect the overall match result, which is still "no
2172           match", but it does affect the auxiliary information that is returned.
2173    
2174           PCRE_NO_UTF8_CHECK           PCRE_NO_UTF8_CHECK
2175    
2176         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
2177         UTF-8 string is automatically checked when pcre_exec() is  subsequently         UTF-8  string is automatically checked when pcre_exec() is subsequently
2178         called.   The  value  of  startoffset is also checked to ensure that it         called.  The value of startoffset is also checked  to  ensure  that  it
2179         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
2180         the  validity  of  UTF-8 strings in the section on UTF-8 support in the         the validity of UTF-8 strings in the section on UTF-8  support  in  the
2181         main pcre page. If  an  invalid  UTF-8  sequence  of  bytes  is  found,         main  pcre  page.  If  an  invalid  UTF-8  sequence  of bytes is found,
2182         pcre_exec()  returns  the error PCRE_ERROR_BADUTF8. If startoffset con-         pcre_exec() returns the error PCRE_ERROR_BADUTF8. If  startoffset  con-
2183         tains an invalid value, PCRE_ERROR_BADUTF8_OFFSET is returned.         tains an invalid value, PCRE_ERROR_BADUTF8_OFFSET is returned.
2184    
2185         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
2186         these    checks    for   performance   reasons,   you   can   set   the         these   checks   for   performance   reasons,   you   can    set    the
2187         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
2188         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
2189         making repeated calls to find all  the  matches  in  a  single  subject         making  repeated  calls  to  find  all  the matches in a single subject
2190         string.  However,  you  should  be  sure  that the value of startoffset         string. However, you should be  sure  that  the  value  of  startoffset
2191         points to the start of a UTF-8 character.  When  PCRE_NO_UTF8_CHECK  is         points  to  the  start of a UTF-8 character. When PCRE_NO_UTF8_CHECK is
2192         set,  the  effect of passing an invalid UTF-8 string as a subject, or a         set, the effect of passing an invalid UTF-8 string as a subject,  or  a
2193         value of startoffset that does not point to the start of a UTF-8  char-         value  of startoffset that does not point to the start of a UTF-8 char-
2194         acter, is undefined. Your program may crash.         acter, is undefined. Your program may crash.
2195    
2196           PCRE_PARTIAL_HARD           PCRE_PARTIAL_HARD
2197           PCRE_PARTIAL_SOFT           PCRE_PARTIAL_SOFT
2198    
2199         These  options turn on the partial matching feature. For backwards com-         These options turn on the partial matching feature. For backwards  com-
2200         patibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A  partial         patibility,  PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial
2201         match  occurs if the end of the subject string is reached successfully,         match occurs if the end of the subject string is reached  successfully,
2202         but there are not enough subject characters to complete the  match.  If         but  there  are not enough subject characters to complete the match. If
2203         this  happens  when  PCRE_PARTIAL_HARD  is set, pcre_exec() immediately         this happens when PCRE_PARTIAL_HARD  is  set,  pcre_exec()  immediately
2204         returns PCRE_ERROR_PARTIAL. Otherwise,  if  PCRE_PARTIAL_SOFT  is  set,         returns  PCRE_ERROR_PARTIAL.  Otherwise,  if  PCRE_PARTIAL_SOFT is set,
2205         matching  continues by testing any other alternatives. Only if they all         matching continues by testing any other alternatives. Only if they  all
2206         fail is PCRE_ERROR_PARTIAL returned  (instead  of  PCRE_ERROR_NOMATCH).         fail  is  PCRE_ERROR_PARTIAL  returned (instead of PCRE_ERROR_NOMATCH).
2207         The portion of the string that was inspected when the partial match was         The portion of the string that was inspected when the partial match was
2208         found is set as the first matching string. There  is  a  more  detailed         found  is  set  as  the first matching string. There is a more detailed
2209         discussion in the pcrepartial documentation.         discussion in the pcrepartial documentation.
2210    
2211     The string to be matched by pcre_exec()     The string to be matched by pcre_exec()
2212    
2213         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
2214         length (in bytes) in length, and a starting byte offset in startoffset.         length (in bytes) in length, and a starting byte offset in startoffset.
2215         In UTF-8 mode, the byte offset must point to the start of a UTF-8 char-         In UTF-8 mode, the byte offset must point to the start of a UTF-8 char-
2216         acter. Unlike the pattern string, the subject may contain  binary  zero         acter.  Unlike  the pattern string, the subject may contain binary zero
2217         bytes.  When the starting offset is zero, the search for a match starts         bytes. When the starting offset is zero, the search for a match  starts
2218         at the beginning of the subject, and this is by  far  the  most  common         at  the  beginning  of  the subject, and this is by far the most common
2219         case.         case.
2220    
2221         A  non-zero  starting offset is useful when searching for another match         A non-zero starting offset is useful when searching for  another  match
2222         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-
2223         cess.   Setting  startoffset differs from just passing over a shortened         cess.  Setting startoffset differs from just passing over  a  shortened
2224         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
2225         with any kind of lookbehind. For example, consider the pattern         with any kind of lookbehind. For example, consider the pattern
2226    
2227           \Biss\B           \Biss\B
2228    
2229         which  finds  occurrences  of "iss" in the middle of words. (\B matches         which finds occurrences of "iss" in the middle of  words.  (\B  matches
2230         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.)
2231         When  applied  to the string "Mississipi" the first call to pcre_exec()         When applied to the string "Mississipi" the first call  to  pcre_exec()
2232         finds the first occurrence. If pcre_exec() is called  again  with  just         finds  the  first  occurrence. If pcre_exec() is called again with just
2233         the  remainder  of  the  subject,  namely  "issipi", it does not match,         the remainder of the subject,  namely  "issipi",  it  does  not  match,
2234         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
2235         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
2236         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-
2237         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
2238         discover that it is preceded by a letter.         discover that it is preceded by a letter.
2239    
2240         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,
2241         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
2242         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
2243         subject.         subject.
2244    
2245     How pcre_exec() returns captured substrings     How pcre_exec() returns captured substrings
2246    
2247         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
2248         addition, further substrings from the subject  may  be  picked  out  by         addition,  further  substrings  from  the  subject may be picked out by
2249         parts  of  the  pattern.  Following the usage in Jeffrey Friedl's book,         parts of the pattern. Following the usage  in  Jeffrey  Friedl's  book,
2250         this is called "capturing" in what follows, and the  phrase  "capturing         this  is  called "capturing" in what follows, and the phrase "capturing
2251         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-
2252         string. PCRE supports several other kinds of  parenthesized  subpattern         string.  PCRE  supports several other kinds of parenthesized subpattern
2253         that do not cause substrings to be captured.         that do not cause substrings to be captured.
2254    
2255         Captured substrings are returned to the caller via a vector of integers         Captured substrings are returned to the caller via a vector of integers
2256         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-
2257         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:
2258         this argument is NOT the size of ovector in bytes.         this argument is NOT the size of ovector in bytes.
2259    
2260         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-
2261         strings,  each  substring using a pair of integers. The remaining third         strings, each substring using a pair of integers. The  remaining  third
2262         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-
2263         turing  subpatterns, and is not available for passing back information.         turing subpatterns, and is not available for passing back  information.
2264         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
2265         it is not, it is rounded down.         it is not, it is rounded down.
2266    
2267         When  a  match  is successful, information about captured substrings is         When a match is successful, information about  captured  substrings  is
2268         returned in pairs of integers, starting at the  beginning  of  ovector,         returned  in  pairs  of integers, starting at the beginning of ovector,
2269         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
2270         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
2271         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
2272         character after the end of a substring. Note: these values  are  always         character  after  the end of a substring. Note: these values are always
2273         byte offsets, even in UTF-8 mode. They are not character counts.         byte offsets, even in UTF-8 mode. They are not character counts.
2274    
2275         The  first  pair  of  integers, ovector[0] and ovector[1], identify the         The first pair of integers, ovector[0]  and  ovector[1],  identify  the
2276         portion of the subject string matched by the entire pattern.  The  next         portion  of  the subject string matched by the entire pattern. The next
2277         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
2278         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
2279         has  been  set.  For example, if two substrings have been captured, the         has been set.  For example, if two substrings have been  captured,  the
2280         returned value is 3. If there are no capturing subpatterns, the  return         returned  value is 3. If there are no capturing subpatterns, the return
2281         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
2282         of offsets has been set.         of offsets has been set.
2283    
2284         If a capturing subpattern is matched repeatedly, it is the last portion         If a capturing subpattern is matched repeatedly, it is the last portion
2285         of the string that it matched that is returned.         of the string that it matched that is returned.
2286    
2287         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,
2288         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
2289         function  returns  a value of zero. If the substring offsets are not of         function returns a value of zero. If the substring offsets are  not  of
2290         interest, pcre_exec() may be called with ovector  passed  as  NULL  and         interest,  pcre_exec()  may  be  called with ovector passed as NULL and
2291         ovecsize  as zero. However, if the pattern contains back references and         ovecsize as zero. However, if the pattern contains back references  and
2292         the ovector is not big enough to remember the related substrings,  PCRE         the  ovector is not big enough to remember the related substrings, PCRE
2293         has  to  get additional memory for use during matching. Thus it is usu-         has to get additional memory for use during matching. Thus it  is  usu-
2294         ally advisable to supply an ovector.         ally advisable to supply an ovector.
2295    
2296         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
2297         subpatterns  there  are  in  a  compiled pattern. The smallest size for         subpatterns there are in a compiled  pattern.  The  smallest  size  for
2298         ovector that will allow for n captured substrings, in addition  to  the         ovector  that  will allow for n captured substrings, in addition to the
2299         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.
2300    
2301         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
2302         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,
2303         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
2304         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
2305         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-
2306         sponding to unused subpatterns are set to -1.         sponding to unused subpatterns are set to -1.
2307    
2308         Offset values that correspond to unused subpatterns at the end  of  the         Offset  values  that correspond to unused subpatterns at the end of the
2309         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
2310         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
2311         matched.  The  return  from the function is 2, because the highest used         matched. The return from the function is 2, because  the  highest  used
2312         capturing subpattern number is 1. However, you can refer to the offsets         capturing subpattern number is 1. However, you can refer to the offsets
2313         for  the  second  and third capturing subpatterns if you wish (assuming         for the second and third capturing subpatterns if  you  wish  (assuming
2314         the vector is large enough, of course).         the vector is large enough, of course).
2315    
2316         Some convenience functions are provided  for  extracting  the  captured         Some  convenience  functions  are  provided for extracting the captured
2317         substrings as separate strings. These are described below.         substrings as separate strings. These are described below.
2318    
2319     Error return values from pcre_exec()     Error return values from pcre_exec()
2320    
2321         If  pcre_exec()  fails, it returns a negative number. The following are         If pcre_exec() fails, it returns a negative number. The  following  are
2322         defined in the header file:         defined in the header file:
2323    
2324           PCRE_ERROR_NOMATCH        (-1)           PCRE_ERROR_NOMATCH        (-1)
# Line 2290  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2327  MATCHING A PATTERN: THE TRADITIONAL FUNC
2327    
2328           PCRE_ERROR_NULL           (-2)           PCRE_ERROR_NULL           (-2)
2329    
2330         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
2331         ovecsize was not zero.         ovecsize was not zero.
2332    
2333           PCRE_ERROR_BADOPTION      (-3)           PCRE_ERROR_BADOPTION      (-3)
# Line 2299  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2336  MATCHING A PATTERN: THE TRADITIONAL FUNC
2336    
2337           PCRE_ERROR_BADMAGIC       (-4)           PCRE_ERROR_BADMAGIC       (-4)
2338    
2339         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,
2340         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
2341         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
2342         an environment with the other endianness. This is the error  that  PCRE         an  environment  with the other endianness. This is the error that PCRE
2343         gives when the magic number is not present.         gives when the magic number is not present.
2344    
2345           PCRE_ERROR_UNKNOWN_OPCODE (-5)           PCRE_ERROR_UNKNOWN_OPCODE (-5)
2346    
2347         While running the pattern match, an unknown item was encountered in the         While running the pattern match, an unknown item was encountered in the
2348         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
2349         overwriting of the compiled pattern.         overwriting of the compiled pattern.
2350    
2351           PCRE_ERROR_NOMEMORY       (-6)           PCRE_ERROR_NOMEMORY       (-6)
2352    
2353         If  a  pattern contains back references, but the ovector that is passed         If a pattern contains back references, but the ovector that  is  passed
2354         to pcre_exec() is not big enough to remember the referenced substrings,         to pcre_exec() is not big enough to remember the referenced substrings,
2355         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
2356         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
2357         memory is automatically freed at the end of matching.         memory is automatically freed at the end of matching.
2358    
2359         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().
2360         This can happen only when PCRE has been compiled with  --disable-stack-         This  can happen only when PCRE has been compiled with --disable-stack-
2361         for-recursion.         for-recursion.
2362    
2363           PCRE_ERROR_NOSUBSTRING    (-7)           PCRE_ERROR_NOSUBSTRING    (-7)
2364    
2365         This  error is used by the pcre_copy_substring(), pcre_get_substring(),         This error is used by the pcre_copy_substring(),  pcre_get_substring(),
2366         and  pcre_get_substring_list()  functions  (see  below).  It  is  never         and  pcre_get_substring_list()  functions  (see  below).  It  is  never
2367         returned by pcre_exec().         returned by pcre_exec().
2368    
2369           PCRE_ERROR_MATCHLIMIT     (-8)           PCRE_ERROR_MATCHLIMIT     (-8)
2370    
2371         The  backtracking  limit,  as  specified  by the match_limit field in a         The backtracking limit, as specified by  the  match_limit  field  in  a
2372         pcre_extra structure (or defaulted) was reached.  See  the  description         pcre_extra  structure  (or  defaulted) was reached. See the description
2373         above.         above.
2374    
2375           PCRE_ERROR_CALLOUT        (-9)           PCRE_ERROR_CALLOUT        (-9)
2376    
2377         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
2378         use by callout functions that want to yield a distinctive  error  code.         use  by  callout functions that want to yield a distinctive error code.
2379         See the pcrecallout documentation for details.         See the pcrecallout documentation for details.
2380    
2381           PCRE_ERROR_BADUTF8        (-10)           PCRE_ERROR_BADUTF8        (-10)
2382    
2383         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
2384         subject.         subject.
2385    
2386           PCRE_ERROR_BADUTF8_OFFSET (-11)           PCRE_ERROR_BADUTF8_OFFSET (-11)
2387    
2388         The UTF-8 byte sequence that was passed as a subject was valid, but the         The UTF-8 byte sequence that was passed as a subject was valid, but the
2389         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-
2390         ter.         ter.
2391    
2392           PCRE_ERROR_PARTIAL        (-12)           PCRE_ERROR_PARTIAL        (-12)
2393    
2394         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
2395         pcrepartial documentation for details of partial matching.         pcrepartial documentation for details of partial matching.
2396    
2397           PCRE_ERROR_BADPARTIAL     (-13)           PCRE_ERROR_BADPARTIAL     (-13)
2398    
2399         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
2400         PCRE_PARTIAL option was used with a compiled pattern  containing  items         PCRE_PARTIAL  option  was used with a compiled pattern containing items
2401         that  were  not  supported  for  partial  matching.  From  release 8.00         that were  not  supported  for  partial  matching.  From  release  8.00
2402         onwards, there are no restrictions on partial matching.         onwards, there are no restrictions on partial matching.
2403    
2404           PCRE_ERROR_INTERNAL       (-14)           PCRE_ERROR_INTERNAL       (-14)
2405    
2406         An unexpected internal error has occurred. This error could  be  caused         An  unexpected  internal error has occurred. This error could be caused
2407         by a bug in PCRE or by overwriting of the compiled pattern.         by a bug in PCRE or by overwriting of the compiled pattern.
2408    
2409           PCRE_ERROR_BADCOUNT       (-15)           PCRE_ERROR_BADCOUNT       (-15)
# Line 2376  MATCHING A PATTERN: THE TRADITIONAL FUNC Line 2413  MATCHING A PATTERN: THE TRADITIONAL FUNC
2413           PCRE_ERROR_RECURSIONLIMIT (-21)           PCRE_ERROR_RECURSIONLIMIT (-21)
2414    
2415         The internal recursion limit, as specified by the match_limit_recursion         The internal recursion limit, as specified by the match_limit_recursion
2416         field in a pcre_extra structure (or defaulted)  was  reached.  See  the         field  in  a  pcre_extra  structure (or defaulted) was reached. See the
2417         description above.         description above.
2418    
2419           PCRE_ERROR_BADNEWLINE     (-23)           PCRE_ERROR_BADNEWLINE     (-23)
# Line 2399  EXTRACTING CAPTURED SUBSTRINGS BY NUMBER Line 2436  EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
2436         int pcre_get_substring_list(const char *subject,         int pcre_get_substring_list(const char *subject,
2437              int *ovector, int stringcount, const char ***listptr);              int *ovector, int stringcount, const char ***listptr);
2438    
2439         Captured  substrings  can  be  accessed  directly  by using the offsets         Captured substrings can be  accessed  directly  by  using  the  offsets
2440         returned by pcre_exec() in  ovector.  For  convenience,  the  functions         returned  by  pcre_exec()  in  ovector.  For convenience, the functions
2441         pcre_copy_substring(),    pcre_get_substring(),    and    pcre_get_sub-         pcre_copy_substring(),    pcre_get_substring(),    and    pcre_get_sub-
2442         string_list() are provided for extracting captured substrings  as  new,         string_list()  are  provided for extracting captured substrings as new,
2443         separate,  zero-terminated strings. These functions identify substrings         separate, zero-terminated strings. These functions identify  substrings
2444         by number. The next section describes functions  for  extracting  named         by  number.  The  next section describes functions for extracting named
2445         substrings.         substrings.
2446    
2447         A  substring that contains a binary zero is correctly extracted and has         A substring that contains a binary zero is correctly extracted and  has
2448         a further zero added on the end, but the result is not, of course, a  C         a  further zero added on the end, but the result is not, of course, a C
2449         string.   However,  you  can  process such a string by referring to the         string.  However, you can process such a string  by  referring  to  the
2450         length that is  returned  by  pcre_copy_substring()  and  pcre_get_sub-         length  that  is  returned  by  pcre_copy_substring() and pcre_get_sub-
2451         string().  Unfortunately, the interface to pcre_get_substring_list() is         string().  Unfortunately, the interface to pcre_get_substring_list() is
2452         not adequate for handling strings containing binary zeros, because  the         not  adequate for handling strings containing binary zeros, because the
2453         end of the final string is not independently indicated.         end of the final string is not independently indicated.
2454    
2455         The  first  three  arguments  are the same for all three of these func-         The first three arguments are the same for all  three  of  these  func-
2456         tions: subject is the subject string that has  just  been  successfully         tions:  subject  is  the subject string that has just been successfully
2457         matched, ovector is a pointer to the vector of integer offsets that was         matched, ovector is a pointer to the vector of integer offsets that was
2458         passed to pcre_exec(), and stringcount is the number of substrings that         passed to pcre_exec(), and stringcount is the number of substrings that
2459         were  captured  by  the match, including the substring that matched the         were captured by the match, including the substring  that  matched  the
2460         entire regular expression. This is the value returned by pcre_exec() if         entire regular expression. This is the value returned by pcre_exec() if
2461         it  is greater than zero. If pcre_exec() returned zero, indicating that         it is greater than zero. If pcre_exec() returned zero, indicating  that
2462         it ran out of space in ovector, the value passed as stringcount  should         it  ran out of space in ovector, the value passed as stringcount should
2463         be the number of elements in the vector divided by three.         be the number of elements in the vector divided by three.
2464    
2465         The  functions pcre_copy_substring() and pcre_get_substring() extract a         The functions pcre_copy_substring() and pcre_get_substring() extract  a
2466         single substring, whose number is given as  stringnumber.  A  value  of         single  substring,  whose  number  is given as stringnumber. A value of
2467         zero  extracts  the  substring that matched the entire pattern, whereas         zero extracts the substring that matched the  entire  pattern,  whereas
2468         higher values  extract  the  captured  substrings.  For  pcre_copy_sub-         higher  values  extract  the  captured  substrings.  For pcre_copy_sub-
2469         string(),  the  string  is  placed  in buffer, whose length is given by         string(), the string is placed in buffer,  whose  length  is  given  by
2470         buffersize, while for pcre_get_substring() a new  block  of  memory  is         buffersize,  while  for  pcre_get_substring()  a new block of memory is
2471         obtained  via  pcre_malloc,  and its address is returned via stringptr.         obtained via pcre_malloc, and its address is  returned  via  stringptr.
2472         The yield of the function is the length of the  string,  not  including         The  yield  of  the function is the length of the string, not including
2473         the terminating zero, or one of these error codes:         the terminating zero, or one of these error codes:
2474    
2475           PCRE_ERROR_NOMEMORY       (-6)           PCRE_ERROR_NOMEMORY       (-6)
2476    
2477         The  buffer  was too small for pcre_copy_substring(), or the attempt to         The buffer was too small for pcre_copy_substring(), or the  attempt  to
2478         get memory failed for pcre_get_substring().         get memory failed for pcre_get_substring().
2479    
2480           PCRE_ERROR_NOSUBSTRING    (-7)           PCRE_ERROR_NOSUBSTRING    (-7)
2481    
2482         There is no substring whose number is stringnumber.         There is no substring whose number is stringnumber.
2483    
2484         The pcre_get_substring_list()  function  extracts  all  available  sub-         The  pcre_get_substring_list()  function  extracts  all  available sub-
2485         strings  and  builds  a list of pointers to them. All this is done in a         strings and builds a list of pointers to them. All this is  done  in  a
2486         single block of memory that is obtained via pcre_malloc. The address of         single block of memory that is obtained via pcre_malloc. The address of
2487         the  memory  block  is returned via listptr, which is also the start of         the memory block is returned via listptr, which is also  the  start  of
2488         the list of string pointers. The end of the list is marked  by  a  NULL         the  list  of  string pointers. The end of the list is marked by a NULL
2489         pointer.  The  yield  of  the function is zero if all went well, or the         pointer. The yield of the function is zero if all  went  well,  or  the
2490         error code         error code
2491    
2492           PCRE_ERROR_NOMEMORY       (-6)           PCRE_ERROR_NOMEMORY       (-6)
2493    
2494         if the attempt to get the memory block failed.         if the attempt to get the memory block failed.
2495    
2496         When any of these functions encounter a substring that is unset,  which         When  any of these functions encounter a substring that is unset, which
2497         can  happen  when  capturing subpattern number n+1 matches some part of         can happen when capturing subpattern number n+1 matches  some  part  of
2498         the subject, but subpattern n has not been used at all, they return  an         the  subject, but subpattern n has not been used at all, they return an
2499         empty string. This can be distinguished from a genuine zero-length sub-         empty string. This can be distinguished from a genuine zero-length sub-
2500         string by inspecting the appropriate offset in ovector, which is  nega-         string  by inspecting the appropriate offset in ovector, which is nega-
2501         tive for unset substrings.         tive for unset substrings.
2502    
2503         The  two convenience functions pcre_free_substring() and pcre_free_sub-         The two convenience functions pcre_free_substring() and  pcre_free_sub-
2504         string_list() can be used to free the memory  returned  by  a  previous         string_list()  can  be  used  to free the memory returned by a previous
2505         call  of  pcre_get_substring()  or  pcre_get_substring_list(),  respec-         call  of  pcre_get_substring()  or  pcre_get_substring_list(),  respec-
2506         tively. They do nothing more than  call  the  function  pointed  to  by         tively.  They  do  nothing  more  than  call the function pointed to by
2507         pcre_free,  which  of course could be called directly from a C program.         pcre_free, which of course could be called directly from a  C  program.
2508         However, PCRE is used in some situations where it is linked via a  spe-         However,  PCRE is used in some situations where it is linked via a spe-
2509         cial   interface  to  another  programming  language  that  cannot  use         cial  interface  to  another  programming  language  that  cannot   use
2510         pcre_free directly; it is for these cases that the functions  are  pro-         pcre_free  directly;  it is for these cases that the functions are pro-
2511         vided.         vided.
2512    
2513    
# Line 2489  EXTRACTING CAPTURED SUBSTRINGS BY NAME Line 2526  EXTRACTING CAPTURED SUBSTRINGS BY NAME
2526              int stringcount, const char *stringname,              int stringcount, const char *stringname,
2527              const char **stringptr);              const char **stringptr);
2528    
2529         To  extract a substring by name, you first have to find associated num-         To extract a substring by name, you first have to find associated  num-
2530         ber.  For example, for this pattern         ber.  For example, for this pattern
2531    
2532           (a+)b(?<xxx>\d+)...           (a+)b(?<xxx>\d+)...
# Line 2498  EXTRACTING CAPTURED SUBSTRINGS BY NAME Line 2535  EXTRACTING CAPTURED SUBSTRINGS BY NAME
2535         be unique (PCRE_DUPNAMES was not set), you can find the number from the         be unique (PCRE_DUPNAMES was not set), you can find the number from the
2536         name by calling pcre_get_stringnumber(). The first argument is the com-         name by calling pcre_get_stringnumber(). The first argument is the com-
2537         piled pattern, and the second is the name. The yield of the function is         piled pattern, and the second is the name. The yield of the function is
2538         the subpattern number, or PCRE_ERROR_NOSUBSTRING (-7) if  there  is  no         the  subpattern  number,  or PCRE_ERROR_NOSUBSTRING (-7) if there is no
2539         subpattern of that name.         subpattern of that name.
2540    
2541         Given the number, you can extract the substring directly, or use one of         Given the number, you can extract the substring directly, or use one of
2542         the functions described in the previous section. For convenience, there         the functions described in the previous section. For convenience, there
2543         are also two functions that do the whole job.         are also two functions that do the whole job.
2544    
2545         Most    of    the    arguments   of   pcre_copy_named_substring()   and         Most   of   the   arguments    of    pcre_copy_named_substring()    and
2546         pcre_get_named_substring() are the same  as  those  for  the  similarly         pcre_get_named_substring()  are  the  same  as  those for the similarly
2547         named  functions  that extract by number. As these are described in the         named functions that extract by number. As these are described  in  the
2548         previous section, they are not re-described here. There  are  just  two         previous  section,  they  are not re-described here. There are just two
2549         differences:         differences:
2550    
2551         First,  instead  of a substring number, a substring name is given. Sec-         First, instead of a substring number, a substring name is  given.  Sec-
2552         ond, there is an extra argument, given at the start, which is a pointer         ond, there is an extra argument, given at the start, which is a pointer
2553         to  the compiled pattern. This is needed in order to gain access to the         to the compiled pattern. This is needed in order to gain access to  the
2554         name-to-number translation table.         name-to-number translation table.
2555    
2556         These functions call pcre_get_stringnumber(), and if it succeeds,  they         These  functions call pcre_get_stringnumber(), and if it succeeds, they
2557         then  call  pcre_copy_substring() or pcre_get_substring(), as appropri-         then call pcre_copy_substring() or pcre_get_substring(),  as  appropri-
2558         ate. NOTE: If PCRE_DUPNAMES is set and there are duplicate  names,  the         ate.  NOTE:  If PCRE_DUPNAMES is set and there are duplicate names, the
2559         behaviour may not be what you want (see the next section).         behaviour may not be what you want (see the next section).
2560    
2561         Warning: If the pattern uses the (?| feature to set up multiple subpat-         Warning: If the pattern uses the (?| feature to set up multiple subpat-
2562         terns with the same number, as described in the  section  on  duplicate         terns  with  the  same number, as described in the section on duplicate
2563         subpattern  numbers  in  the  pcrepattern page, you cannot use names to         subpattern numbers in the pcrepattern page, you  cannot  use  names  to
2564         distinguish the different subpatterns, because names are  not  included         distinguish  the  different subpatterns, because names are not included
2565         in  the compiled code. The matching process uses only numbers. For this         in the compiled code. The matching process uses only numbers. For  this
2566         reason, the use of different names for subpatterns of the  same  number         reason,  the  use of different names for subpatterns of the same number
2567         causes an error at compile time.         causes an error at compile time.
2568    
2569    
# Line 2535  DUPLICATE SUBPATTERN NAMES Line 2572  DUPLICATE SUBPATTERN NAMES
2572         int pcre_get_stringtable_entries(const pcre *code,         int pcre_get_stringtable_entries(const pcre *code,
2573              const char *name, char **first, char **last);              const char *name, char **first, char **last);
2574    
2575         When  a  pattern  is  compiled with the PCRE_DUPNAMES option, names for         When a pattern is compiled with the  PCRE_DUPNAMES  option,  names  for
2576         subpatterns are not required to be unique. (Duplicate names are  always         subpatterns  are not required to be unique. (Duplicate names are always
2577         allowed  for subpatterns with the same number, created by using the (?|         allowed for subpatterns with the same number, created by using the  (?|
2578         feature. Indeed, if such subpatterns are named, they  are  required  to         feature.  Indeed,  if  such subpatterns are named, they are required to
2579         use the same names.)         use the same names.)
2580    
2581         Normally, patterns with duplicate names are such that in any one match,         Normally, patterns with duplicate names are such that in any one match,
2582         only one of the named subpatterns participates. An example is shown  in         only  one of the named subpatterns participates. An example is shown in
2583         the pcrepattern documentation.         the pcrepattern documentation.
2584    
2585         When    duplicates   are   present,   pcre_copy_named_substring()   and         When   duplicates   are   present,   pcre_copy_named_substring()    and
2586         pcre_get_named_substring() return the first substring corresponding  to         pcre_get_named_substring()  return the first substring corresponding to
2587         the  given  name  that  is set. If none are set, PCRE_ERROR_NOSUBSTRING         the given name that is set. If  none  are  set,  PCRE_ERROR_NOSUBSTRING
2588         (-7) is returned; no  data  is  returned.  The  pcre_get_stringnumber()         (-7)  is  returned;  no  data  is returned. The pcre_get_stringnumber()
2589         function  returns one of the numbers that are associated with the name,         function returns one of the numbers that are associated with the  name,
2590         but it is not defined which it is.         but it is not defined which it is.
2591    
2592         If you want to get full details of all captured substrings for a  given         If  you want to get full details of all captured substrings for a given
2593         name,  you  must  use  the pcre_get_stringtable_entries() function. The         name, you must use  the  pcre_get_stringtable_entries()  function.  The
2594         first argument is the compiled pattern, and the second is the name. The         first argument is the compiled pattern, and the second is the name. The
2595         third  and  fourth  are  pointers to variables which are updated by the         third and fourth are pointers to variables which  are  updated  by  the
2596         function. After it has run, they point to the first and last entries in         function. After it has run, they point to the first and last entries in
2597         the  name-to-number  table  for  the  given  name.  The function itself         the name-to-number table  for  the  given  name.  The  function  itself
2598         returns the length of each entry,  or  PCRE_ERROR_NOSUBSTRING  (-7)  if         returns  the  length  of  each entry, or PCRE_ERROR_NOSUBSTRING (-7) if
2599         there  are none. The format of the table is described above in the sec-         there are none. The format of the table is described above in the  sec-
2600         tion entitled Information about a  pattern.   Given  all  the  relevant         tion  entitled  Information  about  a  pattern.  Given all the relevant
2601         entries  for the name, you can extract each of their numbers, and hence         entries for the name, you can extract each of their numbers, and  hence
2602         the captured data, if any.         the captured data, if any.
2603    
2604    
2605  FINDING ALL POSSIBLE MATCHES  FINDING ALL POSSIBLE MATCHES
2606    
2607         The traditional matching function uses a  similar  algorithm  to  Perl,         The  traditional  matching  function  uses a similar algorithm to Perl,
2608         which stops when it finds the first match, starting at a given point in         which stops when it finds the first match, starting at a given point in
2609         the subject. If you want to find all possible matches, or  the  longest         the  subject.  If you want to find all possible matches, or the longest
2610         possible  match,  consider using the alternative matching function (see         possible match, consider using the alternative matching  function  (see
2611         below) instead. If you cannot use the alternative function,  but  still         below)  instead.  If you cannot use the alternative function, but still
2612         need  to  find all possible matches, you can kludge it up by making use         need to find all possible matches, you can kludge it up by  making  use
2613         of the callout facility, which is described in the pcrecallout documen-         of the callout facility, which is described in the pcrecallout documen-
2614         tation.         tation.
2615    
2616         What you have to do is to insert a callout right at the end of the pat-         What you have to do is to insert a callout right at the end of the pat-
2617         tern.  When your callout function is called, extract and save the  cur-         tern.   When your callout function is called, extract and save the cur-
2618         rent  matched  substring.  Then  return  1, which forces pcre_exec() to         rent matched substring. Then return  1,  which  forces  pcre_exec()  to
2619         backtrack and try other alternatives. Ultimately, when it runs  out  of         backtrack  and  try other alternatives. Ultimately, when it runs out of
2620         matches, pcre_exec() will yield PCRE_ERROR_NOMATCH.         matches, pcre_exec() will yield PCRE_ERROR_NOMATCH.
2621    
2622    
# Line 2590  MATCHING A PATTERN: THE ALTERNATIVE FUNC Line 2627  MATCHING A PATTERN: THE ALTERNATIVE FUNC
2627              int options, int *ovector, int ovecsize,              int options, int *ovector, int ovecsize,
2628              int *workspace, int wscount);              int *workspace, int wscount);
2629    
2630         The  function  pcre_dfa_exec()  is  called  to  match  a subject string         The function pcre_dfa_exec()  is  called  to  match  a  subject  string
2631         against a compiled pattern, using a matching algorithm that  scans  the         against  a  compiled pattern, using a matching algorithm that scans the
2632         subject  string  just  once, and does not backtrack. This has different         subject string just once, and does not backtrack.  This  has  different
2633         characteristics to the normal algorithm, and  is  not  compatible  with         characteristics  to  the  normal  algorithm, and is not compatible with
2634         Perl.  Some  of the features of PCRE patterns are not supported. Never-         Perl. Some of the features of PCRE patterns are not  supported.  Never-
2635         theless, there are times when this kind of matching can be useful.  For         theless,  there are times when this kind of matching can be useful. For
2636         a  discussion  of  the  two matching algorithms, and a list of features         a discussion of the two matching algorithms, and  a  list  of  features
2637         that pcre_dfa_exec() does not support, see the pcrematching  documenta-         that  pcre_dfa_exec() does not support, see the pcrematching documenta-
2638         tion.         tion.
2639    
2640         The  arguments  for  the  pcre_dfa_exec()  function are the same as for         The arguments for the pcre_dfa_exec() function  are  the  same  as  for
2641         pcre_exec(), plus two extras. The ovector argument is used in a differ-         pcre_exec(), plus two extras. The ovector argument is used in a differ-
2642         ent  way,  and  this is described below. The other common arguments are         ent way, and this is described below. The other  common  arguments  are
2643         used in the same way as for pcre_exec(), so their  description  is  not         used  in  the  same way as for pcre_exec(), so their description is not
2644         repeated here.         repeated here.
2645    
2646         The  two  additional  arguments provide workspace for the function. The         The two additional arguments provide workspace for  the  function.  The
2647         workspace vector should contain at least 20 elements. It  is  used  for         workspace  vector  should  contain at least 20 elements. It is used for
2648         keeping  track  of  multiple  paths  through  the  pattern  tree.  More         keeping  track  of  multiple  paths  through  the  pattern  tree.  More
2649         workspace will be needed for patterns and subjects where  there  are  a         workspace  will  be  needed for patterns and subjects where there are a
2650         lot of potential matches.         lot of potential matches.
2651    
2652         Here is an example of a simple call to pcre_dfa_exec():         Here is an example of a simple call to pcre_dfa_exec():
# Line 2631  MATCHING A PATTERN: THE ALTERNATIVE FUNC Line 2668  MATCHING A PATTERN: THE ALTERNATIVE FUNC
2668    
2669     Option bits for pcre_dfa_exec()     Option bits for pcre_dfa_exec()
2670    
2671         The  unused  bits  of  the options argument for pcre_dfa_exec() must be         The unused bits of the options argument  for  pcre_dfa_exec()  must  be
2672         zero. The only bits  that  may  be  set  are  PCRE_ANCHORED,  PCRE_NEW-         zero.  The  only  bits  that  may  be  set are PCRE_ANCHORED, PCRE_NEW-
2673         LINE_xxx,        PCRE_NOTBOL,        PCRE_NOTEOL,        PCRE_NOTEMPTY,         LINE_xxx,        PCRE_NOTBOL,        PCRE_NOTEOL,        PCRE_NOTEMPTY,
2674         PCRE_NOTEMPTY_ATSTART,      PCRE_NO_UTF8_CHECK,       PCRE_BSR_ANYCRLF,         PCRE_NOTEMPTY_ATSTART,       PCRE_NO_UTF8_CHECK,      PCRE_BSR_ANYCRLF,
2675         PCRE_BSR_UNICODE,  PCRE_NO_START_OPTIMIZE, PCRE_PARTIAL_HARD, PCRE_PAR-         PCRE_BSR_UNICODE, PCRE_NO_START_OPTIMIZE, PCRE_PARTIAL_HARD,  PCRE_PAR-
2676         TIAL_SOFT, PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART.  All but  the  last         TIAL_SOFT,  PCRE_DFA_SHORTEST,  and PCRE_DFA_RESTART.  All but the last
2677         four  of  these  are  exactly  the  same  as  for pcre_exec(), so their         four of these are  exactly  the  same  as  for  pcre_exec(),  so  their
2678         description is not repeated here.         description is not repeated here.
2679    
2680           PCRE_PARTIAL_HARD           PCRE_PARTIAL_HARD
2681           PCRE_PARTIAL_SOFT           PCRE_PARTIAL_SOFT
2682    
2683         These have the same general effect as they do for pcre_exec(), but  the         These  have the same general effect as they do for pcre_exec(), but the
2684         details  are  slightly  different.  When  PCRE_PARTIAL_HARD  is set for         details are slightly  different.  When  PCRE_PARTIAL_HARD  is  set  for
2685         pcre_dfa_exec(), it returns PCRE_ERROR_PARTIAL if the end of  the  sub-         pcre_dfa_exec(),  it  returns PCRE_ERROR_PARTIAL if the end of the sub-
2686         ject  is  reached  and there is still at least one matching possibility         ject is reached and there is still at least  one  matching  possibility
2687         that requires additional characters. This happens even if some complete         that requires additional characters. This happens even if some complete
2688         matches have also been found. When PCRE_PARTIAL_SOFT is set, the return         matches have also been found. When PCRE_PARTIAL_SOFT is set, the return
2689         code PCRE_ERROR_NOMATCH is converted into PCRE_ERROR_PARTIAL if the end         code PCRE_ERROR_NOMATCH is converted into PCRE_ERROR_PARTIAL if the end
2690         of  the  subject  is  reached, there have been no complete matches, but         of the subject is reached, there have been  no  complete  matches,  but
2691         there is still at least one matching possibility. The  portion  of  the         there  is  still  at least one matching possibility. The portion of the
2692         string  that  was inspected when the longest partial match was found is         string that was inspected when the longest partial match was  found  is
2693         set as the first matching string in both cases.         set as the first matching string in both cases.
2694    
2695           PCRE_DFA_SHORTEST           PCRE_DFA_SHORTEST
2696    
2697         Setting the PCRE_DFA_SHORTEST option causes the matching  algorithm  to         Setting  the  PCRE_DFA_SHORTEST option causes the matching algorithm to
2698         stop as soon as it has found one match. Because of the way the alterna-         stop as soon as it has found one match. Because of the way the alterna-
2699         tive algorithm works, this is necessarily the shortest  possible  match         tive  algorithm  works, this is necessarily the shortest possible match
2700         at the first possible matching point in the subject string.         at the first possible matching point in the subject string.
2701    
2702           PCRE_DFA_RESTART           PCRE_DFA_RESTART
2703    
2704         When pcre_dfa_exec() returns a partial match, it is possible to call it         When pcre_dfa_exec() returns a partial match, it is possible to call it
2705         again, with additional subject characters, and have  it  continue  with         again,  with  additional  subject characters, and have it continue with
2706         the  same match. The PCRE_DFA_RESTART option requests this action; when         the same match. The PCRE_DFA_RESTART option requests this action;  when
2707         it is set, the workspace and wscount options must  reference  the  same         it  is  set,  the workspace and wscount options must reference the same
2708         vector  as  before  because data about the match so far is left in them         vector as before because data about the match so far is  left  in  them
2709         after a partial match. There is more discussion of this facility in the         after a partial match. There is more discussion of this facility in the
2710         pcrepartial documentation.         pcrepartial documentation.
2711    
2712     Successful returns from pcre_dfa_exec()     Successful returns from pcre_dfa_exec()
2713    
2714         When  pcre_dfa_exec()  succeeds, it may have matched more than one sub-         When pcre_dfa_exec() succeeds, it may have matched more than  one  sub-
2715         string in the subject. Note, however, that all the matches from one run         string in the subject. Note, however, that all the matches from one run
2716         of  the  function  start  at the same point in the subject. The shorter         of the function start at the same point in  the  subject.  The  shorter
2717         matches are all initial substrings of the longer matches. For  example,         matches  are all initial substrings of the longer matches. For example,
2718         if the pattern         if the pattern
2719    
2720           <.*>           <.*>
# Line 2692  MATCHING A PATTERN: THE ALTERNATIVE FUNC Line 2729  MATCHING A PATTERN: THE ALTERNATIVE FUNC
2729           <something> <something else>           <something> <something else>
2730           <something> <something else> <something further>           <something> <something else> <something further>
2731    
2732         On  success,  the  yield of the function is a number greater than zero,         On success, the yield of the function is a number  greater  than  zero,
2733         which is the number of matched substrings.  The  substrings  themselves         which  is  the  number of matched substrings. The substrings themselves
2734         are  returned  in  ovector. Each string uses two elements; the first is         are returned in ovector. Each string uses two elements;  the  first  is
2735         the offset to the start, and the second is the offset to  the  end.  In         the  offset  to  the start, and the second is the offset to the end. In
2736         fact,  all  the  strings  have the same start offset. (Space could have         fact, all the strings have the same start  offset.  (Space  could  have
2737         been saved by giving this only once, but it was decided to retain  some         been  saved by giving this only once, but it was decided to retain some
2738         compatibility  with  the  way pcre_exec() returns data, even though the         compatibility with the way pcre_exec() returns data,  even  though  the
2739         meaning of the strings is different.)         meaning of the strings is different.)
2740    
2741         The strings are returned in reverse order of length; that is, the long-         The strings are returned in reverse order of length; that is, the long-
2742         est  matching  string is given first. If there were too many matches to         est matching string is given first. If there were too many  matches  to
2743         fit into ovector, the yield of the function is zero, and the vector  is         fit  into ovector, the yield of the function is zero, and the vector is
2744         filled with the longest matches.         filled with the longest matches.
2745    
2746     Error returns from pcre_dfa_exec()     Error returns from pcre_dfa_exec()
2747    
2748         The  pcre_dfa_exec()  function returns a negative number when it fails.         The pcre_dfa_exec() function returns a negative number when  it  fails.
2749         Many of the errors are the same  as  for  pcre_exec(),  and  these  are         Many  of  the  errors  are  the  same as for pcre_exec(), and these are
2750         described  above.   There are in addition the following errors that are         described above.  There are in addition the following errors  that  are
2751         specific to pcre_dfa_exec():         specific to pcre_dfa_exec():
2752    
2753           PCRE_ERROR_DFA_UITEM      (-16)           PCRE_ERROR_DFA_UITEM      (-16)
2754    
2755         This return is given if pcre_dfa_exec() encounters an item in the  pat-         This  return is given if pcre_dfa_exec() encounters an item in the pat-
2756         tern  that  it  does not support, for instance, the use of \C or a back         tern that it does not support, for instance, the use of \C  or  a  back
2757         reference.         reference.
2758    
2759           PCRE_ERROR_DFA_UCOND      (-17)           PCRE_ERROR_DFA_UCOND      (-17)
2760    
2761         This return is given if pcre_dfa_exec()  encounters  a  condition  item         This  return  is  given  if pcre_dfa_exec() encounters a condition item
2762         that  uses  a back reference for the condition, or a test for recursion         that uses a back reference for the condition, or a test  for  recursion
2763         in a specific group. These are not supported.         in a specific group. These are not supported.
2764    
2765           PCRE_ERROR_DFA_UMLIMIT    (-18)           PCRE_ERROR_DFA_UMLIMIT    (-18)
2766    
2767         This return is given if pcre_dfa_exec() is called with an  extra  block         This  return  is given if pcre_dfa_exec() is called with an extra block
2768         that contains a setting of the match_limit field. This is not supported         that contains a setting of the match_limit field. This is not supported
2769         (it is meaningless).         (it is meaningless).
2770    
2771           PCRE_ERROR_DFA_WSSIZE     (-19)           PCRE_ERROR_DFA_WSSIZE     (-19)
2772    
2773         This return is given if  pcre_dfa_exec()  runs  out  of  space  in  the         This  return  is  given  if  pcre_dfa_exec()  runs  out of space in the
2774         workspace vector.         workspace vector.
2775    
2776           PCRE_ERROR_DFA_RECURSE    (-20)           PCRE_ERROR_DFA_RECURSE    (-20)
2777    
2778         When  a  recursive subpattern is processed, the matching function calls         When a recursive subpattern is processed, the matching  function  calls
2779         itself recursively, using private vectors for  ovector  and  workspace.         itself  recursively,  using  private vectors for ovector and workspace.
2780         This  error  is  given  if  the output vector is not large enough. This         This error is given if the output vector  is  not  large  enough.  This
2781         should be extremely rare, as a vector of size 1000 is used.         should be extremely rare, as a vector of size 1000 is used.
2782    
2783    
2784  SEE ALSO  SEE ALSO
2785    
2786         pcrebuild(3), pcrecallout(3), pcrecpp(3)(3), pcrematching(3),  pcrepar-         pcrebuild(3),  pcrecallout(3), pcrecpp(3)(3), pcrematching(3), pcrepar-
2787         tial(3), pcreposix(3), pcreprecompile(3), pcresample(3), pcrestack(3).         tial(3), pcreposix(3), pcreprecompile(3), pcresample(3), pcrestack(3).
2788    
2789    
# Line 2759  AUTHOR Line 2796  AUTHOR
2796    
2797  REVISION  REVISION
2798    
2799         Last updated: 15 June 2010         Last updated: 21 June 2010
2800         Copyright (c) 1997-2010 University of Cambridge.         Copyright (c) 1997-2010 University of Cambridge.
2801  ------------------------------------------------------------------------------  ------------------------------------------------------------------------------
2802    

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