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revision 921 by ph10, Sat Feb 18 18:45:55 2012 UTC revision 1022 by ph10, Tue Aug 28 12:28:15 2012 UTC
# Line 1  Line 1 
1  .TH PCREAPI 3  .TH PCREAPI 3 "28 August 2012" "PCRE 8.32"
2  .SH NAME  .SH NAME
3  PCRE - Perl-compatible regular expressions  PCRE - Perl-compatible regular expressions
4  .sp  .sp
# Line 302  PCRE supports five different conventions Line 302  PCRE supports five different conventions
302  strings: a single CR (carriage return) character, a single LF (linefeed)  strings: a single CR (carriage return) character, a single LF (linefeed)
303  character, the two-character sequence CRLF, any of the three preceding, or any  character, the two-character sequence CRLF, any of the three preceding, or any
304  Unicode newline sequence. The Unicode newline sequences are the three just  Unicode newline sequence. The Unicode newline sequences are the three just
305  mentioned, plus the single characters VT (vertical tab, U+000B), FF (formfeed,  mentioned, plus the single characters VT (vertical tab, U+000B), FF (form feed,
306  U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS  U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
307  (paragraph separator, U+2029).  (paragraph separator, U+2029).
308  .P  .P
# Line 526  documentation). For those options that c Line 526  documentation). For those options that c
526  the pattern, the contents of the \fIoptions\fP argument specifies their  the pattern, the contents of the \fIoptions\fP argument specifies their
527  settings at the start of compilation and execution. The PCRE_ANCHORED,  settings at the start of compilation and execution. The PCRE_ANCHORED,
528  PCRE_BSR_\fIxxx\fP, PCRE_NEWLINE_\fIxxx\fP, PCRE_NO_UTF8_CHECK, and  PCRE_BSR_\fIxxx\fP, PCRE_NEWLINE_\fIxxx\fP, PCRE_NO_UTF8_CHECK, and
529  PCRE_NO_START_OPT options can be set at the time of matching as well as at  PCRE_NO_START_OPTIMIZE options can be set at the time of matching as well as at
530  compile time.  compile time.
531  .P  .P
532  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
# Line 642  documentation. Line 642  documentation.
642  .sp  .sp
643    PCRE_EXTENDED    PCRE_EXTENDED
644  .sp  .sp
645  If this bit is set, whitespace data characters in the pattern are totally  If this bit is set, white space data characters in the pattern are totally
646  ignored except when escaped or inside a character class. Whitespace does not  ignored except when escaped or inside a character class. White space does not
647  include the VT character (code 11). In addition, characters between an  include the VT character (code 11). In addition, characters between an
648  unescaped # outside a character class and the next newline, inclusive, are also  unescaped # outside a character class and the next newline, inclusive, are also
649  ignored. This is equivalent to Perl's /x option, and it can be changed within a  ignored. This is equivalent to Perl's /x option, and it can be changed within a
# Line 661  comment is a literal newline sequence in Line 661  comment is a literal newline sequence in
661  happen to represent a newline do not count.  happen to represent a newline do not count.
662  .P  .P
663  This option makes it possible to include comments inside complicated patterns.  This option makes it possible to include comments inside complicated patterns.
664  Note, however, that this applies only to data characters. Whitespace characters  Note, however, that this applies only to data characters. White space characters
665  may never appear within special character sequences in a pattern, for example  may never appear within special character sequences in a pattern, for example
666  within the sequence (?( that introduces a conditional subpattern.  within the sequence (?( that introduces a conditional subpattern.
667  .sp  .sp
# Line 741  CRLF sequence. Setting PCRE_NEWLINE_ANYC Line 741  CRLF sequence. Setting PCRE_NEWLINE_ANYC
741  preceding sequences should be recognized. Setting PCRE_NEWLINE_ANY specifies  preceding sequences should be recognized. Setting PCRE_NEWLINE_ANY specifies
742  that any Unicode newline sequence should be recognized. The Unicode newline  that any Unicode newline sequence should be recognized. The Unicode newline
743  sequences are the three just mentioned, plus the single characters VT (vertical  sequences are the three just mentioned, plus the single characters VT (vertical
744  tab, U+000B), FF (formfeed, U+000C), NEL (next line, U+0085), LS (line  tab, U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line
745  separator, U+2028), and PS (paragraph separator, U+2029). For the 8-bit  separator, U+2028), and PS (paragraph separator, U+2029). For the 8-bit
746  library, the last two are recognized only in UTF-8 mode.  library, the last two are recognized only in UTF-8 mode.
747  .P  .P
# Line 753  PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is Line 753  PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is
753  other combinations may yield unused numbers and cause an error.  other combinations may yield unused numbers and cause an error.
754  .P  .P
755  The only time that a line break in a pattern is specially recognized when  The only time that a line break in a pattern is specially recognized when
756  compiling is when PCRE_EXTENDED is set. CR and LF are whitespace characters,  compiling is when PCRE_EXTENDED is set. CR and LF are white space characters,
757  and so are ignored in this mode. Also, an unescaped # outside a character class  and so are ignored in this mode. Also, an unescaped # outside a character class
758  indicates a comment that lasts until after the next line break sequence. In  indicates a comment that lasts until after the next line break sequence. In
759  other circumstances, line break sequences in patterns are treated as literal  other circumstances, line break sequences in patterns are treated as literal
# Line 926  fallen out of use. To avoid confusion, t Line 926  fallen out of use. To avoid confusion, t
926    72  too many forward references    72  too many forward references
927    73  disallowed Unicode code point (>= 0xd800 && <= 0xdfff)    73  disallowed Unicode code point (>= 0xd800 && <= 0xdfff)
928    74  invalid UTF-16 string (specifically UTF-16)    74  invalid UTF-16 string (specifically UTF-16)
929      75  name is too long in (*MARK), (*PRUNE), (*SKIP), or (*THEN)
930      76  character value in \eu.... sequence is too large
931  .sp  .sp
932  The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may  The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may
933  be used if the limits were changed when PCRE was built.  be used if the limits were changed when PCRE was built.
# Line 958  below Line 960  below
960  in the section on matching a pattern.  in the section on matching a pattern.
961  .P  .P
962  If studying the pattern does not produce any useful information,  If studying the pattern does not produce any useful information,
963  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program  \fBpcre_study()\fP returns NULL by default. In that circumstance, if the
964  wants to pass any of the other fields to \fBpcre_exec()\fP or  calling program wants to pass any of the other fields to \fBpcre_exec()\fP or
965  \fBpcre_dfa_exec()\fP, it must set up its own \fBpcre_extra\fP block.  \fBpcre_dfa_exec()\fP, it must set up its own \fBpcre_extra\fP block. However,
966    if \fBpcre_study()\fP is called with the PCRE_STUDY_EXTRA_NEEDED option, it
967    returns a \fBpcre_extra\fP block even if studying did not find any additional
968    information. It may still return NULL, however, if an error occurs in
969    \fBpcre_study()\fP.
970  .P  .P
971  The second argument of \fBpcre_study()\fP contains option bits. There are three  The second argument of \fBpcre_study()\fP contains option bits. There are three
972  options:  further options in addition to PCRE_STUDY_EXTRA_NEEDED:
973  .sp  .sp
974    PCRE_STUDY_JIT_COMPILE    PCRE_STUDY_JIT_COMPILE
975    PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE    PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
976    PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE    PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
977  .sp  .sp
978  If any of these are set, and the just-in-time compiler is available, the  If any of these are set, and the just-in-time compiler is available, the
979  pattern is further compiled into machine code that executes much faster than  pattern is further compiled into machine code that executes much faster than
980  the \fBpcre_exec()\fP interpretive matching function. If the just-in-time  the \fBpcre_exec()\fP interpretive matching function. If the just-in-time
981  compiler is not available, these options are ignored. All other bits in the  compiler is not available, these options are ignored. All undefined bits in the
982  \fIoptions\fP argument must be zero.  \fIoptions\fP argument must be zero.
983  .P  .P
984  JIT compilation is a heavyweight optimization. It can take some time for  JIT compilation is a heavyweight optimization. It can take some time for
# Line 1020  real application there should be tests f Line 1026  real application there should be tests f
1026  Studying a pattern does two things: first, a lower bound for the length of  Studying a pattern does two things: first, a lower bound for the length of
1027  subject string that is needed to match the pattern is computed. This does not  subject string that is needed to match the pattern is computed. This does not
1028  mean that there are any strings of that length that match, but it does  mean that there are any strings of that length that match, but it does
1029  guarantee that no shorter strings match. The value is used by  guarantee that no shorter strings match. The value is used to avoid wasting
1030  \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP to avoid wasting time by trying to  time by trying to match strings that are shorter than the lower bound. You can
1031  match strings that are shorter than the lower bound. You can find out the value  find out the value in a calling program via the \fBpcre_fullinfo()\fP function.
 in a calling program via the \fBpcre_fullinfo()\fP function.  
1032  .P  .P
1033  Studying a pattern is also useful for non-anchored patterns that do not have a  Studying a pattern is also useful for non-anchored patterns that do not have a
1034  single fixed starting character. A bitmap of possible starting bytes is  single fixed starting character. A bitmap of possible starting bytes is
# Line 1235  only if it follows something of variable Line 1240  only if it follows something of variable
1240  /^a\ed+z\ed+/ the returned value is "z", but for /^a\edz\ed/ the returned value  /^a\ed+z\ed+/ the returned value is "z", but for /^a\edz\ed/ the returned value
1241  is -1.  is -1.
1242  .sp  .sp
1243      PCRE_INFO_MAXLOOKBEHIND
1244    .sp
1245    Return the number of characters (NB not bytes) in the longest lookbehind
1246    assertion in the pattern. Note that the simple assertions \eb and \eB require a
1247    one-character lookbehind. This information is useful when doing multi-segment
1248    matching using the partial matching facilities.
1249    .sp
1250    PCRE_INFO_MINLENGTH    PCRE_INFO_MINLENGTH
1251  .sp  .sp
1252  If the pattern was studied and a minimum length for matching subject strings  If the pattern was studied and a minimum length for matching subject strings
# Line 1465  fields (not necessarily in this order): Line 1477  fields (not necessarily in this order):
1477  In the 16-bit version of this structure, the \fImark\fP field has type  In the 16-bit version of this structure, the \fImark\fP field has type
1478  "PCRE_UCHAR16 **".  "PCRE_UCHAR16 **".
1479  .P  .P
1480  The \fIflags\fP field is a bitmap that specifies which of the other fields  The \fIflags\fP field is used to specify which of the other fields are set. The
1481  are set. The flag bits are:  flag bits are:
1482  .sp  .sp
1483    PCRE_EXTRA_STUDY_DATA    PCRE_EXTRA_CALLOUT_DATA
1484    PCRE_EXTRA_EXECUTABLE_JIT    PCRE_EXTRA_EXECUTABLE_JIT
1485      PCRE_EXTRA_MARK
1486    PCRE_EXTRA_MATCH_LIMIT    PCRE_EXTRA_MATCH_LIMIT
1487    PCRE_EXTRA_MATCH_LIMIT_RECURSION    PCRE_EXTRA_MATCH_LIMIT_RECURSION
1488    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_STUDY_DATA
1489    PCRE_EXTRA_TABLES    PCRE_EXTRA_TABLES
   PCRE_EXTRA_MARK  
1490  .sp  .sp
1491  Other flag bits should be set to zero. The \fIstudy_data\fP field and sometimes  Other flag bits should be set to zero. The \fIstudy_data\fP field and sometimes
1492  the \fIexecutable_jit\fP field are set in the \fBpcre_extra\fP block that is  the \fIexecutable_jit\fP field are set in the \fBpcre_extra\fP block that is
1493  returned by \fBpcre_study()\fP, together with the appropriate flag bits. You  returned by \fBpcre_study()\fP, together with the appropriate flag bits. You
1494  should not set these yourself, but you may add to the block by setting the  should not set these yourself, but you may add to the block by setting other
1495  other fields and their corresponding flag bits.  fields and their corresponding flag bits.
1496  .P  .P
1497  The \fImatch_limit\fP field provides a means of preventing PCRE from using up a  The \fImatch_limit\fP field provides a means of preventing PCRE from using up a
1498  vast amount of resources when running patterns that are not going to match,  vast amount of resources when running patterns that are not going to match,
# Line 1516  This limit is of use only if it is set s Line 1528  This limit is of use only if it is set s
1528  Limiting the recursion depth limits the amount of machine stack that can be  Limiting the recursion depth limits the amount of machine stack that can be
1529  used, or, when PCRE has been compiled to use memory on the heap instead of the  used, or, when PCRE has been compiled to use memory on the heap instead of the
1530  stack, the amount of heap memory that can be used. This limit is not relevant,  stack, the amount of heap memory that can be used. This limit is not relevant,
1531  and is ignored, when matching is done using JIT compiled code.  and is ignored, when matching is done using JIT compiled code.
1532  .P  .P
1533  The default value for \fImatch_limit_recursion\fP can be set when PCRE is  The default value for \fImatch_limit_recursion\fP can be set when PCRE is
1534  built; the default default is the same value as the default for  built; the default default is the same value as the default for
# Line 1700  causing performance to suffer, but ensur Line 1712  causing performance to suffer, but ensur
1712  "no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK)  "no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK)
1713  are considered at every possible starting position in the subject string. If  are considered at every possible starting position in the subject string. If
1714  PCRE_NO_START_OPTIMIZE is set at compile time, it cannot be unset at matching  PCRE_NO_START_OPTIMIZE is set at compile time, it cannot be unset at matching
1715  time. The use of PCRE_NO_START_OPTIMIZE disables JIT execution; when it is set,  time. The use of PCRE_NO_START_OPTIMIZE disables JIT execution; when it is set,
1716  matching is always done using interpretively.  matching is always done using interpretively.
1717  .P  .P
1718  Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation.  Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation.
# Line 1734  returned. Line 1746  returned.
1746  .sp  .sp
1747  When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8  When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8
1748  string is automatically checked when \fBpcre_exec()\fP is subsequently called.  string is automatically checked when \fBpcre_exec()\fP is subsequently called.
1749  The value of \fIstartoffset\fP is also checked to ensure that it points to the  The entire string is checked before any other processing takes place. The value
1750  start of a UTF-8 character. There is a discussion about the validity of UTF-8  of \fIstartoffset\fP is also checked to ensure that it points to the start of a
1751  strings in the  UTF-8 character. There is a discussion about the
1752    .\" HTML <a href="pcreunicode.html#utf8strings">
1753    .\" </a>
1754    validity of UTF-8 strings
1755    .\"
1756    in the
1757  .\" HREF  .\" HREF
1758  \fBpcreunicode\fP  \fBpcreunicode\fP
1759  .\"  .\"
# Line 1884  string that it matched that is returned. Line 1901  string that it matched that is returned.
1901  .P  .P
1902  If the vector is too small to hold all the captured substring offsets, it is  If the vector is too small to hold all the captured substring offsets, it is
1903  used as far as possible (up to two-thirds of its length), and the function  used as far as possible (up to two-thirds of its length), and the function
1904  returns a value of zero. If neither the actual string matched not any captured  returns a value of zero. If neither the actual string matched nor any captured
1905  substrings are of interest, \fBpcre_exec()\fP may be called with \fIovector\fP  substrings are of interest, \fBpcre_exec()\fP may be called with \fIovector\fP
1906  passed as NULL and \fIovecsize\fP as zero. However, if the pattern contains  passed as NULL and \fIovecsize\fP as zero. However, if the pattern contains
1907  back references and the \fIovector\fP is not big enough to remember the related  back references and the \fIovector\fP is not big enough to remember the related
# Line 2084  time. Line 2101  time.
2101  .sp  .sp
2102    PCRE_ERROR_JIT_STACKLIMIT (-27)    PCRE_ERROR_JIT_STACKLIMIT (-27)
2103  .sp  .sp
2104  This error is returned when a pattern that was successfully studied using the  This error is returned when a pattern that was successfully studied using a
2105  PCRE_STUDY_JIT_COMPILE option is being matched, but the memory available for  JIT compile option is being matched, but the memory available for the
2106  the just-in-time processing stack is not large enough. See the  just-in-time processing stack is not large enough. See the
2107  .\" HREF  .\" HREF
2108  \fBpcrejit\fP  \fBpcrejit\fP
2109  .\"  .\"
2110  documentation for more details.  documentation for more details.
2111  .sp  .sp
2112    PCRE_ERROR_BADMODE (-28)    PCRE_ERROR_BADMODE        (-28)
2113  .sp  .sp
2114  This error is given if a pattern that was compiled by the 8-bit library is  This error is given if a pattern that was compiled by the 8-bit library is
2115  passed to a 16-bit library function, or vice versa.  passed to a 16-bit library function, or vice versa.
2116  .sp  .sp
2117    PCRE_ERROR_BADENDIANNESS (-29)    PCRE_ERROR_BADENDIANNESS  (-29)
2118  .sp  .sp
2119  This error is given if a pattern that was compiled and saved is reloaded on a  This error is given if a pattern that was compiled and saved is reloaded on a
2120  host with different endianness. The utility function  host with different endianness. The utility function
2121  \fBpcre_pattern_to_host_byte_order()\fP can be used to convert such a pattern  \fBpcre_pattern_to_host_byte_order()\fP can be used to convert such a pattern
2122  so that it runs on the new host.  so that it runs on the new host.
2123  .P  .P
2124  Error numbers -16 to -20 and -22 are not used by \fBpcre_exec()\fP.  Error numbers -16 to -20, -22, and -30 are not used by \fBpcre_exec()\fP.
2125  .  .
2126  .  .
2127  .\" HTML <a name="badutf8reasons"></a>  .\" HTML <a name="badutf8reasons"></a>
# Line 2622  When a recursive subpattern is processed Line 2639  When a recursive subpattern is processed
2639  recursively, using private vectors for \fIovector\fP and \fIworkspace\fP. This  recursively, using private vectors for \fIovector\fP and \fIworkspace\fP. This
2640  error is given if the output vector is not large enough. This should be  error is given if the output vector is not large enough. This should be
2641  extremely rare, as a vector of size 1000 is used.  extremely rare, as a vector of size 1000 is used.
2642    .sp
2643      PCRE_ERROR_DFA_BADRESTART (-30)
2644    .sp
2645    When \fBpcre_dfa_exec()\fP is called with the \fBPCRE_DFA_RESTART\fP option,
2646    some plausibility checks are made on the contents of the workspace, which
2647    should contain data about the previous partial match. If any of these checks
2648    fail, this error is given.
2649  .  .
2650  .  .
2651  .SH "SEE ALSO"  .SH "SEE ALSO"
# Line 2646  Cambridge CB2 3QH, England. Line 2670  Cambridge CB2 3QH, England.
2670  .rs  .rs
2671  .sp  .sp
2672  .nf  .nf
2673  Last updated: 18 February 2012  Last updated: 28 August 2012
2674  Copyright (c) 1997-2012 University of Cambridge.  Copyright (c) 1997-2012 University of Cambridge.
2675  .fi  .fi

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