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revision 964 by ph10, Fri May 4 13:03:39 2012 UTC revision 1022 by ph10, Tue Aug 28 12:28:15 2012 UTC
# Line 1  Line 1 
1  .TH PCREAPI 3 "04 May 2012" "PCRE 8.31"  .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 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)    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 959  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 1021  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 1240  is -1. Line 1244  is -1.
1244  .sp  .sp
1245  Return the number of characters (NB not bytes) in the longest lookbehind  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  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  one-character lookbehind. This information is useful when doing multi-segment
1248  matching using the partial matching facilities.  matching using the partial matching facilities.
1249  .sp  .sp
1250    PCRE_INFO_MINLENGTH    PCRE_INFO_MINLENGTH
# Line 1524  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 1708  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 2639  extremely rare, as a vector of size 1000 Line 2643  extremely rare, as a vector of size 1000
2643    PCRE_ERROR_DFA_BADRESTART (-30)    PCRE_ERROR_DFA_BADRESTART (-30)
2644  .sp  .sp
2645  When \fBpcre_dfa_exec()\fP is called with the \fBPCRE_DFA_RESTART\fP option,  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  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  should contain data about the previous partial match. If any of these checks
2648  fail, this error is given.  fail, this error is given.
2649  .  .
2650  .  .
2651  .SH "SEE ALSO"  .SH "SEE ALSO"
# Line 2666  Cambridge CB2 3QH, England. Line 2670  Cambridge CB2 3QH, England.
2670  .rs  .rs
2671  .sp  .sp
2672  .nf  .nf
2673  Last updated: 04 May 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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