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revision 930 by ph10, Fri Feb 24 12:05:54 2012 UTC revision 1031 by ph10, Sat Sep 8 15:59:01 2012 UTC
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1  .TH PCREAPI 3  .TH PCREAPI 3 "07 September 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 422  unaligned)". If JIT support is not avail Line 422  unaligned)". If JIT support is not avail
422    PCRE_CONFIG_NEWLINE    PCRE_CONFIG_NEWLINE
423  .sp  .sp
424  The output is an integer whose value specifies the default character sequence  The output is an integer whose value specifies the default character sequence
425  that is recognized as meaning "newline". The four values that are supported  that is recognized as meaning "newline". The values that are supported in
426  are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for ANYCRLF, and -1 for ANY.  ASCII/Unicode environments are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for
427  Though they are derived from ASCII, the same values are returned in EBCDIC  ANYCRLF, and -1 for ANY. In EBCDIC environments, CR, ANYCRLF, and ANY yield the
428  environments. The default should normally correspond to the standard sequence  same values. However, the value for LF is normally 21, though some EBCDIC
429  for your operating system.  environments use 37. The corresponding values for CRLF are 3349 and 3365. The
430    default should normally correspond to the standard sequence for your operating
431    system.
432  .sp  .sp
433    PCRE_CONFIG_BSR    PCRE_CONFIG_BSR
434  .sp  .sp
# Line 642  documentation. Line 644  documentation.
644  .sp  .sp
645    PCRE_EXTENDED    PCRE_EXTENDED
646  .sp  .sp
647  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
648  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
649  include the VT character (code 11). In addition, characters between an  include the VT character (code 11). In addition, characters between an
650  unescaped # outside a character class and the next newline, inclusive, are also  unescaped # outside a character class and the next newline, inclusive, are also
651  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 663  comment is a literal newline sequence in
663  happen to represent a newline do not count.  happen to represent a newline do not count.
664  .P  .P
665  This option makes it possible to include comments inside complicated patterns.  This option makes it possible to include comments inside complicated patterns.
666  Note, however, that this applies only to data characters. Whitespace characters  Note, however, that this applies only to data characters. White space characters
667  may never appear within special character sequences in a pattern, for example  may never appear within special character sequences in a pattern, for example
668  within the sequence (?( that introduces a conditional subpattern.  within the sequence (?( that introduces a conditional subpattern.
669  .sp  .sp
# Line 739  indicated by a single character (CR or L Line 741  indicated by a single character (CR or L
741  PCRE_NEWLINE_CRLF specifies that a newline is indicated by the two-character  PCRE_NEWLINE_CRLF specifies that a newline is indicated by the two-character
742  CRLF sequence. Setting PCRE_NEWLINE_ANYCRLF specifies that any of the three  CRLF sequence. Setting PCRE_NEWLINE_ANYCRLF specifies that any of the three
743  preceding sequences should be recognized. Setting PCRE_NEWLINE_ANY specifies  preceding sequences should be recognized. Setting PCRE_NEWLINE_ANY specifies
744  that any Unicode newline sequence should be recognized. The Unicode newline  that any Unicode newline sequence should be recognized.
745  sequences are the three just mentioned, plus the single characters VT (vertical  .P
746  tab, U+000B), FF (formfeed, U+000C), NEL (next line, U+0085), LS (line  In an ASCII/Unicode environment, the Unicode newline sequences are the three
747  separator, U+2028), and PS (paragraph separator, U+2029). For the 8-bit  just mentioned, plus the single characters VT (vertical tab, U+000B), FF (form
748  library, the last two are recognized only in UTF-8 mode.  feed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
749    (paragraph separator, U+2029). For the 8-bit library, the last two are
750    recognized only in UTF-8 mode.
751    .P
752    When PCRE is compiled to run in an EBCDIC (mainframe) environment, the code for
753    CR is 0x0d, the same as ASCII. However, the character code for LF is normally
754    0x15, though in some EBCDIC environments 0x25 is used. Whichever of these is
755    not LF is made to correspond to Unicode's NEL character. EBCDIC codes are all
756    less than 256. For more details, see the
757    .\" HREF
758    \fBpcrebuild\fP
759    .\"
760    documentation.
761  .P  .P
762  The newline setting in the options word uses three bits that are treated  The newline setting in the options word uses three bits that are treated
763  as a number, giving eight possibilities. Currently only six are used (default  as a number, giving eight possibilities. Currently only six are used (default
# Line 753  PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is Line 767  PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is
767  other combinations may yield unused numbers and cause an error.  other combinations may yield unused numbers and cause an error.
768  .P  .P
769  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
770  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,
771  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
772  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
773  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 940  fallen out of use. To avoid confusion, t
940    72  too many forward references    72  too many forward references
941    73  disallowed Unicode code point (>= 0xd800 && <= 0xdfff)    73  disallowed Unicode code point (>= 0xd800 && <= 0xdfff)
942    74  invalid UTF-16 string (specifically UTF-16)    74  invalid UTF-16 string (specifically UTF-16)
943      75  name is too long in (*MARK), (*PRUNE), (*SKIP), or (*THEN)
944      76  character value in \eu.... sequence is too large
945  .sp  .sp
946  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
947  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 974  below
974  in the section on matching a pattern.  in the section on matching a pattern.
975  .P  .P
976  If studying the pattern does not produce any useful information,  If studying the pattern does not produce any useful information,
977  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program  \fBpcre_study()\fP returns NULL by default. In that circumstance, if the
978  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
979  \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,
980    if \fBpcre_study()\fP is called with the PCRE_STUDY_EXTRA_NEEDED option, it
981    returns a \fBpcre_extra\fP block even if studying did not find any additional
982    information. It may still return NULL, however, if an error occurs in
983    \fBpcre_study()\fP.
984  .P  .P
985  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
986  options:  further options in addition to PCRE_STUDY_EXTRA_NEEDED:
987  .sp  .sp
988    PCRE_STUDY_JIT_COMPILE    PCRE_STUDY_JIT_COMPILE
989    PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE    PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
990    PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE    PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
991  .sp  .sp
992  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
993  pattern is further compiled into machine code that executes much faster than  pattern is further compiled into machine code that executes much faster than
994  the \fBpcre_exec()\fP interpretive matching function. If the just-in-time  the \fBpcre_exec()\fP interpretive matching function. If the just-in-time
995  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
996  \fIoptions\fP argument must be zero.  \fIoptions\fP argument must be zero.
997  .P  .P
998  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 1040  real application there should be tests f
1040  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
1041  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
1042  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
1043  guarantee that no shorter strings match. The value is used by  guarantee that no shorter strings match. The value is used to avoid wasting
1044  \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
1045  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.  
1046  .P  .P
1047  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
1048  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 1254  only if it follows something of variable
1254  /^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
1255  is -1.  is -1.
1256  .sp  .sp
1257      PCRE_INFO_MAXLOOKBEHIND
1258    .sp
1259    Return the number of characters (NB not bytes) in the longest lookbehind
1260    assertion in the pattern. Note that the simple assertions \eb and \eB require a
1261    one-character lookbehind. This information is useful when doing multi-segment
1262    matching using the partial matching facilities.
1263    .sp
1264    PCRE_INFO_MINLENGTH    PCRE_INFO_MINLENGTH
1265  .sp  .sp
1266  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 1516  This limit is of use only if it is set s Line 1542  This limit is of use only if it is set s
1542  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
1543  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
1544  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,
1545  and is ignored, when matching is done using JIT compiled code.  and is ignored, when matching is done using JIT compiled code.
1546  .P  .P
1547  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
1548  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 1726  causing performance to suffer, but ensur
1726  "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)
1727  are considered at every possible starting position in the subject string. If  are considered at every possible starting position in the subject string. If
1728  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
1729  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,
1730  matching is always done using interpretively.  matching is always done using interpretively.
1731  .P  .P
1732  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 1760  returned.
1760  .sp  .sp
1761  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
1762  string is automatically checked when \fBpcre_exec()\fP is subsequently called.  string is automatically checked when \fBpcre_exec()\fP is subsequently called.
1763  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
1764  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
1765  strings in the  UTF-8 character. There is a discussion about the
1766    .\" HTML <a href="pcreunicode.html#utf8strings">
1767    .\" </a>
1768    validity of UTF-8 strings
1769    .\"
1770    in the
1771  .\" HREF  .\" HREF
1772  \fBpcreunicode\fP  \fBpcreunicode\fP
1773  .\"  .\"
# Line 1884  string that it matched that is returned. Line 1915  string that it matched that is returned.
1915  .P  .P
1916  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
1917  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
1918  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
1919  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
1920  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
1921  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 2092  just-in-time processing stack is not lar Line 2123  just-in-time processing stack is not lar
2123  .\"  .\"
2124  documentation for more details.  documentation for more details.
2125  .sp  .sp
2126    PCRE_ERROR_BADMODE (-28)    PCRE_ERROR_BADMODE        (-28)
2127  .sp  .sp
2128  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
2129  passed to a 16-bit library function, or vice versa.  passed to a 16-bit library function, or vice versa.
2130  .sp  .sp
2131    PCRE_ERROR_BADENDIANNESS (-29)    PCRE_ERROR_BADENDIANNESS  (-29)
2132  .sp  .sp
2133  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
2134  host with different endianness. The utility function  host with different endianness. The utility function
2135  \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
2136  so that it runs on the new host.  so that it runs on the new host.
2137  .P  .P
2138  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.
2139  .  .
2140  .  .
2141  .\" HTML <a name="badutf8reasons"></a>  .\" HTML <a name="badutf8reasons"></a>
# Line 2622  When a recursive subpattern is processed Line 2653  When a recursive subpattern is processed
2653  recursively, using private vectors for \fIovector\fP and \fIworkspace\fP. This  recursively, using private vectors for \fIovector\fP and \fIworkspace\fP. This
2654  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
2655  extremely rare, as a vector of size 1000 is used.  extremely rare, as a vector of size 1000 is used.
2656    .sp
2657      PCRE_ERROR_DFA_BADRESTART (-30)
2658    .sp
2659    When \fBpcre_dfa_exec()\fP is called with the \fBPCRE_DFA_RESTART\fP option,
2660    some plausibility checks are made on the contents of the workspace, which
2661    should contain data about the previous partial match. If any of these checks
2662    fail, this error is given.
2663  .  .
2664  .  .
2665  .SH "SEE ALSO"  .SH "SEE ALSO"
# Line 2646  Cambridge CB2 3QH, England. Line 2684  Cambridge CB2 3QH, England.
2684  .rs  .rs
2685  .sp  .sp
2686  .nf  .nf
2687  Last updated: 22 February 2012  Last updated: 07 September 2012
2688  Copyright (c) 1997-2012 University of Cambridge.  Copyright (c) 1997-2012 University of Cambridge.
2689  .fi  .fi

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