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revision 454 by ph10, Tue Sep 22 09:42:11 2009 UTC revision 510 by ph10, Sat Mar 27 17:45:29 2010 UTC
# Line 395  avoiding the use of the stack. Line 395  avoiding the use of the stack.
395  Either of the functions \fBpcre_compile()\fP or \fBpcre_compile2()\fP can be  Either of the functions \fBpcre_compile()\fP or \fBpcre_compile2()\fP can be
396  called to compile a pattern into an internal form. The only difference between  called to compile a pattern into an internal form. The only difference between
397  the two interfaces is that \fBpcre_compile2()\fP has an additional argument,  the two interfaces is that \fBpcre_compile2()\fP has an additional argument,
398  \fIerrorcodeptr\fP, via which a numerical error code can be returned.  \fIerrorcodeptr\fP, via which a numerical error code can be returned. To avoid
399    too much repetition, we refer just to \fBpcre_compile()\fP below, but the
400    information applies equally to \fBpcre_compile2()\fP.
401  .P  .P
402  The pattern is a C string terminated by a binary zero, and is passed in the  The pattern is a C string terminated by a binary zero, and is passed in the
403  \fIpattern\fP argument. A pointer to a single block of memory that is obtained  \fIpattern\fP argument. A pointer to a single block of memory that is obtained
# Line 412  argument, which is an address (see below Line 414  argument, which is an address (see below
414  The \fIoptions\fP argument contains various bit settings that affect the  The \fIoptions\fP argument contains various bit settings that affect the
415  compilation. It should be zero if no options are required. The available  compilation. It should be zero if no options are required. The available
416  options are described below. Some of them (in particular, those that are  options are described below. Some of them (in particular, those that are
417  compatible with Perl, but also some others) can also be set and unset from  compatible with Perl, but some others as well) can also be set and unset from
418  within the pattern (see the detailed description in the  within the pattern (see the detailed description in the
419  .\" HREF  .\" HREF
420  \fBpcrepattern\fP  \fBpcrepattern\fP
421  .\"  .\"
422  documentation). For those options that can be different in different parts of  documentation). For those options that can be different in different parts of
423  the pattern, the contents of the \fIoptions\fP argument specifies their initial  the pattern, the contents of the \fIoptions\fP argument specifies their
424  settings at the start of compilation and execution. The PCRE_ANCHORED and  settings at the start of compilation and execution. The PCRE_ANCHORED,
425  PCRE_NEWLINE_\fIxxx\fP options can be set at the time of matching as well as at  PCRE_BSR_\fIxxx\fP, and PCRE_NEWLINE_\fIxxx\fP options can be set at the time
426  compile time.  of matching as well as at compile time.
427  .P  .P
428  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
429  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns  Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns
430  NULL, and sets the variable pointed to by \fIerrptr\fP to point to a textual  NULL, and sets the variable pointed to by \fIerrptr\fP to point to a textual
431  error message. This is a static string that is part of the library. You must  error message. This is a static string that is part of the library. You must
432  not try to free it. The byte offset from the start of the pattern to the  not try to free it. The byte offset from the start of the pattern to the
433  character that was being processes when the error was discovered is placed in  character that was being processed when the error was discovered is placed in
434  the variable pointed to by \fIerroffset\fP, which must not be NULL. If it is,  the variable pointed to by \fIerroffset\fP, which must not be NULL. If it is,
435  an immediate error is given. Some errors are not detected until checks are  an immediate error is given. Some errors are not detected until checks are
436  carried out when the whole pattern has been scanned; in this case the offset is  carried out when the whole pattern has been scanned; in this case the offset is
# Line 745  out of use. To avoid confusion, they hav Line 747  out of use. To avoid confusion, they hav
747    57  \eg is not followed by a braced, angle-bracketed, or quoted    57  \eg is not followed by a braced, angle-bracketed, or quoted
748          name/number or by a plain number          name/number or by a plain number
749    58  a numbered reference must not be zero    58  a numbered reference must not be zero
750    59  (*VERB) with an argument is not supported    59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
751    60  (*VERB) not recognized    60  (*VERB) not recognized
752    61  number is too big    61  number is too big
753    62  subpattern name expected    62  subpattern name expected
754    63  digit expected after (?+    63  digit expected after (?+
755    64  ] is an invalid data character in JavaScript compatibility mode    64  ] is an invalid data character in JavaScript compatibility mode
756      65  different names for subpatterns of the same number are not allowed
757      66  (*MARK) must have an argument
758  .sp  .sp
759  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
760  be used if the limits were changed when PCRE was built.  be used if the limits were changed when PCRE was built.
# Line 772  help speed up matching, \fBpcre_study()\ Line 776  help speed up matching, \fBpcre_study()\
776  results of the study.  results of the study.
777  .P  .P
778  The returned value from \fBpcre_study()\fP can be passed directly to  The returned value from \fBpcre_study()\fP can be passed directly to
779  \fBpcre_exec()\fP. However, a \fBpcre_extra\fP block also contains other  \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP. However, a \fBpcre_extra\fP block
780  fields that can be set by the caller before the block is passed; these are  also contains other fields that can be set by the caller before the block is
781  described  passed; these are described
782  .\" HTML <a href="#extradata">  .\" HTML <a href="#extradata">
783  .\" </a>  .\" </a>
784  below  below
785  .\"  .\"
786  in the section on matching a pattern.  in the section on matching a pattern.
787  .P  .P
788  If studying the pattern does not produce any additional information  If studying the pattern does not produce any useful information,
789  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program  \fBpcre_study()\fP returns NULL. In that circumstance, if the calling program
790  wants to pass any of the other fields to \fBpcre_exec()\fP, it must set up its  wants to pass any of the other fields to \fBpcre_exec()\fP or
791  own \fBpcre_extra\fP block.  \fBpcre_dfa_exec()\fP, it must set up its own \fBpcre_extra\fP block.
792  .P  .P
793  The second argument of \fBpcre_study()\fP contains option bits. At present, no  The second argument of \fBpcre_study()\fP contains option bits. At present, no
794  options are defined, and this argument should always be zero.  options are defined, and this argument should always be zero.
# Line 804  This is a typical call to \fBpcre_study\ Line 808  This is a typical call to \fBpcre_study\
808      0,              /* no options exist */      0,              /* no options exist */
809      &error);        /* set to NULL or points to a message */      &error);        /* set to NULL or points to a message */
810  .sp  .sp
811  At present, studying a pattern is useful only for non-anchored patterns that do  Studying a pattern does two things: first, a lower bound for the length of
812  not have a single fixed starting character. A bitmap of possible starting  subject string that is needed to match the pattern is computed. This does not
813  bytes is created.  mean that there are any strings of that length that match, but it does
814    guarantee that no shorter strings match. The value is used by
815    \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP to avoid wasting time by trying to
816    match strings that are shorter than the lower bound. You can find out the value
817    in a calling program via the \fBpcre_fullinfo()\fP function.
818    .P
819    Studying a pattern is also useful for non-anchored patterns that do not have a
820    single fixed starting character. A bitmap of possible starting bytes is
821    created. This speeds up finding a position in the subject at which to start
822    matching.
823  .  .
824  .  .
825  .\" HTML <a name="localesupport"></a>  .\" HTML <a name="localesupport"></a>
# Line 971  follows something of variable length. Fo Line 984  follows something of variable length. Fo
984  /^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
985  is -1.  is -1.
986  .sp  .sp
987      PCRE_INFO_MINLENGTH
988    .sp
989    If the pattern was studied and a minimum length for matching subject strings
990    was computed, its value is returned. Otherwise the returned value is -1. The
991    value is a number of characters, not bytes (this may be relevant in UTF-8
992    mode). The fourth argument should point to an \fBint\fP variable. A
993    non-negative value is a lower bound to the length of any matching string. There
994    may not be any strings of that length that do actually match, but every string
995    that does match is at least that long.
996    .sp
997    PCRE_INFO_NAMECOUNT    PCRE_INFO_NAMECOUNT
998    PCRE_INFO_NAMEENTRYSIZE    PCRE_INFO_NAMEENTRYSIZE
999    PCRE_INFO_NAMETABLE    PCRE_INFO_NAMETABLE
# Line 991  entry; both of these return an \fBint\fP Line 1014  entry; both of these return an \fBint\fP
1014  length of the longest name. PCRE_INFO_NAMETABLE returns a pointer to the first  length of the longest name. PCRE_INFO_NAMETABLE returns a pointer to the first
1015  entry of the table (a pointer to \fBchar\fP). The first two bytes of each entry  entry of the table (a pointer to \fBchar\fP). The first two bytes of each entry
1016  are the number of the capturing parenthesis, most significant byte first. The  are the number of the capturing parenthesis, most significant byte first. The
1017  rest of the entry is the corresponding name, zero terminated. The names are in  rest of the entry is the corresponding name, zero terminated.
1018  alphabetical order. When PCRE_DUPNAMES is set, duplicate names are in order of  .P
1019  their parentheses numbers. For example, consider the following pattern (assume  The names are in alphabetical order. Duplicate names may appear if (?| is used
1020  PCRE_EXTENDED is set, so white space - including newlines - is ignored):  to create multiple groups with the same number, as described in the
1021    .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
1022    .\" </a>
1023    section on duplicate subpattern numbers
1024    .\"
1025    in the
1026    .\" HREF
1027    \fBpcrepattern\fP
1028    .\"
1029    page. Duplicate names for subpatterns with different numbers are permitted only
1030    if PCRE_DUPNAMES is set. In all cases of duplicate names, they appear in the
1031    table in the order in which they were found in the pattern. In the absence of
1032    (?| this is the order of increasing number; when (?| is used this is not
1033    necessarily the case because later subpatterns may have lower numbers.
1034    .P
1035    As a simple example of the name/number table, consider the following pattern
1036    (assume PCRE_EXTENDED is set, so white space - including newlines - is
1037    ignored):
1038  .sp  .sp
1039  .\" JOIN  .\" JOIN
1040    (?<date> (?<year>(\ed\ed)?\ed\ed) -    (?<date> (?<year>(\ed\ed)?\ed\ed) -
# Line 1059  variable. Line 1099  variable.
1099  Return the size of the data block pointed to by the \fIstudy_data\fP field in  Return the size of the data block pointed to by the \fIstudy_data\fP field in
1100  a \fBpcre_extra\fP block. That is, it is the value that was passed to  a \fBpcre_extra\fP block. That is, it is the value that was passed to
1101  \fBpcre_malloc()\fP when PCRE was getting memory into which to place the data  \fBpcre_malloc()\fP when PCRE was getting memory into which to place the data
1102  created by \fBpcre_study()\fP. The fourth argument should point to a  created by \fBpcre_study()\fP. If \fBpcre_extra\fP is NULL, or there is no
1103    study data, zero is returned. The fourth argument should point to a
1104  \fBsize_t\fP variable.  \fBsize_t\fP variable.
1105  .  .
1106  .  .
# Line 1121  is different. (This seems a highly unlik Line 1162  is different. (This seems a highly unlik
1162  .P  .P
1163  The function \fBpcre_exec()\fP is called to match a subject string against a  The function \fBpcre_exec()\fP is called to match a subject string against a
1164  compiled pattern, which is passed in the \fIcode\fP argument. If the  compiled pattern, which is passed in the \fIcode\fP argument. If the
1165  pattern has been studied, the result of the study should be passed in the  pattern was studied, the result of the study should be passed in the
1166  \fIextra\fP argument. This function is the main matching facility of the  \fIextra\fP argument. This function is the main matching facility of the
1167  library, and it operates in a Perl-like manner. For specialist use there is  library, and it operates in a Perl-like manner. For specialist use there is
1168  also an alternative matching function, which is described  also an alternative matching function, which is described
# Line 1171  fields (not necessarily in this order): Line 1212  fields (not necessarily in this order):
1212    unsigned long int \fImatch_limit_recursion\fP;    unsigned long int \fImatch_limit_recursion\fP;
1213    void *\fIcallout_data\fP;    void *\fIcallout_data\fP;
1214    const unsigned char *\fItables\fP;    const unsigned char *\fItables\fP;
1215      unsigned char **\fImark\fP;
1216  .sp  .sp
1217  The \fIflags\fP field is a bitmap that specifies which of the other fields  The \fIflags\fP field is a bitmap that specifies which of the other fields
1218  are set. The flag bits are:  are set. The flag bits are:
# Line 1180  are set. The flag bits are: Line 1222  are set. The flag bits are:
1222    PCRE_EXTRA_MATCH_LIMIT_RECURSION    PCRE_EXTRA_MATCH_LIMIT_RECURSION
1223    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1224    PCRE_EXTRA_TABLES    PCRE_EXTRA_TABLES
1225      PCRE_EXTRA_MARK
1226  .sp  .sp
1227  Other flag bits should be set to zero. The \fIstudy_data\fP field is set in the  Other flag bits should be set to zero. The \fIstudy_data\fP field is set in the
1228  \fBpcre_extra\fP block that is returned by \fBpcre_study()\fP, together with  \fBpcre_extra\fP block that is returned by \fBpcre_study()\fP, together with
# Line 1189  the block by setting the other fields an Line 1232  the block by setting the other fields an
1232  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
1233  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,
1234  but which have a very large number of possibilities in their search trees. The  but which have a very large number of possibilities in their search trees. The
1235  classic example is the use of nested unlimited repeats.  classic example is a pattern that uses nested unlimited repeats.
1236  .P  .P
1237  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly
1238  (sometimes recursively). The limit set by \fImatch_limit\fP is imposed on the  (sometimes recursively). The limit set by \fImatch_limit\fP is imposed on the
# Line 1242  called. See the Line 1285  called. See the
1285  \fBpcreprecompile\fP  \fBpcreprecompile\fP
1286  .\"  .\"
1287  documentation for a discussion of saving compiled patterns for later use.  documentation for a discussion of saving compiled patterns for later use.
1288    .P
1289    If PCRE_EXTRA_MARK is set in the \fIflags\fP field, the \fImark\fP field must
1290    be set to point to a \fBchar *\fP variable. If the pattern contains any
1291    backtracking control verbs such as (*MARK:NAME), and the execution ends up with
1292    a name to pass back, a pointer to the name string (zero terminated) is placed
1293    in the variable pointed to by the \fImark\fP field. The names are within the
1294    compiled pattern; if you wish to retain such a name you must copy it before
1295    freeing the memory of a compiled pattern. If there is no name to pass back, the
1296    variable pointed to by the \fImark\fP field set to NULL. For details of the
1297    backtracking control verbs, see the section entitled
1298    .\" HTML <a href="pcrepattern#backtrackcontrol">
1299    .\" </a>
1300    "Backtracking control"
1301    .\"
1302    in the
1303    .\" HREF
1304    \fBpcrepattern\fP
1305    .\"
1306    documentation.
1307    .
1308  .  .
1309  .\" HTML <a name="execoptions"></a>  .\" HTML <a name="execoptions"></a>
1310  .SS "Option bits for \fBpcre_exec()\fP"  .SS "Option bits for \fBpcre_exec()\fP"
# Line 1332  valid, so PCRE searches further into the Line 1395  valid, so PCRE searches further into the
1395  .sp  .sp
1396    PCRE_NOTEMPTY_ATSTART    PCRE_NOTEMPTY_ATSTART
1397  .sp  .sp
1398  This is like PCRE_NOTEMPTY, except that an empty string match that is not at  This is like PCRE_NOTEMPTY, except that an empty string match that is not at
1399  the start of the subject is permitted. If the pattern is anchored, such a match  the start of the subject is permitted. If the pattern is anchored, such a match
1400  can occur only if the pattern contains \eK.  can occur only if the pattern contains \eK.
1401  .P  .P
# Line 1388  PCRE_NO_UTF8_CHECK is set, the effect of Line 1451  PCRE_NO_UTF8_CHECK is set, the effect of
1451  subject, or a value of \fIstartoffset\fP that does not point to the start of a  subject, or a value of \fIstartoffset\fP that does not point to the start of a
1452  UTF-8 character, is undefined. Your program may crash.  UTF-8 character, is undefined. Your program may crash.
1453  .sp  .sp
1454    PCRE_PARTIAL_HARD    PCRE_PARTIAL_HARD
1455    PCRE_PARTIAL_SOFT    PCRE_PARTIAL_SOFT
1456  .sp  .sp
1457  These options turn on the partial matching feature. For backwards  These options turn on the partial matching feature. For backwards
# Line 1488  the \fIovector\fP is not big enough to r Line 1551  the \fIovector\fP is not big enough to r
1551  has to get additional memory for use during matching. Thus it is usually  has to get additional memory for use during matching. Thus it is usually
1552  advisable to supply an \fIovector\fP.  advisable to supply an \fIovector\fP.
1553  .P  .P
1554  The \fBpcre_info()\fP function can be used to find out how many capturing  The \fBpcre_fullinfo()\fP function can be used to find out how many capturing
1555  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
1556  \fIovector\fP that will allow for \fIn\fP captured substrings, in addition to  \fIovector\fP that will allow for \fIn\fP captured substrings, in addition to
1557  the offsets of the substring matched by the whole pattern, is (\fIn\fP+1)*3.  the offsets of the substring matched by the whole pattern, is (\fIn\fP+1)*3.
# Line 1595  documentation for details of partial mat Line 1658  documentation for details of partial mat
1658  .sp  .sp
1659  This code is no longer in use. It was formerly returned when the PCRE_PARTIAL  This code is no longer in use. It was formerly returned when the PCRE_PARTIAL
1660  option was used with a compiled pattern containing items that were not  option was used with a compiled pattern containing items that were not
1661  supported for partial matching. From release 8.00 onwards, there are no  supported for partial matching. From release 8.00 onwards, there are no
1662  restrictions on partial matching.  restrictions on partial matching.
1663  .sp  .sp
1664    PCRE_ERROR_INTERNAL       (-14)    PCRE_ERROR_INTERNAL       (-14)
# Line 1767  then call \fBpcre_copy_substring()\fP or Line 1830  then call \fBpcre_copy_substring()\fP or
1830  appropriate. \fBNOTE:\fP If PCRE_DUPNAMES is set and there are duplicate names,  appropriate. \fBNOTE:\fP If PCRE_DUPNAMES is set and there are duplicate names,
1831  the behaviour may not be what you want (see the next section).  the behaviour may not be what you want (see the next section).
1832  .P  .P
1833  \fBWarning:\fP If the pattern uses the "(?|" feature to set up multiple  \fBWarning:\fP If the pattern uses the (?| feature to set up multiple
1834  subpatterns with the same number, you cannot use names to distinguish them,  subpatterns with the same number, as described in the
1835  because names are not included in the compiled code. The matching process uses  .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
1836  only numbers.  .\" </a>
1837    section on duplicate subpattern numbers
1838    .\"
1839    in the
1840    .\" HREF
1841    \fBpcrepattern\fP
1842    .\"
1843    page, you cannot use names to distinguish the different subpatterns, because
1844    names are not included in the compiled code. The matching process uses only
1845    numbers. For this reason, the use of different names for subpatterns of the
1846    same number causes an error at compile time.
1847  .  .
1848  .SH "DUPLICATE SUBPATTERN NAMES"  .SH "DUPLICATE SUBPATTERN NAMES"
1849  .rs  .rs
# Line 1780  only numbers. Line 1853  only numbers.
1853  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);  .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);
1854  .PP  .PP
1855  When a pattern is compiled with the PCRE_DUPNAMES option, names for subpatterns  When a pattern is compiled with the PCRE_DUPNAMES option, names for subpatterns
1856  are not required to be unique. Normally, patterns with duplicate names are such  are not required to be unique. (Duplicate names are always allowed for
1857  that in any one match, only one of the named subpatterns participates. An  subpatterns with the same number, created by using the (?| feature. Indeed, if
1858  example is shown in the  such subpatterns are named, they are required to use the same names.)
1859    .P
1860    Normally, patterns with duplicate names are such that in any one match, only
1861    one of the named subpatterns participates. An example is shown in the
1862  .\" HREF  .\" HREF
1863  \fBpcrepattern\fP  \fBpcrepattern\fP
1864  .\"  .\"
# Line 1846  a compiled pattern, using a matching alg Line 1922  a compiled pattern, using a matching alg
1922  just once, and does not backtrack. This has different characteristics to the  just once, and does not backtrack. This has different characteristics to the
1923  normal algorithm, and is not compatible with Perl. Some of the features of PCRE  normal algorithm, and is not compatible with Perl. Some of the features of PCRE
1924  patterns are not supported. Nevertheless, there are times when this kind of  patterns are not supported. Nevertheless, there are times when this kind of
1925  matching can be useful. For a discussion of the two matching algorithms, and a  matching can be useful. For a discussion of the two matching algorithms, and a
1926  list of features that \fBpcre_dfa_exec()\fP does not support, see the  list of features that \fBpcre_dfa_exec()\fP does not support, see the
1927  .\" HREF  .\" HREF
1928  \fBpcrematching\fP  \fBpcrematching\fP
# Line 1892  and PCRE_DFA_RESTART. All but the last f Line 1968  and PCRE_DFA_RESTART. All but the last f
1968  for \fBpcre_exec()\fP, so their description is not repeated here.  for \fBpcre_exec()\fP, so their description is not repeated here.
1969  .sp  .sp
1970    PCRE_PARTIAL_HARD    PCRE_PARTIAL_HARD
1971    PCRE_PARTIAL_SOFT    PCRE_PARTIAL_SOFT
1972  .sp  .sp
1973  These have the same general effect as they do for \fBpcre_exec()\fP, but the  These have the same general effect as they do for \fBpcre_exec()\fP, but the
1974  details are slightly different. When PCRE_PARTIAL_HARD is set for  details are slightly different. When PCRE_PARTIAL_HARD is set for
# Line 2023  Cambridge CB2 3QH, England. Line 2099  Cambridge CB2 3QH, England.
2099  .rs  .rs
2100  .sp  .sp
2101  .nf  .nf
2102  Last updated: 22 September 2009  Last updated: 26 March 2010
2103  Copyright (c) 1997-2009 University of Cambridge.  Copyright (c) 1997-2010 University of Cambridge.
2104  .fi  .fi

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