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revision 656 by ph10, Sat Aug 13 12:27:51 2011 UTC revision 707 by ph10, Fri Sep 23 10:32:53 2011 UTC
# Line 1  Line 1 
1  .TH PCREAPI 3  .TH PCREAPI 3
2  .SH NAME  .SH NAME
3  PCRE - Perl-compatible regular expressions  PCRE - Perl-compatible regular expressions
4  .SH "PCRE NATIVE API"  .SH "PCRE NATIVE API BASIC FUNCTIONS"
5  .rs  .rs
6  .sp  .sp
7  .B #include <pcre.h>  .B #include <pcre.h>
# Line 25  PCRE - Perl-compatible regular expressio Line 25  PCRE - Perl-compatible regular expressio
25  .ti +5n  .ti +5n
26  .B const char **\fIerrptr\fP);  .B const char **\fIerrptr\fP);
27  .PP  .PP
28    .B void pcre_free_study(pcre_extra *\fIextra\fP);
29    .PP
30  .B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"  .B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
31  .ti +5n  .ti +5n
32  .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,  .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
33  .ti +5n  .ti +5n
34  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);  .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);
35    .
36    .
37    .SH "PCRE NATIVE API AUXILIARY FUNCTIONS"
38    .rs
39    .sp
40    .B pcre_jit_stack *pcre_jit_stack_alloc(int \fIstartsize\fP, int \fImaxsize\fP);
41    .PP
42    .B void pcre_jit_stack_free(pcre_jit_stack *\fIstack\fP);
43    .PP
44    .B void pcre_assign_jit_stack(pcre_extra *\fIextra\fP,
45    .ti +5n
46    .B pcre_jit_callback \fIcallback\fP, void *\fIdata\fP);
47  .PP  .PP
48  .B int pcre_dfa_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"  .B int pcre_dfa_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
49  .ti +5n  .ti +5n
# Line 97  PCRE - Perl-compatible regular expressio Line 111  PCRE - Perl-compatible regular expressio
111  .B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);  .B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);
112  .PP  .PP
113  .B char *pcre_version(void);  .B char *pcre_version(void);
114  .PP  .
115    .
116    .SH "PCRE NATIVE API INDIRECTED FUNCTIONS"
117    .rs
118    .sp
119  .B void *(*pcre_malloc)(size_t);  .B void *(*pcre_malloc)(size_t);
120  .PP  .PP
121  .B void (*pcre_free)(void *);  .B void (*pcre_free)(void *);
# Line 114  PCRE - Perl-compatible regular expressio Line 132  PCRE - Perl-compatible regular expressio
132  .sp  .sp
133  PCRE has its own native API, which is described in this document. There are  PCRE has its own native API, which is described in this document. There are
134  also some wrapper functions that correspond to the POSIX regular expression  also some wrapper functions that correspond to the POSIX regular expression
135  API. These are described in the  API, but they do not give access to all the functionality. They are described
136    in the
137  .\" HREF  .\" HREF
138  \fBpcreposix\fP  \fBpcreposix\fP
139  .\"  .\"
140  documentation. Both of these APIs define a set of C function calls. A C++  documentation. Both of these APIs define a set of C function calls. A C++
141  wrapper is distributed with PCRE. It is documented in the  wrapper is also distributed with PCRE. It is documented in the
142  .\" HREF  .\" HREF
143  \fBpcrecpp\fP  \fBpcrecpp\fP
144  .\"  .\"
# Line 152  documentation, and the Line 171  documentation, and the
171  .\"  .\"
172  documentation describes how to compile and run it.  documentation describes how to compile and run it.
173  .P  .P
174    Just-in-time compiler support is an optional feature of PCRE that can be built
175    in appropriate hardware environments. It greatly speeds up the matching
176    performance of many patterns. Simple programs can easily request that it be
177    used if available, by setting an option that is ignored when it is not
178    relevant. More complicated programs might need to make use of the functions
179    \fBpcre_jit_stack_alloc()\fP, \fBpcre_jit_stack_free()\fP, and
180    \fBpcre_assign_jit_stack()\fP in order to control the JIT code's memory usage.
181    These functions are discussed in the
182    .\" HREF
183    \fBpcrejit\fP
184    .\"
185    documentation.
186    .P
187  A second matching function, \fBpcre_dfa_exec()\fP, which is not  A second matching function, \fBpcre_dfa_exec()\fP, which is not
188  Perl-compatible, is also provided. This uses a different algorithm for the  Perl-compatible, is also provided. This uses a different algorithm for the
189  matching. The alternative algorithm finds all possible matches (at a given  matching. The alternative algorithm finds all possible matches (at a given
# Line 282  callout function pointed to by \fBpcre_c Line 314  callout function pointed to by \fBpcre_c
314  .P  .P
315  The compiled form of a regular expression is not altered during matching, so  The compiled form of a regular expression is not altered during matching, so
316  the same compiled pattern can safely be used by several threads at once.  the same compiled pattern can safely be used by several threads at once.
317    .P
318    If the just-in-time optimization feature is being used, it needs separate
319    memory stack areas for each thread. See the
320    .\" HREF
321    \fBpcrejit\fP
322    .\"
323    documentation for more details.
324  .  .
325  .  .
326  .SH "SAVING PRECOMPILED PATTERNS FOR LATER USE"  .SH "SAVING PRECOMPILED PATTERNS FOR LATER USE"
# Line 324  otherwise it is set to zero. Line 363  otherwise it is set to zero.
363  The output is an integer that is set to one if support for Unicode character  The output is an integer that is set to one if support for Unicode character
364  properties is available; otherwise it is set to zero.  properties is available; otherwise it is set to zero.
365  .sp  .sp
366      PCRE_CONFIG_JIT
367    .sp
368    The output is an integer that is set to one if support for just-in-time
369    compiling is available; otherwise it is set to zero.
370    .sp
371    PCRE_CONFIG_NEWLINE    PCRE_CONFIG_NEWLINE
372  .sp  .sp
373  The output is an integer whose value specifies the default character sequence  The output is an integer whose value specifies the default character sequence
# Line 701  of UTF-8 characters instead of single-by Line 745  of UTF-8 characters instead of single-by
745  available only when PCRE is built to include UTF-8 support. If not, the use  available only when PCRE is built to include UTF-8 support. If not, the use
746  of this option provokes an error. Details of how this option changes the  of this option provokes an error. Details of how this option changes the
747  behaviour of PCRE are given in the  behaviour of PCRE are given in the
 .\" HTML <a href="pcre.html#utf8support">  
 .\" </a>  
 section on UTF-8 support  
 .\"  
 in the main  
748  .\" HREF  .\" HREF
749  \fBpcre\fP  \fBpcreunicode\fP
750  .\"  .\"
751  page.  page.
752  .sp  .sp
# Line 812  out of use. To avoid confusion, they hav Line 851  out of use. To avoid confusion, they hav
851    66  (*MARK) must have an argument    66  (*MARK) must have an argument
852    67  this version of PCRE is not compiled with PCRE_UCP support    67  this version of PCRE is not compiled with PCRE_UCP support
853    68  \ec must be followed by an ASCII character    68  \ec must be followed by an ASCII character
854    69  \ek is not followed by a braced, angle-bracketed, or quoted name    69  \ek is not followed by a braced, angle-bracketed, or quoted name
855  .sp  .sp
856  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
857  be used if the limits were changed when PCRE was built.  be used if the limits were changed when PCRE was built.
# Line 849  If studying the pattern does not produce Line 888  If studying the pattern does not produce
888  wants to pass any of the other fields to \fBpcre_exec()\fP or  wants to pass any of the other fields to \fBpcre_exec()\fP or
889  \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.
890  .P  .P
891  The second argument of \fBpcre_study()\fP contains option bits. At present, no  The second argument of \fBpcre_study()\fP contains option bits. There is only
892  options are defined, and this argument should always be zero.  one option: PCRE_STUDY_JIT_COMPILE. If this is set, and the just-in-time
893    compiler is available, the pattern is further compiled into machine code that
894    executes much faster than the \fBpcre_exec()\fP matching function. If
895    the just-in-time compiler is not available, this option is ignored. All other
896    bits in the \fIoptions\fP argument must be zero.
897    .P
898    JIT compilation is a heavyweight optimization. It can take some time for
899    patterns to be analyzed, and for one-off matches and simple patterns the
900    benefit of faster execution might be offset by a much slower study time.
901    Not all patterns can be optimized by the JIT compiler. For those that cannot be
902    handled, matching automatically falls back to the \fBpcre_exec()\fP
903    interpreter. For more details, see the
904    .\" HREF
905    \fBpcrejit\fP
906    .\"
907    documentation.
908  .P  .P
909  The third argument for \fBpcre_study()\fP is a pointer for an error message. If  The third argument for \fBpcre_study()\fP is a pointer for an error message. If
910  studying succeeds (even if no data is returned), the variable it points to is  studying succeeds (even if no data is returned), the variable it points to is
# Line 859  static string that is part of the librar Line 913  static string that is part of the librar
913  should test the error pointer for NULL after calling \fBpcre_study()\fP, to be  should test the error pointer for NULL after calling \fBpcre_study()\fP, to be
914  sure that it has run successfully.  sure that it has run successfully.
915  .P  .P
916  This is a typical call to \fBpcre_study\fP():  When you are finished with a pattern, you can free the memory used for the
917    study data by calling \fBpcre_free_study()\fP. This function was added to the
918    API for release 8.20. For earlier versions, the memory could be freed with
919    \fBpcre_free()\fP, just like the pattern itself. This will still work in cases
920    where PCRE_STUDY_JIT_COMPILE is not used, but it is advisable to change to the
921    new function when convenient.
922    .P
923    This is a typical way in which \fBpcre_study\fP() is used (except that in a
924    real application there should be tests for errors):
925  .sp  .sp
926    pcre_extra *pe;    int rc;
927    pe = pcre_study(    pcre *re;
928      pcre_extra *sd;
929      re = pcre_compile("pattern", 0, &error, &erroroffset, NULL);
930      sd = pcre_study(
931      re,             /* result of pcre_compile() */      re,             /* result of pcre_compile() */
932      0,              /* no options exist */      0,              /* no options */
933      &error);        /* set to NULL or points to a message */      &error);        /* set to NULL or points to a message */
934      rc = pcre_exec(   /* see below for details of pcre_exec() options */
935        re, sd, "subject", 7, 0, 0, ovector, 30);
936      ...
937      pcre_free_study(sd);
938      pcre_free(re);
939  .sp  .sp
940  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
941  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
# Line 880  single fixed starting character. A bitma Line 950  single fixed starting character. A bitma
950  created. This speeds up finding a position in the subject at which to start  created. This speeds up finding a position in the subject at which to start
951  matching.  matching.
952  .P  .P
953  The two optimizations just described can be disabled by setting the  These two optimizations apply to both \fBpcre_exec()\fP and
954  PCRE_NO_START_OPTIMIZE option when calling \fBpcre_exec()\fP or  \fBpcre_dfa_exec()\fP. However, they are not used by \fBpcre_exec()\fP if
955    \fBpcre_study()\fP is called with the PCRE_STUDY_JIT_COMPILE option, and
956    just-in-time compiling is successful. The optimizations can be disabled by
957    setting the PCRE_NO_START_OPTIMIZE option when calling \fBpcre_exec()\fP or
958  \fBpcre_dfa_exec()\fP. You might want to do this if your pattern contains  \fBpcre_dfa_exec()\fP. You might want to do this if your pattern contains
959  callouts or (*MARK), and you want to make use of these facilities in cases  callouts or (*MARK) (which cannot be handled by the JIT compiler), and you want
960  where matching fails. See the discussion of PCRE_NO_START_OPTIMIZE  to make use of these facilities in cases where matching fails. See the
961    discussion of PCRE_NO_START_OPTIMIZE
962  .\" HTML <a href="#execoptions">  .\" HTML <a href="#execoptions">
963  .\" </a>  .\" </a>
964  below.  below.
# Line 981  check against passing an arbitrary memor Line 1055  check against passing an arbitrary memor
1055    size_t length;    size_t length;
1056    rc = pcre_fullinfo(    rc = pcre_fullinfo(
1057      re,               /* result of pcre_compile() */      re,               /* result of pcre_compile() */
1058      pe,               /* result of pcre_study(), or NULL */      sd,               /* result of pcre_study(), or NULL */
1059      PCRE_INFO_SIZE,   /* what is required */      PCRE_INFO_SIZE,   /* what is required */
1060      &length);         /* where to put the data */      &length);         /* where to put the data */
1061  .sp  .sp
# Line 1046  Return 1 if the (?J) or (?-J) option set Line 1120  Return 1 if the (?J) or (?-J) option set
1120  0. The fourth argument should point to an \fBint\fP variable. (?J) and  0. The fourth argument should point to an \fBint\fP variable. (?J) and
1121  (?-J) set and unset the local PCRE_DUPNAMES option, respectively.  (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
1122  .sp  .sp
1123      PCRE_INFO_JIT
1124    .sp
1125    Return 1 if the pattern was studied with the PCRE_STUDY_JIT_COMPILE option, and
1126    just-in-time compiling was successful. The fourth argument should point to an
1127    \fBint\fP variable. A return value of 0 means that JIT support is not available
1128    in this version of PCRE, or that the pattern was not studied with the
1129    PCRE_STUDY_JIT_COMPILE option, or that the JIT compiler could not handle this
1130    particular pattern. See the
1131    .\" HREF
1132    \fBpcrejit\fP
1133    .\"
1134    documentation for details of what can and cannot be handled.
1135    .sp
1136    PCRE_INFO_LASTLITERAL    PCRE_INFO_LASTLITERAL
1137  .sp  .sp
1138  Return the value of the rightmost literal byte that must exist in any matched  Return the value of the rightmost literal byte that must exist in any matched
# Line 1175  The \fIstudy_data\fP field is set by \fB Line 1262  The \fIstudy_data\fP field is set by \fB
1262  that will speed up matching (see the section entitled  that will speed up matching (see the section entitled
1263  .\" HTML <a href="#studyingapattern">  .\" HTML <a href="#studyingapattern">
1264  .\" </a>  .\" </a>
1265  "Studying a pattern"  "Studying a pattern"
1266  .\"  .\"
1267  above). The format of the \fIstudy_data\fP block is private, but its length  above). The format of the \fIstudy_data\fP block is private, but its length
1268  is made available via this option so that it can be saved and restored (see the  is made available via this option so that it can be saved and restored (see the
# Line 1244  is different. (This seems a highly unlik Line 1331  is different. (This seems a highly unlik
1331  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
1332  compiled pattern, which is passed in the \fIcode\fP argument. If the  compiled pattern, which is passed in the \fIcode\fP argument. If the
1333  pattern was studied, the result of the study should be passed in the  pattern was studied, the result of the study should be passed in the
1334  \fIextra\fP argument. This function is the main matching facility of the  \fIextra\fP argument. You can call \fBpcre_exec()\fP with the same \fIcode\fP
1335  library, and it operates in a Perl-like manner. For specialist use there is  and \fIextra\fP arguments as many times as you like, in order to match
1336  also an alternative matching function, which is described  different subject strings with the same pattern.
1337    .P
1338    This function is the main matching facility of the library, and it operates in
1339    a Perl-like manner. For specialist use there is also an alternative matching
1340    function, which is described
1341  .\" HTML <a href="#dfamatch">  .\" HTML <a href="#dfamatch">
1342  .\" </a>  .\" </a>
1343  below  below
# Line 1290  fields (not necessarily in this order): Line 1381  fields (not necessarily in this order):
1381  .sp  .sp
1382    unsigned long int \fIflags\fP;    unsigned long int \fIflags\fP;
1383    void *\fIstudy_data\fP;    void *\fIstudy_data\fP;
1384      void *\fIexecutable_jit\fP;
1385    unsigned long int \fImatch_limit\fP;    unsigned long int \fImatch_limit\fP;
1386    unsigned long int \fImatch_limit_recursion\fP;    unsigned long int \fImatch_limit_recursion\fP;
1387    void *\fIcallout_data\fP;    void *\fIcallout_data\fP;
# Line 1300  The \fIflags\fP field is a bitmap that s Line 1392  The \fIflags\fP field is a bitmap that s
1392  are set. The flag bits are:  are set. The flag bits are:
1393  .sp  .sp
1394    PCRE_EXTRA_STUDY_DATA    PCRE_EXTRA_STUDY_DATA
1395      PCRE_EXTRA_EXECUTABLE_JIT
1396    PCRE_EXTRA_MATCH_LIMIT    PCRE_EXTRA_MATCH_LIMIT
1397    PCRE_EXTRA_MATCH_LIMIT_RECURSION    PCRE_EXTRA_MATCH_LIMIT_RECURSION
1398    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_CALLOUT_DATA
1399    PCRE_EXTRA_TABLES    PCRE_EXTRA_TABLES
1400    PCRE_EXTRA_MARK    PCRE_EXTRA_MARK
1401  .sp  .sp
1402  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 and sometimes
1403  \fBpcre_extra\fP block that is returned by \fBpcre_study()\fP, together with  the \fIexecutable_jit\fP field are set in the \fBpcre_extra\fP block that is
1404  the appropriate flag bit. You should not set this yourself, but you may add to  returned by \fBpcre_study()\fP, together with the appropriate flag bits. You
1405  the block by setting the other fields and their corresponding flag bits.  should not set these yourself, but you may add to the block by setting the
1406    other fields and their corresponding flag bits.
1407  .P  .P
1408  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
1409  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,
1410  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
1411  classic example is a pattern that uses nested unlimited repeats.  classic example is a pattern that uses nested unlimited repeats.
1412  .P  .P
1413  Internally, PCRE uses a function called \fBmatch()\fP which it calls repeatedly  Internally, \fBpcre_exec()\fP uses a function called \fBmatch()\fP, which it
1414  (sometimes recursively). The limit set by \fImatch_limit\fP is imposed on the  calls repeatedly (sometimes recursively). The limit set by \fImatch_limit\fP is
1415  number of times this function is called during a match, which has the effect of  imposed on the number of times this function is called during a match, which
1416  limiting the amount of backtracking that can take place. For patterns that are  has the effect of limiting the amount of backtracking that can take place. For
1417  not anchored, the count restarts from zero for each position in the subject  patterns that are not anchored, the count restarts from zero for each position
1418  string.  in the subject string.
1419    .P
1420    When \fBpcre_exec()\fP is called with a pattern that was successfully studied
1421    with the PCRE_STUDY_JIT_COMPILE option, the way that the matching is executed
1422    is entirely different. However, there is still the possibility of runaway
1423    matching that goes on for a very long time, and so the \fImatch_limit\fP value
1424    is also used in this case (but in a different way) to limit how long the
1425    matching can continue.
1426  .P  .P
1427  The default value for the limit can be set when PCRE is built; the default  The default value for the limit can be set when PCRE is built; the default
1428  default is 10 million, which handles all but the most extreme cases. You can  default is 10 million, which handles all but the most extreme cases. You can
# Line 1336  limits the depth of recursion. The recur Line 1437  limits the depth of recursion. The recur
1437  total number of calls, because not all calls to \fBmatch()\fP are recursive.  total number of calls, because not all calls to \fBmatch()\fP are recursive.
1438  This limit is of use only if it is set smaller than \fImatch_limit\fP.  This limit is of use only if it is set smaller than \fImatch_limit\fP.
1439  .P  .P
1440  Limiting the recursion depth limits the amount of stack that can be used, or,  Limiting the recursion depth limits the amount of machine stack that can be
1441  when PCRE has been compiled to use memory on the heap instead of the stack, the  used, or, when PCRE has been compiled to use memory on the heap instead of the
1442  amount of heap memory that can be used.  stack, the amount of heap memory that can be used. This limit is not relevant,
1443    and is ignored, if the pattern was successfully studied with
1444    PCRE_STUDY_JIT_COMPILE.
1445  .P  .P
1446  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
1447  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 1397  zero. The only bits that may be set are Line 1500  zero. The only bits that may be set are
1500  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1501  PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and  PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and
1502  PCRE_PARTIAL_HARD.  PCRE_PARTIAL_HARD.
1503    .P
1504    If the pattern was successfully studied with the PCRE_STUDY_JIT_COMPILE option,
1505    the only supported options for JIT execution are PCRE_NO_UTF8_CHECK,
1506    PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, and PCRE_NOTEMPTY_ATSTART. Note in
1507    particular that partial matching is not supported. If an unsupported option is
1508    used, JIT execution is disabled and the normal interpretive code in
1509    \fBpcre_exec()\fP is run.
1510  .sp  .sp
1511    PCRE_ANCHORED    PCRE_ANCHORED
1512  .sp  .sp
# Line 1703  string that it matched that is returned. Line 1813  string that it matched that is returned.
1813  .P  .P
1814  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
1815  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
1816  returns a value of zero. If the substring offsets are not of interest,  returns a value of zero. If neither the actual string matched not any captured
1817  \fBpcre_exec()\fP may be called with \fIovector\fP passed as NULL and  substrings are of interest, \fBpcre_exec()\fP may be called with \fIovector\fP
1818  \fIovecsize\fP as zero. However, if the pattern contains back references and  passed as NULL and \fIovecsize\fP as zero. However, if the pattern contains
1819  the \fIovector\fP is not big enough to remember the related substrings, PCRE  back references and the \fIovector\fP is not big enough to remember the related
1820  has to get additional memory for use during matching. Thus it is usually  substrings, PCRE has to get additional memory for use during matching. Thus it
1821  advisable to supply an \fIovector\fP.  is usually advisable to supply an \fIovector\fP of reasonable size.
1822    .P
1823    There are some cases where zero is returned (indicating vector overflow) when
1824    in fact the vector is exactly the right size for the final match. For example,
1825    consider the pattern
1826    .sp
1827      (a)(?:(b)c|bd)
1828    .sp
1829    If a vector of 6 elements (allowing for only 1 captured substring) is given
1830    with subject string "abd", \fBpcre_exec()\fP will try to set the second
1831    captured string, thereby recording a vector overflow, before failing to match
1832    "c" and backing up to try the second alternative. The zero return, however,
1833    does correctly indicate that the maximum number of slots (namely 2) have been
1834    filled. In similar cases where there is temporary overflow, but the final
1835    number of used slots is actually less than the maximum, a non-zero value is
1836    returned.
1837  .P  .P
1838  The \fBpcre_fullinfo()\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
1839  subpatterns there are in a compiled pattern. The smallest size for  subpatterns there are in a compiled pattern. The smallest size for
# Line 1729  return from the function is 2, because t Line 1854  return from the function is 2, because t
1854  number is 1, and the offsets for for the second and third capturing subpatterns  number is 1, and the offsets for for the second and third capturing subpatterns
1855  (assuming the vector is large enough, of course) are set to -1.  (assuming the vector is large enough, of course) are set to -1.
1856  .P  .P
1857  \fBNote\fP: Elements of \fIovector\fP that do not correspond to capturing  \fBNote\fP: Elements in the first two-thirds of \fIovector\fP that do not
1858  parentheses in the pattern are never changed. That is, if a pattern contains  correspond to capturing parentheses in the pattern are never changed. That is,
1859  \fIn\fP capturing parentheses, no more than \fIovector[0]\fP to  if a pattern contains \fIn\fP capturing parentheses, no more than
1860  \fIovector[2n+1]\fP are set by \fBpcre_exec()\fP. The other elements retain  \fIovector[0]\fP to \fIovector[2n+1]\fP are set by \fBpcre_exec()\fP. The other
1861  whatever values they previously had.  elements (in the first two-thirds) retain whatever values they previously had.
1862  .P  .P
1863  Some convenience functions are provided for extracting the captured substrings  Some convenience functions are provided for extracting the captured substrings
1864  as separate strings. These are described below.  as separate strings. These are described below.
# Line 1885  in the subject string. Some simple patte Line 2010  in the subject string. Some simple patte
2010  faulted at compile time, but more complicated cases, in particular mutual  faulted at compile time, but more complicated cases, in particular mutual
2011  recursions between two different subpatterns, cannot be detected until run  recursions between two different subpatterns, cannot be detected until run
2012  time.  time.
2013    .sp
2014      PCRE_ERROR_JIT_STACKLIMIT (-27)
2015    .sp
2016    This error is returned when a pattern that was successfully studied using the
2017    PCRE_STUDY_JIT_COMPILE option is being matched, but the memory available for
2018    the just-in-time processing stack is not large enough. See the
2019    .\" HREF
2020    \fBpcrejit\fP
2021    .\"
2022    documentation for more details.
2023  .P  .P
2024  Error numbers -16 to -20 and -22 are not used by \fBpcre_exec()\fP.  Error numbers -16 to -20 and -22 are not used by \fBpcre_exec()\fP.
2025  .  .
# Line 2125  names are not included in the compiled c Line 2260  names are not included in the compiled c
2260  numbers. For this reason, the use of different names for subpatterns of the  numbers. For this reason, the use of different names for subpatterns of the
2261  same number causes an error at compile time.  same number causes an error at compile time.
2262  .  .
2263    .
2264  .SH "DUPLICATE SUBPATTERN NAMES"  .SH "DUPLICATE SUBPATTERN NAMES"
2265  .rs  .rs
2266  .sp  .sp
# Line 2324  returns data, even though the meaning of Line 2460  returns data, even though the meaning of
2460  The strings are returned in reverse order of length; that is, the longest  The strings are returned in reverse order of length; that is, the longest
2461  matching string is given first. If there were too many matches to fit into  matching string is given first. If there were too many matches to fit into
2462  \fIovector\fP, the yield of the function is zero, and the vector is filled with  \fIovector\fP, the yield of the function is zero, and the vector is filled with
2463  the longest matches.  the longest matches. Unlike \fBpcre_exec()\fP, \fBpcre_dfa_exec()\fP can use
2464    the entire \fIovector\fP for returning matched strings.
2465  .  .
2466  .  .
2467  .SS "Error returns from \fBpcre_dfa_exec()\fP"  .SS "Error returns from \fBpcre_dfa_exec()\fP"
# Line 2354  group. These are not supported. Line 2491  group. These are not supported.
2491    PCRE_ERROR_DFA_UMLIMIT    (-18)    PCRE_ERROR_DFA_UMLIMIT    (-18)
2492  .sp  .sp
2493  This return is given if \fBpcre_dfa_exec()\fP is called with an \fIextra\fP  This return is given if \fBpcre_dfa_exec()\fP is called with an \fIextra\fP
2494  block that contains a setting of the \fImatch_limit\fP field. This is not  block that contains a setting of the \fImatch_limit\fP or
2495  supported (it is meaningless).  \fImatch_limit_recursion\fP fields. This is not supported (these fields are
2496    meaningless for DFA matching).
2497  .sp  .sp
2498    PCRE_ERROR_DFA_WSSIZE     (-19)    PCRE_ERROR_DFA_WSSIZE     (-19)
2499  .sp  .sp
# Line 2392  Cambridge CB2 3QH, England. Line 2530  Cambridge CB2 3QH, England.
2530  .rs  .rs
2531  .sp  .sp
2532  .nf  .nf
2533  Last updated: 13 August 2011  Last updated: 23 September 2011
2534  Copyright (c) 1997-2011 University of Cambridge.  Copyright (c) 1997-2011 University of Cambridge.
2535  .fi  .fi

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