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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 148  just use different data types for their Line 148  just use different data types for their
148  start with \fBpcre16_\fP instead of \fBpcre_\fP. For every option that has UTF8  start with \fBpcre16_\fP instead of \fBpcre_\fP. For every option that has UTF8
149  in its name (for example, PCRE_UTF8), there is a corresponding 16-bit name with  in its name (for example, PCRE_UTF8), there is a corresponding 16-bit name with
150  UTF8 replaced by UTF16. This facility is in fact just cosmetic; the 16-bit  UTF8 replaced by UTF16. This facility is in fact just cosmetic; the 16-bit
151  option names define the same bit values.  option names define the same bit values.
152  .P  .P
153  References to bytes and UTF-8 in this document should be read as references to  References to bytes and UTF-8 in this document should be read as references to
154  16-bit data quantities and UTF-16 when using the 16-bit library, unless  16-bit data quantities and UTF-16 when using the 16-bit library, unless
# Line 157  library are given in the Line 157  library are given in the
157  .\" HREF  .\" HREF
158  \fBpcre16\fP  \fBpcre16\fP
159  .\"  .\"
160  page.  page.
161  .  .
162  .  .
163  .SH "PCRE API OVERVIEW"  .SH "PCRE API OVERVIEW"
# 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 392  not recognized. The following informatio Line 392  not recognized. The following informatio
392    PCRE_CONFIG_UTF8    PCRE_CONFIG_UTF8
393  .sp  .sp
394  The output is an integer that is set to one if UTF-8 support is available;  The output is an integer that is set to one if UTF-8 support is available;
395  otherwise it is set to zero. If this option is given to the 16-bit version of  otherwise it is set to zero. If this option is given to the 16-bit version of
396  this function, \fBpcre16_config()\fP, the result is PCRE_ERROR_BADOPTION.  this function, \fBpcre16_config()\fP, the result is PCRE_ERROR_BADOPTION.
397  .sp  .sp
398    PCRE_CONFIG_UTF16    PCRE_CONFIG_UTF16
# Line 412  properties is available; otherwise it is Line 412  properties is available; otherwise it is
412  The output is an integer that is set to one if support for just-in-time  The output is an integer that is set to one if support for just-in-time
413  compiling is available; otherwise it is set to zero.  compiling is available; otherwise it is set to zero.
414  .sp  .sp
415      PCRE_CONFIG_JITTARGET
416    .sp
417    The output is a pointer to a zero-terminated "const char *" string. If JIT
418    support is available, the string contains the name of the architecture for
419    which the JIT compiler is configured, for example "x86 32bit (little endian +
420    unaligned)". If JIT support is not available, the result is NULL.
421    .sp
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 519  documentation). For those options that c Line 528  documentation). For those options that c
528  the pattern, the contents of the \fIoptions\fP argument specifies their  the pattern, the contents of the \fIoptions\fP argument specifies their
529  settings at the start of compilation and execution. The PCRE_ANCHORED,  settings at the start of compilation and execution. The PCRE_ANCHORED,
530  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
531  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
532  compile time.  compile time.
533  .P  .P
534  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.  If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
# Line 635  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 654  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 732  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 746  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 812  page. Line 833  page.
833  .sp  .sp
834    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
835  .sp  .sp
836  When PCRE_UTF8 is set, the validity of the pattern as a UTF-8  When PCRE_UTF8 is set, the validity of the pattern as a UTF-8
837  string is automatically checked. There is a discussion about the  string is automatically checked. There is a discussion about the
838  .\" HTML <a href="pcreunicode.html#utf8strings">  .\" HTML <a href="pcreunicode.html#utf8strings">
839  .\" </a>  .\" </a>
840  validity of UTF-8 strings  validity of UTF-8 strings
841  .\"  .\"
842  in the  in the
843  .\" HREF  .\" HREF
# Line 836  validity checking of subject strings. Line 857  validity checking of subject strings.
857  .sp  .sp
858  The following table lists the error codes than may be returned by  The following table lists the error codes than may be returned by
859  \fBpcre_compile2()\fP, along with the error messages that may be returned by  \fBpcre_compile2()\fP, along with the error messages that may be returned by
860  both compiling functions. Note that error messages are always 8-bit ASCII  both compiling functions. Note that error messages are always 8-bit ASCII
861  strings, even in 16-bit mode. As PCRE has developed, some error codes have  strings, even in 16-bit mode. As PCRE has developed, some error codes have
862  fallen out of use. To avoid confusion, they have not been re-used.  fallen out of use. To avoid confusion, they have not been re-used.
863  .sp  .sp
# Line 910  fallen out of use. To avoid confusion, t Line 931  fallen out of use. To avoid confusion, t
931    65  different names for subpatterns of the same number are    65  different names for subpatterns of the same number are
932          not allowed          not allowed
933    66  (*MARK) must have an argument    66  (*MARK) must have an argument
934    67  this version of PCRE is not compiled with Unicode property    67  this version of PCRE is not compiled with Unicode property
935          support          support
936    68  \ec must be followed by an ASCII character    68  \ec must be followed by an ASCII character
937    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
938    70  internal error: unknown opcode in find_fixedlength()    70  internal error: unknown opcode in find_fixedlength()
939    71  \eN is not supported in a class    71  \eN is not supported in a class
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 951  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  .P  if \fBpcre_study()\fP is called with the PCRE_STUDY_EXTRA_NEEDED option, it
981  The second argument of \fBpcre_study()\fP contains option bits. There is only  returns a \fBpcre_extra\fP block even if studying did not find any additional
982  one option: PCRE_STUDY_JIT_COMPILE. If this is set, and the just-in-time  information. It may still return NULL, however, if an error occurs in
983  compiler is available, the pattern is further compiled into machine code that  \fBpcre_study()\fP.
984  executes much faster than the \fBpcre_exec()\fP matching function. If  .P
985  the just-in-time compiler is not available, this option is ignored. All other  The second argument of \fBpcre_study()\fP contains option bits. There are three
986  bits in the \fIoptions\fP argument must be zero.  further options in addition to PCRE_STUDY_EXTRA_NEEDED:
987    .sp
988      PCRE_STUDY_JIT_COMPILE
989      PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
990      PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
991    .sp
992    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
994    the \fBpcre_exec()\fP interpretive matching function. If the just-in-time
995    compiler is not available, these options are ignored. All undefined bits in the
996    \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
999  patterns to be analyzed, and for one-off matches and simple patterns the  patterns to be analyzed, and for one-off matches and simple patterns the
# Line 984  When you are finished with a pattern, yo Line 1017  When you are finished with a pattern, yo
1017  study data by calling \fBpcre_free_study()\fP. This function was added to the  study data by calling \fBpcre_free_study()\fP. This function was added to the
1018  API for release 8.20. For earlier versions, the memory could be freed with  API for release 8.20. For earlier versions, the memory could be freed with
1019  \fBpcre_free()\fP, just like the pattern itself. This will still work in cases  \fBpcre_free()\fP, just like the pattern itself. This will still work in cases
1020  where PCRE_STUDY_JIT_COMPILE is not used, but it is advisable to change to the  where JIT optimization is not used, but it is advisable to change to the new
1021  new function when convenient.  function when convenient.
1022  .P  .P
1023  This is a typical way in which \fBpcre_study\fP() is used (except that in a  This is a typical way in which \fBpcre_study\fP() is used (except that in a
1024  real application there should be tests for errors):  real application there should be tests for errors):
# Line 1007  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 1018  created. This speeds up finding a positi Line 1050  created. This speeds up finding a positi
1050  matching. (In 16-bit mode, the bitmap is used for 16-bit values less than 256.)  matching. (In 16-bit mode, the bitmap is used for 16-bit values less than 256.)
1051  .P  .P
1052  These two optimizations apply to both \fBpcre_exec()\fP and  These two optimizations apply to both \fBpcre_exec()\fP and
1053  \fBpcre_dfa_exec()\fP. However, they are not used by \fBpcre_exec()\fP if  \fBpcre_dfa_exec()\fP, and the information is also used by the JIT compiler.
1054  \fBpcre_study()\fP is called with the PCRE_STUDY_JIT_COMPILE option, and  The optimizations can be disabled by setting the PCRE_NO_START_OPTIMIZE option
1055  just-in-time compiling is successful. The optimizations can be disabled by  when calling \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP, but if this is done,
1056  setting the PCRE_NO_START_OPTIMIZE option when calling \fBpcre_exec()\fP or  JIT execution is also disabled. You might want to do this if your pattern
1057  \fBpcre_dfa_exec()\fP. You might want to do this if your pattern contains  contains callouts or (*MARK) and you want to make use of these facilities in
1058  callouts or (*MARK) (which cannot be handled by the JIT compiler), and you want  cases where matching fails. See the discussion of PCRE_NO_START_OPTIMIZE
 to make use of these facilities in cases where matching fails. See the  
 discussion of PCRE_NO_START_OPTIMIZE  
1059  .\" HTML <a href="#execoptions">  .\" HTML <a href="#execoptions">
1060  .\" </a>  .\" </a>
1061  below.  below.
# Line 1113  the following negative numbers: Line 1143  the following negative numbers:
1143    PCRE_ERROR_NULL           the argument \fIcode\fP was NULL    PCRE_ERROR_NULL           the argument \fIcode\fP was NULL
1144                              the argument \fIwhere\fP was NULL                              the argument \fIwhere\fP was NULL
1145    PCRE_ERROR_BADMAGIC       the "magic number" was not found    PCRE_ERROR_BADMAGIC       the "magic number" was not found
1146    PCRE_ERROR_BADENDIANNESS  the pattern was compiled with different    PCRE_ERROR_BADENDIANNESS  the pattern was compiled with different
1147                              endianness                              endianness
1148    PCRE_ERROR_BADOPTION      the value of \fIwhat\fP was invalid    PCRE_ERROR_BADOPTION      the value of \fIwhat\fP was invalid
1149  .sp  .sp
1150  The "magic number" is placed at the start of each compiled pattern as an simple  The "magic number" is placed at the start of each compiled pattern as an simple
1151  check against passing an arbitrary memory pointer. The endianness error can  check against passing an arbitrary memory pointer. The endianness error can
1152  occur if a compiled pattern is saved and reloaded on a different host. Here is  occur if a compiled pattern is saved and reloaded on a different host. Here is
1153  a typical call of \fBpcre_fullinfo()\fP, to obtain the length of the compiled  a typical call of \fBpcre_fullinfo()\fP, to obtain the length of the compiled
1154  pattern:  pattern:
# Line 1161  where data units are bytes.) The fourth Line 1191  where data units are bytes.) The fourth
1191  variable.  variable.
1192  .P  .P
1193  If there is a fixed first value, for example, the letter "c" from a pattern  If there is a fixed first value, for example, the letter "c" from a pattern
1194  such as (cat|cow|coyote), its value is returned. In the 8-bit library, the  such as (cat|cow|coyote), its value is returned. In the 8-bit library, the
1195  value is always less than 256; in the 16-bit library the value can be up to  value is always less than 256; in the 16-bit library the value can be up to
1196  0xffff.  0xffff.
1197  .P  .P
1198  If there is no fixed first value, and if either  If there is no fixed first value, and if either
# Line 1198  Return 1 if the (?J) or (?-J) option set Line 1228  Return 1 if the (?J) or (?-J) option set
1228  .sp  .sp
1229    PCRE_INFO_JIT    PCRE_INFO_JIT
1230  .sp  .sp
1231  Return 1 if the pattern was studied with the PCRE_STUDY_JIT_COMPILE option, and  Return 1 if the pattern was studied with one of the JIT options, and
1232  just-in-time compiling was successful. The fourth argument should point to an  just-in-time compiling was successful. The fourth argument should point to an
1233  \fBint\fP variable. A return value of 0 means that JIT support is not available  \fBint\fP variable. A return value of 0 means that JIT support is not available
1234  in this version of PCRE, or that the pattern was not studied with the  in this version of PCRE, or that the pattern was not studied with a JIT option,
1235  PCRE_STUDY_JIT_COMPILE option, or that the JIT compiler could not handle this  or that the JIT compiler could not handle this particular pattern. See the
 particular pattern. See the  
1236  .\" HREF  .\" HREF
1237  \fBpcrejit\fP  \fBpcrejit\fP
1238  .\"  .\"
# Line 1211  documentation for details of what can an Line 1240  documentation for details of what can an
1240  .sp  .sp
1241    PCRE_INFO_JITSIZE    PCRE_INFO_JITSIZE
1242  .sp  .sp
1243  If the pattern was successfully studied with the PCRE_STUDY_JIT_COMPILE option,  If the pattern was successfully studied with a JIT option, return the size of
1244  return the size of the JIT compiled code, otherwise return zero. The fourth  the JIT compiled code, otherwise return zero. The fourth argument should point
1245  argument should point to a \fBsize_t\fP variable.  to a \fBsize_t\fP variable.
1246  .sp  .sp
1247    PCRE_INFO_LASTLITERAL    PCRE_INFO_LASTLITERAL
1248  .sp  .sp
# Line 1225  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 1452  fields (not necessarily in this order): Line 1488  fields (not necessarily in this order):
1488    const unsigned char *\fItables\fP;    const unsigned char *\fItables\fP;
1489    unsigned char **\fImark\fP;    unsigned char **\fImark\fP;
1490  .sp  .sp
1491  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
1492  "PCRE_SCHAR16 **".  "PCRE_UCHAR16 **".
1493  .P  .P
1494  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
1495  are set. The flag bits are:  flag bits are:
1496  .sp  .sp
1497    PCRE_EXTRA_STUDY_DATA    PCRE_EXTRA_CALLOUT_DATA
1498    PCRE_EXTRA_EXECUTABLE_JIT    PCRE_EXTRA_EXECUTABLE_JIT
1499      PCRE_EXTRA_MARK
1500    PCRE_EXTRA_MATCH_LIMIT    PCRE_EXTRA_MATCH_LIMIT
1501    PCRE_EXTRA_MATCH_LIMIT_RECURSION    PCRE_EXTRA_MATCH_LIMIT_RECURSION
1502    PCRE_EXTRA_CALLOUT_DATA    PCRE_EXTRA_STUDY_DATA
1503    PCRE_EXTRA_TABLES    PCRE_EXTRA_TABLES
   PCRE_EXTRA_MARK  
1504  .sp  .sp
1505  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
1506  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
1507  returned by \fBpcre_study()\fP, together with the appropriate flag bits. You  returned by \fBpcre_study()\fP, together with the appropriate flag bits. You
1508  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
1509  other fields and their corresponding flag bits.  fields and their corresponding flag bits.
1510  .P  .P
1511  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
1512  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 1485  patterns that are not anchored, the coun Line 1521  patterns that are not anchored, the coun
1521  in the subject string.  in the subject string.
1522  .P  .P
1523  When \fBpcre_exec()\fP is called with a pattern that was successfully studied  When \fBpcre_exec()\fP is called with a pattern that was successfully studied
1524  with the PCRE_STUDY_JIT_COMPILE option, the way that the matching is executed  with a JIT option, the way that the matching is executed is entirely different.
1525  is entirely different. However, there is still the possibility of runaway  However, there is still the possibility of runaway matching that goes on for a
1526  matching that goes on for a very long time, and so the \fImatch_limit\fP value  very long time, and so the \fImatch_limit\fP value is also used in this case
1527  is also used in this case (but in a different way) to limit how long the  (but in a different way) to limit how long the matching can continue.
 matching can continue.  
1528  .P  .P
1529  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
1530  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 1507  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, if the pattern was successfully studied with  and is ignored, when matching is done using JIT compiled code.
 PCRE_STUDY_JIT_COMPILE.  
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 1565  documentation. Line 1599  documentation.
1599  The unused bits of the \fIoptions\fP argument for \fBpcre_exec()\fP must be  The unused bits of the \fIoptions\fP argument for \fBpcre_exec()\fP must be
1600  zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_\fIxxx\fP,  zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_\fIxxx\fP,
1601  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1602  PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and  PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_HARD, and
1603  PCRE_PARTIAL_HARD.  PCRE_PARTIAL_SOFT.
1604  .P  .P
1605  If the pattern was successfully studied with the PCRE_STUDY_JIT_COMPILE option,  If the pattern was successfully studied with one of the just-in-time (JIT)
1606  the only supported options for JIT execution are PCRE_NO_UTF8_CHECK,  compile options, the only supported options for JIT execution are
1607  PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, and PCRE_NOTEMPTY_ATSTART. Note in  PCRE_NO_UTF8_CHECK, PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY,
1608  particular that partial matching is not supported. If an unsupported option is  PCRE_NOTEMPTY_ATSTART, PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT. If an
1609  used, JIT execution is disabled and the normal interpretive code in  unsupported option is used, JIT execution is disabled and the normal
1610  \fBpcre_exec()\fP is run.  interpretive code in \fBpcre_exec()\fP is run.
1611  .sp  .sp
1612    PCRE_ANCHORED    PCRE_ANCHORED
1613  .sp  .sp
# Line 1692  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.  time. The use of PCRE_NO_START_OPTIMIZE disables JIT execution; when it is set,
1730    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.
1733  Consider the pattern  Consider the pattern
# Line 1725  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 1875  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 2075  time. Line 2115  time.
2115  .sp  .sp
2116    PCRE_ERROR_JIT_STACKLIMIT (-27)    PCRE_ERROR_JIT_STACKLIMIT (-27)
2117  .sp  .sp
2118  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
2119  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
2120  the just-in-time processing stack is not large enough. See the  just-in-time processing stack is not large enough. See the
2121  .\" HREF  .\" HREF
2122  \fBpcrejit\fP  \fBpcrejit\fP
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>
2142  .SS "Reason codes for invalid UTF-8 strings"  .SS "Reason codes for invalid UTF-8 strings"
2143  .rs  .rs
2144  .sp  .sp
2145  This section applies only to the 8-bit library. The corresponding information  This section applies only to the 8-bit library. The corresponding information
2146  for the 16-bit library is given in the  for the 16-bit library is given in the
2147  .\" HREF  .\" HREF
2148  \fBpcre16\fP  \fBpcre16\fP
# Line 2406  other alternatives. Ultimately, when it Line 2446  other alternatives. Ultimately, when it
2446  will yield PCRE_ERROR_NOMATCH.  will yield PCRE_ERROR_NOMATCH.
2447  .  .
2448  .  .
2449    .SH "OBTAINING AN ESTIMATE OF STACK USAGE"
2450    .rs
2451    .sp
2452    Matching certain patterns using \fBpcre_exec()\fP can use a lot of process
2453    stack, which in certain environments can be rather limited in size. Some users
2454    find it helpful to have an estimate of the amount of stack that is used by
2455    \fBpcre_exec()\fP, to help them set recursion limits, as described in the
2456    .\" HREF
2457    \fBpcrestack\fP
2458    .\"
2459    documentation. The estimate that is output by \fBpcretest\fP when called with
2460    the \fB-m\fP and \fB-C\fP options is obtained by calling \fBpcre_exec\fP with
2461    the values NULL, NULL, NULL, -999, and -999 for its first five arguments.
2462    .P
2463    Normally, if its first argument is NULL, \fBpcre_exec()\fP immediately returns
2464    the negative error code PCRE_ERROR_NULL, but with this special combination of
2465    arguments, it returns instead a negative number whose absolute value is the
2466    approximate stack frame size in bytes. (A negative number is used so that it is
2467    clear that no match has happened.) The value is approximate because in some
2468    cases, recursive calls to \fBpcre_exec()\fP occur when there are one or two
2469    additional variables on the stack.
2470    .P
2471    If PCRE has been compiled to use the heap instead of the stack for recursion,
2472    the value returned is the size of each block that is obtained from the heap.
2473    .
2474    .
2475  .\" HTML <a name="dfamatch"></a>  .\" HTML <a name="dfamatch"></a>
2476  .SH "MATCHING A PATTERN: THE ALTERNATIVE FUNCTION"  .SH "MATCHING A PATTERN: THE ALTERNATIVE FUNCTION"
2477  .rs  .rs
# Line 2587  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 2611  Cambridge CB2 3QH, England. Line 2684  Cambridge CB2 3QH, England.
2684  .rs  .rs
2685  .sp  .sp
2686  .nf  .nf
2687  Last updated: 07 January 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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