Annotation of embedaddon/pcre/doc/pcreapi.3, revision 1.1.1.4

1.1.1.4 ! misho       1: .TH PCREAPI 3 "12 May 2013" "PCRE 8.33"
1.1       misho       2: .SH NAME
                      3: PCRE - Perl-compatible regular expressions
1.1.1.2   misho       4: .sp
                      5: .B #include <pcre.h>
                      6: .
                      7: .
1.1       misho       8: .SH "PCRE NATIVE API BASIC FUNCTIONS"
                      9: .rs
                     10: .sp
                     11: .SM
                     12: .B pcre *pcre_compile(const char *\fIpattern\fP, int \fIoptions\fP,
                     13: .ti +5n
                     14: .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
                     15: .ti +5n
                     16: .B const unsigned char *\fItableptr\fP);
                     17: .PP
                     18: .B pcre *pcre_compile2(const char *\fIpattern\fP, int \fIoptions\fP,
                     19: .ti +5n
                     20: .B int *\fIerrorcodeptr\fP,
                     21: .ti +5n
                     22: .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
                     23: .ti +5n
                     24: .B const unsigned char *\fItableptr\fP);
                     25: .PP
                     26: .B pcre_extra *pcre_study(const pcre *\fIcode\fP, int \fIoptions\fP,
                     27: .ti +5n
                     28: .B const char **\fIerrptr\fP);
                     29: .PP
                     30: .B void pcre_free_study(pcre_extra *\fIextra\fP);
                     31: .PP
                     32: .B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
                     33: .ti +5n
                     34: .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
                     35: .ti +5n
                     36: .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);
                     37: .PP
                     38: .B int pcre_dfa_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
                     39: .ti +5n
                     40: .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
                     41: .ti +5n
                     42: .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,
                     43: .ti +5n
                     44: .B int *\fIworkspace\fP, int \fIwscount\fP);
1.1.1.2   misho      45: .
                     46: .
                     47: .SH "PCRE NATIVE API STRING EXTRACTION FUNCTIONS"
                     48: .rs
                     49: .sp
1.1       misho      50: .B int pcre_copy_named_substring(const pcre *\fIcode\fP,
                     51: .ti +5n
                     52: .B const char *\fIsubject\fP, int *\fIovector\fP,
                     53: .ti +5n
                     54: .B int \fIstringcount\fP, const char *\fIstringname\fP,
                     55: .ti +5n
                     56: .B char *\fIbuffer\fP, int \fIbuffersize\fP);
                     57: .PP
                     58: .B int pcre_copy_substring(const char *\fIsubject\fP, int *\fIovector\fP,
                     59: .ti +5n
                     60: .B int \fIstringcount\fP, int \fIstringnumber\fP, char *\fIbuffer\fP,
                     61: .ti +5n
                     62: .B int \fIbuffersize\fP);
                     63: .PP
                     64: .B int pcre_get_named_substring(const pcre *\fIcode\fP,
                     65: .ti +5n
                     66: .B const char *\fIsubject\fP, int *\fIovector\fP,
                     67: .ti +5n
                     68: .B int \fIstringcount\fP, const char *\fIstringname\fP,
                     69: .ti +5n
                     70: .B const char **\fIstringptr\fP);
                     71: .PP
                     72: .B int pcre_get_stringnumber(const pcre *\fIcode\fP,
                     73: .ti +5n
                     74: .B const char *\fIname\fP);
                     75: .PP
                     76: .B int pcre_get_stringtable_entries(const pcre *\fIcode\fP,
                     77: .ti +5n
                     78: .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);
                     79: .PP
                     80: .B int pcre_get_substring(const char *\fIsubject\fP, int *\fIovector\fP,
                     81: .ti +5n
                     82: .B int \fIstringcount\fP, int \fIstringnumber\fP,
                     83: .ti +5n
                     84: .B const char **\fIstringptr\fP);
                     85: .PP
                     86: .B int pcre_get_substring_list(const char *\fIsubject\fP,
                     87: .ti +5n
                     88: .B int *\fIovector\fP, int \fIstringcount\fP, "const char ***\fIlistptr\fP);"
                     89: .PP
                     90: .B void pcre_free_substring(const char *\fIstringptr\fP);
                     91: .PP
                     92: .B void pcre_free_substring_list(const char **\fIstringptr\fP);
1.1.1.2   misho      93: .
                     94: .
                     95: .SH "PCRE NATIVE API AUXILIARY FUNCTIONS"
                     96: .rs
                     97: .sp
1.1.1.4 ! misho      98: .B int pcre_jit_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
        !            99: .ti +5n
        !           100: .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
        !           101: .ti +5n
        !           102: .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,
        !           103: .ti +5n
        !           104: .B pcre_jit_stack *\fIjstack\fP);
        !           105: .PP
1.1.1.2   misho     106: .B pcre_jit_stack *pcre_jit_stack_alloc(int \fIstartsize\fP, int \fImaxsize\fP);
                    107: .PP
                    108: .B void pcre_jit_stack_free(pcre_jit_stack *\fIstack\fP);
                    109: .PP
                    110: .B void pcre_assign_jit_stack(pcre_extra *\fIextra\fP,
                    111: .ti +5n
                    112: .B pcre_jit_callback \fIcallback\fP, void *\fIdata\fP);
1.1       misho     113: .PP
                    114: .B const unsigned char *pcre_maketables(void);
                    115: .PP
                    116: .B int pcre_fullinfo(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
                    117: .ti +5n
                    118: .B int \fIwhat\fP, void *\fIwhere\fP);
                    119: .PP
                    120: .B int pcre_refcount(pcre *\fIcode\fP, int \fIadjust\fP);
                    121: .PP
                    122: .B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);
                    123: .PP
1.1.1.2   misho     124: .B const char *pcre_version(void);
                    125: .PP
                    126: .B int pcre_pattern_to_host_byte_order(pcre *\fIcode\fP,
                    127: .ti +5n
                    128: .B pcre_extra *\fIextra\fP, const unsigned char *\fItables\fP);
1.1       misho     129: .
                    130: .
                    131: .SH "PCRE NATIVE API INDIRECTED FUNCTIONS"
                    132: .rs
                    133: .sp
                    134: .B void *(*pcre_malloc)(size_t);
                    135: .PP
                    136: .B void (*pcre_free)(void *);
                    137: .PP
                    138: .B void *(*pcre_stack_malloc)(size_t);
                    139: .PP
                    140: .B void (*pcre_stack_free)(void *);
                    141: .PP
                    142: .B int (*pcre_callout)(pcre_callout_block *);
                    143: .
                    144: .
1.1.1.4 ! misho     145: .SH "PCRE 8-BIT, 16-BIT, AND 32-BIT LIBRARIES"
1.1.1.2   misho     146: .rs
                    147: .sp
1.1.1.4 ! misho     148: As well as support for 8-bit character strings, PCRE also supports 16-bit
        !           149: strings (from release 8.30) and 32-bit strings (from release 8.32), by means of
        !           150: two additional libraries. They can be built as well as, or instead of, the
        !           151: 8-bit library. To avoid too much complication, this document describes the
        !           152: 8-bit versions of the functions, with only occasional references to the 16-bit
        !           153: and 32-bit libraries.
        !           154: .P
        !           155: The 16-bit and 32-bit functions operate in the same way as their 8-bit
        !           156: counterparts; they just use different data types for their arguments and
        !           157: results, and their names start with \fBpcre16_\fP or \fBpcre32_\fP instead of
        !           158: \fBpcre_\fP. For every option that has UTF8 in its name (for example,
        !           159: PCRE_UTF8), there are corresponding 16-bit and 32-bit names with UTF8 replaced
        !           160: by UTF16 or UTF32, respectively. This facility is in fact just cosmetic; the
        !           161: 16-bit and 32-bit option names define the same bit values.
1.1.1.2   misho     162: .P
                    163: References to bytes and UTF-8 in this document should be read as references to
1.1.1.4 ! misho     164: 16-bit data units and UTF-16 when using the 16-bit library, or 32-bit data
        !           165: units and UTF-32 when using the 32-bit library, unless specified otherwise.
        !           166: More details of the specific differences for the 16-bit and 32-bit libraries
        !           167: are given in the
1.1.1.2   misho     168: .\" HREF
                    169: \fBpcre16\fP
                    170: .\"
1.1.1.4 ! misho     171: and
        !           172: .\" HREF
        !           173: \fBpcre32\fP
        !           174: .\"
        !           175: pages.
1.1.1.2   misho     176: .
                    177: .
1.1       misho     178: .SH "PCRE API OVERVIEW"
                    179: .rs
                    180: .sp
                    181: PCRE has its own native API, which is described in this document. There are
1.1.1.2   misho     182: also some wrapper functions (for the 8-bit library only) that correspond to the
                    183: POSIX regular expression API, but they do not give access to all the
                    184: functionality. They are described in the
1.1       misho     185: .\" HREF
                    186: \fBpcreposix\fP
                    187: .\"
                    188: documentation. Both of these APIs define a set of C function calls. A C++
1.1.1.2   misho     189: wrapper (again for the 8-bit library only) is also distributed with PCRE. It is
                    190: documented in the
1.1       misho     191: .\" HREF
                    192: \fBpcrecpp\fP
                    193: .\"
                    194: page.
                    195: .P
                    196: The native API C function prototypes are defined in the header file
1.1.1.2   misho     197: \fBpcre.h\fP, and on Unix-like systems the (8-bit) library itself is called
                    198: \fBlibpcre\fP. It can normally be accessed by adding \fB-lpcre\fP to the
                    199: command for linking an application that uses PCRE. The header file defines the
                    200: macros PCRE_MAJOR and PCRE_MINOR to contain the major and minor release numbers
                    201: for the library. Applications can use these to include support for different
                    202: releases of PCRE.
1.1       misho     203: .P
                    204: In a Windows environment, if you want to statically link an application program
                    205: against a non-dll \fBpcre.a\fP file, you must define PCRE_STATIC before
                    206: including \fBpcre.h\fP or \fBpcrecpp.h\fP, because otherwise the
                    207: \fBpcre_malloc()\fP and \fBpcre_free()\fP exported functions will be declared
                    208: \fB__declspec(dllimport)\fP, with unwanted results.
                    209: .P
                    210: The functions \fBpcre_compile()\fP, \fBpcre_compile2()\fP, \fBpcre_study()\fP,
                    211: and \fBpcre_exec()\fP are used for compiling and matching regular expressions
                    212: in a Perl-compatible manner. A sample program that demonstrates the simplest
                    213: way of using them is provided in the file called \fIpcredemo.c\fP in the PCRE
                    214: source distribution. A listing of this program is given in the
                    215: .\" HREF
                    216: \fBpcredemo\fP
                    217: .\"
                    218: documentation, and the
                    219: .\" HREF
                    220: \fBpcresample\fP
                    221: .\"
                    222: documentation describes how to compile and run it.
                    223: .P
                    224: Just-in-time compiler support is an optional feature of PCRE that can be built
                    225: in appropriate hardware environments. It greatly speeds up the matching
                    226: performance of many patterns. Simple programs can easily request that it be
                    227: used if available, by setting an option that is ignored when it is not
                    228: relevant. More complicated programs might need to make use of the functions
                    229: \fBpcre_jit_stack_alloc()\fP, \fBpcre_jit_stack_free()\fP, and
                    230: \fBpcre_assign_jit_stack()\fP in order to control the JIT code's memory usage.
1.1.1.4 ! misho     231: .P
        !           232: From release 8.32 there is also a direct interface for JIT execution, which
        !           233: gives improved performance. The JIT-specific functions are discussed in the
1.1       misho     234: .\" HREF
                    235: \fBpcrejit\fP
                    236: .\"
                    237: documentation.
                    238: .P
                    239: A second matching function, \fBpcre_dfa_exec()\fP, which is not
                    240: Perl-compatible, is also provided. This uses a different algorithm for the
                    241: matching. The alternative algorithm finds all possible matches (at a given
                    242: point in the subject), and scans the subject just once (unless there are
                    243: lookbehind assertions). However, this algorithm does not return captured
                    244: substrings. A description of the two matching algorithms and their advantages
                    245: and disadvantages is given in the
                    246: .\" HREF
                    247: \fBpcrematching\fP
                    248: .\"
                    249: documentation.
                    250: .P
                    251: In addition to the main compiling and matching functions, there are convenience
                    252: functions for extracting captured substrings from a subject string that is
                    253: matched by \fBpcre_exec()\fP. They are:
                    254: .sp
                    255:   \fBpcre_copy_substring()\fP
                    256:   \fBpcre_copy_named_substring()\fP
                    257:   \fBpcre_get_substring()\fP
                    258:   \fBpcre_get_named_substring()\fP
                    259:   \fBpcre_get_substring_list()\fP
                    260:   \fBpcre_get_stringnumber()\fP
                    261:   \fBpcre_get_stringtable_entries()\fP
                    262: .sp
                    263: \fBpcre_free_substring()\fP and \fBpcre_free_substring_list()\fP are also
                    264: provided, to free the memory used for extracted strings.
                    265: .P
                    266: The function \fBpcre_maketables()\fP is used to build a set of character tables
                    267: in the current locale for passing to \fBpcre_compile()\fP, \fBpcre_exec()\fP,
                    268: or \fBpcre_dfa_exec()\fP. This is an optional facility that is provided for
                    269: specialist use. Most commonly, no special tables are passed, in which case
                    270: internal tables that are generated when PCRE is built are used.
                    271: .P
                    272: The function \fBpcre_fullinfo()\fP is used to find out information about a
1.1.1.2   misho     273: compiled pattern. The function \fBpcre_version()\fP returns a pointer to a
                    274: string containing the version of PCRE and its date of release.
1.1       misho     275: .P
                    276: The function \fBpcre_refcount()\fP maintains a reference count in a data block
                    277: containing a compiled pattern. This is provided for the benefit of
                    278: object-oriented applications.
                    279: .P
                    280: The global variables \fBpcre_malloc\fP and \fBpcre_free\fP initially contain
                    281: the entry points of the standard \fBmalloc()\fP and \fBfree()\fP functions,
                    282: respectively. PCRE calls the memory management functions via these variables,
                    283: so a calling program can replace them if it wishes to intercept the calls. This
                    284: should be done before calling any PCRE functions.
                    285: .P
                    286: The global variables \fBpcre_stack_malloc\fP and \fBpcre_stack_free\fP are also
                    287: indirections to memory management functions. These special functions are used
                    288: only when PCRE is compiled to use the heap for remembering data, instead of
                    289: recursive function calls, when running the \fBpcre_exec()\fP function. See the
                    290: .\" HREF
                    291: \fBpcrebuild\fP
                    292: .\"
                    293: documentation for details of how to do this. It is a non-standard way of
                    294: building PCRE, for use in environments that have limited stacks. Because of the
                    295: greater use of memory management, it runs more slowly. Separate functions are
                    296: provided so that special-purpose external code can be used for this case. When
                    297: used, these functions are always called in a stack-like manner (last obtained,
                    298: first freed), and always for memory blocks of the same size. There is a
                    299: discussion about PCRE's stack usage in the
                    300: .\" HREF
                    301: \fBpcrestack\fP
                    302: .\"
                    303: documentation.
                    304: .P
                    305: The global variable \fBpcre_callout\fP initially contains NULL. It can be set
                    306: by the caller to a "callout" function, which PCRE will then call at specified
                    307: points during a matching operation. Details are given in the
                    308: .\" HREF
                    309: \fBpcrecallout\fP
                    310: .\"
                    311: documentation.
                    312: .
                    313: .
                    314: .\" HTML <a name="newlines"></a>
                    315: .SH NEWLINES
                    316: .rs
                    317: .sp
                    318: PCRE supports five different conventions for indicating line breaks in
                    319: strings: a single CR (carriage return) character, a single LF (linefeed)
                    320: character, the two-character sequence CRLF, any of the three preceding, or any
                    321: Unicode newline sequence. The Unicode newline sequences are the three just
1.1.1.3   misho     322: mentioned, plus the single characters VT (vertical tab, U+000B), FF (form feed,
1.1       misho     323: U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
                    324: (paragraph separator, U+2029).
                    325: .P
                    326: Each of the first three conventions is used by at least one operating system as
                    327: its standard newline sequence. When PCRE is built, a default can be specified.
                    328: The default default is LF, which is the Unix standard. When PCRE is run, the
                    329: default can be overridden, either when a pattern is compiled, or when it is
                    330: matched.
                    331: .P
                    332: At compile time, the newline convention can be specified by the \fIoptions\fP
                    333: argument of \fBpcre_compile()\fP, or it can be specified by special text at the
                    334: start of the pattern itself; this overrides any other settings. See the
                    335: .\" HREF
                    336: \fBpcrepattern\fP
                    337: .\"
                    338: page for details of the special character sequences.
                    339: .P
                    340: In the PCRE documentation the word "newline" is used to mean "the character or
                    341: pair of characters that indicate a line break". The choice of newline
                    342: convention affects the handling of the dot, circumflex, and dollar
                    343: metacharacters, the handling of #-comments in /x mode, and, when CRLF is a
                    344: recognized line ending sequence, the match position advancement for a
                    345: non-anchored pattern. There is more detail about this in the
                    346: .\" HTML <a href="#execoptions">
                    347: .\" </a>
                    348: section on \fBpcre_exec()\fP options
                    349: .\"
                    350: below.
                    351: .P
                    352: The choice of newline convention does not affect the interpretation of
                    353: the \en or \er escape sequences, nor does it affect what \eR matches, which is
                    354: controlled in a similar way, but by separate options.
                    355: .
                    356: .
                    357: .SH MULTITHREADING
                    358: .rs
                    359: .sp
                    360: The PCRE functions can be used in multi-threading applications, with the
                    361: proviso that the memory management functions pointed to by \fBpcre_malloc\fP,
                    362: \fBpcre_free\fP, \fBpcre_stack_malloc\fP, and \fBpcre_stack_free\fP, and the
                    363: callout function pointed to by \fBpcre_callout\fP, are shared by all threads.
                    364: .P
                    365: The compiled form of a regular expression is not altered during matching, so
                    366: the same compiled pattern can safely be used by several threads at once.
                    367: .P
                    368: If the just-in-time optimization feature is being used, it needs separate
                    369: memory stack areas for each thread. See the
                    370: .\" HREF
                    371: \fBpcrejit\fP
                    372: .\"
                    373: documentation for more details.
                    374: .
                    375: .
                    376: .SH "SAVING PRECOMPILED PATTERNS FOR LATER USE"
                    377: .rs
                    378: .sp
                    379: The compiled form of a regular expression can be saved and re-used at a later
                    380: time, possibly by a different program, and even on a host other than the one on
                    381: which it was compiled. Details are given in the
                    382: .\" HREF
                    383: \fBpcreprecompile\fP
                    384: .\"
1.1.1.2   misho     385: documentation, which includes a description of the
                    386: \fBpcre_pattern_to_host_byte_order()\fP function. However, compiling a regular
                    387: expression with one version of PCRE for use with a different version is not
                    388: guaranteed to work and may cause crashes.
1.1       misho     389: .
                    390: .
                    391: .SH "CHECKING BUILD-TIME OPTIONS"
                    392: .rs
                    393: .sp
                    394: .B int pcre_config(int \fIwhat\fP, void *\fIwhere\fP);
                    395: .PP
                    396: The function \fBpcre_config()\fP makes it possible for a PCRE client to
                    397: discover which optional features have been compiled into the PCRE library. The
                    398: .\" HREF
                    399: \fBpcrebuild\fP
                    400: .\"
                    401: documentation has more details about these optional features.
                    402: .P
                    403: The first argument for \fBpcre_config()\fP is an integer, specifying which
                    404: information is required; the second argument is a pointer to a variable into
1.1.1.2   misho     405: which the information is placed. The returned value is zero on success, or the
                    406: negative error code PCRE_ERROR_BADOPTION if the value in the first argument is
                    407: not recognized. The following information is available:
1.1       misho     408: .sp
                    409:   PCRE_CONFIG_UTF8
                    410: .sp
                    411: The output is an integer that is set to one if UTF-8 support is available;
1.1.1.4 ! misho     412: otherwise it is set to zero. This value should normally be given to the 8-bit
        !           413: version of this function, \fBpcre_config()\fP. If it is given to the 16-bit
        !           414: or 32-bit version of this function, the result is PCRE_ERROR_BADOPTION.
1.1.1.2   misho     415: .sp
                    416:   PCRE_CONFIG_UTF16
                    417: .sp
                    418: The output is an integer that is set to one if UTF-16 support is available;
                    419: otherwise it is set to zero. This value should normally be given to the 16-bit
                    420: version of this function, \fBpcre16_config()\fP. If it is given to the 8-bit
1.1.1.4 ! misho     421: or 32-bit version of this function, the result is PCRE_ERROR_BADOPTION.
        !           422: .sp
        !           423:   PCRE_CONFIG_UTF32
        !           424: .sp
        !           425: The output is an integer that is set to one if UTF-32 support is available;
        !           426: otherwise it is set to zero. This value should normally be given to the 32-bit
        !           427: version of this function, \fBpcre32_config()\fP. If it is given to the 8-bit
        !           428: or 16-bit version of this function, the result is PCRE_ERROR_BADOPTION.
1.1       misho     429: .sp
                    430:   PCRE_CONFIG_UNICODE_PROPERTIES
                    431: .sp
                    432: The output is an integer that is set to one if support for Unicode character
                    433: properties is available; otherwise it is set to zero.
                    434: .sp
                    435:   PCRE_CONFIG_JIT
                    436: .sp
                    437: The output is an integer that is set to one if support for just-in-time
                    438: compiling is available; otherwise it is set to zero.
                    439: .sp
1.1.1.2   misho     440:   PCRE_CONFIG_JITTARGET
                    441: .sp
                    442: The output is a pointer to a zero-terminated "const char *" string. If JIT
                    443: support is available, the string contains the name of the architecture for
                    444: which the JIT compiler is configured, for example "x86 32bit (little endian +
                    445: unaligned)". If JIT support is not available, the result is NULL.
                    446: .sp
1.1       misho     447:   PCRE_CONFIG_NEWLINE
                    448: .sp
                    449: The output is an integer whose value specifies the default character sequence
1.1.1.4 ! misho     450: that is recognized as meaning "newline". The values that are supported in
        !           451: ASCII/Unicode environments are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for
        !           452: ANYCRLF, and -1 for ANY. In EBCDIC environments, CR, ANYCRLF, and ANY yield the
        !           453: same values. However, the value for LF is normally 21, though some EBCDIC
        !           454: environments use 37. The corresponding values for CRLF are 3349 and 3365. The
        !           455: default should normally correspond to the standard sequence for your operating
        !           456: system.
1.1       misho     457: .sp
                    458:   PCRE_CONFIG_BSR
                    459: .sp
                    460: The output is an integer whose value indicates what character sequences the \eR
                    461: escape sequence matches by default. A value of 0 means that \eR matches any
                    462: Unicode line ending sequence; a value of 1 means that \eR matches only CR, LF,
                    463: or CRLF. The default can be overridden when a pattern is compiled or matched.
                    464: .sp
                    465:   PCRE_CONFIG_LINK_SIZE
                    466: .sp
                    467: The output is an integer that contains the number of bytes used for internal
1.1.1.2   misho     468: linkage in compiled regular expressions. For the 8-bit library, the value can
                    469: be 2, 3, or 4. For the 16-bit library, the value is either 2 or 4 and is still
1.1.1.4 ! misho     470: a number of bytes. For the 32-bit library, the value is either 2 or 4 and is
        !           471: still a number of bytes. The default value of 2 is sufficient for all but the
        !           472: most massive patterns, since it allows the compiled pattern to be up to 64K in
        !           473: size. Larger values allow larger regular expressions to be compiled, at the
        !           474: expense of slower matching.
1.1       misho     475: .sp
                    476:   PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
                    477: .sp
                    478: The output is an integer that contains the threshold above which the POSIX
                    479: interface uses \fBmalloc()\fP for output vectors. Further details are given in
                    480: the
                    481: .\" HREF
                    482: \fBpcreposix\fP
                    483: .\"
                    484: documentation.
                    485: .sp
                    486:   PCRE_CONFIG_MATCH_LIMIT
                    487: .sp
                    488: The output is a long integer that gives the default limit for the number of
                    489: internal matching function calls in a \fBpcre_exec()\fP execution. Further
                    490: details are given with \fBpcre_exec()\fP below.
                    491: .sp
                    492:   PCRE_CONFIG_MATCH_LIMIT_RECURSION
                    493: .sp
                    494: The output is a long integer that gives the default limit for the depth of
                    495: recursion when calling the internal matching function in a \fBpcre_exec()\fP
                    496: execution. Further details are given with \fBpcre_exec()\fP below.
                    497: .sp
                    498:   PCRE_CONFIG_STACKRECURSE
                    499: .sp
                    500: The output is an integer that is set to one if internal recursion when running
                    501: \fBpcre_exec()\fP is implemented by recursive function calls that use the stack
                    502: to remember their state. This is the usual way that PCRE is compiled. The
                    503: output is zero if PCRE was compiled to use blocks of data on the heap instead
                    504: of recursive function calls. In this case, \fBpcre_stack_malloc\fP and
                    505: \fBpcre_stack_free\fP are called to manage memory blocks on the heap, thus
                    506: avoiding the use of the stack.
                    507: .
                    508: .
                    509: .SH "COMPILING A PATTERN"
                    510: .rs
                    511: .sp
                    512: .B pcre *pcre_compile(const char *\fIpattern\fP, int \fIoptions\fP,
                    513: .ti +5n
                    514: .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
                    515: .ti +5n
                    516: .B const unsigned char *\fItableptr\fP);
                    517: .sp
                    518: .B pcre *pcre_compile2(const char *\fIpattern\fP, int \fIoptions\fP,
                    519: .ti +5n
                    520: .B int *\fIerrorcodeptr\fP,
                    521: .ti +5n
                    522: .B const char **\fIerrptr\fP, int *\fIerroffset\fP,
                    523: .ti +5n
                    524: .B const unsigned char *\fItableptr\fP);
                    525: .P
                    526: Either of the functions \fBpcre_compile()\fP or \fBpcre_compile2()\fP can be
                    527: called to compile a pattern into an internal form. The only difference between
                    528: the two interfaces is that \fBpcre_compile2()\fP has an additional argument,
                    529: \fIerrorcodeptr\fP, via which a numerical error code can be returned. To avoid
                    530: too much repetition, we refer just to \fBpcre_compile()\fP below, but the
                    531: information applies equally to \fBpcre_compile2()\fP.
                    532: .P
                    533: The pattern is a C string terminated by a binary zero, and is passed in the
                    534: \fIpattern\fP argument. A pointer to a single block of memory that is obtained
                    535: via \fBpcre_malloc\fP is returned. This contains the compiled code and related
                    536: data. The \fBpcre\fP type is defined for the returned block; this is a typedef
                    537: for a structure whose contents are not externally defined. It is up to the
                    538: caller to free the memory (via \fBpcre_free\fP) when it is no longer required.
                    539: .P
                    540: Although the compiled code of a PCRE regex is relocatable, that is, it does not
                    541: depend on memory location, the complete \fBpcre\fP data block is not
                    542: fully relocatable, because it may contain a copy of the \fItableptr\fP
                    543: argument, which is an address (see below).
                    544: .P
                    545: The \fIoptions\fP argument contains various bit settings that affect the
                    546: compilation. It should be zero if no options are required. The available
                    547: options are described below. Some of them (in particular, those that are
                    548: compatible with Perl, but some others as well) can also be set and unset from
                    549: within the pattern (see the detailed description in the
                    550: .\" HREF
                    551: \fBpcrepattern\fP
                    552: .\"
                    553: documentation). For those options that can be different in different parts of
                    554: the pattern, the contents of the \fIoptions\fP argument specifies their
                    555: settings at the start of compilation and execution. The PCRE_ANCHORED,
                    556: PCRE_BSR_\fIxxx\fP, PCRE_NEWLINE_\fIxxx\fP, PCRE_NO_UTF8_CHECK, and
1.1.1.3   misho     557: PCRE_NO_START_OPTIMIZE options can be set at the time of matching as well as at
1.1       misho     558: compile time.
                    559: .P
                    560: If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
                    561: Otherwise, if compilation of a pattern fails, \fBpcre_compile()\fP returns
                    562: NULL, and sets the variable pointed to by \fIerrptr\fP to point to a textual
                    563: error message. This is a static string that is part of the library. You must
                    564: not try to free it. Normally, the offset from the start of the pattern to the
1.1.1.4 ! misho     565: data unit that was being processed when the error was discovered is placed in
        !           566: the variable pointed to by \fIerroffset\fP, which must not be NULL (if it is,
        !           567: an immediate error is given). However, for an invalid UTF-8 or UTF-16 string,
        !           568: the offset is that of the first data unit of the failing character.
1.1       misho     569: .P
1.1.1.2   misho     570: Some errors are not detected until the whole pattern has been scanned; in these
                    571: cases, the offset passed back is the length of the pattern. Note that the
1.1.1.4 ! misho     572: offset is in data units, not characters, even in a UTF mode. It may sometimes
        !           573: point into the middle of a UTF-8 or UTF-16 character.
1.1       misho     574: .P
                    575: If \fBpcre_compile2()\fP is used instead of \fBpcre_compile()\fP, and the
                    576: \fIerrorcodeptr\fP argument is not NULL, a non-zero error code number is
                    577: returned via this argument in the event of an error. This is in addition to the
                    578: textual error message. Error codes and messages are listed below.
                    579: .P
                    580: If the final argument, \fItableptr\fP, is NULL, PCRE uses a default set of
                    581: character tables that are built when PCRE is compiled, using the default C
                    582: locale. Otherwise, \fItableptr\fP must be an address that is the result of a
                    583: call to \fBpcre_maketables()\fP. This value is stored with the compiled
                    584: pattern, and used again by \fBpcre_exec()\fP, unless another table pointer is
                    585: passed to it. For more discussion, see the section on locale support below.
                    586: .P
                    587: This code fragment shows a typical straightforward call to \fBpcre_compile()\fP:
                    588: .sp
                    589:   pcre *re;
                    590:   const char *error;
                    591:   int erroffset;
                    592:   re = pcre_compile(
                    593:     "^A.*Z",          /* the pattern */
                    594:     0,                /* default options */
                    595:     &error,           /* for error message */
                    596:     &erroffset,       /* for error offset */
                    597:     NULL);            /* use default character tables */
                    598: .sp
                    599: The following names for option bits are defined in the \fBpcre.h\fP header
                    600: file:
                    601: .sp
                    602:   PCRE_ANCHORED
                    603: .sp
                    604: If this bit is set, the pattern is forced to be "anchored", that is, it is
                    605: constrained to match only at the first matching point in the string that is
                    606: being searched (the "subject string"). This effect can also be achieved by
                    607: appropriate constructs in the pattern itself, which is the only way to do it in
                    608: Perl.
                    609: .sp
                    610:   PCRE_AUTO_CALLOUT
                    611: .sp
                    612: If this bit is set, \fBpcre_compile()\fP automatically inserts callout items,
                    613: all with number 255, before each pattern item. For discussion of the callout
                    614: facility, see the
                    615: .\" HREF
                    616: \fBpcrecallout\fP
                    617: .\"
                    618: documentation.
                    619: .sp
                    620:   PCRE_BSR_ANYCRLF
                    621:   PCRE_BSR_UNICODE
                    622: .sp
                    623: These options (which are mutually exclusive) control what the \eR escape
                    624: sequence matches. The choice is either to match only CR, LF, or CRLF, or to
                    625: match any Unicode newline sequence. The default is specified when PCRE is
                    626: built. It can be overridden from within the pattern, or by setting an option
                    627: when a compiled pattern is matched.
                    628: .sp
                    629:   PCRE_CASELESS
                    630: .sp
                    631: If this bit is set, letters in the pattern match both upper and lower case
                    632: letters. It is equivalent to Perl's /i option, and it can be changed within a
                    633: pattern by a (?i) option setting. In UTF-8 mode, PCRE always understands the
                    634: concept of case for characters whose values are less than 128, so caseless
                    635: matching is always possible. For characters with higher values, the concept of
                    636: case is supported if PCRE is compiled with Unicode property support, but not
                    637: otherwise. If you want to use caseless matching for characters 128 and above,
                    638: you must ensure that PCRE is compiled with Unicode property support as well as
                    639: with UTF-8 support.
                    640: .sp
                    641:   PCRE_DOLLAR_ENDONLY
                    642: .sp
                    643: If this bit is set, a dollar metacharacter in the pattern matches only at the
                    644: end of the subject string. Without this option, a dollar also matches
                    645: immediately before a newline at the end of the string (but not before any other
                    646: newlines). The PCRE_DOLLAR_ENDONLY option is ignored if PCRE_MULTILINE is set.
                    647: There is no equivalent to this option in Perl, and no way to set it within a
                    648: pattern.
                    649: .sp
                    650:   PCRE_DOTALL
                    651: .sp
                    652: If this bit is set, a dot metacharacter in the pattern matches a character of
                    653: any value, including one that indicates a newline. However, it only ever
                    654: matches one character, even if newlines are coded as CRLF. Without this option,
                    655: a dot does not match when the current position is at a newline. This option is
                    656: equivalent to Perl's /s option, and it can be changed within a pattern by a
                    657: (?s) option setting. A negative class such as [^a] always matches newline
                    658: characters, independent of the setting of this option.
                    659: .sp
                    660:   PCRE_DUPNAMES
                    661: .sp
                    662: If this bit is set, names used to identify capturing subpatterns need not be
                    663: unique. This can be helpful for certain types of pattern when it is known that
                    664: only one instance of the named subpattern can ever be matched. There are more
                    665: details of named subpatterns below; see also the
                    666: .\" HREF
                    667: \fBpcrepattern\fP
                    668: .\"
                    669: documentation.
                    670: .sp
                    671:   PCRE_EXTENDED
                    672: .sp
1.1.1.3   misho     673: If this bit is set, white space data characters in the pattern are totally
                    674: ignored except when escaped or inside a character class. White space does not
1.1       misho     675: include the VT character (code 11). In addition, characters between an
                    676: unescaped # outside a character class and the next newline, inclusive, are also
                    677: ignored. This is equivalent to Perl's /x option, and it can be changed within a
                    678: pattern by a (?x) option setting.
                    679: .P
                    680: Which characters are interpreted as newlines is controlled by the options
                    681: passed to \fBpcre_compile()\fP or by a special sequence at the start of the
                    682: pattern, as described in the section entitled
                    683: .\" HTML <a href="pcrepattern.html#newlines">
                    684: .\" </a>
                    685: "Newline conventions"
                    686: .\"
                    687: in the \fBpcrepattern\fP documentation. Note that the end of this type of
                    688: comment is a literal newline sequence in the pattern; escape sequences that
                    689: happen to represent a newline do not count.
                    690: .P
                    691: This option makes it possible to include comments inside complicated patterns.
1.1.1.3   misho     692: Note, however, that this applies only to data characters. White space characters
1.1       misho     693: may never appear within special character sequences in a pattern, for example
                    694: within the sequence (?( that introduces a conditional subpattern.
                    695: .sp
                    696:   PCRE_EXTRA
                    697: .sp
                    698: This option was invented in order to turn on additional functionality of PCRE
                    699: that is incompatible with Perl, but it is currently of very little use. When
                    700: set, any backslash in a pattern that is followed by a letter that has no
                    701: special meaning causes an error, thus reserving these combinations for future
                    702: expansion. By default, as in Perl, a backslash followed by a letter with no
                    703: special meaning is treated as a literal. (Perl can, however, be persuaded to
                    704: give an error for this, by running it with the -w option.) There are at present
                    705: no other features controlled by this option. It can also be set by a (?X)
                    706: option setting within a pattern.
                    707: .sp
                    708:   PCRE_FIRSTLINE
                    709: .sp
                    710: If this option is set, an unanchored pattern is required to match before or at
                    711: the first newline in the subject string, though the matched text may continue
                    712: over the newline.
                    713: .sp
                    714:   PCRE_JAVASCRIPT_COMPAT
                    715: .sp
                    716: If this option is set, PCRE's behaviour is changed in some ways so that it is
                    717: compatible with JavaScript rather than Perl. The changes are as follows:
                    718: .P
                    719: (1) A lone closing square bracket in a pattern causes a compile-time error,
                    720: because this is illegal in JavaScript (by default it is treated as a data
                    721: character). Thus, the pattern AB]CD becomes illegal when this option is set.
                    722: .P
                    723: (2) At run time, a back reference to an unset subpattern group matches an empty
                    724: string (by default this causes the current matching alternative to fail). A
                    725: pattern such as (\e1)(a) succeeds when this option is set (assuming it can find
                    726: an "a" in the subject), whereas it fails by default, for Perl compatibility.
                    727: .P
                    728: (3) \eU matches an upper case "U" character; by default \eU causes a compile
                    729: time error (Perl uses \eU to upper case subsequent characters).
                    730: .P
                    731: (4) \eu matches a lower case "u" character unless it is followed by four
                    732: hexadecimal digits, in which case the hexadecimal number defines the code point
                    733: to match. By default, \eu causes a compile time error (Perl uses it to upper
                    734: case the following character).
                    735: .P
                    736: (5) \ex matches a lower case "x" character unless it is followed by two
                    737: hexadecimal digits, in which case the hexadecimal number defines the code point
                    738: to match. By default, as in Perl, a hexadecimal number is always expected after
                    739: \ex, but it may have zero, one, or two digits (so, for example, \exz matches a
                    740: binary zero character followed by z).
                    741: .sp
                    742:   PCRE_MULTILINE
                    743: .sp
1.1.1.4 ! misho     744: By default, for the purposes of matching "start of line" and "end of line",
        !           745: PCRE treats the subject string as consisting of a single line of characters,
        !           746: even if it actually contains newlines. The "start of line" metacharacter (^)
        !           747: matches only at the start of the string, and the "end of line" metacharacter
        !           748: ($) matches only at the end of the string, or before a terminating newline
        !           749: (except when PCRE_DOLLAR_ENDONLY is set). Note, however, that unless
        !           750: PCRE_DOTALL is set, the "any character" metacharacter (.) does not match at a
        !           751: newline. This behaviour (for ^, $, and dot) is the same as Perl.
1.1       misho     752: .P
                    753: When PCRE_MULTILINE it is set, the "start of line" and "end of line" constructs
                    754: match immediately following or immediately before internal newlines in the
                    755: subject string, respectively, as well as at the very start and end. This is
                    756: equivalent to Perl's /m option, and it can be changed within a pattern by a
                    757: (?m) option setting. If there are no newlines in a subject string, or no
                    758: occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.
                    759: .sp
1.1.1.4 ! misho     760:   PCRE_NEVER_UTF
        !           761: .sp
        !           762: This option locks out interpretation of the pattern as UTF-8 (or UTF-16 or
        !           763: UTF-32 in the 16-bit and 32-bit libraries). In particular, it prevents the
        !           764: creator of the pattern from switching to UTF interpretation by starting the
        !           765: pattern with (*UTF). This may be useful in applications that process patterns
        !           766: from external sources. The combination of PCRE_UTF8 and PCRE_NEVER_UTF also
        !           767: causes an error.
        !           768: .sp
1.1       misho     769:   PCRE_NEWLINE_CR
                    770:   PCRE_NEWLINE_LF
                    771:   PCRE_NEWLINE_CRLF
                    772:   PCRE_NEWLINE_ANYCRLF
                    773:   PCRE_NEWLINE_ANY
                    774: .sp
                    775: These options override the default newline definition that was chosen when PCRE
                    776: was built. Setting the first or the second specifies that a newline is
                    777: indicated by a single character (CR or LF, respectively). Setting
                    778: PCRE_NEWLINE_CRLF specifies that a newline is indicated by the two-character
                    779: CRLF sequence. Setting PCRE_NEWLINE_ANYCRLF specifies that any of the three
                    780: preceding sequences should be recognized. Setting PCRE_NEWLINE_ANY specifies
1.1.1.4 ! misho     781: that any Unicode newline sequence should be recognized.
        !           782: .P
        !           783: In an ASCII/Unicode environment, the Unicode newline sequences are the three
        !           784: just mentioned, plus the single characters VT (vertical tab, U+000B), FF (form
        !           785: feed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
        !           786: (paragraph separator, U+2029). For the 8-bit library, the last two are
        !           787: recognized only in UTF-8 mode.
        !           788: .P
        !           789: When PCRE is compiled to run in an EBCDIC (mainframe) environment, the code for
        !           790: CR is 0x0d, the same as ASCII. However, the character code for LF is normally
        !           791: 0x15, though in some EBCDIC environments 0x25 is used. Whichever of these is
        !           792: not LF is made to correspond to Unicode's NEL character. EBCDIC codes are all
        !           793: less than 256. For more details, see the
        !           794: .\" HREF
        !           795: \fBpcrebuild\fP
        !           796: .\"
        !           797: documentation.
1.1       misho     798: .P
                    799: The newline setting in the options word uses three bits that are treated
                    800: as a number, giving eight possibilities. Currently only six are used (default
                    801: plus the five values above). This means that if you set more than one newline
                    802: option, the combination may or may not be sensible. For example,
                    803: PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but
                    804: other combinations may yield unused numbers and cause an error.
                    805: .P
                    806: The only time that a line break in a pattern is specially recognized when
1.1.1.3   misho     807: compiling is when PCRE_EXTENDED is set. CR and LF are white space characters,
1.1       misho     808: and so are ignored in this mode. Also, an unescaped # outside a character class
                    809: indicates a comment that lasts until after the next line break sequence. In
                    810: other circumstances, line break sequences in patterns are treated as literal
                    811: data.
                    812: .P
                    813: The newline option that is set at compile time becomes the default that is used
                    814: for \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, but it can be overridden.
                    815: .sp
                    816:   PCRE_NO_AUTO_CAPTURE
                    817: .sp
                    818: If this option is set, it disables the use of numbered capturing parentheses in
                    819: the pattern. Any opening parenthesis that is not followed by ? behaves as if it
                    820: were followed by ?: but named parentheses can still be used for capturing (and
                    821: they acquire numbers in the usual way). There is no equivalent of this option
                    822: in Perl.
                    823: .sp
1.1.1.4 ! misho     824:   PCRE_NO_START_OPTIMIZE
1.1       misho     825: .sp
                    826: This is an option that acts at matching time; that is, it is really an option
                    827: for \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP. If it is set at compile time,
1.1.1.4 ! misho     828: it is remembered with the compiled pattern and assumed at matching time. This
        !           829: is necessary if you want to use JIT execution, because the JIT compiler needs
        !           830: to know whether or not this option is set. For details see the discussion of
        !           831: PCRE_NO_START_OPTIMIZE
1.1       misho     832: .\" HTML <a href="#execoptions">
                    833: .\" </a>
                    834: below.
                    835: .\"
                    836: .sp
                    837:   PCRE_UCP
                    838: .sp
                    839: This option changes the way PCRE processes \eB, \eb, \eD, \ed, \eS, \es, \eW,
                    840: \ew, and some of the POSIX character classes. By default, only ASCII characters
                    841: are recognized, but if PCRE_UCP is set, Unicode properties are used instead to
                    842: classify characters. More details are given in the section on
                    843: .\" HTML <a href="pcre.html#genericchartypes">
                    844: .\" </a>
                    845: generic character types
                    846: .\"
                    847: in the
                    848: .\" HREF
                    849: \fBpcrepattern\fP
                    850: .\"
                    851: page. If you set PCRE_UCP, matching one of the items it affects takes much
                    852: longer. The option is available only if PCRE has been compiled with Unicode
                    853: property support.
                    854: .sp
                    855:   PCRE_UNGREEDY
                    856: .sp
                    857: This option inverts the "greediness" of the quantifiers so that they are not
                    858: greedy by default, but become greedy if followed by "?". It is not compatible
                    859: with Perl. It can also be set by a (?U) option setting within the pattern.
                    860: .sp
                    861:   PCRE_UTF8
                    862: .sp
                    863: This option causes PCRE to regard both the pattern and the subject as strings
1.1.1.2   misho     864: of UTF-8 characters instead of single-byte strings. However, it is available
                    865: only when PCRE is built to include UTF support. If not, the use of this option
                    866: provokes an error. Details of how this option changes the behaviour of PCRE are
                    867: given in the
1.1       misho     868: .\" HREF
                    869: \fBpcreunicode\fP
                    870: .\"
                    871: page.
                    872: .sp
                    873:   PCRE_NO_UTF8_CHECK
                    874: .sp
1.1.1.4 ! misho     875: When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is
        !           876: automatically checked. There is a discussion about the
1.1.1.2   misho     877: .\" HTML <a href="pcreunicode.html#utf8strings">
1.1       misho     878: .\" </a>
                    879: validity of UTF-8 strings
                    880: .\"
1.1.1.2   misho     881: in the
1.1       misho     882: .\" HREF
1.1.1.2   misho     883: \fBpcreunicode\fP
1.1       misho     884: .\"
1.1.1.2   misho     885: page. If an invalid UTF-8 sequence is found, \fBpcre_compile()\fP returns an
                    886: error. If you already know that your pattern is valid, and you want to skip
                    887: this check for performance reasons, you can set the PCRE_NO_UTF8_CHECK option.
                    888: When it is set, the effect of passing an invalid UTF-8 string as a pattern is
                    889: undefined. It may cause your program to crash. Note that this option can also
                    890: be passed to \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, to suppress the
1.1.1.4 ! misho     891: validity checking of subject strings only. If the same string is being matched
        !           892: many times, the option can be safely set for the second and subsequent
        !           893: matchings to improve performance.
1.1       misho     894: .
                    895: .
                    896: .SH "COMPILATION ERROR CODES"
                    897: .rs
                    898: .sp
                    899: The following table lists the error codes than may be returned by
                    900: \fBpcre_compile2()\fP, along with the error messages that may be returned by
1.1.1.2   misho     901: both compiling functions. Note that error messages are always 8-bit ASCII
1.1.1.4 ! misho     902: strings, even in 16-bit or 32-bit mode. As PCRE has developed, some error codes
        !           903: have fallen out of use. To avoid confusion, they have not been re-used.
1.1       misho     904: .sp
                    905:    0  no error
                    906:    1  \e at end of pattern
                    907:    2  \ec at end of pattern
                    908:    3  unrecognized character follows \e
                    909:    4  numbers out of order in {} quantifier
                    910:    5  number too big in {} quantifier
                    911:    6  missing terminating ] for character class
                    912:    7  invalid escape sequence in character class
                    913:    8  range out of order in character class
                    914:    9  nothing to repeat
                    915:   10  [this code is not in use]
                    916:   11  internal error: unexpected repeat
                    917:   12  unrecognized character after (? or (?-
                    918:   13  POSIX named classes are supported only within a class
                    919:   14  missing )
                    920:   15  reference to non-existent subpattern
                    921:   16  erroffset passed as NULL
                    922:   17  unknown option bit(s) set
                    923:   18  missing ) after comment
                    924:   19  [this code is not in use]
                    925:   20  regular expression is too large
                    926:   21  failed to get memory
                    927:   22  unmatched parentheses
                    928:   23  internal error: code overflow
                    929:   24  unrecognized character after (?<
                    930:   25  lookbehind assertion is not fixed length
                    931:   26  malformed number or name after (?(
                    932:   27  conditional group contains more than two branches
                    933:   28  assertion expected after (?(
                    934:   29  (?R or (?[+-]digits must be followed by )
                    935:   30  unknown POSIX class name
                    936:   31  POSIX collating elements are not supported
1.1.1.2   misho     937:   32  this version of PCRE is compiled without UTF support
1.1       misho     938:   33  [this code is not in use]
                    939:   34  character value in \ex{...} sequence is too large
                    940:   35  invalid condition (?(0)
                    941:   36  \eC not allowed in lookbehind assertion
                    942:   37  PCRE does not support \eL, \el, \eN{name}, \eU, or \eu
                    943:   38  number after (?C is > 255
                    944:   39  closing ) for (?C expected
                    945:   40  recursive call could loop indefinitely
                    946:   41  unrecognized character after (?P
                    947:   42  syntax error in subpattern name (missing terminator)
                    948:   43  two named subpatterns have the same name
1.1.1.2   misho     949:   44  invalid UTF-8 string (specifically UTF-8)
1.1       misho     950:   45  support for \eP, \ep, and \eX has not been compiled
                    951:   46  malformed \eP or \ep sequence
                    952:   47  unknown property name after \eP or \ep
                    953:   48  subpattern name is too long (maximum 32 characters)
                    954:   49  too many named subpatterns (maximum 10000)
                    955:   50  [this code is not in use]
1.1.1.2   misho     956:   51  octal value is greater than \e377 in 8-bit non-UTF-8 mode
1.1       misho     957:   52  internal error: overran compiling workspace
                    958:   53  internal error: previously-checked referenced subpattern
                    959:         not found
                    960:   54  DEFINE group contains more than one branch
                    961:   55  repeating a DEFINE group is not allowed
                    962:   56  inconsistent NEWLINE options
                    963:   57  \eg is not followed by a braced, angle-bracketed, or quoted
                    964:         name/number or by a plain number
                    965:   58  a numbered reference must not be zero
                    966:   59  an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
1.1.1.4 ! misho     967:   60  (*VERB) not recognized or malformed
1.1       misho     968:   61  number is too big
                    969:   62  subpattern name expected
                    970:   63  digit expected after (?+
                    971:   64  ] is an invalid data character in JavaScript compatibility mode
                    972:   65  different names for subpatterns of the same number are
                    973:         not allowed
                    974:   66  (*MARK) must have an argument
1.1.1.2   misho     975:   67  this version of PCRE is not compiled with Unicode property
                    976:         support
1.1       misho     977:   68  \ec must be followed by an ASCII character
                    978:   69  \ek is not followed by a braced, angle-bracketed, or quoted name
1.1.1.2   misho     979:   70  internal error: unknown opcode in find_fixedlength()
                    980:   71  \eN is not supported in a class
                    981:   72  too many forward references
                    982:   73  disallowed Unicode code point (>= 0xd800 && <= 0xdfff)
                    983:   74  invalid UTF-16 string (specifically UTF-16)
1.1.1.3   misho     984:   75  name is too long in (*MARK), (*PRUNE), (*SKIP), or (*THEN)
                    985:   76  character value in \eu.... sequence is too large
1.1.1.4 ! misho     986:   77  invalid UTF-32 string (specifically UTF-32)
1.1       misho     987: .sp
                    988: The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may
                    989: be used if the limits were changed when PCRE was built.
                    990: .
                    991: .
                    992: .\" HTML <a name="studyingapattern"></a>
                    993: .SH "STUDYING A PATTERN"
                    994: .rs
                    995: .sp
                    996: .B pcre_extra *pcre_study(const pcre *\fIcode\fP, int \fIoptions\fP
                    997: .ti +5n
                    998: .B const char **\fIerrptr\fP);
                    999: .PP
                   1000: If a compiled pattern is going to be used several times, it is worth spending
                   1001: more time analyzing it in order to speed up the time taken for matching. The
                   1002: function \fBpcre_study()\fP takes a pointer to a compiled pattern as its first
                   1003: argument. If studying the pattern produces additional information that will
                   1004: help speed up matching, \fBpcre_study()\fP returns a pointer to a
                   1005: \fBpcre_extra\fP block, in which the \fIstudy_data\fP field points to the
                   1006: results of the study.
                   1007: .P
                   1008: The returned value from \fBpcre_study()\fP can be passed directly to
                   1009: \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP. However, a \fBpcre_extra\fP block
                   1010: also contains other fields that can be set by the caller before the block is
                   1011: passed; these are described
                   1012: .\" HTML <a href="#extradata">
                   1013: .\" </a>
                   1014: below
                   1015: .\"
                   1016: in the section on matching a pattern.
                   1017: .P
                   1018: If studying the pattern does not produce any useful information,
1.1.1.4 ! misho    1019: \fBpcre_study()\fP returns NULL by default. In that circumstance, if the
        !          1020: calling program wants to pass any of the other fields to \fBpcre_exec()\fP or
        !          1021: \fBpcre_dfa_exec()\fP, it must set up its own \fBpcre_extra\fP block. However,
        !          1022: if \fBpcre_study()\fP is called with the PCRE_STUDY_EXTRA_NEEDED option, it
        !          1023: returns a \fBpcre_extra\fP block even if studying did not find any additional
        !          1024: information. It may still return NULL, however, if an error occurs in
        !          1025: \fBpcre_study()\fP.
1.1       misho    1026: .P
1.1.1.3   misho    1027: The second argument of \fBpcre_study()\fP contains option bits. There are three
1.1.1.4 ! misho    1028: further options in addition to PCRE_STUDY_EXTRA_NEEDED:
1.1.1.3   misho    1029: .sp
                   1030:   PCRE_STUDY_JIT_COMPILE
                   1031:   PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
                   1032:   PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
                   1033: .sp
                   1034: If any of these are set, and the just-in-time compiler is available, the
                   1035: pattern is further compiled into machine code that executes much faster than
                   1036: the \fBpcre_exec()\fP interpretive matching function. If the just-in-time
1.1.1.4 ! misho    1037: compiler is not available, these options are ignored. All undefined bits in the
1.1.1.3   misho    1038: \fIoptions\fP argument must be zero.
1.1       misho    1039: .P
                   1040: JIT compilation is a heavyweight optimization. It can take some time for
                   1041: patterns to be analyzed, and for one-off matches and simple patterns the
                   1042: benefit of faster execution might be offset by a much slower study time.
                   1043: Not all patterns can be optimized by the JIT compiler. For those that cannot be
                   1044: handled, matching automatically falls back to the \fBpcre_exec()\fP
                   1045: interpreter. For more details, see the
                   1046: .\" HREF
                   1047: \fBpcrejit\fP
                   1048: .\"
                   1049: documentation.
                   1050: .P
                   1051: The third argument for \fBpcre_study()\fP is a pointer for an error message. If
                   1052: studying succeeds (even if no data is returned), the variable it points to is
                   1053: set to NULL. Otherwise it is set to point to a textual error message. This is a
                   1054: static string that is part of the library. You must not try to free it. You
                   1055: should test the error pointer for NULL after calling \fBpcre_study()\fP, to be
                   1056: sure that it has run successfully.
                   1057: .P
                   1058: When you are finished with a pattern, you can free the memory used for the
                   1059: study data by calling \fBpcre_free_study()\fP. This function was added to the
                   1060: API for release 8.20. For earlier versions, the memory could be freed with
                   1061: \fBpcre_free()\fP, just like the pattern itself. This will still work in cases
1.1.1.3   misho    1062: where JIT optimization is not used, but it is advisable to change to the new
                   1063: function when convenient.
1.1       misho    1064: .P
                   1065: This is a typical way in which \fBpcre_study\fP() is used (except that in a
                   1066: real application there should be tests for errors):
                   1067: .sp
                   1068:   int rc;
                   1069:   pcre *re;
                   1070:   pcre_extra *sd;
                   1071:   re = pcre_compile("pattern", 0, &error, &erroroffset, NULL);
                   1072:   sd = pcre_study(
                   1073:     re,             /* result of pcre_compile() */
                   1074:     0,              /* no options */
                   1075:     &error);        /* set to NULL or points to a message */
                   1076:   rc = pcre_exec(   /* see below for details of pcre_exec() options */
                   1077:     re, sd, "subject", 7, 0, 0, ovector, 30);
                   1078:   ...
                   1079:   pcre_free_study(sd);
                   1080:   pcre_free(re);
                   1081: .sp
                   1082: Studying a pattern does two things: first, a lower bound for the length of
                   1083: subject string that is needed to match the pattern is computed. This does not
                   1084: mean that there are any strings of that length that match, but it does
1.1.1.4 ! misho    1085: guarantee that no shorter strings match. The value is used to avoid wasting
        !          1086: time by trying to match strings that are shorter than the lower bound. You can
        !          1087: find out the value in a calling program via the \fBpcre_fullinfo()\fP function.
1.1       misho    1088: .P
                   1089: Studying a pattern is also useful for non-anchored patterns that do not have a
                   1090: single fixed starting character. A bitmap of possible starting bytes is
                   1091: created. This speeds up finding a position in the subject at which to start
1.1.1.4 ! misho    1092: matching. (In 16-bit mode, the bitmap is used for 16-bit values less than 256.
        !          1093: In 32-bit mode, the bitmap is used for 32-bit values less than 256.)
1.1       misho    1094: .P
                   1095: These two optimizations apply to both \fBpcre_exec()\fP and
1.1.1.3   misho    1096: \fBpcre_dfa_exec()\fP, and the information is also used by the JIT compiler.
1.1.1.4 ! misho    1097: The optimizations can be disabled by setting the PCRE_NO_START_OPTIMIZE option.
        !          1098: You might want to do this if your pattern contains callouts or (*MARK) and you
        !          1099: want to make use of these facilities in cases where matching fails.
        !          1100: .P
        !          1101: PCRE_NO_START_OPTIMIZE can be specified at either compile time or execution
        !          1102: time. However, if PCRE_NO_START_OPTIMIZE is passed to \fBpcre_exec()\fP, (that
        !          1103: is, after any JIT compilation has happened) JIT execution is disabled. For JIT
        !          1104: execution to work with PCRE_NO_START_OPTIMIZE, the option must be set at
        !          1105: compile time.
        !          1106: .P
        !          1107: There is a longer discussion of PCRE_NO_START_OPTIMIZE
1.1       misho    1108: .\" HTML <a href="#execoptions">
                   1109: .\" </a>
                   1110: below.
                   1111: .\"
                   1112: .
                   1113: .
                   1114: .\" HTML <a name="localesupport"></a>
                   1115: .SH "LOCALE SUPPORT"
                   1116: .rs
                   1117: .sp
                   1118: PCRE handles caseless matching, and determines whether characters are letters,
                   1119: digits, or whatever, by reference to a set of tables, indexed by character
1.1.1.2   misho    1120: value. When running in UTF-8 mode, this applies only to characters
                   1121: with codes less than 128. By default, higher-valued codes never match escapes
                   1122: such as \ew or \ed, but they can be tested with \ep if PCRE is built with
                   1123: Unicode character property support. Alternatively, the PCRE_UCP option can be
                   1124: set at compile time; this causes \ew and friends to use Unicode property
                   1125: support instead of built-in tables. The use of locales with Unicode is
                   1126: discouraged. If you are handling characters with codes greater than 128, you
                   1127: should either use UTF-8 and Unicode, or use locales, but not try to mix the
                   1128: two.
1.1       misho    1129: .P
                   1130: PCRE contains an internal set of tables that are used when the final argument
                   1131: of \fBpcre_compile()\fP is NULL. These are sufficient for many applications.
                   1132: Normally, the internal tables recognize only ASCII characters. However, when
                   1133: PCRE is built, it is possible to cause the internal tables to be rebuilt in the
                   1134: default "C" locale of the local system, which may cause them to be different.
                   1135: .P
                   1136: The internal tables can always be overridden by tables supplied by the
                   1137: application that calls PCRE. These may be created in a different locale from
                   1138: the default. As more and more applications change to using Unicode, the need
                   1139: for this locale support is expected to die away.
                   1140: .P
                   1141: External tables are built by calling the \fBpcre_maketables()\fP function,
                   1142: which has no arguments, in the relevant locale. The result can then be passed
                   1143: to \fBpcre_compile()\fP or \fBpcre_exec()\fP as often as necessary. For
                   1144: example, to build and use tables that are appropriate for the French locale
                   1145: (where accented characters with values greater than 128 are treated as letters),
                   1146: the following code could be used:
                   1147: .sp
                   1148:   setlocale(LC_CTYPE, "fr_FR");
                   1149:   tables = pcre_maketables();
                   1150:   re = pcre_compile(..., tables);
                   1151: .sp
                   1152: The locale name "fr_FR" is used on Linux and other Unix-like systems; if you
                   1153: are using Windows, the name for the French locale is "french".
                   1154: .P
                   1155: When \fBpcre_maketables()\fP runs, the tables are built in memory that is
                   1156: obtained via \fBpcre_malloc\fP. It is the caller's responsibility to ensure
                   1157: that the memory containing the tables remains available for as long as it is
                   1158: needed.
                   1159: .P
                   1160: The pointer that is passed to \fBpcre_compile()\fP is saved with the compiled
                   1161: pattern, and the same tables are used via this pointer by \fBpcre_study()\fP
                   1162: and normally also by \fBpcre_exec()\fP. Thus, by default, for any single
                   1163: pattern, compilation, studying and matching all happen in the same locale, but
                   1164: different patterns can be compiled in different locales.
                   1165: .P
                   1166: It is possible to pass a table pointer or NULL (indicating the use of the
                   1167: internal tables) to \fBpcre_exec()\fP. Although not intended for this purpose,
                   1168: this facility could be used to match a pattern in a different locale from the
                   1169: one in which it was compiled. Passing table pointers at run time is discussed
                   1170: below in the section on matching a pattern.
                   1171: .
                   1172: .
                   1173: .\" HTML <a name="infoaboutpattern"></a>
                   1174: .SH "INFORMATION ABOUT A PATTERN"
                   1175: .rs
                   1176: .sp
                   1177: .B int pcre_fullinfo(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
                   1178: .ti +5n
                   1179: .B int \fIwhat\fP, void *\fIwhere\fP);
                   1180: .PP
                   1181: The \fBpcre_fullinfo()\fP function returns information about a compiled
1.1.1.2   misho    1182: pattern. It replaces the \fBpcre_info()\fP function, which was removed from the
                   1183: library at version 8.30, after more than 10 years of obsolescence.
1.1       misho    1184: .P
                   1185: The first argument for \fBpcre_fullinfo()\fP is a pointer to the compiled
                   1186: pattern. The second argument is the result of \fBpcre_study()\fP, or NULL if
                   1187: the pattern was not studied. The third argument specifies which piece of
                   1188: information is required, and the fourth argument is a pointer to a variable
                   1189: to receive the data. The yield of the function is zero for success, or one of
                   1190: the following negative numbers:
                   1191: .sp
1.1.1.2   misho    1192:   PCRE_ERROR_NULL           the argument \fIcode\fP was NULL
                   1193:                             the argument \fIwhere\fP was NULL
                   1194:   PCRE_ERROR_BADMAGIC       the "magic number" was not found
                   1195:   PCRE_ERROR_BADENDIANNESS  the pattern was compiled with different
                   1196:                             endianness
                   1197:   PCRE_ERROR_BADOPTION      the value of \fIwhat\fP was invalid
1.1.1.4 ! misho    1198:   PCRE_ERROR_UNSET          the requested field is not set
1.1       misho    1199: .sp
                   1200: The "magic number" is placed at the start of each compiled pattern as an simple
1.1.1.2   misho    1201: check against passing an arbitrary memory pointer. The endianness error can
                   1202: occur if a compiled pattern is saved and reloaded on a different host. Here is
                   1203: a typical call of \fBpcre_fullinfo()\fP, to obtain the length of the compiled
                   1204: pattern:
1.1       misho    1205: .sp
                   1206:   int rc;
                   1207:   size_t length;
                   1208:   rc = pcre_fullinfo(
                   1209:     re,               /* result of pcre_compile() */
                   1210:     sd,               /* result of pcre_study(), or NULL */
                   1211:     PCRE_INFO_SIZE,   /* what is required */
                   1212:     &length);         /* where to put the data */
                   1213: .sp
                   1214: The possible values for the third argument are defined in \fBpcre.h\fP, and are
                   1215: as follows:
                   1216: .sp
                   1217:   PCRE_INFO_BACKREFMAX
                   1218: .sp
                   1219: Return the number of the highest back reference in the pattern. The fourth
                   1220: argument should point to an \fBint\fP variable. Zero is returned if there are
                   1221: no back references.
                   1222: .sp
                   1223:   PCRE_INFO_CAPTURECOUNT
                   1224: .sp
                   1225: Return the number of capturing subpatterns in the pattern. The fourth argument
                   1226: should point to an \fBint\fP variable.
                   1227: .sp
                   1228:   PCRE_INFO_DEFAULT_TABLES
                   1229: .sp
                   1230: Return a pointer to the internal default character tables within PCRE. The
                   1231: fourth argument should point to an \fBunsigned char *\fP variable. This
                   1232: information call is provided for internal use by the \fBpcre_study()\fP
                   1233: function. External callers can cause PCRE to use its internal tables by passing
                   1234: a NULL table pointer.
                   1235: .sp
                   1236:   PCRE_INFO_FIRSTBYTE
                   1237: .sp
1.1.1.2   misho    1238: Return information about the first data unit of any matched string, for a
                   1239: non-anchored pattern. (The name of this option refers to the 8-bit library,
                   1240: where data units are bytes.) The fourth argument should point to an \fBint\fP
                   1241: variable.
                   1242: .P
                   1243: If there is a fixed first value, for example, the letter "c" from a pattern
                   1244: such as (cat|cow|coyote), its value is returned. In the 8-bit library, the
1.1.1.4 ! misho    1245: value is always less than 256. In the 16-bit library the value can be up to
        !          1246: 0xffff. In the 32-bit library the value can be up to 0x10ffff.
1.1       misho    1247: .P
1.1.1.2   misho    1248: If there is no fixed first value, and if either
1.1       misho    1249: .sp
                   1250: (a) the pattern was compiled with the PCRE_MULTILINE option, and every branch
                   1251: starts with "^", or
                   1252: .sp
                   1253: (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set
                   1254: (if it were set, the pattern would be anchored),
                   1255: .sp
                   1256: -1 is returned, indicating that the pattern matches only at the start of a
                   1257: subject string or after any newline within the string. Otherwise -2 is
                   1258: returned. For anchored patterns, -2 is returned.
1.1.1.4 ! misho    1259: .P
        !          1260: Since for the 32-bit library using the non-UTF-32 mode, this function is unable
        !          1261: to return the full 32-bit range of the character, this value is deprecated;
        !          1262: instead the PCRE_INFO_FIRSTCHARACTERFLAGS and PCRE_INFO_FIRSTCHARACTER values
        !          1263: should be used.
1.1       misho    1264: .sp
                   1265:   PCRE_INFO_FIRSTTABLE
                   1266: .sp
                   1267: If the pattern was studied, and this resulted in the construction of a 256-bit
1.1.1.2   misho    1268: table indicating a fixed set of values for the first data unit in any matching
1.1       misho    1269: string, a pointer to the table is returned. Otherwise NULL is returned. The
                   1270: fourth argument should point to an \fBunsigned char *\fP variable.
                   1271: .sp
                   1272:   PCRE_INFO_HASCRORLF
                   1273: .sp
                   1274: Return 1 if the pattern contains any explicit matches for CR or LF characters,
                   1275: otherwise 0. The fourth argument should point to an \fBint\fP variable. An
                   1276: explicit match is either a literal CR or LF character, or \er or \en.
                   1277: .sp
                   1278:   PCRE_INFO_JCHANGED
                   1279: .sp
                   1280: Return 1 if the (?J) or (?-J) option setting is used in the pattern, otherwise
                   1281: 0. The fourth argument should point to an \fBint\fP variable. (?J) and
                   1282: (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
                   1283: .sp
                   1284:   PCRE_INFO_JIT
                   1285: .sp
1.1.1.3   misho    1286: Return 1 if the pattern was studied with one of the JIT options, and
1.1       misho    1287: just-in-time compiling was successful. The fourth argument should point to an
                   1288: \fBint\fP variable. A return value of 0 means that JIT support is not available
1.1.1.3   misho    1289: in this version of PCRE, or that the pattern was not studied with a JIT option,
                   1290: or that the JIT compiler could not handle this particular pattern. See the
1.1       misho    1291: .\" HREF
                   1292: \fBpcrejit\fP
                   1293: .\"
                   1294: documentation for details of what can and cannot be handled.
                   1295: .sp
                   1296:   PCRE_INFO_JITSIZE
                   1297: .sp
1.1.1.3   misho    1298: If the pattern was successfully studied with a JIT option, return the size of
                   1299: the JIT compiled code, otherwise return zero. The fourth argument should point
                   1300: to a \fBsize_t\fP variable.
1.1       misho    1301: .sp
                   1302:   PCRE_INFO_LASTLITERAL
                   1303: .sp
1.1.1.2   misho    1304: Return the value of the rightmost literal data unit that must exist in any
                   1305: matched string, other than at its start, if such a value has been recorded. The
                   1306: fourth argument should point to an \fBint\fP variable. If there is no such
                   1307: value, -1 is returned. For anchored patterns, a last literal value is recorded
                   1308: only if it follows something of variable length. For example, for the pattern
1.1       misho    1309: /^a\ed+z\ed+/ the returned value is "z", but for /^a\edz\ed/ the returned value
                   1310: is -1.
1.1.1.4 ! misho    1311: .P
        !          1312: Since for the 32-bit library using the non-UTF-32 mode, this function is unable
        !          1313: to return the full 32-bit range of the character, this value is deprecated;
        !          1314: instead the PCRE_INFO_REQUIREDCHARFLAGS and PCRE_INFO_REQUIREDCHAR values should
        !          1315: be used.
        !          1316: .sp
        !          1317:   PCRE_INFO_MATCHLIMIT
        !          1318: .sp
        !          1319: If the pattern set a match limit by including an item of the form
        !          1320: (*LIMIT_MATCH=nnnn) at the start, the value is returned. The fourth argument
        !          1321: should point to an unsigned 32-bit integer. If no such value has been set, the
        !          1322: call to \fBpcre_fullinfo()\fP returns the error PCRE_ERROR_UNSET.
1.1       misho    1323: .sp
1.1.1.3   misho    1324:   PCRE_INFO_MAXLOOKBEHIND
                   1325: .sp
1.1.1.4 ! misho    1326: Return the number of characters (NB not data units) in the longest lookbehind
        !          1327: assertion in the pattern. This information is useful when doing multi-segment
        !          1328: matching using the partial matching facilities. Note that the simple assertions
        !          1329: \eb and \eB require a one-character lookbehind. \eA also registers a
        !          1330: one-character lookbehind, though it does not actually inspect the previous
        !          1331: character. This is to ensure that at least one character from the old segment
        !          1332: is retained when a new segment is processed. Otherwise, if there are no
        !          1333: lookbehinds in the pattern, \eA might match incorrectly at the start of a new
        !          1334: segment.
1.1.1.3   misho    1335: .sp
1.1       misho    1336:   PCRE_INFO_MINLENGTH
                   1337: .sp
                   1338: If the pattern was studied and a minimum length for matching subject strings
                   1339: was computed, its value is returned. Otherwise the returned value is -1. The
1.1.1.4 ! misho    1340: value is a number of characters, which in UTF mode may be different from the
        !          1341: number of data units. The fourth argument should point to an \fBint\fP
        !          1342: variable. A non-negative value is a lower bound to the length of any matching
        !          1343: string. There may not be any strings of that length that do actually match, but
        !          1344: every string that does match is at least that long.
1.1       misho    1345: .sp
                   1346:   PCRE_INFO_NAMECOUNT
                   1347:   PCRE_INFO_NAMEENTRYSIZE
                   1348:   PCRE_INFO_NAMETABLE
                   1349: .sp
                   1350: PCRE supports the use of named as well as numbered capturing parentheses. The
                   1351: names are just an additional way of identifying the parentheses, which still
                   1352: acquire numbers. Several convenience functions such as
                   1353: \fBpcre_get_named_substring()\fP are provided for extracting captured
                   1354: substrings by name. It is also possible to extract the data directly, by first
                   1355: converting the name to a number in order to access the correct pointers in the
                   1356: output vector (described with \fBpcre_exec()\fP below). To do the conversion,
                   1357: you need to use the name-to-number map, which is described by these three
                   1358: values.
                   1359: .P
                   1360: The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT gives
                   1361: the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size of each
                   1362: entry; both of these return an \fBint\fP value. The entry size depends on the
                   1363: length of the longest name. PCRE_INFO_NAMETABLE returns a pointer to the first
1.1.1.2   misho    1364: entry of the table. This is a pointer to \fBchar\fP in the 8-bit library, where
                   1365: the first two bytes of each entry are the number of the capturing parenthesis,
                   1366: most significant byte first. In the 16-bit library, the pointer points to
1.1.1.4 ! misho    1367: 16-bit data units, the first of which contains the parenthesis number. In the
        !          1368: 32-bit library, the pointer points to 32-bit data units, the first of which
        !          1369: contains the parenthesis number. The rest of the entry is the corresponding
        !          1370: name, zero terminated.
1.1       misho    1371: .P
                   1372: The names are in alphabetical order. Duplicate names may appear if (?| is used
                   1373: to create multiple groups with the same number, as described in the
                   1374: .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
                   1375: .\" </a>
                   1376: section on duplicate subpattern numbers
                   1377: .\"
                   1378: in the
                   1379: .\" HREF
                   1380: \fBpcrepattern\fP
                   1381: .\"
                   1382: page. Duplicate names for subpatterns with different numbers are permitted only
                   1383: if PCRE_DUPNAMES is set. In all cases of duplicate names, they appear in the
                   1384: table in the order in which they were found in the pattern. In the absence of
                   1385: (?| this is the order of increasing number; when (?| is used this is not
                   1386: necessarily the case because later subpatterns may have lower numbers.
                   1387: .P
                   1388: As a simple example of the name/number table, consider the following pattern
1.1.1.2   misho    1389: after compilation by the 8-bit library (assume PCRE_EXTENDED is set, so white
                   1390: space - including newlines - is ignored):
1.1       misho    1391: .sp
                   1392: .\" JOIN
                   1393:   (?<date> (?<year>(\ed\ed)?\ed\ed) -
                   1394:   (?<month>\ed\ed) - (?<day>\ed\ed) )
                   1395: .sp
                   1396: There are four named subpatterns, so the table has four entries, and each entry
                   1397: in the table is eight bytes long. The table is as follows, with non-printing
                   1398: bytes shows in hexadecimal, and undefined bytes shown as ??:
                   1399: .sp
                   1400:   00 01 d  a  t  e  00 ??
                   1401:   00 05 d  a  y  00 ?? ??
                   1402:   00 04 m  o  n  t  h  00
                   1403:   00 02 y  e  a  r  00 ??
                   1404: .sp
                   1405: When writing code to extract data from named subpatterns using the
                   1406: name-to-number map, remember that the length of the entries is likely to be
                   1407: different for each compiled pattern.
                   1408: .sp
                   1409:   PCRE_INFO_OKPARTIAL
                   1410: .sp
                   1411: Return 1 if the pattern can be used for partial matching with
                   1412: \fBpcre_exec()\fP, otherwise 0. The fourth argument should point to an
                   1413: \fBint\fP variable. From release 8.00, this always returns 1, because the
                   1414: restrictions that previously applied to partial matching have been lifted. The
                   1415: .\" HREF
                   1416: \fBpcrepartial\fP
                   1417: .\"
                   1418: documentation gives details of partial matching.
                   1419: .sp
                   1420:   PCRE_INFO_OPTIONS
                   1421: .sp
                   1422: Return a copy of the options with which the pattern was compiled. The fourth
                   1423: argument should point to an \fBunsigned long int\fP variable. These option bits
                   1424: are those specified in the call to \fBpcre_compile()\fP, modified by any
                   1425: top-level option settings at the start of the pattern itself. In other words,
                   1426: they are the options that will be in force when matching starts. For example,
                   1427: if the pattern /(?im)abc(?-i)d/ is compiled with the PCRE_EXTENDED option, the
                   1428: result is PCRE_CASELESS, PCRE_MULTILINE, and PCRE_EXTENDED.
                   1429: .P
                   1430: A pattern is automatically anchored by PCRE if all of its top-level
                   1431: alternatives begin with one of the following:
                   1432: .sp
                   1433:   ^     unless PCRE_MULTILINE is set
                   1434:   \eA    always
                   1435:   \eG    always
                   1436: .\" JOIN
                   1437:   .*    if PCRE_DOTALL is set and there are no back
                   1438:           references to the subpattern in which .* appears
                   1439: .sp
                   1440: For such patterns, the PCRE_ANCHORED bit is set in the options returned by
                   1441: \fBpcre_fullinfo()\fP.
                   1442: .sp
1.1.1.4 ! misho    1443:   PCRE_INFO_RECURSIONLIMIT
        !          1444: .sp
        !          1445: If the pattern set a recursion limit by including an item of the form
        !          1446: (*LIMIT_RECURSION=nnnn) at the start, the value is returned. The fourth
        !          1447: argument should point to an unsigned 32-bit integer. If no such value has been
        !          1448: set, the call to \fBpcre_fullinfo()\fP returns the error PCRE_ERROR_UNSET.
        !          1449: .sp
1.1       misho    1450:   PCRE_INFO_SIZE
                   1451: .sp
1.1.1.4 ! misho    1452: Return the size of the compiled pattern in bytes (for all three libraries). The
1.1.1.2   misho    1453: fourth argument should point to a \fBsize_t\fP variable. This value does not
                   1454: include the size of the \fBpcre\fP structure that is returned by
                   1455: \fBpcre_compile()\fP. The value that is passed as the argument to
                   1456: \fBpcre_malloc()\fP when \fBpcre_compile()\fP is getting memory in which to
                   1457: place the compiled data is the value returned by this option plus the size of
                   1458: the \fBpcre\fP structure. Studying a compiled pattern, with or without JIT,
                   1459: does not alter the value returned by this option.
1.1       misho    1460: .sp
                   1461:   PCRE_INFO_STUDYSIZE
                   1462: .sp
1.1.1.4 ! misho    1463: Return the size in bytes (for all three libraries) of the data block pointed to
        !          1464: by the \fIstudy_data\fP field in a \fBpcre_extra\fP block. If \fBpcre_extra\fP
        !          1465: is NULL, or there is no study data, zero is returned. The fourth argument
        !          1466: should point to a \fBsize_t\fP variable. The \fIstudy_data\fP field is set by
        !          1467: \fBpcre_study()\fP to record information that will speed up matching (see the
        !          1468: section entitled
1.1       misho    1469: .\" HTML <a href="#studyingapattern">
                   1470: .\" </a>
                   1471: "Studying a pattern"
                   1472: .\"
                   1473: above). The format of the \fIstudy_data\fP block is private, but its length
                   1474: is made available via this option so that it can be saved and restored (see the
                   1475: .\" HREF
                   1476: \fBpcreprecompile\fP
                   1477: .\"
                   1478: documentation for details).
1.1.1.4 ! misho    1479: .sp
        !          1480:   PCRE_INFO_FIRSTCHARACTERFLAGS
        !          1481: .sp
        !          1482: Return information about the first data unit of any matched string, for a
        !          1483: non-anchored pattern. The fourth argument should point to an \fBint\fP
        !          1484: variable.
        !          1485: .P
        !          1486: If there is a fixed first value, for example, the letter "c" from a pattern
        !          1487: such as (cat|cow|coyote), 1 is returned, and the character value can be
        !          1488: retrieved using PCRE_INFO_FIRSTCHARACTER.
        !          1489: .P
        !          1490: If there is no fixed first value, and if either
        !          1491: .sp
        !          1492: (a) the pattern was compiled with the PCRE_MULTILINE option, and every branch
        !          1493: starts with "^", or
        !          1494: .sp
        !          1495: (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set
        !          1496: (if it were set, the pattern would be anchored),
        !          1497: .sp
        !          1498: 2 is returned, indicating that the pattern matches only at the start of a
        !          1499: subject string or after any newline within the string. Otherwise 0 is
        !          1500: returned. For anchored patterns, 0 is returned.
        !          1501: .sp
        !          1502:   PCRE_INFO_FIRSTCHARACTER
        !          1503: .sp
        !          1504: Return the fixed first character value, if PCRE_INFO_FIRSTCHARACTERFLAGS
        !          1505: returned 1; otherwise returns 0. The fourth argument should point to an
        !          1506: \fBuint_t\fP variable.
        !          1507: .P
        !          1508: In the 8-bit library, the value is always less than 256. In the 16-bit library
        !          1509: the value can be up to 0xffff. In the 32-bit library in UTF-32 mode the value
        !          1510: can be up to 0x10ffff, and up to 0xffffffff when not using UTF-32 mode.
        !          1511: .P
        !          1512: If there is no fixed first value, and if either
        !          1513: .sp
        !          1514: (a) the pattern was compiled with the PCRE_MULTILINE option, and every branch
        !          1515: starts with "^", or
        !          1516: .sp
        !          1517: (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set
        !          1518: (if it were set, the pattern would be anchored),
        !          1519: .sp
        !          1520: -1 is returned, indicating that the pattern matches only at the start of a
        !          1521: subject string or after any newline within the string. Otherwise -2 is
        !          1522: returned. For anchored patterns, -2 is returned.
        !          1523: .sp
        !          1524:   PCRE_INFO_REQUIREDCHARFLAGS
        !          1525: .sp
        !          1526: Returns 1 if there is a rightmost literal data unit that must exist in any
        !          1527: matched string, other than at its start. The fourth argument should  point to
        !          1528: an \fBint\fP variable. If there is no such value, 0 is returned. If returning
        !          1529: 1, the character value itself can be retrieved using PCRE_INFO_REQUIREDCHAR.
        !          1530: .P
        !          1531: For anchored patterns, a last literal value is recorded only if it follows
        !          1532: something of variable length. For example, for the pattern /^a\ed+z\ed+/ the
        !          1533: returned value 1 (with "z" returned from PCRE_INFO_REQUIREDCHAR), but for
        !          1534: /^a\edz\ed/ the returned value is 0.
        !          1535: .sp
        !          1536:   PCRE_INFO_REQUIREDCHAR
        !          1537: .sp
        !          1538: Return the value of the rightmost literal data unit that must exist in any
        !          1539: matched string, other than at its start, if such a value has been recorded. The
        !          1540: fourth argument should point to an \fBuint32_t\fP variable. If there is no such
        !          1541: value, 0 is returned.
1.1       misho    1542: .
                   1543: .
                   1544: .SH "REFERENCE COUNTS"
                   1545: .rs
                   1546: .sp
                   1547: .B int pcre_refcount(pcre *\fIcode\fP, int \fIadjust\fP);
                   1548: .PP
                   1549: The \fBpcre_refcount()\fP function is used to maintain a reference count in the
                   1550: data block that contains a compiled pattern. It is provided for the benefit of
                   1551: applications that operate in an object-oriented manner, where different parts
                   1552: of the application may be using the same compiled pattern, but you want to free
                   1553: the block when they are all done.
                   1554: .P
                   1555: When a pattern is compiled, the reference count field is initialized to zero.
                   1556: It is changed only by calling this function, whose action is to add the
                   1557: \fIadjust\fP value (which may be positive or negative) to it. The yield of the
                   1558: function is the new value. However, the value of the count is constrained to
                   1559: lie between 0 and 65535, inclusive. If the new value is outside these limits,
                   1560: it is forced to the appropriate limit value.
                   1561: .P
                   1562: Except when it is zero, the reference count is not correctly preserved if a
                   1563: pattern is compiled on one host and then transferred to a host whose byte-order
                   1564: is different. (This seems a highly unlikely scenario.)
                   1565: .
                   1566: .
                   1567: .SH "MATCHING A PATTERN: THE TRADITIONAL FUNCTION"
                   1568: .rs
                   1569: .sp
                   1570: .B int pcre_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
                   1571: .ti +5n
                   1572: .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
                   1573: .ti +5n
                   1574: .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP);
                   1575: .P
                   1576: The function \fBpcre_exec()\fP is called to match a subject string against a
                   1577: compiled pattern, which is passed in the \fIcode\fP argument. If the
                   1578: pattern was studied, the result of the study should be passed in the
                   1579: \fIextra\fP argument. You can call \fBpcre_exec()\fP with the same \fIcode\fP
                   1580: and \fIextra\fP arguments as many times as you like, in order to match
                   1581: different subject strings with the same pattern.
                   1582: .P
                   1583: This function is the main matching facility of the library, and it operates in
                   1584: a Perl-like manner. For specialist use there is also an alternative matching
                   1585: function, which is described
                   1586: .\" HTML <a href="#dfamatch">
                   1587: .\" </a>
                   1588: below
                   1589: .\"
                   1590: in the section about the \fBpcre_dfa_exec()\fP function.
                   1591: .P
                   1592: In most applications, the pattern will have been compiled (and optionally
                   1593: studied) in the same process that calls \fBpcre_exec()\fP. However, it is
                   1594: possible to save compiled patterns and study data, and then use them later
                   1595: in different processes, possibly even on different hosts. For a discussion
                   1596: about this, see the
                   1597: .\" HREF
                   1598: \fBpcreprecompile\fP
                   1599: .\"
                   1600: documentation.
                   1601: .P
                   1602: Here is an example of a simple call to \fBpcre_exec()\fP:
                   1603: .sp
                   1604:   int rc;
                   1605:   int ovector[30];
                   1606:   rc = pcre_exec(
                   1607:     re,             /* result of pcre_compile() */
                   1608:     NULL,           /* we didn't study the pattern */
                   1609:     "some string",  /* the subject string */
                   1610:     11,             /* the length of the subject string */
                   1611:     0,              /* start at offset 0 in the subject */
                   1612:     0,              /* default options */
                   1613:     ovector,        /* vector of integers for substring information */
                   1614:     30);            /* number of elements (NOT size in bytes) */
                   1615: .
                   1616: .
                   1617: .\" HTML <a name="extradata"></a>
                   1618: .SS "Extra data for \fBpcre_exec()\fR"
                   1619: .rs
                   1620: .sp
                   1621: If the \fIextra\fP argument is not NULL, it must point to a \fBpcre_extra\fP
                   1622: data block. The \fBpcre_study()\fP function returns such a block (when it
                   1623: doesn't return NULL), but you can also create one for yourself, and pass
                   1624: additional information in it. The \fBpcre_extra\fP block contains the following
                   1625: fields (not necessarily in this order):
                   1626: .sp
                   1627:   unsigned long int \fIflags\fP;
                   1628:   void *\fIstudy_data\fP;
                   1629:   void *\fIexecutable_jit\fP;
                   1630:   unsigned long int \fImatch_limit\fP;
                   1631:   unsigned long int \fImatch_limit_recursion\fP;
                   1632:   void *\fIcallout_data\fP;
                   1633:   const unsigned char *\fItables\fP;
                   1634:   unsigned char **\fImark\fP;
                   1635: .sp
1.1.1.2   misho    1636: In the 16-bit version of this structure, the \fImark\fP field has type
                   1637: "PCRE_UCHAR16 **".
1.1.1.4 ! misho    1638: .sp
        !          1639: In the 32-bit version of this structure, the \fImark\fP field has type
        !          1640: "PCRE_UCHAR32 **".
1.1.1.2   misho    1641: .P
1.1.1.3   misho    1642: The \fIflags\fP field is used to specify which of the other fields are set. The
                   1643: flag bits are:
1.1       misho    1644: .sp
1.1.1.3   misho    1645:   PCRE_EXTRA_CALLOUT_DATA
1.1       misho    1646:   PCRE_EXTRA_EXECUTABLE_JIT
1.1.1.3   misho    1647:   PCRE_EXTRA_MARK
1.1       misho    1648:   PCRE_EXTRA_MATCH_LIMIT
                   1649:   PCRE_EXTRA_MATCH_LIMIT_RECURSION
1.1.1.3   misho    1650:   PCRE_EXTRA_STUDY_DATA
1.1       misho    1651:   PCRE_EXTRA_TABLES
                   1652: .sp
                   1653: Other flag bits should be set to zero. The \fIstudy_data\fP field and sometimes
                   1654: the \fIexecutable_jit\fP field are set in the \fBpcre_extra\fP block that is
                   1655: returned by \fBpcre_study()\fP, together with the appropriate flag bits. You
1.1.1.3   misho    1656: should not set these yourself, but you may add to the block by setting other
                   1657: fields and their corresponding flag bits.
1.1       misho    1658: .P
                   1659: The \fImatch_limit\fP field provides a means of preventing PCRE from using up a
                   1660: vast amount of resources when running patterns that are not going to match,
                   1661: but which have a very large number of possibilities in their search trees. The
                   1662: classic example is a pattern that uses nested unlimited repeats.
                   1663: .P
                   1664: Internally, \fBpcre_exec()\fP uses a function called \fBmatch()\fP, which it
                   1665: calls repeatedly (sometimes recursively). The limit set by \fImatch_limit\fP is
                   1666: imposed on the number of times this function is called during a match, which
                   1667: has the effect of limiting the amount of backtracking that can take place. For
                   1668: patterns that are not anchored, the count restarts from zero for each position
                   1669: in the subject string.
                   1670: .P
                   1671: When \fBpcre_exec()\fP is called with a pattern that was successfully studied
1.1.1.3   misho    1672: with a JIT option, the way that the matching is executed is entirely different.
                   1673: However, there is still the possibility of runaway matching that goes on for a
                   1674: very long time, and so the \fImatch_limit\fP value is also used in this case
                   1675: (but in a different way) to limit how long the matching can continue.
1.1       misho    1676: .P
                   1677: The default value for the limit can be set when PCRE is built; the default
                   1678: default is 10 million, which handles all but the most extreme cases. You can
                   1679: override the default by suppling \fBpcre_exec()\fP with a \fBpcre_extra\fP
                   1680: block in which \fImatch_limit\fP is set, and PCRE_EXTRA_MATCH_LIMIT is set in
                   1681: the \fIflags\fP field. If the limit is exceeded, \fBpcre_exec()\fP returns
                   1682: PCRE_ERROR_MATCHLIMIT.
                   1683: .P
1.1.1.4 ! misho    1684: A value for the match limit may also be supplied by an item at the start of a
        !          1685: pattern of the form
        !          1686: .sp
        !          1687:   (*LIMIT_MATCH=d)
        !          1688: .sp
        !          1689: where d is a decimal number. However, such a setting is ignored unless d is
        !          1690: less than the limit set by the caller of \fBpcre_exec()\fP or, if no such limit
        !          1691: is set, less than the default.
        !          1692: .P
1.1       misho    1693: The \fImatch_limit_recursion\fP field is similar to \fImatch_limit\fP, but
                   1694: instead of limiting the total number of times that \fBmatch()\fP is called, it
                   1695: limits the depth of recursion. The recursion depth is a smaller number than the
                   1696: total number of calls, because not all calls to \fBmatch()\fP are recursive.
                   1697: This limit is of use only if it is set smaller than \fImatch_limit\fP.
                   1698: .P
                   1699: Limiting the recursion depth limits the amount of machine stack that can be
                   1700: used, or, when PCRE has been compiled to use memory on the heap instead of the
                   1701: stack, the amount of heap memory that can be used. This limit is not relevant,
1.1.1.3   misho    1702: and is ignored, when matching is done using JIT compiled code.
1.1       misho    1703: .P
                   1704: The default value for \fImatch_limit_recursion\fP can be set when PCRE is
                   1705: built; the default default is the same value as the default for
                   1706: \fImatch_limit\fP. You can override the default by suppling \fBpcre_exec()\fP
                   1707: with a \fBpcre_extra\fP block in which \fImatch_limit_recursion\fP is set, and
                   1708: PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in the \fIflags\fP field. If the limit
                   1709: is exceeded, \fBpcre_exec()\fP returns PCRE_ERROR_RECURSIONLIMIT.
                   1710: .P
1.1.1.4 ! misho    1711: A value for the recursion limit may also be supplied by an item at the start of
        !          1712: a pattern of the form
        !          1713: .sp
        !          1714:   (*LIMIT_RECURSION=d)
        !          1715: .sp
        !          1716: where d is a decimal number. However, such a setting is ignored unless d is
        !          1717: less than the limit set by the caller of \fBpcre_exec()\fP or, if no such limit
        !          1718: is set, less than the default.
        !          1719: .P
1.1       misho    1720: The \fIcallout_data\fP field is used in conjunction with the "callout" feature,
                   1721: and is described in the
                   1722: .\" HREF
                   1723: \fBpcrecallout\fP
                   1724: .\"
                   1725: documentation.
                   1726: .P
                   1727: The \fItables\fP field is used to pass a character tables pointer to
                   1728: \fBpcre_exec()\fP; this overrides the value that is stored with the compiled
                   1729: pattern. A non-NULL value is stored with the compiled pattern only if custom
                   1730: tables were supplied to \fBpcre_compile()\fP via its \fItableptr\fP argument.
                   1731: If NULL is passed to \fBpcre_exec()\fP using this mechanism, it forces PCRE's
                   1732: internal tables to be used. This facility is helpful when re-using patterns
                   1733: that have been saved after compiling with an external set of tables, because
                   1734: the external tables might be at a different address when \fBpcre_exec()\fP is
                   1735: called. See the
                   1736: .\" HREF
                   1737: \fBpcreprecompile\fP
                   1738: .\"
                   1739: documentation for a discussion of saving compiled patterns for later use.
                   1740: .P
                   1741: If PCRE_EXTRA_MARK is set in the \fIflags\fP field, the \fImark\fP field must
1.1.1.2   misho    1742: be set to point to a suitable variable. If the pattern contains any
1.1       misho    1743: backtracking control verbs such as (*MARK:NAME), and the execution ends up with
                   1744: a name to pass back, a pointer to the name string (zero terminated) is placed
                   1745: in the variable pointed to by the \fImark\fP field. The names are within the
                   1746: compiled pattern; if you wish to retain such a name you must copy it before
                   1747: freeing the memory of a compiled pattern. If there is no name to pass back, the
1.1.1.2   misho    1748: variable pointed to by the \fImark\fP field is set to NULL. For details of the
1.1       misho    1749: backtracking control verbs, see the section entitled
                   1750: .\" HTML <a href="pcrepattern#backtrackcontrol">
                   1751: .\" </a>
                   1752: "Backtracking control"
                   1753: .\"
                   1754: in the
                   1755: .\" HREF
                   1756: \fBpcrepattern\fP
                   1757: .\"
                   1758: documentation.
                   1759: .
                   1760: .
                   1761: .\" HTML <a name="execoptions"></a>
                   1762: .SS "Option bits for \fBpcre_exec()\fP"
                   1763: .rs
                   1764: .sp
                   1765: The unused bits of the \fIoptions\fP argument for \fBpcre_exec()\fP must be
                   1766: zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_\fIxxx\fP,
                   1767: PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
1.1.1.3   misho    1768: PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_HARD, and
                   1769: PCRE_PARTIAL_SOFT.
1.1       misho    1770: .P
1.1.1.3   misho    1771: If the pattern was successfully studied with one of the just-in-time (JIT)
                   1772: compile options, the only supported options for JIT execution are
                   1773: PCRE_NO_UTF8_CHECK, PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY,
                   1774: PCRE_NOTEMPTY_ATSTART, PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT. If an
                   1775: unsupported option is used, JIT execution is disabled and the normal
                   1776: interpretive code in \fBpcre_exec()\fP is run.
1.1       misho    1777: .sp
                   1778:   PCRE_ANCHORED
                   1779: .sp
                   1780: The PCRE_ANCHORED option limits \fBpcre_exec()\fP to matching at the first
                   1781: matching position. If a pattern was compiled with PCRE_ANCHORED, or turned out
                   1782: to be anchored by virtue of its contents, it cannot be made unachored at
                   1783: matching time.
                   1784: .sp
                   1785:   PCRE_BSR_ANYCRLF
                   1786:   PCRE_BSR_UNICODE
                   1787: .sp
                   1788: These options (which are mutually exclusive) control what the \eR escape
                   1789: sequence matches. The choice is either to match only CR, LF, or CRLF, or to
                   1790: match any Unicode newline sequence. These options override the choice that was
                   1791: made or defaulted when the pattern was compiled.
                   1792: .sp
                   1793:   PCRE_NEWLINE_CR
                   1794:   PCRE_NEWLINE_LF
                   1795:   PCRE_NEWLINE_CRLF
                   1796:   PCRE_NEWLINE_ANYCRLF
                   1797:   PCRE_NEWLINE_ANY
                   1798: .sp
                   1799: These options override the newline definition that was chosen or defaulted when
                   1800: the pattern was compiled. For details, see the description of
                   1801: \fBpcre_compile()\fP above. During matching, the newline choice affects the
                   1802: behaviour of the dot, circumflex, and dollar metacharacters. It may also alter
                   1803: the way the match position is advanced after a match failure for an unanchored
                   1804: pattern.
                   1805: .P
                   1806: When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is set, and a
                   1807: match attempt for an unanchored pattern fails when the current position is at a
                   1808: CRLF sequence, and the pattern contains no explicit matches for CR or LF
                   1809: characters, the match position is advanced by two characters instead of one, in
                   1810: other words, to after the CRLF.
                   1811: .P
                   1812: The above rule is a compromise that makes the most common cases work as
                   1813: expected. For example, if the pattern is .+A (and the PCRE_DOTALL option is not
                   1814: set), it does not match the string "\er\enA" because, after failing at the
                   1815: start, it skips both the CR and the LF before retrying. However, the pattern
                   1816: [\er\en]A does match that string, because it contains an explicit CR or LF
                   1817: reference, and so advances only by one character after the first failure.
                   1818: .P
                   1819: An explicit match for CR of LF is either a literal appearance of one of those
                   1820: characters, or one of the \er or \en escape sequences. Implicit matches such as
                   1821: [^X] do not count, nor does \es (which includes CR and LF in the characters
                   1822: that it matches).
                   1823: .P
                   1824: Notwithstanding the above, anomalous effects may still occur when CRLF is a
                   1825: valid newline sequence and explicit \er or \en escapes appear in the pattern.
                   1826: .sp
                   1827:   PCRE_NOTBOL
                   1828: .sp
                   1829: This option specifies that first character of the subject string is not the
                   1830: beginning of a line, so the circumflex metacharacter should not match before
                   1831: it. Setting this without PCRE_MULTILINE (at compile time) causes circumflex
                   1832: never to match. This option affects only the behaviour of the circumflex
                   1833: metacharacter. It does not affect \eA.
                   1834: .sp
                   1835:   PCRE_NOTEOL
                   1836: .sp
                   1837: This option specifies that the end of the subject string is not the end of a
                   1838: line, so the dollar metacharacter should not match it nor (except in multiline
                   1839: mode) a newline immediately before it. Setting this without PCRE_MULTILINE (at
                   1840: compile time) causes dollar never to match. This option affects only the
                   1841: behaviour of the dollar metacharacter. It does not affect \eZ or \ez.
                   1842: .sp
                   1843:   PCRE_NOTEMPTY
                   1844: .sp
                   1845: An empty string is not considered to be a valid match if this option is set. If
                   1846: there are alternatives in the pattern, they are tried. If all the alternatives
                   1847: match the empty string, the entire match fails. For example, if the pattern
                   1848: .sp
                   1849:   a?b?
                   1850: .sp
                   1851: is applied to a string not beginning with "a" or "b", it matches an empty
                   1852: string at the start of the subject. With PCRE_NOTEMPTY set, this match is not
                   1853: valid, so PCRE searches further into the string for occurrences of "a" or "b".
                   1854: .sp
                   1855:   PCRE_NOTEMPTY_ATSTART
                   1856: .sp
                   1857: This is like PCRE_NOTEMPTY, except that an empty string match that is not at
                   1858: the start of the subject is permitted. If the pattern is anchored, such a match
                   1859: can occur only if the pattern contains \eK.
                   1860: .P
                   1861: Perl has no direct equivalent of PCRE_NOTEMPTY or PCRE_NOTEMPTY_ATSTART, but it
                   1862: does make a special case of a pattern match of the empty string within its
                   1863: \fBsplit()\fP function, and when using the /g modifier. It is possible to
                   1864: emulate Perl's behaviour after matching a null string by first trying the match
                   1865: again at the same offset with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then
                   1866: if that fails, by advancing the starting offset (see below) and trying an
                   1867: ordinary match again. There is some code that demonstrates how to do this in
                   1868: the
                   1869: .\" HREF
                   1870: \fBpcredemo\fP
                   1871: .\"
                   1872: sample program. In the most general case, you have to check to see if the
                   1873: newline convention recognizes CRLF as a newline, and if so, and the current
                   1874: character is CR followed by LF, advance the starting offset by two characters
                   1875: instead of one.
                   1876: .sp
                   1877:   PCRE_NO_START_OPTIMIZE
                   1878: .sp
                   1879: There are a number of optimizations that \fBpcre_exec()\fP uses at the start of
                   1880: a match, in order to speed up the process. For example, if it is known that an
                   1881: unanchored match must start with a specific character, it searches the subject
                   1882: for that character, and fails immediately if it cannot find it, without
                   1883: actually running the main matching function. This means that a special item
                   1884: such as (*COMMIT) at the start of a pattern is not considered until after a
1.1.1.4 ! misho    1885: suitable starting point for the match has been found. Also, when callouts or
        !          1886: (*MARK) items are in use, these "start-up" optimizations can cause them to be
        !          1887: skipped if the pattern is never actually used. The start-up optimizations are
        !          1888: in effect a pre-scan of the subject that takes place before the pattern is run.
1.1       misho    1889: .P
                   1890: The PCRE_NO_START_OPTIMIZE option disables the start-up optimizations, possibly
                   1891: causing performance to suffer, but ensuring that in cases where the result is
                   1892: "no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK)
                   1893: are considered at every possible starting position in the subject string. If
                   1894: PCRE_NO_START_OPTIMIZE is set at compile time, it cannot be unset at matching
1.1.1.4 ! misho    1895: time. The use of PCRE_NO_START_OPTIMIZE at matching time (that is, passing it
        !          1896: to \fBpcre_exec()\fP) disables JIT execution; in this situation, matching is
        !          1897: always done using interpretively.
1.1       misho    1898: .P
                   1899: Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation.
                   1900: Consider the pattern
                   1901: .sp
                   1902:   (*COMMIT)ABC
                   1903: .sp
                   1904: When this is compiled, PCRE records the fact that a match must start with the
                   1905: character "A". Suppose the subject string is "DEFABC". The start-up
                   1906: optimization scans along the subject, finds "A" and runs the first match
                   1907: attempt from there. The (*COMMIT) item means that the pattern must match the
                   1908: current starting position, which in this case, it does. However, if the same
                   1909: match is run with PCRE_NO_START_OPTIMIZE set, the initial scan along the
                   1910: subject string does not happen. The first match attempt is run starting from
                   1911: "D" and when this fails, (*COMMIT) prevents any further matches being tried, so
                   1912: the overall result is "no match". If the pattern is studied, more start-up
                   1913: optimizations may be used. For example, a minimum length for the subject may be
                   1914: recorded. Consider the pattern
                   1915: .sp
                   1916:   (*MARK:A)(X|Y)
                   1917: .sp
                   1918: The minimum length for a match is one character. If the subject is "ABC", there
                   1919: will be attempts to match "ABC", "BC", "C", and then finally an empty string.
                   1920: If the pattern is studied, the final attempt does not take place, because PCRE
                   1921: knows that the subject is too short, and so the (*MARK) is never encountered.
                   1922: In this case, studying the pattern does not affect the overall match result,
                   1923: which is still "no match", but it does affect the auxiliary information that is
                   1924: returned.
                   1925: .sp
                   1926:   PCRE_NO_UTF8_CHECK
                   1927: .sp
                   1928: When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8
                   1929: string is automatically checked when \fBpcre_exec()\fP is subsequently called.
1.1.1.3   misho    1930: The entire string is checked before any other processing takes place. The value
                   1931: of \fIstartoffset\fP is also checked to ensure that it points to the start of a
                   1932: UTF-8 character. There is a discussion about the
                   1933: .\" HTML <a href="pcreunicode.html#utf8strings">
                   1934: .\" </a>
                   1935: validity of UTF-8 strings
                   1936: .\"
                   1937: in the
1.1       misho    1938: .\" HREF
1.1.1.2   misho    1939: \fBpcreunicode\fP
1.1       misho    1940: .\"
1.1.1.2   misho    1941: page. If an invalid sequence of bytes is found, \fBpcre_exec()\fP returns the
                   1942: error PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is a
                   1943: truncated character at the end of the subject, PCRE_ERROR_SHORTUTF8. In both
                   1944: cases, information about the precise nature of the error may also be returned
                   1945: (see the descriptions of these errors in the section entitled \fIError return
                   1946: values from\fP \fBpcre_exec()\fP
1.1       misho    1947: .\" HTML <a href="#errorlist">
                   1948: .\" </a>
                   1949: below).
                   1950: .\"
                   1951: If \fIstartoffset\fP contains a value that does not point to the start of a
                   1952: UTF-8 character (or to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is
                   1953: returned.
                   1954: .P
                   1955: If you already know that your subject is valid, and you want to skip these
                   1956: checks for performance reasons, you can set the PCRE_NO_UTF8_CHECK option when
                   1957: calling \fBpcre_exec()\fP. You might want to do this for the second and
                   1958: subsequent calls to \fBpcre_exec()\fP if you are making repeated calls to find
                   1959: all the matches in a single subject string. However, you should be sure that
1.1.1.2   misho    1960: the value of \fIstartoffset\fP points to the start of a character (or the end
                   1961: of the subject). When PCRE_NO_UTF8_CHECK is set, the effect of passing an
                   1962: invalid string as a subject or an invalid value of \fIstartoffset\fP is
1.1       misho    1963: undefined. Your program may crash.
                   1964: .sp
                   1965:   PCRE_PARTIAL_HARD
                   1966:   PCRE_PARTIAL_SOFT
                   1967: .sp
                   1968: These options turn on the partial matching feature. For backwards
                   1969: compatibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial match
                   1970: occurs if the end of the subject string is reached successfully, but there are
                   1971: not enough subject characters to complete the match. If this happens when
                   1972: PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set, matching continues by
                   1973: testing any remaining alternatives. Only if no complete match can be found is
                   1974: PCRE_ERROR_PARTIAL returned instead of PCRE_ERROR_NOMATCH. In other words,
                   1975: PCRE_PARTIAL_SOFT says that the caller is prepared to handle a partial match,
                   1976: but only if no complete match can be found.
                   1977: .P
                   1978: If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this case, if a
                   1979: partial match is found, \fBpcre_exec()\fP immediately returns
                   1980: PCRE_ERROR_PARTIAL, without considering any other alternatives. In other words,
                   1981: when PCRE_PARTIAL_HARD is set, a partial match is considered to be more
                   1982: important that an alternative complete match.
                   1983: .P
                   1984: In both cases, the portion of the string that was inspected when the partial
                   1985: match was found is set as the first matching string. There is a more detailed
                   1986: discussion of partial and multi-segment matching, with examples, in the
                   1987: .\" HREF
                   1988: \fBpcrepartial\fP
                   1989: .\"
                   1990: documentation.
                   1991: .
                   1992: .
                   1993: .SS "The string to be matched by \fBpcre_exec()\fP"
                   1994: .rs
                   1995: .sp
                   1996: The subject string is passed to \fBpcre_exec()\fP as a pointer in
1.1.1.4 ! misho    1997: \fIsubject\fP, a length in \fIlength\fP, and a starting offset in
        !          1998: \fIstartoffset\fP. The units for \fIlength\fP and \fIstartoffset\fP are bytes
        !          1999: for the 8-bit library, 16-bit data items for the 16-bit library, and 32-bit
        !          2000: data items for the 32-bit library.
        !          2001: .P
        !          2002: If \fIstartoffset\fP is negative or greater than the length of the subject,
        !          2003: \fBpcre_exec()\fP returns PCRE_ERROR_BADOFFSET. When the starting offset is
        !          2004: zero, the search for a match starts at the beginning of the subject, and this
        !          2005: is by far the most common case. In UTF-8 or UTF-16 mode, the offset must point
        !          2006: to the start of a character, or the end of the subject (in UTF-32 mode, one
        !          2007: data unit equals one character, so all offsets are valid). Unlike the pattern
        !          2008: string, the subject may contain binary zeroes.
1.1       misho    2009: .P
                   2010: A non-zero starting offset is useful when searching for another match in the
                   2011: same subject by calling \fBpcre_exec()\fP again after a previous success.
                   2012: Setting \fIstartoffset\fP differs from just passing over a shortened string and
                   2013: setting PCRE_NOTBOL in the case of a pattern that begins with any kind of
                   2014: lookbehind. For example, consider the pattern
                   2015: .sp
                   2016:   \eBiss\eB
                   2017: .sp
                   2018: which finds occurrences of "iss" in the middle of words. (\eB matches only if
                   2019: the current position in the subject is not a word boundary.) When applied to
                   2020: the string "Mississipi" the first call to \fBpcre_exec()\fP finds the first
                   2021: occurrence. If \fBpcre_exec()\fP is called again with just the remainder of the
                   2022: subject, namely "issipi", it does not match, because \eB is always false at the
                   2023: start of the subject, which is deemed to be a word boundary. However, if
                   2024: \fBpcre_exec()\fP is passed the entire string again, but with \fIstartoffset\fP
                   2025: set to 4, it finds the second occurrence of "iss" because it is able to look
                   2026: behind the starting point to discover that it is preceded by a letter.
                   2027: .P
                   2028: Finding all the matches in a subject is tricky when the pattern can match an
                   2029: empty string. It is possible to emulate Perl's /g behaviour by first trying the
                   2030: match again at the same offset, with the PCRE_NOTEMPTY_ATSTART and
                   2031: PCRE_ANCHORED options, and then if that fails, advancing the starting offset
                   2032: and trying an ordinary match again. There is some code that demonstrates how to
                   2033: do this in the
                   2034: .\" HREF
                   2035: \fBpcredemo\fP
                   2036: .\"
                   2037: sample program. In the most general case, you have to check to see if the
                   2038: newline convention recognizes CRLF as a newline, and if so, and the current
                   2039: character is CR followed by LF, advance the starting offset by two characters
                   2040: instead of one.
                   2041: .P
                   2042: If a non-zero starting offset is passed when the pattern is anchored, one
                   2043: attempt to match at the given offset is made. This can only succeed if the
                   2044: pattern does not require the match to be at the start of the subject.
                   2045: .
                   2046: .
                   2047: .SS "How \fBpcre_exec()\fP returns captured substrings"
                   2048: .rs
                   2049: .sp
                   2050: In general, a pattern matches a certain portion of the subject, and in
                   2051: addition, further substrings from the subject may be picked out by parts of the
                   2052: pattern. Following the usage in Jeffrey Friedl's book, this is called
                   2053: "capturing" in what follows, and the phrase "capturing subpattern" is used for
                   2054: a fragment of a pattern that picks out a substring. PCRE supports several other
                   2055: kinds of parenthesized subpattern that do not cause substrings to be captured.
                   2056: .P
                   2057: Captured substrings are returned to the caller via a vector of integers whose
                   2058: address is passed in \fIovector\fP. The number of elements in the vector is
                   2059: passed in \fIovecsize\fP, which must be a non-negative number. \fBNote\fP: this
                   2060: argument is NOT the size of \fIovector\fP in bytes.
                   2061: .P
                   2062: The first two-thirds of the vector is used to pass back captured substrings,
                   2063: each substring using a pair of integers. The remaining third of the vector is
                   2064: used as workspace by \fBpcre_exec()\fP while matching capturing subpatterns,
                   2065: and is not available for passing back information. The number passed in
                   2066: \fIovecsize\fP should always be a multiple of three. If it is not, it is
                   2067: rounded down.
                   2068: .P
                   2069: When a match is successful, information about captured substrings is returned
                   2070: in pairs of integers, starting at the beginning of \fIovector\fP, and
                   2071: continuing up to two-thirds of its length at the most. The first element of
1.1.1.4 ! misho    2072: each pair is set to the offset of the first character in a substring, and the
        !          2073: second is set to the offset of the first character after the end of a
        !          2074: substring. These values are always data unit offsets, even in UTF mode. They
        !          2075: are byte offsets in the 8-bit library, 16-bit data item offsets in the 16-bit
        !          2076: library, and 32-bit data item offsets in the 32-bit library. \fBNote\fP: they
        !          2077: are not character counts.
1.1       misho    2078: .P
                   2079: The first pair of integers, \fIovector[0]\fP and \fIovector[1]\fP, identify the
                   2080: portion of the subject string matched by the entire pattern. The next pair is
                   2081: used for the first capturing subpattern, and so on. The value returned by
                   2082: \fBpcre_exec()\fP is one more than the highest numbered pair that has been set.
                   2083: For example, if two substrings have been captured, the returned value is 3. If
                   2084: there are no capturing subpatterns, the return value from a successful match is
                   2085: 1, indicating that just the first pair of offsets has been set.
                   2086: .P
                   2087: If a capturing subpattern is matched repeatedly, it is the last portion of the
                   2088: string that it matched that is returned.
                   2089: .P
                   2090: If the vector is too small to hold all the captured substring offsets, it is
                   2091: used as far as possible (up to two-thirds of its length), and the function
1.1.1.3   misho    2092: returns a value of zero. If neither the actual string matched nor any captured
1.1       misho    2093: substrings are of interest, \fBpcre_exec()\fP may be called with \fIovector\fP
                   2094: passed as NULL and \fIovecsize\fP as zero. However, if the pattern contains
                   2095: back references and the \fIovector\fP is not big enough to remember the related
                   2096: substrings, PCRE has to get additional memory for use during matching. Thus it
                   2097: is usually advisable to supply an \fIovector\fP of reasonable size.
                   2098: .P
                   2099: There are some cases where zero is returned (indicating vector overflow) when
                   2100: in fact the vector is exactly the right size for the final match. For example,
                   2101: consider the pattern
                   2102: .sp
                   2103:   (a)(?:(b)c|bd)
                   2104: .sp
                   2105: If a vector of 6 elements (allowing for only 1 captured substring) is given
                   2106: with subject string "abd", \fBpcre_exec()\fP will try to set the second
                   2107: captured string, thereby recording a vector overflow, before failing to match
                   2108: "c" and backing up to try the second alternative. The zero return, however,
                   2109: does correctly indicate that the maximum number of slots (namely 2) have been
                   2110: filled. In similar cases where there is temporary overflow, but the final
                   2111: number of used slots is actually less than the maximum, a non-zero value is
                   2112: returned.
                   2113: .P
                   2114: The \fBpcre_fullinfo()\fP function can be used to find out how many capturing
                   2115: subpatterns there are in a compiled pattern. The smallest size for
                   2116: \fIovector\fP that will allow for \fIn\fP captured substrings, in addition to
                   2117: the offsets of the substring matched by the whole pattern, is (\fIn\fP+1)*3.
                   2118: .P
                   2119: It is possible for capturing subpattern number \fIn+1\fP to match some part of
                   2120: the subject when subpattern \fIn\fP has not been used at all. For example, if
                   2121: the string "abc" is matched against the pattern (a|(z))(bc) the return from the
                   2122: function is 4, and subpatterns 1 and 3 are matched, but 2 is not. When this
                   2123: happens, both values in the offset pairs corresponding to unused subpatterns
                   2124: are set to -1.
                   2125: .P
                   2126: Offset values that correspond to unused subpatterns at the end of the
                   2127: expression are also set to -1. For example, if the string "abc" is matched
                   2128: against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The
                   2129: return from the function is 2, because the highest used capturing subpattern
                   2130: number is 1, and the offsets for for the second and third capturing subpatterns
                   2131: (assuming the vector is large enough, of course) are set to -1.
                   2132: .P
                   2133: \fBNote\fP: Elements in the first two-thirds of \fIovector\fP that do not
                   2134: correspond to capturing parentheses in the pattern are never changed. That is,
                   2135: if a pattern contains \fIn\fP capturing parentheses, no more than
                   2136: \fIovector[0]\fP to \fIovector[2n+1]\fP are set by \fBpcre_exec()\fP. The other
                   2137: elements (in the first two-thirds) retain whatever values they previously had.
                   2138: .P
                   2139: Some convenience functions are provided for extracting the captured substrings
                   2140: as separate strings. These are described below.
                   2141: .
                   2142: .
                   2143: .\" HTML <a name="errorlist"></a>
                   2144: .SS "Error return values from \fBpcre_exec()\fP"
                   2145: .rs
                   2146: .sp
                   2147: If \fBpcre_exec()\fP fails, it returns a negative number. The following are
                   2148: defined in the header file:
                   2149: .sp
                   2150:   PCRE_ERROR_NOMATCH        (-1)
                   2151: .sp
                   2152: The subject string did not match the pattern.
                   2153: .sp
                   2154:   PCRE_ERROR_NULL           (-2)
                   2155: .sp
                   2156: Either \fIcode\fP or \fIsubject\fP was passed as NULL, or \fIovector\fP was
                   2157: NULL and \fIovecsize\fP was not zero.
                   2158: .sp
                   2159:   PCRE_ERROR_BADOPTION      (-3)
                   2160: .sp
                   2161: An unrecognized bit was set in the \fIoptions\fP argument.
                   2162: .sp
                   2163:   PCRE_ERROR_BADMAGIC       (-4)
                   2164: .sp
                   2165: PCRE stores a 4-byte "magic number" at the start of the compiled code, to catch
                   2166: the case when it is passed a junk pointer and to detect when a pattern that was
                   2167: compiled in an environment of one endianness is run in an environment with the
                   2168: other endianness. This is the error that PCRE gives when the magic number is
                   2169: not present.
                   2170: .sp
                   2171:   PCRE_ERROR_UNKNOWN_OPCODE (-5)
                   2172: .sp
                   2173: While running the pattern match, an unknown item was encountered in the
                   2174: compiled pattern. This error could be caused by a bug in PCRE or by overwriting
                   2175: of the compiled pattern.
                   2176: .sp
                   2177:   PCRE_ERROR_NOMEMORY       (-6)
                   2178: .sp
                   2179: If a pattern contains back references, but the \fIovector\fP that is passed to
                   2180: \fBpcre_exec()\fP is not big enough to remember the referenced substrings, PCRE
                   2181: gets a block of memory at the start of matching to use for this purpose. If the
                   2182: call via \fBpcre_malloc()\fP fails, this error is given. The memory is
                   2183: automatically freed at the end of matching.
                   2184: .P
                   2185: This error is also given if \fBpcre_stack_malloc()\fP fails in
                   2186: \fBpcre_exec()\fP. This can happen only when PCRE has been compiled with
                   2187: \fB--disable-stack-for-recursion\fP.
                   2188: .sp
                   2189:   PCRE_ERROR_NOSUBSTRING    (-7)
                   2190: .sp
                   2191: This error is used by the \fBpcre_copy_substring()\fP,
                   2192: \fBpcre_get_substring()\fP, and \fBpcre_get_substring_list()\fP functions (see
                   2193: below). It is never returned by \fBpcre_exec()\fP.
                   2194: .sp
                   2195:   PCRE_ERROR_MATCHLIMIT     (-8)
                   2196: .sp
                   2197: The backtracking limit, as specified by the \fImatch_limit\fP field in a
                   2198: \fBpcre_extra\fP structure (or defaulted) was reached. See the description
                   2199: above.
                   2200: .sp
                   2201:   PCRE_ERROR_CALLOUT        (-9)
                   2202: .sp
                   2203: This error is never generated by \fBpcre_exec()\fP itself. It is provided for
                   2204: use by callout functions that want to yield a distinctive error code. See the
                   2205: .\" HREF
                   2206: \fBpcrecallout\fP
                   2207: .\"
                   2208: documentation for details.
                   2209: .sp
                   2210:   PCRE_ERROR_BADUTF8        (-10)
                   2211: .sp
                   2212: A string that contains an invalid UTF-8 byte sequence was passed as a subject,
                   2213: and the PCRE_NO_UTF8_CHECK option was not set. If the size of the output vector
                   2214: (\fIovecsize\fP) is at least 2, the byte offset to the start of the the invalid
                   2215: UTF-8 character is placed in the first element, and a reason code is placed in
                   2216: the second element. The reason codes are listed in the
                   2217: .\" HTML <a href="#badutf8reasons">
                   2218: .\" </a>
                   2219: following section.
                   2220: .\"
                   2221: For backward compatibility, if PCRE_PARTIAL_HARD is set and the problem is a
                   2222: truncated UTF-8 character at the end of the subject (reason codes 1 to 5),
                   2223: PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8.
                   2224: .sp
                   2225:   PCRE_ERROR_BADUTF8_OFFSET (-11)
                   2226: .sp
                   2227: The UTF-8 byte sequence that was passed as a subject was checked and found to
                   2228: be valid (the PCRE_NO_UTF8_CHECK option was not set), but the value of
                   2229: \fIstartoffset\fP did not point to the beginning of a UTF-8 character or the
                   2230: end of the subject.
                   2231: .sp
                   2232:   PCRE_ERROR_PARTIAL        (-12)
                   2233: .sp
                   2234: The subject string did not match, but it did match partially. See the
                   2235: .\" HREF
                   2236: \fBpcrepartial\fP
                   2237: .\"
                   2238: documentation for details of partial matching.
                   2239: .sp
                   2240:   PCRE_ERROR_BADPARTIAL     (-13)
                   2241: .sp
                   2242: This code is no longer in use. It was formerly returned when the PCRE_PARTIAL
                   2243: option was used with a compiled pattern containing items that were not
                   2244: supported for partial matching. From release 8.00 onwards, there are no
                   2245: restrictions on partial matching.
                   2246: .sp
                   2247:   PCRE_ERROR_INTERNAL       (-14)
                   2248: .sp
                   2249: An unexpected internal error has occurred. This error could be caused by a bug
                   2250: in PCRE or by overwriting of the compiled pattern.
                   2251: .sp
                   2252:   PCRE_ERROR_BADCOUNT       (-15)
                   2253: .sp
                   2254: This error is given if the value of the \fIovecsize\fP argument is negative.
                   2255: .sp
                   2256:   PCRE_ERROR_RECURSIONLIMIT (-21)
                   2257: .sp
                   2258: The internal recursion limit, as specified by the \fImatch_limit_recursion\fP
                   2259: field in a \fBpcre_extra\fP structure (or defaulted) was reached. See the
                   2260: description above.
                   2261: .sp
                   2262:   PCRE_ERROR_BADNEWLINE     (-23)
                   2263: .sp
                   2264: An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.
                   2265: .sp
                   2266:   PCRE_ERROR_BADOFFSET      (-24)
                   2267: .sp
                   2268: The value of \fIstartoffset\fP was negative or greater than the length of the
                   2269: subject, that is, the value in \fIlength\fP.
                   2270: .sp
                   2271:   PCRE_ERROR_SHORTUTF8      (-25)
                   2272: .sp
                   2273: This error is returned instead of PCRE_ERROR_BADUTF8 when the subject string
                   2274: ends with a truncated UTF-8 character and the PCRE_PARTIAL_HARD option is set.
                   2275: Information about the failure is returned as for PCRE_ERROR_BADUTF8. It is in
                   2276: fact sufficient to detect this case, but this special error code for
                   2277: PCRE_PARTIAL_HARD precedes the implementation of returned information; it is
                   2278: retained for backwards compatibility.
                   2279: .sp
                   2280:   PCRE_ERROR_RECURSELOOP    (-26)
                   2281: .sp
                   2282: This error is returned when \fBpcre_exec()\fP detects a recursion loop within
                   2283: the pattern. Specifically, it means that either the whole pattern or a
                   2284: subpattern has been called recursively for the second time at the same position
                   2285: in the subject string. Some simple patterns that might do this are detected and
                   2286: faulted at compile time, but more complicated cases, in particular mutual
                   2287: recursions between two different subpatterns, cannot be detected until run
                   2288: time.
                   2289: .sp
                   2290:   PCRE_ERROR_JIT_STACKLIMIT (-27)
                   2291: .sp
1.1.1.3   misho    2292: This error is returned when a pattern that was successfully studied using a
                   2293: JIT compile option is being matched, but the memory available for the
                   2294: just-in-time processing stack is not large enough. See the
1.1       misho    2295: .\" HREF
                   2296: \fBpcrejit\fP
                   2297: .\"
                   2298: documentation for more details.
1.1.1.2   misho    2299: .sp
1.1.1.3   misho    2300:   PCRE_ERROR_BADMODE        (-28)
1.1.1.2   misho    2301: .sp
                   2302: This error is given if a pattern that was compiled by the 8-bit library is
1.1.1.4 ! misho    2303: passed to a 16-bit or 32-bit library function, or vice versa.
1.1.1.2   misho    2304: .sp
1.1.1.3   misho    2305:   PCRE_ERROR_BADENDIANNESS  (-29)
1.1.1.2   misho    2306: .sp
                   2307: This error is given if a pattern that was compiled and saved is reloaded on a
                   2308: host with different endianness. The utility function
                   2309: \fBpcre_pattern_to_host_byte_order()\fP can be used to convert such a pattern
                   2310: so that it runs on the new host.
1.1.1.4 ! misho    2311: .sp
        !          2312:   PCRE_ERROR_JIT_BADOPTION
        !          2313: .sp
        !          2314: This error is returned when a pattern that was successfully studied using a JIT
        !          2315: compile option is being matched, but the matching mode (partial or complete
        !          2316: match) does not correspond to any JIT compilation mode. When the JIT fast path
        !          2317: function is used, this error may be also given for invalid options. See the
        !          2318: .\" HREF
        !          2319: \fBpcrejit\fP
        !          2320: .\"
        !          2321: documentation for more details.
        !          2322: .sp
        !          2323:   PCRE_ERROR_BADLENGTH      (-32)
        !          2324: .sp
        !          2325: This error is given if \fBpcre_exec()\fP is called with a negative value for
        !          2326: the \fIlength\fP argument.
1.1       misho    2327: .P
1.1.1.4 ! misho    2328: Error numbers -16 to -20, -22, and 30 are not used by \fBpcre_exec()\fP.
1.1       misho    2329: .
                   2330: .
                   2331: .\" HTML <a name="badutf8reasons"></a>
                   2332: .SS "Reason codes for invalid UTF-8 strings"
                   2333: .rs
                   2334: .sp
1.1.1.2   misho    2335: This section applies only to the 8-bit library. The corresponding information
1.1.1.4 ! misho    2336: for the 16-bit and 32-bit libraries is given in the
1.1.1.2   misho    2337: .\" HREF
                   2338: \fBpcre16\fP
                   2339: .\"
1.1.1.4 ! misho    2340: and
        !          2341: .\" HREF
        !          2342: \fBpcre32\fP
        !          2343: .\"
        !          2344: pages.
1.1.1.2   misho    2345: .P
1.1       misho    2346: When \fBpcre_exec()\fP returns either PCRE_ERROR_BADUTF8 or
                   2347: PCRE_ERROR_SHORTUTF8, and the size of the output vector (\fIovecsize\fP) is at
                   2348: least 2, the offset of the start of the invalid UTF-8 character is placed in
                   2349: the first output vector element (\fIovector[0]\fP) and a reason code is placed
                   2350: in the second element (\fIovector[1]\fP). The reason codes are given names in
                   2351: the \fBpcre.h\fP header file:
                   2352: .sp
                   2353:   PCRE_UTF8_ERR1
                   2354:   PCRE_UTF8_ERR2
                   2355:   PCRE_UTF8_ERR3
                   2356:   PCRE_UTF8_ERR4
                   2357:   PCRE_UTF8_ERR5
                   2358: .sp
                   2359: The string ends with a truncated UTF-8 character; the code specifies how many
                   2360: bytes are missing (1 to 5). Although RFC 3629 restricts UTF-8 characters to be
                   2361: no longer than 4 bytes, the encoding scheme (originally defined by RFC 2279)
                   2362: allows for up to 6 bytes, and this is checked first; hence the possibility of
                   2363: 4 or 5 missing bytes.
                   2364: .sp
                   2365:   PCRE_UTF8_ERR6
                   2366:   PCRE_UTF8_ERR7
                   2367:   PCRE_UTF8_ERR8
                   2368:   PCRE_UTF8_ERR9
                   2369:   PCRE_UTF8_ERR10
                   2370: .sp
                   2371: The two most significant bits of the 2nd, 3rd, 4th, 5th, or 6th byte of the
                   2372: character do not have the binary value 0b10 (that is, either the most
                   2373: significant bit is 0, or the next bit is 1).
                   2374: .sp
                   2375:   PCRE_UTF8_ERR11
                   2376:   PCRE_UTF8_ERR12
                   2377: .sp
                   2378: A character that is valid by the RFC 2279 rules is either 5 or 6 bytes long;
                   2379: these code points are excluded by RFC 3629.
                   2380: .sp
                   2381:   PCRE_UTF8_ERR13
                   2382: .sp
                   2383: A 4-byte character has a value greater than 0x10fff; these code points are
                   2384: excluded by RFC 3629.
                   2385: .sp
                   2386:   PCRE_UTF8_ERR14
                   2387: .sp
                   2388: A 3-byte character has a value in the range 0xd800 to 0xdfff; this range of
                   2389: code points are reserved by RFC 3629 for use with UTF-16, and so are excluded
                   2390: from UTF-8.
                   2391: .sp
                   2392:   PCRE_UTF8_ERR15
                   2393:   PCRE_UTF8_ERR16
                   2394:   PCRE_UTF8_ERR17
                   2395:   PCRE_UTF8_ERR18
                   2396:   PCRE_UTF8_ERR19
                   2397: .sp
                   2398: A 2-, 3-, 4-, 5-, or 6-byte character is "overlong", that is, it codes for a
                   2399: value that can be represented by fewer bytes, which is invalid. For example,
                   2400: the two bytes 0xc0, 0xae give the value 0x2e, whose correct coding uses just
                   2401: one byte.
                   2402: .sp
                   2403:   PCRE_UTF8_ERR20
                   2404: .sp
                   2405: The two most significant bits of the first byte of a character have the binary
                   2406: value 0b10 (that is, the most significant bit is 1 and the second is 0). Such a
                   2407: byte can only validly occur as the second or subsequent byte of a multi-byte
                   2408: character.
                   2409: .sp
                   2410:   PCRE_UTF8_ERR21
                   2411: .sp
                   2412: The first byte of a character has the value 0xfe or 0xff. These values can
                   2413: never occur in a valid UTF-8 string.
1.1.1.4 ! misho    2414: .sp
        !          2415:   PCRE_UTF8_ERR22
        !          2416: .sp
        !          2417: This error code was formerly used when the presence of a so-called
        !          2418: "non-character" caused an error. Unicode corrigendum #9 makes it clear that
        !          2419: such characters should not cause a string to be rejected, and so this code is
        !          2420: no longer in use and is never returned.
1.1       misho    2421: .
                   2422: .
                   2423: .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"
                   2424: .rs
                   2425: .sp
                   2426: .B int pcre_copy_substring(const char *\fIsubject\fP, int *\fIovector\fP,
                   2427: .ti +5n
                   2428: .B int \fIstringcount\fP, int \fIstringnumber\fP, char *\fIbuffer\fP,
                   2429: .ti +5n
                   2430: .B int \fIbuffersize\fP);
                   2431: .PP
                   2432: .B int pcre_get_substring(const char *\fIsubject\fP, int *\fIovector\fP,
                   2433: .ti +5n
                   2434: .B int \fIstringcount\fP, int \fIstringnumber\fP,
                   2435: .ti +5n
                   2436: .B const char **\fIstringptr\fP);
                   2437: .PP
                   2438: .B int pcre_get_substring_list(const char *\fIsubject\fP,
                   2439: .ti +5n
                   2440: .B int *\fIovector\fP, int \fIstringcount\fP, "const char ***\fIlistptr\fP);"
                   2441: .PP
                   2442: Captured substrings can be accessed directly by using the offsets returned by
                   2443: \fBpcre_exec()\fP in \fIovector\fP. For convenience, the functions
                   2444: \fBpcre_copy_substring()\fP, \fBpcre_get_substring()\fP, and
                   2445: \fBpcre_get_substring_list()\fP are provided for extracting captured substrings
                   2446: as new, separate, zero-terminated strings. These functions identify substrings
                   2447: by number. The next section describes functions for extracting named
                   2448: substrings.
                   2449: .P
                   2450: A substring that contains a binary zero is correctly extracted and has a
                   2451: further zero added on the end, but the result is not, of course, a C string.
                   2452: However, you can process such a string by referring to the length that is
                   2453: returned by \fBpcre_copy_substring()\fP and \fBpcre_get_substring()\fP.
                   2454: Unfortunately, the interface to \fBpcre_get_substring_list()\fP is not adequate
                   2455: for handling strings containing binary zeros, because the end of the final
                   2456: string is not independently indicated.
                   2457: .P
                   2458: The first three arguments are the same for all three of these functions:
                   2459: \fIsubject\fP is the subject string that has just been successfully matched,
                   2460: \fIovector\fP is a pointer to the vector of integer offsets that was passed to
                   2461: \fBpcre_exec()\fP, and \fIstringcount\fP is the number of substrings that were
                   2462: captured by the match, including the substring that matched the entire regular
                   2463: expression. This is the value returned by \fBpcre_exec()\fP if it is greater
                   2464: than zero. If \fBpcre_exec()\fP returned zero, indicating that it ran out of
                   2465: space in \fIovector\fP, the value passed as \fIstringcount\fP should be the
                   2466: number of elements in the vector divided by three.
                   2467: .P
                   2468: The functions \fBpcre_copy_substring()\fP and \fBpcre_get_substring()\fP
                   2469: extract a single substring, whose number is given as \fIstringnumber\fP. A
                   2470: value of zero extracts the substring that matched the entire pattern, whereas
                   2471: higher values extract the captured substrings. For \fBpcre_copy_substring()\fP,
                   2472: the string is placed in \fIbuffer\fP, whose length is given by
                   2473: \fIbuffersize\fP, while for \fBpcre_get_substring()\fP a new block of memory is
                   2474: obtained via \fBpcre_malloc\fP, and its address is returned via
                   2475: \fIstringptr\fP. The yield of the function is the length of the string, not
                   2476: including the terminating zero, or one of these error codes:
                   2477: .sp
                   2478:   PCRE_ERROR_NOMEMORY       (-6)
                   2479: .sp
                   2480: The buffer was too small for \fBpcre_copy_substring()\fP, or the attempt to get
                   2481: memory failed for \fBpcre_get_substring()\fP.
                   2482: .sp
                   2483:   PCRE_ERROR_NOSUBSTRING    (-7)
                   2484: .sp
                   2485: There is no substring whose number is \fIstringnumber\fP.
                   2486: .P
                   2487: The \fBpcre_get_substring_list()\fP function extracts all available substrings
                   2488: and builds a list of pointers to them. All this is done in a single block of
                   2489: memory that is obtained via \fBpcre_malloc\fP. The address of the memory block
                   2490: is returned via \fIlistptr\fP, which is also the start of the list of string
                   2491: pointers. The end of the list is marked by a NULL pointer. The yield of the
                   2492: function is zero if all went well, or the error code
                   2493: .sp
                   2494:   PCRE_ERROR_NOMEMORY       (-6)
                   2495: .sp
                   2496: if the attempt to get the memory block failed.
                   2497: .P
                   2498: When any of these functions encounter a substring that is unset, which can
                   2499: happen when capturing subpattern number \fIn+1\fP matches some part of the
                   2500: subject, but subpattern \fIn\fP has not been used at all, they return an empty
                   2501: string. This can be distinguished from a genuine zero-length substring by
                   2502: inspecting the appropriate offset in \fIovector\fP, which is negative for unset
                   2503: substrings.
                   2504: .P
                   2505: The two convenience functions \fBpcre_free_substring()\fP and
                   2506: \fBpcre_free_substring_list()\fP can be used to free the memory returned by
                   2507: a previous call of \fBpcre_get_substring()\fP or
                   2508: \fBpcre_get_substring_list()\fP, respectively. They do nothing more than call
                   2509: the function pointed to by \fBpcre_free\fP, which of course could be called
                   2510: directly from a C program. However, PCRE is used in some situations where it is
                   2511: linked via a special interface to another programming language that cannot use
                   2512: \fBpcre_free\fP directly; it is for these cases that the functions are
                   2513: provided.
                   2514: .
                   2515: .
                   2516: .SH "EXTRACTING CAPTURED SUBSTRINGS BY NAME"
                   2517: .rs
                   2518: .sp
                   2519: .B int pcre_get_stringnumber(const pcre *\fIcode\fP,
                   2520: .ti +5n
                   2521: .B const char *\fIname\fP);
                   2522: .PP
                   2523: .B int pcre_copy_named_substring(const pcre *\fIcode\fP,
                   2524: .ti +5n
                   2525: .B const char *\fIsubject\fP, int *\fIovector\fP,
                   2526: .ti +5n
                   2527: .B int \fIstringcount\fP, const char *\fIstringname\fP,
                   2528: .ti +5n
                   2529: .B char *\fIbuffer\fP, int \fIbuffersize\fP);
                   2530: .PP
                   2531: .B int pcre_get_named_substring(const pcre *\fIcode\fP,
                   2532: .ti +5n
                   2533: .B const char *\fIsubject\fP, int *\fIovector\fP,
                   2534: .ti +5n
                   2535: .B int \fIstringcount\fP, const char *\fIstringname\fP,
                   2536: .ti +5n
                   2537: .B const char **\fIstringptr\fP);
                   2538: .PP
                   2539: To extract a substring by name, you first have to find associated number.
                   2540: For example, for this pattern
                   2541: .sp
                   2542:   (a+)b(?<xxx>\ed+)...
                   2543: .sp
                   2544: the number of the subpattern called "xxx" is 2. If the name is known to be
                   2545: unique (PCRE_DUPNAMES was not set), you can find the number from the name by
                   2546: calling \fBpcre_get_stringnumber()\fP. The first argument is the compiled
                   2547: pattern, and the second is the name. The yield of the function is the
                   2548: subpattern number, or PCRE_ERROR_NOSUBSTRING (-7) if there is no subpattern of
                   2549: that name.
                   2550: .P
                   2551: Given the number, you can extract the substring directly, or use one of the
                   2552: functions described in the previous section. For convenience, there are also
                   2553: two functions that do the whole job.
                   2554: .P
                   2555: Most of the arguments of \fBpcre_copy_named_substring()\fP and
                   2556: \fBpcre_get_named_substring()\fP are the same as those for the similarly named
                   2557: functions that extract by number. As these are described in the previous
                   2558: section, they are not re-described here. There are just two differences:
                   2559: .P
                   2560: First, instead of a substring number, a substring name is given. Second, there
                   2561: is an extra argument, given at the start, which is a pointer to the compiled
                   2562: pattern. This is needed in order to gain access to the name-to-number
                   2563: translation table.
                   2564: .P
                   2565: These functions call \fBpcre_get_stringnumber()\fP, and if it succeeds, they
                   2566: then call \fBpcre_copy_substring()\fP or \fBpcre_get_substring()\fP, as
                   2567: appropriate. \fBNOTE:\fP If PCRE_DUPNAMES is set and there are duplicate names,
                   2568: the behaviour may not be what you want (see the next section).
                   2569: .P
                   2570: \fBWarning:\fP If the pattern uses the (?| feature to set up multiple
                   2571: subpatterns with the same number, as described in the
                   2572: .\" HTML <a href="pcrepattern.html#dupsubpatternnumber">
                   2573: .\" </a>
                   2574: section on duplicate subpattern numbers
                   2575: .\"
                   2576: in the
                   2577: .\" HREF
                   2578: \fBpcrepattern\fP
                   2579: .\"
                   2580: page, you cannot use names to distinguish the different subpatterns, because
                   2581: names are not included in the compiled code. The matching process uses only
                   2582: numbers. For this reason, the use of different names for subpatterns of the
                   2583: same number causes an error at compile time.
                   2584: .
                   2585: .
                   2586: .SH "DUPLICATE SUBPATTERN NAMES"
                   2587: .rs
                   2588: .sp
                   2589: .B int pcre_get_stringtable_entries(const pcre *\fIcode\fP,
                   2590: .ti +5n
                   2591: .B const char *\fIname\fP, char **\fIfirst\fP, char **\fIlast\fP);
                   2592: .PP
                   2593: When a pattern is compiled with the PCRE_DUPNAMES option, names for subpatterns
                   2594: are not required to be unique. (Duplicate names are always allowed for
                   2595: subpatterns with the same number, created by using the (?| feature. Indeed, if
                   2596: such subpatterns are named, they are required to use the same names.)
                   2597: .P
                   2598: Normally, patterns with duplicate names are such that in any one match, only
                   2599: one of the named subpatterns participates. An example is shown in the
                   2600: .\" HREF
                   2601: \fBpcrepattern\fP
                   2602: .\"
                   2603: documentation.
                   2604: .P
                   2605: When duplicates are present, \fBpcre_copy_named_substring()\fP and
                   2606: \fBpcre_get_named_substring()\fP return the first substring corresponding to
                   2607: the given name that is set. If none are set, PCRE_ERROR_NOSUBSTRING (-7) is
                   2608: returned; no data is returned. The \fBpcre_get_stringnumber()\fP function
                   2609: returns one of the numbers that are associated with the name, but it is not
                   2610: defined which it is.
                   2611: .P
                   2612: If you want to get full details of all captured substrings for a given name,
                   2613: you must use the \fBpcre_get_stringtable_entries()\fP function. The first
                   2614: argument is the compiled pattern, and the second is the name. The third and
                   2615: fourth are pointers to variables which are updated by the function. After it
                   2616: has run, they point to the first and last entries in the name-to-number table
                   2617: for the given name. The function itself returns the length of each entry, or
                   2618: PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is
                   2619: described above in the section entitled \fIInformation about a pattern\fP
                   2620: .\" HTML <a href="#infoaboutpattern">
                   2621: .\" </a>
                   2622: above.
                   2623: .\"
                   2624: Given all the relevant entries for the name, you can extract each of their
                   2625: numbers, and hence the captured data, if any.
                   2626: .
                   2627: .
                   2628: .SH "FINDING ALL POSSIBLE MATCHES"
                   2629: .rs
                   2630: .sp
                   2631: The traditional matching function uses a similar algorithm to Perl, which stops
                   2632: when it finds the first match, starting at a given point in the subject. If you
                   2633: want to find all possible matches, or the longest possible match, consider
                   2634: using the alternative matching function (see below) instead. If you cannot use
                   2635: the alternative function, but still need to find all possible matches, you
                   2636: can kludge it up by making use of the callout facility, which is described in
                   2637: the
                   2638: .\" HREF
                   2639: \fBpcrecallout\fP
                   2640: .\"
                   2641: documentation.
                   2642: .P
                   2643: What you have to do is to insert a callout right at the end of the pattern.
                   2644: When your callout function is called, extract and save the current matched
                   2645: substring. Then return 1, which forces \fBpcre_exec()\fP to backtrack and try
                   2646: other alternatives. Ultimately, when it runs out of matches, \fBpcre_exec()\fP
                   2647: will yield PCRE_ERROR_NOMATCH.
                   2648: .
                   2649: .
1.1.1.2   misho    2650: .SH "OBTAINING AN ESTIMATE OF STACK USAGE"
                   2651: .rs
                   2652: .sp
                   2653: Matching certain patterns using \fBpcre_exec()\fP can use a lot of process
                   2654: stack, which in certain environments can be rather limited in size. Some users
                   2655: find it helpful to have an estimate of the amount of stack that is used by
                   2656: \fBpcre_exec()\fP, to help them set recursion limits, as described in the
                   2657: .\" HREF
                   2658: \fBpcrestack\fP
                   2659: .\"
                   2660: documentation. The estimate that is output by \fBpcretest\fP when called with
                   2661: the \fB-m\fP and \fB-C\fP options is obtained by calling \fBpcre_exec\fP with
                   2662: the values NULL, NULL, NULL, -999, and -999 for its first five arguments.
                   2663: .P
                   2664: Normally, if its first argument is NULL, \fBpcre_exec()\fP immediately returns
                   2665: the negative error code PCRE_ERROR_NULL, but with this special combination of
                   2666: arguments, it returns instead a negative number whose absolute value is the
                   2667: approximate stack frame size in bytes. (A negative number is used so that it is
                   2668: clear that no match has happened.) The value is approximate because in some
                   2669: cases, recursive calls to \fBpcre_exec()\fP occur when there are one or two
                   2670: additional variables on the stack.
                   2671: .P
                   2672: If PCRE has been compiled to use the heap instead of the stack for recursion,
                   2673: the value returned is the size of each block that is obtained from the heap.
                   2674: .
                   2675: .
1.1       misho    2676: .\" HTML <a name="dfamatch"></a>
                   2677: .SH "MATCHING A PATTERN: THE ALTERNATIVE FUNCTION"
                   2678: .rs
                   2679: .sp
                   2680: .B int pcre_dfa_exec(const pcre *\fIcode\fP, "const pcre_extra *\fIextra\fP,"
                   2681: .ti +5n
                   2682: .B "const char *\fIsubject\fP," int \fIlength\fP, int \fIstartoffset\fP,
                   2683: .ti +5n
                   2684: .B int \fIoptions\fP, int *\fIovector\fP, int \fIovecsize\fP,
                   2685: .ti +5n
                   2686: .B int *\fIworkspace\fP, int \fIwscount\fP);
                   2687: .P
                   2688: The function \fBpcre_dfa_exec()\fP is called to match a subject string against
                   2689: a compiled pattern, using a matching algorithm that scans the subject string
                   2690: just once, and does not backtrack. This has different characteristics to the
                   2691: normal algorithm, and is not compatible with Perl. Some of the features of PCRE
                   2692: patterns are not supported. Nevertheless, there are times when this kind of
                   2693: matching can be useful. For a discussion of the two matching algorithms, and a
                   2694: list of features that \fBpcre_dfa_exec()\fP does not support, see the
                   2695: .\" HREF
                   2696: \fBpcrematching\fP
                   2697: .\"
                   2698: documentation.
                   2699: .P
                   2700: The arguments for the \fBpcre_dfa_exec()\fP function are the same as for
                   2701: \fBpcre_exec()\fP, plus two extras. The \fIovector\fP argument is used in a
                   2702: different way, and this is described below. The other common arguments are used
                   2703: in the same way as for \fBpcre_exec()\fP, so their description is not repeated
                   2704: here.
                   2705: .P
                   2706: The two additional arguments provide workspace for the function. The workspace
                   2707: vector should contain at least 20 elements. It is used for keeping track of
                   2708: multiple paths through the pattern tree. More workspace will be needed for
                   2709: patterns and subjects where there are a lot of potential matches.
                   2710: .P
                   2711: Here is an example of a simple call to \fBpcre_dfa_exec()\fP:
                   2712: .sp
                   2713:   int rc;
                   2714:   int ovector[10];
                   2715:   int wspace[20];
                   2716:   rc = pcre_dfa_exec(
                   2717:     re,             /* result of pcre_compile() */
                   2718:     NULL,           /* we didn't study the pattern */
                   2719:     "some string",  /* the subject string */
                   2720:     11,             /* the length of the subject string */
                   2721:     0,              /* start at offset 0 in the subject */
                   2722:     0,              /* default options */
                   2723:     ovector,        /* vector of integers for substring information */
                   2724:     10,             /* number of elements (NOT size in bytes) */
                   2725:     wspace,         /* working space vector */
                   2726:     20);            /* number of elements (NOT size in bytes) */
                   2727: .
                   2728: .SS "Option bits for \fBpcre_dfa_exec()\fP"
                   2729: .rs
                   2730: .sp
                   2731: The unused bits of the \fIoptions\fP argument for \fBpcre_dfa_exec()\fP must be
                   2732: zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_\fIxxx\fP,
                   2733: PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
                   2734: PCRE_NO_UTF8_CHECK, PCRE_BSR_ANYCRLF, PCRE_BSR_UNICODE, PCRE_NO_START_OPTIMIZE,
                   2735: PCRE_PARTIAL_HARD, PCRE_PARTIAL_SOFT, PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART.
                   2736: All but the last four of these are exactly the same as for \fBpcre_exec()\fP,
                   2737: so their description is not repeated here.
                   2738: .sp
                   2739:   PCRE_PARTIAL_HARD
                   2740:   PCRE_PARTIAL_SOFT
                   2741: .sp
                   2742: These have the same general effect as they do for \fBpcre_exec()\fP, but the
                   2743: details are slightly different. When PCRE_PARTIAL_HARD is set for
                   2744: \fBpcre_dfa_exec()\fP, it returns PCRE_ERROR_PARTIAL if the end of the subject
                   2745: is reached and there is still at least one matching possibility that requires
                   2746: additional characters. This happens even if some complete matches have also
                   2747: been found. When PCRE_PARTIAL_SOFT is set, the return code PCRE_ERROR_NOMATCH
                   2748: is converted into PCRE_ERROR_PARTIAL if the end of the subject is reached,
                   2749: there have been no complete matches, but there is still at least one matching
                   2750: possibility. The portion of the string that was inspected when the longest
                   2751: partial match was found is set as the first matching string in both cases.
                   2752: There is a more detailed discussion of partial and multi-segment matching, with
                   2753: examples, in the
                   2754: .\" HREF
                   2755: \fBpcrepartial\fP
                   2756: .\"
                   2757: documentation.
                   2758: .sp
                   2759:   PCRE_DFA_SHORTEST
                   2760: .sp
                   2761: Setting the PCRE_DFA_SHORTEST option causes the matching algorithm to stop as
                   2762: soon as it has found one match. Because of the way the alternative algorithm
                   2763: works, this is necessarily the shortest possible match at the first possible
                   2764: matching point in the subject string.
                   2765: .sp
                   2766:   PCRE_DFA_RESTART
                   2767: .sp
                   2768: When \fBpcre_dfa_exec()\fP returns a partial match, it is possible to call it
                   2769: again, with additional subject characters, and have it continue with the same
                   2770: match. The PCRE_DFA_RESTART option requests this action; when it is set, the
                   2771: \fIworkspace\fP and \fIwscount\fP options must reference the same vector as
                   2772: before because data about the match so far is left in them after a partial
                   2773: match. There is more discussion of this facility in the
                   2774: .\" HREF
                   2775: \fBpcrepartial\fP
                   2776: .\"
                   2777: documentation.
                   2778: .
                   2779: .
                   2780: .SS "Successful returns from \fBpcre_dfa_exec()\fP"
                   2781: .rs
                   2782: .sp
                   2783: When \fBpcre_dfa_exec()\fP succeeds, it may have matched more than one
                   2784: substring in the subject. Note, however, that all the matches from one run of
                   2785: the function start at the same point in the subject. The shorter matches are
                   2786: all initial substrings of the longer matches. For example, if the pattern
                   2787: .sp
                   2788:   <.*>
                   2789: .sp
                   2790: is matched against the string
                   2791: .sp
                   2792:   This is <something> <something else> <something further> no more
                   2793: .sp
                   2794: the three matched strings are
                   2795: .sp
                   2796:   <something>
                   2797:   <something> <something else>
                   2798:   <something> <something else> <something further>
                   2799: .sp
                   2800: On success, the yield of the function is a number greater than zero, which is
                   2801: the number of matched substrings. The substrings themselves are returned in
                   2802: \fIovector\fP. Each string uses two elements; the first is the offset to the
                   2803: start, and the second is the offset to the end. In fact, all the strings have
                   2804: the same start offset. (Space could have been saved by giving this only once,
                   2805: but it was decided to retain some compatibility with the way \fBpcre_exec()\fP
                   2806: returns data, even though the meaning of the strings is different.)
                   2807: .P
                   2808: The strings are returned in reverse order of length; that is, the longest
                   2809: matching string is given first. If there were too many matches to fit into
                   2810: \fIovector\fP, the yield of the function is zero, and the vector is filled with
                   2811: the longest matches. Unlike \fBpcre_exec()\fP, \fBpcre_dfa_exec()\fP can use
                   2812: the entire \fIovector\fP for returning matched strings.
                   2813: .
                   2814: .
                   2815: .SS "Error returns from \fBpcre_dfa_exec()\fP"
                   2816: .rs
                   2817: .sp
                   2818: The \fBpcre_dfa_exec()\fP function returns a negative number when it fails.
                   2819: Many of the errors are the same as for \fBpcre_exec()\fP, and these are
                   2820: described
                   2821: .\" HTML <a href="#errorlist">
                   2822: .\" </a>
                   2823: above.
                   2824: .\"
                   2825: There are in addition the following errors that are specific to
                   2826: \fBpcre_dfa_exec()\fP:
                   2827: .sp
                   2828:   PCRE_ERROR_DFA_UITEM      (-16)
                   2829: .sp
                   2830: This return is given if \fBpcre_dfa_exec()\fP encounters an item in the pattern
                   2831: that it does not support, for instance, the use of \eC or a back reference.
                   2832: .sp
                   2833:   PCRE_ERROR_DFA_UCOND      (-17)
                   2834: .sp
                   2835: This return is given if \fBpcre_dfa_exec()\fP encounters a condition item that
                   2836: uses a back reference for the condition, or a test for recursion in a specific
                   2837: group. These are not supported.
                   2838: .sp
                   2839:   PCRE_ERROR_DFA_UMLIMIT    (-18)
                   2840: .sp
                   2841: This return is given if \fBpcre_dfa_exec()\fP is called with an \fIextra\fP
                   2842: block that contains a setting of the \fImatch_limit\fP or
                   2843: \fImatch_limit_recursion\fP fields. This is not supported (these fields are
                   2844: meaningless for DFA matching).
                   2845: .sp
                   2846:   PCRE_ERROR_DFA_WSSIZE     (-19)
                   2847: .sp
                   2848: This return is given if \fBpcre_dfa_exec()\fP runs out of space in the
                   2849: \fIworkspace\fP vector.
                   2850: .sp
                   2851:   PCRE_ERROR_DFA_RECURSE    (-20)
                   2852: .sp
                   2853: When a recursive subpattern is processed, the matching function calls itself
                   2854: recursively, using private vectors for \fIovector\fP and \fIworkspace\fP. This
                   2855: error is given if the output vector is not large enough. This should be
                   2856: extremely rare, as a vector of size 1000 is used.
1.1.1.3   misho    2857: .sp
                   2858:   PCRE_ERROR_DFA_BADRESTART (-30)
                   2859: .sp
                   2860: When \fBpcre_dfa_exec()\fP is called with the \fBPCRE_DFA_RESTART\fP option,
                   2861: some plausibility checks are made on the contents of the workspace, which
                   2862: should contain data about the previous partial match. If any of these checks
                   2863: fail, this error is given.
1.1       misho    2864: .
                   2865: .
                   2866: .SH "SEE ALSO"
                   2867: .rs
                   2868: .sp
1.1.1.4 ! misho    2869: \fBpcre16\fP(3), \fBpcre32\fP(3), \fBpcrebuild\fP(3), \fBpcrecallout\fP(3),
        !          2870: \fBpcrecpp(3)\fP(3), \fBpcrematching\fP(3), \fBpcrepartial\fP(3),
        !          2871: \fBpcreposix\fP(3), \fBpcreprecompile\fP(3), \fBpcresample\fP(3),
        !          2872: \fBpcrestack\fP(3).
1.1       misho    2873: .
                   2874: .
                   2875: .SH AUTHOR
                   2876: .rs
                   2877: .sp
                   2878: .nf
                   2879: Philip Hazel
                   2880: University Computing Service
                   2881: Cambridge CB2 3QH, England.
                   2882: .fi
                   2883: .
                   2884: .
                   2885: .SH REVISION
                   2886: .rs
                   2887: .sp
                   2888: .nf
1.1.1.4 ! misho    2889: Last updated: 12 May 2013
        !          2890: Copyright (c) 1997-2013 University of Cambridge.
1.1       misho    2891: .fi

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