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diff --git a/lib/win32/pcre/doc/pcreposix.3 b/lib/win32/pcre/doc/pcreposix.3 new file mode 100644 index 0000000000..c6092ac529 --- /dev/null +++ b/lib/win32/pcre/doc/pcreposix.3 @@ -0,0 +1,261 @@ +.TH PCREPOSIX 3 +.SH NAME +PCRE - Perl-compatible regular expressions. +.SH "SYNOPSIS OF POSIX API" +.rs +.sp +.B #include <pcreposix.h> +.PP +.SM +.B int regcomp(regex_t *\fIpreg\fP, const char *\fIpattern\fP, +.ti +5n +.B int \fIcflags\fP); +.PP +.B int regexec(regex_t *\fIpreg\fP, const char *\fIstring\fP, +.ti +5n +.B size_t \fInmatch\fP, regmatch_t \fIpmatch\fP[], int \fIeflags\fP); +.PP +.B size_t regerror(int \fIerrcode\fP, const regex_t *\fIpreg\fP, +.ti +5n +.B char *\fIerrbuf\fP, size_t \fIerrbuf_size\fP); +.PP +.B void regfree(regex_t *\fIpreg\fP); +. +.SH DESCRIPTION +.rs +.sp +This set of functions provides a POSIX-style API to the PCRE regular expression +package. See the +.\" HREF +\fBpcreapi\fP +.\" +documentation for a description of PCRE's native API, which contains much +additional functionality. +.P +The functions described here are just wrapper functions that ultimately call +the PCRE native API. Their prototypes are defined in the \fBpcreposix.h\fP +header file, and on Unix systems the library itself is called +\fBpcreposix.a\fP, so can be accessed by adding \fB-lpcreposix\fP to the +command for linking an application that uses them. Because the POSIX functions +call the native ones, it is also necessary to add \fB-lpcre\fP. +.P +I have implemented only those POSIX option bits that can be reasonably mapped +to PCRE native options. In addition, the option REG_EXTENDED is defined with +the value zero. This has no effect, but since programs that are written to the +POSIX interface often use it, this makes it easier to slot in PCRE as a +replacement library. Other POSIX options are not even defined. +.P +There are also some other options that are not defined by POSIX. These have +been added at the request of users who want to make use of certain +PCRE-specific features via the POSIX calling interface. +.P +When PCRE is called via these functions, it is only the API that is POSIX-like +in style. The syntax and semantics of the regular expressions themselves are +still those of Perl, subject to the setting of various PCRE options, as +described below. "POSIX-like in style" means that the API approximates to the +POSIX definition; it is not fully POSIX-compatible, and in multi-byte encoding +domains it is probably even less compatible. +.P +The header for these functions is supplied as \fBpcreposix.h\fP to avoid any +potential clash with other POSIX libraries. It can, of course, be renamed or +aliased as \fBregex.h\fP, which is the "correct" name. It provides two +structure types, \fIregex_t\fP for compiled internal forms, and +\fIregmatch_t\fP for returning captured substrings. It also defines some +constants whose names start with "REG_"; these are used for setting options and +identifying error codes. +.P +.SH "COMPILING A PATTERN" +.rs +.sp +The function \fBregcomp()\fP is called to compile a pattern into an +internal form. The pattern is a C string terminated by a binary zero, and +is passed in the argument \fIpattern\fP. The \fIpreg\fP argument is a pointer +to a \fBregex_t\fP structure that is used as a base for storing information +about the compiled regular expression. +.P +The argument \fIcflags\fP is either zero, or contains one or more of the bits +defined by the following macros: +.sp + REG_DOTALL +.sp +The PCRE_DOTALL option is set when the regular expression is passed for +compilation to the native function. Note that REG_DOTALL is not part of the +POSIX standard. +.sp + REG_ICASE +.sp +The PCRE_CASELESS option is set when the regular expression is passed for +compilation to the native function. +.sp + REG_NEWLINE +.sp +The PCRE_MULTILINE option is set when the regular expression is passed for +compilation to the native function. Note that this does \fInot\fP mimic the +defined POSIX behaviour for REG_NEWLINE (see the following section). +.sp + REG_NOSUB +.sp +The PCRE_NO_AUTO_CAPTURE option is set when the regular expression is passed +for compilation to the native function. In addition, when a pattern that is +compiled with this flag is passed to \fBregexec()\fP for matching, the +\fInmatch\fP and \fIpmatch\fP arguments are ignored, and no captured strings +are returned. +.sp + REG_UNGREEDY +.sp +The PCRE_UNGREEDY option is set when the regular expression is passed for +compilation to the native function. Note that REG_UNGREEDY is not part of the +POSIX standard. +.sp + REG_UTF8 +.sp +The PCRE_UTF8 option is set when the regular expression is passed for +compilation to the native function. This causes the pattern itself and all data +strings used for matching it to be treated as UTF-8 strings. Note that REG_UTF8 +is not part of the POSIX standard. +.P +In the absence of these flags, no options are passed to the native function. +This means the the regex is compiled with PCRE default semantics. In +particular, the way it handles newline characters in the subject string is the +Perl way, not the POSIX way. Note that setting PCRE_MULTILINE has only +\fIsome\fP of the effects specified for REG_NEWLINE. It does not affect the way +newlines are matched by . (they are not) or by a negative class such as [^a] +(they are). +.P +The yield of \fBregcomp()\fP is zero on success, and non-zero otherwise. The +\fIpreg\fP structure is filled in on success, and one member of the structure +is public: \fIre_nsub\fP contains the number of capturing subpatterns in +the regular expression. Various error codes are defined in the header file. +.P +NOTE: If the yield of \fBregcomp()\fP is non-zero, you must not attempt to +use the contents of the \fIpreg\fP structure. If, for example, you pass it to +\fBregexec()\fP, the result is undefined and your program is likely to crash. +. +. +.SH "MATCHING NEWLINE CHARACTERS" +.rs +.sp +This area is not simple, because POSIX and Perl take different views of things. +It is not possible to get PCRE to obey POSIX semantics, but then PCRE was never +intended to be a POSIX engine. The following table lists the different +possibilities for matching newline characters in PCRE: +.sp + Default Change with +.sp + . matches newline no PCRE_DOTALL + newline matches [^a] yes not changeable + $ matches \en at end yes PCRE_DOLLARENDONLY + $ matches \en in middle no PCRE_MULTILINE + ^ matches \en in middle no PCRE_MULTILINE +.sp +This is the equivalent table for POSIX: +.sp + Default Change with +.sp + . matches newline yes REG_NEWLINE + newline matches [^a] yes REG_NEWLINE + $ matches \en at end no REG_NEWLINE + $ matches \en in middle no REG_NEWLINE + ^ matches \en in middle no REG_NEWLINE +.sp +PCRE's behaviour is the same as Perl's, except that there is no equivalent for +PCRE_DOLLAR_ENDONLY in Perl. In both PCRE and Perl, there is no way to stop +newline from matching [^a]. +.P +The default POSIX newline handling can be obtained by setting PCRE_DOTALL and +PCRE_DOLLAR_ENDONLY, but there is no way to make PCRE behave exactly as for the +REG_NEWLINE action. +. +. +.SH "MATCHING A PATTERN" +.rs +.sp +The function \fBregexec()\fP is called to match a compiled pattern \fIpreg\fP +against a given \fIstring\fP, which is by default terminated by a zero byte +(but see REG_STARTEND below), subject to the options in \fIeflags\fP. These can +be: +.sp + REG_NOTBOL +.sp +The PCRE_NOTBOL option is set when calling the underlying PCRE matching +function. +.sp + REG_NOTEMPTY +.sp +The PCRE_NOTEMPTY option is set when calling the underlying PCRE matching +function. Note that REG_NOTEMPTY is not part of the POSIX standard. However, +setting this option can give more POSIX-like behaviour in some situations. +.sp + REG_NOTEOL +.sp +The PCRE_NOTEOL option is set when calling the underlying PCRE matching +function. +.sp + REG_STARTEND +.sp +The string is considered to start at \fIstring\fP + \fIpmatch[0].rm_so\fP and +to have a terminating NUL located at \fIstring\fP + \fIpmatch[0].rm_eo\fP +(there need not actually be a NUL at that location), regardless of the value of +\fInmatch\fP. This is a BSD extension, compatible with but not specified by +IEEE Standard 1003.2 (POSIX.2), and should be used with caution in software +intended to be portable to other systems. Note that a non-zero \fIrm_so\fP does +not imply REG_NOTBOL; REG_STARTEND affects only the location of the string, not +how it is matched. +.P +If the pattern was compiled with the REG_NOSUB flag, no data about any matched +strings is returned. The \fInmatch\fP and \fIpmatch\fP arguments of +\fBregexec()\fP are ignored. +.P +If the value of \fInmatch\fP is zero, or if the value \fIpmatch\fP is NULL, +no data about any matched strings is returned. +.P +Otherwise,the portion of the string that was matched, and also any captured +substrings, are returned via the \fIpmatch\fP argument, which points to an +array of \fInmatch\fP structures of type \fIregmatch_t\fP, containing the +members \fIrm_so\fP and \fIrm_eo\fP. These contain the offset to the first +character of each substring and the offset to the first character after the end +of each substring, respectively. The 0th element of the vector relates to the +entire portion of \fIstring\fP that was matched; subsequent elements relate to +the capturing subpatterns of the regular expression. Unused entries in the +array have both structure members set to -1. +.P +A successful match yields a zero return; various error codes are defined in the +header file, of which REG_NOMATCH is the "expected" failure code. +. +. +.SH "ERROR MESSAGES" +.rs +.sp +The \fBregerror()\fP function maps a non-zero errorcode from either +\fBregcomp()\fP or \fBregexec()\fP to a printable message. If \fIpreg\fP is not +NULL, the error should have arisen from the use of that structure. A message +terminated by a binary zero is placed in \fIerrbuf\fP. The length of the +message, including the zero, is limited to \fIerrbuf_size\fP. The yield of the +function is the size of buffer needed to hold the whole message. +. +. +.SH MEMORY USAGE +.rs +.sp +Compiling a regular expression causes memory to be allocated and associated +with the \fIpreg\fP structure. The function \fBregfree()\fP frees all such +memory, after which \fIpreg\fP may no longer be used as a compiled expression. +. +. +.SH AUTHOR +.rs +.sp +.nf +Philip Hazel +University Computing Service +Cambridge CB2 3QH, England. +.fi +. +. +.SH REVISION +.rs +.sp +.nf +Last updated: 02 September 2009 +Copyright (c) 1997-2009 University of Cambridge. +.fi |