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Text File | 1999-04-23 | 11.6 KB | 255 lines

TABLE OF CONTENTS regex.library/--rexxhost-- regex.library/--structures-- regex.library/regcomp regex.library/regerror regex.library/regexec regex.library/regfree regex.library/--rexxhost-- regex.library/--rexxhost-- HOST INTERFACE regex.library provides an ARexx functions interface, with offset -30, offering to ARexx macro just one funcion, for now, : REMATH Usage: res = rematch(regex,string,flags,pmatch) <regexp>,<string>,[flags],[pmath/V] Verify is regex , a regular expression, matches string , returning 0 on succes or a positive regex error code. The error string can be found in REGERR on failure. If flags is specified, it is one or more of: - ICASE Compile for matching that ignores upper/lower case distinctions. - OLD Compile obsolete (``basic'') REs, rather than the modern (``extended'') REs that are the default. - NEWLINE Compile for newline-sensitive matching. - STARTEND pmatch.SO is the start offset pmatch.EO-1 is the end offset pmatch must be specified If pmatch is specified, the fields: - SO index of the first character that matches - EO index of the character after the last that matches are set. regex.library/--structures-- regex.library/--structures-- STRUCTURES The header <regex.h> declares two structure types: - regex_t - regmatch_t The former for compiled internal forms and the latter for match reporting. It also declares the four functions, a type regoff_t, and a number of constants with names starting with REG_ . regex.library/regcomp regex.library/regcomp NAME regcomp -- compiles a regular expression. SYNOPSIS err = regcomp(preg,pattern,cflags); a0 a1 d0 int regcomp(regex_t *preg, const char *pattern, int cflags); FUNCTION Compiles the regular expression contained in the pattern string, subject to the flags in cflags and places the results in the regex_t structure pointed to by preg . An internal pool in the library base is used to hold any allocated resource. The memory is freed asap. INPUTS preg - a pointer to a regex_t where the regular expression wil be written pattern - the regular expression string Cflags - is the bitwise OR of zero or more of the following flags: REG_EXTENDED Compile modern (``extended'') REs, rather than the obsolete (``basic'') REs that are the default. REG_BASIC This is a synonym for 0, provided as a counterpart to REG_EXTENDED to improve readability. REG_NOSPEC Compile with recognition of all special characters turned off. All characters are thus considered ordinary, so the ``RE'' is a literal string. This is an extension, compatible with but not specified by POSIX 1003.2, and should be used with caution in software intended to be portable to other systems. REG_EXTENDED and REG_NOSPEC may not be used in the same call to regcomp . REG_ICASE Compile for matching that ignores upper/lower case distinctions. REG_NOSUB Compile for matching that need only report success or failure, not what was matched. REG_NEWLINE Compile for newline-sensitive matching. By default, newline is a completely ordinary character with no special meaning in either REs or strings. With this flag, `[^' bracket expressions and `.' never match newline, a `^' anchor matches the null string after any newline in the string in addition to its normal function, and the `$' anchor matches the null string before any newline in the string in addition to its normal function. REG_PEND The regular expression ends, not at the first NUL, but just before the character pointed to by the re_endp member of the structure pointed to by preg . The re_endp member is of type const char * . This flag permits inclusion of NULs in the RE; they are considered ordinary characters. This is an extension, compatible with but not specified by POSIX 1003.2, and should be used with caution in software intended to be portable to other systems. RESULT When successful, regcomp returns 0 and fills in the structure pointed to by preg . One member of that structure (other than re_endp) is publicized: re_nsub , of type size_t , contains the number of parenthesized subexpressions within the RE (except that the value of this member is undefined if the REG_NOSUB flag was used). If regcomp fails, it returns a non-zero error code. regex.library/regerror regex.library/regerror NAME regerror -- maps a non-zero errcode. SYNOPSIS size = regerror(code,preg,errbuf,errsize); a1 d2 d0 d1 size_t regerror(int errcode, const regex_t *preg,char *errbuf, size_t errbuf_size); FUNCTION Maps a non-zero errcode from either regcomp or regexec to a human-readable, printable message. If preg is non-NULL, the error code should have arisen from use of the regex_t pointed to by preg , and if the error code came from regcomp , it should have been the result from the most recent regcomp using that regex_t ( regerror may be able to supply a more detailed message using information from the regex_t ). regerror places the NULL-terminated message into the buffer pointed to by errbuf , limiting the length (including the NULL) to at most errbuf_size bytes. If the whole message won't fit, as much of it as will fit before the terminating NULL is supplied. In any case, the returned value is the size of buffer needed to hold the whole message (including terminating NULL). If errbuf_size is 0, errbuf is ignored but the return value is still correct. INPUT errcode - a regex positive error code preg - a preg or NULL errbuf - a buffer or NULL errbuf_size - size of errbuf RESULT Size to hold the complete error message. regex.library/regexec regex.library/regexec NAME regexec -- matches a RE against a string. SYNOPSI err = regexec(preg,string,nmatch,pmatch[],eflags); a1 d0 d1 d2 d3 int regexec(const regex_t *preg, const char *string, size_t nmatch, regmatch_t pmatch[], int eflags); FUNCTION Matches the compiled RE pointed to by preg against the string , subject to the flags in eflags , and reports results using nmatch , pmatch , and the returned value. The RE must have been compiled by a previous invocation of regcomp . The compiled form is not altered during execution of regexec , so a single compiled RE can be used simultaneously by multiple threads. By default, the NUL-terminated string pointed to by string is considered to be the text of an entire line, minus any terminating newline. The eflags argument is the bitwise OR of zero or more of the following flags: - REG_NOTBOL The first character of the string is not the beginning of a line, so the `^' anchor should not match before it. This does not affect the behavior of newlines under REG_NEWLINE. - REG_NOTEOL The NUL terminating the string does not end a line, so the `$' anchor should not match before it. This does not affect the behavior of newlines under REG_NEWLINE. - REG_STARTEND The string is considered to start at string + pmatch[0].rm_so and to have a terminating NUL located at string + pmatch[0].rm_eo (there need not actually be a NUL at that location), regardless of the value of nmatch . See below for the definition of pmatch and nmatch . This is an extension, compatible with but not specified by POSIX 1003.2, and should be used with caution in software intended to be portable to other systems. Note that a non-zero rm_so does not imply REG_NOTBOL; affects only the location of the string, not how it is matched. Normally, regexec returns 0 for success and the non-zero code REG_NOMATCH for failure. Other non-zero error codes may be returned in exceptional situations. If REG_NOSUB was specified in the compilation of the RE, or if nmatch is 0, regexec ignores the pmatch argument (but see below for the case where REG_STARTEND is specified). Otherwise, pmatch points to an array of nmatch structures of type regmatch_t . Such a structure has at least the members rm_so and rm_eo , both of type regoff_t (a signed arithmetic type at least as large as an off_t and a ssize_t ), containing respectively the offset of the first character of a substring and the offset of the first character after the end of the substring. Offsets are measured from the beginning of the string argument given to regexec . An empty substring is denoted by equal offsets, both indicating the character following the empty substring. The 0th member of the pmatch array is filled in to indicate what substring of string was matched by the entire RE. Remaining members report what substring was matched by parenthesized subexpressions within the RE; member i reports subexpression i , with subexpressions counted (starting at 1) by the order of their opening parentheses in the RE, left to right. Unused entries in the array (corresponding either to subexpressions that did not participate in the match at all, or to subexpressions that do not exist in the RE (that is, i > preg->re_nsub) (have both rm_so and rm_eo set to -1. If a subexpression participated in the match several times, the reported substring is the last one it matched. (Note, as an example in particular, that when the RE `(b*)+' matches `bbb', the parenthesized subexpression matches each of the three `b's and then an infinite number of empty strings following the last `b', so the reported substring is one of the empties.) If REG_STARTEND is specified, pmatch must point to at least one regmatch_t (even if nmatch is 0 or REG_NOSUB was specified), to hold the input offsets for REG_STARTEND. Use for output is still entirely controlled by nmatch ; if nmatch is 0 or REG_NOSUB was specified, the value of pmatch [0] will not be changed by a successful regexec . INPUTS preg - a regular expression pointer nmatch - number of element in pmatch pmatch - holds result eflags - flags RESULT 0 on matching or a positive regex error code. regex.library/regfree regex.library/regfree NAME regfree -- free a RE . SYNOPSI regfree(preg); a0 void regfree(regex_t *preg); FUNCTION Frees any dynamically-allocated storage associated with the compiled RE pointed to by preg . The remaining regex_t is no longer a valid compiled RE and the effect of supplying it to regexec or regerror is undefined. INPUT preg - a pointer to a reg expression compiled with recomp.