term% cat index.txt REGEXP(2) System Calls Manual REGEXP(2)
NAME
regcomp, regcomplit, regcompnl, regexec, regsub, rregexec, rregsub,
regerror - regular expression
SYNOPSIS
#include <u.h>
#include <libc.h>
#include <regexp.h>
Reprog *regcomp(char *exp)
Reprog *regcomplit(char *exp)
Reprog *regcompnl(char *exp)
int regexec(Reprog *prog, char *string, Resub *match, int msize)
void regsub(char *source, char *dest, int dlen, Resub *match, int msize)
int rregexec(Reprog *prog, Rune *string, Resub *match, int msize)
void rregsub(Rune *source, Rune *dest, int dlen, Resub *match, int msize)
void regerror(char *msg)
DESCRIPTION
Regcomp compiles a regular expression and returns a pointer to the gen‐
erated description. The space is allocated by malloc(2) and may be re‐
leased by free. Regular expressions are exactly as in regexp(6).
Regcomplit is like regcomp except that all characters are treated lit‐
erally. Regcompnl is like regcomp except that the . metacharacter
matches all characters, including newlines.
Regexec matches a null-terminated string against the compiled regular
expression in prog. If it matches, regexec returns 1 and fills in the
array match with character pointers to the substrings of string that
correspond to the parenthesized subexpressions of exp: match[i].sp
points to the beginning and match[i].ep points just beyond the end of
the ith substring. (Subexpression i begins at the ith left parenthe‐
sis, counting from 1.) Pointers in match[0] pick out the substring
that corresponds to the whole regular expression. Unused elements of
match are filled with zeros. Matches involving and are extended as far
as possible. The number of array elements in match is given by msize.
The structure of elements of match is:
typedef struct {
union {
char *sp;
Rune *rsp;
};
union {
char *ep;
Rune *rep;
};
} Resub;
If match[0].sp is nonzero on entry, regexec starts matching at that
point within string. If match[0].ep is nonzero on entry, the last
character matched is the one preceding that point.
Regsub places in dest a substitution instance of source in the context
of the last regexec performed using match. Each instance of \n, where
n is a digit, is replaced by the string delimited by match[n].sp and
match[n].ep. Each instance of is replaced by the string delimited by
match[0].sp and match[0].ep. The substitution will always be null ter‐
minated and trimmed to fit into dlen bytes.
Regerror, called whenever an error is detected in regcomp, writes the
string msg on the standard error file and exits. Regerror can be re‐
placed to perform special error processing. If the user supplied
regerror returns rather than exits, regcomp will return 0.
Rregexec and rregsub are variants of regexec and regsub that use
strings of Runes instead of strings of chars. With these routines, the
rsp and rep fields of the match array elements should be used.
SOURCE
/sys/src/libregexp
SEE ALSO
grep(1)
DIAGNOSTICS
Regcomp returns 0 for an illegal expression or other failure. Regexec
returns 0 if string is not matched.
BUGS
There is no way to specify or match a NUL character; NULs terminate
patterns and strings.
REGEXP(2)