RE(3ast)

NAME
recomp, reexec, ressub, refree, reerror - regular expression library

SYNOPSIS
    #include <re.h>
    Re_program_t* recomp(char* pattern, int flags);
    int reexec(Re_program_t* re, char* source);
    void ressub(Re_program_t* re, Sfio_t* sp, char* old, char* new, int flags);
    void reerror(char* message);
    void refree(Re_program_t* re);

DESCRIPTION
compiles a regular expression in pattern and returns a pointer to the compiled regular expression. The space is allocated by malloc(3) and may be released by Regular expressions are as in egrep(1) except that newlines are treated as ordinary characters and matches the end of a null-terminated string. flags may be which specifies ed(1) style special characters, and for the egrep(1) and respectively.

matches the null-terminated source string against the compiled regular expression re from a previous call to If it matches, returns a non-zero value. If flags is then the array re->match is filled with character pointers to the substrings of source that correspond to the parenthesized subexpressions of pattern: re->match[i].sp points to the beginning and re->match[i].ep points just beyond the end of substring i. (Subexpression i begins at the ith matched left parenthesis, counting from 1.) Pointers in re->match[0] pick out the substring that corresponds to the entire regular expression. Unused elements of re->match are filled with zeros. Matches involving and are extended as far as possible. A maximum of 9 subexpressions will be matched. The structure of elements of re->match is:
	typedef struct
	{
		char* sp;
		char* ep;
	} rematch;

places in the sfio(3) stream sp a substitution instance of old to new in source in the context of the last performed on re->match. Each instance of where n is a digit, is replaced by the string delimited by and Each instance of is replaced by the string delimited by re->match[0].sp and re->match[0].ep. If is set in flags then all occurrences of old are replaced by new. If is set in flags then old is converted to lower [upper] case.

called whenever an error is detected in or writes the string msg on the standard error file and exits. may be replaced to perform special error processing.

DIAGNOSTICS
returns 0 for an invalid expression or other failure. returns 1 if source is accepted, 0 otherwise.

SEE ALSO
ed(1), grep(1), expr(1)