REGEX(2)REGEX(2)NAMEregex - regular expression recognizer module
SYNOPSIS
include "regex.m";
regex := load Regex Regex->PATH;
compile: fn(e: string, flag: int): (Re, string);
execute: fn(x: Re; s: string): array of (int,int);
executese: fn(x: Re, s: string, se: (int, int), bol: int, eol: int):
array of (int, int);
DESCRIPTION
Regular expressions are defined by regexp(6). Compile returns (as the
first element of the result tuple) a compiled form of the regular
expression given in string e. If e is not a valid regular expression,
compile returns the tuple (nil, diag) where diag is a diagnostic
string. The effect of flag is described below.
Execute matches the compiled regular expression x against string s. It
returns nil on no match, otherwise it returns an array. The element
with index 0 gives the character positions of the first character of
some longest leftmost match and the first character beyond the match.
If the compilation flag was 0, there are no more elements. If flag was
1, there is one element for each pair of parentheses in the regular
expression, counting left parentheses left to right starting at 1. The
nth element gives the position of the last match to the nth parenthe‐
sized subexpression, or (-1,-1) if the subexpression does not partici‐
pate in the overall match.
Executese is similar to execute but allows the start and end points in
the string to be specified, as tuple se: (start , end), where start is
the index in s of the initial character to be matched, and end is the
index in s of the first character beyond the substring to be matched
(and can be the length of s). If bol is non-zero, the initial charac‐
ter is at the beginning of a line, allowing an initial match by the
regular expression operator `^'; if eol is non-zero, the last character
is at the end of a line, allowing a match by the operator `$'.
EXAMPLES
(re, nil) := regex->compile("(thick )*(chocolate |raspberry )?"+
"(topp|fill)ing", 0);
(re, nil) := regex->compile("[ABCb-z]+", 0);
a := regex->execute(re, s:="aAbBcCdD");
(beg, end) := a[0];
s[beg:end] == "AbBcCd";
(re, nil) := regex->compile("a*b*", 0);
a := regex->execute(re, "bbaabb");
(beg, end) := a[0];
(beg, end) == (0,2);
SOURCE
/appl/lib/regex.b
SEE ALSOregexp(6)REGEX(2)
