I want to apply a set of regex on each line of this file

At the risk of tiring readers with yet another plug for my module, I'll point out that it offers a "tracked pattern" mode, whereby you can assemble your array of regexps into a single pattern, which gives you the efficiency of performing a single match, and the convenience of being able to determine which, of the original expressions, was the one that matched. The code would go something like: 

use strict;
use Regexp::Assemble;

my $re = Regexp::Assemble->new( track => 1 );

open IN, shift || 'patterns' or die "open pattern file: $!\n";
while( <IN> ) {
    chomp;
    $re->add($_);
}
close IN;

# read from, e.g., STDIN
while( <> ) {
    chomp;
    if( defined( my $match = $re->match($_)) ) {
        print "  $_ matched by $match\n";
    }
}

[download]

What is not obvious, is that behind the scenes, the $re->match() is performing a single match. It is not looping over the entire list of patterns. It has to be this way (rather than using the more intuitive if( /$re/ ) {...}) because of current broken behaviour in the regular expression engine (see bug #32840 for details).

Printing out the which particular pattern caused the match is not particularly helpful. What you really want to do is use the result as a hash key, either to look up a "human-readable" result string or a callback function, whatever suits your needs. If your patterns have captures (e.g. /x=(\d+)/), they are available for use.

- another intruder with the mooring in the heart of the Perl

In reply to Re: Regex and question of design by grinder
in thread Regex and question of design by amaguk

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