There are two ways to address this problem, using lazy quantifiers, or using a restrictive class. The lazy quantifier uses .*?, the restrictive class uses [^]]*. One would expect the latter to be faster, and in general it is, but in this case, with fixed delimiters, Perls optimization makes it faster: 
#!/usr/bin/perl

use strict;
use warnings;

use Benchmark;

our $loop_line = "static replace [something] and [another] thing";

our %replace = (something => "SOMETHING",
                another   => "ANOTHER");

my ($a, $b, $c);

timethese -1 => {
    lazy         =>  '$a = $loop_line; $a =~ s/\[(.*?)\]/$replace{$1}/
+g',
    restrictive  =>  '$b = $loop_line; $b =~ s/\[([^]]*)\]/$replace{$1
+}/g', 
    copy         =>  '$c = $loop_line;',
};

__END__
Benchmark: running copy, lazy, restrictive for at least 1 CPU seconds.
+..
       copy:  2 wallclock secs @ 3994936.79/s (n=4234633)
       lazy:  1 wallclock secs @  121663.37/s (n= 122880)
restrictive:  1 wallclock secs @  117028.57/s (n= 122880)

[download]
(Results slightly formatted for layout purposes). The copy clause shows that the impact of copying the string is small compared to the substitution.

Abigail

In reply to Re: Replacing multiple matches by Abigail-II
in thread Replacing multiple matches by alongwor

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