Can anyone help me find an efficient implementation.
If the cost of a subroutine call is cheaper than scanning the list (which I suspect is the case), then you can assemble all the target patterns into one, perform a single match, and then dispatch to the sub that gives you what you want to substitute:
#! /usr/local/bin/perl -w
use strict;
use Regexp::Assemble;
my $ra;
my %dispatch = (
'food' => sub { 'pizza' },
'water' => sub { 'beer' },
'like' => sub { 'enjoy' },
'(\d+)F' => sub { int(($ra->mvar(1) - 32 ) * 5/9 ) . 'C' },
);
$ra = Regexp::Assemble->new( track => 1 )->add( keys %dispatch );
while( <DATA> ) {
while( $ra->match($_) ) {
my $m = $ra->matched;
s/$m/&{$dispatch{$m}}/e;
}
print;
}
__DATA__
I'd like a glass of water with my food, it's 92F in here!
... produces...
I'd enjoy a glass of beer with my pizza, it's 33C in here!
Generating the dispatch table from a data file is left as an exercise to the reader (but a pretty fun one, I might say).
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