Beefy Boxes and Bandwidth Generously Provided by pair Networks
Your skill will accomplish
what the force of many cannot
 
PerlMonks  

Re: hashes in regexes

by bjelli (Pilgrim)
on Mar 29, 2001 at 05:26 UTC ( #68021=note: print w/ replies, xml ) Need Help??


in reply to hashes in regexes

As a lowly acolyte I have great respect for <kbd>map</kbd> and a fondness of good old <kbd>foreach</kbd>. So I naturally thought: isn't a loop with simple pattens faster than a pattern with <kbd>|</kbd> in it?

Here's my benchmarking code:

use Benchmark; timethese(500, { 'or pattern' => \&orpattern, 'many patterns' => \&manypatterns }); sub init { %sub_hash = (John => Mike, Jack => Mark, Joe => Moe); $string = "Dear John!.\nI've run off with Jack and Joe.\nSue\n\n" x 1000; } sub orpattern { init; my $keys = join '|', map "\Q$_\E", keys %sub_hash; my $keys_REx = qr/$keys/; $string =~ s/($keys_REx)/$sub_hash{$1}/g; return $string; } sub manypatterns { init; my %patterns = map { qr/$_/ => $sub_hash{$_} } keys %sub_hash; foreach $pat (keys %patterns) { my $replace = $patterns{$pat}; $string =~ s/$pat/$replace/g; } return $string; }

And the results:

Benchmark: timing 500 iterations of many patterns, or pattern...
many patterns:  2 wallclock secs ( 1.61 usr +  0.00 sys =  1.61 CPU)
or pattern: 12 wallclock secs (11.94 usr +  0.01 sys = 11.95 CPU)

Of course there's a difference in functionality between the two, just think of:

%substitute_hash = ( Jack => Chris, Chris => Jaquline );
--
Brigitte    'I never met a chocolate I didnt like'    Jellinek
http://www.horus.com/~bjelli/         http://perlwelt.horus.at


Comment on Re: hashes in regexes
Select or Download Code

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://68021]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others studying the Monastery: (14)
As of 2015-07-29 18:38 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    The top three priorities of my open tasks are (in descending order of likelihood to be worked on) ...









    Results (267 votes), past polls