Beefy Boxes and Bandwidth Generously Provided by pair Networks
Think about Loose Coupling

Re: Slow Regex - How to Optimize

by dave_the_m (Prior)
on Aug 30, 2005 at 21:50 UTC ( #487961=note: print w/replies, xml ) Need Help??

in reply to Slow Regex - How to Optimize

You code causes the regex to be recompiled each time round the inner loop. A slight rearrangement should improve things:
foreach my $sub ( keys %SUBS ) { my $re = qr/[^a-zA-Z]$sub[^a-zA-Z]*\(/; foreach my $line ( @sub_code ) { if ( $line =~ $re ) { push( @subs, $key ) } } }


Replies are listed 'Best First'.
Re^2: Slow Regex - How to Optimize
by ikegami (Pope) on Aug 30, 2005 at 22:05 UTC

    That's not true. m/.../ only recompiles if the contents of any interpolated variable has changed. Demo:

    use re 'debug'; foreach (qw( abc abc def )) { print("==============================\n"); print("$_\n"); print("\n"); /$_/; }

    Update: Oops, I didn't notice you reversed the loops in addition to moving the regexp.

Re^2: Slow Regex - How to Optimize
by Anonymous Monk on Mar 11, 2016 at 14:14 UTC
    great post.. thanks a lot :) it really solved an issue here. reduced the runtime of a usecase from 30 minutes to ~10 seconds. hats off! :)

Log In?

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://487961]
and all is quiet...

How do I use this? | Other CB clients
Other Users?
Others having an uproarious good time at the Monastery: (3)
As of 2017-12-16 14:24 GMT
Find Nodes?
    Voting Booth?
    What programming language do you hate the most?

    Results (453 votes). Check out past polls.