Beefy Boxes and Bandwidth Generously Provided by pair Networks
No such thing as a small change
 
PerlMonks  

Re: Crafting a regex

by ahunter (Monk)
on Oct 11, 2000 at 21:29 UTC ( #36262=note: print w/ replies, xml ) Need Help??


in reply to Crafting a regex

Perl is fairly good at compiling regexps, and provided you only use the constructs that can be simulated with a 'standard' regexp (which is to say, provided you can construct a deterministic finite automata from the expression), the running time should be O(n), where n is the length of the string being matched against.

This means you should avoid using anything that might cause perl to backtrack or lookahead - mostly that means the (?...) operators.

Anyhow, from your example, it looks like the closing quote is always the last one, so you could just take advantage of perl's greediness and use the following regexp, which should run at exactly the same speed as your original:

/^(\S+).*?\[(\S+).*?] (\S+) "(.+)" (\d+)/
Andrew.


Comment on Re: Crafting a regex
Download Code

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://36262]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others perusing the Monastery: (6)
As of 2014-09-21 02:48 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    How do you remember the number of days in each month?











    Results (166 votes), past polls