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

Re^4: Regex Greed

by Athanasius (Prior)
on Aug 08, 2012 at 02:42 UTC ( #986115=note: print w/ replies, xml ) Need Help??


in reply to Re^3: Regex Greed
in thread Regex Greed

A search on “overlapping matches’ in perldoc doesn’t turn up anything relevant. However, I did find the following in the Camel Book (4th Edition, pages 247–8, underlining added):

Lookahead assertions can be used to implement overlapping matches. For example,
"0123456789" =~ /(\d{3})/g
returns only three strings: 012, 345, and 678. By wrapping the capture group with a lookahead assertion:
"0123456789" =~ /(?=(\d{3}))/g
you now retrieve all of 012, 123, 234, 345, 456, 567, 678, and 789. This works because this tricky assertion does a stealthy sneakahead to run up and grab what’s there and stuff its capture group with it, but being a lookahead, it reneges and doesn’t technically consume any of it. When the engine sees that it should try again because of the /g, it steps one character past where last it tried.

HTH,

Athanasius <°(((><contra mundum


Comment on Re^4: Regex Greed
Select or Download Code

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://986115]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others having an uproarious good time at the Monastery: (4)
As of 2014-07-12 11:43 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    When choosing user names for websites, I prefer to use:








    Results (239 votes), past polls