Re: [Boost-bugs] [Boost C++ Libraries] #3899: Regex: Bug in handling of "\Z"

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #3899: Regex: Bug in handling of "\Z"
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2010-02-05 12:50:30

#3899: Regex: Bug in handling of "\Z"
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 Reporter:  Keith MacDonald <keith@…>            |       Owner:  johnmaddock
     Type:  Bugs                                 |      Status:  new        
Milestone:  Boost 1.43.0                         |   Component:  None       
  Version:  Boost 1.42.0                         |    Severity:  Problem    
 Keywords:                                       |  
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Comment(by johnmaddock):

 There are two separate issues here:

 1) Boost.Regex has always treated all line-termination characters as
 equivalent, so for example $ will match before any line-termination
 sequence: \n \r\n \r plus a few other unicode-specific sequences.  This is
 different to Perl's behaviour, but then Perl has complete control over
 file IO and text file formats and line endings where as Boost.Regex does
 not - and is intended to work with all text file formats wherever they're
 from and however they're read in.  This seems to have worked well in
 practice up until now, and I don't really want to change it.

 2) The behaviour of \Z in Perl seems to be quite "quirky" ;-)  In fact
 it's quite hard to write a regular expression that matches it's behaviour
 exactly!  From messing around it seems to be:

 $(?=\n\z)|\z

 where as Boost is doing:

 $(?=\v+\z)|\z

 This one I will look into changing, even though I would argue that the
 current behaviour is often more useful :-)

 John.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/3899#comment:3>
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