Re: [Boost-bugs] [Boost C++ Libraries] #4309: Negative lookbehind assertion error

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #4309: Negative lookbehind assertion error
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2010-06-08 10:20:23

#4309: Negative lookbehind assertion error
 Reporter: anonymous | Owner: johnmaddock
     Type: Bugs | Status: new
Milestone: Boost 1.43.0 | Component: regex
  Version: Boost 1.43.0 | Severity: Problem
 Keywords: |

Comment(by anonymous):

 I wouldn't be too sure.

 A zero-width negative look-behind assertion. For example /(?<!bar)foo/
 matches any occurrence of "foo" that does not follow "bar". '''Works only
 for fixed-width look-behind'''.

 Both foo and bar are fixed-width, so ORing them should also be fixed
 width. There is no quantifier used in the sample.

 For comparison, in .NET, System.Text.RegularExpressions.Regex does it
 'right'. The .NET regular expression engine is designed to be mostly
 compatible with Perl 5 regular expressions. Hmmm?

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