RE: [Boost-users] Regex lookahead/lookbehind

From: James Gunn (james.gunn_at_[hidden])
Date: 2004-06-15 07:35:25

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Hi John,

> -----Original Message-----
> From: John Maddock [mailto:john_at_[hidden]] 
> Sent: 15 June 2004 12:40
> To: boost-users_at_[hidden]
> Subject: Re: [Boost-users] Regex lookahead/lookbehind
> 
> 
> > Hi all,
> >
> > Is it possible to do lookahead and/or lookbehind within 
> boost::regex?
> 
> Lookahead is supported at present, lookbehind will be in the 
> next revision (currently in cvs in the branch called regex5).
> 
> John.

Thanks for the quick response. In the end I managed to solve my current
problem without
needing lookahead or lookbehind. 

I used your (earlier) advice of checking for word boundaries at the
beginning and end of my regular 
expression and this has helped loads! The latest version of my postcode
validation expression is shown below:

(\bGIR\s0AA\b)|
(\b[^QVX\W0-9][^IJZ\W\s]([0-9]{1,2}?|[ABCDEFGHJKSTUW0-9]?|[0-9][ABEHMNPRVWXY
]?)
\s+\d[^CIKMOV]{2}\b)

I'm certain that the expression could be made simpler and that it could also
be made more efficient but I'm not sure where.

Cheers,

James

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