Re: [boost] [regex] specify parenthesis

From: Lorenzo Bettini (bettini_at_[hidden])
Date: 2007-05-01 11:31:13

John Maddock wrote:
> Lorenzo Bettini wrote:
>> do you happen to know whether there are any specifications for regular
>> expressions for matching parenthesis (I mean in any regexp frameworks
>> or libraries)?
> 
> Not really no, but I have another idea, assuming the x-modifier is on:
> 
> (?x)
> (?:
>   (\()
>   |(\[)
>   |(\{)
> )
> foo
> (?:
>   (?(1)\)
>   |(?:(?(2)\]
>   |(?:\}
> ))))
> 
> The idea is to use conditional expressions to check which opening backet 
> matched and then react accordingly.  You'll need to check I've got the ('s 
> and )'s matching up 'cos I lost count while typing in :-(
> 

that's actually what I myself thought I might turn to if there was no
way of matching parenthesis (or brackets) with regular expression syntax
I was asking for :-)

I'll see whether this technique makes my regular expressions harder to
read than a simple copy and paste solution.

I thought there might be a syntax for it because I read in the regex
documentation, in the section "Character classes that are supported by
Unicode Regular Expressions" these syntaxes

Ps  Open Punctuation
Pe  Close Punctuation

and I thought they might be related (by the way, I actually did not
understand what they're for, since there's no example).

Lorenzo

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Lorenzo Bettini, PhD in Computer Science, DSI, Univ. di Firenze
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