Re: [boost] [regex] specify parenthesis

From: Paul Giaccone (paulg_at_[hidden])
Date: 2007-05-01 05:55:24

Lorenzo Bettini wrote:
> John Maddock wrote:
>   
>> Lorenzo Bettini wrote:
>>     
>>> Hi
>>>
>>> is there a way to specify open and closed parenthesis with a
>>> regular expression syntax?  For instance, if I'd want to specify a
>>> single regular expression that matches both (foo) and [foo] and {foo}?
>>>       
>> Probably not what you wanted, but:
>>
>> [(\[{]foo[)\]}]
>>
>>     
>
> but this would match also {foo] which would wrong...
>   

You could use Spirit, of course, using a function that recorded which 
type of bracket (pedantic point: "(", "), "[", "]", "{" and "}" are all 
brackets, but only "(" and ")" are parentheses) was found first and 
another function that tested whether the close bracket matched the open 
bracket; this way, you could even check for correctly nested brackets if 
you wanted to. The downsides with using Spirit are:

* if you don't already know it, you'll have to learn a fair bit of 
Spirit in order to do this;
* it will add quite a big chunk of code to your source for what is, 
after all, a simple parsing operation;
* it will increase the size of your executable considerably;
* it will (possibly) be slower than regex.

I'd suggest seeing if anyone else comes up with a solution using regex, 
and writing your own simple parser by hand (not using Spirit) if not.