[Boost-users] Re: [regex] Is there any function to know where the input fails to match a regex?

From: jordi (jordil2_at_[hidden])
Date: 2005-02-14 06:48:48

John Maddock wrote:
>> With my undefined funtion I would obtain:
>>
>> - Input text:"123 hello abc"
>> - Latest rigth Regular expression: "(\d)+\s+(\w)+\s+" Matches: "123 
>> hello "
>> - First wrong regex: "(\d)+\s+(\w)+\s+(\d)+" does not match.
>>
>> -> So, "(\d)+" does not match "abc"
>>
>> I understand that usually this is not as easy as I write in my simple 
>> example because of the power of regular expressions but I think a 
>> function like that would improve a lot the error reporting 
>> capabilities. Is there any way to do what I need or I must to write my 
>> own check function?
> 
> 
> That would indeed be useful: actually what we really need is a regular 
> expression debugger, but both need a fully instrumented regex engine to 
> associate states in the machine with characters in the original 
> expression (so you know where the failure occurred).
> 
> I'm afraid there's no way to do what you want at present, it's always 
> been on my TO-DO list, but never seems to have surfaced !
> 
> John.
Does anyone know any application/utility that includes this feature (or 
a regular expression debugger)?  At least this utility would be easier 
to define (and check) a regular expression against a difficult input.

Thanks anyway,

Jordi