Re: [boost] Re: Formal Review: The Spirit Parser Framework.

From: Joel de Guzman (djowel_at_[hidden])
Date: 2002-10-15 19:37:53

----- Original Message ----- 
From: "Beman Dawes" <bdawes_at_[hidden]>

> At 09:45 PM 10/14/2002, Joel de Guzman wrote:
> 
>  >>    * Can easily parse local contradictions (always AB,
>  >>      except in certain expressions its BA).
>  >
>  >If I understand correctly, you mean special cases?
>  >Correct me if I'm wrong.
>  >
>  >The framework is malleable to special cases. There are exciting
>  >possibilities with dynamic parsing. Here's an example:
>  >
>  >    bool flag;
>  >    r =
>  >        if_p(flag)
>  >        [
>  >            parse_it_this_way
>  >        ]
>  >        .else_
>  >        [
>  >            parse_it_that_way
>  >        ]
>  >
>  >.. if(c)[p1].else_[p2]
>  >    parse p1 if c evaluates to true, else parse p2.
> 
> Yes, that is exactly what I meant. If what is being parsed is something 
> like a programming language, the designers usually try to avoid special 
> cases.  But if the input to be parsed comes from material extracted from 
> newspapers, for example, is is often shot through with special cases.  Glad 
> to hear Spirit can deal with special cases easily.

Even klunky programming languages such as C++ (hehe :) are full
of *context sensitive* special cases. The ability of Spirit to do 
dynamic parsing (parsers that change behavior at run time)
makes it able to parse context sensitive languages.

--Joel