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

From: Joel de Guzman (djowel_at_[hidden])
Date: 2002-10-12 00:28:47

----- Original Message ----- 
From: "Carl Daniel" <cpdaniel_at_[hidden]>

> More nits:
> 
> Exception classes thrown by Spirit (parser_error<>, illegal_backtracking)
> don't derive from std::exception - shouldn't they?

I'm not sure. Should it? What will be the benefits in doing so?
The truth is, I'm not quite happy with the standard C++ exceptions. 
For one, it's hard coded the what() to be a string.

Perhaps the language lawyers will correct me if I'm lost. :-)

> parser_error<> derives from parser_error_base, but illegal_backtracking
> (multi_pass.hpp) doesn't - shouldn't it?

Multi-pass is designed to be independent from Spirit. Doing
so will make it dependent.

> fixed_size_queue (usable with multi_pass_iterator) silently fails if too
> much source text is pushed.  Wouldn't throwing an exception be more
> appropriate?

The fixed sized queue is designed to be used in cases where the lookahead 
is known. There are lots of grammars that require only very limited lookahead 
for example; many times, only 1. In such cases, a fixed lookahead is 
guaranteed not to be overrun. fixed_size_queue is optional however. 
If the user is unsure, she can always use the std::queue.

--Joel