Re: C++ parsing : what's new ?

On 3 Jan 2002 16:37:58 -0500, SLK Parsing posted:
>> As I recall the motivation is performance. The people doing the
>> rewrite expect the recursive descent parser to be way faster than
>> the table-driven one they have now.
>
> Just to clarify, the main comparison here is between top-down and
> bottom-up parsing. Top-down is somewhat faster because more of the
> runtime work is encoded in the grammar. The trade off is its weaker
> recognition ability.
>
> From Fischer & LeBlanc "Crafting a Compiler with C", page 120:
>
> "Since the LL(1) driver uses a stack rather than recursive procedure
> calls to store symbols yet to be matched, the resulting parser can be
> expected to be smaller and faster than a corresponding recursive
> descent parser."


This is only relevant if the language you're writing the parser in
makes function calls as expensive as C does, though, right? Would it
be fair to assume that languages that optimise function calls heavily
(say, lisps and functional languages) are likely to have equivalent
performance for an LL(1) driver and a recursive descent parser?


mrak

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