Re: [boost] Re: [ANN] Spirit C++ parser framework.

From: John Max Skaller (skaller_at_[hidden])
Date: 2001-05-25 13:16:19

joel de guzman wrote:

> OK. Sorry if that wasn't clear. For the record: Spirit is an
> exhaustive back-tracking recursive descent parser generator.

        That still isn't clear to me :-)

        Is Spirit a genuine _top down_ backtracking parser, 
or merely recursive descent? Can you parse

        (a|b)*abb

This cannot be parsed by recursive descent, because RD only
backtracks to the last node containing another choice
and which _also_ contains the failure. Real backtracking
backtracks to the last node examined containing another
choice, it need not contain the subgoal, and the subgoal
might include success as well as failure (depending
on whether you want one parse, or all of them).

-- 
John (Max) Skaller, mailto:skaller_at_[hidden]
10/1 Toxteth Rd Glebe NSW 2037 Australia voice: 61-2-9660-0850
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