|[11 earlier articles]|
|Re: Bottom-up versus Top-down firstname.lastname@example.org (1997-12-05)|
|Re: Bottom-up versus Top-down email@example.com (1997-12-07)|
|Re: Bottom-up versus Top-down firstname.lastname@example.org (Henry Spencer) (1997-12-07)|
|Re: Bottom-up versus Top-down email@example.com (1997-12-07)|
|Re: Bottom-up versus Top-down firstname.lastname@example.org (Jeff Jenness) (1997-12-10)|
|Re: Bottom-up versus Top-down email@example.com (Scott Stanchfield) (1997-12-10)|
|Re: Bottom-up versus Top-down firstname.lastname@example.org (1997-12-12)|
|From:||email@example.com (Torben AEgidius Mogensen)|
|Date:||12 Dec 1997 14:44:09 -0500|
|Organization:||Department of Computer Science, U of Copenhagen|
|References:||97-11-123 97-11-155 97-11-178 97-12-024 97-12-055 97-12-073|
"Scott Stanchfield" <firstname.lastname@example.org> writes:
>For some info on converting grammar from LALR to LL, see
As I see it, a major advantage of LR over LL is the ability to use
operator precedence rules instead of using a non-ambiguous grammar.
Though precedence-annotated grammars can be rewritten to a
non-ambiguous grammar and left-recursion can be eliminated from this,
the size of the resulting grammar can be very large if you have both
prefix, infix and postfix operators. In addition to increasing the
size of the grammar, the disambiguating rewrites also slow down the
parsing by requiring more derivation steps.
That said, LR tables are often larger than LL tables, and the same is
true for explicitly written recursive descent/ascent. This doesn't
seem to be a problem until you get extremely large grammars, though.
Torben Mogensen (email@example.com)
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