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GenLex stream parsers too eager?
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Date: -- (:)
From: mattwb@v...
Subject: Re: GenLex stream parsers too eager?

>
>From: "David McClain" <dmcclain@azstarnet.com>
>
>It appears that the Genlex derived parsers always eagerly tokenize =
>negaitve integer and float constants. This causes incorrect behavior in =
>closely spaced code (no-spaces):
>
>    a-2*c  --> parses as  "a", "-2" ,"*", "c"  instead of =
>"a","-","2","*","c"
>
>So instead of getting one expression tree, I get two, with the first =
>containing only "a".
>Also, if the operator were exponentiation instead of multiplication, the =
>second tree would incorrectly compute a (possibly) complex valued =
>expression instead of a simple negative of a real expression.
>
>I have tried various workarounds, but they really obfuscate the original =
>recursive descent structure of parsers.
>
>Any suggestions? (Perhaps I should be using OCAMLLEX and OCAMLYACC =
>instead?)
>

I'd certainly suggest not using Genlex except for only the most trivial
things.  Ocamllex and ocamlyacc are not difficult and they're much more
powerful.

>David McClain
>Sr. Scientist
>Raytheon Missile Systems Co.
>Tucson, AZ
>http://www.azstarnet.com/~dmcclain/homepage.htm
>