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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 >