[il-antlr-interest: 23412] Re: [antlr-interest] Implicit Typecasting with a tree grammar

[Tilman Bender]

Hi, I love replying to myself ;-) I found some way of achieving the implicit uppercast, but not using a tree grammar. I wrote my grammar to distinguish between int and float expressions right from the start. Unfortunately I now run into trouble. I added boolean expressions to my grammar and cannot find a way to make boolean _expression_ like: bool a := 3<4 work, but prevent my grammar from accepting things like bool a:=4 which is obviously bad.  So I had a look at the Java grammars on antlr.org and found that, they do not impose type restrictions on the parser side. E.g. with Terrence's Java 1.5 grammar: private boolean b = 3; is totally valid. I know that trying to catch violations in typing via the parser-grammar was a bad idea. But I cannot come up with a good solution to do this in an extra stage via a TreeWalker. Any help would be greatly appreciated.

Arith.g
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Arith.testsuite
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Tilman Bender Student des Software Engineering Hochschule Heilbronn tben...@stud.hs-heilbronn.de Am 09.04.2009 um 13:35 schrieb Tilman Bender: Hi there, I am still playing with my interpreter for arithmetic expressions. Now I would like to work with mixed expressions containing integer and floating point numbers. When doing so I would like to have the integers automatically "uppercasted" when they occur in an _expression_ together with floats.  So what I currently do is, that I have a Java class providing methods for the respective arithmetic operations and invoke it from my interpreter:  ^(MINUS a=expr b=expr)  { $value = Arithmetic.subtract($a.value,$b.value);} In the add-method I check for the type of the parameters passed in and do the conversion  to BigDecimal magic. However I would like to make this "implicit uppercast" independant from the host language for my interpreter to minimize the amount of code I have to change, when switching the host language.  Has anyone already done such a thing via a TreeWalker? Tilman Bender Student des Software Engineering Hochschule Heilbronn tben...@stud.hs-heilbronn.de List: http://www.antlr.org/mailman/listinfo/antlr-interest Unsubscribe: http://www.antlr.org/mailman/options/antlr-interest/your-email-address

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