[antlr-interest] Implicit Typecasting with a tree grammar

Tilman Bender tbender at stud.hs-heilbronn.de
Thu Apr 9 04:35:49 PDT 2009


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
tbender at stud.hs-heilbronn.de



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