[antlr-interest] basic doubt to assign value to AST nodes!!

mark twain himmy070 at gmail.com
Thu Aug 21 07:43:05 PDT 2008


Hi Every1...

I am newbie here and just few days back started working on this cool ANTLR .
Have a very basic question on assigning the values to AST nodes. So far, I
am able to generate the AST supporting simple arithmetic operations  and
also able to evaluate the tree.  Just an example, if my

input expression is: a = 1+ 2 , I can generate following AST and also able
to evaluate it and get output : 3
 AST :       =
             /     \
           a        +
                   /    \
                  1      2

This way if my expression changes to  a = 3+4(say) I generate AST again and
evaluate the output from AST
But now say instead of 1 and 2, I make it generic and use b and c to
generate the AST. Now, is there is anyway I can assign the values to b and c
of AST without a need to create AST again and again for different values of
b and c. I want flow of execution code to be:
===========================================
func1 (a = b + c)           // generate the AST from variables *just once*

func2 (2, 3)                  //expected output value of a = 5
func2(4,5)                    //expected output value of a = 9
...
...
==========================================
So, this way I wanna create AST only if my arithmetic formula changes......

cheers:)
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