Re: Expression simplifier.

> \ B. Rasmus Anthin
> / e8rasmus@etek.chalmers.se
> / www.etek.chalmers.se/~e8rasmus
> [I'd have a set of tree rewriting patterns, e.g. X+0 -> X -John]


Hmmm... But then I have to transform the tree into a binary tree in order
to accomplish this, right?
If I have: "8+3+y" this would then give me a AST like this:


                                                      expression
                                              / / | \ \
                                        / / | \ \
                                    term addop term addop term
                                      | | | | |
                                  factor '+' factor '+' factor
                                      | | |
                                  primary primary primary
                                      | | |
                                    id id id
                                      | | |
                                    '8' '3' 'y'


And the binary tree would then look like:


                +
            / \
          + y
      / \
    8 3


Elimination would then give


                +
            / \
          11 y


Is this correct? And if this is the case, then how would I implement this?
Will I have to transform the eliminated binary tree into an AST again and
then traverse it in order to receive an eliminated expression?


I have the dragon-book, "Writing Compilers and Interpreters" (R. Mak) ,
"Crafting a Compiler with C" (Fischer,LeBlanc) and "Compiler
Construction" (Niklaus Wirth). Can I find anything about it there? I have
looked for it there at a glance but couldn't find anything of use there.




Sincerely,


//Raz
[Yes, see the next few messages. -John]

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