[antlr-interest] Rewrite Problem,

[Craig Main]

Hi Ter,

I am still battling with this.
I do not understand the rewrite rules.

Given the following simple term, in the standard expression/term/factor
arrangement.

expression	: l=term ((op=PLUS|op=MINUS) r=term)*

If I write the expression with the correct tree manipulation operators:

expression	: l=term ((op=PLUS^|op=MINUS^) r=term)*

Then I get a complete AST tree when I parse the expression 'a = 90+23-11'
I can match the tree correctly with:

expression:
  #(PLUS l=expression r=expression)
| #(MINUS l=expression r=expression)


When I try to do the new stuff (version 3.0)
I leave out the tree manipulation as that produces an error.
I use:

expression	: l=term ((op=PLUS|op=MINUS) r=term)*

and then add:
-> ^($op $expression $r)*

And the tree is just a nil node.

I also tried

-> ^($op $l $r)*

And get the same thing.

Am I interpreting the thing wrong?

I have included the grammar in case anyone wants to have a quick squiz.
In its current form, I loose the +23 in 'a = 90+23-11'
Regards
Craig
 

To: Antlr Interest
Subject: Re: [antlr-interest] Rewrite Problem,

Hi.  Try

^($operator $expression $rvalue)*

:)

which means make a new root with left child consisting of old  
expression and right child of new operand.
Ter
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