[antlr-interest] Attributes on AST nodes

Priya priya.uky at gmail.com
Tue Mar 21 08:28:07 PST 2006

Hi Everyone,
I am parsing a C-like syntax with C++ grammar specified in ANTLR.
This is a small snippet from my program .

int:3 a[10]; // a 3 bit integer declaration
int:4 b[10];
int:2 c[5];

The grammar description looks like

type COLON Integer Name LSQB Integer RSQB SEMI;

I modify the default AST structure and now the  AST for this
declaration looks like

a----------------b ----------------c
|                  |                  |
int---[           int---[           int---[
|      |            |     |            |     |
3     10         4    10         2     5

for the declaration part
 I make the AST nodes a ,b and c to be of type NAMENode , where i
override the Base
AST factory that I already have with the methods of NAMENode and i add
additional methods called get_width() and get_precision() that walk
down the tree to get the values using the getFirstChild() and
getNextSibling() methods . This width and precision information is
recorded in a symbol table ...

when I encounter an expression like the following in my source language ,

I want to know the precision of the variables 'a' and 'b'  and perform
a promotion operation in order to add the two variables.
I can go do a symbol table look up to find this out but ,
Is there a way to directly encode the precision and width information as
a.precision , b.precision  a.width b.width etc directly  in the node itself?

Hope i made my question clear ..
Thanks in advance for your help

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