[antlr-interest] Custom data in ANTLR3_BASE_TREE in C runtime

[Jim Idle]

Dear Elvis,

I think that I have changed this so it is NULLed in the current development version, but you should be able to do this:

1) Set it to NULL yourself at an appropriate place. 
2) In the ANTLR source code, you will find:

#ifndef ANTLR3_MALLOC
/// Default definition of ANTLR3_MALLOC. You can override this before including
/// antlr3.h if you wish to use your own implementation.
///
#define	ANTLR3_MALLOC(request)          malloc  ((size_t)(request))
#endif

Change that to

#ifndef ANTLR3_MALLOC
/// Default definition of ANTLR3_MALLOC. You can override this before including
/// antlr3.h if you wish to use your own implementation.
///
#define	ANTLR3_MALLOC(request)          calloc  (1, (size_t)(request))
#endif


And rebuild the runtime and you will sacrifice a little performance for nulled space.

3) Find the code that creates new nodes from a tree factory (the function newPooltree in antlr3commontree.c) and before the return statement, add:

tree->baseTree.u = NULL;

This is essentially the fix in the current development branch.

Jim

> -----Original Message-----
> From: antlr-interest-bounces at antlr.org [mailto:antlr-interest-
> bounces at antlr.org] On Behalf Of Elvis Presley
> Sent: Thursday, May 06, 2010 10:12 AM
> To: antlr-interest at antlr.org
> Subject: [antlr-interest] Custom data in ANTLR3_BASE_TREE in C runtime
> 
> I'm using the ANTLR3 C runtime and I'd like to be able to add custom
> data to
> my AST.  I see there is a "u" field in the ANTLR3_BASE_TREE, which I
> would
> like to use to point to my own struct that contains the data I need for
> that
> node in the tree.  My problem is that it doesn't look like "u" is ever
> initialized to NULL so I don't have a way to determine if I need to
> allocate
> new memory for my struct or not.
> 
> I can't quite figure out by looking at the code if there is a way to
> override the behavior in ANTLR3_BASE_TREE or in the adaptor so that I
> can
> always guarantee that "u" is always NULL or points to one of my custom
> structs.   Any help here would be appreciated.  Thanks
> 
> --Bryce
> 
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