[antlr-interest] AST transforms - propagation of semanticinformation

[Sam Harwell]

Use a custom tree adaptor and write your rules like this:

foo
  : ^(IMPL ^(OR x+=form+) y=form)
    -> ^(AND[$IMPL] ^(AS_IMPL $x $y)+)
  ;

Then put the semantics to duplicate the information in the constructor
for your custom node type.

Sam

-----Original Message-----
From: antlr-interest-bounces at antlr.org
[mailto:antlr-interest-bounces at antlr.org] On Behalf Of Bill Andersen
Sent: Thursday, November 13, 2008 2:02 PM
To: antlr-interest at antlr.org
Subject: [antlr-interest] AST transforms - propagation of
semanticinformation

Folks,

Here's a fragment of a AST transformation grammar I'm working on

foo
	: ^(IMPL ^(OR x+=form+) y=form)
		-> ^(AND ^(AS_IMPL $x $y)+)
	;

I want to keep certain semantic information on tree nodes.  Figured  
out already how to do this with custom node classes.  What I want, in  
the example of the rule above, is for the semantic information on the  
root node (IMPL) to be automatically propagated to the output root  
node (AND).  Of course I can write actions in each such production to  
do this, but I have a whole lot of productions like this and writing  
all those actions is a maintenance problem.

Is there some way to do this pervasively, perhaps with a custom  
TreeAdaptor?  Thanks in advance.

	bill

Bill Andersen
Ontology Works, Inc. (www.ontologyworks.com)
3600 O'Donnell Street, Suite 600
Baltimore, MD 21224
Office: +1.410.675.1201
Cell: +1.443.858.6444
Fax: +1.410.675.1204





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