Folks
So I got my problem fixed with *making* custom AST nodes. I can make them and
pass the right parameters to them. Thanks to Jay for that.
Now, I'm trying to *use* them.
My AST consists of a mixture of ASNode (subclass of CommonTree) and CommonTree
nodes. Here's a production in a tree grammar I'm working on with template
output:
options {
ASTLabelType = CommonTree;
tokenVocab = AS;
output = template;
}
<snip>
rule
: ^(rNode=AS_RULE rName=ID alts+=alternative+)
{ System.out.println($rNode); }
-> pRule( rName={$rName.text}, rType={????} )
;
Question is what to put in place of ???? to get an attribute value out of
AS_RULE
Now, AS_RULE in input to this grammar is of type ASNode. Relevant portions
below:
public class ASNode extends CommonTree {
public ASType rType = null;
public ASNode() { }
public ASNode(int ttype, ASType rType) {
token = new CommonToken(ttype,"");
this.rType = rType;
}
public ASNode(int ttype) {
token = new CommonToken(ttype,"");
}
public ASType getRType() {
return rType;
}
}
If I put anything like $rNode.X, where X is a field or method access to an
ASNode instance, I get a Java compile error. ANTLR thinks $rNode is of type
CommonTree. So I figure I need to tell ANTLR what type to expect, so when I try
rule
: ^(rNode=AS_RULE<ASNode> rName=ID alts+=alternative+)
{ System.out.println($rNode); }
-> pRule( rName={$rName.text}, rType={$rNode.getRType()} )
;
I get the same compile error. Maybe I can change the options of all my
grammars to
ASTLabelType = ASNode;
but that defeats the whole purpose of having hetergeneous nodes, not to mention
I'm not sure what other side-effects this will cause.
So, what's the best way to get information out of these hetergeneous node
objects?
.bill
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