Simply using a tree grammar won't alter the input tree. If you want
customizable actions, use something like this:
tokenSpec
: TOKEN_REF {TrackToken($TOKEN_REF);}
;
Then in your helper file (which you can create since the tree grammar
class is declared partial in code), create a virtual stub method that
"handles" things:
protected virtual void TrackToken(CommonTree tokenRef)
{
}
Then you can derive classes from the tree parser and override methods as
needed to provide the required functionality. In the C# port of the
ANTLR tool, this exact method is used to implement the functionality for
the AssignTokenTypesWalker tree parser (the lines above are actually
taken from it).
Sam
From: [email protected]
[mailto:[email protected]] On Behalf Of Rob Dougan
Sent: Thursday, July 30, 2009 1:48 PM
To: ANTLR Interest
Subject: [antlr-interest] Approach to Multiple Passes using Tree
Grammars without Filters (C#)?
Antlr 3.1.3 does not have tree filters.
Pass 1: lex/parse produces AST,
I would like to do multi-pass processing on AST produced in first pass.
Pass 2: Tree grammar A (AST): variable defs, build symbol table etc
Pass 3: Tree grammar B (AST): static type checking etc.
Pass 4: Tree grammar C (AST): execute
If i do not have tree filters, do I have copy the tree grammar three
times and modify the actions to accomplish the task?
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