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/*
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 Copyright (c) 2005-2009 Terence Parr
 All rights reserved.

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 1. Redistributions of source code must retain the above copyright
     notice, this list of conditions and the following disclaimer.
 2. Redistributions in binary form must reproduce the above copyright
     notice, this list of conditions and the following disclaimer in the
     documentation and/or other materials provided with the distribution.
 3. The name of the author may not be used to endorse or promote products
     derived from this software without specific prior written permission.

 THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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package org.antlr.runtime.tree;

import org.antlr.runtime.RecognizerSharedState;
import org.antlr.runtime.RecognitionException;
import org.antlr.runtime.TokenStream;

public class TreeFilter extends TreeParser {
    public interface fptr {
        public void rule() throws RecognitionException;
    }

    protected TokenStream originalTokenStream;
    protected TreeAdaptor originalAdaptor;

    public TreeFilter(TreeNodeStream input) {
        this(input, new RecognizerSharedState());
    }
    public TreeFilter(TreeNodeStream input, RecognizerSharedState state) {
        super(input, state);
        originalAdaptor = input.getTreeAdaptor();
        originalTokenStream = input.getTokenStream();
    }

    public void applyOnce(Object t, fptr whichRule) {
        if ( t==null ) return;
        try {
            // share TreeParser object but not parsing-related state
            state = new RecognizerSharedState();
            input = new CommonTreeNodeStream(originalAdaptor, t);
            ((CommonTreeNodeStream)input).setTokenStream(originalTokenStream);
            setBacktrackingLevel(1);
            whichRule.rule();
            setBacktrackingLevel(0);
        }
        catch (RecognitionException e) { ; }
    }

    public void downup(Object t) {
        TreeVisitor v = new TreeVisitor(new CommonTreeAdaptor());
        TreeVisitorAction actions = new TreeVisitorAction() {
            public Object pre(Object t)  { applyOnce(t, topdown_fptr); return t; }
            public Object post(Object t) { applyOnce(t, bottomup_fptr); return t; }
        };
        v.visit(t, actions);
    }
        
    fptr topdown_fptr = new fptr() {
        public void rule() throws RecognitionException {
            topdown();
        }
    };

    fptr bottomup_fptr = new fptr() {
        public void rule() throws RecognitionException {
            bottomup();
        }
    };

    // methods the downup strategy uses to do the up and down rules.
    // to override, just define tree grammar rule topdown and turn on
    // filter=true.
    public void topdown() throws RecognitionException {;}
    public void bottomup() throws RecognitionException {;}
}

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