/Users/parrt/antlr/code/antlr/main/runtime/Java/src/main/java/org/antlr/runtime/tree/CommonTreeNodeStream.java

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/*
 [The "BSD license"]
 Copyright (c) 2005-2009 Terence Parr
 All rights reserved.

 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions
 are met:
 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.
 IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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package org.antlr.runtime.tree;

import org.antlr.runtime.Token;
import org.antlr.runtime.TokenStream;
import org.antlr.runtime.misc.LookaheadStream;
import org.antlr.runtime.misc.IntArray;

import java.util.*;

public class CommonTreeNodeStream extends LookaheadStream<Object> implements TreeNodeStream {
        public static final int DEFAULT_INITIAL_BUFFER_SIZE = 100;
        public static final int INITIAL_CALL_STACK_SIZE = 10;

        protected Object root;

        protected TokenStream tokens;

        TreeAdaptor adaptor;

    protected TreeIterator it;

    protected IntArray calls;    

    protected boolean hasNilRoot = false;

    protected int level = 0;

        public CommonTreeNodeStream(Object tree) {
                this(new CommonTreeAdaptor(), tree);
        }

        public CommonTreeNodeStream(TreeAdaptor adaptor, Object tree) {
                this.root = tree;
                this.adaptor = adaptor;
        it = new TreeIterator(adaptor,root);
        }

    public void reset() {
        super.reset();
        it.reset();
        hasNilRoot = false;
        level = 0;
        if ( calls != null ) calls.clear();
    }
    
    public Object nextElement() {
        Object t = it.next();
        //System.out.println("pulled "+adaptor.getType(t));
        if ( t == it.up ) {
            level--;
            if ( level==0 && hasNilRoot ) return it.next(); // don't give last UP; get EOF
        }
        else if ( t == it.down ) level++;
        if ( level==0 && adaptor.isNil(t) ) { // if nil root, scarf nil, DOWN
            hasNilRoot = true;
            t = it.next(); // t is now DOWN, so get first real node next
            level++;
            t = it.next();
        }
        return t;
    }

    public boolean isEOF(Object o) { return adaptor.getType(o) == Token.EOF; }

    public void setUniqueNavigationNodes(boolean uniqueNavigationNodes) { }

        public Object getTreeSource() { return root; }

        public String getSourceName() { return getTokenStream().getSourceName(); }

        public TokenStream getTokenStream() { return tokens; }

        public void setTokenStream(TokenStream tokens) { this.tokens = tokens; }

        public TreeAdaptor getTreeAdaptor() { return adaptor; }

        public void setTreeAdaptor(TreeAdaptor adaptor) { this.adaptor = adaptor; }

    public Object get(int i) {
        throw new UnsupportedOperationException("Absolute node indexes are meaningless in an unbuffered stream");
    }

    public int LA(int i) { return adaptor.getType(LT(i)); }

    public void push(int index) {
        if ( calls==null ) {
            calls = new IntArray();
        }
        calls.push(p); // save current index
        seek(index);
    }

    public int pop() {
        int ret = calls.pop();
        seek(ret);
        return ret;
    }    

        // TREE REWRITE INTERFACE

        public void replaceChildren(Object parent, int startChildIndex, int stopChildIndex, Object t) {
                if ( parent!=null ) {
                        adaptor.replaceChildren(parent, startChildIndex, stopChildIndex, t);
                }
        }

        public String toString(Object start, Object stop) {
        // we'll have to walk from start to stop in tree; we're not keeping
        // a complete node stream buffer
        return "n/a";
        }

    public String toTokenTypeString() {
        reset();
                StringBuffer buf = new StringBuffer();
        Object o = LT(1);
        int type = adaptor.getType(o);
        while ( type!=Token.EOF ) {
            buf.append(" ");
            buf.append(type);
            consume();
            o = LT(1);
            type = adaptor.getType(o);
                }
                return buf.toString();
    }
}

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