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      1 /*
      2  [The "BSD license"]
      3  Copyright (c) 2005-2009 Terence Parr
      4  All rights reserved.
      5 
      6  Redistribution and use in source and binary forms, with or without
      7  modification, are permitted provided that the following conditions
      8  are met:
      9  1. Redistributions of source code must retain the above copyright
     10      notice, this list of conditions and the following disclaimer.
     11  2. Redistributions in binary form must reproduce the above copyright
     12      notice, this list of conditions and the following disclaimer in the
     13      documentation and/or other materials provided with the distribution.
     14  3. The name of the author may not be used to endorse or promote products
     15      derived from this software without specific prior written permission.
     16 
     17  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     18  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     19  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     20  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     21  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     22  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     23  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     24  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     26  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 package org.antlr.runtime.tree;
     29 
     30 import org.antlr.runtime.Token;
     31 import org.antlr.runtime.TokenStream;
     32 import org.antlr.runtime.misc.LookaheadStream;
     33 import org.antlr.runtime.misc.IntArray;
     34 
     35 import java.util.*;
     36 
     37 public class CommonTreeNodeStream extends LookaheadStream<Object> implements TreeNodeStream {
     38 	public static final int DEFAULT_INITIAL_BUFFER_SIZE = 100;
     39 	public static final int INITIAL_CALL_STACK_SIZE = 10;
     40 
     41 	/** Pull nodes from which tree? */
     42 	protected Object root;
     43 
     44 	/** If this tree (root) was created from a token stream, track it. */
     45 	protected TokenStream tokens;
     46 
     47 	/** What tree adaptor was used to build these trees */
     48 	TreeAdaptor adaptor;
     49 
     50     /** The tree iterator we using */
     51     protected TreeIterator it;
     52 
     53     /** Stack of indexes used for push/pop calls */
     54     protected IntArray calls;
     55 
     56     /** Tree (nil A B C) trees like flat A B C streams */
     57     protected boolean hasNilRoot = false;
     58 
     59     /** Tracks tree depth.  Level=0 means we're at root node level. */
     60     protected int level = 0;
     61 
     62 	public CommonTreeNodeStream(Object tree) {
     63 		this(new CommonTreeAdaptor(), tree);
     64 	}
     65 
     66 	public CommonTreeNodeStream(TreeAdaptor adaptor, Object tree) {
     67 		this.root = tree;
     68 		this.adaptor = adaptor;
     69         it = new TreeIterator(adaptor,root);
     70 	}
     71 
     72     public void reset() {
     73         super.reset();
     74         it.reset();
     75         hasNilRoot = false;
     76         level = 0;
     77         if ( calls != null ) calls.clear();
     78     }
     79 
     80     /** Pull elements from tree iterator.  Track tree level 0..max_level.
     81      *  If nil rooted tree, don't give initial nil and DOWN nor final UP.
     82      */
     83     public Object nextElement() {
     84         Object t = it.next();
     85         //System.out.println("pulled "+adaptor.getType(t));
     86         if ( t == it.up ) {
     87             level--;
     88             if ( level==0 && hasNilRoot ) return it.next(); // don't give last UP; get EOF
     89         }
     90         else if ( t == it.down ) level++;
     91         if ( level==0 && adaptor.isNil(t) ) { // if nil root, scarf nil, DOWN
     92             hasNilRoot = true;
     93             t = it.next(); // t is now DOWN, so get first real node next
     94             level++;
     95             t = it.next();
     96         }
     97         return t;
     98     }
     99 
    100     public boolean isEOF(Object o) { return adaptor.getType(o) == Token.EOF; }
    101 
    102     public void setUniqueNavigationNodes(boolean uniqueNavigationNodes) { }
    103 
    104 	public Object getTreeSource() {	return root; }
    105 
    106 	public String getSourceName() { return getTokenStream().getSourceName(); }
    107 
    108 	public TokenStream getTokenStream() { return tokens; }
    109 
    110 	public void setTokenStream(TokenStream tokens) { this.tokens = tokens; }
    111 
    112 	public TreeAdaptor getTreeAdaptor() { return adaptor; }
    113 
    114 	public void setTreeAdaptor(TreeAdaptor adaptor) { this.adaptor = adaptor; }
    115 
    116     public Object get(int i) {
    117         throw new UnsupportedOperationException("Absolute node indexes are meaningless in an unbuffered stream");
    118     }
    119 
    120     public int LA(int i) { return adaptor.getType(LT(i)); }
    121 
    122     /** Make stream jump to a new location, saving old location.
    123      *  Switch back with pop().
    124      */
    125     public void push(int index) {
    126         if ( calls==null ) {
    127             calls = new IntArray();
    128         }
    129         calls.push(p); // save current index
    130         seek(index);
    131     }
    132 
    133     /** Seek back to previous index saved during last push() call.
    134      *  Return top of stack (return index).
    135      */
    136     public int pop() {
    137         int ret = calls.pop();
    138         seek(ret);
    139         return ret;
    140     }
    141 
    142 	// TREE REWRITE INTERFACE
    143 
    144 	public void replaceChildren(Object parent, int startChildIndex, int stopChildIndex, Object t) {
    145 		if ( parent!=null ) {
    146 			adaptor.replaceChildren(parent, startChildIndex, stopChildIndex, t);
    147 		}
    148 	}
    149 
    150 	public String toString(Object start, Object stop) {
    151         // we'll have to walk from start to stop in tree; we're not keeping
    152         // a complete node stream buffer
    153         return "n/a";
    154 	}
    155 
    156     /** For debugging; destructive: moves tree iterator to end. */
    157     public String toTokenTypeString() {
    158         reset();
    159 		StringBuffer buf = new StringBuffer();
    160         Object o = LT(1);
    161         int type = adaptor.getType(o);
    162         while ( type!=Token.EOF ) {
    163             buf.append(" ");
    164             buf.append(type);
    165             consume();
    166             o = LT(1);
    167             type = adaptor.getType(o);
    168 		}
    169 		return buf.toString();
    170     }
    171 }
    172