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 
CommonTreeNodeStream(Object tree)62 	public CommonTreeNodeStream(Object tree) {
63 		this(new CommonTreeAdaptor(), tree);
64 	}
65 
CommonTreeNodeStream(TreeAdaptor adaptor, Object tree)66 	public CommonTreeNodeStream(TreeAdaptor adaptor, Object tree) {
67 		this.root = tree;
68 		this.adaptor = adaptor;
69         it = new TreeIterator(adaptor,root);
70 	}
71 
reset()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      */
nextElement()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 
isEOF(Object o)100     public boolean isEOF(Object o) { return adaptor.getType(o) == Token.EOF; }
101 
setUniqueNavigationNodes(boolean uniqueNavigationNodes)102     public void setUniqueNavigationNodes(boolean uniqueNavigationNodes) { }
103 
getTreeSource()104 	public Object getTreeSource() {	return root; }
105 
getSourceName()106 	public String getSourceName() { return getTokenStream().getSourceName(); }
107 
getTokenStream()108 	public TokenStream getTokenStream() { return tokens; }
109 
setTokenStream(TokenStream tokens)110 	public void setTokenStream(TokenStream tokens) { this.tokens = tokens; }
111 
getTreeAdaptor()112 	public TreeAdaptor getTreeAdaptor() { return adaptor; }
113 
setTreeAdaptor(TreeAdaptor adaptor)114 	public void setTreeAdaptor(TreeAdaptor adaptor) { this.adaptor = adaptor; }
115 
get(int i)116     public Object get(int i) {
117         throw new UnsupportedOperationException("Absolute node indexes are meaningless in an unbuffered stream");
118     }
119 
LA(int i)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      */
push(int index)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      */
pop()136     public int pop() {
137         int ret = calls.pop();
138         seek(ret);
139         return ret;
140     }
141 
142 	// TREE REWRITE INTERFACE
143 
replaceChildren(Object parent, int startChildIndex, int stopChildIndex, Object t)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 
toString(Object start, Object stop)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. */
toTokenTypeString()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