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.CommonToken; 32 import org.antlr.runtime.misc.FastQueue; 33 34 import java.util.Iterator; 35 36 /** Return a node stream from a doubly-linked tree whose nodes 37 * know what child index they are. No remove() is supported. 38 * 39 * Emit navigation nodes (DOWN, UP, and EOF) to let show tree structure. 40 */ 41 public class TreeIterator implements Iterator { 42 protected TreeAdaptor adaptor; 43 protected Object root; 44 protected Object tree; 45 protected boolean firstTime = true; 46 47 // navigation nodes to return during walk and at end 48 public Object up; 49 public Object down; 50 public Object eof; 51 52 /** If we emit UP/DOWN nodes, we need to spit out multiple nodes per 53 * next() call. 54 */ 55 protected FastQueue nodes; 56 TreeIterator(Object tree)57 public TreeIterator(Object tree) { 58 this(new CommonTreeAdaptor(),tree); 59 } 60 TreeIterator(TreeAdaptor adaptor, Object tree)61 public TreeIterator(TreeAdaptor adaptor, Object tree) { 62 this.adaptor = adaptor; 63 this.tree = tree; 64 this.root = tree; 65 nodes = new FastQueue(); 66 down = adaptor.create(Token.DOWN, "DOWN"); 67 up = adaptor.create(Token.UP, "UP"); 68 eof = adaptor.create(Token.EOF, "EOF"); 69 } 70 reset()71 public void reset() { 72 firstTime = true; 73 tree = root; 74 nodes.clear(); 75 } 76 hasNext()77 public boolean hasNext() { 78 if ( firstTime ) return root!=null; 79 if ( nodes!=null && nodes.size()>0 ) return true; 80 if ( tree==null ) return false; 81 if ( adaptor.getChildCount(tree)>0 ) return true; 82 return adaptor.getParent(tree)!=null; // back at root? 83 } 84 next()85 public Object next() { 86 if ( firstTime ) { // initial condition 87 firstTime = false; 88 if ( adaptor.getChildCount(tree)==0 ) { // single node tree (special) 89 nodes.add(eof); 90 return tree; 91 } 92 return tree; 93 } 94 // if any queued up, use those first 95 if ( nodes!=null && nodes.size()>0 ) return nodes.remove(); 96 97 // no nodes left? 98 if ( tree==null ) return eof; 99 100 // next node will be child 0 if any children 101 if ( adaptor.getChildCount(tree)>0 ) { 102 tree = adaptor.getChild(tree, 0); 103 nodes.add(tree); // real node is next after DOWN 104 return down; 105 } 106 // if no children, look for next sibling of tree or ancestor 107 Object parent = adaptor.getParent(tree); 108 // while we're out of siblings, keep popping back up towards root 109 while ( parent!=null && 110 adaptor.getChildIndex(tree)+1 >= adaptor.getChildCount(parent) ) 111 { 112 nodes.add(up); // we're moving back up 113 tree = parent; 114 parent = adaptor.getParent(tree); 115 } 116 // no nodes left? 117 if ( parent==null ) { 118 tree = null; // back at root? nothing left then 119 nodes.add(eof); // add to queue, might have UP nodes in there 120 return nodes.remove(); 121 } 122 123 // must have found a node with an unvisited sibling 124 // move to it and return it 125 int nextSiblingIndex = adaptor.getChildIndex(tree) + 1; 126 tree = adaptor.getChild(parent, nextSiblingIndex); 127 nodes.add(tree); // add to queue, might have UP nodes in there 128 return nodes.remove(); 129 } 130 remove()131 public void remove() { throw new UnsupportedOperationException(); } 132 } 133