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.IntStream; 31 import org.antlr.runtime.TokenStream; 32 33 /** A stream of tree nodes, accessing nodes from a tree of some kind */ 34 public interface TreeNodeStream extends IntStream { 35 /** Get a tree node at an absolute index i; 0..n-1. 36 * If you don't want to buffer up nodes, then this method makes no 37 * sense for you. 38 */ 39 public Object get(int i); 40 41 /** Get tree node at current input pointer + i ahead where i=1 is next node. 42 * i<0 indicates nodes in the past. So LT(-1) is previous node, but 43 * implementations are not required to provide results for k < -1. 44 * LT(0) is undefined. For i>=n, return null. 45 * Return null for LT(0) and any index that results in an absolute address 46 * that is negative. 47 * 48 * This is analogus to the LT() method of the TokenStream, but this 49 * returns a tree node instead of a token. Makes code gen identical 50 * for both parser and tree grammars. :) 51 */ 52 public Object LT(int k); 53 54 /** Where is this stream pulling nodes from? This is not the name, but 55 * the object that provides node objects. 56 */ 57 public Object getTreeSource(); 58 59 /** If the tree associated with this stream was created from a TokenStream, 60 * you can specify it here. Used to do rule $text attribute in tree 61 * parser. Optional unless you use tree parser rule text attribute 62 * or output=template and rewrite=true options. 63 */ 64 public TokenStream getTokenStream(); 65 66 /** What adaptor can tell me how to interpret/navigate nodes and 67 * trees. E.g., get text of a node. 68 */ 69 public TreeAdaptor getTreeAdaptor(); 70 71 /** As we flatten the tree, we use UP, DOWN nodes to represent 72 * the tree structure. When debugging we need unique nodes 73 * so we have to instantiate new ones. When doing normal tree 74 * parsing, it's slow and a waste of memory to create unique 75 * navigation nodes. Default should be false; 76 */ 77 public void setUniqueNavigationNodes(boolean uniqueNavigationNodes); 78 79 /** Reset the tree node stream in such a way that it acts like 80 * a freshly constructed stream. 81 */ 82 public void reset(); 83 84 /** Return the text of all nodes from start to stop, inclusive. 85 * If the stream does not buffer all the nodes then it can still 86 * walk recursively from start until stop. You can always return 87 * null or "" too, but users should not access $ruleLabel.text in 88 * an action of course in that case. 89 */ 90 public String toString(Object start, Object stop); 91 92 93 // REWRITING TREES (used by tree parser) 94 95 /** Replace from start to stop child index of parent with t, which might 96 * be a list. Number of children may be different 97 * after this call. The stream is notified because it is walking the 98 * tree and might need to know you are monkeying with the underlying 99 * tree. Also, it might be able to modify the node stream to avoid 100 * restreaming for future phases. 101 * 102 * If parent is null, don't do anything; must be at root of overall tree. 103 * Can't replace whatever points to the parent externally. Do nothing. 104 */ 105 public void replaceChildren(Object parent, int startChildIndex, int stopChildIndex, Object t); 106 } 107