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.debug; 29 30 import org.antlr.runtime.RecognitionException; 31 import org.antlr.runtime.Token; 32 import org.antlr.runtime.tree.ParseTree; 33 34 import java.util.Stack; 35 import java.util.ArrayList; 36 import java.util.List; 37 38 /** This parser listener tracks rule entry/exit and token matches 39 * to build a simple parse tree using ParseTree nodes. 40 */ 41 public class ParseTreeBuilder extends BlankDebugEventListener { 42 public static final String EPSILON_PAYLOAD = "<epsilon>"; 43 44 Stack<ParseTree> callStack = new Stack<ParseTree>(); 45 List<Token> hiddenTokens = new ArrayList<Token>(); 46 int backtracking = 0; 47 ParseTreeBuilder(String grammarName)48 public ParseTreeBuilder(String grammarName) { 49 ParseTree root = create("<grammar "+grammarName+">"); 50 callStack.push(root); 51 } 52 getTree()53 public ParseTree getTree() { 54 return callStack.elementAt(0); 55 } 56 57 /** What kind of node to create. You might want to override 58 * so I factored out creation here. 59 */ create(Object payload)60 public ParseTree create(Object payload) { 61 return new ParseTree(payload); 62 } 63 epsilonNode()64 public ParseTree epsilonNode() { 65 return create(EPSILON_PAYLOAD); 66 } 67 68 /** Backtracking or cyclic DFA, don't want to add nodes to tree */ 69 @Override enterDecision(int d, boolean couldBacktrack)70 public void enterDecision(int d, boolean couldBacktrack) { backtracking++; } 71 @Override exitDecision(int i)72 public void exitDecision(int i) { backtracking--; } 73 74 @Override enterRule(String filename, String ruleName)75 public void enterRule(String filename, String ruleName) { 76 if ( backtracking>0 ) return; 77 ParseTree parentRuleNode = callStack.peek(); 78 ParseTree ruleNode = create(ruleName); 79 parentRuleNode.addChild(ruleNode); 80 callStack.push(ruleNode); 81 } 82 83 @Override exitRule(String filename, String ruleName)84 public void exitRule(String filename, String ruleName) { 85 if ( backtracking>0 ) return; 86 ParseTree ruleNode = callStack.peek(); 87 if ( ruleNode.getChildCount()==0 ) { 88 ruleNode.addChild(epsilonNode()); 89 } 90 callStack.pop(); 91 } 92 93 @Override consumeToken(Token token)94 public void consumeToken(Token token) { 95 if ( backtracking>0 ) return; 96 ParseTree ruleNode = callStack.peek(); 97 ParseTree elementNode = create(token); 98 elementNode.hiddenTokens = this.hiddenTokens; 99 this.hiddenTokens = new ArrayList<Token>(); 100 ruleNode.addChild(elementNode); 101 } 102 103 @Override consumeHiddenToken(Token token)104 public void consumeHiddenToken(Token token) { 105 if ( backtracking>0 ) return; 106 hiddenTokens.add(token); 107 } 108 109 @Override recognitionException(RecognitionException e)110 public void recognitionException(RecognitionException e) { 111 if ( backtracking>0 ) return; 112 ParseTree ruleNode = callStack.peek(); 113 ParseTree errorNode = create(e); 114 ruleNode.addChild(errorNode); 115 } 116 } 117