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.RecognizerSharedState; 31 import org.antlr.runtime.RecognitionException; 32 import org.antlr.runtime.TokenStream; 33 34 public class TreeRewriter extends TreeParser { 35 public interface fptr { rule()36 public Object rule() throws RecognitionException; 37 } 38 39 protected boolean showTransformations = false; 40 41 protected TokenStream originalTokenStream; 42 protected TreeAdaptor originalAdaptor; 43 TreeRewriter(TreeNodeStream input)44 public TreeRewriter(TreeNodeStream input) { 45 this(input, new RecognizerSharedState()); 46 } TreeRewriter(TreeNodeStream input, RecognizerSharedState state)47 public TreeRewriter(TreeNodeStream input, RecognizerSharedState state) { 48 super(input, state); 49 originalAdaptor = input.getTreeAdaptor(); 50 originalTokenStream = input.getTokenStream(); 51 } 52 applyOnce(Object t, fptr whichRule)53 public Object applyOnce(Object t, fptr whichRule) { 54 if ( t==null ) return null; 55 try { 56 // share TreeParser object but not parsing-related state 57 state = new RecognizerSharedState(); 58 input = new CommonTreeNodeStream(originalAdaptor, t); 59 ((CommonTreeNodeStream)input).setTokenStream(originalTokenStream); 60 setBacktrackingLevel(1); 61 TreeRuleReturnScope r = (TreeRuleReturnScope)whichRule.rule(); 62 setBacktrackingLevel(0); 63 if ( failed() ) return t; 64 if ( showTransformations && 65 r!=null && !t.equals(r.getTree()) && r.getTree()!=null ) 66 { 67 reportTransformation(t, r.getTree()); 68 } 69 if ( r!=null && r.getTree()!=null ) return r.getTree(); 70 else return t; 71 } 72 catch (RecognitionException e) { ; } 73 return t; 74 } 75 applyRepeatedly(Object t, fptr whichRule)76 public Object applyRepeatedly(Object t, fptr whichRule) { 77 boolean treeChanged = true; 78 while ( treeChanged ) { 79 Object u = applyOnce(t, whichRule); 80 treeChanged = !t.equals(u); 81 t = u; 82 } 83 return t; 84 } 85 downup(Object t)86 public Object downup(Object t) { return downup(t, false); } 87 downup(Object t, boolean showTransformations)88 public Object downup(Object t, boolean showTransformations) { 89 this.showTransformations = showTransformations; 90 TreeVisitor v = new TreeVisitor(new CommonTreeAdaptor()); 91 TreeVisitorAction actions = new TreeVisitorAction() { 92 public Object pre(Object t) { return applyOnce(t, topdown_fptr); } 93 public Object post(Object t) { return applyRepeatedly(t, bottomup_ftpr); } 94 }; 95 t = v.visit(t, actions); 96 return t; 97 } 98 99 /** Override this if you need transformation tracing to go somewhere 100 * other than stdout or if you're not using Tree-derived trees. 101 */ reportTransformation(Object oldTree, Object newTree)102 public void reportTransformation(Object oldTree, Object newTree) { 103 System.out.println(((Tree)oldTree).toStringTree()+" -> "+ 104 ((Tree)newTree).toStringTree()); 105 } 106 107 fptr topdown_fptr = new fptr() { 108 public Object rule() throws RecognitionException { return topdown(); } 109 }; 110 111 fptr bottomup_ftpr = new fptr() { 112 public Object rule() throws RecognitionException { return bottomup(); } 113 }; 114 115 // methods the downup strategy uses to do the up and down rules. 116 // to override, just define tree grammar rule topdown and turn on 117 // filter=true. topdown()118 public Object topdown() throws RecognitionException { return null; } bottomup()119 public Object bottomup() throws RecognitionException { return null; } 120 } 121