1 /* 2 * [The "BSD licence"] 3 * Copyright (c) 2005-2008 Terence Parr 4 * All rights reserved. 5 * 6 * Conversion to C#: 7 * Copyright (c) 2008-2009 Sam Harwell, Pixel Mine, Inc. 8 * All rights reserved. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. The name of the author may not be used to endorse or promote products 19 * derived from this software without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 namespace Antlr.Runtime.Tree 34 { 35 using Antlr.Runtime.Misc; 36 37 /** <summary>Do a depth first walk of a tree, applying pre() and post() actions as we go.</summary> */ 38 public class TreeVisitor 39 { 40 protected ITreeAdaptor adaptor; 41 TreeVisitor( ITreeAdaptor adaptor )42 public TreeVisitor( ITreeAdaptor adaptor ) 43 { 44 this.adaptor = adaptor; 45 } TreeVisitor()46 public TreeVisitor() 47 : this( new CommonTreeAdaptor() ) 48 { 49 } 50 51 /** <summary> 52 * Visit every node in tree t and trigger an action for each node 53 * before/after having visited all of its children. Bottom up walk. 54 * Execute both actions even if t has no children. Ignore return 55 * results from transforming children since they will have altered 56 * the child list of this node (their parent). Return result of 57 * applying post action to this node. 58 * </summary> 59 */ Visit( object t, ITreeVisitorAction action )60 public object Visit( object t, ITreeVisitorAction action ) 61 { 62 // System.out.println("visit "+((Tree)t).toStringTree()); 63 bool isNil = adaptor.IsNil( t ); 64 if ( action != null && !isNil ) 65 { 66 t = action.Pre( t ); // if rewritten, walk children of new t 67 } 68 for ( int i = 0; i < adaptor.GetChildCount(t); i++ ) 69 { 70 object child = adaptor.GetChild( t, i ); 71 Visit( child, action ); 72 } 73 if ( action != null && !isNil ) 74 t = action.Post( t ); 75 return t; 76 } 77 Visit( object t, Func<object, object> preAction, Func<object, object> postAction )78 public object Visit( object t, Func<object, object> preAction, Func<object, object> postAction ) 79 { 80 return Visit( t, new TreeVisitorAction( preAction, postAction ) ); 81 } 82 } 83 } 84