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 /** <summary>Do a depth first walk of a tree, applying pre() and post() actions as we go.</summary> */ 36 public class TreeVisitor 37 { 38 protected ITreeAdaptor adaptor; 39 40 public TreeVisitor(ITreeAdaptor adaptor) 41 { 42 this.adaptor = adaptor; 43 } 44 public TreeVisitor() 45 : this(new CommonTreeAdaptor()) 46 { 47 } 48 49 /** <summary> 50 * Visit every node in tree t and trigger an action for each node 51 * before/after having visited all of its children. Bottom up walk. 52 * Execute both actions even if t has no children. Ignore return 53 * results from transforming children since they will have altered 54 * the child list of this node (their parent). Return result of 55 * applying post action to this node. 56 * </summary> 57 */ 58 public object Visit(object t, ITreeVisitorAction action) 59 { 60 // System.out.println("visit "+((Tree)t).toStringTree()); 61 bool isNil = adaptor.IsNil(t); 62 if (action != null && !isNil) 63 { 64 t = action.Pre(t); // if rewritten, walk children of new t 65 } 66 for (int i = 0; i < adaptor.GetChildCount(t); i++) 67 { 68 object child = adaptor.GetChild(t, i); 69 Visit(child, action); 70 } 71 if (action != null && !isNil) 72 t = action.Post(t); 73 return t; 74 } 75 76 public object Visit(object t, Func<object, object> preAction, Func<object, object> postAction) 77 { 78 return Visit(t, new TreeVisitorAction(preAction, postAction)); 79 } 80 } 81 } 82
