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> 38 * How to execute code for node t when a visitor visits node t. Execute 39 * pre() before visiting children and execute post() after visiting children. 40 * </summary> 41 */ 42 public interface ITreeVisitorAction 43 { 44 /** <summary> 45 * Execute an action before visiting children of t. Return t or 46 * a rewritten t. It is up to the visitor to decide what to do 47 * with the return value. Children of returned value will be 48 * visited if using TreeVisitor.visit(). 49 * </summary> 50 */ Pre( object t )51 object Pre( object t ); 52 53 /** <summary> 54 * Execute an action after visiting children of t. Return t or 55 * a rewritten t. It is up to the visitor to decide what to do 56 * with the return value. 57 * </summary> 58 */ Post( object t )59 object Post( object t ); 60 } 61 62 public class TreeVisitorAction 63 : ITreeVisitorAction 64 { 65 private readonly Func<object, object> _preAction; 66 private readonly Func<object, object> _postAction; 67 TreeVisitorAction( Func<object, object> preAction, Func<object, object> postAction )68 public TreeVisitorAction( Func<object, object> preAction, Func<object, object> postAction ) 69 { 70 _preAction = preAction; 71 _postAction = postAction; 72 } 73 Pre( object t )74 public object Pre( object t ) 75 { 76 if ( _preAction != null ) 77 return _preAction( t ); 78 79 return t; 80 } 81 Post( object t )82 public object Post( object t ) 83 { 84 if ( _postAction != null ) 85 return _postAction( t ); 86 87 return t; 88 } 89 } 90 } 91