src/Boo.Lang.Compiler/Ast/DepthFirstTransformer.cs

   1 #region license
   2 // Copyright (c) 2003, 2004, 2005 Rodrigo B. de Oliveira (rbo@acm.org)
   3 // All rights reserved.
   4 //
   5 // Redistribution and use in source and binary forms, with or without modification,
   6 // are permitted provided that the following conditions are met:
   7 //
   8 //     * Redistributions of source code must retain the above copyright notice,
   9 //     this list of conditions and the following disclaimer.
  10 //     * Redistributions in binary form must reproduce the above copyright notice,
  11 //     this list of conditions and the following disclaimer in the documentation
  12 //     and/or other materials provided with the distribution.
  13 //     * Neither the name of Rodrigo B. de Oliveira nor the names of its
  14 //     contributors may be used to endorse or promote products derived from this
  15 //     software without specific prior written permission.
  16 //
  17 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
  18 // ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  19 // WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  20 // DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
  21 // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22 // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  23 // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  24 // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  25 // OR TORT (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 #endregion
  28
  29
  30 using System;
  31 using System.Collections.Generic;
  32 using System.Text;
  33
  34 namespace Boo.Lang.Compiler.Ast
  35 {
  36         public partial class DepthFirstTransformer
  37         {
  38                 protected Node _resultingNode = null;
  39
  40                 protected virtual void RemoveCurrentNode()
  41                 {
  42                         _resultingNode = null;
  43                 }
  44
  45                 protected virtual void ReplaceCurrentNode(Node replacement)
  46                 {
  47                         _resultingNode = replacement;
  48                 }
  49
  50                 protected virtual void OnNode(Node node)
  51                 {
  52                         node.Accept(this);
  53                 }
  54
  55                 public virtual Node VisitNode(Node node)
  56                 {
  57                         if (null != node)
  58                         {
  59                                 try
  60                                 {
  61                                         Node saved = _resultingNode;
  62                                         _resultingNode = node;
  63                                         OnNode(node);
  64                                         Node result = _resultingNode;
  65                                         _resultingNode = saved;
  66                                         return result;
  67                                 }
  68                                 catch (Boo.Lang.Compiler.CompilerError)
  69                                 {
  70                                         throw;
  71                                 }
  72                                 catch (Exception error)
  73                                 {
  74                                         OnError(node, error);
  75                                 }
  76                         }
  77                         return null;
  78                 }
  79
  80                 protected virtual void OnError(Node node, Exception error)
  81                 {
  82                         throw Boo.Lang.Compiler.CompilerErrorFactory.InternalError(node, error);
  83                 }
  84
  85                 public Node Visit(Node node)
  86                 {
  87                         return VisitNode(node);
  88                 }
  89
  90                 public Expression Visit(Expression node)
  91                 {
  92                         return (Expression)VisitNode(node);
  93                 }
  94
  95                 public Statement Visit(Statement node)
  96                 {
  97                         return (Statement)VisitNode(node);
  98                 }
  99
 100                 public bool Visit<T>(NodeCollection<T> collection) where T : Node
 101                 {
 102                         if (null == collection) return false;
 103
 104                         int removed = 0;
 105
 106                         T[] nodes = collection.ToArray();
 107                         for (int i = 0; i < nodes.Length; ++i)
 108                         {
 109                                 T currentNode = nodes[i];
 110                                 T resultingNode = (T)VisitNode(currentNode);
 111                                 if (currentNode != resultingNode)
 112                                 {
 113                                         int actualIndex = i - removed;
 114                                         if (null == resultingNode)
 115                                         {
 116                                                 ++removed;
 117                                                 collection.RemoveAt(actualIndex);
 118                                         }
 119                                         else
 120                                         {
 121                                                 collection.ReplaceAt(actualIndex, resultingNode);
 122                                         }
 123                                 }
 124                         }
 125                         return true;
 126                 }
 127         }
 128 }