src/Boo.Lang.Compiler/Steps/ProcessAssignmentsToSpecialMembers.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 namespace Boo.Lang.Compiler.Steps
  30 {
  31         using Boo.Lang.Compiler.Ast;
  32         using Boo.Lang.Compiler.TypeSystem;
  33
  34         /// <summary>
  35         /// Summary description for ProcessAssignmentsToSpecialMembers.
  36         /// </summary>
  37         public abstract class ProcessAssignmentsToSpecialMembers : AbstractTransformerCompilerStep
  38         {
  39                 Method _currentMethod;
  40
  41                 override public void Run()
  42                 {
  43                         if (0 == Errors.Count)
  44                         {
  45                                 Visit(CompileUnit);
  46                         }
  47                 }
  48
  49                 override public void OnInterfaceDefinition(InterfaceDefinition node)
  50                 {
  51                 }
  52
  53                 override public void OnEnumDefinition(EnumDefinition node)
  54                 {
  55                 }
  56
  57                 override public void OnMethod(Method node)
  58                 {
  59                         _currentMethod = node;
  60                         Visit(node.Body);
  61                 }
  62
  63                 override public void OnConstructor(Constructor node)
  64                 {
  65                         OnMethod(node);
  66                 }
  67
  68                 override public void LeaveBinaryExpression(BinaryExpression node)
  69                 {
  70                         if (IsAssignmentToSpecialMember(node))
  71                         {
  72                                 ProcessAssignmentToSpecialMember(node);
  73                         }
  74                 }
  75
  76                 protected bool IsAssignmentToSpecialMember(BinaryExpression node)
  77                 {
  78                         if (BinaryOperatorType.Assign == node.Operator &&
  79                                 NodeType.MemberReferenceExpression == node.Left.NodeType)
  80                         {
  81                                 MemberReferenceExpression memberRef = node.Left as MemberReferenceExpression;
  82                                 Expression target = memberRef.Target;
  83                                 return !IsTerminalReferenceNode(target)
  84                                         && IsSpecialMemberTarget(target);
  85                         }
  86                         return false;
  87                 }
  88
  89                 protected abstract bool IsSpecialMemberTarget(Expression container);
  90
  91                 public class ChainItem
  92                 {
  93                         public Expression Container;
  94                         public InternalLocal Local;
  95
  96                         public ChainItem(Expression container)
  97                         {
  98                                 this.Container = container;
  99                         }
 100                 }
 101
 102                 void ProcessAssignmentToSpecialMember(BinaryExpression node)
 103                 {
 104                         MemberReferenceExpression memberRef = (MemberReferenceExpression)node.Left;
 105                         List chain = WalkMemberChain(memberRef);
 106                         if (null == chain || 0 == chain.Count) return;
 107
 108                         MethodInvocationExpression eval = CodeBuilder.CreateEvalInvocation(node.LexicalInfo);
 109
 110                         // right hand side should always be executed before
 111                         // left hand side
 112                         InternalLocal value = DeclareTempLocal(GetExpressionType(node.Right));
 113                         eval.Arguments.Add(
 114                                 CodeBuilder.CreateAssignment(
 115                                 CodeBuilder.CreateReference(value),
 116                                 node.Right));
 117
 118                         foreach (ChainItem item in chain)
 119                         {
 120                                 item.Local = DeclareTempLocal(item.Container.ExpressionType);
 121                                 BinaryExpression tempInitialization = CodeBuilder.CreateAssignment(
 122                                         node.LexicalInfo,
 123                                         CodeBuilder.CreateReference(item.Local),
 124                                         item.Container.CloneNode());
 125                                 item.Container.ParentNode.Replace(item.Container,
 126                                         CodeBuilder.CreateReference(item.Local));
 127                                 eval.Arguments.Add(tempInitialization);
 128                         }
 129
 130                         eval.Arguments.Add(
 131                                 CodeBuilder.CreateAssignment(node.LexicalInfo,
 132                                 node.Left,
 133                                 CodeBuilder.CreateReference(value)));
 134
 135                         PropagateChanges(eval, chain);
 136
 137                         if (NodeType.ExpressionStatement != node.ParentNode.NodeType)
 138                         {
 139                                 eval.Arguments.Add(CodeBuilder.CreateReference(value));
 140                                 BindExpressionType(eval, value.Type);
 141                         }
 142
 143                         ReplaceCurrentNode(eval);
 144                 }
 145
 146                 protected virtual void PropagateChanges(MethodInvocationExpression eval, List chain)
 147                 {
 148                         foreach (ChainItem item in chain.Reversed)
 149                         {
 150                                 eval.Arguments.Add(
 151                                         CodeBuilder.CreateAssignment(
 152                                         item.Container.CloneNode(),
 153                                         CodeBuilder.CreateReference(item.Local)));
 154                         }
 155                 }
 156
 157                 protected virtual List WalkMemberChain(MemberReferenceExpression memberRef)
 158                 {
 159                         List chain = new List();
 160                         while (true)
 161                         {
 162                                 MemberReferenceExpression container = memberRef.Target as MemberReferenceExpression;
 163                                 if (null == container ||
 164                                         (IsSpecialMemberTarget(container)
 165                                         && IsReadOnlyMember(container)))
 166                                 {
 167                                         Warnings.Add(
 168                                                 CompilerWarningFactory.AssignmentToTemporary(memberRef));
 169                                         return null;
 170                                 }
 171                                 if (IsSpecialMemberTarget(container)
 172                                         && EntityType.Field != container.Entity.EntityType)
 173                                 {
 174                                         chain.Insert(0, new ChainItem(container));
 175                                 }
 176                                 if (IsTerminalReferenceNode(container.Target))
 177                                 {
 178                                         break;
 179                                 }
 180                                 memberRef = container;
 181                         }
 182                         return chain;
 183                 }
 184
 185                 protected virtual bool IsTerminalReferenceNode(Expression target)
 186                 {
 187                         NodeType type = target.NodeType;
 188                         return
 189                                 NodeType.ReferenceExpression == type ||
 190                                 NodeType.SelfLiteralExpression == type ||
 191                                 NodeType.SuperLiteralExpression == type ||
 192                                 ProcessMethodBodies.IsArraySlicing(target) ||
 193                                 !IsSpecialMemberTarget(target);
 194                 }
 195
 196                 protected virtual bool IsReadOnlyMember(MemberReferenceExpression container)
 197                 {
 198                         switch (container.Entity.EntityType)
 199                         {
 200                                 case EntityType.Property:
 201                                 {
 202                                         return ((IProperty)container.Entity).GetSetMethod() == null;
 203                                 }
 204                                 case EntityType.Field:
 205                                 {
 206                                         return TypeSystemServices.IsReadOnlyField((IField)container.Entity);
 207                                 }
 208                         }
 209                         return true;
 210                 }
 211
 212                 InternalLocal DeclareTempLocal(IType localType)
 213                 {
 214                         return CodeBuilder.DeclareTempLocal(_currentMethod, localType);
 215                 }
 216         }
 217 }