mcs/class/System.Core/System.Linq.Expressions/UnaryExpression.cs

   1 //
   2 // UnaryExpression.cs
   3 //
   4 // Author:
   5 //   Jb Evain (jbevain@novell.com)
   6 //
   7 // (C) 2008 Novell, Inc. (http://www.novell.com)
   8 //
   9 // Permission is hereby granted, free of charge, to any person obtaining
  10 // a copy of this software and associated documentation files (the
  11 // "Software"), to deal in the Software without restriction, including
  12 // without limitation the rights to use, copy, modify, merge, publish,
  13 // distribute, sublicense, and/or sell copies of the Software, and to
  14 // permit persons to whom the Software is furnished to do so, subject to
  15 // the following conditions:
  16 //
  17 // The above copyright notice and this permission notice shall be
  18 // included in all copies or substantial portions of the Software.
  19 //
  20 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  21 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  22 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  23 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  24 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  25 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  26 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  27 //
  28
  29 using System;
  30 using System.Reflection;
  31 using System.Reflection.Emit;
  32
  33 namespace System.Linq.Expressions {
  34
  35         public sealed class UnaryExpression : Expression {
  36
  37                 Expression operand;
  38                 MethodInfo method;
  39                 bool is_lifted;
  40
  41                 public Expression Operand {
  42                         get { return operand; }
  43                 }
  44
  45                 public MethodInfo Method {
  46                         get { return method; }
  47                 }
  48
  49                 public bool IsLifted {
  50                         get { return is_lifted; }
  51                 }
  52
  53                 public bool IsLiftedToNull {
  54                         get { return is_lifted && IsNullable (this.Type); }
  55                 }
  56
  57                 internal UnaryExpression (ExpressionType node_type, Expression operand, Type type)
  58                         : base (node_type, type)
  59                 {
  60                         this.operand = operand;
  61                 }
  62
  63                 internal UnaryExpression (ExpressionType node_type, Expression operand, Type type, MethodInfo method, bool is_lifted)
  64                         : base (node_type, type)
  65                 {
  66                         this.operand = operand;
  67                         this.method = method;
  68                         this.is_lifted = is_lifted;
  69                 }
  70
  71                 void EmitArrayLength (EmitContext ec)
  72                 {
  73                         operand.Emit (ec);
  74                         ec.ig.Emit (OpCodes.Ldlen);
  75                 }
  76
  77                 void EmitTypeAs (EmitContext ec)
  78                 {
  79                         var type = this.Type;
  80
  81                         ec.EmitIsInst (operand, type);
  82
  83                         if (IsNullable (type))
  84                                 ec.ig.Emit (OpCodes.Unbox_Any, type);
  85                 }
  86
  87                 void EmitUnaryOperator (EmitContext ec)
  88                 {
  89                         var ig = ec.ig;
  90
  91                         switch (NodeType) {
  92                         case ExpressionType.Not:
  93                                 if (GetNotNullableOf (operand.Type) == typeof (bool)) {
  94                                         ig.Emit (OpCodes.Ldc_I4_0);
  95                                         ig.Emit (OpCodes.Ceq);
  96                                 } else
  97                                         ig.Emit (OpCodes.Not);
  98                                 break;
  99                         case ExpressionType.Negate:
 100                         case ExpressionType.NegateChecked:
 101                                 ig.Emit (OpCodes.Neg);
 102                                 break;
 103                         }
 104                 }
 105
 106                 void EmitConvert (EmitContext ec)
 107                 {
 108                         if (Type == operand.Type)
 109                                 return;
 110
 111                         operand.Emit (ec);
 112
 113                         if (IsCast ())
 114                                 EmitCast (ec);
 115                         else
 116                                 throw new NotImplementedException ();
 117                 }
 118
 119                 bool IsCast ()
 120                 {
 121                         return CheckReferenceConversion (operand.Type, Type);
 122                 }
 123
 124                 bool IsBoxing ()
 125                 {
 126                         return operand.Type.IsValueType && !Type.IsValueType;
 127                 }
 128
 129                 bool IsUnBoxing ()
 130                 {
 131                         return !operand.Type.IsValueType && Type.IsValueType;
 132                 }
 133
 134                 void EmitCast (EmitContext ec)
 135                 {
 136                         var ig = ec.ig;
 137
 138                         if (IsBoxing ()) {
 139                                 ig.Emit (OpCodes.Box, Type);
 140                         } else if (IsUnBoxing ()) {
 141                                 ig.Emit (OpCodes.Unbox_Any, Type);
 142                         } else
 143                                 ec.ig.Emit (OpCodes.Castclass, Type);
 144                 }
 145
 146                 internal override void Emit (EmitContext ec)
 147                 {
 148                         switch (this.NodeType) {
 149                         case ExpressionType.ArrayLength:
 150                                 EmitArrayLength (ec);
 151                                 return;
 152                         case ExpressionType.TypeAs:
 153                                 EmitTypeAs (ec);
 154                                 return;
 155                         case ExpressionType.Not:
 156                         case ExpressionType.Negate:
 157                         case ExpressionType.NegateChecked:
 158                         case ExpressionType.UnaryPlus:
 159                                 if (!is_lifted) {
 160                                         operand.Emit (ec);
 161                                         EmitUnaryOperator (ec);
 162                                 } else
 163                                         throw new NotImplementedException ();
 164                                 return;
 165                         case ExpressionType.Convert:
 166                         case ExpressionType.ConvertChecked:
 167                                 EmitConvert (ec);
 168                                 return;
 169                         default:
 170                                 throw new NotImplementedException (this.NodeType.ToString ());
 171                         }
 172                 }
 173         }
 174 }