class/System.Core/System.Linq.Expressions/ConstantExpression.cs

   1 //
   2 // ConstantExpression.cs
   3 //
   4 // Author:
   5 //   Jb Evain (jbevain@novell.com)
   6 //   Miguel de Icaza (miguel@novell.com)
   7 //
   8 // Some code is based on the Mono C# compiler:
   9 //   Marek Safar (marek.safar@seznam.cz)
  10 //   Martin Baulig (martin@ximian.com)
  11 //
  12 // (C) 2001-2008 Novell, Inc. (http://www.novell.com)
  13 //
  14 // Permission is hereby granted, free of charge, to any person obtaining
  15 // a copy of this software and associated documentation files (the
  16 // "Software"), to deal in the Software without restriction, including
  17 // without limitation the rights to use, copy, modify, merge, publish,
  18 // distribute, sublicense, and/or sell copies of the Software, and to
  19 // permit persons to whom the Software is furnished to do so, subject to
  20 // the following conditions:
  21 //
  22 // The above copyright notice and this permission notice shall be
  23 // included in all copies or substantial portions of the Software.
  24 //
  25 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  26 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  27 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  28 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  29 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  30 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  31 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  32 //
  33
  34 using System;
  35 using System.Reflection;
  36 using System.Reflection.Emit;
  37
  38 namespace System.Linq.Expressions {
  39
  40         public sealed class ConstantExpression : Expression {
  41                 object value;
  42
  43                 public object Value {
  44                         get { return value; }
  45                 }
  46
  47                 internal ConstantExpression (object value, Type type)
  48                         : base (ExpressionType.Constant, type)
  49                 {
  50                         this.value = value;
  51                 }
  52
  53                 internal override void Emit (EmitContext ec)
  54                 {
  55                         ILGenerator ig = ec.ig;
  56
  57                         switch (Type.GetTypeCode (Type)){
  58                         case TypeCode.Byte:
  59                                 ig.Emit (OpCodes.Ldc_I4, (int) ((byte)value));
  60                                 return;
  61
  62                         case TypeCode.SByte:
  63                                 ig.Emit (OpCodes.Ldc_I4, (int) ((sbyte)value));
  64                                 return;
  65
  66                         case TypeCode.Int16:
  67                                 ig.Emit (OpCodes.Ldc_I4, (int) ((short)value));
  68                                 return;
  69
  70                         case TypeCode.UInt16:
  71                                 ig.Emit (OpCodes.Ldc_I4, (int) ((ushort)value));
  72                                 return;
  73
  74                         case TypeCode.Int32:
  75                                 ig.Emit (OpCodes.Ldc_I4, (int) value);
  76                                 return;
  77
  78                         case TypeCode.UInt32:
  79                                 ig.Emit (OpCodes.Ldc_I4, unchecked ((int) ((uint)Value)));
  80                                 return;
  81
  82                         case TypeCode.Int64:
  83                                 ig.Emit (OpCodes.Ldc_I8, (long) value);
  84                                 return;
  85
  86                         case TypeCode.UInt64:
  87                                 ig.Emit (OpCodes.Ldc_I8, unchecked ((long) ((ulong)value)));
  88                                 return;
  89
  90                         case TypeCode.Boolean:
  91                                 if ((bool) Value)
  92                                         ig.Emit (OpCodes.Ldc_I4_1);
  93                                 else
  94                                         ec.ig.Emit (OpCodes.Ldc_I4_0);
  95                                 return;
  96
  97                         case TypeCode.Char:
  98                                 ig.Emit (OpCodes.Ldc_I4, (int) ((char) value));
  99                                 return;
 100
 101                         case TypeCode.Single:
 102                                 ig.Emit (OpCodes.Ldc_R4, (float) value);
 103                                 return;
 104
 105                         case TypeCode.Double:
 106                                 ig.Emit (OpCodes.Ldc_R8, (double) value);
 107                                 return;
 108
 109                         case TypeCode.Decimal: {
 110                                 Decimal v = (decimal) value;
 111                                 int [] words = Decimal.GetBits (v);
 112                                 int power = (words [3] >> 16) & 0xff;
 113                                 Type ti = typeof (int);
 114
 115                                 if (power == 0 && v <= int.MaxValue && v >= int.MinValue) {
 116                                         ig.Emit (OpCodes.Ldc_I4, (int) v);
 117
 118                                         ig.Emit (OpCodes.Newobj, typeof (Decimal).GetConstructor (new Type [1] { ti }));
 119                                         return;
 120                                 }
 121                                 ig.Emit (OpCodes.Ldc_I4, words [0]);
 122                                 ig.Emit (OpCodes.Ldc_I4, words [1]);
 123                                 ig.Emit (OpCodes.Ldc_I4, words [2]);
 124                                 // sign
 125                                 ig.Emit (OpCodes.Ldc_I4, words [3] >> 31);
 126
 127                                 // power
 128                                 ig.Emit (OpCodes.Ldc_I4, power);
 129
 130                                 ig.Emit (OpCodes.Newobj, typeof (Decimal).GetConstructor (new Type [5] { ti, ti, ti, typeof(bool), typeof(byte) }));
 131                                 return;
 132                         }
 133
 134                         case TypeCode.DateTime: {
 135                                 var date = (DateTime) value;
 136                                 var local = ig.DeclareLocal (typeof (DateTime));
 137
 138                                 ig.Emit (OpCodes.Ldloca, local);
 139                                 ig.Emit (OpCodes.Ldc_I8, date.Ticks);
 140                                 ig.Emit (OpCodes.Ldc_I4, (int) date.Kind);
 141                                 ig.Emit (OpCodes.Call, typeof (DateTime).GetConstructor (new [] { typeof (long), typeof (DateTimeKind) }));
 142                                 ig.Emit (OpCodes.Ldloc, local);
 143
 144                                 return;
 145                         }
 146
 147                         case TypeCode.String:
 148                                 EmitIfNotNull (ec, c => c.ig.Emit (OpCodes.Ldstr, (string) value));
 149                                 return;
 150
 151                         case TypeCode.Object:
 152                                 EmitIfNotNull (ec, c => c.EmitReadGlobal (value));
 153                                 return;
 154                         }
 155
 156                         throw new NotImplementedException (String.Format ("No support for constants of type {0} yet", Type));
 157                 }
 158
 159                 void EmitIfNotNull (EmitContext ec, Action<EmitContext> emit)
 160                 {
 161                         if (value == null) {
 162                                 var ig = ec.ig;
 163
 164                                 if (Type.IsValueType) { // happens for nullable types
 165                                         var local = ig.DeclareLocal (Type);
 166                                         ig.Emit (OpCodes.Ldloca, local);
 167                                         ig.Emit (OpCodes.Initobj, Type);
 168                                         ig.Emit (OpCodes.Ldloc, local);
 169                                 } else {
 170                                         ec.ig.Emit (OpCodes.Ldnull);
 171                                 }
 172
 173                                 return;
 174                         }
 175
 176                         emit (ec);
 177                 }
 178         }
 179 }