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                         if (Type.IsNullable ()) {
  56                                 EmitNullableConstant (ec, Type, value);
  57                                 return;
  58                         }
  59
  60                         EmitConstant (ec, Type, value);
  61                 }
  62
  63                 void EmitNullableConstant (EmitContext ec, Type type, object value)
  64                 {
  65                         if (value == null) {
  66                                 var ig = ec.ig;
  67                                 var local = ig.DeclareLocal (type);
  68                                 ig.Emit (OpCodes.Ldloca, local);
  69                                 ig.Emit (OpCodes.Initobj, type);
  70                                 ig.Emit (OpCodes.Ldloc, local);
  71                         } else {
  72                                 EmitConstant (ec, type.GetFirstGenericArgument (), value);
  73                                 ec.EmitNullableNew (type);
  74                         }
  75                 }
  76
  77                 void EmitConstant (EmitContext ec, Type type, object value)
  78                 {
  79                         var ig = ec.ig;
  80
  81                         switch (Type.GetTypeCode (type)){
  82                         case TypeCode.Byte:
  83                                 ig.Emit (OpCodes.Ldc_I4, (int) ((byte)value));
  84                                 return;
  85
  86                         case TypeCode.SByte:
  87                                 ig.Emit (OpCodes.Ldc_I4, (int) ((sbyte)value));
  88                                 return;
  89
  90                         case TypeCode.Int16:
  91                                 ig.Emit (OpCodes.Ldc_I4, (int) ((short)value));
  92                                 return;
  93
  94                         case TypeCode.UInt16:
  95                                 ig.Emit (OpCodes.Ldc_I4, (int) ((ushort)value));
  96                                 return;
  97
  98                         case TypeCode.Int32:
  99                                 ig.Emit (OpCodes.Ldc_I4, (int) value);
 100                                 return;
 101
 102                         case TypeCode.UInt32:
 103                                 ig.Emit (OpCodes.Ldc_I4, unchecked ((int) ((uint)Value)));
 104                                 return;
 105
 106                         case TypeCode.Int64:
 107                                 ig.Emit (OpCodes.Ldc_I8, (long) value);
 108                                 return;
 109
 110                         case TypeCode.UInt64:
 111                                 ig.Emit (OpCodes.Ldc_I8, unchecked ((long) ((ulong)value)));
 112                                 return;
 113
 114                         case TypeCode.Boolean:
 115                                 if ((bool) Value)
 116                                         ig.Emit (OpCodes.Ldc_I4_1);
 117                                 else
 118                                         ec.ig.Emit (OpCodes.Ldc_I4_0);
 119                                 return;
 120
 121                         case TypeCode.Char:
 122                                 ig.Emit (OpCodes.Ldc_I4, (int) ((char) value));
 123                                 return;
 124
 125                         case TypeCode.Single:
 126                                 ig.Emit (OpCodes.Ldc_R4, (float) value);
 127                                 return;
 128
 129                         case TypeCode.Double:
 130                                 ig.Emit (OpCodes.Ldc_R8, (double) value);
 131                                 return;
 132
 133                         case TypeCode.Decimal: {
 134                                 Decimal v = (decimal) value;
 135                                 int [] words = Decimal.GetBits (v);
 136                                 int power = (words [3] >> 16) & 0xff;
 137                                 Type ti = typeof (int);
 138
 139                                 if (power == 0 && v <= int.MaxValue && v >= int.MinValue) {
 140                                         ig.Emit (OpCodes.Ldc_I4, (int) v);
 141
 142                                         ig.Emit (OpCodes.Newobj, typeof (Decimal).GetConstructor (new Type [1] { ti }));
 143                                         return;
 144                                 }
 145                                 ig.Emit (OpCodes.Ldc_I4, words [0]);
 146                                 ig.Emit (OpCodes.Ldc_I4, words [1]);
 147                                 ig.Emit (OpCodes.Ldc_I4, words [2]);
 148                                 // sign
 149                                 ig.Emit (OpCodes.Ldc_I4, words [3] >> 31);
 150
 151                                 // power
 152                                 ig.Emit (OpCodes.Ldc_I4, power);
 153
 154                                 ig.Emit (OpCodes.Newobj, typeof (Decimal).GetConstructor (new Type [5] { ti, ti, ti, typeof(bool), typeof(byte) }));
 155                                 return;
 156                         }
 157
 158                         case TypeCode.DateTime: {
 159                                 var date = (DateTime) value;
 160                                 var local = ig.DeclareLocal (typeof (DateTime));
 161
 162                                 ig.Emit (OpCodes.Ldloca, local);
 163                                 ig.Emit (OpCodes.Ldc_I8, date.Ticks);
 164                                 ig.Emit (OpCodes.Ldc_I4, (int) date.Kind);
 165                                 ig.Emit (OpCodes.Call, typeof (DateTime).GetConstructor (new [] { typeof (long), typeof (DateTimeKind) }));
 166                                 ig.Emit (OpCodes.Ldloc, local);
 167
 168                                 return;
 169                         }
 170
 171                         case TypeCode.DBNull:
 172                                 ig.Emit (OpCodes.Ldsfld, typeof (DBNull).GetField ("Value", BindingFlags.Public | BindingFlags.Static));
 173                                 return;
 174
 175                         case TypeCode.String:
 176                                 EmitIfNotNull (ec, c => c.ig.Emit (OpCodes.Ldstr, (string) value));
 177                                 return;
 178
 179                         case TypeCode.Object:
 180                                 EmitIfNotNull (ec, c => c.EmitReadGlobal (value));
 181                                 return;
 182                         }
 183
 184                         throw new NotImplementedException (String.Format ("No support for constants of type {0} yet", Type));
 185                 }
 186
 187                 void EmitIfNotNull (EmitContext ec, Action<EmitContext> emit)
 188                 {
 189                         if (value == null) {
 190                                 ec.ig.Emit (OpCodes.Ldnull);
 191                                 return;
 192                         }
 193
 194                         emit (ec);
 195                 }
 196         }
 197 }