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

   1 //
   2 // ParameterExpression.cs
   3 //
   4 // Author:
   5 //   Jb Evain (jbevain@novell.com)
   6 //   Miguel de Icaza (miguel@novell.com)
   7 //
   8 // (C) 2008 Novell, Inc. (http://www.novell.com)
   9 //
  10 // Permission is hereby granted, free of charge, to any person obtaining
  11 // a copy of this software and associated documentation files (the
  12 // "Software"), to deal in the Software without restriction, including
  13 // without limitation the rights to use, copy, modify, merge, publish,
  14 // distribute, sublicense, and/or sell copies of the Software, and to
  15 // permit persons to whom the Software is furnished to do so, subject to
  16 // the following conditions:
  17 //
  18 // The above copyright notice and this permission notice shall be
  19 // included in all copies or substantial portions of the Software.
  20 //
  21 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  22 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  23 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  24 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  25 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  26 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  27 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  28 //
  29
  30 using System;
  31 using System.Reflection.Emit;
  32
  33 namespace System.Linq.Expressions {
  34
  35         public sealed class ParameterExpression : Expression {
  36
  37                 string name;
  38
  39                 public string Name {
  40                         get { return name; }
  41                 }
  42
  43                 internal ParameterExpression (Type type, string name)
  44                         : base (ExpressionType.Parameter, type)
  45                 {
  46                         this.name = name;
  47                 }
  48
  49                 void EmitLocalParameter (EmitContext ec, int position)
  50                 {
  51                         ec.ig.Emit (OpCodes.Ldarg, position);
  52                 }
  53
  54                 void EmitHoistedLocal (EmitContext ec, int level, int position)
  55                 {
  56                         ec.EmitScope ();
  57
  58                         for (int i = 0; i < level; i++)
  59                                 ec.EmitParentScope ();
  60
  61                         ec.EmitLoadLocals ();
  62
  63                         ec.ig.Emit (OpCodes.Ldc_I4, position);
  64                         ec.ig.Emit (OpCodes.Ldelem, typeof (object));
  65
  66                         ec.EmitLoadStrongBoxValue (Type);
  67                 }
  68
  69                 internal override void Emit (EmitContext ec)
  70                 {
  71                         int position = -1;
  72                         if (ec.IsLocalParameter (this, ref position)) {
  73                                 EmitLocalParameter (ec, position);
  74                                 return;
  75                         }
  76
  77                         int level = 0;
  78                         if (ec.IsHoistedLocal (this, ref level, ref position)) {
  79                                 EmitHoistedLocal (ec, level, position);
  80                                 return;
  81                         }
  82
  83                         throw new InvalidOperationException ("Parameter out of scope");
  84                 }
  85         }
  86 }