shared source/sscli20/jscript/engine/voidop.cs

   1 // ==++==
   2 //
   3 //
   4 //    Copyright (c) 2006 Microsoft Corporation.  All rights reserved.
   5 //
   6 //    The use and distribution terms for this software are contained in the file
   7 //    named license.txt, which can be found in the root of this distribution.
   8 //    By using this software in any fashion, you are agreeing to be bound by the
   9 //    terms of this license.
  10 //
  11 //    You must not remove this notice, or any other, from this software.
  12 //
  13 //
  14 // ==--==
  15
  16 namespace Microsoft.JScript {
  17
  18     using System;
  19     using System.Reflection;
  20     using System.Reflection.Emit;
  21
  22     internal sealed class VoidOp : UnaryOp{
  23
  24       internal VoidOp(Context context, AST operand)
  25         : base(context, operand) {
  26       }
  27
  28       internal override Object Evaluate(){
  29         this.operand.Evaluate();
  30         return null;
  31       }
  32
  33       internal override IReflect InferType(JSField inference_target){
  34         return Typeob.Empty;
  35       }
  36
  37       internal override AST PartiallyEvaluate(){
  38         return new ConstantWrapper(null, this.context);
  39       }
  40
  41       internal override void TranslateToIL(ILGenerator il, Type rtype){
  42         this.operand.TranslateToIL(il, Typeob.Object); //force evaluation
  43         if (rtype != Typeob.Void){
  44           il.Emit(OpCodes.Ldsfld, CompilerGlobals.undefinedField);
  45           Convert.Emit(this, il, Typeob.Object, rtype);
  46         }else
  47           il.Emit(OpCodes.Pop);
  48       }
  49
  50     }
  51 }