mcs/class/Microsoft.JScript/Microsoft.JScript/PostOrPrefixOperator.cs

   1 //
   2 // PostOrPrefixOperator.cs:
   3 //
   4 // Author:
   5 //      Cesar Lopez Nataren (cesar@ciencias.unam.mx)
   6 //
   7 // (C) 2003, Cesar Lopez Nataren
   8 //
   9
  10 //
  11 // Permission is hereby granted, free of charge, to any person obtaining
  12 // a copy of this software and associated documentation files (the
  13 // "Software"), to deal in the Software without restriction, including
  14 // without limitation the rights to use, copy, modify, merge, publish,
  15 // distribute, sublicense, and/or sell copies of the Software, and to
  16 // permit persons to whom the Software is furnished to do so, subject to
  17 // the following conditions:
  18 //
  19 // The above copyright notice and this permission notice shall be
  20 // included in all copies or substantial portions of the Software.
  21 //
  22 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  23 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  24 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  25 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  26 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  27 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  28 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  29 //
  30
  31 using System;
  32 using System.Diagnostics;
  33 using System.Reflection.Emit;
  34
  35 namespace Microsoft.JScript {
  36
  37         public class PostOrPrefixOperator : UnaryOp {
  38
  39                 bool prefix;
  40
  41                 public PostOrPrefixOperator (int operatorTok)
  42                 {
  43                         oper = (JSToken) operatorTok;
  44                 }
  45
  46                 internal PostOrPrefixOperator (AST parent, AST operand, JSToken oper, bool prefix)
  47                 {
  48                         this.parent = parent;
  49                         this.operand = operand;
  50                         this.oper = oper;
  51                         this.prefix = prefix;
  52                 }
  53
  54                 [DebuggerStepThroughAttribute]
  55                 [DebuggerHiddenAttribute]
  56                 public object EvaluatePostOrPrefix (ref object v)
  57                 {
  58                         throw new NotImplementedException ();
  59                 }
  60
  61                 internal override bool Resolve (IdentificationTable context)
  62                 {
  63                         return operand.Resolve (context);
  64                 }
  65
  66                 internal override bool Resolve (IdentificationTable context, bool no_effect)
  67                 {
  68                         if (operand is Exp)
  69                                 return ((Exp) operand).Resolve (context, no_effect);
  70                         else
  71                                 return operand.Resolve (context);
  72                 }
  73
  74                 internal override void Emit (EmitContext ec)
  75                 {
  76                         if (oper == JSToken.None)
  77                                 operand.Emit (ec);
  78                         else {
  79                                 ILGenerator ig = ec.ig;
  80                                 Type post_prefix = typeof (PostOrPrefixOperator);
  81                                 LocalBuilder post_prefix_local = ig.DeclareLocal (post_prefix);
  82                                 LocalBuilder tmp_obj = ig.DeclareLocal (typeof (object));
  83
  84                                 switch (this.oper) {
  85                                 case JSToken.Increment:
  86                                         if (prefix)
  87                                                 ig.Emit (OpCodes.Ldc_I4_3);
  88                                         else
  89                                                 ig.Emit (OpCodes.Ldc_I4_1);
  90                                         break;
  91                                 case JSToken.Decrement:
  92                                         if (prefix)
  93                                                 ig.Emit (OpCodes.Ldc_I4_2);
  94                                         else
  95                                                 ig.Emit (OpCodes.Ldc_I4_0);
  96                                         break;
  97                                 }
  98
  99                                 ig.Emit (OpCodes.Newobj, post_prefix.GetConstructor (new Type [] { typeof (int) }));
 100                                 ig.Emit (OpCodes.Stloc, post_prefix_local);
 101
 102                                 if (operand is Identifier)
 103                                         ((Identifier) operand).EmitLoad (ec);
 104                                 else throw new NotImplementedException ();
 105
 106                                 ig.Emit (OpCodes.Stloc, tmp_obj);
 107                                 ig.Emit (OpCodes.Ldloc, post_prefix_local);
 108                                 ig.Emit (OpCodes.Ldloca_S, tmp_obj);
 109                                 ig.Emit (OpCodes.Call, post_prefix.GetMethod ("EvaluatePostOrPrefix"));
 110
 111                                 //
 112                                 // if does not appear as a global expression
 113                                 //
 114                                 if (prefix && !(parent is ScriptBlock)) {
 115                                         ig.Emit (OpCodes.Dup);
 116                                         ig.Emit (OpCodes.Stloc, tmp_obj);
 117                                 }
 118
 119                                 if (operand is Identifier)
 120                                         ((Identifier) operand).EmitStore (ec);
 121                                 else throw new NotImplementedException ();
 122
 123                                 //
 124                                 // If value will be used, load the
 125                                 // temp var that holded the value
 126                                 // before inc/dec was evaluated
 127                                 //
 128                                 if (!(parent is ScriptBlock || parent is FunctionDeclaration ||
 129                                       parent is FunctionExpression || parent is Block))
 130                                         ig.Emit (OpCodes.Ldloc, tmp_obj);
 131                         }
 132                 }
 133         }
 134 }