shared source/sscli20/jscript/engine/jslocalfield.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.Collections;
  20     using System.Globalization;
  21     using System.Reflection;
  22
  23     public sealed class JSLocalField : JSVariableField{
  24       internal int slotNumber;
  25       internal IReflect inferred_type; //Records a guess of what the type of the field is. null = unknown.
  26       private ArrayList dependents; //A list of other fields whose types have been inferred (guessed) based on the inferred type of this field.
  27                                     //The dependend fields need to have their guesses changed.
  28       internal bool debugOn; // whether this local field was in a section of code with debug set or not. Control emitting debug info for the local
  29       internal JSLocalField outerField; //If this field is a copy of an outer scope field, the outer scope field is kept in here.
  30       internal bool isDefined; //Indicates whether an assignment to the field has been encountered.
  31       internal bool isUsedBeforeDefinition;
  32
  33       public JSLocalField(String name, RuntimeTypeHandle handle, int slotNumber)
  34         : this(name, null, slotNumber, Missing.Value){
  35         this.type = new TypeExpression(new ConstantWrapper(Type.GetTypeFromHandle(handle), null));
  36         this.isDefined = true;
  37       }
  38
  39       internal JSLocalField(String name, FunctionScope scope, int slotNumber, Object value)
  40         : base(name, scope, FieldAttributes.Static|FieldAttributes.Public) {
  41         this.slotNumber = slotNumber;
  42         this.inferred_type = null;
  43         this.dependents = null;
  44         this.value = value;
  45         this.debugOn = false;
  46         this.outerField = null;
  47         this.isDefined = false;
  48         this.isUsedBeforeDefinition = false;
  49       }
  50
  51       public override Type FieldType{
  52         get{
  53           if (this.type != null)
  54             return base.FieldType;
  55           else
  56             return Convert.ToType(this.GetInferredType(null));
  57         }
  58       }
  59
  60       internal override IReflect GetInferredType(JSField inference_target){
  61         if (this.outerField != null)
  62           return this.outerField.GetInferredType(inference_target);
  63         if (this.type != null)
  64           return base.GetInferredType(inference_target);
  65         if (this.inferred_type == null || this.inferred_type == Typeob.Object)
  66           return Typeob.Object;
  67         if (inference_target != null && inference_target != this){
  68           if (this.dependents == null)
  69             this.dependents = new ArrayList();
  70           this.dependents.Add(inference_target);
  71         }
  72         return this.inferred_type;
  73       }
  74
  75       public override Object GetValue(Object obj){
  76         if ((this.attributeFlags&FieldAttributes.Literal) != (FieldAttributes)0 && !(this.value is FunctionObject))
  77           return this.value;
  78         else{
  79           while (obj is BlockScope) obj = ((BlockScope)obj).GetParent();
  80           StackFrame sf = (StackFrame)obj;
  81           JSLocalField f = this.outerField;
  82           int slot = this.slotNumber;
  83           while (f != null){
  84             slot = f.slotNumber;
  85             sf = (StackFrame)sf.GetParent();
  86             f = f.outerField;
  87           }
  88           return sf.localVars[slot];
  89         }
  90       }
  91
  92       internal void SetInferredType(IReflect ir, AST expr){
  93         this.isDefined = true;
  94         if (this.type != null)
  95           return; //The local variable has a type annotation.
  96         if (this.outerField != null){
  97           this.outerField.SetInferredType(ir, expr);
  98           return;
  99         }
 100         if (Convert.IsPrimitiveNumericTypeFitForDouble(ir))
 101           ir = Typeob.Double;
 102         else if (ir == Typeob.Void)
 103           ir = Typeob.Object;
 104         if (this.inferred_type == null)
 105           this.inferred_type = ir;
 106         else{
 107           //Check to see if ir is compatible with this.inferred_type. If not, generalize this.inferred_type to Object and invalidate dependants.
 108           if (ir == this.inferred_type) return;
 109           if (!Convert.IsPrimitiveNumericType(this.inferred_type) || !Convert.IsPrimitiveNumericType(ir) ||
 110               !Convert.IsPromotableTo(ir, this.inferred_type)){
 111             this.inferred_type = Typeob.Object;
 112             if (this.dependents != null)
 113               for (int i = 0, n = this.dependents.Count; i < n; i++)
 114                 ((JSLocalField)this.dependents[i]).SetInferredType(Typeob.Object, null);
 115           }
 116         }
 117       }
 118
 119       public override void SetValue(Object obj, Object value, BindingFlags invokeAttr, Binder binder, CultureInfo locale){
 120         if (this.type != null)
 121           value = Convert.Coerce(value, this.type);
 122         while (obj is BlockScope) obj = ((BlockScope)obj).GetParent();
 123         StackFrame sf = (StackFrame)obj;
 124         JSLocalField f = this.outerField;
 125         int slot = this.slotNumber;
 126         while (f != null){
 127           slot = f.slotNumber;
 128           sf = (StackFrame)sf.GetParent();
 129           f = f.outerField;
 130         }
 131         if (sf.localVars == null) return; //happens when assigning to a constant from latebound code
 132         sf.localVars[slot] = value;
 133       }
 134    }
 135 }