source: trunk/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory-5.5.0/Semantics/Conversion.cs @ 17197

// Copyright (c) 2010-2013 AlphaSierraPapa for the SharpDevelop Team
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
// software and associated documentation files (the "Software"), to deal in the Software
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// to whom the Software is furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in all copies or
// substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
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// DEALINGS IN THE SOFTWARE.

using System;
using ICSharpCode.NRefactory.TypeSystem;

namespace ICSharpCode.NRefactory.Semantics
{
  /// <summary>
  /// Holds information about a conversion between two types.
  /// </summary>
  public abstract class Conversion : IEquatable<Conversion>
  {
    #region Conversion factory methods
    /// <summary>
    /// Not a valid conversion.
    /// </summary>
    public static readonly Conversion None = new InvalidConversion();
    
    /// <summary>
    /// Identity conversion.
    /// </summary>
    public static readonly Conversion IdentityConversion = new BuiltinConversion(true, 0);
    
    public static readonly Conversion ImplicitNumericConversion = new NumericOrEnumerationConversion(true, false);
    public static readonly Conversion ExplicitNumericConversion = new NumericOrEnumerationConversion(false, false);
    public static readonly Conversion ImplicitLiftedNumericConversion = new NumericOrEnumerationConversion(true, true);
    public static readonly Conversion ExplicitLiftedNumericConversion = new NumericOrEnumerationConversion(false, true);
    
    public static Conversion EnumerationConversion(bool isImplicit, bool isLifted)
    {
      return new NumericOrEnumerationConversion(isImplicit, isLifted, true);
    }
    
    public static readonly Conversion NullLiteralConversion = new BuiltinConversion(true, 1);
    
    /// <summary>
    /// The numeric conversion of a constant expression.
    /// </summary>
    public static readonly Conversion ImplicitConstantExpressionConversion = new BuiltinConversion(true, 2);
    
    public static readonly Conversion ImplicitReferenceConversion = new BuiltinConversion(true, 3);
    public static readonly Conversion ExplicitReferenceConversion = new BuiltinConversion(false, 3);
    
    public static readonly Conversion ImplicitDynamicConversion = new BuiltinConversion(true, 4);
    public static readonly Conversion ExplicitDynamicConversion = new BuiltinConversion(false, 4);
    
    public static readonly Conversion ImplicitNullableConversion = new BuiltinConversion(true, 5);
    public static readonly Conversion ExplicitNullableConversion = new BuiltinConversion(false, 5);
    
    public static readonly Conversion ImplicitPointerConversion = new BuiltinConversion(true, 6);
    public static readonly Conversion ExplicitPointerConversion = new BuiltinConversion(false, 6);
    
    public static readonly Conversion BoxingConversion = new BuiltinConversion(true, 7);
    public static readonly Conversion UnboxingConversion = new BuiltinConversion(false, 8);
    
    /// <summary>
    /// C# 'as' cast.
    /// </summary>
    public static readonly Conversion TryCast = new BuiltinConversion(false, 9);
    
    [Obsolete("Use UserDefinedConversion() instead")]
    public static Conversion UserDefinedImplicitConversion(IMethod operatorMethod, Conversion conversionBeforeUserDefinedOperator, Conversion conversionAfterUserDefinedOperator, bool isLifted)
    {
      if (operatorMethod == null)
        throw new ArgumentNullException("operatorMethod");
      return new UserDefinedConv(true, operatorMethod, conversionBeforeUserDefinedOperator, conversionAfterUserDefinedOperator, isLifted, false);
    }
    
    [Obsolete("Use UserDefinedConversion() instead")]
    public static Conversion UserDefinedExplicitConversion(IMethod operatorMethod, Conversion conversionBeforeUserDefinedOperator, Conversion conversionAfterUserDefinedOperator, bool isLifted)
    {
      if (operatorMethod == null)
        throw new ArgumentNullException("operatorMethod");
      return new UserDefinedConv(false, operatorMethod, conversionBeforeUserDefinedOperator, conversionAfterUserDefinedOperator, isLifted, false);
    }
    
    public static Conversion UserDefinedConversion(IMethod operatorMethod, bool isImplicit, Conversion conversionBeforeUserDefinedOperator, Conversion conversionAfterUserDefinedOperator, bool isLifted = false, bool isAmbiguous = false)
    {
      if (operatorMethod == null)
        throw new ArgumentNullException("operatorMethod");
      return new UserDefinedConv(isImplicit, operatorMethod, conversionBeforeUserDefinedOperator, conversionAfterUserDefinedOperator, isLifted, isAmbiguous);
    }
    
    public static Conversion MethodGroupConversion(IMethod chosenMethod, bool isVirtualMethodLookup, bool delegateCapturesFirstArgument)
    {
      if (chosenMethod == null)
        throw new ArgumentNullException("chosenMethod");
      return new MethodGroupConv(chosenMethod, isVirtualMethodLookup, delegateCapturesFirstArgument, isValid: true);
    }
    
    public static Conversion InvalidMethodGroupConversion(IMethod chosenMethod, bool isVirtualMethodLookup, bool delegateCapturesFirstArgument)
    {
      if (chosenMethod == null)
        throw new ArgumentNullException("chosenMethod");
      return new MethodGroupConv(chosenMethod, isVirtualMethodLookup, delegateCapturesFirstArgument, isValid: false);
    }
    #endregion
    
    #region Inner classes
    sealed class InvalidConversion : Conversion
    {
      public override bool IsValid {
        get { return false; }
      }
      
      public override string ToString()
      {
        return "None";
      }
    }
    
    sealed class NumericOrEnumerationConversion : Conversion
    {
      readonly bool isImplicit;
      readonly bool isLifted;
      readonly bool isEnumeration;
      
      public NumericOrEnumerationConversion(bool isImplicit, bool isLifted, bool isEnumeration = false)
      {
        this.isImplicit = isImplicit;
        this.isLifted = isLifted;
        this.isEnumeration = isEnumeration;
      }
      
      public override bool IsImplicit {
        get { return isImplicit; }
      }
      
      public override bool IsExplicit {
        get { return !isImplicit; }
      }
      
      public override bool IsNumericConversion {
        get { return !isEnumeration; }
      }
      
      public override bool IsEnumerationConversion {
        get { return isEnumeration; }
      }
      
      public override bool IsLifted {
        get { return isLifted; }
      }
      
      public override string ToString()
      {
        return (isImplicit ? "implicit" : "explicit")
          + (isLifted ? " lifted" : "")
          + (isEnumeration ? " enumeration" : " numeric")
          + " conversion";
      }
      
      public override bool Equals(Conversion other)
      {
        NumericOrEnumerationConversion o = other as NumericOrEnumerationConversion;
        return o != null && isImplicit == o.isImplicit && isLifted == o.isLifted && isEnumeration == o.isEnumeration;
      }
      
      public override int GetHashCode()
      {
        return (isImplicit ? 1 : 0) + (isLifted ? 2 : 0) + (isEnumeration ? 4 : 0);
      }
    }
    
    sealed class BuiltinConversion : Conversion
    {
      readonly bool isImplicit;
      readonly byte type;
      
      public BuiltinConversion(bool isImplicit, byte type)
      {
        this.isImplicit = isImplicit;
        this.type = type;
      }
      
      public override bool IsImplicit {
        get { return isImplicit; }
      }
      
      public override bool IsExplicit {
        get { return !isImplicit; }
      }
      
      public override bool IsIdentityConversion {
        get { return type == 0; }
      }
      
      public override bool IsNullLiteralConversion {
        get { return type == 1; }
      }
      
      public override bool IsConstantExpressionConversion {
        get { return type == 2; }
      }

      public override bool IsReferenceConversion {
        get { return type == 3; }
      }
      
      public override bool IsDynamicConversion {
        get { return type == 4; }
      }
      
      public override bool IsNullableConversion {
        get { return type == 5; }
      }
      
      public override bool IsPointerConversion {
        get { return type == 6; }
      }
      
      public override bool IsBoxingConversion {
        get { return type == 7; }
      }
      
      public override bool IsUnboxingConversion {
        get { return type == 8; }
      }
      
      public override bool IsTryCast {
        get { return type == 9; }
      }
      
      public override string ToString()
      {
        string name = null;
        switch (type) {
          case 0:
            return "identity conversion";
          case 1:
            return "null-literal conversion";
          case 2:
            name = "constant-expression";
            break;
          case 3:
            name = "reference";
            break;
          case 4:
            name = "dynamic";
            break;
          case 5:
            name = "nullable";
            break;
          case 6:
            name = "pointer";
            break;
          case 7:
            return "boxing conversion";
          case 8:
            return "unboxing conversion";
          case 9:
            return "try cast";
        }
        return (isImplicit ? "implicit " : "explicit ") + name + " conversion";
      }
    }
    
    sealed class UserDefinedConv : Conversion
    {
      readonly IMethod method;
      readonly bool isLifted;
      readonly Conversion conversionBeforeUserDefinedOperator;
      readonly Conversion conversionAfterUserDefinedOperator;
      readonly bool isImplicit;
      readonly bool isValid;
      
      public UserDefinedConv(bool isImplicit, IMethod method, Conversion conversionBeforeUserDefinedOperator, Conversion conversionAfterUserDefinedOperator, bool isLifted, bool isAmbiguous)
      {
        this.method = method;
        this.isLifted = isLifted;
        this.conversionBeforeUserDefinedOperator = conversionBeforeUserDefinedOperator;
        this.conversionAfterUserDefinedOperator = conversionAfterUserDefinedOperator;
        this.isImplicit = isImplicit;
        this.isValid = !isAmbiguous;
      }
      
      public override bool IsValid {
        get { return isValid; }
      }
      
      public override bool IsImplicit {
        get { return isImplicit; }
      }
      
      public override bool IsExplicit {
        get { return !isImplicit; }
      }
      
      public override bool IsLifted {
        get { return isLifted; }
      }
      
      public override bool IsUserDefined {
        get { return true; }
      }
      
      public override Conversion ConversionBeforeUserDefinedOperator {
        get { return conversionBeforeUserDefinedOperator; }
      }
    
      public override Conversion ConversionAfterUserDefinedOperator {
        get { return conversionAfterUserDefinedOperator; }
      }

      public override IMethod Method {
        get { return method; }
      }
      
      public override bool Equals(Conversion other)
      {
        UserDefinedConv o = other as UserDefinedConv;
        return o != null && isLifted == o.isLifted && isImplicit == o.isImplicit && isValid == o.isValid && method.Equals(o.method);
      }
      
      public override int GetHashCode()
      {
        return unchecked(method.GetHashCode() + (isLifted ? 31 : 27) + (isImplicit ? 71 : 61) + (isValid ? 107 : 109));
      }
      
      public override string ToString()
      {
        return (isImplicit ? "implicit" : "explicit")
          + (isLifted ? " lifted" : "")
          + (isValid ? "" : " ambiguous")
          + "user-defined conversion (" + method + ")";
      }
    }
    
    sealed class MethodGroupConv : Conversion
    {
      readonly IMethod method;
      readonly bool isVirtualMethodLookup;
      readonly bool delegateCapturesFirstArgument;
      readonly bool isValid;
      
      public MethodGroupConv(IMethod method, bool isVirtualMethodLookup, bool delegateCapturesFirstArgument, bool isValid)
      {
        this.method = method;
        this.isVirtualMethodLookup = isVirtualMethodLookup;
        this.delegateCapturesFirstArgument = delegateCapturesFirstArgument;
        this.isValid = isValid;
      }
      
      public override bool IsValid {
        get { return isValid; }
      }
      
      public override bool IsImplicit {
        get { return true; }
      }
      
      public override bool IsMethodGroupConversion {
        get { return true; }
      }
      
      public override bool IsVirtualMethodLookup {
        get { return isVirtualMethodLookup; }
      }
      
      public override bool DelegateCapturesFirstArgument {
        get { return delegateCapturesFirstArgument; }
      }

      public override IMethod Method {
        get { return method; }
      }
      
      public override bool Equals(Conversion other)
      {
        MethodGroupConv o = other as MethodGroupConv;
        return o != null && method.Equals(o.method);
      }
      
      public override int GetHashCode()
      {
        return method.GetHashCode();
      }
    }
    #endregion
    
    /// <summary>
    /// Gets whether the conversion is valid.
    /// </summary>
    public virtual bool IsValid {
      get { return true; }
    }
    
    public virtual bool IsImplicit {
      get { return false; }
    }
    
    public virtual bool IsExplicit {
      get { return false; }
    }
    
    /// <summary>
    /// Gets whether the conversion is an '<c>as</c>' cast.
    /// </summary>
    public virtual bool IsTryCast {
      get { return false; }
    }
    
    public virtual bool IsIdentityConversion {
      get { return false; }
    }
    
    public virtual bool IsNullLiteralConversion {
      get { return false; }
    }
    
    public virtual bool IsConstantExpressionConversion {
      get { return false; }
    }

    public virtual bool IsNumericConversion {
      get { return false; }
    }
    
    /// <summary>
    /// Gets whether this conversion is a lifted version of another conversion.
    /// </summary>
    public virtual bool IsLifted {
      get { return false; }
    }
    
    /// <summary>
    /// Gets whether the conversion is dynamic.
    /// </summary>
    public virtual bool IsDynamicConversion {
      get { return false; }
    }
    
    /// <summary>
    /// Gets whether the conversion is a reference conversion.
    /// </summary>
    public virtual bool IsReferenceConversion {
      get { return false; }
    }
    
    /// <summary>
    /// Gets whether the conversion is an enumeration conversion.
    /// </summary>
    public virtual bool IsEnumerationConversion {
      get { return false; }
    }
    
    /// <summary>
    /// Gets whether the conversion is a nullable conversion
    /// (conversion between a nullable type and the regular type).
    /// </summary>
    public virtual bool IsNullableConversion {
      get { return false; }
    }
    
    /// <summary>
    /// Gets whether this conversion is user-defined (op_Implicit or op_Explicit).
    /// </summary>
    public virtual bool IsUserDefined {
      get { return false; }
    }

    /// <summary>
    /// The conversion that is applied to the input before the user-defined conversion operator is invoked.
    /// </summary>
    public virtual Conversion ConversionBeforeUserDefinedOperator {
      get { return null; }
    }
    
    /// <summary>
    /// The conversion that is applied to the result of the user-defined conversion operator.
    /// </summary>
    public virtual Conversion ConversionAfterUserDefinedOperator {
      get { return null; }
    }

    /// <summary>
    /// Gets whether this conversion is a boxing conversion.
    /// </summary>
    public virtual bool IsBoxingConversion {
      get { return false; }
    }
    
    /// <summary>
    /// Gets whether this conversion is an unboxing conversion.
    /// </summary>
    public virtual bool IsUnboxingConversion {
      get { return false; }
    }
    
    /// <summary>
    /// Gets whether this conversion is a pointer conversion.
    /// </summary>
    public virtual bool IsPointerConversion {
      get { return false; }
    }
    
    /// <summary>
    /// Gets whether this conversion is a method group conversion.
    /// </summary>
    public virtual bool IsMethodGroupConversion {
      get { return false; }
    }
    
    /// <summary>
    /// For method-group conversions, gets whether to perform a virtual method lookup at runtime.
    /// </summary>
    public virtual bool IsVirtualMethodLookup {
      get { return false; }
    }
    
    /// <summary>
    /// For method-group conversions, gets whether the conversion captures the first argument.
    /// 
    /// For instance methods, this property always returns true for C# method-group conversions.
    /// For static methods, this property returns true for method-group conversions of an extension method performed on an instance (eg. <c>Func&lt;int&gt; f = myEnumerable.Single</c>).
    /// </summary>
    public virtual bool DelegateCapturesFirstArgument {
      get { return false; }
    }

    /// <summary>
    /// Gets whether this conversion is an anonymous function conversion.
    /// </summary>
    public virtual bool IsAnonymousFunctionConversion {
      get { return false; }
    }
    
    /// <summary>
    /// Gets the method associated with this conversion.
    /// For user-defined conversions, this is the method being called.
    /// For method-group conversions, this is the method that was chosen from the group.
    /// </summary>
    public virtual IMethod Method {
      get { return null; }
    }
    
    public override sealed bool Equals(object obj)
    {
      return Equals(obj as Conversion);
    }
    
    public override int GetHashCode()
    {
      return base.GetHashCode();
    }
    
    public virtual bool Equals(Conversion other)
    {
      return this == other;
    }
  }
}