ILSpy/ICSharpCode.Decompiler/TypeSystem/SpecializingDecompilerTypeSystem.cs

// Copyright (c) 2014 Daniel Grunwald
// 
// 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
// without restriction, including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
// 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
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.

using System;
using System.Collections.Immutable;
using System.Reflection.Metadata;
using ICSharpCode.Decompiler.Metadata;

namespace ICSharpCode.Decompiler.TypeSystem
{
	/// <summary>
	/// Decompiler type system for generic types or methods:
	/// used to replace the dummy type parameters by the actual type parameters of the method being decompiled.
	/// </summary>
	public class SpecializingDecompilerTypeSystem : IDecompilerTypeSystem
	{
		readonly IDecompilerTypeSystem context;
		readonly TypeParameterSubstitution substitution;
		
		public SpecializingDecompilerTypeSystem(IDecompilerTypeSystem context, TypeParameterSubstitution substitution)
		{
			if (context == null)
				throw new ArgumentNullException(nameof(context));
			if (substitution == null)
				throw new ArgumentNullException(nameof(substitution));
			this.context = context;
			this.substitution = substitution;
		}

		internal IDecompilerTypeSystem Context {
			get { return context; }
		}
		
		public ICompilation Compilation {
			get { return context.Compilation; }
		}

		public Metadata.PEFile ModuleDefinition => context.ModuleDefinition;
		public MetadataModule MainModule => context.MainModule;

		public TypeParameterSubstitution Substitution {
			get { return substitution; }
		}
		
		public IType ResolveAsType(EntityHandle typeReference)
		{
			return context.ResolveAsType(typeReference).AcceptVisitor(substitution);
		}

		public IField ResolveAsField(EntityHandle fieldReference)
		{
			IField field = context.ResolveAsField(fieldReference);
			if (field != null)
				field = (IField)field.Specialize(substitution);
			return field;
		}

		public IMethod ResolveAsMethod(EntityHandle methodReference)
		{
			IMethod method = context.ResolveAsMethod(methodReference);
			if (method != null)
				method = (IMethod)method.Specialize(substitution);
			return method;
		}

		public IDecompilerTypeSystem GetSpecializingTypeSystem(TypeParameterSubstitution newSubstitution)
		{
			//return context.GetSpecializingTypeSystem(TypeParameterSubstitution.Compose(newSubstitution, this.substitution));
			// Because the input new substitution is taken from IMember.Substitution for some member that
			// was resolved by this type system, it already contains 'this.substitution'.
			return context.GetSpecializingTypeSystem(newSubstitution);
		}

		public MetadataReader GetMetadata()
		{
			return context.GetMetadata();
		}

		public IMember ResolveAsMember(EntityHandle memberReference)
		{
			IMember member = context.ResolveAsMember(memberReference);
			if (member != null)
				member = member.Specialize(substitution);
			return member;
		}
		
		MethodSignature<IType> IDecompilerTypeSystem.DecodeMethodSignature(StandaloneSignatureHandle standaloneSignatureHandle)
		{
			var sig = context.DecodeMethodSignature(standaloneSignatureHandle);
			return new MethodSignature<IType>(
				sig.Header,
				sig.ReturnType.AcceptVisitor(substitution),
				sig.RequiredParameterCount,
				sig.GenericParameterCount,
				ImmutableArray.CreateRange(
					sig.ParameterTypes, t => t.AcceptVisitor(substitution)
				)
			);
		}

		ImmutableArray<IType> IDecompilerTypeSystem.DecodeLocalSignature(StandaloneSignatureHandle standaloneSignatureHandle)
		{
			var sig = context.DecodeLocalSignature(standaloneSignatureHandle);
			return ImmutableArray.CreateRange(
				sig, t => t.AcceptVisitor(substitution)
			);
		}
	}
}