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| 1 | +// Copyright (c) 2025 Daniel Grunwald |
| 2 | +// |
| 3 | +// Permission is hereby granted, free of charge, to any person obtaining a copy of this |
| 4 | +// software and associated documentation files (the "Software"), to deal in the Software |
| 5 | +// without restriction, including without limitation the rights to use, copy, modify, merge, |
| 6 | +// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons |
| 7 | +// to whom the Software is furnished to do so, subject to the following conditions: |
| 8 | +// |
| 9 | +// The above copyright notice and this permission notice shall be included in all copies or |
| 10 | +// substantial portions of the Software. |
| 11 | +// |
| 12 | +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, |
| 13 | +// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR |
| 14 | +// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE |
| 15 | +// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR |
| 16 | +// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER |
| 17 | +// DEALINGS IN THE SOFTWARE. |
| 18 | + |
| 19 | +#nullable enable |
| 20 | + |
| 21 | +using System.Collections.Generic; |
| 22 | +using System.Linq; |
| 23 | +using System.Reflection.Metadata; |
| 24 | + |
| 25 | +namespace ICSharpCode.Decompiler.TypeSystem |
| 26 | +{ |
| 27 | + public class ExtensionInfo |
| 28 | + { |
| 29 | + readonly Dictionary<IMember, ExtensionMemberInfo> extensionMemberMap; |
| 30 | + readonly Dictionary<IMember, ExtensionMemberInfo> implementationMemberMap; |
| 31 | + |
| 32 | + public ExtensionInfo(MetadataModule module, ITypeDefinition extensionContainer) |
| 33 | + { |
| 34 | + this.extensionMemberMap = new(); |
| 35 | + this.implementationMemberMap = new(); |
| 36 | + |
| 37 | + var metadata = module.MetadataFile.Metadata; |
| 38 | + |
| 39 | + foreach (var extGroup in extensionContainer.NestedTypes) |
| 40 | + { |
| 41 | + if (!(extGroup is { Kind: TypeKind.Class, IsSealed: true } |
| 42 | + && extGroup.Name.StartsWith("<>E__", System.StringComparison.Ordinal))) |
| 43 | + { |
| 44 | + continue; |
| 45 | + } |
| 46 | + |
| 47 | + TypeDefinition td = metadata.GetTypeDefinition((TypeDefinitionHandle)extGroup.MetadataToken); |
| 48 | + IMethod? marker = null; |
| 49 | + bool hasMultipleMarkers = false; |
| 50 | + List<IMethod> extensionMethods = []; |
| 51 | + |
| 52 | + // For easier access to accessors we use SRM |
| 53 | + foreach (var h in td.GetMethods()) |
| 54 | + { |
| 55 | + var method = module.GetDefinition(h); |
| 56 | + |
| 57 | + if (method.SymbolKind is SymbolKind.Constructor) |
| 58 | + continue; |
| 59 | + if (method is { Name: "<Extension>$", IsStatic: true, Parameters.Count: 1 }) |
| 60 | + { |
| 61 | + if (marker == null) |
| 62 | + marker = method; |
| 63 | + else |
| 64 | + hasMultipleMarkers = true; |
| 65 | + continue; |
| 66 | + } |
| 67 | + |
| 68 | + extensionMethods.Add(method); |
| 69 | + } |
| 70 | + |
| 71 | + if (marker == null || hasMultipleMarkers) |
| 72 | + continue; |
| 73 | + |
| 74 | + foreach (var extension in extensionMethods) |
| 75 | + { |
| 76 | + int expectedTypeParameterCount = extension.TypeParameters.Count + extGroup.TypeParameterCount; |
| 77 | + bool hasInstance = !extension.IsStatic; |
| 78 | + int parameterOffset = hasInstance ? 1 : 0; |
| 79 | + int expectedParameterCount = extension.Parameters.Count + parameterOffset; |
| 80 | + TypeParameterSubstitution subst = new TypeParameterSubstitution([], [.. extGroup.TypeArguments, .. extension.TypeArguments]); |
| 81 | + |
| 82 | + bool IsMatchingImplementation(IMethod impl) |
| 83 | + { |
| 84 | + if (!impl.IsStatic) |
| 85 | + return false; |
| 86 | + if (extension.Name != impl.Name) |
| 87 | + return false; |
| 88 | + if (expectedTypeParameterCount != impl.TypeParameters.Count) |
| 89 | + return false; |
| 90 | + if (expectedParameterCount != impl.Parameters.Count) |
| 91 | + return false; |
| 92 | + if (hasInstance) |
| 93 | + { |
| 94 | + IType ti = impl.Parameters[0].Type.AcceptVisitor(subst); |
| 95 | + IType tm = marker.Parameters.Single().Type; |
| 96 | + if (!NormalizeTypeVisitor.TypeErasure.EquivalentTypes(ti, tm)) |
| 97 | + return false; |
| 98 | + } |
| 99 | + for (int i = 0; i < extension.Parameters.Count; i++) |
| 100 | + { |
| 101 | + IType ti = impl.Parameters[i + parameterOffset].Type.AcceptVisitor(subst); |
| 102 | + IType tm = extension.Parameters[i].Type; |
| 103 | + if (!NormalizeTypeVisitor.TypeErasure.EquivalentTypes(ti, tm)) |
| 104 | + return false; |
| 105 | + } |
| 106 | + return NormalizeTypeVisitor.TypeErasure.EquivalentTypes( |
| 107 | + impl.ReturnType.AcceptVisitor(subst), |
| 108 | + extension.ReturnType |
| 109 | + ); |
| 110 | + } |
| 111 | + |
| 112 | + foreach (var impl in extensionContainer.Methods) |
| 113 | + { |
| 114 | + if (!IsMatchingImplementation(impl)) |
| 115 | + continue; |
| 116 | + var emi = new ExtensionMemberInfo(marker, extension, impl); |
| 117 | + extensionMemberMap[extension] = emi; |
| 118 | + implementationMemberMap[impl] = emi; |
| 119 | + } |
| 120 | + } |
| 121 | + } |
| 122 | + |
| 123 | + } |
| 124 | + |
| 125 | + public ExtensionMemberInfo? InfoOfExtensionMember(IMethod method) |
| 126 | + { |
| 127 | + return this.extensionMemberMap.TryGetValue(method, out var value) ? value : null; |
| 128 | + } |
| 129 | + |
| 130 | + public ExtensionMemberInfo? InfoOfImplementationMember(IMethod method) |
| 131 | + { |
| 132 | + return this.implementationMemberMap.TryGetValue(method, out var value) ? value : null; |
| 133 | + } |
| 134 | + |
| 135 | + public IEnumerable<IGrouping<IMethod, ExtensionMemberInfo>> GetGroups() |
| 136 | + { |
| 137 | + return this.extensionMemberMap.Values.GroupBy(x => x.ExtensionMarkerMethod); |
| 138 | + } |
| 139 | + } |
| 140 | + |
| 141 | + public readonly struct ExtensionMemberInfo(IMethod marker, IMethod extension, IMethod implementation) |
| 142 | + { |
| 143 | + /// <summary> |
| 144 | + /// Metadata-only method called '<Extension>$'. Has the C# signature for the extension declaration. |
| 145 | + /// |
| 146 | + /// <code>extension(ReceiverType name) {} -> void <Extension>$(ReceiverType name) {}</code> |
| 147 | + /// </summary> |
| 148 | + public readonly IMethod ExtensionMarkerMethod = marker; |
| 149 | + /// <summary> |
| 150 | + /// Metadata-only method with a signature as declared in C# within the extension declaration. |
| 151 | + /// This could also be an accessor of an extension property. |
| 152 | + /// </summary> |
| 153 | + public readonly IMethod ExtensionMember = extension; |
| 154 | + /// <summary> |
| 155 | + /// The actual implementation method in the outer class. The signature is a concatenation |
| 156 | + /// of the extension marker and the extension member's signatures. |
| 157 | + /// </summary> |
| 158 | + public readonly IMethod ImplementationMethod = implementation; |
| 159 | + |
| 160 | + /// <summary> |
| 161 | + /// This is the enclosing static class. |
| 162 | + /// </summary> |
| 163 | + public ITypeDefinition ExtensionContainer => ImplementationMethod.DeclaringTypeDefinition!; |
| 164 | + |
| 165 | + /// <summary> |
| 166 | + /// This is the compiler-generated class containing the extension members. Has type parameters |
| 167 | + /// from the extension declaration with minimal constraints. |
| 168 | + /// </summary> |
| 169 | + public ITypeDefinition ExtensionGroupingType => ExtensionMember.DeclaringTypeDefinition!; |
| 170 | + |
| 171 | + /// <summary> |
| 172 | + /// This class holds the type parameters for the extension declaration with full fidelity of C# constraints. |
| 173 | + /// </summary> |
| 174 | + public ITypeDefinition ExtensionMarkerType => ExtensionMarkerMethod.DeclaringTypeDefinition!; |
| 175 | + } |
| 176 | +} |
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