78 lines
3.4 KiB
C#
78 lines
3.4 KiB
C#
// Licensed to the .NET Foundation under one or more agreements.
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// The .NET Foundation licenses this file to you under the MIT license.
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// See the LICENSE file in the project root for more information.
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using System.IO;
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using System.Linq;
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using System.Reflection;
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using CommunityToolkit.Mvvm.SourceGenerators.Extensions;
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using Microsoft.CodeAnalysis;
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namespace CommunityToolkit.Mvvm.SourceGenerators;
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/// <summary>
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/// A source generator for necessary nullability attributes.
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/// </summary>
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[Generator(LanguageNames.CSharp)]
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public sealed class NullabilityAttributesGenerator : IIncrementalGenerator
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{
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/// <summary>
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/// The <c>System.Diagnostics.CodeAnalysis.NotNullAttribute</c> metadata name.
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/// </summary>
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private const string NotNullAttributeMetadataName = "System.Diagnostics.CodeAnalysis.NotNullAttribute";
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/// <summary>
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/// The <c>System.Diagnostics.CodeAnalysis.NotNullIfNotNullAttribute</c> metadata name.
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/// </summary>
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private const string NotNullIfNotNullAttributeMetadataName = "System.Diagnostics.CodeAnalysis.NotNullIfNotNullAttribute";
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/// <inheritdoc/>
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public void Initialize(IncrementalGeneratorInitializationContext context)
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{
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// Check that the target attributes are not available in the consuming project. To ensure that this
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// works fine both in .NET (Core) and .NET Standard implementations, we also need to check that the
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// target types are declared as public (we assume that in this case those types are from the BCL).
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// This avoids issues on .NET Standard with Roslyn also seeing internal types from referenced assemblies.
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// Check whether [NotNull] is not available
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IncrementalValueProvider<bool> isNotNullAttributeNotAvailable =
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context.CompilationProvider
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.Select(static (item, _) => !item.HasAccessibleTypeWithMetadataName(NotNullAttributeMetadataName));
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// Generate the [NotNull] type
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context.RegisterConditionalSourceOutput(isNotNullAttributeNotAvailable, static context =>
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{
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string source = LoadAttributeSourceWithMetadataName(NotNullAttributeMetadataName);
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context.AddSource($"{NotNullAttributeMetadataName}.g.cs", source);
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});
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// Check whether [NotNullIfNotNull] is not available
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IncrementalValueProvider<bool> isNotNullIfNotNullAttributeNotAvailable =
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context.CompilationProvider
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.Select(static (item, _) => !item.HasAccessibleTypeWithMetadataName(NotNullIfNotNullAttributeMetadataName));
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// Generate the [NotNullIfNotNull] type
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context.RegisterConditionalSourceOutput(isNotNullIfNotNullAttributeNotAvailable, static context =>
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{
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string source = LoadAttributeSourceWithMetadataName(NotNullIfNotNullAttributeMetadataName);
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context.AddSource($"{NotNullIfNotNullAttributeMetadataName}.g.cs", source);
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});
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}
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/// <summary>
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/// Gets the generated source for a specified attribute.
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/// </summary>
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private static string LoadAttributeSourceWithMetadataName(string typeFullName)
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{
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string typeName = typeFullName.Split('.').Last();
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string filename = $"CommunityToolkit.Mvvm.SourceGenerators.EmbeddedResources.{typeName}.cs";
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Stream stream = Assembly.GetExecutingAssembly().GetManifestResourceStream(filename);
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StreamReader reader = new(stream);
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return reader.ReadToEnd();
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}
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}
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