Add incremental INotifyPropertyChangedGenerator

Author: Sergio0694

CommunityToolkit.Mvvm.SourceGenerators/ComponentModel/INotifyPropertyChangedGenerator.Incremental.cs

@@ -0,0 +1,78 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Collections.Immutable;
+using System.Linq;
+using CommunityToolkit.Mvvm.SourceGenerators.Diagnostics;
+using CommunityToolkit.Mvvm.SourceGenerators.Extensions;
+using CommunityToolkit.Mvvm.SourceGenerators.Input.Models;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using static CommunityToolkit.Mvvm.SourceGenerators.Diagnostics.DiagnosticDescriptors;
+
+namespace CommunityToolkit.Mvvm.SourceGenerators;
+
+/// <summary>
+/// A source generator for the <c>INotifyPropertyChangedAttribute</c> type.
+/// </summary>
+[Generator(LanguageNames.CSharp)]
+public sealed class INotifyPropertyChangedGenerator2 : TransitiveMembersGenerator2<INotifyPropertyChangedInfo>
+{
+    /// <summary>
+    /// Initializes a new instance of the <see cref="INotifyPropertyChangedGenerator2"/> class.
+    /// </summary>
+    public INotifyPropertyChangedGenerator2()
+        : base("global::CommunityToolkit.Mvvm.ComponentModel.INotifyPropertyChangedAttribute")
+    {
+    }
+
+    /// <inheritdoc/>
+    protected override INotifyPropertyChangedInfo GetInfo(AttributeData attributeData)
+    {
+        if (attributeData.TryGetNamedArgument("IncludeAdditionalHelperMethods", out bool includeAdditionalHelperMethods))
+        {
+            return new(includeAdditionalHelperMethods);
+        }
+
+        return new(false);
+    }
+
+    /// <inheritdoc/>
+    protected override bool ValidateTargetType(
+        INamedTypeSymbol typeSymbol,
+        INotifyPropertyChangedInfo info,
+        out ImmutableArray<Diagnostic> diagnostics)
+    {
+        ImmutableArray<Diagnostic>.Builder builder = ImmutableArray.CreateBuilder<Diagnostic>();
+
+        // Check if the type already implements INotifyPropertyChanged
+        if (typeSymbol.AllInterfaces.Any(i => i.HasFullyQualifiedName("global::System.ComponentModel.INotifyPropertyChanged")))
+        {
+            builder.Add(DuplicateINotifyPropertyChangedInterfaceForINotifyPropertyChangedAttributeError, typeSymbol, typeSymbol);
+
+            diagnostics = builder.ToImmutable();
+
+            return false;
+        }
+
+        diagnostics = builder.ToImmutable();
+
+        return true;
+    }
+
+    /// <inheritdoc/>
+    protected override ImmutableArray<MemberDeclarationSyntax> FilterDeclaredMembers(INotifyPropertyChangedInfo info, ClassDeclarationSyntax classDeclaration)
+    {
+        // If requested, only include the event and the basic methods to raise it, but not the additional helpers
+        if (!info.IncludeAdditionalHelperMethods)
+        {
+            return classDeclaration.Members.Where(
+                static member => member
+                    is EventFieldDeclarationSyntax
+                    or MethodDeclarationSyntax { Identifier.ValueText: "OnPropertyChanged" }).ToImmutableArray();
+        }
+
+        return classDeclaration.Members.ToImmutableArray();
+    }
+}

CommunityToolkit.Mvvm.SourceGenerators/ComponentModel/Models/INotifyPropertyChangedInfo.cs

@@ -0,0 +1,11 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace CommunityToolkit.Mvvm.SourceGenerators.Input.Models;
+
+/// <summary>
+/// A model with gathered info on a given <c>INotifyPropertyChangedAttribute</c> instance.
+/// </summary>
+/// <param name="IncludeAdditionalHelperMethods">Whether to also generate helper methods in the target type.</param>
+public sealed record INotifyPropertyChangedInfo(bool IncludeAdditionalHelperMethods);

CommunityToolkit.Mvvm.SourceGenerators/ComponentModel/TransitiveMembersGenerator.Incremental.cs

@@ -48,10 +48,10 @@ public abstract partial class TransitiveMembersGenerator2<TInfo> : IIncrementalG
     /// </summary>
     /// <param name="attributeType">The fully qualified name of the attribute type to look for.</param>
     /// <param name="comparer">An <see cref="IEqualityComparer{T}"/> instance to compare intermediate models.</param>
-    protected TransitiveMembersGenerator2(string attributeType, IEqualityComparer<TInfo> comparer)
+    private protected TransitiveMembersGenerator2(string attributeType, IEqualityComparer<TInfo>? comparer = null)
     {
         this.attributeType = attributeType;
-        this.comparer = comparer;
+        this.comparer = comparer ?? EqualityComparer<TInfo>.Default;
 
         string attributeTypeName = attributeType.Split('.').Last();
         string filename = $"CommunityToolkit.Mvvm.SourceGenerators.EmbeddedResources.{attributeTypeName.Replace("Attribute", string.Empty)}.cs";