[Binding SG] Split bindings source generated code into multiple files

src/Controls/src/BindingSourceGen/BindingCodeWriter.cs

@@ -3,21 +3,11 @@
 
 namespace Microsoft.Maui.Controls.BindingSourceGen;
 
-public sealed class BindingCodeWriter
+public static class BindingCodeWriter
 {
 	public static string GeneratedCodeAttribute => $"[GeneratedCodeAttribute(\"{typeof(BindingCodeWriter).Assembly.FullName}\", \"{typeof(BindingCodeWriter).Assembly.GetName().Version}\")]";
 
-	public string GenerateCode()
-	{
-		if (_bindings.Count == 0)
-		{
-			return string.Empty;
-		}
-
-		return DoGenerateCode();
-	}
-
-	private string DoGenerateCode() => $$"""
+	public static string GenerateCommonCode() => $$"""
 		//------------------------------------------------------------------------------
 		// <auto-generated>
 		//     This code was generated by a .NET MAUI source generator.
@@ -35,7 +25,7 @@ namespace System.Runtime.CompilerServices
 
 			{{GeneratedCodeAttribute}}
 			[AttributeUsage(AttributeTargets.Method, AllowMultiple = true)]
-			file sealed class InterceptsLocationAttribute : Attribute
+			internal sealed class InterceptsLocationAttribute : Attribute
 			{
 				public InterceptsLocationAttribute(string filePath, int line, int column)
 				{
@@ -52,16 +42,11 @@ public InterceptsLocationAttribute(string filePath, int line, int column)
 
 		namespace Microsoft.Maui.Controls.Generated
 		{
-			using System;
 			using System.CodeDom.Compiler;
-			using System.Runtime.CompilerServices;
-			using Microsoft.Maui.Controls.Internals;
 
 			{{GeneratedCodeAttribute}}
-			file static class GeneratedBindableObjectExtensions
+			internal static partial class GeneratedBindableObjectExtensions
 			{
-				{{GenerateBindingMethods(indent: 2)}}
-
 				private static bool ShouldUseSetter(BindingMode mode, BindableProperty bindableProperty)
 					=> mode == BindingMode.OneWayToSource
 						|| mode == BindingMode.TwoWay
@@ -72,27 +57,48 @@ private static bool ShouldUseSetter(BindingMode mode, BindableProperty bindableP
 		}
 		""";
 
-	private readonly List<SetBindingInvocationDescription> _bindings = new();
+	private static string GenerateBindingCode(string bindingMethodBody) => $$"""
+		//------------------------------------------------------------------------------
+		// <auto-generated>
+		//     This code was generated by a .NET MAUI source generator.
+		//
+		//     Changes to this file may cause incorrect behavior and will be lost if
+		//     the code is regenerated.
+		// </auto-generated>
+		//------------------------------------------------------------------------------
+		#nullable enable
 
-	public void AddBinding(SetBindingInvocationDescription binding)
+		namespace Microsoft.Maui.Controls.Generated
+		{
+			using System;
+			using System.CodeDom.Compiler;
+			using System.Runtime.CompilerServices;
+			using Microsoft.Maui.Controls.Internals;
+
+			internal static partial class GeneratedBindableObjectExtensions
+			{
+				{{bindingMethodBody}}
+			}
+		}
+	""";
+
+
+	public static string GenerateBinding(SetBindingInvocationDescription binding, uint id)
 	{
 		if (!binding.NullableContextEnabled)
 		{
 			var referenceTypesConditionalAccessTransformer = new ReferenceTypesConditionalAccessTransformer();
 			binding = referenceTypesConditionalAccessTransformer.Transform(binding);
 		}
-		_bindings.Add(binding);
+
+		var bindingMethod = GenerateBindingMethod(binding, id);
+		return GenerateBindingCode(bindingMethod);
 	}
 
-	private string GenerateBindingMethods(int indent)
+	private static string GenerateBindingMethod(SetBindingInvocationDescription binding, uint id)
 	{
-		using var builder = new BindingInterceptorCodeBuilder(indent);
-
-		for (int i = 0; i < _bindings.Count; i++)
-		{
-			builder.AppendSetBindingInterceptor(id: i + 1, _bindings[i]);
-		}
-
+		using var builder = new BindingInterceptorCodeBuilder(indent: 2);
+		builder.AppendSetBindingInterceptor(id: id, binding: binding);
 		return builder.ToString();
 	}
 
@@ -113,10 +119,8 @@ public BindingInterceptorCodeBuilder(int indent = 0)
 			_indentedTextWriter = new IndentedTextWriter(_stringWriter, "\t") { Indent = indent };
 		}
 
-		public void AppendSetBindingInterceptor(int id, SetBindingInvocationDescription binding)
+		public void AppendSetBindingInterceptor(uint id, SetBindingInvocationDescription binding)
 		{
-			AppendBlankLine();
-
 			AppendLine(GeneratedCodeAttribute);
 			AppendInterceptorAttribute(binding.Location);
 			Append($"public static void SetBinding{id}");

src/Controls/src/BindingSourceGen/BindingSourceGenerator.cs

@@ -15,7 +15,6 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
 		)
 		.WithTrackingName(TrackingNames.BindingsWithDiagnostics);
 
-
 		context.RegisterSourceOutput(bindingsWithDiagnostics, (spc, bindingWithDiagnostic) =>
 		{
 			foreach (var diagnostic in bindingWithDiagnostic.Diagnostics)
@@ -27,20 +26,19 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
 		var bindings = bindingsWithDiagnostics
 			.Where(static binding => !binding.HasDiagnostics)
 			.Select(static (binding, t) => binding.Value)
-			.WithTrackingName(TrackingNames.Bindings)
-			.Collect();
-
+			.WithTrackingName(TrackingNames.Bindings);
 
-		context.RegisterSourceOutput(bindings, (spc, bindings) =>
+		context.RegisterPostInitializationOutput(spc =>
 		{
-			var codeWriter = new BindingCodeWriter();
-
-			foreach (var binding in bindings)
-			{
-				codeWriter.AddBinding(binding);
-			}
+			spc.AddSource("GeneratedBindableObjectExtensionsCommon.g.cs", BindingCodeWriter.GenerateCommonCode());
+		});
 
-			spc.AddSource("GeneratedBindableObjectExtensions.g.cs", codeWriter.GenerateCode());
+		context.RegisterImplementationSourceOutput(bindings, (spc, binding) =>
+		{
+			var fileName = $"{binding.Location.FilePath}-GeneratedBindableObjectExtensions-{binding.Location.Line}-{binding.Location.Column}.g.cs";
+			var sanitizedFileName = fileName.Replace('/', '-').Replace('\\', '-').Replace(':', '-');
+			var code = BindingCodeWriter.GenerateBinding(binding, (uint)Math.Abs(binding.Location.GetHashCode()));
+			spc.AddSource(sanitizedFileName, code);
 		});
 	}
 

src/Controls/src/BindingSourceGen/BindingSourceGeneratorUtilities.cs

@@ -2,7 +2,7 @@
 
 namespace Microsoft.Maui.Controls.BindingSourceGen;
 
-internal static class BindingGenerationUtilities
+public static class BindingGenerationUtilities
 {
     internal static bool IsTypeNullable(ITypeSymbol typeInfo, bool enabledNullable)
     {

src/Controls/src/BindingSourceGen/GeneratorDataModels.cs

@@ -100,7 +100,7 @@ public interface IPathPart : IEquatable<IPathPart>
 	public string? PropertyName { get; }
 }
 
-internal sealed record Result<T>(T? OptionalValue, EquatableArray<DiagnosticInfo> Diagnostics)
+public sealed record Result<T>(T? OptionalValue, EquatableArray<DiagnosticInfo> Diagnostics)
 {
 	public bool HasDiagnostics => Diagnostics.Length > 0;
 

src/Controls/tests/BindingSourceGen.UnitTests/AssertExtensions.cs

@@ -16,6 +16,8 @@ internal static void CodeIsEqual(string expectedCode, string actualCode)
         {
             Assert.Equal(expectedLine, actualLine);
         }
+
+        Assert.Equal(expectedLines.Count(), actualLines.Count());
     }
 
     internal static void BindingsAreEqual(SetBindingInvocationDescription expectedBinding, CodeGeneratorResult codeGeneratorResult)

src/Controls/tests/BindingSourceGen.UnitTests/BindingCodeWriterTests.cs

@@ -7,22 +7,9 @@ namespace BindingSourceGen.UnitTests;
 public class BindingCodeWriterTests
 {
     [Fact]
-    public void BuildsWholeDocument()
+    public void BuildsCommonCode()
     {
-        var codeWriter = new BindingCodeWriter();
-        codeWriter.AddBinding(new SetBindingInvocationDescription(
-            Location: new InterceptorLocation(FilePath: @"Path\To\Program.cs", Line: 20, Column: 30),
-            SourceType: new TypeDescription("global::MyNamespace.MySourceClass", IsValueType: false, IsNullable: false, IsGenericParameter: false),
-            PropertyType: new TypeDescription("global::MyNamespace.MyPropertyClass", IsValueType: false, IsNullable: false, IsGenericParameter: false),
-            Path: new EquatableArray<IPathPart>([
-                new MemberAccess("A"),
-                new ConditionalAccess(new MemberAccess("B")),
-                new ConditionalAccess(new MemberAccess("C")),
-            ]),
-            SetterOptions: new(IsWritable: true, AcceptsNullValue: false),
-            NullableContextEnabled: true));
-
-        var code = codeWriter.GenerateCode();
+        var code = BindingCodeWriter.GenerateCommonCode();
         AssertExtensions.CodeIsEqual(
             $$"""
             //------------------------------------------------------------------------------
@@ -42,30 +29,75 @@ namespace System.Runtime.CompilerServices
 
                 {{BindingCodeWriter.GeneratedCodeAttribute}}
                 [AttributeUsage(AttributeTargets.Method, AllowMultiple = true)]
-                file sealed class InterceptsLocationAttribute : Attribute
+                internal sealed class InterceptsLocationAttribute : Attribute
                 {
                     public InterceptsLocationAttribute(string filePath, int line, int column)
                     {
                         FilePath = filePath;
                         Line = line;
                         Column = column;
                     }
-            
+
                     public string FilePath { get; }
                     public int Line { get; }
                     public int Column { get; }
                 }
             }
 
+            namespace Microsoft.Maui.Controls.Generated
+            {
+                using System.CodeDom.Compiler;
+
+                {{BindingCodeWriter.GeneratedCodeAttribute}}
+                internal static partial class GeneratedBindableObjectExtensions
+                {
+                    private static bool ShouldUseSetter(BindingMode mode, BindableProperty bindableProperty)
+                        => mode == BindingMode.OneWayToSource
+                            || mode == BindingMode.TwoWay
+                            || (mode == BindingMode.Default
+                                && (bindableProperty.DefaultBindingMode == BindingMode.OneWayToSource
+                                    || bindableProperty.DefaultBindingMode == BindingMode.TwoWay));
+                }
+            }
+            """,
+            code);
+    }
+
+    [Fact]
+    public void BuildsWholeBinding()
+    {
+        var code = BindingCodeWriter.GenerateBinding(new SetBindingInvocationDescription(
+            Location: new InterceptorLocation(FilePath: @"Path\To\Program.cs", Line: 20, Column: 30),
+            SourceType: new TypeDescription("global::MyNamespace.MySourceClass", IsValueType: false, IsNullable: false, IsGenericParameter: false),
+            PropertyType: new TypeDescription("global::MyNamespace.MyPropertyClass", IsValueType: false, IsNullable: false, IsGenericParameter: false),
+            Path: new EquatableArray<IPathPart>([
+                new MemberAccess("A"),
+                new ConditionalAccess(new MemberAccess("B")),
+                new ConditionalAccess(new MemberAccess("C")),
+            ]),
+            SetterOptions: new(IsWritable: true, AcceptsNullValue: false),
+            NullableContextEnabled: true), id: 1);
+
+        AssertExtensions.CodeIsEqual(
+            $$"""
+            //------------------------------------------------------------------------------
+            // <auto-generated>
+            //     This code was generated by a .NET MAUI source generator.
+            //
+            //     Changes to this file may cause incorrect behavior and will be lost if
+            //     the code is regenerated.
+            // </auto-generated>
+            //------------------------------------------------------------------------------
+            #nullable enable
+
             namespace Microsoft.Maui.Controls.Generated
             {
                 using System;
                 using System.CodeDom.Compiler;
                 using System.Runtime.CompilerServices;
                 using Microsoft.Maui.Controls.Internals;
 
-                {{BindingCodeWriter.GeneratedCodeAttribute}}
-                file static class GeneratedBindableObjectExtensions
+                internal static partial class GeneratedBindableObjectExtensions
                 {
 
                     {{BindingCodeWriter.GeneratedCodeAttribute}}
@@ -115,13 +147,6 @@ public static void SetBinding1(
                         };
                         bindableObject.SetBinding(bindableProperty, binding);
                     }
-
-                    private static bool ShouldUseSetter(BindingMode mode, BindableProperty bindableProperty)
-                        => mode == BindingMode.OneWayToSource
-                            || mode == BindingMode.TwoWay
-                            || (mode == BindingMode.Default
-                                && (bindableProperty.DefaultBindingMode == BindingMode.OneWayToSource
-                                    || bindableProperty.DefaultBindingMode == BindingMode.TwoWay));
                 }
             }
             """,
@@ -482,5 +507,4 @@ public static void SetBinding1(
             """,
             code);
     }
-
 }