refactor!: read generated resource defaults from declaration state

src/Beutl.Engine.SourceGenerators/AnalyzerReleases.Unshipped.md

@@ -4,3 +4,7 @@ Rule ID | Category | Severity | Notes
 --------|----------|----------|-------
 BESG001 | Beutl.Engine.SourceGenerators | Warning | EngineObjectResourceGenerator
 BESG002 | Beutl.Engine.SourceGenerators | Warning | FallbackTypeGenerator
+BESG003 | Beutl.Engine.SourceGenerators | Error | EngineObjectResourceGenerator
+BESG004 | Beutl.Engine.SourceGenerators | Error | EngineObjectResourceGenerator
+BESG005 | Beutl.Engine.SourceGenerators | Error | EngineObjectResourceGenerator
+BESG006 | Beutl.Engine.SourceGenerators | Error | EngineObjectResourceGenerator

src/Beutl.Engine.SourceGenerators/Diagnostics/DiagnosticDescriptors.cs

@@ -19,4 +19,36 @@ public static class DiagnosticDescriptors
         category: "Beutl.Engine.SourceGenerators",
         defaultSeverity: DiagnosticSeverity.Warning,
         isEnabledByDefault: true);
+
+    public static readonly DiagnosticDescriptor ResourcePropertyMissingInitializer = new(
+        id: "BESG003",
+        title: "Stable resource property declaration required",
+        messageFormat: "Property '{0}.{1}' must expose one stable declaration-time IProperty so detached Resource defaults can be generated; use a declaration initializer or a readonly computed backing field, do not replace it in a constructor, add a valid [ResourceDefaultValuesProvider] factory, or suppress Resource generation and implement Resource/ToResource manually",
+        category: "Beutl.Engine.SourceGenerators",
+        defaultSeverity: DiagnosticSeverity.Error,
+        isEnabledByDefault: true);
+
+    public static readonly DiagnosticDescriptor ResourcePrimaryConstructorNotSupported = new(
+        id: "BESG004",
+        title: "Primary constructor is incompatible with generated Resource defaults",
+        messageFormat: "Type '{0}' cannot use a primary constructor with initializer-only detached Resource defaults; add a valid [ResourceDefaultValuesProvider] factory, move to an ordinary constructor, or suppress Resource generation and implement Resource/ToResource manually",
+        category: "Beutl.Engine.SourceGenerators",
+        defaultSeverity: DiagnosticSeverity.Error,
+        isEnabledByDefault: true);
+
+    public static readonly DiagnosticDescriptor ResourceDefaultValuesProviderInvalid = new(
+        id: "BESG005",
+        title: "Resource defaults provider signature is invalid",
+        messageFormat: "Type '{0}' must declare exactly one [ResourceDefaultValuesProvider] method that is static, parameterless, non-generic, and returns '{0}'",
+        category: "Beutl.Engine.SourceGenerators",
+        defaultSeverity: DiagnosticSeverity.Error,
+        isEnabledByDefault: true);
+
+    public static readonly DiagnosticDescriptor ResourceDefaultValuesProviderRequiredOnDerivedType = new(
+        id: "BESG006",
+        title: "Derived resource defaults provider required",
+        messageFormat: "Type '{0}' derives from a type with an explicit resource defaults provider and must declare its own [ResourceDefaultValuesProvider] factory so inherited detached defaults are not evaluated through the initializer-only path",
+        category: "Beutl.Engine.SourceGenerators",
+        defaultSeverity: DiagnosticSeverity.Error,
+        isEnabledByDefault: true);
 }

src/Beutl.Engine.SourceGenerators/Emit/ResourceClassEmitter.cs

@@ -38,6 +38,7 @@ public static void Emit(StringBuilder sb, string indent, string currentTypeDispl
 
         string innerIndent = indent + "    ";
 
+        EmitConstructors(sb, innerIndent, currentTypeDisplay, info);
         EmitFields(sb, innerIndent, info);
         EmitProperties(sb, innerIndent, info);
         EmitGetOriginal(sb, innerIndent, currentTypeDisplay);
@@ -48,6 +49,83 @@ public static void Emit(StringBuilder sb, string indent, string currentTypeDispl
         sb.Append(indent).AppendLine("}");
     }
 
+    private static void EmitConstructors(
+        StringBuilder sb,
+        string innerIndent,
+        string currentTypeDisplay,
+        ClassInfo info)
+    {
+        if (!info.Symbol.IsAbstract)
+        {
+            sb.Append(innerIndent)
+                .Append("internal static Resource __CreateAttached")
+                .Append(info.Symbol.Name)
+                .AppendLine("()");
+            sb.Append(innerIndent).AppendLine("    => new(skipDefaultInitialization: true);");
+            sb.AppendLine();
+
+            sb.Append(innerIndent).AppendLine("public Resource()");
+            sb.Append(innerIndent)
+                .Append("    : this(")
+                .Append(currentTypeDisplay)
+                .AppendLine(".__CreateResourceDefaultValues())");
+            sb.Append(innerIndent).AppendLine("{");
+            sb.Append(innerIndent).AppendLine("}");
+            sb.AppendLine();
+        }
+
+        sb.Append(innerIndent)
+            .Append("protected Resource(")
+            .Append(currentTypeDisplay)
+            .AppendLine(" defaultValues)");
+        sb.Append(innerIndent).AppendLine("    : base(defaultValues)");
+        sb.Append(innerIndent).AppendLine("{");
+        foreach (ValuePropertyInfo property in info.ValueProperties)
+        {
+            if (property.ExcludeFromResource) continue;
+
+            string fieldName = EmitHelpers.ToFieldName(property.Name);
+            sb.Append(innerIndent)
+                .Append("    ")
+                .Append(fieldName)
+                .Append(" = defaultValues.")
+                .Append(property.Name)
+                .AppendLine(".DefaultValue;");
+        }
+        foreach (ObjectPropertyInfo property in info.ObjectProperties)
+        {
+            if (property.ExcludeFromResource) continue;
+
+            string fieldName = EmitHelpers.ToFieldName(property.Name);
+            string resourceType = EmitHelpers.GetResourceTypeName(property.ValueType);
+            string localName = fieldName + "DefaultValue";
+            sb.Append(innerIndent)
+                .Append("    if (defaultValues.")
+                .Append(property.Name)
+                .Append(".DefaultValue is { } ")
+                .Append(localName)
+                .AppendLine(")");
+            sb.Append(innerIndent).AppendLine("    {");
+            sb.Append(innerIndent)
+                .Append("        ")
+                .Append(fieldName)
+                .Append(" = (")
+                .Append(resourceType)
+                .Append(")")
+                .Append(localName)
+                .AppendLine(".ToResource(global::Beutl.Composition.CompositionContext.Default);");
+            sb.Append(innerIndent).AppendLine("    }");
+        }
+        sb.Append(innerIndent).AppendLine("}");
+        sb.AppendLine();
+
+        sb.Append(innerIndent).AppendLine("protected Resource(bool skipDefaultInitialization)");
+        sb.Append(innerIndent).AppendLine("    : base(skipDefaultInitialization)");
+        sb.Append(innerIndent).AppendLine("{");
+        sb.Append(innerIndent).AppendLine("}");
+        sb.AppendLine();
+    }
+
     private static void EmitFields(StringBuilder sb, string innerIndent, ClassInfo info)
     {
         foreach (ValuePropertyInfo property in info.ValueProperties)

src/Beutl.Engine.SourceGenerators/Emit/ResourceDefaultValuesEmitter.cs

@@ -0,0 +1,93 @@
+using System.Text;
+
+using Beutl.Engine.SourceGenerators.Models;
+
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+
+namespace Beutl.Engine.SourceGenerators.Emit;
+
+public static class ResourceDefaultValuesEmitter
+{
+    public static void Emit(
+        StringBuilder sb,
+        string indent,
+        string currentTypeDisplay,
+        ClassInfo info,
+        string? defaultsProviderMethod)
+    {
+        if (info.SuppressedResourceGeneration) return;
+
+        if (defaultsProviderMethod is not null)
+        {
+            EmitProviderFactory(sb, indent, currentTypeDisplay, defaultsProviderMethod);
+            return;
+        }
+
+        string constructorAccessibility = info.Symbol.IsSealed ? "private" : "protected";
+        string constructionType =
+            "global::Beutl.Engine.EngineObject.ResourceDefaultValuesConstruction";
+
+        IMethodSymbol? implicitParameterlessConstructor = info.Symbol.InstanceConstructors
+            .FirstOrDefault(static constructor =>
+                constructor.IsImplicitlyDeclared && constructor.Parameters.Length == 0);
+        if (implicitParameterlessConstructor is not null)
+        {
+            sb.Append(indent)
+                .Append(EmitHelpers.GetAccessibility(implicitParameterlessConstructor.DeclaredAccessibility))
+                .Append(' ')
+                .Append(info.Symbol.Name)
+                .AppendLine("()");
+            sb.Append(indent).AppendLine("{");
+            sb.Append(indent).AppendLine("}");
+            sb.AppendLine();
+        }
+
+        sb.Append(indent)
+            .AppendLine("[global::System.Diagnostics.CodeAnalysis.SetsRequiredMembers]");
+        sb.Append(indent)
+            .Append(constructorAccessibility)
+            .Append(' ')
+            .Append(info.Symbol.Name)
+            .Append('(')
+            .Append(constructionType)
+            .AppendLine(" construction)");
+        sb.Append(indent).AppendLine("    : base(construction)");
+        sb.Append(indent).AppendLine("{");
+        sb.Append(indent).AppendLine("}");
+
+        if (!info.Symbol.IsAbstract)
+        {
+            sb.AppendLine();
+            sb.Append(indent)
+                .Append("private static ")
+                .Append(currentTypeDisplay)
+                .AppendLine(" __CreateResourceDefaultValues()");
+            sb.Append(indent)
+                .Append("    => new(default(")
+                .Append(constructionType)
+                .AppendLine("));");
+        }
+    }
+
+    private static void EmitProviderFactory(
+        StringBuilder sb,
+        string indent,
+        string currentTypeDisplay,
+        string defaultsProviderMethod)
+    {
+        string escapedMethodName = SyntaxFacts.GetKeywordKind(defaultsProviderMethod) == SyntaxKind.None
+            ? defaultsProviderMethod
+            : "@" + defaultsProviderMethod;
+        sb.Append(indent)
+            .Append("private static ")
+            .Append(currentTypeDisplay)
+            .AppendLine(" __CreateResourceDefaultValues()");
+        sb.Append(indent)
+            .Append("    => ")
+            .Append(currentTypeDisplay)
+            .Append('.')
+            .Append(escapedMethodName)
+            .AppendLine("();");
+    }
+}

src/Beutl.Engine.SourceGenerators/Emit/ToResourceMethodEmitter.cs

@@ -20,7 +20,12 @@ public static void Emit(StringBuilder sb, string indent, string currentTypeDispl
         {
             sb.Append(indent).AppendLine($"public override {currentTypeDisplay}.Resource ToResource({renderContextType} context)");
             sb.Append(indent).AppendLine("{");
-            sb.Append(indent).AppendLine($"    var resource = new {currentTypeDisplay}.Resource();");
+            sb.Append(indent)
+                .Append("    var resource = ")
+                .Append(currentTypeDisplay)
+                .Append(".Resource.__CreateAttached")
+                .Append(info.Symbol.Name)
+                .AppendLine("();");
             sb.Append(indent).AppendLine("    bool updateOnly = true;");
             sb.Append(indent).AppendLine("    resource.Update(this, context, ref updateOnly);");
             sb.Append(indent).AppendLine($"    return resource;");