Refactor 'asInternal' logic to remove duplicate attribute lookup

AutomaticInterface/AutomaticInterface/AutomaticInterfaceGenerator.cs

@@ -12,6 +12,7 @@ public class AutomaticInterfaceGenerator : IIncrementalGenerator
     public const string IgnoreAutomaticInterfaceAttributeName = "IgnoreAutomaticInterface";
     public const string NamespaceParameterName = "namespaceName";
     public const string InterfaceParameterName = "interfaceName";
+    public const string AsInternalParameterName = "asInternal";
 
     public void Initialize(IncrementalGeneratorInitializationContext context)
     {

AutomaticInterface/AutomaticInterface/Builder.cs

@@ -52,13 +52,12 @@ is not ClassDeclarationSyntax classSyntax
         {
             return string.Empty;
         }
-        var generationAttribute = GetGenerationAttribute(typeSymbol);
-        var asInternal = GetAsInternal(generationAttribute);
+
         var symbolDetails = GetSymbolDetails(typeSymbol, classSyntax);
         var interfaceGenerator = new InterfaceBuilder(
             symbolDetails.NamespaceName,
             symbolDetails.InterfaceName,
-            asInternal
+            symbolDetails.AccessLevel
         );
 
         interfaceGenerator.AddClassDocumentation(GetDocumentationForClass(classSyntax));
@@ -80,43 +79,6 @@ is not ClassDeclarationSyntax classSyntax
         return generatedCode;
     }
 
-    private static AttributeData? GetGenerationAttribute(ISymbol typeSymbol)
-    {
-        return typeSymbol
-            .GetAttributes()
-            .FirstOrDefault(x =>
-                x.AttributeClass != null
-                && x.AttributeClass.Name.Contains(AutomaticInterfaceGenerator.DefaultAttributeName)
-            );
-    }
-
-    private static string GetNameSpace(ISymbol typeSymbol, AttributeData? generationAttribute)
-    {
-        if (generationAttribute == null)
-        {
-            return typeSymbol.ContainingNamespace.ToDisplayString();
-        }
-
-        var customNs = generationAttribute.ConstructorArguments.FirstOrDefault().Value?.ToString();
-
-        return string.IsNullOrWhiteSpace(customNs)
-            ? typeSymbol.ContainingNamespace.ToDisplayString()
-            : customNs!;
-    }
-
-    private static bool GetAsInternal(AttributeData? generationAttribute)
-    {
-        if (generationAttribute == null)
-        {
-            return false;
-        }
-
-        var asInternal = (bool?)
-            generationAttribute.ConstructorArguments.Skip(2).FirstOrDefault().Value;
-
-        return asInternal.GetValueOrDefault();
-    }
-
     private static GeneratedSymbolDetails GetSymbolDetails(
         ITypeSymbol typeSymbol,
         ClassDeclarationSyntax classSyntax

AutomaticInterface/AutomaticInterface/GeneratedSymbolDetails.cs

@@ -34,11 +34,31 @@ ClassDeclarationSyntax classSyntax
             $"I{classSyntax.GetClassName()}"
         );
 
-    private static string PrepareValue(
-        AttributeData? generationAttribute,
-        string key,
-        string defaultValue
-    )
+    /// <summary>
+    /// Determines the access level for the generated interface.
+    /// This property is derived from the presence of <see cref="AutomaticInterfaceGenerator.AsInternalParameterName"/>
+    /// that, if set, defines the interface as `internal`. Otherwise, the interface defaults to `public`.
+    /// </summary>
+    public string AccessLevel { get; } =
+        PrepareValue(
+            generationAttribute,
+            AutomaticInterfaceGenerator.AsInternalParameterName,
+            false
+        )
+            ? "internal"
+            : "public";
+
+    /// <summary>
+    /// Prepares a value by retrieving it from an attribute's constructor arguments if available; otherwise, returns the provided default value.
+    /// </summary>
+    /// <typeparam name="T">The type of the value to prepare.</typeparam>
+    /// <param name="generationAttribute">The attribute data containing constructor arguments.</param>
+    /// <param name="key">The key to identify the relevant parameter in the constructor arguments.</param>
+    /// <param name="defaultValue">The default value to return if the attribute does not provide a value.</param>
+    /// <returns>
+    /// The retrieved value from the attribute constructor's arguments, or the provided default value if the key is not found.
+    /// </returns>
+    private static T PrepareValue<T>(AttributeData? generationAttribute, string key, T defaultValue)
     {
         var parameterSymbol = generationAttribute?.AttributeConstructor?.Parameters.SingleOrDefault(
             x => x.Name == key
@@ -49,10 +69,10 @@ string defaultValue
             var index = generationAttribute!.AttributeConstructor!.Parameters.IndexOf(
                 parameterSymbol
             );
-            var result = generationAttribute.ConstructorArguments[index].Value!.ToString();
-            if (!string.IsNullOrWhiteSpace(result))
+            var result = generationAttribute.ConstructorArguments[index].Value;
+            if (result != null)
             {
-                return result;
+                return (T)result;
             }
         }
 

AutomaticInterface/AutomaticInterface/InterfaceBuilder.cs

@@ -24,7 +24,7 @@ internal sealed record MethodInfo(
 
     public record EventInfo(string Name, string Type, string Documentation);
 
-    public class InterfaceBuilder(string nameSpaceName, string interfaceName, bool asInternal)
+    public class InterfaceBuilder(string nameSpaceName, string interfaceName, string accessLevel)
     {
         private const string Autogenerated = """
             //--------------------------------------------------------------------------------------------------
@@ -104,7 +104,7 @@ public string Build()
             cb.AppendLine(
                 "[global::System.CodeDom.Compiler.GeneratedCode(\"AutomaticInterface\", \"\")]"
             );
-            cb.AppendLine($"{(asInternal ? "internal" : "public")} partial interface {interfaceName}{genericType}");
+            cb.AppendLine($"{accessLevel} partial interface {interfaceName}{genericType}");
             cb.AppendLine("{");
 
             cb.Indent();

AutomaticInterface/AutomaticInterface/RegisterAttributesExtensions.cs

@@ -29,7 +29,7 @@ namespace AutomaticInterface
                         [AttributeUsage(AttributeTargets.Class)]
                         internal sealed class {{{AutomaticInterfaceGenerator.DefaultAttributeName}}}Attribute : Attribute
                         {
-                            internal {{{AutomaticInterfaceGenerator.DefaultAttributeName}}}Attribute(string {{{AutomaticInterfaceGenerator.NamespaceParameterName}}} = "", string {{{AutomaticInterfaceGenerator.InterfaceParameterName}}} = "", bool asInternal = false) { }
+                            internal {{{AutomaticInterfaceGenerator.DefaultAttributeName}}}Attribute(string? {{{AutomaticInterfaceGenerator.NamespaceParameterName}}} = default(string), string? {{{AutomaticInterfaceGenerator.InterfaceParameterName}}} = default(string), bool {{{AutomaticInterfaceGenerator.AsInternalParameterName}}} = false) { }
                         }
                     }
                     """,

AutomaticInterface/Tests/Misc/Misc.cs

@@ -366,8 +366,8 @@ class DemoClass
     }
 
     [Fact]
-    public async Task AsInternal()
-    {
+    public async Task AsInternal()
+    {
         const string code = """
 
             using AutomaticInterface;
@@ -381,13 +381,13 @@ public string AMethod(DemoClass? x, string y)
                 }
             }
 
-            """;
+            """;
         await Verify(Infrastructure.GenerateCode(code));
-    }
-
+    }
+
     [Fact]
-    public async Task AsInternalExplicitFalse()
-    {
+    public async Task AsInternalExplicitFalse()
+    {
         const string code = """
 
             using AutomaticInterface;
@@ -401,7 +401,7 @@ public string AMethod(DemoClass? x, string y)
                 }
             }
 
-            """;
+            """;
         await Verify(Infrastructure.GenerateCode(code));
     }
 }