From 7556efdfdd286f385d7a12f03bdf18eef01bad41 Mon Sep 17 00:00:00 2001
From: Oliver Booth <me@olivr.me>
Date: Thu, 6 Apr 2023 17:00:39 +0100
Subject: [PATCH] chore: add AutoOverload and OverloadType attribute

---
 .../MethodOverloadGenerator.cs                | 22 ++++++++++
 .../SourceGenerator/OverloadSyntaxReceiver.cs | 41 +++++++++++++++++++
 .../AutoOverloadAttribute.cs                  |  6 +++
 .../OverloadTypeAttribute.cs                  | 20 +++++++++
 4 files changed, 89 insertions(+)
 create mode 100644 tools/SourceGenerator/MethodOverloadGenerator.cs
 create mode 100644 tools/SourceGenerator/OverloadSyntaxReceiver.cs
 create mode 100644 tools/X10D.MetaServices/AutoOverloadAttribute.cs
 create mode 100644 tools/X10D.MetaServices/OverloadTypeAttribute.cs

diff --git a/tools/SourceGenerator/MethodOverloadGenerator.cs b/tools/SourceGenerator/MethodOverloadGenerator.cs
new file mode 100644
index 0000000..cf05a35
--- /dev/null
+++ b/tools/SourceGenerator/MethodOverloadGenerator.cs
@@ -0,0 +1,22 @@
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+
+namespace SourceGenerator;
+
+[Generator]
+internal sealed class MethodOverloadGenerator : ISourceGenerator
+{
+    /// <inheritdoc />
+    public void Initialize(GeneratorInitializationContext context)
+    {
+        context.RegisterForSyntaxNotifications(() => new OverloadSyntaxReceiver());
+    }
+
+    /// <inheritdoc />
+    public void Execute(GeneratorExecutionContext context)
+    {
+        var syntaxReceiver = (OverloadSyntaxReceiver)context.SyntaxReceiver!;
+        IReadOnlyList<MethodDeclarationSyntax> candidateMethods = syntaxReceiver.CandidateMethods;
+        // TODO implement
+    }
+}
diff --git a/tools/SourceGenerator/OverloadSyntaxReceiver.cs b/tools/SourceGenerator/OverloadSyntaxReceiver.cs
new file mode 100644
index 0000000..cfe4668
--- /dev/null
+++ b/tools/SourceGenerator/OverloadSyntaxReceiver.cs
@@ -0,0 +1,41 @@
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using X10D.MetaServices;
+
+namespace SourceGenerator;
+
+public class OverloadSyntaxReceiver : ISyntaxReceiver
+{
+    private readonly List<MethodDeclarationSyntax> _candidateMethods = new();
+
+    public IReadOnlyList<MethodDeclarationSyntax> CandidateMethods
+    {
+        get => _candidateMethods.AsReadOnly();
+    }
+
+    public void OnVisitSyntaxNode(SyntaxNode syntaxNode)
+    {
+        if (syntaxNode is not MethodDeclarationSyntax methodDeclarationSyntax)
+        {
+            return;
+        }
+
+        if (methodDeclarationSyntax.AttributeLists.Count == 0)
+        {
+            return;
+        }
+
+        string attributeName = nameof(AutoOverloadAttribute).Replace("Attribute", string.Empty);
+        foreach (AttributeListSyntax attributeListSyntax in methodDeclarationSyntax.AttributeLists)
+        {
+            foreach (AttributeSyntax attributeSyntax in attributeListSyntax.Attributes)
+            {
+                if (attributeSyntax.Name.ToString() == attributeName)
+                {
+                    _candidateMethods.Add(methodDeclarationSyntax);
+                    break;
+                }
+            }
+        }
+    }
+}
diff --git a/tools/X10D.MetaServices/AutoOverloadAttribute.cs b/tools/X10D.MetaServices/AutoOverloadAttribute.cs
new file mode 100644
index 0000000..5630c84
--- /dev/null
+++ b/tools/X10D.MetaServices/AutoOverloadAttribute.cs
@@ -0,0 +1,6 @@
+namespace X10D.MetaServices;
+
+[AttributeUsage(AttributeTargets.Method, Inherited = false)]
+public sealed class AutoOverloadAttribute : Attribute
+{
+}
diff --git a/tools/X10D.MetaServices/OverloadTypeAttribute.cs b/tools/X10D.MetaServices/OverloadTypeAttribute.cs
new file mode 100644
index 0000000..d938a5b
--- /dev/null
+++ b/tools/X10D.MetaServices/OverloadTypeAttribute.cs
@@ -0,0 +1,20 @@
+namespace X10D.MetaServices;
+
+[AttributeUsage(AttributeTargets.Method | AttributeTargets.Parameter | AttributeTargets.ReturnValue, Inherited = false)]
+public sealed class OverloadTypeAttribute : Attribute
+{
+    /// <summary>
+    ///     Initializes a new instance of the <see cref="OverloadTypeAttribute"/> class.
+    /// </summary>
+    /// <param name="types">The types to overload.</param>
+    public OverloadTypeAttribute(params Type[] types)
+    {
+        Types = (Type[])types.Clone();
+    }
+
+    /// <summary>
+    ///     Gets an array of types to overload.
+    /// </summary>
+    /// <value>An array of types to overload.</value>
+    public Type[] Types { get; }
+}