From 0e56969bfb2537d4ca89810fde1ae75b9c494aca Mon Sep 17 00:00:00 2001
From: Jacob Marks <jacobjmarks@outlook.com>
Date: Wed, 24 Apr 2024 20:24:29 +1000
Subject: [PATCH] Use source generator

---
 .../RequestDelegateSourceGenerator.cs         | 36 +++++++++++++++++++
 .../Server.Core.SourceGenerators.csproj       | 19 ++++++++++
 Server.Core/QueryBindingEvaluator.cs          |  9 ++---
 Server.Core/Server.Core.csproj                |  4 +++
 dotnet-qs.sln                                 |  6 ++++
 5 files changed, 67 insertions(+), 7 deletions(-)
 create mode 100644 Server.Core.SourceGenerators/RequestDelegateSourceGenerator.cs
 create mode 100644 Server.Core.SourceGenerators/Server.Core.SourceGenerators.csproj

diff --git a/Server.Core.SourceGenerators/RequestDelegateSourceGenerator.cs b/Server.Core.SourceGenerators/RequestDelegateSourceGenerator.cs
new file mode 100644
index 0000000..1f417f5
--- /dev/null
+++ b/Server.Core.SourceGenerators/RequestDelegateSourceGenerator.cs
@@ -0,0 +1,36 @@
+using System.Text.Json;
+using System.Text.Json.Nodes;
+using Microsoft.CodeAnalysis;
+
+namespace Server.Core.SourceGenerators;
+
+[Generator(LanguageNames.CSharp)]
+public class RequestDelegateSourceGenerator : ISourceGenerator
+{
+    public void Initialize(GeneratorInitializationContext context)
+    {
+    }
+
+    public void Execute(GeneratorExecutionContext context)
+    {
+        static string indent(int depth = 1) => new(' ', 4 * depth);
+
+        context.AddSource($"Generated.RequestDelegates.g.cs",
+        $$"""
+        // <auto-generated/>
+        using Microsoft.AspNetCore.Http;
+        using Microsoft.AspNetCore.Mvc;
+
+        namespace {{context.Compilation.AssemblyName}};
+
+        public static partial class Generated
+        {
+            public static (string Route, Delegate Delegate)[] RequestDelegates =
+            [
+                {{string.Join("\n" + indent(2), Shared.Constants.Endpoints.Select(e =>
+                    $"(\"{e.Route}\", ([FromQuery] {e.Type} q, HttpResponse r) => r.WriteAsJsonAsync(q)),"))}}
+            ];
+        }
+        """);
+    }
+}
diff --git a/Server.Core.SourceGenerators/Server.Core.SourceGenerators.csproj b/Server.Core.SourceGenerators/Server.Core.SourceGenerators.csproj
new file mode 100644
index 0000000..87f3aeb
--- /dev/null
+++ b/Server.Core.SourceGenerators/Server.Core.SourceGenerators.csproj
@@ -0,0 +1,19 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <EnforceExtendedAnalyzerRules>true</EnforceExtendedAnalyzerRules>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.9.2" PrivateAssets="all" />
+    <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="3.3.4" PrivateAssets="all" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Shared\Shared.csproj" OutputItemType="Analyzer" />
+  </ItemGroup>
+
+</Project>
\ No newline at end of file
diff --git a/Server.Core/QueryBindingEvaluator.cs b/Server.Core/QueryBindingEvaluator.cs
index 1108636..f2fff72 100644
--- a/Server.Core/QueryBindingEvaluator.cs
+++ b/Server.Core/QueryBindingEvaluator.cs
@@ -13,11 +13,6 @@ namespace Server.Core;
 
 public class QueryBindingEvaluator : IDisposable
 {
-    private static Delegate CreateEndpointDelegate<T>() => ([FromQuery] T q, HttpResponse r) => r.WriteAsJsonAsync(q);
-    private static readonly MethodInfo createEndpointDelegateMethod = typeof(QueryBindingEvaluator)
-        .GetMethod(nameof(CreateEndpointDelegate), 1, BindingFlags.NonPublic | BindingFlags.Static, null, [], null)
-            ?? throw new InvalidOperationException($"Could not find {nameof(CreateEndpointDelegate)} method.");
-
     private readonly TestServer _minimalApiTestServer;
     private readonly HttpClient _minimalApiTestServerClient;
 
@@ -46,8 +41,8 @@ private static TestServer CreateMinimalApiTestServer()
             app.UseRouting();
             app.UseEndpoints(endpoints =>
             {
-                foreach (var endpoint in Constants.Endpoints)
-                    endpoints.MapGet(endpoint.Route, (Delegate)createEndpointDelegateMethod.MakeGenericMethod(endpoint.ParamType).Invoke(null, null)!);
+                foreach (var (route, @delegate) in Generated.RequestDelegates)
+                    endpoints.MapGet(route, @delegate);
             });
         });
 
diff --git a/Server.Core/Server.Core.csproj b/Server.Core/Server.Core.csproj
index dcf27e4..ac5b127 100644
--- a/Server.Core/Server.Core.csproj
+++ b/Server.Core/Server.Core.csproj
@@ -4,6 +4,7 @@
     <TargetFramework>net8.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
+    <EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles>
   </PropertyGroup>
 
   <ItemGroup>
@@ -16,6 +17,9 @@
 
   <ItemGroup>
     <ProjectReference Include="..\Shared\Shared.csproj" />
+    <ProjectReference Include="..\Server.Core.SourceGenerators\Server.Core.SourceGenerators.csproj"
+      OutputItemType="Analyzer"
+      ReferenceOutputAssembly="false" />
   </ItemGroup>
 
 </Project>
\ No newline at end of file
diff --git a/dotnet-qs.sln b/dotnet-qs.sln
index 90e8481..f1fbc57 100644
--- a/dotnet-qs.sln
+++ b/dotnet-qs.sln
@@ -13,6 +13,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Shared", "Shared\Shared.csp
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Server.Core.Tests", "Server.Core.Tests\Server.Core.Tests.csproj", "{5A856409-9FA3-4C23-B65B-3BCA7275EBC1}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Server.Core.SourceGenerators", "Server.Core.SourceGenerators\Server.Core.SourceGenerators.csproj", "{2B7D08BF-781C-421B-9C9A-E5B03F606A1A}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -42,5 +44,9 @@ Global
 		{5A856409-9FA3-4C23-B65B-3BCA7275EBC1}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{5A856409-9FA3-4C23-B65B-3BCA7275EBC1}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{5A856409-9FA3-4C23-B65B-3BCA7275EBC1}.Release|Any CPU.Build.0 = Release|Any CPU
+		{2B7D08BF-781C-421B-9C9A-E5B03F606A1A}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{2B7D08BF-781C-421B-9C9A-E5B03F606A1A}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{2B7D08BF-781C-421B-9C9A-E5B03F606A1A}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{2B7D08BF-781C-421B-9C9A-E5B03F606A1A}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 EndGlobal