feature: introduce source generator for enum code generation

Directory.Packages.props

@@ -10,7 +10,9 @@
     <PackageVersion Include="Newtonsoft.Json" Version="13.0.3" />
     <PackageVersion Include="NUnit" Version="3.13.3" />
     <PackageVersion Include="NUnit3TestAdapter" Version="4.5.0" />
-    <PackageVersion Include="Microsoft.CodeAnalysis" Version="4.9.2" />
+    <PackageVersion Include="Microsoft.CodeAnalysis" Version="4.10.0" />
+    <PackageVersion Include="Microsoft.CodeAnalysis.Analyzers" Version="3.3.4" />
+    <PackageVersion Include="Microsoft.CodeAnalysis.CSharp" Version="4.10.0" />
     <PackageVersion Include="Microsoft.SourceLink.GitHub" Version="8.0.0" />
     <PackageVersion Include="Microsoft.Extensions.Logging" Version="8.0.0" />
     <PackageVersion Include="Microsoft.Extensions.Logging.Configuration" Version="8.0.0" />
@@ -23,5 +25,6 @@
     <PackageVersion Include="StackExchange.Redis" Version="2.7.33" />
     <PackageVersion Include="System.IdentityModel.Tokens.Jwt" Version="7.5.1" />
     <PackageVersion Include="System.Interactive.Async" Version="6.0.1" />
+
   </ItemGroup>
 </Project>

Garnet.sln

@@ -1,4 +1,4 @@
-Microsoft Visual Studio Solution File, Format Version 12.00
+Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio Version 17
 VisualStudioVersion = 17.0.31808.319
 MinimumVisualStudioVersion = 10.0.40219.1
@@ -96,6 +96,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "CommandInfoUpdater", "playg
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "SampleModule", "playground\SampleModule\SampleModule.csproj", "{A8CA619E-8F13-4EF8-943F-2D5E3FEBFB3F}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Garnet.gen", "libs\gen\Garnet.gen.csproj", "{E248012E-1D19-4114-924F-EFC9E859C4CD}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -280,6 +282,14 @@ Global
 		{A8CA619E-8F13-4EF8-943F-2D5E3FEBFB3F}.Release|Any CPU.Build.0 = Release|Any CPU
 		{A8CA619E-8F13-4EF8-943F-2D5E3FEBFB3F}.Release|x64.ActiveCfg = Release|Any CPU
 		{A8CA619E-8F13-4EF8-943F-2D5E3FEBFB3F}.Release|x64.Build.0 = Release|Any CPU
+		{E248012E-1D19-4114-924F-EFC9E859C4CD}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{E248012E-1D19-4114-924F-EFC9E859C4CD}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{E248012E-1D19-4114-924F-EFC9E859C4CD}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{E248012E-1D19-4114-924F-EFC9E859C4CD}.Debug|x64.Build.0 = Debug|Any CPU
+		{E248012E-1D19-4114-924F-EFC9E859C4CD}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{E248012E-1D19-4114-924F-EFC9E859C4CD}.Release|Any CPU.Build.0 = Release|Any CPU
+		{E248012E-1D19-4114-924F-EFC9E859C4CD}.Release|x64.ActiveCfg = Release|Any CPU
+		{E248012E-1D19-4114-924F-EFC9E859C4CD}.Release|x64.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -309,6 +319,7 @@ Global
 		{9F6E4734-6341-4A9C-A7FF-636A39D8BEAD} = {346A5A53-51E4-4A75-B7E6-491D950382CE}
 		{9BE474A2-1547-43AC-B4F2-FB48A01FA995} = {69A71E2C-00E3-42F3-854E-BE157A24834E}
 		{A8CA619E-8F13-4EF8-943F-2D5E3FEBFB3F} = {69A71E2C-00E3-42F3-854E-BE157A24834E}
+		{E248012E-1D19-4114-924F-EFC9E859C4CD} = {147FCE31-EC09-4C90-8E4D-37CA87ED18C3}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {2C02C405-4798-41CA-AF98-61EDFEF6772E}

libs/common/GenerateEnumUtilsAttribute.cs

@@ -0,0 +1,12 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+
+using System;
+
+namespace Garnet.common
+{
+    [AttributeUsage(AttributeTargets.Enum)]
+    public sealed class GenerateEnumDescriptionUtilsAttribute : Attribute
+    {
+    }
+}

libs/gen/EnumsSourceGenerator.cs

@@ -0,0 +1,169 @@
+using System.Text;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+
+namespace Garnet;
+
+[Generator]
+public class EnumsSourceGenerator : ISourceGenerator
+{
+    const string GeneratedClassName = "EnumUtils";
+    public void Initialize(GeneratorInitializationContext context)
+    {
+        context.RegisterForSyntaxNotifications(() => new EnumsSyntaxReceiver());
+    }
+
+    public void Execute(GeneratorExecutionContext context)
+    {
+        var syntaxReceiver = context.SyntaxReceiver as EnumsSyntaxReceiver;
+        if (syntaxReceiver is null) return;
+
+        foreach (var enumDeclaration in syntaxReceiver.Enums)
+        {
+            var namespaceDeclaration = enumDeclaration.FirstAncestorOrSelf<NamespaceDeclarationSyntax>();
+            var enumName = enumDeclaration.Identifier.Text;
+
+            var semanticModel = context.Compilation.GetSemanticModel(enumDeclaration.SyntaxTree);
+
+            var values = enumDeclaration.Members
+                .Select(m => (
+                    m.Identifier.Text,
+                    semanticModel.GetOperation(m.EqualsValue?.Value)!.ConstantValue.Value,
+                    Description: m.AttributeLists
+                        .SelectMany(al => al.Attributes).Where(a => a.Name.ToString() == "Description")
+                        .SingleOrDefault()
+                ))
+                .ToList();
+
+            var classBuilder = new StringBuilder();
+            classBuilder.AppendLine("// <auto-generated>");
+            classBuilder.AppendLine($"// This code was generated by the {nameof(EnumsSourceGenerator)} source generator.");
+            classBuilder.AppendLine("// </auto-generated>");
+
+            classBuilder.AppendLine("using System;");
+            classBuilder.AppendLine("using System.ComponentModel;");
+            classBuilder.AppendLine("using System.Numerics;");
+            classBuilder.AppendLine($"using {namespaceDeclaration!.Name};");
+            classBuilder.AppendLine();
+            classBuilder.AppendLine("namespace Garnet.common;");
+            classBuilder.AppendLine();
+            classBuilder.AppendLine("/// <summary>");
+            classBuilder.AppendLine($"/// Utility methods for enums.");
+            classBuilder.AppendLine("/// </summary>");
+            classBuilder.AppendLine($"public static partial class {GeneratedClassName}");
+            classBuilder.AppendLine("{");
+            classBuilder.AppendLine(GenerateTryParseEnumFromDescriptionMethod(enumName, values));
+            classBuilder.AppendLine();
+            classBuilder.AppendLine(GenerateGetEnumDescriptionsMethod(enumName, values));
+            classBuilder.AppendLine("}");
+            var classSource = classBuilder.ToString();
+            context.AddSource($"{GeneratedClassName}.{enumName}.g.cs", classSource);
+        }
+    }
+
+    private static string GenerateTryParseEnumFromDescriptionMethod(string enumName, List<(string Name, object? Value, AttributeSyntax Description)> values)
+    {
+        var method = new StringBuilder();
+        method.AppendLine($"    /// <summary>");
+        method.AppendLine($"    /// Tries to parse the enum value from the description.");
+        method.AppendLine($"    /// </summary>");
+        method.AppendLine($"    /// <param name=\"description\">Enum description.</param>");
+        method.AppendLine($"    /// <param name=\"result\">Enum value.</param>");
+        method.AppendLine($"    /// <returns>True if successful.</returns>");
+        method.AppendLine($"    public static bool TryParse{enumName}FromDescription(string description, out {enumName} result)");
+        method.AppendLine("    {");
+        method.AppendLine("        result = default;");
+        method.AppendLine("        switch (description)");
+        method.AppendLine("        {");
+        foreach (var (name, _, description) in values)
+        {
+            bool hasDescription = false;
+            var descriptionValue = description?.ArgumentList?.Arguments.FirstOrDefault()?.ToString();
+            if (descriptionValue is not null)
+            {
+                hasDescription = true;
+                method.AppendLine($"            case {descriptionValue}:");
+            }
+
+            if (!hasDescription) continue;
+            method.AppendLine($"                result = {enumName}.{name};");
+            method.AppendLine("                return true;");
+        }
+        method.AppendLine("        }");
+        method.AppendLine();
+        method.AppendLine("        return false;");
+        method.AppendLine("    }");
+        method.AppendLine();
+
+        return method.ToString();
+    }
+
+    private static string GenerateGetEnumDescriptionsMethod(string enumName, List<(string Name, object? Value, AttributeSyntax Description)> values)
+    {
+        var method = new StringBuilder();
+        method.AppendLine($"    /// <summary>");
+        method.AppendLine($"    /// Gets the descriptions of the set flags. Assumes the enum is a flags enum.");
+        method.AppendLine($"    /// If no description exists, returns the ToString() value of the input value.");
+        method.AppendLine($"    /// </summary>");
+        method.AppendLine($"    /// <param name=\"value\">Enum value.</param>");
+        method.AppendLine($"    /// <returns>Array of descriptions.</returns>");
+        method.AppendLine($"    public static string[] Get{enumName}Descriptions({enumName} value)");
+        method.AppendLine("    {");
+        foreach (var (name, value, description) in values)
+        {
+            if (!IsPow2(value))
+            {
+                var toString = description?.ArgumentList?.Arguments.FirstOrDefault()?.ToString() ?? $"\"{name}\"";
+                method.AppendLine($"        if (value is {enumName}.{name}) return [{toString}];");
+            }
+        }
+        method.AppendLine("        var setFlags = BitOperations.PopCount((ulong)value);");
+        method.AppendLine("        if (setFlags == 1)");
+        method.AppendLine("        {");
+        method.AppendLine("            return value switch");
+        method.AppendLine("            {");
+        foreach (var (name, value, description) in values)
+        {
+            if (description is null) continue;
+            if (!IsPow2(value)) continue;
+            method.AppendLine($"                {enumName}.{name} => [{description?.ArgumentList?.Arguments.FirstOrDefault()?.ToString()}],");
+        }
+        method.AppendLine($"                _ => [value.ToString()],");
+        method.AppendLine("            };");
+        method.AppendLine("        }");
+        method.AppendLine();
+        method.AppendLine("        var descriptions = new string[setFlags];");
+        method.AppendLine("        var index = 0;");
+        foreach (var (name, value, description) in values)
+        {
+            if (description is null) continue;
+            if (!IsPow2(value)) continue;
+            method.AppendLine($"        if ((value & {enumName}.{name}) != 0) descriptions[index++] = {description.ArgumentList?.Arguments.FirstOrDefault()?.ToString()};");
+        }
+        method.AppendLine();
+        method.AppendLine("        return descriptions;");
+        method.AppendLine("    }");
+
+        return method.ToString();
+    }
+
+    static bool IsPow2(object? value)
+    {
+        if (value is int x) return x != 0 && (x & (x - 1)) == 0;
+        return false;
+    }
+
+    private class EnumsSyntaxReceiver : ISyntaxReceiver
+    {
+        public List<EnumDeclarationSyntax> Enums { get; } = new();
+
+        public void OnVisitSyntaxNode(SyntaxNode syntaxNode)
+        {
+            if (syntaxNode is EnumDeclarationSyntax enumDeclarationSyntax
+                && enumDeclarationSyntax.AttributeLists.Any(al => al.Attributes.Any(a => a.Name.ToString() == "GenerateEnumDescriptionUtils")))
+            {
+                Enums.Add(enumDeclarationSyntax);
+            }
+        }
+    }
+}

libs/gen/Garnet.gen.csproj

@@ -0,0 +1,22 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup> 
+    <TargetFrameworks>netstandard2.0</TargetFrameworks>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <LangVersion>Latest</LangVersion>
+    <EnforceExtendedAnalyzerRules>true</EnforceExtendedAnalyzerRules>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.CodeAnalysis.Analyzers">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <None Include="$(OutputPath)\$(AssemblyName).dll" Pack="true" PackagePath="analyzers/dotnet/cs" Visible="false" />
+  </ItemGroup>
+</Project>

libs/server/Garnet.server.csproj

@@ -5,6 +5,7 @@
     <AssemblyOriginatorKeyFile>../../Garnet.snk</AssemblyOriginatorKeyFile>
     <DelaySign>false</DelaySign>
     <EmbedUntrackedSources>true</EmbedUntrackedSources>
+    <EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles>
   </PropertyGroup>
 
   <ItemGroup>
@@ -26,4 +27,9 @@
     <PackageReference Include="System.IdentityModel.Tokens.Jwt" />
   </ItemGroup>
 
+  <ItemGroup>
+    <ProjectReference Include="..\gen\Garnet.gen.csproj" />
+    <Analyzer Include="..\gen\bin\$(Configuration)\netstandard2.0\Garnet.gen.dll" />
+  </ItemGroup>
+
 </Project>