搭建项目环境1. 创建 Net Standard 2.0 项目Project SdkMicrosoft.NET.Sdk PropertyGroup TargetFrameworknetstandard2.0/TargetFramework LangVersionlatest/LangVersion IsRoslynComponenttrue/IsRoslynComponent !-- 关键指定为生成器 -- EnforceExtendedAnalyzerRulestrue/EnforceExtendedAnalyzerRules /PropertyGroup ItemGroup PackageReference IncludeMicrosoft.CodeAnalysis.CSharp Version4.9.2 / PackageReference IncludeMicrosoft.CodeAnalysis.Analyzers Version3.3.4 / /ItemGroup /Project2. 生成器完整结构示例// 示例功能自动将自定义类型的属性的内部属性展开为可直接访问的属性 [Generator] // 生成器特性标记同时继承 IIncrementalGenerator internal class FlattenPropsGenerator : IIncrementalGenerator { // 需要实现的方法完成代码生成 public override void Initialize(IncrementalGeneratorInitializationContext context) { // 创建语法提供者查找带有 GenerateFlattenAttribute 的属性进行处理 var propertyPipeline context.SyntaxProvider .CreateSyntaxProvider( predicate: (node, _) QuickCheckAttribute(node), // 快速筛选语义节点 transform: (context, _) TransformClass(context)) // 转换为特定对象便于后续操作 .Where(classInfo classInfo ! null); // 注册生成代码输出 context.RegisterSourceOutput(propertyPipeline, (spc, source) { if (source is ClassFlattenInfo classFlattenInfo) GenerateFlattenedProperties(spc, classFlattenInfo); }); } /*-------------- 以下代码为具体业务实现 --------------*/ // 仅处理特定特性标注的类及属性 private static readonly string flattenPropsAttrFullName typeof(GenerateFlattenPropsAttribute).FullName; private static readonly string flattenAttrFullName typeof(GenerateFlattenAttribute).FullName; // 快速校验当前节点是否需要处理 private static bool QuickCheckAttribute(SyntaxNode node) { // 检查是否为 record if (node is not RecordDeclarationSyntax typeDeclaration) return false; // 检查是否包含特性 return typeDeclaration.AttributeLists.SelectMany(a a.Attributes).Any(a flattenPropsAttrFullName.Contains(a.Name.ToFullString())); } private static ClassFlattenInfo? TransformClass(GeneratorSyntaxContext context) { var typeDeclaration (TypeDeclarationSyntax)context.Node; var semanticModel context.SemanticModel; var compilation semanticModel.Compilation; // 获取 Compilation // 获取类型符号 if (semanticModel.GetDeclaredSymbol(typeDeclaration) is not INamedTypeSymbol symbol) return null; // 检查是否有指定的特性 var flattenPropsAttributeType compilation.GetTypeByMetadataName(flattenPropsAttrFullName); var attribute symbol.GetAttributes().FirstOrDefault(attr SymbolEqualityComparer.Default.Equals(attr.AttributeClass, flattenPropsAttributeType)); if (attribute null) return null; // 查找所有带有特性的属性 var properties new ListPropertyTransformResult(); var attributeType compilation.GetTypeByMetadataName(flattenAttrFullName); foreach (var property in typeDeclaration.Members.OfTypePropertyDeclarationSyntax()) { // 获取属性符号 var propertySymbol semanticModel.GetDeclaredSymbol(property); if (propertySymbol null) continue; // 获取属性类型 if (propertySymbol.Type is not INamedTypeSymbol propertyType) continue; // 检查是否有特性 var attr propertySymbol.GetAttributes().FirstOrDefault(attr SymbolEqualityComparer.Default.Equals(attr.AttributeClass, attributeType)); if (attr null) continue; var attrConfig AttrConfig.CreateFromAttr(attr, context.SemanticModel); // 获取需要展平的属性 properties.Add(new PropertyTransformResult { PropertySymbol propertySymbol, PropertyType propertyType, PropertyName property.Identifier.Text, PropertySyntax property, PropertiesToFlatten propertyType.GetAllProperties() }); } return properties.Count 0 ? null : new ClassFlattenInfo { ContainingType symbol, Properties properties, IsRecord symbol.IsRecord }; } // 根据配置信息生成对应的代码 private static void GenerateFlattenedProperties(SourceProductionContext context, ClassFlattenInfo classFlattenInfo) { var classInfo classFlattenInfo.ContainingType; try { // 生成扁平化属性代码 var code GenerateFlattenPropertiesCode(classFlattenInfo, context); // 添加源文件 var fileName ${classInfo.Name}_FlattenProps.g.cs; context.AddSource(fileName, SourceText.From(code, Encoding.UTF8)); } catch (Exception ex) { // 报告诊断信息 var descriptor new DiagnosticDescriptor(FLATTEN001, Error generating flattened properties, Error: {0}, Generation, DiagnosticSeverity.Error, true); var diagnostic Diagnostic.Create(descriptor, classInfo.DeclaringSyntaxReferences.First().GetSyntax().GetLocation(), ex.Message); context.ReportDiagnostic(diagnostic); } } // 生成扁平化属性代码 private static string GenerateFlattenPropertiesCode(ClassFlattenInfo classFlattenInfo, SourceProductionContext context) { var sb new StringBuilder(); var clsInfo classFlattenInfo.ContainingType; AddGenerateInfo(sb); // 收集所有需要 using 的命名空间 AddUsings(sb, classFlattenInfo); // 添加命名空间 var namespaceName clsInfo.ContainingNamespace.ToDisplayString(); if (!string.IsNullOrEmpty(namespaceName)) sb.AppendLine($namespace {namespaceName};); // 添加类型声明 AddTypeDeclaration(sb, clsInfo); // 添加扁平化属性 AddFlattenedProperties(sb, classFlattenInfo, context); sb.AppendLine(}); // 结束类型声明 return sb.ToString(); } private static void AddUsings(StringBuilder sb, ClassFlattenInfo classFlattenInfo) { // 收集所有需要 using 的命名空间 var usings new HashSetstring(); var clsNsp classFlattenInfo.ContainingType.ContainingNamespace; StackITypeSymbol stack new(classFlattenInfo.Properties.Select(p p.PropertySymbol.Type) .Concat(classFlattenInfo.Properties.SelectMany(prop prop.PropertiesToFlatten .SelectMany(x x.GetAttributes().Select(a a.AttributeClass))).OfTypeITypeSymbol())); while (stack.Count 0) { var _tsym stack.Pop(); // 1. 添加属性类型的命名空间 if (_tsym.ContainingNamespace is { } ns !SymbolEqualityComparer.Default.Equals(ns, clsNsp)) usings.Add(ns.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat)); // 2. 添加属性类型中泛型参数的命名空间 if (_tsym is INamedTypeSymbol namedType namedType.IsGenericType) foreach (var typeArg in namedType.TypeArguments) stack.Push(typeArg); } foreach (var s in usings) sb.AppendLine($using {s};); sb.AppendLine(); } private static void AddTypeDeclaration(StringBuilder sb, INamedTypeSymbol clsInfo) { sb.AppendLine(${clsInfo.DeclaredAccessibility.ToCodeString()} {clsInfo.GetTypeModifiers()} partial {clsInfo.GetTypeKindString()} {clsInfo.Name}); sb.AppendLine({); } private static void AddFlattenedProperties(StringBuilder sb, ClassFlattenInfo classFlattenInfo, SourceProductionContext context) { // 收集所有需要扁平化的属性避免重复 var flattenedProperties new Dictionarystring, (IPropertySymbol, PropertyTransformResult)(); var conflicts new List(string msg, PropertyTransformResult prop)(); // 现有类的属性 var existingProperty new HashSetstring(classFlattenInfo.ContainingType.GetMembers().OfTypeIPropertySymbol().Select(x x.Name)); foreach (var propertyInfo in classFlattenInfo.Properties) { foreach (var prop in propertyInfo.PropertiesToFlatten) { var propertyName prop.Name; var msg flattenedProperties.ContainsKey(propertyName) ? ${propertyInfo.PropertyName}.{propertyName} : ; if (msg existingProperty.Contains(propertyName)) msg ${propertyInfo.PropertyName}.{propertyName} (已存在于类中); if (msg ! ) { conflicts.Add((msg, propertyInfo)); continue; } flattenedProperties[propertyName] (prop, propertyInfo); } } // 报告冲突 if (conflicts.Count 0) { const string descId FLATTEN002; const string msgFmt 检测到属性名称冲突: {0}; foreach (var (msg, prop) in conflicts) { var _msg string.Format(msgFmt, msg); // 控制生成文件提示 sb.AppendLine(${indent}// {DiagnosticSeverity.Warning} {descId}: {_msg}); // 报告诊断信息 var desc new DiagnosticDescriptor(descId, 扁平化属性冲突, _msg, CodeGeneration, DiagnosticSeverity.Error, true); context.ReportDiagnostic(Diagnostic.Create(desc, prop.PropertySyntax.GetLocation())); } sb.AppendLine(); } // 生成属性代码 foreach (var (prop, propertyInfo) in flattenedProperties.Values) { GenerateFlattenedPropertyCode(sb, prop, propertyInfo.PropertyName); sb.AppendLine(); } } private static void GenerateFlattenedPropertyCode(StringBuilder sb, IPropertySymbol sourceProperty, string sourcePropertyName) { var propertyName sourceProperty.Name; var propertyType sourceProperty.Type.ToDisplayString(SymbolDisplayFormat.MinimallyQualifiedFormat); var accessibility sourceProperty.DeclaredAccessibility.ToCodeString(); // 添加 XML 注释 sb.AppendLine(${indent}/// summary); sb.AppendLine(${indent}/// 从 {sourcePropertyName}.{propertyName} 扁平化的属性); sb.AppendLine(${indent}/// /summary); // 生成属性 var hasGetter sourceProperty.GetMethod ! null; var hasSetter sourceProperty.SetMethod ! null !sourceProperty.SetMethod.IsInitOnly; // 处理 required 修饰符 var isRequired sourceProperty.IsRequired ? required : ; if (hasGetter hasSetter) { // 获取访问器的可访问性 var getterAccess sourceProperty.GetMethod!.DeclaredAccessibility.ToCodeString(); var setterAccess sourceProperty.SetMethod!.DeclaredAccessibility.ToCodeString(); var getterMod getterAccess ! accessibility ? ${getterAccess} : ; var setterMod setterAccess ! accessibility ? ${setterAccess} : ; sb.AppendLine(${indent}{accessibility} {isRequired}{propertyType} {propertyName}); sb.AppendLine(${indent}{{); sb.AppendLine(${indent}{indent}{getterMod}get {sourcePropertyName}.{propertyName};); sb.AppendLine(${indent}{indent}{setterMod}set {sourcePropertyName}.{propertyName} value;); sb.Append(${indent}}}); } else if (hasGetter) { sb.AppendLine(${indent}{accessibility} {isRequired}{propertyType} {propertyName} {sourcePropertyName}.{propertyName};); } else if (hasSetter) { var setterAccess sourceProperty.SetMethod!.DeclaredAccessibility.ToCodeString(); var setterMod setterAccess ! accessibility ? ${setterAccess} : ; sb.AppendLine(${indent}{accessibility} {isRequired}{propertyType} {propertyName}); sb.AppendLine(${indent}{{); sb.AppendLine(${indent}{indent}{setterMod}set {sourcePropertyName}.{propertyName} value;); sb.Append(${indent}}}); } } /// summary /// 属性转换结果 /// /summary struct PropertyTransformResult { public IPropertySymbol PropertySymbol { get; set; } public INamedTypeSymbol PropertyType { get; set; } public string PropertyName { get; set; } public PropertyDeclarationSyntax PropertySyntax { get; set; } // 获取源类型的所有公共实例属性非索引器 public IReadOnlyListIPropertySymbol PropertiesToFlatten { get; set; } } struct ClassFlattenInfo { public INamedTypeSymbol ContainingType { get; set; } public ListPropertyTransformResult Properties { get; set; } public bool IsRecord { get; set; } } } [AttributeUsage(AttributeTargets.Property, AllowMultiple false)] public sealed class GenerateFlattenAttribute : Attribute{}3. 使用示例public record Person { public string? Name { get; set; } } [GenerateFlattenProps] public partial record Student { [GenerateFlatten] Person Person { get; set; } new Person(); }如何利用 nuget 方便使用生成器项目无法直接被其他项目作为依赖项目引用需要借助 nuget修改项目配置文件使生成器项目为 nuget 项目每次修改生成器项目后重新生成然后在测试项目中重新安装或更新 nuget!-- 开发版配置 -- PropertyGroup Condition$(Configuration) Debug VersionSuffixalpha/VersionSuffix /PropertyGroup !-- 预览版配置 -- PropertyGroup Condition$(Configuration) Preview VersionSuffixbeta/VersionSuffix /PropertyGroup !-- 正式版配置无后缀 -- PropertyGroup Condition$(Configuration) Release VersionSuffix/VersionSuffix /PropertyGroup PropertyGroup IncludeBuildOutputfalse/IncludeBuildOutput IsAnalyzertrue/IsAnalyzer EnforceExtendedAnalyzerRulestrue/EnforceExtendedAnalyzerRules !-- 每次构建自动递增版本号 -- GeneratePackageOnBuildtrue/GeneratePackageOnBuild PackageOutputPath$(SolutionDir)local-packages/PackageOutputPath PackageIdArch.CodeGenerator/PackageId Version1.2.3/Version Version Condition$(VersionSuffix) ! $(Version)-$(VersionSuffix)/Version PackageVersion$(Version)/PackageVersion Authors会写代码的建筑师/Authors Description一个源码生成器/Description !-- 不包含构建输出 -- IncludeBuildOutputfalse/IncludeBuildOutput !-- 包类型 -- PackageTypeDependency/PackageType NoPackageAnalysistrue/NoPackageAnalysis IncludeSourceGeneratorInPackagetrue/IncludeSourceGeneratorInPackage !-- 生成符号包 -- IncludeSymbolstrue/IncludeSymbols SymbolPackageFormatsnupkg/SymbolPackageFormat !-- 包含源码便于调试 -- IncludeSourcetrue/IncludeSource PublishRepositoryUrltrue/PublishRepositoryUrl EmbedUntrackedSourcestrue/EmbedUntrackedSources /PropertyGroup如何让生成器项目同时作为 dll 项目其他引用项目可与生成器共享本项目中定义的类使用生成器的项目可直接从 nuget 安装即可使用本项目定义的类型比如 GenerateFlattenAttribute 可直接定义在当前项目便于统一管理!-- 在打包前复制一份用于 analyzers -- Target NameCopyForPackage BeforeTargetsGenerateNuspec Copy SourceFiles$(OutputPath)$(AssemblyName).dll DestinationFiles$(OutputPath)analyzers/$(AssemblyName).dll SkipUnchangedFilestrue / /Target ItemGroup PackageReference IncludeMicrosoft.CodeAnalysis.CSharp.Workspaces Version4.6.0 / !-- 作为普通程序集打包 -- None Include$(OutputPath)$(AssemblyName).dll Packtrue PackagePathlib/netstandard2.0 / !-- 使用复制后的文件打包到 analyzers -- None Include$(OutputPath)analyzers/$(AssemblyName).dll Packtrue PackagePathanalyzers/dotnet/cs Visiblefalse / /ItemGroup可能遇到的问题首次引入源生成器项目时报错需要重启 vs 并重新生成解决方案