.net源生成器必须知道的4套类型

xiangji2026-08-10 9:05

前言

  • .net有4套类型
  • 每一套类型有各自的作用
  • 部分类型之间可以相互转化

1. TypeSyntax

  • 全称Microsoft.CodeAnalysis.CSharp.Syntax.TypeSyntax
  • 用于在SyntaxTree中引用类型

1.1 TypeSyntax常用子类

  • PredefinedTypeSyntax
  • IdentifierNameSyntax
  • QualifiedNameSyntax
  • GenericNameSyntax
  • ArrayTypeSyntax
  • NullableTypeSyntax
  • OmittedTypeArgumentSyntax

1.2 PredefinedTypeSyntax

  • 系统预定义类型

1.2.1 预定义类型有16种

  • 由以下16种SyntaxKind定义预定义类型
  • SyntaxKind.BoolKeyword
  • SyntaxKind.ByteKeyword
  • SyntaxKind.SByteKeyword
  • SyntaxKind.IntKeyword
  • SyntaxKind.UIntKeyword
  • SyntaxKind.ShortKeyword
  • SyntaxKind.UShortKeyword
  • SyntaxKind.LongKeyword
  • SyntaxKind.ULongKeyword
  • SyntaxKind.FloatKeyword
  • SyntaxKind.DoubleKeyword
  • SyntaxKind.DecimalKeyword
  • SyntaxKind.StringKeyword
  • SyntaxKind.CharKeyword
  • SyntaxKind.ObjectKeyword
  • SyntaxKind.VoidKeyword

1.2.2 EasySyntax语法

  • SyntaxGenerator.BoolType
  • SyntaxGenerator.ByteType
  • SyntaxGenerator.SByteType
  • SyntaxGenerator.IntType
  • SyntaxGenerator.UIntType
  • SyntaxGenerator.ShortType
  • SyntaxGenerator.UShortType
  • SyntaxGenerator.LongType
  • SyntaxGenerator.ULongType
  • SyntaxGenerator.FloatType
  • SyntaxGenerator.DoubleType
  • SyntaxGenerator.DecimalType
  • SyntaxGenerator.StringType
  • SyntaxGenerator.CharType
  • SyntaxGenerator.ObjectType
  • SyntaxGenerator.VoidType

1.2.3 Roslyn原始语法

  • SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.BoolKeyword))
  • SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.ByteKeyword))
  • SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.SByteKeyword))
  • SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.IntKeyword))
  • SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.UIntKeyword))
  • SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.ShortKeyword))
  • SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.UShortKeyword))
  • SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.LongKeyword))
  • SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.ULongKeyword))
  • SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.FloatKeyword))
  • SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.DoubleKeyword))
  • SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.DecimalKeyword))
  • SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.StringKeyword))
  • SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.CharKeyword))
  • SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.ObjectKeyword))
  • SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.VoidKeyword))

1.3 IdentifierNameSyntax

  • 标识名,这里作为类型标识名

1.3.1 简单类名

  • SyntaxFactory.IdentifierName("User")

1.3.2 含命名空间类名

  • SyntaxFactory.IdentifierName("Models.User")
  • 用于指定命名空间

1.3.3 含全局限定类名

  • SyntaxFactory.IdentifierName("global::Models.User")
  • 用于排除命名空间不明确
  • 比如在A、B、C三个命名空间下,Models.User的4种分别是(A.Models.User、B.Models.User、C.Models.User和Models.User)
  • 使用global::Models.User就没有歧义

1.4 QualifiedNameSyntax

  • 前缀类型(含命名空间)

1.4.1 EasySyntax语法

  • SyntaxFactory.IdentifierName("User").Qualified("Models");

1.4.2 Roslyn原始语法

  • SyntaxFactory.QualifiedName(SyntaxFactory.IdentifierName("Models"), "User")

1.5 GenericNameSyntax

1.5.1 EasySyntax语法

  • SyntaxGenerator.Generic("List", SyntaxGenerator.IntType);

1.5.2 Roslyn原始语法

  • SyntaxFactory.GenericName(SyntaxFactory.Identifier("List"), SyntaxFactory.TypeArgumentList(SyntaxFactory.SeparatedList(SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.IntKeyword)))))

1.6 ArrayTypeSyntax

  • 数组类型

1.6.1 EasySyntax语法

  • SyntaxGenerator.IntType.Array();

1.6.2 Roslyn原始语法

  • SyntaxFactory.ArrayType(SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.IntKeyword)), SyntaxFactory.SingletonList(SyntaxFactory.ArrayRankSpecifier(SyntaxFactory.SingletonSeparatedList(SyntaxFactory.OmittedArraySizeExpression()))))

1.7 NullableTypeSyntax

  • 可空类型

1.7.1 EasySyntax语法

  • SyntaxFactory.NullableType(SyntaxGenerator.IntType);

1.7.2 Roslyn原始语法

  • SyntaxFactory.NullableType(SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.IntKeyword)));

1.8 OmittedTypeArgumentSyntax

  • 泛型匿名类型参数
  • 使用方法SyntaxFactory.OmittedTypeArgument()创建
  • 需要结合泛型来使用
csharp 复制代码 
var listIntType = SyntaxGenerator.Generic("List", SyntaxFactory.OmittedTypeArgument());
var code = listIntType.ToFullString();
Assert.Equal("List<>", code);

1.9 TypeSyntax的用法灵活

2. TypeDeclarationSyntax

  • 全称Microsoft.CodeAnalysis.CSharp.Syntax.TypeDeclarationSyntax
  • 用于定义类型

2.1 TypeDeclarationSyntax常用子类

  • ClassDeclarationSyntax
  • StructDeclarationSyntax
  • InterfaceDeclarationSyntax
  • RecordDeclarationSyntax
  • ExtensionBlockDeclarationSyntax

2.2 ClassDeclarationSyntax

  • 定义类
  • SyntaxFactory.ClassDeclaration("User")

2.3 StructDeclarationSyntax

  • 定义结构体
  • SyntaxFactory.StructDeclaration("User")

2.3 InterfaceDeclarationSyntax

  • 定义接口
  • SyntaxFactory.InterfaceDeclaration("IEntityId")

2.4 RecordDeclarationSyntax

  • 定义记录

2.4.1 EasySyntax语法

csharp 复制代码 
var record = SyntaxGenerator.RecordDeclaration("Person")
    .AddParameterListParameters(
        SyntaxGenerator.StringType.Parameter("Name")
    )
    .WithSemicolonToken();

2.4.2 Roslyn原始语法

csharp 复制代码 
var record = SyntaxFactory.RecordDeclaration(SyntaxFactory.Token(SyntaxKind.RecordKeyword), "Person")
    .AddParameterListParameters(
        SyntaxFactory.Parameter(SyntaxFactory.Identifier("Name"))
            .WithType(SyntaxFactory.PredefinedType(SyntaxFactory.Token(SyntaxKind.StringKeyword)))
    )
    .WithSemicolonToken(SyntaxFactory.Token(SyntaxKind.SemicolonToken));

2.5 ExtensionBlockDeclarationSyntax

  • 扩展块,是csharp14新增扩展方法语法
  • 使用SyntaxFactory.ExtensionBlockDeclaration创建

2.5.1 ExtensionBlockDeclarationSyntax示例

csharp 复制代码 
var userIdType = SyntaxFactory.IdentifierName("UserId");
var userId = SyntaxFactory.IdentifierName("userId");
var incrementMethod = userIdType.Method("Increment")
    .ToBuilder()
    .Return(userIdType.New([userId.Access("Original").Add(SyntaxGenerator.Literal(1))]))
    .Public();
var decreaseMethod = userIdType.Method("Decrease")
    .ToBuilder()
    .Return(userIdType.New([userId.Access("Original").Subtract(SyntaxGenerator.Literal(1))]))
    .Public();

var extension = SyntaxFactory.ExtensionBlockDeclaration()
    .AddParameterListParameters(userIdType.Parameter(userId.Identifier))
    .AddMembers(incrementMethod, decreaseMethod)
    .WithOpenBraceToken(SyntaxFactory.Token(SyntaxKind.OpenBraceToken))
    .WithCloseBraceToken(SyntaxFactory.Token(SyntaxKind.CloseBraceToken));
var type = SyntaxFactory.ClassDeclaration("UserIdExtension")
    .Public()
    .Static()
    .AddMembers(extension);

2.5.2 ExtensionBlockDeclarationSyntax示例生成代码

  • 静态类型UserIdExtension中增加一个扩展块
  • 扩展块中用实例方法定义扩展方法
csharp 复制代码 
public static class UserIdExtension
{
    extension(UserId userId)
    {
        public UserId Increment()
        {
            return new UserId(userId.Original + 1);
        }

        public UserId Decrease()
        {
            return new UserId(userId.Original - 1);
        }
    }
}

3. ITypeSymbol

  • 全称Microsoft.CodeAnalysis.ITypeSymbol
  • 用于描述类型的编译符号的接口
  • 特别注意,ITypeSymbol和反射的Type还不是一回事

3.1 46种SpecialType

  • SpecialType与前面的预定义类型类似,就是系统类
  • 通过以下46种枚举SpecialType来定义
  • SpecialType.System_Runtime_CompilerServices_InlineArrayAttribute
  • SpecialType.System_Object
  • SpecialType.System_Enum
  • SpecialType.System_MulticastDelegate
  • SpecialType.System_Delegate
  • SpecialType.System_ValueType
  • SpecialType.System_Void
  • SpecialType.System_Boolean
  • SpecialType.System_Char
  • SpecialType.System_SByte
  • SpecialType.System_Byte
  • SpecialType.System_Int16
  • SpecialType.System_UInt16
  • SpecialType.System_Int32
  • SpecialType.System_UInt32
  • SpecialType.System_Int64
  • SpecialType.System_UInt64
  • SpecialType.System_Decimal
  • SpecialType.System_Single
  • SpecialType.System_Double
  • SpecialType.System_String
  • SpecialType.System_IntPtr
  • SpecialType.System_UIntPtr
  • SpecialType.System_Array
  • SpecialType.System_Collections_IEnumerable
  • SpecialType.System_Collections_Generic_IEnumerable_T
  • SpecialType.System_Collections_Generic_IList_T
  • SpecialType.System_Collections_Generic_ICollection_T
  • SpecialType.System_Collections_IEnumerator
  • SpecialType.System_Collections_Generic_IEnumerator_T
  • SpecialType.System_Collections_Generic_IReadOnlyList_T
  • SpecialType.System_Collections_Generic_IReadOnlyCollection_T
  • SpecialType.System_Nullable_T
  • SpecialType.System_DateTime
  • SpecialType.System_Runtime_CompilerServices_IsVolatile
  • SpecialType.System_IDisposable
  • SpecialType.System_TypedReference
  • SpecialType.System_ArgIterator
  • SpecialType.System_RuntimeArgumentHandle
  • SpecialType.System_RuntimeFieldHandle
  • SpecialType.System_RuntimeMethodHandle
  • SpecialType.System_RuntimeTypeHandle
  • SpecialType.System_IAsyncResult
  • SpecialType.System_AsyncCallback
  • SpecialType.System_Runtime_CompilerServices_RuntimeFeature
  • SpecialType.System_Runtime_CompilerServices_PreserveBaseOverridesAttribute

3.2 获取系统类

  • 通过Compilation.GetSpecialType获取系统类
csharp 复制代码 
INamedTypeSymbol GetSpecialType(SpecialType specialType);

3.3 按类型名获取

  • 通过Compilation.GetTypeByMetadataName获取类
csharp 复制代码 
var service = SyntaxTreeDriver.CreateDriver();
var source = @"namespace Tests;
    public enum MyColor : int
    {
        Red,
        Green,
        Blue
    };
    var color = MyColor.Red;";
var compilation = service.Compile(source);
var enumType = compilation.GetTypeByMetadataName("Tests.MyColor");
Assert.NotNull(enumType);

3.4 泛型

  • 通过Construct方法构造泛型
csharp 复制代码 
var service = SyntaxTreeDriver.CreateDriver();
var compilation = service.Compile("");
var intType = compilation.GetSpecialType(SpecialType.System_Int32);
// System.Collections.Generic.IList<int>
var genericType = compilation.GetSpecialType(SpecialType.System_Collections_Generic_IList_T)
    .Construct(intType);

4. Type

  • 全称System.Type
  • 用于反射类型信息

4.1 反射获取Type

csharp 复制代码 
Type type = typeof(User);

5. 4套类型的生命周期和转化流程

  • 第一阶段是语法树,存在TypeSyntax和TypeDeclarationSyntax
  • 第二阶段是编译,转化为ITypeSymbol
  • 第三阶段是链接符号生成程序集,转化为Type

6. TypeDeclarationSyntax转ITypeSymbol

  • 编译含TypeDeclarationSyntax的SyntaxTree
  • 从编译信息中获取INamedTypeSymbol
  • 以下示例使用CSharpCompilation.Create调用编译与日常用IDE编译是一回事
csharp 复制代码 
// record User(string Name);
var declaration = SyntaxGenerator.RecordDeclaration("User")
    .AddParameterListParameters(SyntaxGenerator.StringType.Parameter("Name"));
var unit = SyntaxFactory.CompilationUnit()
    .AddMembers(declaration);
var compilation = CSharpCompilation.Create("Tests", [unit.SyntaxTree]);
INamedTypeSymbol? userSymbol = compilation.GetTypeByMetadataName("User");
Assert.NotNull(userSymbol);

7. TypeSyntax转ITypeSymbol

7.1 NullableTypeSyntax转化为SpecialType.System_Nullable_T的实现类

csharp 复制代码 
NullableTypeSyntax nullableSyntax = SyntaxFactory.NullableType(SyntaxGenerator.IntType);
var service = SyntaxTreeDriver.CreateDriver();
var compilation = service.Compile("");
INamedTypeSymbol? symbol= compilation.GetSymbol(nullableSyntax);
Assert.NotNull(symbol);
var nullableSymbol = compilation.GetSpecialType(SpecialType.System_Nullable_T);
Assert.True(symbol.IsGenericType(nullableSymbol));

7.2 PredefinedTypeSyntax转化为系统类型

  • 16种PredefinedTypeSyntax都能转化为对应的ITypeSymbol的系统类型
  • 使用Compilation.GetSymbol扩展方法转化
csharp 复制代码 
var service = SyntaxTreeDriver.CreateDriver();
var compilation = service.Compile("");
var intType = SyntaxGenerator.IntType;
INamedTypeSymbol symbol = compilation.GetSymbol(intType);
Assert.Equal(SpecialType.System_Int32, symbol.SpecialType);

7.3 ArrayTypeSyntax转化为数组类型

  • 使用Compilation.GetSymbol扩展方法转化
csharp 复制代码 
ArrayTypeSyntax arraySyntax = SyntaxGenerator.IntType.Array();
var service = SyntaxTreeDriver.CreateDriver();
var compilation = service.Compile("");
IArrayTypeSymbol? arraySymbol = compilation.GetSymbol(arraySyntax);
Assert.NotNull(arraySymbol);

7.4 GenericNameSyntax转化为泛型

  • 泛型转化为GenericNameSyntax或含GenericNameSyntax的QualifiedNameSyntax
csharp 复制代码 
GenericNameSyntax genericSyntax = SyntaxGenerator.Generic("System.Collections.Generic.IList", SyntaxGenerator.IntType);
var service = SyntaxTreeDriver.CreateDriver()
     .Reference<object>();
var compilation = service.Compile("");
if(compilation.GetSymbol(genericSyntax) is not INamedTypeSymbol genericSymbol)
{
    Assert.Fail();
    return;
}
var listSymbol = compilation.GetSpecialType(SpecialType.System_Collections_Generic_IList_T);
Assert.True(genericSymbol.IsGenericType(listSymbol));

8. ITypeSymbol转Type

  • Compilation.Emit把Compilation转化为Assembly,把ITypeSymbol转化为Type
  • 以下示例先把TypeDeclarationSyntax转ITypeSymbol,再把ITypeSymbol转化为Type
  • 其中SyntaxTreeDriver封装了CSharpCompilation,方便添加引用
  • 其中ScriptLoadContext封装了Compilation.Emit操作
csharp 复制代码 
// record User(string Name);
var declaration = SyntaxGenerator.RecordDeclaration("User")
    .AddParameterListParameters(SyntaxGenerator.StringType.Parameter("Name"));
var unit = SyntaxFactory.CompilationUnit()
    .AddMembers(declaration);
var driver = SyntaxTreeDriver.CreateDriver()
    .Reference<object>();
var compilation = driver.Compile(unit.SyntaxTree);
INamedTypeSymbol? userSymbol = compilation.GetTypeByMetadataName("User");
Assert.NotNull(userSymbol);
using var context = new ScriptLoadContext();
var assembly = context.GetAssembly(compilation);
Type? type = assembly.GetType("User");
Assert.NotNull(type);

9. ITypeSymbol转TypeSyntax

9.1 EasySyntax语法默认转化方法

  • 调用EasySyntax语法的扩展方法ToSyntax转化

9.1.1 可空类型转化为NullableTypeSyntax

csharp 复制代码 
var service = SyntaxTreeDriver.CreateDriver();
var compilation = service.Compile("");
var intType = compilation.GetSpecialType(SpecialType.System_Int32);
var nullable = compilation.GetSpecialType(SpecialType.System_Nullable_T)
    .Construct(intType);
if (nullable.ToSyntax() is not NullableTypeSyntax syntax)
{
    Assert.Fail();
    return;
}
var code = syntax.NormalizeWhitespace().ToFullString();
Assert.Equal("int?", code);

9.1.2 预定义类型转化为PredefinedTypeSyntax

csharp 复制代码 
var service = SyntaxTreeDriver.CreateDriver();
var compilation = service.Compile("");
var intType = compilation.GetSpecialType(SpecialType.System_Int32);
if(intType.ToSyntax() is not PredefinedTypeSyntax syntax)
{
    Assert.Fail();
    return;
}
var code = syntax.NormalizeWhitespace().ToFullString();
Assert.Equal("int", code);

9.1.3 数组转化为ArrayTypeSyntax

csharp 复制代码 
var service = SyntaxTreeDriver.CreateDriver();
var compilation = service.Compile("");
var intType = compilation.GetSpecialType(SpecialType.System_Int32);
var arrayType = compilation.CreateArrayTypeSymbol(intType, 1);
if (arrayType.ToSyntax() is not ArrayTypeSyntax syntax)
{
    Assert.Fail();
    return;
}
var code = syntax.NormalizeWhitespace().ToFullString();
Assert.Equal("int[]", code);

9.1.4 泛型转化为GenericNameSyntax

  • 泛型转化为GenericNameSyntax或含GenericNameSyntax的QualifiedNameSyntax
csharp 复制代码 
var service = SyntaxTreeDriver.CreateDriver();
var compilation = service.Compile("");
var intType = compilation.GetSpecialType(SpecialType.System_Int32);
var genericType = compilation.GetSpecialType(SpecialType.System_Collections_Generic_IList_T)
    .Construct(intType);
var syntax = genericType.ToSyntax();
if (syntax is not GenericNameSyntax
    && (syntax is not QualifiedNameSyntax qualifiedSyntax || qualifiedSyntax.Right is not GenericNameSyntax))
{
    Assert.Fail();
    return;
}
var code = syntax.NormalizeWhitespace().ToFullString();
Assert.Equal("System.Collections.Generic.IList<int>", code);

9.2 确人在当前命名空间下使用类名即可

  • 使调用EasySyntax语法的扩展方法ToMiniName
csharp 复制代码 
var service = SyntaxTreeDriver.CreateDriver();
var compilation = service.Compile("");
var dateTimeType = compilation.GetSpecialType(SpecialType.System_DateTime);
var syntax = dateTimeType.ToMiniName();
var code = syntax.NormalizeWhitespace().ToFullString();
Assert.Equal("DateTime", code);

9.3 转化为含全局限定类名

  • 调用EasySyntax语法的扩展方法ToGlobalName
csharp 复制代码 
var service = SyntaxTreeDriver.CreateDriver();
var compilation = service.Compile("");
var dateTimeType = compilation.GetSpecialType(SpecialType.System_DateTime);
var syntax = dateTimeType.ToGlobalName();
var code = syntax.NormalizeWhitespace().ToFullString();
Assert.Equal("global::System.DateTime", code);

10. 结语

  • 4套类型的生命周期就是我们代码的"前世、今生和未来"
  • 熟悉这些能更好的理解代码工作的机制
  • 开发.net源生成器这些更是必须掌握的技能
  • 以上例子由Roslyn及其简单封装来支持的
  • Roslyn主要组件: Microsoft.CodeAnalysis.CSharp、Microsoft.CodeAnalysis.CSharp.Scripting
  • 封装组件可以用于.net源生成器的开发:
  • dotnet add package Hand.Generators.EasySyntax --version 0.2.1.3
  • dotnet add package Hand.GenerateCore --version 0.2.1.5
  • dotnet add package Hand.Generators.SyntaxScripting --version 0.2.1.3-alpha

源码托管地址: https://github.com/donetsoftwork/Hand.Generators ，欢迎大家直接查看源码。

gitee同步更新:https://gitee.com/donetsoftwork/hand.-generators

如果大家喜欢请动动您发财的小手手帮忙点一下Star,谢谢！！！

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