MetadataBuilder Classe

Definição

public ref class MetadataBuilder sealed

public sealed class MetadataBuilder

type MetadataBuilder = class

Public NotInheritable Class MetadataBuilder

Herança

Object

MetadataBuilder

Exemplos

Este exemplo mostra como emitir um assembly de aplicativo de console usando MetadataBuilder:

private static readonly Guid s_guid = new Guid("87D4DBE1-1143-4FAD-AAB3-1001F92068E6");
private static readonly BlobContentId s_contentId = new BlobContentId(s_guid, 0x04030201);

private static MethodDefinitionHandle EmitHelloWorld(MetadataBuilder metadata, BlobBuilder ilBuilder)
{
    // Create module and assembly for a console application.
    metadata.AddModule(
        0,
        metadata.GetOrAddString("ConsoleApplication.exe"),
        metadata.GetOrAddGuid(s_guid),
        default(GuidHandle),
        default(GuidHandle));

    metadata.AddAssembly(
        metadata.GetOrAddString("ConsoleApplication"),
        version: new Version(1, 0, 0, 0),
        culture: default(StringHandle),
        publicKey: default(BlobHandle),
        flags: 0,
        hashAlgorithm: AssemblyHashAlgorithm.None);

    // Create references to System.Object and System.Console types.
    AssemblyReferenceHandle mscorlibAssemblyRef = metadata.AddAssemblyReference(
        name: metadata.GetOrAddString("mscorlib"),
        version: new Version(4, 0, 0, 0),
        culture: default(StringHandle),
        publicKeyOrToken: metadata.GetOrAddBlob(
            new byte[] { 0xB7, 0x7A, 0x5C, 0x56, 0x19, 0x34, 0xE0, 0x89 }
            ),
        flags: default(AssemblyFlags),
        hashValue: default(BlobHandle));

    TypeReferenceHandle systemObjectTypeRef = metadata.AddTypeReference(
        mscorlibAssemblyRef,
        metadata.GetOrAddString("System"),
        metadata.GetOrAddString("Object"));

    TypeReferenceHandle systemConsoleTypeRefHandle = metadata.AddTypeReference(
        mscorlibAssemblyRef,
        metadata.GetOrAddString("System"),
        metadata.GetOrAddString("Console"));

    // Get reference to Console.WriteLine(string) method.
    var consoleWriteLineSignature = new BlobBuilder();

    new BlobEncoder(consoleWriteLineSignature).
        MethodSignature().
        Parameters(1,
            returnType => returnType.Void(),
            parameters => parameters.AddParameter().Type().String());

    MemberReferenceHandle consoleWriteLineMemberRef = metadata.AddMemberReference(
        systemConsoleTypeRefHandle,
        metadata.GetOrAddString("WriteLine"),
        metadata.GetOrAddBlob(consoleWriteLineSignature));

    // Get reference to Object's constructor.
    var parameterlessCtorSignature = new BlobBuilder();

    new BlobEncoder(parameterlessCtorSignature).
        MethodSignature(isInstanceMethod: true).
        Parameters(0, returnType => returnType.Void(), parameters => { });

    BlobHandle parameterlessCtorBlobIndex = metadata.GetOrAddBlob(parameterlessCtorSignature);

    MemberReferenceHandle objectCtorMemberRef = metadata.AddMemberReference(
        systemObjectTypeRef,
        metadata.GetOrAddString(".ctor"),
        parameterlessCtorBlobIndex);

    // Create signature for "void Main()" method.
    var mainSignature = new BlobBuilder();

    new BlobEncoder(mainSignature).
        MethodSignature().
        Parameters(0, returnType => returnType.Void(), parameters => { });

    var methodBodyStream = new MethodBodyStreamEncoder(ilBuilder);

    var codeBuilder = new BlobBuilder();
    InstructionEncoder il;
    
    // Emit IL for Program::.ctor
    il = new InstructionEncoder(codeBuilder);

    // ldarg.0
    il.LoadArgument(0); 

    // call instance void [mscorlib]System.Object::.ctor()
    il.Call(objectCtorMemberRef);

    // ret
    il.OpCode(ILOpCode.Ret);

    int ctorBodyOffset = methodBodyStream.AddMethodBody(il);
    codeBuilder.Clear();

    // Emit IL for Program::Main
    var flowBuilder = new ControlFlowBuilder();
    il = new InstructionEncoder(codeBuilder, flowBuilder);

    // ldstr "hello"
    il.LoadString(metadata.GetOrAddUserString("Hello, world"));

    // call void [mscorlib]System.Console::WriteLine(string)
    il.Call(consoleWriteLineMemberRef);

    // ret
    il.OpCode(ILOpCode.Ret);

    int mainBodyOffset = methodBodyStream.AddMethodBody(il);
    codeBuilder.Clear();

    // Create method definition for Program::Main
    MethodDefinitionHandle mainMethodDef = metadata.AddMethodDefinition(
        MethodAttributes.Public | MethodAttributes.Static | MethodAttributes.HideBySig,
        MethodImplAttributes.IL,
        metadata.GetOrAddString("Main"),
        metadata.GetOrAddBlob(mainSignature),
        mainBodyOffset,
        parameterList: default(ParameterHandle));

    // Create method definition for Program::.ctor
    MethodDefinitionHandle ctorDef = metadata.AddMethodDefinition(
        MethodAttributes.Public | MethodAttributes.HideBySig | MethodAttributes.SpecialName | MethodAttributes.RTSpecialName,
        MethodImplAttributes.IL,
        metadata.GetOrAddString(".ctor"),
        parameterlessCtorBlobIndex,
        ctorBodyOffset,
        parameterList: default(ParameterHandle));

    // Create type definition for the special <Module> type that holds global functions
    metadata.AddTypeDefinition(
        default(TypeAttributes),
        default(StringHandle),
        metadata.GetOrAddString("<Module>"),
        baseType: default(EntityHandle),
        fieldList: MetadataTokens.FieldDefinitionHandle(1),
        methodList: mainMethodDef);

    // Create type definition for ConsoleApplication.Program
    metadata.AddTypeDefinition(
        TypeAttributes.Class | TypeAttributes.Public | TypeAttributes.AutoLayout | TypeAttributes.BeforeFieldInit,
        metadata.GetOrAddString("ConsoleApplication"),
        metadata.GetOrAddString("Program"),
        baseType: systemObjectTypeRef,
        fieldList: MetadataTokens.FieldDefinitionHandle(1),
        methodList: mainMethodDef);
    
    return mainMethodDef;
}

private static void WritePEImage(
    Stream peStream,
    MetadataBuilder metadataBuilder,
    BlobBuilder ilBuilder,
    MethodDefinitionHandle entryPointHandle
    )
{
    // Create executable with the managed metadata from the specified MetadataBuilder.
    var peHeaderBuilder = new PEHeaderBuilder(
        imageCharacteristics: Characteristics.ExecutableImage
        );

    var peBuilder = new ManagedPEBuilder(
        peHeaderBuilder,
        new MetadataRootBuilder(metadataBuilder),
        ilBuilder,
        entryPoint: entryPointHandle,
        flags: CorFlags.ILOnly,
        deterministicIdProvider: content => s_contentId);

    // Write executable into the specified stream.
    var peBlob = new BlobBuilder();
    BlobContentId contentId = peBuilder.Serialize(peBlob);
    peBlob.WriteContentTo(peStream);
}

public static void BuildHelloWorldApp()
{
    using var peStream = new FileStream(
        "ConsoleApplication.exe", FileMode.OpenOrCreate, FileAccess.ReadWrite
        );
    
    var ilBuilder = new BlobBuilder();
    var metadataBuilder = new MetadataBuilder();

    MethodDefinitionHandle entryPoint = EmitHelloWorld(metadataBuilder, ilBuilder);
    WritePEImage(peStream, metadataBuilder, ilBuilder, entryPoint);
}

Comentários

A MetadataBuilder classe permite que você gere assemblies programaticamente. Esses assemblies podem ser salvos em um arquivo, ao contrário dos assemblies dinâmicos gerados pela classe AssemblyBuilder, que não dá suporte ao salvamento de assemblies em um arquivo no .NET 5+ e .NET Core.

A MetadataBuilder API opera constructos de metadados de baixo nível, como tabelas ou blobs. Para obter uma maneira mais simples de gerar assemblies dinamicamente usando C#, consulte CSharpCompilation na API roslyn.

O formato dos metadados da CLI é definido pela especificação ECMA-335. Para obter mais informações, consulte Standard ECMA-335 – CLI (Common Language Infrastructure) no site da Ecma International.