MetadataBuilder Klass

Definition

public ref class MetadataBuilder sealed

public sealed class MetadataBuilder

type MetadataBuilder = class

Public NotInheritable Class MetadataBuilder

Arv

Object

MetadataBuilder

Exempel

Det här exemplet visar hur du genererar en konsolprogramsammansättning med hjälp av 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);
}

Kommentarer

Med MetadataBuilder klassen kan du programmatiskt generera sammansättningar. Dessa sammansättningar kan sparas i en fil, till skillnad från dynamiska sammansättningar som genereras av klassen AssemblyBuilder, vilket inte stöder sparande av sammansättningar i en fil på .NET 5+ och .NET Core.

API:et MetadataBuilder använder metadatakonstruktioner på låg nivå, till exempel tabeller eller blobar. Ett enklare sätt att generera sammansättningar dynamiskt med C#finns CSharpCompilation i Roslyn API.

Formatet för CLI-metadata definieras av ECMA-335-specifikationen. Mer information finns i Standard ECMA-335 – Common Language Infrastructure (CLI) på Ecma Internationals webbplats.