InstructionEncoder Struct

Definizione

public value class InstructionEncoder

public readonly struct InstructionEncoder

public struct InstructionEncoder

type InstructionEncoder = struct

Public Structure InstructionEncoder

Ereditarietà

Object

ValueType

InstructionEncoder

Esempio

In questo esempio viene illustrato come generare un corpo del metodo usando InstructionEncoder:

// The following code emits a method body similar to this C# code:

/*public static double CalcRectangleArea(double length, double width)
{
    if (length < 0.0)
    {
        throw new ArgumentOutOfRangeException("length");
    }

    if (width < 0.0)
    {
        throw new ArgumentOutOfRangeException("width");
    }

    return length * width;
}*/

private static InstructionEncoder EmitMethodBody(MetadataBuilder metadata, AssemblyReferenceHandle corlibAssemblyRef)
{
    var codeBuilder = new BlobBuilder();
    var encoder = new InstructionEncoder(codeBuilder, new ControlFlowBuilder());

    // Get a reference to the System.ArgumentOutOfRangeException type
    TypeReferenceHandle typeRefHandle = metadata.AddTypeReference(
    corlibAssemblyRef,
    metadata.GetOrAddString("System"),
    metadata.GetOrAddString("ArgumentOutOfRangeException"));

    // Signature: .ctor(string)
    var ctorSignature = new BlobBuilder();

    new BlobEncoder(ctorSignature).
        MethodSignature(isInstanceMethod: true).
        Parameters(1, returnType => returnType.Void(), parameters => parameters.AddParameter().Type().String());

    BlobHandle ctorBlobIndex = metadata.GetOrAddBlob(ctorSignature);

    // Get a reference to the System.ArgumentOutOfRangeException constructor
    MemberReferenceHandle ctorMemberRef = metadata.AddMemberReference(
        typeRefHandle,
        metadata.GetOrAddString(".ctor"),
        ctorBlobIndex);

    LabelHandle label1 = encoder.DefineLabel();
    LabelHandle label2 = encoder.DefineLabel();

    // ldarg.0
    encoder.OpCode(ILOpCode.Ldarg_0);

    // ldc.r8 0
    encoder.LoadConstantR8(0);

    // bge.un.s LABEL1
    encoder.Branch(ILOpCode.Bge_un_s, label1);

    // ldstr "length"
    encoder.LoadString(metadata.GetOrAddUserString("length"));

    // newobj instance void [System.Runtime]System.ArgumentOutOfRangeException::.ctor(string)
    encoder.OpCode(ILOpCode.Newobj);
    encoder.Token(ctorMemberRef);

    // throw
    encoder.OpCode(ILOpCode.Throw);

    // LABEL1: ldarg.1
    encoder.MarkLabel(label1);
    encoder.OpCode(ILOpCode.Ldarg_1);

    // ldc.r8 0
    encoder.LoadConstantR8(0);

    // bge.un.s LABEL2
    encoder.Branch(ILOpCode.Bge_un_s, label2);

    // ldstr "width"
    encoder.LoadString(metadata.GetOrAddUserString("width"));

    // newobj instance void [System.Runtime]System.ArgumentOutOfRangeException::.ctor(string)
    encoder.OpCode(ILOpCode.Newobj);
    encoder.Token(ctorMemberRef);

    // throw
    encoder.OpCode(ILOpCode.Throw);

    // LABEL2: ldarg.0
    encoder.MarkLabel(label2);
    encoder.OpCode(ILOpCode.Ldarg_0);

    // ldarg.1
    encoder.OpCode(ILOpCode.Ldarg_1);

    // mul
    encoder.OpCode(ILOpCode.Mul);

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

    return encoder;
}

Commenti

La InstructionEncoder classe viene usata per generare istruzioni CIL che costituiscono un corpo del metodo. Per un esempio completo di creazione di un metodo, vedere la documentazione della MetadataBuilder classe.