ControlFlowBuilder クラス

定義

public ref class ControlFlowBuilder sealed

public sealed class ControlFlowBuilder

type ControlFlowBuilder = class

Public NotInheritable Class ControlFlowBuilder

継承

Object

ControlFlowBuilder

例

この例では、 ControlFlowBuilderを使用して例外ハンドラーを使用してメソッド本体を出力する方法を示します。

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

/* public static void ExceptionBlockTest(int x, int y)
   {
      try
      {
         Console.WriteLine(x / y);
      }
      catch (DivideByZeroException)
      {
         Console.WriteLine("Error: division by zero");
      }
   }
*/

public static InstructionEncoder ControlFlowBuilderDemo(MetadataBuilder metadata, 
    AssemblyReferenceHandle corlibAssemblyRef)
{
    var codeBuilder = new BlobBuilder();
    var flowBuilder = new ControlFlowBuilder();
    var encoder = new InstructionEncoder(codeBuilder, flowBuilder);

    // Get reference to System.Console
    AssemblyReferenceHandle systemConsoleAssemblyRef = metadata.AddAssemblyReference(
        name: metadata.GetOrAddString("System.Console"),
        version: new Version(4, 0, 0, 0),
        culture: default(StringHandle),
        publicKeyOrToken: default(BlobHandle),
        flags: default(AssemblyFlags),
        hashValue: default(BlobHandle));
    
    TypeReferenceHandle consoleTypeRefHandle = metadata.AddTypeReference(
        systemConsoleAssemblyRef,
        metadata.GetOrAddString("System"),
        metadata.GetOrAddString("Console"));

    // Get reference to void System.Console::WriteLine(int32)
    var methodSignature = new BlobBuilder();

    new BlobEncoder(methodSignature).
        MethodSignature(isInstanceMethod: false).
        Parameters(1, returnType => returnType.Void(), parameters => parameters.AddParameter().Type().Int32());

    BlobHandle sigBlobIndex1 = metadata.GetOrAddBlob(methodSignature);

    MemberReferenceHandle refWriteLineInt32 = metadata.AddMemberReference(
        consoleTypeRefHandle,
        metadata.GetOrAddString("WriteLine"),
        sigBlobIndex1);

    // Get reference to void System.Console::WriteLine(string)
    methodSignature = new BlobBuilder();

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

    BlobHandle sigBlobIndex2 = metadata.GetOrAddBlob(methodSignature);

    MemberReferenceHandle refWriteLineString = metadata.AddMemberReference(
        consoleTypeRefHandle,
        metadata.GetOrAddString("WriteLine"),
        sigBlobIndex2);

    // Get reference to System.DivideByZeroException
    TypeReferenceHandle exceptionTypeRefHandle = metadata.AddTypeReference(
        corlibAssemblyRef,
        metadata.GetOrAddString("System"),
        metadata.GetOrAddString("DivideByZeroException"));
    
    LabelHandle labelTryStart = encoder.DefineLabel();
    LabelHandle labelTryEnd = encoder.DefineLabel();
    LabelHandle labelCatchStart = encoder.DefineLabel();
    LabelHandle labelCatchEnd = encoder.DefineLabel();
    LabelHandle labelExit = encoder.DefineLabel();

    flowBuilder.AddCatchRegion(labelTryStart, labelTryEnd, labelCatchStart, labelCatchEnd,
        exceptionTypeRefHandle);

    // .try {
    encoder.MarkLabel(labelTryStart);

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

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

    // div
    encoder.OpCode(ILOpCode.Div);

    // call void [System.Console]System.Console::WriteLine(int32)
    encoder.Call(refWriteLineInt32);

    // leave.s EXIT            
    encoder.Branch(ILOpCode.Leave_s, labelExit);
    encoder.MarkLabel(labelTryEnd);

    // } 
    // catch [System.Runtime]System.DivideByZeroException {
    encoder.MarkLabel(labelCatchStart);

    // pop
    encoder.OpCode(ILOpCode.Pop);
    
    // ldstr "Error: division by zero"
    encoder.LoadString(metadata.GetOrAddUserString("Error: division by zero"));

    // call void [System.Console]System.Console::WriteLine(string)
    encoder.Call(refWriteLineString);

    // leave.s EXIT            
    encoder.Branch(ILOpCode.Leave_s, labelExit);
    encoder.MarkLabel(labelCatchEnd);

    // } EXIT: ret
    encoder.MarkLabel(labelExit);
    encoder.OpCode(ILOpCode.Ret);
    
    return encoder;
}

注釈

ControlFlowBuilder クラスは、InstructionEncoderでエンコードされたメソッド本体に分岐と例外ブロックを作成するために使用されます。 .NETアセンブリの出力の詳細については、MetadataBuilder クラスのドキュメントを参照してください。