/// <summary>
/// Gets the delegate associated with the LambdaExpression.
/// Either it uses cached MethodInfo and creates delegate from it, or it will generate
/// completely new dynamic method, store it in a cache and use it to create the delegate.
/// </summary>
private static Delegate GetDelegateForInterpreter(InterpreterState state, LambdaExpression lambda)
{
MethodInfo method;
if (!LambdaInvoker.TryGetGenericInvokeMethod(lambda.Parameters.Count, out method) || HasByRefParameter(lambda))
{
return(GenerateDelegateForInterpreter(state, lambda));
}
Type[] signature = GetSignature(lambda);
method = method.MakeGenericMethod(signature);
return(ReflectionUtils.CreateDelegate(method, lambda.Type, new LambdaInvoker(lambda, state)));
}
/// <summary>
/// The core of the interpreter, calling back onto itself via delegates.
/// </summary>
private static MethodInfo CreateDelegateForInterpreter(Type type)
{
Debug.Assert(type != typeof(Delegate) && typeof(Delegate).IsAssignableFrom(type));
//
// Get the desired signature
//
MethodInfo invoke = type.GetMethod("Invoke");
ParameterInfo[] parameters = invoke.GetParameters();
string name = "Interpreted_" + Interlocked.Increment(ref _DelegateCounter);
Type[] signature = CreateInterpreterSignature(parameters);
DynamicILGen il = Snippets.Shared.CreateDynamicMethod(name, invoke.ReturnType, signature, false);
// Collect all arguments received by the delegate into an array
// and pass them to the Interpreter along with the LambdaInvoker
// LambdaInvoker
il.EmitLoadArg(0);
int count = parameters.Length;
// Create the array
il.EmitInt(count);
il.Emit(OpCodes.Newarr, typeof(object));
for (int i = 0; i < count; i++)
{
il.Emit(OpCodes.Dup);
il.EmitInt(i);
il.EmitLoadArg(i + 1);
EmitExplicitCast(il, parameters[i].ParameterType, typeof(object));
il.EmitStoreElement(typeof(object));
}
// Call back to interpreter
il.EmitCall(LambdaInvoker.GetInvokeMethod());
// Cast back to the delegate return type
EmitExplicitCast(il, typeof(object), invoke.ReturnType);
// And return whatever the result was.
il.Emit(OpCodes.Ret);
//
// We are done (for now), finish the MethodInfo
//
return(il.Finish());
}
