PowerShell/src/System.Management.Automation/engine/interpreter/DynamicInstructionN.cs

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 *
 * Copyright (c) Microsoft Corporation.
 *
 * This source code is subject to terms and conditions of the Apache License, Version 2.0. A
 * copy of the license can be found in the License.html file at the root of this distribution. If
 * you cannot locate the Apache License, Version 2.0, please send an email to
 * dlr@microsoft.com. By using this source code in any fashion, you are agreeing to be bound
 * by the terms of the Apache License, Version 2.0.
 *
 * You must not remove this notice, or any other, from this software.
 *
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 * ***************************************************************************/

using System.Runtime.CompilerServices;

namespace System.Management.Automation.Interpreter
{
    internal sealed partial class DynamicInstructionN : Instruction
    {
        private readonly CallInstruction _target;
        private readonly object _targetDelegate;
        private readonly CallSite _site;
        private readonly int _argumentCount;
        private readonly bool _isVoid;

        public DynamicInstructionN(Type delegateType, CallSite site)
        {
            var methodInfo = delegateType.GetMethod("Invoke");
            var parameters = methodInfo.GetParameters();

            _target = CallInstruction.Create(methodInfo, parameters);
            _site = site;
            _argumentCount = parameters.Length - 1;
            _targetDelegate = site.GetType().GetField("Target").GetValue(site);
        }

        public DynamicInstructionN(Type delegateType, CallSite site, bool isVoid)
            : this(delegateType, site)
        {
            _isVoid = isVoid;
        }

        public override int ProducedStack { get { return _isVoid ? 0 : 1; } }

        public override int ConsumedStack { get { return _argumentCount; } }

        public override int Run(InterpretedFrame frame)
        {
            int first = frame.StackIndex - _argumentCount;
            object[] args = new object[1 + _argumentCount];
            args[0] = _site;
            for (int i = 0; i < _argumentCount; i++)
            {
                args[1 + i] = frame.Data[first + i];
            }

            object ret = _target.InvokeInstance(_targetDelegate, args);
            if (_isVoid)
            {
                frame.StackIndex = first;
            }
            else
            {
                frame.Data[first] = ret;
                frame.StackIndex = first + 1;
            }

            return 1;
        }

        public override string ToString()
        {
            return "DynamicInstructionN(" + _site + ")";
        }
    }
}