/* ****************************************************************************
 *
 * 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.
 *
 *
 * ***************************************************************************/

using System.Collections.Generic;
using System;
using System.Diagnostics;
using Microsoft.Scripting.Utils;
namespace Microsoft.Scripting.Interpreter {
    internal sealed class LoadObjectInstruction : Instruction {
        private readonly object _value;

        internal LoadObjectInstruction(object value) {
            _value = value;
        }

        public override int ProducedStack { get { return 1; } }

        public override int Run(InterpretedFrame frame) {
            frame.Data[frame.StackIndex++] = _value;
            return +1;
        }

        public override string ToString() {
            return "LoadObject(" + (_value ?? "null") + ")";
        }
    }

    internal sealed class LoadCachedObjectInstruction : Instruction {
        private readonly uint _index;

        internal LoadCachedObjectInstruction(uint index) {
            _index = index;
        }

        public override int ProducedStack { get { return 1; } }

        public override int Run(InterpretedFrame frame) {
            frame.Data[frame.StackIndex++] = frame.Interpreter._objects[_index];
            return +1;
        }

        public override string ToDebugString(int instructionIndex, object cookie, Func<int, int> labelIndexer, IList<object> objects) {
            return String.Format("LoadCached({0}: {1})", _index, objects[(int)_index]);
        }
        
        public override string ToString() {
            return "LoadCached(" + _index + ")";
        }
    }

    internal sealed class PopInstruction : Instruction {
        internal static readonly PopInstruction Instance = new PopInstruction();

        private PopInstruction() { }

        public override int ConsumedStack { get { return 1; } }

        public override int Run(InterpretedFrame frame) {
            frame.Pop();
            return +1;
        }

        public override string ToString() {
            return "Pop()";
        }
    }

    // NOTE: Consider caching if used frequently
    internal sealed class PopNInstruction : Instruction {
        private readonly int _n;

        internal PopNInstruction(int n) {
            _n = n;
        }

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

        public override int Run(InterpretedFrame frame) {
            frame.Pop(_n);
            return +1;
        }

        public override string ToString() {
            return "Pop(" + _n + ")";
        }
    }

    internal sealed class DupInstruction : Instruction {
        internal readonly static DupInstruction Instance = new DupInstruction();

        private DupInstruction() { }

        public override int ConsumedStack { get { return 0; } }
        public override int ProducedStack { get { return 1; } }

        public override int Run(InterpretedFrame frame) {
            frame.Data[frame.StackIndex++] = frame.Peek();
            return +1;
        }

        public override string ToString() {
            return "Dup()";
        }
    }
}