﻿// AtomicBoolean.cs
//
// Copyright (c) 2008 Jérémie "Garuma" Laval
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//
//

using System;

namespace System.Threading
{
    internal struct AtomicBooleanValue
    {
        int flag;
        const int UnSet = 0;
        const int Set = 1;

        public bool CompareAndExchange(bool expected, bool newVal)
        {
            int newTemp = newVal ? Set : UnSet;
            int expectedTemp = expected ? Set : UnSet;

            return Interlocked.CompareExchange(ref flag, newTemp, expectedTemp) == expectedTemp;
        }

        public static AtomicBooleanValue FromValue(bool value)
        {
            AtomicBooleanValue temp = new AtomicBooleanValue();
            temp.Value = value;

            return temp;
        }

        public bool TrySet()
        {
            return !Exchange(true);
        }

        public bool TryRelaxedSet()
        {
            return flag == UnSet && !Exchange(true);
        }

        public bool Exchange(bool newVal)
        {
            int newTemp = newVal ? Set : UnSet;
            return Interlocked.Exchange(ref flag, newTemp) == Set;
        }

        public bool Value
        {
            get
            {
                return flag == Set;
            }
            set
            {
                Exchange(value);
            }
        }

        public bool Equals(AtomicBooleanValue rhs)
        {
            return this.flag == rhs.flag;
        }

        public override bool Equals(object rhs)
        {
            return rhs is AtomicBooleanValue ? Equals((AtomicBooleanValue)rhs) : false;
        }

        public override int GetHashCode()
        {
            return flag.GetHashCode();
        }

        public static explicit operator bool(AtomicBooleanValue rhs)
        {
            return rhs.Value;
        }

        public static implicit operator AtomicBooleanValue(bool rhs)
        {
            return AtomicBooleanValue.FromValue(rhs);
        }
    }

    internal class AtomicBoolean
    {
        int flag;
        const int UnSet = 0;
        const int Set = 1;

        public bool CompareAndExchange(bool expected, bool newVal)
        {
            int newTemp = newVal ? Set : UnSet;
            int expectedTemp = expected ? Set : UnSet;

            return Interlocked.CompareExchange(ref flag, newTemp, expectedTemp) == expectedTemp;
        }

        public static AtomicBoolean FromValue(bool value)
        {
            AtomicBoolean temp = new AtomicBoolean();
            temp.Value = value;

            return temp;
        }

        public bool TrySet()
        {
            return !Exchange(true);
        }

        public bool TryRelaxedSet()
        {
            return flag == UnSet && !Exchange(true);
        }

        public bool Exchange(bool newVal)
        {
            int newTemp = newVal ? Set : UnSet;
            return Interlocked.Exchange(ref flag, newTemp) == Set;
        }

        public bool Value
        {
            get
            {
                return flag == Set;
            }
            set
            {
                Exchange(value);
            }
        }

        public bool Equals(AtomicBoolean rhs)
        {
            return this.flag == rhs.flag;
        }

        public override bool Equals(object rhs)
        {
            return rhs is AtomicBoolean ? Equals((AtomicBoolean)rhs) : false;
        }

        public override int GetHashCode()
        {
            return flag.GetHashCode();
        }

        public static explicit operator bool(AtomicBoolean rhs)
        {
            return rhs.Value;
        }

        public static implicit operator AtomicBoolean(bool rhs)
        {
            return AtomicBoolean.FromValue(rhs);
        }
    }
}
