﻿//
// ByteArrayEqualityComparer.cs
//
// Author:
//       Chris Howie <me@chrishowie.com>
//
// Copyright (c) 2015 Chris Howie
//
// 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;
using System.Collections.Generic;
using System.Linq;

namespace Eluant
{
    internal class ByteArrayEqualityComparer : IEqualityComparer<byte[]>
    {
        public static readonly ByteArrayEqualityComparer Instance = new ByteArrayEqualityComparer();

        public ByteArrayEqualityComparer() { }

        #region IEqualityComparer implementation

        public bool Equals(byte[] x, byte[] y)
        {
            if (x == null) {
                return y == null;
            }

            if (y == null || x.Length != y.Length) {
                return false;
            }

            return x.SequenceEqual(y);
        }

        public int GetHashCode(byte[] obj)
        {
            if (obj == null) {
                throw new ArgumentNullException("obj");
            }

            int code = 0;

            foreach (byte b in obj) {
                code = (code >> 29) | (code << 3) ^ b;
            }

            return code;
        }

        #endregion
    }
}

