/* ****************************************************************************
 *
 * 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;

namespace Microsoft.Scripting.Utils {
    // Compares two ICollection<T>'s using element equality
    internal sealed class ListEqualityComparer<T> : EqualityComparer<ICollection<T>> {
        internal static readonly ListEqualityComparer<T> Instance = new ListEqualityComparer<T>();

        private ListEqualityComparer() { }

        // EqualityComparer<T> handles null and object identity for us
        public override bool Equals(ICollection<T> x, ICollection<T> y) {
            return x.ListEquals(y);
        }

        public override int GetHashCode(ICollection<T> obj) {
            return obj.ListHashCode();
        }
    }
}