// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
#nullable disable
 
using System.Collections.Generic;
 
namespace Microsoft.CodeAnalysis.CSharp.Simplification.Simplifiers
{
    internal partial class ExpressionSimplifier
    {
        /// <summary>
        /// Compares symbols by their original definition.
        /// </summary>
        private sealed class CandidateSymbolEqualityComparer : IEqualityComparer<ISymbol>
        {
            public static CandidateSymbolEqualityComparer Instance { get; } = new CandidateSymbolEqualityComparer();
 
            private CandidateSymbolEqualityComparer()
            {
            }
 
            public bool Equals(ISymbol x, ISymbol y)
            {
                if (x is null || y is null)
                {
                    return x == y;
                }
 
                return x.OriginalDefinition.Equals(y.OriginalDefinition);
            }
 
            public int GetHashCode(ISymbol obj)
                => obj?.OriginalDefinition.GetHashCode() ?? 0;
        }
    }
}