// 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.
 
using System;
using System.Collections.Generic;
 
namespace Microsoft.CodeAnalysis.Editor.EditorConfigSettings.Extensions;
 
internal static class EnumerableExtensions
{
    public static IEnumerable<TSource> DistinctBy<TSource, TKey>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector)
    {
        var seenKeys = new HashSet<TKey>();
        foreach (var element in source)
        {
            if (seenKeys.Add(keySelector(element)))
            {
                yield return element;
            }
        }
    }
}