|
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.Collections.Generic;
namespace System.Linq
{
public static partial class Enumerable
{
public static bool Contains<TSource>(this IEnumerable<TSource> source, TSource value) =>
source is ICollection<TSource> collection ? collection.Contains(value) :
Contains(source, value, null);
public static bool Contains<TSource>(this IEnumerable<TSource> source, TSource value, IEqualityComparer<TSource>? comparer)
{
if (source is null)
{
ThrowHelper.ThrowArgumentNullException(ExceptionArgument.source);
}
if (comparer is null)
{
foreach (TSource element in source)
{
if (EqualityComparer<TSource>.Default.Equals(element, value)) // benefits from devirtualization and likely inlining
{
return true;
}
}
}
else
{
foreach (TSource element in source)
{
if (comparer.Equals(element, value))
{
return true;
}
}
}
return false;
}
}
}
|