Files
Umbraco-CMS/src/Umbraco.Core/DelegateEqualityComparer.cs
Nikolaj Brask-Nielsen 6d48091328 docs: XML warnings (#14663)
* chore: Fix XML warnings

* docs: Fix XML warnings

* docs: Fix XML in resource designer

* docs: Fix XML warnings

* Revert "docs: Fix XML in resource designer"

This reverts commit 8ea61c51ac161e1853ae080db7fe1b4d4cb4d2be.
2023-09-06 20:08:17 +02:00

55 lines
2.0 KiB
C#

namespace Umbraco.Cms.Core;
/// <summary>
/// A custom equality comparer that excepts a delegate to do the comparison operation
/// </summary>
/// <typeparam name="T"></typeparam>
public class DelegateEqualityComparer<T> : IEqualityComparer<T>
{
private readonly Func<T?, T?, bool> _equals;
private readonly Func<T, int> _getHashcode;
#region Implementation of IEqualityComparer<in T>
public DelegateEqualityComparer(Func<T?, T?, bool> equals, Func<T, int> getHashcode)
{
_getHashcode = getHashcode;
_equals = equals;
}
public static DelegateEqualityComparer<T> CompareMember<TMember>(Func<T?, TMember> memberExpression)
where TMember : IEquatable<TMember> =>
new DelegateEqualityComparer<T>(
(x, y) => memberExpression.Invoke(x).Equals(memberExpression.Invoke(y)),
x =>
{
TMember invoked = memberExpression.Invoke(x);
return !ReferenceEquals(invoked, default(TMember)) ? invoked.GetHashCode() : 0;
});
/// <summary>
/// Determines whether the specified objects are equal.
/// </summary>
/// <returns>
/// true if the specified objects are equal; otherwise, false.
/// </returns>
/// <param name="x">The first object of type <typeparamref name="T"/> to compare.</param>
/// <param name="y">The second object of type <typeparamref name="T"/> to compare.</param>
public bool Equals(T? x, T? y) => _equals.Invoke(x, y);
/// <summary>
/// Returns a hash code for the specified object.
/// </summary>
/// <returns>
/// A hash code for the specified object.
/// </returns>
/// <param name="obj">The <see cref="T:System.Object" /> for which a hash code is to be returned.</param>
/// <exception cref="T:System.ArgumentNullException">
/// The type of <paramref name="obj" /> is a reference type and
/// <paramref name="obj" /> is null.
/// </exception>
public int GetHashCode(T obj) => _getHashcode.Invoke(obj);
#endregion
}