/// <summary>
/// Creates a key comparer.
/// </summary>
/// <typeparam name="TKey">The type of key objects being compared.</typeparam>
/// <param name="selector">The key selector. May not be <c>null</c>.</param>
/// <param name="keyComparer">The key comparer. Defaults to <c>null</c>. If this is <c>null</c>, the default comparer is used.</param>
/// <param name="allowNulls">A value indicating whether <c>null</c> values are passed to <paramref name="selector"/>. If <c>false</c>, then <c>null</c> values are considered less than any non-<c>null</c> values and are not passed to <paramref name="selector"/>.</param>
/// <returns>A key comparer.</returns>
public IEqualityComparer <T> EquateBy <TKey>(Func <T, TKey> selector, IEqualityComparer <TKey> keyComparer = null, bool allowNulls = false)
{
Contract.Requires(selector != null);
Contract.Ensures(Contract.Result <IEqualityComparer <T> >() != null);
return(EqualityCompare <T> .EquateBy(selector, keyComparer, allowNulls));
}
/// <summary>
/// Gets the default equality comparer for this type.
/// </summary>
public IEqualityComparer <T> Default()
{
Contract.Ensures(Contract.Result <IEqualityComparer <T> >() != null);
return(EqualityCompare <T> .Default());
}
/// <summary>
/// Gets the reference equality comparer for this type.
/// </summary>
public IEqualityComparer <T> Reference()
{
Contract.Ensures(Contract.Result <IEqualityComparer <T> >() != null);
return(EqualityCompare <T> .Reference());
}
/// <summary>
/// Gets the null equality comparer for this type, which evaluates all objects as equivalent.
/// </summary>
public IFullEqualityComparer <T> Null()
{
Contract.Ensures(Contract.Result <IEqualityComparer <T> >() != null);
return(EqualityCompare <T> .Null());
}
