public static TSource?FirstOrNull <TEnumerable, TEnumerator, TSource>(this TEnumerable source)
where TEnumerable : IReadOnlyCollection <TSource>
where TEnumerator : IEnumerator <TSource>
where TSource : struct
{
if (source == null)
{
ThrowHelper.ThrowArgumentNullException(nameof(source));
}
if (source.Count == 0)
{
return(null);
}
using (var enumerator = Dynamic.GetEnumerator <TEnumerable, TEnumerator, TSource> .Invoke(source))
{
enumerator.MoveNext();
return(enumerator.Current);
}
}
public static bool Contains <TEnumerable, TEnumerator, TSource>(this TEnumerable source, TSource value, IEqualityComparer <TSource> comparer = null)
where TEnumerable : IValueReadOnlyList <TSource, TEnumerator>
where TEnumerator : struct, IValueEnumerator <TSource>
{
if (source == null)
{
ThrowHelper.ThrowArgumentNullException(nameof(source));
}
var count = source.Count();
if (count == 0)
{
return(false);
}
if (comparer is null)
{
for (var index = 0; index < count; index++)
{
if (EqualityComparer <TSource> .Default.Equals(source[index], value))
{
return(true);
}
}
}
else
{
for (var index = 0; index < count; index++)
{
if (comparer.Equals(source[index], value))
{
return(true);
}
}
}
return(false);
}
public static bool Contains <TEnumerable, TEnumerator, TSource>(this TEnumerable source, TSource value, IEqualityComparer <TSource> comparer = null)
where TEnumerable : IValueEnumerable <TSource, TEnumerator>
where TEnumerator : struct, IValueEnumerator <TSource>
{
if (source == null)
{
ThrowHelper.ThrowArgumentNullException(nameof(source));
}
if (comparer is null)
{
using (var enumerator = source.GetValueEnumerator())
{
while (enumerator.TryMoveNext(out var current))
{
if (EqualityComparer <TSource> .Default.Equals(current, value))
{
return(true);
}
}
}
}
else
{
using (var enumerator = source.GetValueEnumerator())
{
while (enumerator.TryMoveNext(out var current))
{
if (comparer.Equals(current, value))
{
return(true);
}
}
}
}
return(false);
}
public static bool Any <TSource>(this Span <TSource> source, Func <TSource, bool> predicate)
{
if (predicate is null)
{
ThrowHelper.ThrowArgumentNullException(nameof(predicate));
}
var length = source.Length;
if (length == 0)
{
return(false);
}
for (var index = 0; index < length; index++)
{
if (predicate(source[index]))
{
return(true);
}
}
return(false);
}
public static TSource Single <TEnumerable, TEnumerator, TSource>(this TEnumerable source)
where TEnumerable : IValueEnumerable <TSource, TEnumerator>
where TEnumerator : struct, IValueEnumerator <TSource>
{
if (source == null)
{
ThrowHelper.ThrowArgumentNullException(nameof(source));
}
using (var enumerator = source.GetValueEnumerator())
{
if (!enumerator.TryMoveNext(out var first))
{
ThrowHelper.ThrowEmptySequence <TSource>();
}
if (enumerator.TryMoveNext())
{
ThrowHelper.ThrowNotSingleSequence <TSource>();
}
return(first);
}
}
