public TElement Last(Func <TElement, bool> predicate)
{
CachingComparer <TElement> comparer = GetComparer();
using (IEnumerator <TElement> e = source.GetEnumerator())
{
TElement value;
do
{
if (!e.MoveNext())
{
throw Error.NoMatch();
}
value = e.Current;
} while (!predicate(value));
comparer.SetElement(value);
while (e.MoveNext())
{
TElement x = e.Current;
if (predicate(x) && comparer.Compare(x, false) >= 0)
{
value = x;
}
}
return(value);
}
}
public static TSource First <TSource>(this IEnumerable <TSource> source, Func <TSource, bool> predicate)
{
if (source == null)
{
throw Error.ArgumentNull("source");
}
if (predicate == null)
{
throw Error.ArgumentNull("predicate");
}
OrderedEnumerable <TSource> ordered = source as OrderedEnumerable <TSource>;
if (ordered != null)
{
return(ordered.First(predicate));
}
foreach (TSource element in source)
{
if (predicate(element))
{
return(element);
}
}
throw Error.NoMatch();
}
public static TSource Single <TSource>(this IEnumerable <TSource> source, Func <TSource, bool> predicate)
{
if (source == null)
{
throw Error.ArgumentNull(nameof(source));
}
if (predicate == null)
{
throw Error.ArgumentNull(nameof(predicate));
}
using (IEnumerator <TSource> e = source.GetEnumerator())
{
while (e.MoveNext())
{
TSource result = e.Current;
if (predicate(result))
{
while (e.MoveNext())
{
if (predicate(e.Current))
{
throw Error.MoreThanOneMatch();
}
}
return(result);
}
}
}
throw Error.NoMatch();
}
public static TSource Last <TSource>(this IEnumerable <TSource> source, Func <TSource, bool> predicate)
{
if (source == null)
{
throw Error.ArgumentNull(nameof(source));
}
if (predicate == null)
{
throw Error.ArgumentNull(nameof(predicate));
}
OrderedEnumerable <TSource> ordered = source as OrderedEnumerable <TSource>;
if (ordered != null)
{
return(ordered.Last(predicate));
}
IList <TSource> list = source as IList <TSource>;
if (list != null)
{
for (int i = list.Count - 1; i >= 0; --i)
{
TSource result = list[i];
if (predicate(result))
{
return(result);
}
}
}
else
{
using (IEnumerator <TSource> e = source.GetEnumerator())
{
while (e.MoveNext())
{
TSource result = e.Current;
if (predicate(result))
{
while (e.MoveNext())
{
TSource element = e.Current;
if (predicate(element))
{
result = element;
}
}
return(result);
}
}
}
}
throw Error.NoMatch();
}
public static TSource First <TSource>(this IEnumerable <TSource> source, Func <TSource, bool> predicate)
{
TSource first = source.TryGetFirst(predicate, out bool found);
if (!found)
{
throw Error.NoMatch();
}
return(first);
}
public static TSource Last <TSource>(this IEnumerable <TSource> source, Func <TSource, bool> predicate)
{
bool found;
TSource last = source.TryGetLast(predicate, out found);
if (!found)
{
throw Error.NoMatch();
}
return(last);
}