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();
}
