public static TSource First <TSource>(IEnumerable <TSource> source)
{
if (source == null)
{
throw ThrowHelper.ArgumentNull("source");
}
IList <TSource> list = source as IList <TSource>;
if (list == null)
{
using (IEnumerator <TSource> enumerator = source.GetEnumerator())
{
if (!enumerator.MoveNext())
{
throw ThrowHelper.NoElements();
}
else
{
return(enumerator.Current);
}
}
}
else if (list.Count > 0)
{
return(list[0]);
}
throw ThrowHelper.NoElements();
}
public static List <TSource> ToList <TSource>(IEnumerable <TSource> source)
{
if (source == null)
{
throw ThrowHelper.ArgumentNull("source");
}
return(new List <TSource>(source));
}
public static IEnumerable <TSource> Skip <TSource>(IEnumerable <TSource> source, int count)
{
if (source == null)
{
throw ThrowHelper.ArgumentNull("source");
}
return(Enumerable.SkipIterator <TSource>(source, count));
}
public static IEnumerable <TResult> Select <TSource, TResult>(IEnumerable <TSource> source, Func <TSource, int, TResult> selector)
{
if (source == null)
{
throw ThrowHelper.ArgumentNull("source");
}
if (selector == null)
{
throw ThrowHelper.ArgumentNull("selector");
}
return(Enumerable.SelectIterator <TSource, TResult>(source, selector));
}
public static TSource[] ToArray <TSource>(IEnumerable <TSource> source)
{
if (source == null)
{
throw ThrowHelper.ArgumentNull("source");
}
TSource[] array = source as TSource[];
if (array != null)
{
return(array);
}
return(new List <TSource>(source).ToArray());
}
public static IEnumerable <TResult> Select <TSource, TResult>(IEnumerable <TSource> source, Func <TSource, TResult> selector)
{
if (source == null)
{
throw ThrowHelper.ArgumentNull("source");
}
if (selector == null)
{
throw ThrowHelper.ArgumentNull("selector");
}
foreach (TSource item in source)
{
yield return(selector(item));
}
}
public static bool Any <TSource>(IEnumerable <TSource> source)
{
if (source == null)
{
throw ThrowHelper.ArgumentNull("source");
}
using (IEnumerator <TSource> enumerator = source.GetEnumerator())
{
if (!enumerator.MoveNext())
{
return(false);
}
else
{
return(true);
}
}
}
public static IEnumerable <TSource> Where <TSource>(IEnumerable <TSource> source, Func <TSource, bool> predicate)
{
if (source == null)
{
throw ThrowHelper.ArgumentNull("source");
}
if (predicate == null)
{
throw ThrowHelper.ArgumentNull("predicate");
}
foreach (TSource item in source)
{
if (predicate(item))
{
yield return(item);
}
}
}
public static TSource FirstOrDefault <TSource>(IEnumerable <TSource> source, Func <TSource, bool> predicate)
{
if (source == null)
{
throw ThrowHelper.ArgumentNull("source");
}
if (predicate == null)
{
throw ThrowHelper.ArgumentNull("predicate");
}
foreach (TSource item in source)
{
if (predicate(item))
{
return(item);
}
}
return(default(TSource));
}
public static Dictionary <TKey, TElement> ToDictionary <TSource, TKey, TElement>(IEnumerable <TSource> source, Func <TSource, TKey> keySelector, Func <TSource, TElement> elementSelector, IEqualityComparer <TKey> comparer)
{
if (source == null)
{
throw ThrowHelper.ArgumentNull("source");
}
if (keySelector == null)
{
throw ThrowHelper.ArgumentNull("keySelector");
}
if (elementSelector == null)
{
throw ThrowHelper.ArgumentNull("elementSelector");
}
Dictionary <TKey, TElement> tKeys = new Dictionary <TKey, TElement>(comparer);
foreach (TSource tSource in source)
{
tKeys.Add(keySelector(tSource), elementSelector(tSource));
}
return(tKeys);
}
