/// <summary>
/// Creates a <see cref="T:System.Collections.Generic.List`1" /> of specified capacity from an <see cref="T:System.Collections.Generic.IEnumerable`1"/>.
/// </summary>
/// <param name="source">The <see cref="T:System.Collections.Generic.IEnumerable`1" /> to create a <see cref="T:System.Collections.Generic.List`1" /> from.</param>
/// <param name="capacity">The number of elements that the new list can initially store.</param>
/// <typeparam name="TItem">The type of the elements of <paramref name="source" />.</typeparam>
/// <returns>A <see cref="T:System.Collections.Generic.List`1" /> that contains elements from the input sequence.</returns>
public static List <TItem> ToList <TItem>(this IEnumerable <TItem> source, int capacity)
{
ArgumentValidator.EnsureArgumentIsGreaterThanOrEqual(capacity, 0, "capacity");
var result = new List <TItem>(capacity);
result.AddRange(source);
return(result);
}
/// <summary>
/// Same as <code>sequence.ExtendWithDefaultsTo(length).Take(length).ToArray()</code>,
/// but with a single allocation (of a resulting array).
/// </summary>
/// <param name="sequence">Source sequence.</param>
/// <param name="length">The length of the resulting array.</param>
/// <typeparam name="T">The sequence element type.</typeparam>
/// <returns>The resulting array.</returns>
/// <exception cref="ArgumentException"><paramref name="length"/> is negative.</exception>
public static T[] ToArray <T>(this IEnumerable <T> sequence, int length)
{
ArgumentValidator.EnsureArgumentIsGreaterThanOrEqual(length, 0, nameof(length));
if (length == 0)
{
return(Array.Empty <T>());
}
var result = new T[length];
using (var e = sequence.GetEnumerator()) {
for (var i = 0; i < length && e.MoveNext(); i++)
{
result[i] = e.Current;
}
}
return(result);
}