/// <summary>
/// Removes elements in the specified collection for which the specified predicate
/// returns true in the range [first, last).
/// </summary>
/// <typeparam name="T">The type of elements in the collection.</typeparam>
/// <param name="source">The collection to remove elements from.</param>
/// <param name="first">The index in the <paramref name="source"/> collection specifying
/// the beginning of the elements range to perform removing at.</param>
/// <param name="last">The index in the <paramref name="source"/> collection specifying
/// the end of the elements range to perform removing at.</param>
/// <param name="predicate">The predicate to be used for finding elements
/// to be removed.</param>
/// <returns>The index in the <paramref name="source"/> collection such that all elements
/// in range [0, index) do not satisfy the <paramref name="predicate"/>.</returns>
/// <exception cref="ArgumentNullException"><paramref name="source"/> or
/// <paramref name="predicate"/> is a null reference.</exception>
/// <exception cref="ArgumentOutOfRangeException"><paramref name="first"/> or
/// <paramref name="last"/> is not in [0, <paramref name="source"/>.Count] range or
/// <paramref name="first"/> is greater than <paramref name="last"/>.</exception>
/// <remarks>The relative order of element that are not removed is the same as their
/// relative order before removal of other elements.</remarks>
public static int RemoveIf <T>(
this IList <T> source,
int first,
int last,
Func <T, bool> predicate)
{
CodeContract.RequiresNotNull("source", source);
CodeContract.RequiresValueInRange("first", first, 0, source.Count);
CodeContract.RequiresValueInRange("last", last, 0, source.Count);
CodeContract.RequiresLessThanOrEqual("first", first, last);
CodeContract.RequiresNotNull("predicate", predicate);
var next = first;
for (; first != last; ++first)
{
if (!predicate(source[first]))
{
var tmp = source[next];
source[next] = source[first];
source[first] = tmp;
++next;
}
}
return(next);
}