/// <summary>
/// Implementation Notes:
/// Since resizes are relatively expensive (require rehashing), this attempts to minimize
/// the need to resize by setting the initial capacity based on size of collection.
/// </summary>
/// <param name="collection"></param>
/// <param name="comparer"></param>
public HashSet(IEnumerable <T> collection, IEqualityComparer <T> comparer)
: this(comparer) {
if (collection == null)
{
throw new ArgumentNullException("collection");
}
// to avoid excess resizes, first set size based on collection's count. Collection
// may contain duplicates, so call TrimExcess if resulting hashset is larger than
// threshold
int suggestedCapacity = 0;
ICollection <T> coll = collection as ICollection <T>;
if (coll != null)
{
suggestedCapacity = coll.Count;
}
Initialize(suggestedCapacity);
this.UnionWith(collection);
if ((m_count == 0 && m_slots.Length > HashHelpers.GetMinPrime()) ||
(m_count > 0 && m_slots.Length / m_count > ShrinkThreshold))
{
TrimExcess();
}
}
/// <summary>
/// Initializes a new instance of the <see cref="T:System.Collections.Generic.HashSet`1" /> class that uses the specified equality comparer for the set type,
/// contains elements copied from the specified collection,
/// and has sufficient capacity to accommodate the number of elements copied.
/// </summary>
/// <param name="collection">The collection whose elements are copied to the new set.</param>
/// <param name="comparer">The <see cref="T:System.Collections.Generic.IEqualityComparer`1" /> implementation to use when comparing values in the set, or null to use the default <see cref="T:System.Collections.Generic.EqualityComparer`1" /> implementation for the set type.</param>
/// <exception cref="T:System.ArgumentNullException">collection is null.</exception>
public HashSet(IEnumerable <T> collection, IEqualityComparer <T> comparer) : this(comparer)
{
if (collection == null)
{
throw new ArgumentNullException("collection");
}
int capacity = 0;
ICollection <T> is2 = collection as ICollection <T>;
if (is2 != null)
{
capacity = is2.Count;
}
this.Initialize(capacity);
this.UnionWith(collection);
if (((this.m_count == 0) && (this.m_slots.Length > HashHelpers.GetMinPrime())) || ((this.m_count > 0) && ((this.m_slots.Length / this.m_count) > 3)))
{
this.TrimExcess();
}
}
public HashSet(IEnumerable <T> collection, IEqualityComparer <T> comparer)
: this(comparer)
{
if (collection == null)
{
throw new ArgumentNullException("collection");
}
int suggestedCapacity = 0;
ICollection <T> coll = collection as ICollection <T>;
if (coll != null)
{
suggestedCapacity = coll.Count;
}
Initialize(suggestedCapacity);
this.UnionWith(collection);
if ((_count == 0 && _slots.Length > HashHelpers.GetMinPrime()) ||
(_count > 0 && _slots.Length / _count > ShrinkThreshold))
{
TrimExcess();
}
}
