/// <summary>
/// Removes a given value from the values associated with a key. If the
/// last value is removed from a key, the key is removed also.
/// </summary>
/// <param name="key">A key to remove a value from.</param>
/// <param name="value">The value to remove.</param>
/// <returns>True if <paramref name="value"/> was associated with <paramref name="key"/> (and was
/// therefore removed). False if <paramref name="value"/> was not associated with <paramref name="key"/>.</returns>
public sealed override bool Remove(TKey key, TValue value)
{
KeyAndValues keyValues = new KeyAndValues(key);
KeyAndValues existing;
if (hash.Find(keyValues, false, out existing))
{
// There is an item in the hash table equal to this key. Find the value.
int existingCount = existing.Count;
int valueHash = CollectionUtil.GetHashCode(value, valueEqualityComparer);
int indexFound = -1;
for (int i = 0; i < existingCount; ++i)
{
if (CollectionUtil.GetHashCode(existing.Values[i], valueEqualityComparer) == valueHash &&
valueEqualityComparer.Equals(existing.Values[i], value))
{
// Found an equal existing value
indexFound = i;
}
}
if (existingCount == 1)
{
// Removing the last value. Remove the key.
hash.Delete(existing, out keyValues);
return(true);
}
else if (indexFound >= 0)
{
// Found a value. Remove it.
if (indexFound < existingCount - 1)
{
Array.Copy(existing.Values, indexFound + 1, existing.Values, indexFound, existingCount - indexFound - 1);
}
existing.Count = existingCount - 1;
// Update the hash.
hash.Find(existing, true, out keyValues);
return(true);
}
else
{
// Value was not found.
return(false);
}
}
else
{
return(false); // key not found.
}
}
/// <summary>
/// <para>Adds a new value to be associated with a key. If duplicate values are permitted, this
/// method always adds a new key-value pair to the dictionary.</para>
/// <para>If duplicate values are not permitted, and <paramref name="key"/> already has a value
/// equal to <paramref name="value"/> associated with it, then that value is replaced with <paramref name="value"/>,
/// and the number of values associate with <paramref name="key"/> is unchanged.</para>
/// </summary>
/// <param name="key">The key to associate with.</param>
/// <param name="value">The value to associated with <paramref name="key"/>.</param>
public sealed override void Add(TKey key, TValue value)
{
KeyAndValues keyValues = new KeyAndValues(key);
KeyAndValues existing;
if (hash.Find(keyValues, false, out existing))
{
// There already is an item in the hash table equal to this key. Add the new value,
// taking into account duplicates if needed.
int existingCount = existing.Count;
if (!allowDuplicateValues)
{
int valueHash = CollectionUtil.GetHashCode(value, valueEqualityComparer);
for (int i = 0; i < existingCount; ++i)
{
if (CollectionUtil.GetHashCode(existing.Values[i], valueEqualityComparer) == valueHash &&
valueEqualityComparer.Equals(existing.Values[i], value))
{
// Found an equal existing value. Replace it and we're done.
existing.Values[i] = value;
return;
}
}
}
// Add a new value to an existing key.
if (existingCount == existing.Values.Length)
{
// Grow the array to make room.
TValue[] newValues = new TValue[existingCount * 2];
Array.Copy(existing.Values, newValues, existingCount);
existing.Values = newValues;
}
existing.Values[existingCount] = value;
existing.Count = existingCount + 1;
// Update the hash table.
hash.Find(existing, true, out keyValues);
return;
}
else
{
// No item with this key. Add it.
keyValues.Count = 1;
keyValues.Values = new TValue[1] {
value
};
hash.Insert(keyValues, true, out existing);
return;
}
}
/// <summary>
/// Gets the full hash code for an item.
/// </summary>
/// <param name="item">Item to get hash code for.</param>
/// <returns>The full hash code. It is never zero.</returns>
private int GetFullHash(T item)
{
uint hash;
hash = (uint)CollectionUtil.GetHashCode(item, equalityComparer);
// The .NET framework tends to produce pretty bad hash codes.
// Scramble them up to be much more random!
hash += ~(hash << 15);
hash ^= (hash >> 10);
hash += (hash << 3);
hash ^= (hash >> 6);
hash += ~(hash << 11);
hash ^= (hash >> 16);
hash &= 0x7FFFFFFF;
if (hash == 0)
{
hash = 0x7FFFFFFF; // Make sure it isn't zero.
}
return((int)hash);
}
/// <summary>
/// Checks to see if <paramref name="value"/> is associated with <paramref name="key"/>
/// in the dictionary.
/// </summary>
/// <param name="key">The key to check.</param>
/// <param name="value">The value to check.</param>
/// <returns>True if <paramref name="value"/> is associated with <paramref name="key"/>.</returns>
public sealed override bool Contains(TKey key, TValue value)
{
KeyAndValues find = new KeyAndValues(key);
KeyAndValues item;
if (hash.Find(find, false, out item))
{
int existingCount = item.Count;
int valueHash = CollectionUtil.GetHashCode(value, valueEqualityComparer);
for (int i = 0; i < existingCount; ++i)
{
if (CollectionUtil.GetHashCode(item.Values[i], valueEqualityComparer) == valueHash &&
valueEqualityComparer.Equals(item.Values[i], value))
{
// Found an equal existing value.
return(true);
}
}
}
return(false);
}
public int GetHashCode(KeyAndValues obj)
{
return(CollectionUtil.GetHashCode(obj.Key, keyEqualityComparer));
}
public int GetHashCode(KeyValuePair <TKey, TValue> obj)
{
return(CollectionUtil.GetHashCode(obj.Key, keyEqualityComparer));
}
