/// <summary>
/// Merges the two maps, applying the selector function for keys appearing in both maps.
/// </summary>
/// <param name="other">The other.</param>
/// <param name="collision">
/// The collision resolution function. If null, the values in the other map overwrite the values in this map.
/// </param>
/// <remarks>
/// The merge operation is analogous to a union operation over sets.
///
/// This operation returns all key-value pairs present in either map. If a key is shared between both maps, the collision resolution function is applied to determine the value in the result map.
/// </remarks>
public override ImmSortedMap <TKey, TValue> Merge(IEnumerable <KeyValuePair <TKey, TValue> > other, ValueSelector <TKey, TValue, TValue, TValue> collision = null)
{
other.CheckNotNull("other");
var map = other as ImmSortedMap <TKey, TValue>;
if (map != null && IsCompatibleWith(map))
{
return(Merge(map, collision));
}
int len;
var arr = other.ToArrayFast(out len);
var cmp = Comparers.KeyComparer <KeyValuePair <TKey, TValue>, TKey>(x => x.Key, Comparer);
Array.Sort(arr, 0, len, cmp);
arr.RemoveDuplicatesInSortedArray((a, b) => Comparer.Compare(a.Key, b.Key) == 0, ref len);
var lineage = Lineage.Mutable();
var node = OrderedAvlTree <TKey, TValue> .Node.FromSortedArray(arr, 0, len - 1, Comparer, lineage);
var newRoot = Root.Union(node, collision, lineage);
return(newRoot.WrapMap(Comparer));
}