/**
* Returns an immutable bimap containing the same entries as {@code map}. If {@code map} somehow
* contains entries with duplicate keys (for example, if it is a {@code SortedMap} whose
* comparator is not <i>consistent with equals</i>), the results of this method are undefined.
*
* <p>Despite the method name, this method attempts to avoid actually copying the data when it is
* safe to do so. The exact circumstances under which a copy will or will not be performed are
* undocumented and subject to change.
*
* @throws IllegalArgumentException if two keys have the same value
* @throws NullPointerException if any key or value in {@code map} is null
*/
public static <K, V> ImmutableBiMap<K, V> copyOf(Map<? extends K, ? extends V> map) {
if (map instanceof ImmutableBiMap) {
@SuppressWarnings("unchecked") // safe since map is not writable
ImmutableBiMap<K, V> bimap = (ImmutableBiMap<K, V>) map;
// TODO(lowasser): if we need to make a copy of a BiMap because the
// forward map is a view, don't make a copy of the non-view delegate map
if (!bimap.isPartialView()) {
return bimap;
}
}
return copyOf(map.entrySet());
}
