private static <K, V> ImmutableSetMultimap<K, V> copyOf(
Multimap<? extends K, ? extends V> multimap, Comparator<? super V> valueComparator) {
Preconditions.checkNotNull(multimap); // eager for GWT
if (multimap.isEmpty() && valueComparator == null) {
return of();
}
if (multimap instanceof ImmutableSetMultimap) {
@SuppressWarnings("unchecked")
// safe since multimap is not writable
ImmutableSetMultimap<K, V> kvMultimap = (ImmutableSetMultimap<K, V>) multimap;
if (!kvMultimap.isPartialView()) {
return kvMultimap;
}
}
ImmutableMap.Builder<K, ImmutableSet<V>> builder = ImmutableMap.builder();
int size = 0;
for (Map.Entry<? extends K, ? extends Collection<? extends V>> entry :
multimap.asMap().entrySet()) {
K key = entry.getKey();
Collection<? extends V> values = entry.getValue();
ImmutableSet<V> set =
(valueComparator == null)
? ImmutableSet.copyOf(values)
: ImmutableSortedSet.copyOf(valueComparator, values);
if (!set.isEmpty()) {
builder.put(key, set);
size += set.size();
}
}
return new ImmutableSetMultimap<K, V>(builder.build(), size, valueComparator);
}
ImmutableSetMultimap(
ImmutableMap<K, ImmutableSet<V>> map, int size, Comparator<? super V> valueComparator) {
super(map, size);
this.emptySet =
(valueComparator == null) ? null : ImmutableSortedSet.<V>emptySet(valueComparator);
}
