@Override
public <C> Map<C, Array<T>> groupBy(Function<? super T, ? extends C> classifier) {
return foldLeft(
HashMap.empty(),
(map, t) -> {
final C key = classifier.apply(t);
final Array<T> values = map.get(key).map(ts -> ts.append(t)).getOrElse(of(t));
return map.put(key, values);
});
}
@Override
public <U> Array<T> sortBy(
Comparator<? super U> comparator, Function<? super T, ? extends U> mapper) {
final Function<? super T, ? extends U> domain = Function1.of(mapper::apply).memoized();
return toJavaStream()
.sorted((e1, e2) -> comparator.compare(domain.apply(e1), domain.apply(e2)))
.collect(collector());
}
@Override
public <U> Array<U> map(Function<? super T, ? extends U> mapper) {
Objects.requireNonNull(mapper, "mapper is null");
final Object[] arr = new Object[length()];
for (int i = 0; i < length(); i++) {
arr[i] = mapper.apply(get(i));
}
return wrap(arr);
}
@Override
public <U> Array<T> distinctBy(Function<? super T, ? extends U> keyExtractor) {
Objects.requireNonNull(keyExtractor, "keyExtractor is null");
final java.util.Set<U> seen = new java.util.HashSet<>();
return filter(t -> seen.add(keyExtractor.apply(t)));
}
@Override
public Array<T> distinct() {
return distinctBy(Function.identity());
}
@Override
public Array<Array<T>> combinations() {
return rangeClosed(0, length()).map(this::combinations).flatMap(Function.identity());
}