@Override
public Vector<Vector<T>> permutations() {
if (isEmpty()) {
return Vector.empty();
} else {
final Vector<T> tail = tail();
if (tail.isEmpty()) {
return Vector.of(this);
} else {
final Vector<Vector<T>> zero = empty();
// TODO: IntelliJ IDEA 14.1.1 needs a redundant cast here, jdk 1.8.0_40 compiles fine
return distinct()
.foldLeft(
zero,
(xs, x) ->
xs.appendAll(
remove(x)
.permutations()
.map((Function<Vector<T>, Vector<T>>) l -> l.prepend(x))));
}
}
}
@Override
public boolean equals(Object o) {
if (o == this) {
return true;
} else if (o instanceof Vector) {
Vector<?> vector1 = this;
Vector<?> vector2 = (Vector<?>) o;
while (!vector1.isEmpty() && !vector2.isEmpty()) {
final boolean isEqual = Objects.equals(vector1.head(), vector2.head());
if (!isEqual) {
return false;
}
vector1 = vector1.tail();
vector2 = vector2.tail();
}
return vector1.isEmpty() && vector2.isEmpty();
} else {
return false;
}
}
