package ucontainer

// Set is a set of unique items, built on top of map.
type Set[T comparable] map[T] struct { }

// NewSet creates a new set that contains all specified items.
func NewSet[T comparable] (items ...T) Set[T] {
	set := make(Set[T])
	for _, item := range items {
		set.Add(item)
	}
	return set
}

// Empty returns true if there are no items in the set.
func (set Set[T]) Empty () bool {
	return set == nil || len(set) == 0
}

// Has returns true if the set contains item.
func (set Set[T]) Has (item T) bool {
	if set == nil {
		return false
	}
	_, ok := set[item]
	return ok
}

// Add adds an item to the set.
func (set Set[T]) Add (item T) {
	set[item] = struct { } { }
}

// Pop removes the first accessible item from the set and returns it.
func (set Set[T]) Pop () (item T) {
	for item := range set {
		delete(set, item)
		return item
	}
	return
}