Method Enqueue

topics/go/algorithms/data/queue/queue.go:40–71

Enqueue inserts data into the queue if there is available capacity.

(data *Data)

// Enqueue inserts data into the queue if there
// is available capacity.
func (q *Queue) Enqueue(data *Data) error {

	// If the front of the queue is right behind the end or
	// if the front is at the end of the capacity and the end
	// is at the beginning of the capacity, the queue is full.
	//  F  E  - Enqueue (Full) |  E        F - Enqueue (Full)
	// [A][B][C]               | [A][B][C]
	if q.front+1 == q.end ||
		q.front == len(q.data) && q.end == 0 {
		return errors.New("queue at capacity")
	}

	switch {
	case q.front == len(q.data):

		// If we are at the end of the capacity, then
		// circle back to the beginning of the capacity by
		// moving the front pointer to the beginning.
		q.front = 0
		q.data[q.front] = data
	default:

		// Add the data to the current front position
		// and then move the front pointer.
		q.data[q.front] = data
		q.front++
	}

	q.Count++

	return nil
}

// Dequeue removes data into the queue if data exists.
func (q *Queue) Dequeue() (*Data, error) {