queue.go

package main

// FIFO queue

type Queue struct {
	data  []*Line
	front int
	rear  int
	size  int
}

func NewQueue(size int) *Queue {
	return &Queue{
		make([]*Line, size), size - 1, size, 0,
	}
}

func (q *Queue) Len() int {
	return len(q.data)
}

func (q *Queue) Cap() int {
	return cap(q.data)
}

func (q *Queue) IsEmpty() bool {
	return q.size == 0
}

func (q *Queue) Enqueue(line *Line) {
	if (q.rear - 1) >= 0 {
		q.data[q.rear-1] = line
		q.rear -= 1
		q.size += 1
	} else {
		panic("ERROR :: We need to allocate more Queue space")
	}
}

func (q *Queue) Dequeue() *Line {
	if q.rear <= q.front {
		deleted := q.data[q.front]
		copy(q.data[q.Len()-q.size+1:], q.data[q.Len()-q.size:q.Len()-1])
		q.data[q.Len()-q.size] = nil
		q.size -= 1
		q.rear += 1
		return deleted
	}
	return nil
}