Implements queues, LinkedListQueue and ArrayQueue

queues/arrayqueue/arrayqueue.go

@@ -0,0 +1,88 @@
+// Copyright (c) 2021, Aryan Ahadinia. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package arrayqueue implements a queue backed by array list.
+//
+// Structure is not thread safe.
+//
+// Reference: https://en.wikipedia.org/wiki/Queue_(abstract_data_type)
+package arrayqueue
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/emirpasic/gods/lists/arraylist"
+	"github.com/emirpasic/gods/queues"
+)
+
+// Assert Queue implementation
+var _ queues.Queue = (*Queue)(nil)
+
+// Queue holds elements in an array-list
+type Queue struct {
+	list *arraylist.List
+}
+
+// New instantiates a new empty queue
+func New() *Queue {
+	return &Queue{list: arraylist.New()}
+}
+
+// Enqueue adds a value to the end of the queue
+func (queue *Queue) Enqueue(value interface{}) {
+	queue.list.Add(value)
+}
+
+// Dequeue removes first element of the queue and returns it, or nil if queue is empty.
+// Second return parameter is true, unless the queue was empty and there was nothing to dequeue.
+func (queue *Queue) Dequeue() (value interface{}, ok bool) {
+	value, ok = queue.list.Get(0)
+	if ok {
+		queue.list.Remove(0)
+	}
+	return
+}
+
+// Peek returns first element of the queue without removing it, or nil if queue is empty.
+// Second return parameter is true, unless the queue was empty and there was nothing to peek.
+func (queue *Queue) Peek() (value interface{}, ok bool) {
+	return queue.list.Get(0)
+}
+
+// Empty returns true if queue does not contain any elements.
+func (queue *Queue) Empty() bool {
+	return queue.list.Empty()
+}
+
+// Size returns number of elements within the queue.
+func (queue *Queue) Size() int {
+	return queue.list.Size()
+}
+
+// Clear removes all elements from the queue.
+func (queue *Queue) Clear() {
+	queue.list.Clear()
+}
+
+// Values returns all elements in the queue (FIFO order).
+func (queue *Queue) Values() []interface{} {
+	return queue.list.Values()
+}
+
+// String returns a string representation of container
+func (queue *Queue) String() string {
+	str := "ArrayQueue\n"
+	values := []string{}
+	for _, value := range queue.list.Values() {
+		values = append(values, fmt.Sprintf("%v", value))
+	}
+	str += strings.Join(values, ", ")
+	return str
+}
+
+// Check that the index is within bounds of the list
+func (queue *Queue) withinRange(index int) bool {
+	return index >= 0 && index < queue.list.Size()
+}