feat: add deque, tests, and docs

README.md

@@ -1,2 +1,23 @@
 # deque
 Library of generic deque data structure for Go.
+
+## Install
+
+```Go
+$ go get github.com/golang-ds/deque
+```
+
+## Deque Usage
+
+### Import
+
+```Go
+import "github.com/golang-ds/deque"
+```
+
+### Use
+
+```Go
+d := deque.New[int]()
+d.AddFirst(1)
+```

deque.go

@@ -0,0 +1,67 @@
+package deque
+
+import "github.com/golang-ds/linkedlist/doubly"
+
+type Deque[T any] struct {
+	data doubly.LinkedList[T]
+}
+
+// New constructs and returns an empty deque.
+// time-complexity: O(1)
+func New[T any]() Deque[T] {
+	return Deque[T]{data: doubly.New[T]()}
+}
+
+// Size returns the number of the elements in the deque.
+// time-complexity: O(1)
+func (d *Deque[T]) Size() int {
+	return d.data.Size
+}
+
+// IsEmpty returns true if the deque doesn't have any elements.
+// time-complexity: O(1)
+func (d *Deque[T]) IsEmpty() bool {
+	return d.Size() == 0
+}
+
+// First returns the first element in the deque. It returns false if the deque is empty.
+// time-complexity: O(1)
+func (d *Deque[T]) First() (T, bool) {
+	return d.data.First()
+}
+
+// Last returns the last element in the deque. It returns false if the deque is empty.
+// time-complexity: O(1)
+func (d *Deque[T]) Last() (T, bool) {
+	return d.data.Last()
+}
+
+// AddFirst adds an element to the front of the deque.
+// time-complexity: O(1)
+func (d *Deque[T]) AddFirst(data T) {
+	d.data.AddFirst(data)
+}
+
+// AddLast adds an element to the end of the deque.
+// time-complexity: O(1)
+func (d *Deque[T]) AddLast(data T) {
+	d.data.AddLast(data)
+}
+
+// RemoveFirst removes the first element from the deque and returns it. It returns false if the deque is empty.
+// time-complexity: O(1)
+func (d *Deque[T]) RemoveFirst() (T, bool) {
+	return d.data.RemoveFirst()
+}
+
+// RemoveLast removes the last element from the deque and returns it. It returns false if the deque is empty.
+// time-complexity: O(1)
+func (d *Deque[T]) RemoveLast() (T, bool) {
+	return d.data.RemoveLast()
+}
+
+// String returns the string representation of the deque.
+// time-complexity: O(n)
+func (d *Deque[T]) String() string {
+	return d.data.String()
+}

deque_test.go

@@ -0,0 +1,164 @@
+package deque
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSize(t *testing.T) {
+	deque := New[int]()
+
+	s := deque.Size()
+	assert.Equal(t, 0, s)
+
+	deque.AddFirst(1)
+	deque.AddFirst(2)
+	deque.AddFirst(3)
+	deque.AddFirst(4)
+
+	s = deque.Size()
+	assert.Equal(t, 4, s)
+}
+
+func TestIsEmpty(t *testing.T) {
+	deque := New[int]()
+
+	assert.True(t, deque.IsEmpty())
+
+	deque.AddFirst(1)
+	deque.AddFirst(2)
+	deque.AddFirst(3)
+	deque.AddFirst(4)
+
+	assert.False(t, deque.IsEmpty())
+}
+
+func TestFirst(t *testing.T) {
+	deque := New[int]()
+
+	f, ok := deque.First()
+	assert.False(t, ok)
+	assert.Equal(t, 0, f)
+
+	deque.AddFirst(1)
+	deque.AddFirst(2)
+	deque.AddFirst(3)
+	deque.AddFirst(4)
+
+	f, ok = deque.First()
+	assert.True(t, ok)
+	assert.Equal(t, 4, f)
+}
+
+func TestLast(t *testing.T) {
+	deque := New[int]()
+
+	l, ok := deque.Last()
+	assert.False(t, ok)
+	assert.Equal(t, 0, l)
+
+	deque.AddFirst(1)
+	deque.AddFirst(2)
+	deque.AddFirst(3)
+	deque.AddFirst(4)
+
+	l, ok = deque.Last()
+	assert.True(t, ok)
+	assert.Equal(t, 1, l)
+}
+
+func TestAddFirst(t *testing.T) {
+	deque := New[int]()
+
+	f, ok := deque.First()
+	assert.False(t, ok)
+	assert.Equal(t, 0, f)
+
+	deque.AddFirst(1)
+	deque.AddFirst(2)
+
+	f, ok = deque.First()
+	assert.True(t, ok)
+	assert.Equal(t, 2, f)
+
+	deque.AddFirst(3)
+	deque.AddFirst(4)
+
+	f, ok = deque.First()
+	assert.True(t, ok)
+	assert.Equal(t, 4, f)
+}
+
+func TestAddLast(t *testing.T) {
+	deque := New[int]()
+
+	l, ok := deque.Last()
+	assert.False(t, ok)
+	assert.Equal(t, 0, l)
+
+	deque.AddLast(1)
+	deque.AddLast(2)
+
+	l, ok = deque.Last()
+	assert.True(t, ok)
+	assert.Equal(t, 2, l)
+
+	deque.AddLast(3)
+	deque.AddLast(4)
+
+	l, ok = deque.Last()
+	assert.True(t, ok)
+	assert.Equal(t, 4, l)
+}
+
+func TestRemoveFirst(t *testing.T) {
+	deque := New[int]()
+
+	f, ok := deque.RemoveFirst()
+	assert.False(t, ok)
+	assert.Equal(t, 0, f)
+
+	deque.AddFirst(1)
+	deque.AddFirst(2)
+	deque.AddFirst(3)
+	deque.AddFirst(4)
+
+	f, ok = deque.RemoveFirst()
+	assert.True(t, ok)
+	assert.Equal(t, 4, f)
+}
+
+func TestRemoveLast(t *testing.T) {
+	deque := New[int]()
+
+	l, ok := deque.RemoveLast()
+	assert.False(t, ok)
+	assert.Equal(t, 0, l)
+
+	deque.AddFirst(1)
+	deque.AddFirst(2)
+	deque.AddFirst(3)
+	deque.AddFirst(4)
+
+	l, ok = deque.RemoveLast()
+	assert.True(t, ok)
+	assert.Equal(t, 1, l)
+}
+
+func TestString(t *testing.T) {
+	deque := New[int]()
+
+	s := deque.String()
+	assert.Equal(t, "[ ]", s)
+
+	deque.AddFirst(1)
+	deque.AddFirst(2)
+	deque.AddFirst(3)
+	deque.AddLast(10)
+	deque.AddLast(20)
+	deque.AddFirst(4)
+
+	s = deque.String()
+	assert.Equal(t, "[ 4 3 2 1 10 20 ]", s)
+}

doc.go

@@ -0,0 +1,2 @@
+// Package deque implements a generic deque using a doubly-linked-list as the underlying data structure.
+package deque

go.mod

@@ -0,0 +1,14 @@
+module github.com/golang-ds/deque
+
+go 1.18
+
+require (
+	github.com/golang-ds/linkedlist v1.0.0
+	github.com/stretchr/testify v1.8.0
+)
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)

go.sum

@@ -0,0 +1,17 @@
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/golang-ds/linkedlist v1.0.0 h1:MrbDfIhQ9SL1my/siW/2va52kKO3IRCFdOa9EfzFFjM=
+github.com/golang-ds/linkedlist v1.0.0/go.mod h1:oRpzIKkdhV7lom4F8dgjDgq+1LGWs37Lge55MwXwNi8=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.8.0 h1:pSgiaMZlXftHpm5L7V1+rVB+AZJydKsMxsQBIJw4PKk=
+github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=