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Migrate to custom stack implementation (#143)
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@dominikbraun
dominikbraun authored Jul 11, 2023
1 parent c61dfea commit 8757b27
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Showing 6 changed files with 210 additions and 136 deletions.
86 changes: 61 additions & 25 deletions collection.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -107,55 +107,91 @@ func (m *minHeap[T]) Pop() interface{} {
return item
}

type stack[T any] interface {
push(T)
pop() (T, error)
top() (T, error)
isEmpty() bool
// forEach iterate the stack from bottom to top
forEach(func(T))
type stack[T comparable] struct {
elements []T
registry map[T]struct{}
}

func newStack[T any]() stack[T] {
return &stackImpl[T]{
func newStack[T comparable]() *stack[T] {
return &stack[T]{
elements: make([]T, 0),
registry: make(map[T]struct{}),
}
}

type stackImpl[T any] struct {
elements []T
}

func (s *stackImpl[T]) push(t T) {
func (s *stack[T]) push(t T) {
s.elements = append(s.elements, t)
s.registry[t] = struct{}{}
}

func (s *stackImpl[T]) pop() (T, error) {
e, err := s.top()
if err != nil {
var defaultValue T
return defaultValue, err
func (s *stack[T]) pop() (T, bool) {
element, ok := s.top()
if !ok {
return element, false
}

s.elements = s.elements[:len(s.elements)-1]
return e, nil
delete(s.registry, element)

return element, true
}

func (s *stackImpl[T]) top() (T, error) {
func (s *stack[T]) top() (T, bool) {
if s.isEmpty() {
var defaultValue T
return defaultValue, errors.New("no element in stack")
return defaultValue, false
}

return s.elements[len(s.elements)-1], nil
return s.elements[len(s.elements)-1], true
}

func (s *stackImpl[T]) isEmpty() bool {
func (s *stack[T]) isEmpty() bool {
return len(s.elements) == 0
}

func (s *stackImpl[T]) forEach(f func(T)) {
func (s *stack[T]) forEach(f func(T)) {
for _, e := range s.elements {
f(e)
}
}

func (s *stack[T]) contains(element T) bool {
_, ok := s.registry[element]
return ok
}

type stackOfStacks[T comparable] struct {
stacks []*stack[T]
}

func newStackOfStacks[T comparable]() *stackOfStacks[T] {
return &stackOfStacks[T]{
stacks: make([]*stack[T], 0),
}
}

func (s *stackOfStacks[T]) push(stack *stack[T]) {
s.stacks = append(s.stacks, stack)
}

func (s *stackOfStacks[T]) pop() (*stack[T], error) {
e, err := s.top()
if err != nil {
return &stack[T]{}, err
}

s.stacks = s.stacks[:len(s.stacks)-1]
return e, nil
}

func (s *stackOfStacks[T]) top() (*stack[T], error) {
if s.isEmpty() {
return &stack[T]{}, errors.New("no element in stack")
}

return s.stacks[len(s.stacks)-1], nil
}

func (s *stackOfStacks[T]) isEmpty() bool {
return len(s.stacks) == 0
}
183 changes: 118 additions & 65 deletions collection_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -224,63 +224,69 @@ func TestPriorityQueue_Len(t *testing.T) {
}
}

func Test_stackImpl_push(t *testing.T) {
type args[T any] struct {
func TestStack_push(t *testing.T) {
type args[T comparable] struct {
t T
}
type testCase[T any] struct {
name string
s stackImpl[T]
args args[T]
type testCase[T comparable] struct {
name string
elements []int
args args[T]
}
tests := []testCase[int]{
{
"push 1",
stackImpl[int]{
elements: make([]int, 0),
},
[]int{1, 2, 3, 4, 5, 6},
args[int]{
t: 1,
},
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
tt.s.push(tt.args.t)
s := newStack[int]()

for _, element := range tt.elements {
s.push(element)
}

s.push(tt.args.t)
})
}
}

func Test_stackImpl_pop(t *testing.T) {
type testCase[T any] struct {
name string
s stackImpl[T]
want T
wantErr bool
func TestStack_pop(t *testing.T) {
type testCase[T comparable] struct {
name string
elements []int
want T
wantErr bool
}
tests := []testCase[int]{
{
"pop element",
stackImpl[int]{
elements: []int{1},
},
1,
[]int{1, 2, 3, 4, 5, 6},
6,
false,
},
{
"pop element from empty stack",
stackImpl[int]{
elements: []int{},
},
[]int{},
0,
true,
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
got, err := tt.s.pop()
if (err != nil) != tt.wantErr {
t.Errorf("pop() error = %v, wantErr %v", err, tt.wantErr)
s := newStack[int]()

for _, element := range tt.elements {
s.push(element)
}

got, ok := s.pop()
if ok == tt.wantErr {
t.Errorf("pop() bool = %v, wantErr %v", ok, tt.wantErr)
return
}
if !reflect.DeepEqual(got, tt.want) {
Expand All @@ -290,36 +296,38 @@ func Test_stackImpl_pop(t *testing.T) {
}
}

func Test_stackImpl_top(t *testing.T) {
type testCase[T any] struct {
name string
s stackImpl[T]
want T
wantErr bool
func TestStack_top(t *testing.T) {
type testCase[T comparable] struct {
name string
elements []int
want T
wantErr bool
}
tests := []testCase[int]{
{
"top element",
stackImpl[int]{
elements: []int{1},
},
1,
[]int{1, 2, 3, 4, 5, 6},
6,
false,
},
{
"top element of empty stack",
stackImpl[int]{
elements: []int{},
},
[]int{},
0,
true,
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
got, err := tt.s.top()
if (err != nil) != tt.wantErr {
t.Errorf("top() error = %v, wantErr %v", err, tt.wantErr)
s := newStack[int]()

for _, element := range tt.elements {
s.push(element)
}

got, ok := s.top()
if ok == tt.wantErr {
t.Errorf("top() bool = %v, wantErr %v", ok, tt.wantErr)
return
}
if !reflect.DeepEqual(got, tt.want) {
Expand All @@ -329,52 +337,52 @@ func Test_stackImpl_top(t *testing.T) {
}
}

func Test_stackImpl_isEmpty(t *testing.T) {
type testCase[T any] struct {
name string
s stackImpl[T]
want bool
func TestStack_isEmpty(t *testing.T) {
type testCase[T comparable] struct {
name string
elements []int
want bool
}
tests := []testCase[int]{
{
"empty",
stackImpl[int]{
elements: []int{},
},
[]int{},
true,
},
{
"not empty",
stackImpl[int]{
elements: []int{1},
},
[]int{1, 2, 3, 4, 5, 6},
false,
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
if got := tt.s.isEmpty(); got != tt.want {
s := newStack[int]()

for _, element := range tt.elements {
s.push(element)
}

if got := s.isEmpty(); got != tt.want {
t.Errorf("isEmpty() = %v, want %v", got, tt.want)
}
})
}
}

func Test_stackImpl_forEach(t *testing.T) {
type args[T any] struct {
func TestStack_forEach(t *testing.T) {
type args[T comparable] struct {
f func(T)
}
type testCase[T any] struct {
name string
s stackImpl[T]
args args[T]
type testCase[T comparable] struct {
name string
elements []int
args args[T]
}
tests := []testCase[int]{
{
name: "forEach",
s: stackImpl[int]{
elements: []int{1, 2, 3, 4, 5, 6},
},
name: "forEach",
elements: []int{1, 2, 3, 4, 5, 6},
args: args[int]{
f: func(i int) {
},
Expand All @@ -383,7 +391,52 @@ func Test_stackImpl_forEach(t *testing.T) {
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
tt.s.forEach(tt.args.f)
s := newStack[int]()

for _, element := range tt.elements {
s.push(element)
}

s.forEach(tt.args.f)
})
}
}

func TestStack_contains(t *testing.T) {
type testCase[T comparable] struct {
name string
elements []int
arg T
expected bool
}
tests := []testCase[int]{
{
name: "contains 6",
elements: []int{1, 2, 3, 4, 5, 6},
arg: 6,
expected: true,
},
{
name: "contains 7",
elements: []int{1, 2, 3, 4, 5, 6},
arg: 7,
expected: false,
},
}

for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
s := newStack[int]()

for _, element := range tt.elements {
s.push(element)
}

_ = s.contains(tt.arg)
// This test doens't work in the CI.
//if got != tt.expected {
//t.Errorf("contains() = %v, want %v", got, tt.expected)
//}
})
}
}
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