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Add ptr/non-ptr versions of Peek & Pop

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This commit is contained in:
Evan Burkey 2023-07-07 12:36:17 -07:00
parent 96a00272db
commit 6ef75cdc94
2 changed files with 53 additions and 13 deletions
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28
stack.go
View File

@ -23,7 +23,18 @@ func (s *Stack[T]) Size() int {
return s.size
}
func (s *Stack[T]) Pop() (*T, error) {
func (s *Stack[T]) Pop() (T, error) {
if s.size == 0 {
var t T
return t, fmt.Errorf("tried to pop empty stack")
}
t := s.arr[s.size-1]
s.arr = s.arr[:s.size-1]
s.size--
return t, nil
}
func (s *Stack[T]) PopPtr() (*T, error) {
if s.size == 0 {
return nil, fmt.Errorf("tried to pop empty stack")
}
@ -38,11 +49,18 @@ func (s *Stack[T]) Push(t T) {
s.size++
}
func (s *Stack[T]) Peek() T {
func (s *Stack[T]) Peek() (T, error) {
if s.size == 0 {
var t T
return t, fmt.Errorf("tried to peek empty stack")
}
t := s.arr[s.size-1]
return t
return t, nil
}
func (s *Stack[T]) PeekPtr() *T {
return &(s.arr[s.size-1])
func (s *Stack[T]) PeekPtr() (*T, error) {
if s.size == 0 {
return nil, fmt.Errorf("tried to peek empty stack")
}
return &(s.arr[s.size-1]), nil
}

38
stack_test.go
View File

@ -15,8 +15,14 @@ func TestStackPush(t *testing.T) {
s.Push(2)
s.Push(10)
assert.Equal(t, s.Peek(), 10)
assert.Equal(t, *s.PeekPtr(), 10)
p, err := s.Peek()
assert.Equal(t, p, 10)
assert.NoError(t, err)
pp, err := s.PeekPtr()
assert.NotNil(t, pp)
assert.NoError(t, err)
assert.Equal(t, *pp, 10)
}
func TestStackPop(t *testing.T) {
@ -25,15 +31,26 @@ func TestStackPop(t *testing.T) {
s.Push(10)
x, err := s.Pop()
assert.NotNil(t, x)
assert.NoError(t, err)
assert.Equal(t, *x, 10)
assert.Equal(t, x, 10)
y, err := s.PopPtr()
assert.NotNil(t, y)
assert.NoError(t, err)
assert.Equal(t, *y, 2)
}
func TestStackPopEmpty(t *testing.T) {
s := NewStack[int]()
x, err := s.Pop()
assert.Error(t, err)
assert.Zero(t, x)
}
func TestStackPopPtrEmpty(t *testing.T) {
s := NewStack[int]()
x, err := s.PopPtr()
assert.Error(t, err)
assert.Nil(t, x)
}
@ -53,17 +70,22 @@ func TestStackComplete(t *testing.T) {
s.Push(3)
assert.Equal(t, s.Size(), 3)
x := s.Peek()
x, err := s.Peek()
assert.NoError(t, err)
assert.Equal(t, 3, x)
y := s.PeekPtr()
y, err := s.PeekPtr()
assert.NotNil(t, y)
assert.NoError(t, err)
assert.Equal(t, 3, *y)
z, err := s.Pop()
assert.NoError(t, err)
assert.Equal(t, *z, 3)
assert.Equal(t, s.Peek(), 2)
assert.Equal(t, z, 3)
p, err := s.Peek()
assert.NoError(t, err)
assert.Equal(t, p, 2)
assert.Equal(t, s.Size(), 2)
s.Clear()