From eb59d02a0898fe67721c4babf6f2424192abede7 Mon Sep 17 00:00:00 2001
From: dudaodong <lanliddd.2007@163.com>
Date: Fri, 4 Feb 2022 19:35:06 +0800
Subject: [PATCH] feat: add stackarray.go implements stack with array

---
 datastructure/node.go            | 13 +++++-
 datastructure/stackarray.go      | 62 +++++++++++++++++++++++++
 datastructure/stackarray_test.go | 77 ++++++++++++++++++++++++++++++++
 3 files changed, 151 insertions(+), 1 deletion(-)
 create mode 100644 datastructure/stackarray.go
 create mode 100644 datastructure/stackarray_test.go

diff --git a/datastructure/node.go b/datastructure/node.go
index bf89e31..db3b5d4 100644
--- a/datastructure/node.go
+++ b/datastructure/node.go
@@ -1,13 +1,24 @@
 package datastructure
 
-// LinkNode is a linkedlist node, which have a value and Pre points to previous node, Next points to a next node of the link.
+// LinkNode is a linkedlist node, which have a Value and Pre points to previous node, Next points to a next node of the link.
 type LinkNode[T any] struct {
 	Value T
 	Pre   *LinkNode[T]
 	Next  *LinkNode[T]
 }
 
+// NewLinkNode return a LinkNode pointer
 func NewLinkNode[T any](value T) *LinkNode[T] {
 	return &LinkNode[T]{value, nil, nil}
 }
 
+// StackNode is a node in stack, which have a Value and Pre points to previous node in the stack.
+type StackNode[T any] struct {
+	Value T
+	Pre   *StackNode[T]
+}
+
+// NewStackNode return a StackNode pointer
+func NewStackNode[T any](value T) *StackNode[T] {
+	return &StackNode[T]{value, nil}
+}
diff --git a/datastructure/stackarray.go b/datastructure/stackarray.go
new file mode 100644
index 0000000..a4efde0
--- /dev/null
+++ b/datastructure/stackarray.go
@@ -0,0 +1,62 @@
+package datastructure
+
+import "errors"
+
+// StackArray is a linear table, implemented with slice
+type StackArray[T any] struct {
+	data   []T
+	length int
+}
+
+// NewStackArray return a empty StackArray pointer
+func NewStackArray[T any]() *StackArray[T] {
+	return &StackArray[T]{data: []T{}, length: 0}
+}
+
+// Data return stack data
+func (s *StackArray[T]) Data() []T {
+	return s.data
+}
+
+// Length return length of stack data
+func (s *StackArray[T]) Length() int {
+	return s.length
+}
+
+// IsEmpty checks if stack is empty or not
+func (s *StackArray[T]) IsEmpty() bool {
+	return s.length == 0
+}
+
+// Push element into stack
+func (s *StackArray[T]) Push(value T) {
+	s.data = append([]T{value}, s.data...)
+	s.length++
+}
+
+// Pop delete the top element of stack then return it, if stack is empty, return nil and error
+func (s *StackArray[T]) Pop() (*T, error) {
+	if s.IsEmpty() {
+		return nil, errors.New("stack is empty")
+	}
+
+	topItem := s.data[0]
+	s.data = s.data[1:]
+	s.length--
+
+	return &topItem, nil
+}
+
+// Peak return the top element of stack then return it
+func (s *StackArray[T]) Peak() (*T, error) {
+	if s.IsEmpty() {
+		return nil, errors.New("stack is empty")
+	}
+	return &s.data[0], nil
+}
+
+// EmptyStack clear the stack data
+func (s *StackArray[T]) EmptyStack() {
+	s.data = []T{}
+	s.length = 0
+}
diff --git a/datastructure/stackarray_test.go b/datastructure/stackarray_test.go
new file mode 100644
index 0000000..6de2bdc
--- /dev/null
+++ b/datastructure/stackarray_test.go
@@ -0,0 +1,77 @@
+package datastructure
+
+import (
+	"testing"
+
+	"github.com/duke-git/lancet/internal"
+)
+
+func TestStackArray_Push(t *testing.T) {
+	assert := internal.NewAssert(t, "TestStackArray_Push")
+
+	stack := NewStackArray[int]()
+	stack.Push(1)
+	stack.Push(2)
+	stack.Push(3)
+
+	expected := []int{3, 2, 1}
+	values := stack.Data()
+	length := stack.Length()
+
+	assert.Equal(expected, values)
+	assert.Equal(3, length)
+}
+
+func TestStackArray_Pop(t *testing.T) {
+	assert := internal.NewAssert(t, "TestStackArray_Pop")
+
+	stack := NewStackArray[int]()
+	topItem, err := stack.Pop()
+	assert.IsNotNil(err)
+
+	stack.Push(1)
+	stack.Push(2)
+	stack.Push(3)
+
+	topItem, err = stack.Pop()
+	assert.IsNil(err)
+	assert.Equal(3, *topItem)
+
+	expected := []int{2, 1}
+	assert.Equal(expected, stack.Data())
+}
+
+func TestStackArray_Peak(t *testing.T) {
+	assert := internal.NewAssert(t, "TestStackArray_Peak")
+
+	stack := NewStackArray[int]()
+	topItem, err := stack.Peak()
+	assert.IsNotNil(err)
+
+	stack.Push(1)
+	stack.Push(2)
+	stack.Push(3)
+
+	topItem, err = stack.Peak()
+	assert.IsNil(err)
+	assert.Equal(3, *topItem)
+
+	expected := []int{3, 2, 1}
+	assert.Equal(expected, stack.Data())
+}
+
+func TestStackArray_Empty(t *testing.T) {
+	assert := internal.NewAssert(t, "TestStackArray_Empty")
+
+	stack := NewStackArray[int]()
+	assert.Equal(true, stack.IsEmpty())
+	assert.Equal(0, stack.Length())
+
+	stack.Push(1)
+	assert.Equal(false, stack.IsEmpty())
+	assert.Equal(1, stack.Length())
+
+	stack.EmptyStack()
+	assert.Equal(true, stack.IsEmpty())
+	assert.Equal(0, stack.Length())
+}