对pr#63进行代码优化

ecodeclub · Sep 1, 2022 · 4f8f4ff · 4f8f4ff
1 parent 11bed82
commit 4f8f4ff
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Showing 3 changed files with 128 additions and 34 deletions.
diff --git a/.CHANGELOG.md b/.CHANGELOG.md
@@ -11,6 +11,7 @@
 [ekit: 修复 Pool TestPool](https://github.com/gotomicro/ekit/pull/40)
 [ekit: 实现了 LinkedList Range](https://github.com/gotomicro/ekit/pull/46)
 [ekit: 实现了 TaskPool](https://github.com/gotomicro/ekit/pull/57)
+[ekit: 实现了 ArrayList Delete 方法缩容](https://github.com/gotomicro/ekit/pull/63)
 - [ekit: add ToPtr function](https://github.com/gotomicro/ekit/pull/6)
 - [sql: 支持 JsonColumn](https://github.com/gotomicro/ekit/pull/7)
 - [bean/copier: 实现了基于反射的 ReflectCopier](https://github.com/gotomicro/ekit/pull/47)
@@ -28,4 +29,5 @@
   - [Range](https://github.com/gotomicro/ekit/pull/46)
 - [pool: 修复 Pool TestPool 测试不稳定的问题](https://github.com/gotomicro/ekit/pull/40)
 - [ekit：引入 golangci-lint 和 goimports](https://github.com/gotomicro/ekit/pull/54)
-- [ekit: 实现了 TaskPool](https://github.com/gotomicro/ekit/pull/57)
+- [ekit: 实现了 TaskPool](https://github.com/gotomicro/ekit/pull/57)
+- [ekit: 实现了 ArrayList Delete 方法缩容](https://github.com/gotomicro/ekit/pull/63)
diff --git a/list/array_list.go b/list/array_list.go
@@ -86,37 +86,31 @@ func (a *ArrayList[T]) Delete(index int) (T, error) {
 		}
 	}
 	a.vals = a.vals[:j]
-	if a.Cap() > 64 {
-		a.arrShrinkage()
-	}
+	a.shrink()
 	return res, nil
 }
 
 // arrShrinkage 数组缩容
-func (a *ArrayList[T]) arrShrinkage() {
+func (a *ArrayList[T]) shrink() {
 	var newCap int
 	c, l := a.Cap(), a.Len()
 	if c <= 64 {
 		return
 	}
-	// 如果当前容量 > 2048，元素是容量的 1/2的时候缩容
 	if c > 2048 && (c/l >= 2) {
-		// 缩到已有容量的 5/8
 		newCap = int(float32(c) * float32(0.625))
-	} else if c <= 2048 && (c/l >= 4) { // 如果当前容量 <=2048，元素是容量的四分之一的时候缩容
-		// 缩到原本的一半
+	} else if c <= 2048 && (c/l >= 4) {
 		newCap = c / 2
-		// 当容量小于64的时候，不需要继续缩容了
 		if newCap < 64 {
 			newCap = 64
 		}
 	} else {
 		// 不满足缩容
 		return
 	}
-	newList := NewArrayList[T](newCap)
-	_ = newList.Append(a.vals...)
-	a.vals = newList.vals
+	newSlice := make([]T, 0, newCap)
+	newSlice = append(newSlice, a.vals...)
+	a.vals = newSlice
 }
 
 func (a *ArrayList[T]) Len() int {

diff --git a/list/array_list_test.go b/list/array_list_test.go
@@ -272,31 +272,129 @@ func TestArrayList_Delete(t *testing.T) {
 }
 
 // TestArrayList_Delete_Shrinkage 测试缩容
-func TestArrayList_Delete_Shrinkage(t *testing.T) {
-	// case : cap大于2048，元素是容量的 1/2。 target:已有容量的 5/8
-	list := NewArrayList[int](4000)
-	for i := 0; i < 999; i++ {
-		_ = list.Append(i)
-	}
-	_, _ = list.Delete(0)
-	assert.Equal(t, int(4000*0.625), list.Cap())
+func TestArrayList_Delete_Shrink(t *testing.T) {
+	testCases := []struct {
+		name    string // 用例名称
+		cap     int    // 原始容量
+		loop    int    // 切片中元素个数
+		wantCap int    // 期望缩容后的容量
+	}{
+		// ----- #阶段一 逻辑测试# -----
+		// 只测试需求的逻辑和代码的逻辑是否一致
 
-	// case : cap小于等于2048，元素是容量的四分之一。 target:缩到原本的一半
-	list = NewArrayList[int](2048)
-	for i := 0; i < 300; i++ {
-		_ = list.Append(i)
+		// case 1: cap小于等于64，不进行缩容
+		{
+			name:    "case 1",
+			cap:     64,
+			loop:    1,
+			wantCap: 64,
+		},
+		// case 2: cap大于2048，元素是容量的 1/2。 target:已有容量的 5/8
+		{
+			name:    "case 2",
+			cap:     4000,
+			loop:    999,
+			wantCap: 2500,
+		},
+		// case 3: cap小于等于2048，元素是容量的四分之一。 target:缩到原本的一半
+		{
+			name:    "case 3",
+			cap:     2048,
+			loop:    300,
+			wantCap: 1024,
+		},
+		// case 4: cap > 2048，但不满足缩容条件的例子
+		{
+			name:    "case 4",
+			cap:     4000,
+			loop:    3888,
+			wantCap: 4000,
+		},
+		// case 5: cap <= 2048，但不满足缩容条件的例子
+		{
+			name:    "case 5",
+			cap:     2048,
+			loop:    666,
+			wantCap: 2048,
+		},
+
+		// ----- #阶段二 边界测试# -----
+		// 测试用例边界
+		// ps:测试时：
+		//		（1）会默认删除一个元素，loop需要+1
+		//		（2）测试结果向下取整
+
+		// case 6: cap65
+		{
+			name:    "case 6",
+			cap:     65,
+			loop:    2,
+			wantCap: 64,
+		},
+		// case 6-2:  cap65,loop为16
+		{
+			name:    "case 6-2",
+			cap:     65,
+			loop:    16,
+			wantCap: 64,
+		},
+		// case 6-3:  cap130,loop为34，删除一个元素后为33，刚好不满足四分之一
+		{
+			name:    "case 6-3",
+			cap:     130,
+			loop:    34,
+			wantCap: 130,
+		},
+		// case 7 cap2047
+		{
+			name:    "case 7",
+			cap:     2047,
+			loop:    10,
+			wantCap: 1023, // 1023.5 ，向下取整
+		},
+		{
+			name:    "case 7-1",
+			cap:     2047,
+			loop:    512,
+			wantCap: 1023,
+		},
+		{
+			name:    "case 7-2",
+			cap:     2047,
+			loop:    513, // 四分之一为511.75，513删除一个元素512刚好不满足
+			wantCap: 2047,
+		},
+		//  case 8 : cap 2049
+		{
+			name:    "case 8",
+			cap:     2049,
+			loop:    10,
+			wantCap: 1280, // 1280.625 ，向下取整
+		},
+		{
+			name:    "case 8-1",
+			cap:     2049,
+			loop:    1025,
+			wantCap: 1280, // 1280.625 ，向下取整
+		},
+		{
+			name:    "case 8-2",
+			cap:     2049,
+			loop:    1026, // 二分之一为1024，1026删除一个元素后1025刚好不满足
+			wantCap: 2049,
+		},
 	}
-	_, _ = list.Delete(0)
-	assert.Equal(t, int(2048*0.5), list.Cap())
 
-	// case : cap小于等于2048，元素是容量的四分之一。 target:缩到原本的一半
-	// ps:当容量小于64的时候，容量为64
-	list = NewArrayList[int](100)
-	for i := 0; i < 10; i++ {
-		_ = list.Append(i)
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			list := NewArrayList[int](tc.cap)
+			for i := 0; i < tc.loop; i++ {
+				_ = list.Append(i)
+			}
+			_, _ = list.Delete(0)
+			assert.Equal(t, tc.wantCap, list.Cap())
+		})
 	}
-	_, _ = list.Delete(0)
-	assert.Equal(t, 64, list.Cap())
 }
 
 func TestArrayList_Len(t *testing.T) {