添加泛型Add函数,在指定位置插入元素 (#201)

* 添加泛型Add函数,在指定位置插入元素

* 修改CHANGELOG文件

.CHANGELOG.md

@@ -12,6 +12,7 @@
 - [mapx: LinkedMap 特性](https://github.com/ecodeclub/ekit/pull/191)
 - [copier: ReflectCopier 支持忽略字段](https://github.com/ecodeclub/ekit/pull/196)
 - [syncx: 重构LoadOrStoreFunc方法及相关测试](https://github.com/ecodeclub/ekit/pull/198)
+- [slice: 添加Add函数，在指定位置插入元素](https://github.com/ecodeclub/ekit/pull/201)
 
 # v0.0.7
 - [slice: FilterDelete](https://github.com/ecodeclub/ekit/pull/152)

internal/slice/add.go

@@ -0,0 +1,35 @@
+// Copyright 2021 ecodeclub
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package slice
+
+import "github.com/ecodeclub/ekit/internal/errs"
+
+func Add[T any](src []T, element T, index int) ([]T, error) {
+	length := len(src)
+	if index < 0 || index >= length {
+		return nil, errs.NewErrIndexOutOfRange(length, index)
+	}
+
+	//先将src扩展一个元素
+	var zeroValue T
+	src = append(src, zeroValue)
+	for i := len(src) - 1; i > index; i-- {
+		if i-1 >= 0 {
+			src[i] = src[i-1]
+		}
+	}
+	src[index] = element
+	return src, nil
+}

internal/slice/add_test.go

@@ -0,0 +1,78 @@
+// Copyright 2021 ecodeclub
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package slice
+
+import (
+	"testing"
+
+	"github.com/ecodeclub/ekit/internal/errs"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestAdd(t *testing.T) {
+	testCases := []struct {
+		name      string
+		slice     []int
+		addVal    int
+		index     int
+		wantSlice []int
+		wantErr   error
+	}{
+		{
+			name:      "index 0",
+			slice:     []int{123, 100},
+			addVal:    233,
+			index:     0,
+			wantSlice: []int{233, 123, 100},
+		},
+		{
+			name:      "index middle",
+			slice:     []int{123, 124, 125},
+			addVal:    233,
+			index:     1,
+			wantSlice: []int{123, 233, 124, 125},
+		},
+		{
+			name:    "index out of range",
+			slice:   []int{123, 100},
+			index:   12,
+			wantErr: errs.NewErrIndexOutOfRange(2, 12),
+		},
+		{
+			name:    "index less than 0",
+			slice:   []int{123, 100},
+			index:   -1,
+			wantErr: errs.NewErrIndexOutOfRange(2, -1),
+		},
+		{
+			name:      "index last",
+			slice:     []int{123, 100, 101, 102, 102, 102},
+			addVal:    233,
+			index:     5,
+			wantSlice: []int{123, 100, 101, 102, 102, 233, 102},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			res, err := Add(tc.slice, tc.addVal, tc.index)
+			assert.Equal(t, tc.wantErr, err)
+			if err != nil {
+				return
+			}
+			assert.Equal(t, tc.wantSlice, res)
+		})
+	}
+}

slice/add.go

@@ -0,0 +1,24 @@
+// Copyright 2021 ecodeclub
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package slice
+
+import "github.com/ecodeclub/ekit/internal/slice"
+
+// Add 在index处添加元素
+// index 范围应为[0, len(src))
+func Add[Src any](src []Src, element Src, index int) ([]Src, error) {
+	res, err := slice.Add[Src](src, element, index)
+	return res, err
+}

slice/add_test.go

@@ -0,0 +1,71 @@
+// Copyright 2021 ecodeclub
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package slice
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/ecodeclub/ekit/internal/errs"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestAdd(t *testing.T) {
+	// Delete 主要依赖于 internal/slice.Delete 来保证正确性
+	testCases := []struct {
+		name      string
+		slice     []int
+		addVal    int
+		index     int
+		wantSlice []int
+		wantErr   error
+	}{
+		{
+			name:      "index 0",
+			slice:     []int{123, 100},
+			addVal:    233,
+			index:     0,
+			wantSlice: []int{233, 123, 100},
+		},
+		{
+			name:    "index -1",
+			slice:   []int{123, 100},
+			index:   -1,
+			wantErr: errs.NewErrIndexOutOfRange(2, -1),
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			res, err := Add(tc.slice, tc.addVal, tc.index)
+			assert.Equal(t, tc.wantErr, err)
+			if err != nil {
+				return
+			}
+			assert.Equal(t, tc.wantSlice, res)
+		})
+	}
+}
+
+func ExampleAdd() {
+	res, _ := Add[int]([]int{1, 2, 3, 4}, 233, 2)
+	fmt.Println(res)
+	_, err := Add[int]([]int{1, 2, 3, 4}, 233, -1)
+	fmt.Println(err)
+	// Output:
+	// [1 2 233 3 4]
+	// ekit: 下标超出范围，长度 4, 下标 -1
+}