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1. 引入 matchFunc 2. 简化 slice 中查找类型的 API 3. 引入 Find 和 FindAll 方法
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,43 @@ | ||
| // 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 | ||
|
|
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| // Find 查找元素 | ||
| // 如果没有找到，第二个返回值返回 false | ||
| func Find[T any](src []T, match matchFunc[T]) (T, bool) { | ||
| for _, val := range src { | ||
| if match(val) { | ||
| return val, true | ||
| } | ||
| } | ||
| var t T | ||
| return t, false | ||
| } | ||
|
|
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| // FindAll 查找所有符合条件的元素 | ||
| // 永远不会返回 nil | ||
| func FindAll[T any](src []T, match matchFunc[T]) []T { | ||
| // 我们认为符合条件元素应该是少数 | ||
| // 所以会除以 8 | ||
| // 也就是触发扩容的情况下，最多三次就会和原本的容量一样 | ||
| // +1 是为了保证，至少有一个元素 | ||
| res := make([]T, 0, len(src)>>3+1) | ||
| for _, val := range src { | ||
| if match(val) { | ||
| res = append(res, val) | ||
| } | ||
| } | ||
| return res | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,149 @@ | ||
| // 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" | ||
|
|
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| "github.com/stretchr/testify/assert" | ||
| ) | ||
|
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| func TestFind(t *testing.T) { | ||
| testCases := []struct { | ||
| name string | ||
| input []Number | ||
| match matchFunc[Number] | ||
|
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| wantVal Number | ||
| found bool | ||
| }{ | ||
| { | ||
| name: "找到了", | ||
| input: []Number{ | ||
| {val: 123}, | ||
| {val: 234}, | ||
| }, | ||
| match: func(src Number) bool { | ||
| return src.val == 123 | ||
| }, | ||
| wantVal: Number{val: 123}, | ||
| found: true, | ||
| }, | ||
| { | ||
| name: "没找到", | ||
| input: []Number{ | ||
| {val: 123}, | ||
| {val: 234}, | ||
| }, | ||
| match: func(src Number) bool { | ||
| return src.val == 456 | ||
| }, | ||
| }, | ||
| { | ||
| name: "nil", | ||
| match: func(src Number) bool { | ||
| return src.val == 123 | ||
| }, | ||
| }, | ||
| { | ||
| name: "没有元素", | ||
| input: []Number{}, | ||
| match: func(src Number) bool { | ||
| return src.val == 123 | ||
| }, | ||
| }, | ||
| } | ||
| for _, tc := range testCases { | ||
| t.Run(tc.name, func(t *testing.T) { | ||
| val, found := Find[Number](tc.input, tc.match) | ||
| assert.Equal(t, tc.found, found) | ||
| assert.Equal(t, tc.wantVal, val) | ||
| }) | ||
| } | ||
| } | ||
|
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| func TestFindAll(t *testing.T) { | ||
| testCases := []struct { | ||
| name string | ||
| input []Number | ||
| match matchFunc[Number] | ||
|
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| wantVals []Number | ||
| }{ | ||
| { | ||
| name: "没有符合条件的", | ||
| input: []Number{{val: 2}, {val: 4}}, | ||
| match: func(src Number) bool { | ||
| return src.val%2 == 1 | ||
| }, | ||
| wantVals: []Number{}, | ||
| }, | ||
| { | ||
| name: "找到了", | ||
| input: []Number{{val: 2}, {val: 3}, {val: 4}}, | ||
| match: func(src Number) bool { | ||
| return src.val%2 == 1 | ||
| }, | ||
| wantVals: []Number{{val: 3}}, | ||
| }, | ||
| { | ||
| name: "nil", | ||
| match: func(src Number) bool { | ||
| return src.val%2 == 1 | ||
| }, | ||
| wantVals: []Number{}, | ||
| }, | ||
| } | ||
|
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| for _, tc := range testCases { | ||
| t.Run(tc.name, func(t *testing.T) { | ||
| vals := FindAll[Number](tc.input, tc.match) | ||
| assert.Equal(t, tc.wantVals, vals) | ||
| }) | ||
| } | ||
| } | ||
|
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| func ExampleFind() { | ||
| val, ok := Find[int]([]int{1, 2, 3}, func(src int) bool { | ||
| return src == 2 | ||
| }) | ||
| fmt.Println(val, ok) | ||
| val, ok = Find[int]([]int{1, 2, 3}, func(src int) bool { | ||
| return src == 4 | ||
| }) | ||
| fmt.Println(val, ok) | ||
| // Output: | ||
| // 2 true | ||
| // 0 false | ||
| } | ||
|
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| func ExampleFindAll() { | ||
| vals := FindAll[int]([]int{2, 3, 4}, func(src int) bool { | ||
| return src%2 == 1 | ||
| }) | ||
| fmt.Println(vals) | ||
| vals = FindAll[int]([]int{2, 3, 4}, func(src int) bool { | ||
| return src > 5 | ||
| }) | ||
| fmt.Println(vals) | ||
| // Output: | ||
| // [3] | ||
| // [] | ||
| } | ||
|
|
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| type Number struct { | ||
| val int | ||
| } |
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