[英]How to get sorted list of map keys in Go?
Let's imagine I have a map: map[string]string
. 让我们想象一下我有一张地图:
map[string]string
。 I would like to get the list of sorted keys for this map. 我想获取此地图的排序键列表。 So I could do something like this:
所以我可以这样做:
func SortedMapKeys(m map[string]string) (keyList []string) {
for key := range m {
keyList = append(keyList, key)
}
sort.Strings(keyList)
return
}
Then I will have another map of type map[string]bool
. 然后我将有另一个类型
map[string]bool
。 I would like to get it's keys also. 我也想得到它的钥匙。 But the problem is that function SortedMapKeys accepts a
map[string]string
argument. 但问题是函数SortedMapKeys接受
map[string]string
参数。 So I need to write exactly the same function, with the only one difference - it will accept a map[string]bool
. 所以我需要编写完全相同的函数,只有一个区别 - 它将接受
map[string]bool
。
For obvious reasons it's not an option. 出于显而易见的原因,这不是一种选择。 If one day I would like to change the logic of how I get and sort my keys, I will need to track and update all these functions.
如果有一天我想改变我获取和排序键的逻辑,我将需要跟踪和更新所有这些功能。 Also, I will have to write the same unit tests for all these functions which actually do the same thing since their bodies are 100% equal (code duplicate).
此外,我将不得不为所有这些函数编写相同的单元测试,这些函数实际上做同样的事情,因为它们的主体是100%相等(代码重复)。
Is there any way to create a generic function which could accept an map[string]
of whatever ? 有没有办法创建一个可以接受任何
map[string]
的通用函数?
Since map[string]bool
and map[string]string
and map[string]Whatever
are all distinct types, the only way to create a single function to sort the keys of all possible map[string]*
types is via reflection. 由于
map[string]bool
和map[string]string
和map[string]Whatever
是map[string]Whatever
都是不同的类型,创建单个函数来对所有可能的map[string]*
类型的键进行排序的唯一方法是通过反射。
func SortedMapKeys(m interface{}) (keyList []string) {
keys := reflect.ValueOf(m).MapKeys()
for _, key := range keys {
keyList = append(keyList, key.Interface().(string))
}
sort.Strings(keyList)
return
}
For an in-between solution, since there are probably only a few combinations of types you're concerned with, you can use a type switch to extract the keys 对于中间解决方案,因为您可能只关注几种类型的组合,您可以使用类型开关来提取密钥
func SortedMapKeys(m interface{}) (keyList []string) {
switch m := m.(type) {
case map[string]string:
for k := range m {
keyList = append(keyList, k)
}
case map[string]bool:
for k := range m {
keyList = append(keyList, k)
}
default:
panic("unknown map type")
}
sort.Strings(keyList)
return
}
Here's my 0.02$. 这是我的0.02美元。 Since keys extracting logic is unlikely to change and you want to keep everything in one place you can create variant and choose non-nil map from it:
由于密钥提取逻辑不太可能改变,并且您希望将所有内容保存在一个位置,因此您可以创建变量并从中选择非零映射:
type MapVariant struct {
Bool map[string]bool
String map[string]string
}
func SortedMapKeys(variant MapVariant) (keyList []string) {
if variant.String != nil {
for k := range variant.String {
keyList = append(keyList, k)
}
goto SORT
}
if variant.Bool != nil {
for k := range variant.Bool {
keyList = append(keyList, k)
}
goto SORT
}
SORT:
sort.Strings(keyList)
return
}
Of course you can avoid goto statements by adding more conditions but I personally find it clearer. 当然,您可以通过添加更多条件来避免goto语句,但我个人觉得它更清楚。
Then you can use the function like: 然后你可以使用像这样的功能:
SortedMapKeys(MapVariant{
Bool: map[string]bool{"a": true, "b": false}
})
SortedMapKeys(MapVariant{
String: map[string]string{"c": "v1", "b": "v2"}
})
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