Created
April 10, 2019 11:29
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Self-educational go snippet to learn about the empty interface{} type.
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// Self-educational go snippet to learn about the empty interface{} type. | |
// Based on @hvoecking's arbitrary structures traversal gist | |
// https://gist.github.com/hvoecking/10772475 | |
package main | |
import ( | |
"fmt" | |
"reflect" | |
"strings" | |
) | |
// Wrapper function for recursiveNestedToUpper to take and return `interface{}` | |
// but avoid switching between `reflect` types and `interface` types in each | |
// recursion. | |
func NestedToUpper(obj interface{}) interface{} { | |
return recursiveNestedToUpper(reflect.ValueOf(obj)).Interface() | |
} | |
// Recursive function to uppercase all strings in a nested slice of arbitrary | |
// depth. | |
func recursiveNestedToUpper(val reflect.Value) reflect.Value { | |
ret := reflect.New(val.Type()).Elem() | |
switch val.Kind() { | |
case reflect.Slice: | |
ret.Set(reflect.MakeSlice(val.Type(), val.Len(), val.Cap())) | |
for i := 0; i < val.Len(); i += 1 { | |
ret.Index(i).Set(recursiveNestedToUpper(val.Index(i))) | |
} | |
case reflect.String: | |
ret.SetString(strings.ToUpper(val.Interface().(string))) | |
} | |
return ret | |
} | |
func main() { | |
// Some nested replacing tests | |
l := []string{"foo"} | |
l = NestedToUpper(l).([]string) | |
fmt.Println(l) | |
ll := [][]string{{"bar"}} | |
ll = NestedToUpper(ll).([][]string) | |
fmt.Println(ll) | |
lll := [][][]string{{{"baz"}}} | |
lll = NestedToUpper(lll).([][][]string) | |
fmt.Println(lll) | |
} |
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