unique.go

package main

import (
	"fmt"
	"reflect"
)

type Plop struct {
	A string
}

func main() {
	a := []string{"a", "b", "c", "b"}
	b := []int64{1, 22, 3, 1, 2}
	c := []Plop{Plop{A: "A"}, Plop{A: "A"}, Plop{A: "B"}}

	unique(&a)
	unique(&b)
	unique(&c)

	fmt.Println(a)
	fmt.Println(b)
	fmt.Println(c)
}

func unique(ptr interface{}) {
	slice := reflect.ValueOf(ptr).Elem().Interface()
	switch reflect.TypeOf(slice).Kind() {
	case reflect.Slice:
		seen := map[interface{}]bool{}

		s := reflect.ValueOf(slice)
		sliceType := reflect.TypeOf(s.Index(0).Interface())
		typedSlice := reflect.SliceOf(sliceType)
		uniq := reflect.MakeSlice(typedSlice, 0, 0)

		for i := 0; i < s.Len(); i++ {
			if !seen[s.Index(i).Interface()] {
				seen[s.Index(i).Interface()] = true
				uniq = reflect.Append(uniq, s.Index(i))
			}
		}
		reflect.ValueOf(ptr).Elem().Set(uniq)
	}
}