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slices.go
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/
slices.go
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package slices
import (
"reflect"
"github.com/pkg/errors"
)
func Union(arr1, arr2 interface{}) (reflect.Value, error) {
// Make sure inputs are slices.
if reflect.TypeOf(arr1).Kind() != reflect.Slice ||
reflect.TypeOf(arr2).Kind() != reflect.Slice {
return reflect.Value{}, errors.New("not a slice")
}
// Make sure both slices have compatible types.
if reflect.TypeOf(arr1) != reflect.TypeOf(arr2) {
return reflect.Value{}, errors.New("incompatible types")
}
// Put values of both slices as keys into a map to avoid repetitions.
items := make(map[interface{}]bool)
for _, arr := range [2]interface{}{arr1, arr2} {
slice := reflect.ValueOf(arr)
for i, n := 0, slice.Len(); i < n; i++ {
items[slice.Index(i).Interface()] = true
}
}
// Turn map keys into a slice and return it.
return sliceFromMap(items, arr1), nil
}
func Difference(arr1, arr2 interface{}) (reflect.Value, error) {
// Make sure inputs are slices.
if reflect.TypeOf(arr1).Kind() != reflect.Slice ||
reflect.TypeOf(arr2).Kind() != reflect.Slice {
return reflect.Value{}, errors.New("not a slice")
}
// Make sure both slices have compatible types.
if reflect.TypeOf(arr1) != reflect.TypeOf(arr2) {
return reflect.Value{}, errors.New("incompatible types")
}
// Put values of the first slice as keys into a map and then remove values
// of the second slice.
items := make(map[interface{}]bool)
slice1 := reflect.ValueOf(arr1)
for i, n := 0, slice1.Len(); i < n; i++ {
items[slice1.Index(i).Interface()] = true
}
slice2 := reflect.ValueOf(arr2)
for i, n := 0, slice2.Len(); i < n; i++ {
delete(items, slice2.Index(i).Interface())
}
// Turn map keys into a slice and return it.
return sliceFromMap(items, arr1), nil
}
func sliceFromMap(items map[interface{}]bool, arr interface{}) reflect.Value {
result := reflect.MakeSlice(reflect.TypeOf(arr), len(items), len(items))
i := 0
for item := range items {
result.Index(i).Set(reflect.ValueOf(item))
i++
}
return result
}