status-go/vendor/github.com/anacrolix/missinggo/slices/cast.go

47 lines
1.3 KiB
Go

package slices
import (
"reflect"
"github.com/bradfitz/iter"
)
// Returns a copy of all the elements of slice []T as a slice of interface{}.
func ToEmptyInterface(slice interface{}) (ret []interface{}) {
v := reflect.ValueOf(slice)
l := v.Len()
ret = make([]interface{}, 0, l)
for i := range iter.N(v.Len()) {
ret = append(ret, v.Index(i).Interface())
}
return
}
// Makes and sets a slice at *ptrTo, and type asserts all the elements from
// from to it.
func MakeInto(ptrTo interface{}, from interface{}) {
fromSliceValue := reflect.ValueOf(from)
fromLen := fromSliceValue.Len()
if fromLen == 0 {
return
}
// Deref the pointer to slice.
slicePtrValue := reflect.ValueOf(ptrTo)
if slicePtrValue.Kind() != reflect.Ptr {
panic("destination is not a pointer")
}
destSliceValue := slicePtrValue.Elem()
// The type of the elements of the destination slice.
destSliceElemType := destSliceValue.Type().Elem()
destSliceValue.Set(reflect.MakeSlice(destSliceValue.Type(), fromLen, fromLen))
for i := range iter.N(fromSliceValue.Len()) {
// The value inside the interface in the slice element.
itemValue := fromSliceValue.Index(i)
if itemValue.Kind() == reflect.Interface {
itemValue = itemValue.Elem()
}
convertedItem := itemValue.Convert(destSliceElemType)
destSliceValue.Index(i).Set(convertedItem)
}
}