Function decodeMap

docstore/driver/codec.go:595–625

Since a map value is not settable via reflection, this function always creates a new element for each corresponding map key. Existing values of v are overwritten. This happens even if the map value is something like a pointer to a struct, where we could in theory populate the existing struct value i

(v reflect.Value, d Decoder)

// we could in theory populate the existing struct value instead of discarding it.
// This behavior matches encoding/json.
func decodeMap(v reflect.Value, d Decoder) error {
	mapLen, ok := d.MapLen()
	if !ok {
		return decodingError(v, d)
	}
	t := v.Type()
	if v.IsNil() {
		v.Set(reflect.MakeMapWithSize(t, mapLen))
	}
	et := t.Elem()
	var err error
	kt := v.Type().Key()
	d.DecodeMap(func(key string, vd Decoder, _ bool) bool {
		if err != nil {
			return false
		}
		el := reflect.New(et).Elem()
		err = decode(el, vd)
		if err != nil {
			return false
		}
		vk, e := unstringifyMapKey(key, kt)
		if e != nil {
			err = e
			return false
		}
		v.SetMapIndex(vk, el)
		return err == nil
	})
	return err
}

// Given a map key encoded as a string, and the type of the map key, convert the key
// into the type.