func unmarshalList()

in marshal.go [1665:1725]
58 lines of code
15 McCabe index (conditional complexity)

func unmarshalList(info TypeInfo, data []byte, value interface{}) error {
	listInfo, ok := info.(CollectionType)
	if !ok {
		return unmarshalErrorf("unmarshal: can not unmarshal none collection type into list")
	}

	rv := reflect.ValueOf(value)
	if rv.Kind() != reflect.Ptr {
		return unmarshalErrorf("can not unmarshal into non-pointer %T", value)
	}
	rv = rv.Elem()
	t := rv.Type()
	k := t.Kind()

	switch k {
	case reflect.Slice, reflect.Array:
		if data == nil {
			if k == reflect.Array {
				return unmarshalErrorf("unmarshal list: can not store nil in array value")
			}
			if rv.IsNil() {
				return nil
			}
			rv.Set(reflect.Zero(t))
			return nil
		}
		n, p, err := readCollectionSize(listInfo, data)
		if err != nil {
			return err
		}
		data = data[p:]
		if k == reflect.Array {
			if rv.Len() != n {
				return unmarshalErrorf("unmarshal list: array with wrong size")
			}
		} else {
			rv.Set(reflect.MakeSlice(t, n, n))
		}
		for i := 0; i < n; i++ {
			m, p, err := readCollectionSize(listInfo, data)
			if err != nil {
				return err
			}
			data = data[p:]
			// In case m < 0, the value is null, and unmarshalData should be nil.
			var unmarshalData []byte
			if m >= 0 {
				if len(data) < m {
					return unmarshalErrorf("unmarshal list: unexpected eof")
				}
				unmarshalData = data[:m]
				data = data[m:]
			}
			if err := Unmarshal(listInfo.Elem, unmarshalData, rv.Index(i).Addr().Interface()); err != nil {
				return err
			}
		}
		return nil
	}
	return unmarshalErrorf("can not unmarshal %s into %T. Accepted types: *slice, *array.", info, value)
}