package vm import ( "strings" "github.com/pkg/errors" ) // State of the VM. type State uint8 // Available States. const ( noneState State = 0 haltState State = 1 << iota faultState breakState ) // HasFlag checks for State flag presence. func (s State) HasFlag(f State) bool { return s&f != 0 } // String implements the stringer interface. func (s State) String() string { if s == noneState { return "NONE" } ss := make([]string, 0, 3) if s.HasFlag(haltState) { ss = append(ss, "HALT") } if s.HasFlag(faultState) { ss = append(ss, "FAULT") } if s.HasFlag(breakState) { ss = append(ss, "BREAK") } return strings.Join(ss, ", ") } // StateFromString converts string into the VM State. func StateFromString(s string) (st State, err error) { if s = strings.TrimSpace(s); s == "NONE" { return noneState, nil } ss := strings.Split(s, ",") for _, state := range ss { switch state = strings.TrimSpace(state); state { case "HALT": st |= haltState case "FAULT": st |= faultState case "BREAK": st |= breakState default: return 0, errors.New("unknown state") } } return } // MarshalJSON implements the json.Marshaler interface. func (s State) MarshalJSON() (data []byte, err error) { return []byte(`"` + s.String() + `"`), nil } // UnmarshalJSON implements the json.Marshaler interface. func (s *State) UnmarshalJSON(data []byte) (err error) { l := len(data) if l < 2 || data[0] != '"' || data[l-1] != '"' { return errors.New("wrong format") } *s, err = StateFromString(string(data[1 : l-1])) return }