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state.go
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state.go
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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
}