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tribool.go
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tribool.go
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package internal
import (
"strings"
)
// TriBool wraps a tri-state boolean value.
//
// See: https://en.wikipedia.org/wiki/Three-valued_logic
type TriBool int
const (
TriNoState TriBool = iota
TriFalse
TriTrue
)
func (s *TriBool) UnmarshalText(b []byte) error {
switch strings.ToLower(string(b)) {
case "true":
*s = TriTrue
case "false":
*s = TriFalse
default:
*s = TriNoState
}
return nil
}
func (s TriBool) MarshalText() (b []byte, err error) {
switch s {
case TriTrue:
b = []byte("true")
case TriFalse:
b = []byte("false")
default:
b = []byte("unset")
}
return
}
func (s TriBool) String() string {
switch s {
case TriTrue:
return "true"
case TriFalse:
return "false"
default:
return "unset"
}
}
func (s TriBool) Equal(b TriBool) bool {
if s == TriNoState {
return false
}
return s == b
}
func (s TriBool) And(b TriBool) TriBool {
if s == TriFalse || b == TriFalse {
return TriFalse
}
if s == TriNoState || b == TriNoState {
return TriNoState
}
return TriTrue
}
func (s TriBool) Or(b TriBool) TriBool {
if s == TriTrue || b == TriTrue {
return TriTrue
}
if s == TriNoState || b == TriNoState {
return TriNoState
}
return TriFalse
}
func (s TriBool) Xor(b TriBool) TriBool {
if s == TriNoState || b == TriNoState {
return TriNoState
}
if s != b {
return TriTrue
}
return TriFalse
}
func (s TriBool) Not() TriBool {
if s == TriNoState {
return s
}
if s == TriTrue {
return TriFalse
}
return TriTrue
}