38 typedef signed char repr_t;
39 enum value_t : repr_t { no_value = -1, maybe_value = 0, yes_value = 1 };
49 : val_(v ? yes_value : no_value)
56 static trival from_repr_t(repr_t v)
58 return trival(
static_cast<value_t
>(v));
62 constexpr
explicit trival(value_t v)
67 static constexpr
trival maybe() noexcept
75 return val_ != maybe_value;
78 constexpr
bool is_maybe()
const
80 return val_ == maybe_value;
83 constexpr
bool is_true()
const
85 return val_ == yes_value;
88 constexpr
bool is_false()
const
90 return val_ == no_value;
93 constexpr value_t val()
const
102 explicit operator bool()
const
104 return val_ == yes_value;
107 constexpr trival operator!()
const
109 return trival((val_ == yes_value) ? no_value :
110 (val_ == no_value) ? yes_value :
123 constexpr
bool operator==(trival a, trival b)
125 return a.val() == b.val();
128 constexpr
bool operator!=(trival a, trival b)
134 constexpr trival operator&&(trival a, trival b)
137 (a.val() == trival::no_value || b.val() == trival::no_value)
139 : (a.val() == trival::maybe_value || b.val() == trival::maybe_value)
144 constexpr trival operator&&(
bool a, trival b)
146 return trival(a) && b;
149 constexpr trival operator&&(trival a,
bool b)
151 return a && trival(b);
154 constexpr trival operator||(trival a, trival b)
157 (a.val() == trival::yes_value || b.val() == trival::yes_value)
159 : (a.val() == trival::maybe_value || b.val() == trival::maybe_value)
164 constexpr trival operator||(
bool a, trival b)
166 return trival(a) || b;
169 constexpr trival operator||(trival a,
bool b)
171 return a || trival(b);
174 inline std::ostream& operator<<(std::ostream& os, trival v)
176 return os << ((v.val() == trival::no_value) ?
"no"
177 : (v.val() == trival::maybe_value) ?
"maybe"
A class implementing Kleene's three-valued logic.
Definition: trival.hh:34
constexpr bool is_known() const
Is true or false, but not maybe.
Definition: trival.hh:73
Definition: automata.hh:27