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use std::cmp::Ordering;
#[derive(Debug)]
pub enum Infinitable<T> {
Finite(T),
Infinity,
NegativeInfinity,
}
impl<T> Infinitable<T> {
pub fn is_finite(&self) -> bool {
match self {
&Infinitable::Finite(_) => true,
_ => false,
}
}
pub fn finite(self) -> Option<T> {
match self {
Infinitable::Finite(x) => Some(x),
_ => None,
}
}
}
impl<T> PartialEq for Infinitable<T> where T: PartialEq {
fn eq(&self, other: &Self) -> bool {
match (self, other) {
(&Infinitable::Infinity, &Infinitable::Infinity)
| (&Infinitable::NegativeInfinity, &Infinitable::NegativeInfinity)
=> true,
(&Infinitable::Finite(ref x), &Infinitable::Finite(ref y))
=> x == y,
(..)
=> false,
}
}
}
impl<T> Eq for Infinitable<T> where T: Eq {
}
impl<T> PartialOrd for Infinitable<T> where T: PartialOrd {
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
match (self, other) {
(&Infinitable::Infinity, &Infinitable::Infinity)
| (&Infinitable::NegativeInfinity, &Infinitable::NegativeInfinity)
=> Some(Ordering::Equal),
(&Infinitable::Infinity, _)
| (_, &Infinitable::NegativeInfinity)
=> Some(Ordering::Greater),
(&Infinitable::NegativeInfinity, _)
| (_, &Infinitable::Infinity)
=> Some(Ordering::Less),
(&Infinitable::Finite(ref x), &Infinitable::Finite(ref y))
=> x.partial_cmp(y),
}
}
}
impl<T> Ord for Infinitable<T> where T: Ord {
fn cmp(&self, other: &Self) -> Ordering {
match (self, other) {
(&Infinitable::Finite(ref x), &Infinitable::Finite(ref y))
=> x.cmp(y),
(..)
=> self.partial_cmp(other).unwrap(),
}
}
}