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Rational that reduce to ints should print like ints #15329

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Rational that reduce to ints should print like ints #15329

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449d318
rebasing: Rational that reduce to ints should print like ints
pfalabella Jul 2, 2014
ff62755
Merge remote-tracking branch 'upstream/master' into rational-show
pfalabella Jul 2, 2014
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45 changes: 28 additions & 17 deletions src/libnum/rational.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -274,12 +274,17 @@ impl<T: Clone + Integer + PartialOrd>
Num for Ratio<T> {}

/* String conversions */
impl<T: fmt::Show> fmt::Show for Ratio<T> {
/// Renders as `numer/denom`.
impl<T: fmt::Show + Eq + One> fmt::Show for Ratio<T> {
/// Renders as `numer/denom`. If denom=1, renders as numer.
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "{}/{}", self.numer, self.denom)
if self.denom == One::one() {
write!(f, "{}", self.numer)
} else {
write!(f, "{}/{}", self.numer, self.denom)
}
}
}

impl<T: ToStrRadix> ToStrRadix for Ratio<T> {
/// Renders as `numer/denom` where the numbers are in base `radix`.
fn to_str_radix(&self, radix: uint) -> String {
Expand All @@ -291,21 +296,20 @@ impl<T: ToStrRadix> ToStrRadix for Ratio<T> {

impl<T: FromStr + Clone + Integer + PartialOrd>
FromStr for Ratio<T> {
/// Parses `numer/denom`.
/// Parses `numer/denom` or just `numer`
fn from_str(s: &str) -> Option<Ratio<T>> {
let split: Vec<&str> = s.splitn('/', 1).collect();
if split.len() < 2 {
return None
let mut split = s.splitn('/', 1);

let num = split.next().and_then(|n| FromStr::from_str(n));
let den = split.next().or(Some("1")).and_then(|d| FromStr::from_str(d));

match (num, den) {
(Some(n), Some(d)) => Some(Ratio::new(n, d)),
_ => None
}
let a_option: Option<T> = FromStr::from_str(*split.get(0));
a_option.and_then(|a| {
let b_option: Option<T> = FromStr::from_str(*split.get(1));
b_option.and_then(|b| {
Some(Ratio::new(a.clone(), b.clone()))
})
})
}
}

impl<T: FromStrRadix + Clone + Integer + PartialOrd>
FromStrRadix for Ratio<T> {
/// Parses `numer/denom` where the numbers are in base `radix`.
Expand Down Expand Up @@ -429,6 +433,13 @@ mod test {
assert!(!_neg1_2.is_integer());
}

#[test]
fn test_show() {
assert_eq!(format!("{}", _2), "2".to_string());
assert_eq!(format!("{}", _1_2), "1/2".to_string());
assert_eq!(format!("{}", _0), "0".to_string());
assert_eq!(format!("{}", Ratio::from_integer(-2i)), "-2".to_string());
}

mod arith {
use super::{_0, _1, _2, _1_2, _3_2, _neg1_2, to_big};
Expand Down Expand Up @@ -562,11 +573,11 @@ mod test {
assert_eq!(FromStr::from_str(s.as_slice()), Some(r));
assert_eq!(r.to_str(), s);
}
test(_1, "1/1".to_string());
test(_0, "0/1".to_string());
test(_1, "1".to_string());
test(_0, "0".to_string());
test(_1_2, "1/2".to_string());
test(_3_2, "3/2".to_string());
test(_2, "2/1".to_string());
test(_2, "2".to_string());
test(_neg1_2, "-1/2".to_string());
}
#[test]
Expand Down