diff options
| -rw-r--r-- | src/libcore/iterator.rs | 79 |
1 files changed, 79 insertions, 0 deletions
diff --git a/src/libcore/iterator.rs b/src/libcore/iterator.rs index 58850190d8b..bf286470296 100644 --- a/src/libcore/iterator.rs +++ b/src/libcore/iterator.rs @@ -18,6 +18,7 @@ implementing the `Iterator` trait. */ use prelude::*; +use num::{Zero, One}; pub trait Iterator<A> { /// Advance the iterator and return the next value. Return `None` when the end is reached. @@ -205,6 +206,51 @@ impl<A, T: Iterator<A>> IteratorUtil<A> for T { fn count(&mut self) -> uint { self.fold(0, |cnt, _x| cnt + 1) } } +pub trait AdditiveIterator<A> { + fn sum(&mut self) -> A; +} + +impl<A: Add<A, A> + Zero, T: Iterator<A>> AdditiveIterator<A> for T { + #[inline(always)] + fn sum(&mut self) -> A { self.fold(Zero::zero::<A>(), |s, x| s + x) } +} + +pub trait MultiplicativeIterator<A> { + fn product(&mut self) -> A; +} + +impl<A: Mul<A, A> + One, T: Iterator<A>> MultiplicativeIterator<A> for T { + #[inline(always)] + fn product(&mut self) -> A { self.fold(One::one::<A>(), |p, x| p * x) } +} + +pub trait OrdIterator<A> { + fn max(&mut self) -> Option<A>; + fn min(&mut self) -> Option<A>; +} + +impl<A: Ord, T: Iterator<A>> OrdIterator<A> for T { + #[inline(always)] + fn max(&mut self) -> Option<A> { + self.fold(None, |max, x| { + match max { + None => Some(x), + Some(y) => Some(cmp::max(x, y)) + } + }) + } + + #[inline(always)] + fn min(&mut self) -> Option<A> { + self.fold(None, |min, x| { + match min { + None => Some(x), + Some(y) => Some(cmp::min(x, y)) + } + }) + } +} + pub struct ChainIterator<T, U> { priv a: T, priv b: U, @@ -675,4 +721,37 @@ mod tests { assert_eq!(v.slice(0, 10).iter().count(), 10); assert_eq!(v.slice(0, 0).iter().count(), 0); } + + #[test] + fn test_iterator_sum() { + let v = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; + assert_eq!(v.slice(0, 4).iter().transform(|&x| x).sum(), 6); + assert_eq!(v.iter().transform(|&x| x).sum(), 55); + assert_eq!(v.slice(0, 0).iter().transform(|&x| x).sum(), 0); + } + + #[test] + fn test_iterator_product() { + let v = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; + assert_eq!(v.slice(0, 4).iter().transform(|&x| x).product(), 0); + assert_eq!(v.slice(1, 5).iter().transform(|&x| x).product(), 24); + assert_eq!(v.slice(0, 0).iter().transform(|&x| x).product(), 1); + } + + #[test] + fn test_iterator_max() { + let v = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; + assert_eq!(v.slice(0, 4).iter().transform(|&x| x).max(), Some(3)); + assert_eq!(v.iter().transform(|&x| x).max(), Some(10)); + assert_eq!(v.slice(0, 0).iter().transform(|&x| x).max(), None); + } + + #[test] + fn test_iterator_min() { + let v = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; + assert_eq!(v.slice(0, 4).iter().transform(|&x| x).min(), Some(0)); + assert_eq!(v.iter().transform(|&x| x).min(), Some(0)); + assert_eq!(v.slice(0, 0).iter().transform(|&x| x).min(), None); + } + } |