diff options
| -rw-r--r-- | src/libcore/iter.rs | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/src/libcore/iter.rs b/src/libcore/iter.rs index 0005db36c27..cfbccef2a72 100644 --- a/src/libcore/iter.rs +++ b/src/libcore/iter.rs @@ -1087,6 +1087,12 @@ impl<'a, I> DoubleEndedIterator for ByRef<'a, I> where I: 'a + DoubleEndedIterat fn next_back(&mut self) -> Option<<I as Iterator>::Item> { self.iter.next_back() } } +#[stable] +impl<'a, I> ExactSizeIterator for ByRef<'a, I> where I: 'a + ExactSizeIterator { + #[inline] + fn len(&self) -> uint { self.iter.len() } +} + /// A trait for iterators over elements which can be added together #[unstable = "needs to be re-evaluated as part of numerics reform"] pub trait AdditiveIterator<A> { @@ -1791,6 +1797,16 @@ impl<T, I> Iterator for Peekable<T, I> where I: Iterator<Item=T> { } #[stable] +impl<T, I> ExactSizeIterator for Peekable<T, I> where I: ExactSizeIterator<Item = T> { + #[inline] + fn len(&self) -> usize { + // This is guarenteed to not overflow because `len()` must have been able to return a valid + // value before we peeked. + self.iter.len() + if self.peeked.is_some() { 1 } else { 0 } + } +} + +#[stable] impl<T, I> Peekable<T, I> where I: Iterator<Item=T> { /// Return a reference to the next element of the iterator with out advancing it, /// or None if the iterator is exhausted. @@ -1982,6 +1998,12 @@ impl<I> RandomAccessIterator for Skip<I> where I: RandomAccessIterator{ } } +#[stable] +impl<I> ExactSizeIterator for Skip<I> where I: ExactSizeIterator { + #[inline] + fn len(&self) -> uint { self.iter.len().saturating_sub(self.n) } +} + /// An iterator that only iterates over the first `n` iterations of `iter`. #[derive(Clone)] #[must_use = "iterator adaptors are lazy and do nothing unless consumed"] @@ -2037,6 +2059,12 @@ impl<I> RandomAccessIterator for Take<I> where I: RandomAccessIterator{ } } +#[stable] +impl<I> ExactSizeIterator for Take<I> where I: ExactSizeIterator { + #[inline] + fn len(&self) -> uint { cmp::min(self.iter.len(), self.n) } +} + /// An iterator to maintain state while iterating another iterator #[must_use = "iterator adaptors are lazy and do nothing unless consumed"] @@ -2246,6 +2274,12 @@ impl<I> RandomAccessIterator for Fuse<I> where I: RandomAccessIterator { } } +#[stable] +impl<I> ExactSizeIterator for Fuse<I> where I: ExactSizeIterator { + #[inline] + fn len(&self) -> uint { self.iter.len() } +} + impl<I> Fuse<I> { /// Resets the fuse such that the next call to .next() or .next_back() will /// call the underlying iterator again even if it previously returned None. |