diff options
| -rw-r--r-- | src/libcore/iter/mod.rs | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/src/libcore/iter/mod.rs b/src/libcore/iter/mod.rs index 3999db0d63c..5dce60b79c9 100644 --- a/src/libcore/iter/mod.rs +++ b/src/libcore/iter/mod.rs @@ -1099,6 +1099,16 @@ impl<I: Iterator, P> Iterator for Filter<I, P> where P: FnMut(&I::Item) -> bool let (_, upper) = self.iter.size_hint(); (0, upper) // can't know a lower bound, due to the predicate } + + #[inline] + fn count(self) -> usize { + let (mut c, mut predicate, mut iter) = (0, self.predicate, self.iter); + for x in iter.by_ref() { + // branchless count + c += (&mut predicate)(&x) as usize; + } + c + } } #[stable(feature = "rust1", since = "1.0.0")] |