diff options
Diffstat (limited to 'src/libcore/iter/iterator.rs')
| -rw-r--r-- | src/libcore/iter/iterator.rs | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/src/libcore/iter/iterator.rs b/src/libcore/iter/iterator.rs index 30d09e5453b..26660cb3331 100644 --- a/src/libcore/iter/iterator.rs +++ b/src/libcore/iter/iterator.rs @@ -482,6 +482,53 @@ pub trait Iterator { Map{iter: self, f: f} } + /// Calls a closure on each element of an iterator. + /// + /// This is equivalent to using a [`for`] loop on the iterator, although + /// `break` and `continue` are not possible from a closure. It's generally + /// more idiomatic to use a `for` loop, but `for_each` may be more legible + /// when processing items at the end of longer iterator chains. In some + /// cases `for_each` may also be faster than a loop, because it will use + /// internal iteration on adaptors like `Chain`. + /// + /// [`for`]: ../../book/first-edition/loops.html#for + /// + /// # Examples + /// + /// Basic usage: + /// + /// ``` + /// #![feature(iterator_for_each)] + /// + /// use std::sync::mpsc::channel; + /// + /// let (tx, rx) = channel(); + /// (0..5).map(|x| x * 2 + 1) + /// .for_each(move |x| tx.send(x).unwrap()); + /// + /// let v: Vec<_> = rx.iter().collect(); + /// assert_eq!(v, vec![1, 3, 5, 7, 9]); + /// ``` + /// + /// For such a small example, a `for` loop may be cleaner, but `for_each` + /// might be preferable to keep a functional style with longer iterators: + /// + /// ``` + /// #![feature(iterator_for_each)] + /// + /// (0..5).flat_map(|x| x * 100 .. x * 110) + /// .enumerate() + /// .filter(|&(i, x)| (i + x) % 3 == 0) + /// .for_each(|(i, x)| println!("{}:{}", i, x)); + /// ``` + #[inline] + #[unstable(feature = "iterator_for_each", issue = "0")] + fn for_each<F>(self, mut f: F) where + Self: Sized, F: FnMut(Self::Item), + { + self.fold((), move |(), item| f(item)); + } + /// Creates an iterator which uses a closure to determine if an element /// should be yielded. /// |