bjoernager/rust
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Add examples of ordered retain

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Josh Stone 2019-05-10 18:01:50 -07:00
parent 9b3583375d
commit 0545375ca6
3 changed files with 34 additions and 0 deletions
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10
src/liballoc/vec.rs
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@ -947,6 +947,16 @@ impl<T> Vec<T> {
/// vec.retain(|&x| x%2 == 0);
/// assert_eq!(vec, [2, 4]);
/// ```
///
/// The exact order may be useful for tracking external state, like an index.
///
/// ```
/// let mut vec = vec![1, 2, 3, 4, 5];
/// let keep = [false, true, true, false, true];
/// let mut i = 0;
/// vec.retain(|_| (keep[i], i += 1).0);
/// assert_eq!(vec, [2, 3, 5]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn retain<F>(&mut self, mut f: F)
where F: FnMut(&T) -> bool