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| -rw-r--r-- | src/libcore/iter.rs | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/src/libcore/iter.rs b/src/libcore/iter.rs index b2736609cf7..3f1808a0396 100644 --- a/src/libcore/iter.rs +++ b/src/libcore/iter.rs @@ -1050,6 +1050,30 @@ pub trait Iterator { /// // got a false, take_while() isn't used any more /// assert_eq!(iter.next(), None); /// ``` + /// + /// Because `take_while()` needs to look at the value in order to see if it + /// should be included or not, consuming iterators will see that it is + /// removed: + /// + /// ``` + /// let a = [1, 2, 3, 4]; + /// let mut iter = a.into_iter(); + /// + /// let result: Vec<i32> = iter.by_ref() + /// .take_while(|n| **n != 3) + /// .cloned() + /// .collect(); + /// + /// assert_eq!(result, &[1, 2]); + /// + /// let result: Vec<i32> = iter.cloned().collect(); + /// + /// assert_eq!(result, &[4]); + /// ``` + /// + /// The `3` is no longer there, because it was consumed in order to see if + /// the iteration should stop, but wasn't placed back into the iterator or + /// some similar thing. #[inline] #[stable(feature = "rust1", since = "1.0.0")] fn take_while<P>(self, predicate: P) -> TakeWhile<Self, P> where |