itertools/
repeatn.rs

1use std::iter::FusedIterator;
2
3/// An iterator that produces *n* repetitions of an element.
4///
5/// See [`repeat_n()`](crate::repeat_n) for more information.
6#[must_use = "iterators are lazy and do nothing unless consumed"]
7#[derive(Clone, Debug)]
8pub struct RepeatN<A> {
9    elt: Option<A>,
10    n: usize,
11}
12
13/// Create an iterator that produces `n` repetitions of `element`.
14pub fn repeat_n<A>(element: A, n: usize) -> RepeatN<A>
15    where A: Clone,
16{
17    if n == 0 {
18        RepeatN { elt: None, n, }
19    } else {
20        RepeatN { elt: Some(element), n, }
21    }
22}
23
24impl<A> Iterator for RepeatN<A>
25    where A: Clone
26{
27    type Item = A;
28
29    fn next(&mut self) -> Option<Self::Item> {
30        if self.n > 1 {
31            self.n -= 1;
32            self.elt.as_ref().cloned()
33        } else {
34            self.n = 0;
35            self.elt.take()
36        }
37    }
38
39    fn size_hint(&self) -> (usize, Option<usize>) {
40        (self.n, Some(self.n))
41    }
42}
43
44impl<A> DoubleEndedIterator for RepeatN<A>
45    where A: Clone
46{
47    #[inline]
48    fn next_back(&mut self) -> Option<Self::Item> {
49        self.next()
50    }
51}
52
53impl<A> ExactSizeIterator for RepeatN<A>
54    where A: Clone
55{}
56
57impl<A> FusedIterator for RepeatN<A>
58    where A: Clone
59{}
itertools/repeatn.rs

itertools/
repeatn.rs
