gat-lending-iterator 0.1.8

A library for iterators who's items can [mutably] reference the iterator.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96

use std::ops::Deref;

use crate::LendingIterator;

/// A lending iterator that copies the elements of an underlying lending iterator.
///
/// This `struct` is created by the [`copied`] method on [`LendingIterator`]. See
/// its documentation for more.
///
/// [`LendingIterator`]: crate::LendingIterator
/// [`copied`]: crate::LendingIterator::copied
#[derive(Clone, Debug)]
#[must_use = "iterators are lazy and do nothing unless consumed"]
pub struct Copied<I> {
    iter: I,
}

impl<I> Copied<I> {
    pub(crate) fn new(iter: I) -> Copied<I> {
        Copied { iter }
    }
}

impl<I> LendingIterator for Copied<I>
where
    I: LendingIterator,
    for<'a> I::Item<'a>: Deref,
    for<'a> <I::Item<'a> as Deref>::Target: Copy,
{
    type Item<'a>
        = <I::Item<'a> as Deref>::Target
    where
        Self: 'a;

    fn next(&mut self) -> Option<Self::Item<'_>> {
        self.iter.next().map(|item| *item)
    }

    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        self.iter.size_hint()
    }

    #[inline]
    fn nth(&mut self, n: usize) -> Option<Self::Item<'_>> {
        self.iter.nth(n).map(|item| *item)
    }

    #[inline]
    fn count(self) -> usize {
        self.iter.count()
    }
}

pub struct IntoIter<I> {
    iter: I,
}

impl<I, T> Iterator for IntoIter<I>
where
    I: LendingIterator,
    for<'a> I::Item<'a>: Deref<Target = T>,
    T: Copy,
{
    type Item = T;

    fn next(&mut self) -> Option<Self::Item> {
        self.iter.next().map(|item| *item)
    }
}

impl<I, T> IntoIterator for Copied<I>
where
    I: LendingIterator,
    for<'a> I::Item<'a>: Deref<Target = T>,
    T: Copy,
{
    type Item = T;
    type IntoIter = IntoIter<I>;

    fn into_iter(self) -> Self::IntoIter {
        IntoIter { iter: self.iter }
    }
}

#[cfg(test)]
mod tests {
    use crate::{LendingIterator, ToLendingIterator};

    #[test]
    fn copied_basic() {
        let data = vec![1, 2, 3];
        let result: Vec<_> = data.lend_refs().copied().into_iter().collect();
        assert_eq!(result, vec![1, 2, 3]);
    }
}