p3_matrix/
stack.rs

1use core::ops::Deref;
2
3use crate::Matrix;
4
5/// A combination of two matrices, stacked together vertically.
6#[derive(Copy, Clone, Debug)]
7pub struct VerticalPair<First, Second> {
8    first: First,
9    second: Second,
10}
11
12impl<First, Second> VerticalPair<First, Second> {
13    pub fn new<T>(first: First, second: Second) -> Self
14    where
15        T: Send + Sync,
16        First: Matrix<T>,
17        Second: Matrix<T>,
18    {
19        assert_eq!(first.width(), second.width());
20        Self { first, second }
21    }
22}
23
24impl<T: Send + Sync, First: Matrix<T>, Second: Matrix<T>> Matrix<T>
25    for VerticalPair<First, Second>
26{
27    fn width(&self) -> usize {
28        self.first.width()
29    }
30
31    fn height(&self) -> usize {
32        self.first.height() + self.second.height()
33    }
34
35    type Row<'a> = EitherRow<First::Row<'a>, Second::Row<'a>> where Self: 'a;
36
37    fn get(&self, r: usize, c: usize) -> T {
38        if r < self.first.height() {
39            self.first.get(r, c)
40        } else {
41            self.second.get(r - self.first.height(), c)
42        }
43    }
44
45    fn row(&self, r: usize) -> Self::Row<'_> {
46        if r < self.first.height() {
47            EitherRow::Left(self.first.row(r))
48        } else {
49            EitherRow::Right(self.second.row(r - self.first.height()))
50        }
51    }
52
53    fn row_slice(&self, r: usize) -> impl Deref<Target = [T]> {
54        if r < self.first.height() {
55            EitherRow::Left(self.first.row_slice(r))
56        } else {
57            EitherRow::Right(self.second.row_slice(r - self.first.height()))
58        }
59    }
60}
61
62/// We use this to wrap both the row iterator and the row slice.
63#[derive(Debug)]
64pub enum EitherRow<L, R> {
65    Left(L),
66    Right(R),
67}
68
69impl<T, L, R> Iterator for EitherRow<L, R>
70where
71    L: Iterator<Item = T>,
72    R: Iterator<Item = T>,
73{
74    type Item = T;
75
76    fn next(&mut self) -> Option<Self::Item> {
77        match self {
78            EitherRow::Left(l) => l.next(),
79            EitherRow::Right(r) => r.next(),
80        }
81    }
82}
83
84impl<T, L, R> Deref for EitherRow<L, R>
85where
86    L: Deref<Target = [T]>,
87    R: Deref<Target = [T]>,
88{
89    type Target = [T];
90    fn deref(&self) -> &Self::Target {
91        match self {
92            EitherRow::Left(l) => l,
93            EitherRow::Right(r) => r,
94        }
95    }
96}
p3_matrix/stack.rs

p3_matrix/
stack.rs
