use core::{marker::PhantomData, mem};
macro_rules! impl_iter (
($dr_matrix_iter:ident, $data_ptr:ty, $data_type:ty, $split_at:ident) => (
#[derive(Debug)]
pub struct $dr_matrix_iter<'a, T> {
cols: usize,
curr_row: usize,
data: $data_type,
phantom: PhantomData<&'a T>,
rows: usize,
}
impl<'a, T> $dr_matrix_iter<'a, T> {
pub(crate) fn new(
rows: usize,
cols: usize,
data: $data_type,
) -> Self {
Self {
cols,
curr_row: 0,
data,
phantom: PhantomData,
rows,
}
}
pub fn split_at(self, idx: usize) -> (Self, Self) {
let current_len = self.rows - self.curr_row;
assert!(idx <= current_len);
let slice_point = self.curr_row + idx;
let (data_head, data_tail) = self.data.$split_at((slice_point - self.curr_row) * self.cols);
(
$dr_matrix_iter {
curr_row: self.curr_row,
data: data_head,
rows: slice_point,
cols: self.cols,
phantom: PhantomData,
},
$dr_matrix_iter {
curr_row: slice_point,
data: data_tail,
cols: self.cols,
rows: self.rows,
phantom: PhantomData,
}
)
}
}
impl<'a, T> DoubleEndedIterator for $dr_matrix_iter<'a, T> {
fn next_back(&mut self) -> Option<Self::Item> {
if self.curr_row >= self.rows {
return None;
}
let data = mem::take(&mut self.data);
let (data_head, data_tail) = data.$split_at(data.len() - self.cols);
self.data = data_head;
self.rows -= 1;
Some(data_tail)
}
}
impl<'a, T> ExactSizeIterator for $dr_matrix_iter<'a, T> {
}
impl<'a, T> Iterator for $dr_matrix_iter<'a, T> {
type Item = $data_type;
fn next(&mut self) -> Option<Self::Item> {
if self.curr_row >= self.rows {
return None;
}
let data = mem::take(&mut self.data);
let (data_head, data_tail) = data.$split_at(self.cols);
self.data = data_tail;
self.curr_row += 1;
Some(data_head)
}
fn size_hint(&self) -> (usize, Option<usize>) {
(self.rows, Some(self.rows))
}
}
);
);
impl_iter!(DrMatrixRowIter, *const T, &'a [T], split_at);
impl_iter!(DrMatrixRowIterMut, *mut T, &'a mut [T], split_at_mut);