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use crate::ops::*;
/// Provides implementations for translate (also known as scroll) operations, and other internal data
/// movement operations such as flipping.
pub trait TranslateOps<T> : TooDeeOpsMut<T> {
/// Translate (or scroll) the entire area. The `mid` coordinate will be moved to (0, 0), and
/// all other elements will be moved in the same fashion. All the original data is preserved by
/// wrapping at the array edges.
///
/// If you don't want the wrapped data, simply overwrite it after translation.
///
/// # Examples
///
/// ```
/// use toodee::{TooDee,TooDeeOps,TranslateOps};
/// let v = vec![42u32; 15];
/// let mut toodee : TooDee<u32> = TooDee::from_vec(5, 3, v);
/// toodee[1][1] = 1;
/// // move (1, 1) to (0, 0)
/// toodee.translate_with_wrap((1, 1));
/// assert_eq!(toodee[0][0], 1);
/// assert_eq!(toodee[1][1], 42);
/// ```
///
/// ```
/// use toodee::{TooDee,TooDeeOps,TranslateOps};
/// let v = vec![42u32; 15];
/// let mut toodee : TooDee<u32> = TooDee::from_vec(5, 3, v);
/// // set (4, 2) to 1
/// toodee[(4, 2)] = 1;
/// // move (4, 2) to (0, 0)
/// toodee.translate_with_wrap((4, 2));
/// assert_eq!(toodee[0][0], 1);
/// assert_eq!(toodee[2][4], 42);
/// ```
fn translate_with_wrap(&mut self, mid: Coordinate) {
let (mut col_mid, mut row_mid) = mid;
let num_cols = self.num_cols();
let num_rows = self.num_rows();
assert!(col_mid <= num_cols);
assert!(row_mid <= num_rows);
if col_mid == num_cols {
col_mid = 0;
}
if row_mid == num_rows {
row_mid = 0;
}
if row_mid == 0 {
if col_mid != 0 {
// apply column rotation only
for r in self.rows_mut() {
r.rotate_left(col_mid);
}
}
return;
}
let row_adj_abs = num_rows - row_mid;
// This row swapping algorithm is pretty cool. I came up with it independently,
// but it turns out that the concept is fairly well known. See
// `core::slice::ptr_rotate()` for various strategies.
let mut swap_count = 0;
let mut base_row = 0;
while swap_count < num_rows {
let mut mid = col_mid;
let mut next_row = base_row + row_adj_abs;
loop {
if next_row >= num_rows {
next_row -= num_rows;
}
swap_count += 1;
if base_row == next_row {
// finish up with a rotate
if mid > 0 {
unsafe {
self.get_unchecked_row_mut(base_row).rotate_left(mid);
}
}
break;
} else {
// The following logic performs a rotate while swapping, and
// is more efficient than doing a swap then rotate.
let (base_ref, next_ref) = self.row_pair_mut(base_row, next_row);
unsafe {
if mid > 0 {
base_ref.get_unchecked_mut(..mid).swap_with_slice(next_ref.get_unchecked_mut(num_cols-mid..num_cols));
}
if mid < num_cols {
base_ref.get_unchecked_mut(mid..num_cols).swap_with_slice(next_ref.get_unchecked_mut(..num_cols-mid));
}
}
mid += col_mid;
if mid >= num_cols {
mid -= num_cols;
}
}
next_row += row_adj_abs;
}
// TODO: We now know that we'll loop a further N = (num_rows / swap_count - 1) times.
// This means we could start swapping in chunks of N, i.e.,
// ([base_row..base_row+N] -> [base_row+row_adj_abs..base_row+row_adj_abs+N],
// which should more cache-friendly.
if swap_count >= num_rows {
break;
}
base_row += 1; // advance the base
}
}
/// Flips (or mirrors) the rows.
///
/// # Examples
///
/// ```
/// use toodee::{TooDee,TooDeeOps,TranslateOps};
/// let v = vec![42u32; 15];
/// let mut toodee : TooDee<u32> = TooDee::from_vec(5, 3, v);
/// toodee[0][1] = 1;
/// toodee.flip_rows();
/// assert_eq!(toodee[2][1], 1);
/// ```
fn flip_rows(&mut self) {
let mut iter = self.rows_mut();
while let (Some(r1), Some(r2)) = (iter.next(), iter.next_back()) {
r1.swap_with_slice(r2);
}
}
/// Flips (or mirrors) the columns.
///
/// ```
/// use toodee::{TooDee,TooDeeOps,TranslateOps};
/// let v = vec![42u32; 15];
/// let mut toodee : TooDee<u32> = TooDee::from_vec(5, 3, v);
/// toodee[1][1] = 1;
/// toodee.flip_cols();
/// assert_eq!(toodee[1][3], 1);
/// ```
fn flip_cols(&mut self) {
for r in self.rows_mut() {
r.reverse();
}
}
}
impl<T, O> TranslateOps<T> for O where O : TooDeeOpsMut<T> {}