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use std::cmp::{max, min};
use Diff;
fn modulo(a: isize, b: usize) -> usize {
let b = b as isize;
(((a % b) + b) % b) as usize
}
#[test]
fn test_modulo() {
assert_eq!(modulo(-11, 10), 9);
assert_eq!(modulo(23, 7), 2);
assert_eq!(modulo(-12, 6), 0);
}
pub fn diff<A, B: PartialEq<A>, D: Diff>(d: &mut D, e: &[A], f: &[B]) -> Result<(), D::Error> {
diff_offsets(d, e, f, 0, 0)?;
d.finish()
}
pub(crate) fn diff_offsets<D: Diff + ?Sized, A, B: PartialEq<A>>(
diff: &mut D,
e: &[A],
f: &[B],
i: usize,
j: usize,
) -> Result<(), D::Error> {
let n = e.len();
let m = f.len();
let l = (n + m) as isize;
let z = (2 * min(n, m) + 2) as usize;
if n > 0 && m > 0 {
let w = n as isize - m as isize;
let mut g = vec![0; z as usize];
let mut p = vec![0; z as usize];
for h in 0..=(l / 2 + l % 2) {
macro_rules! search {
($e: expr, $c: expr, $d: expr) => {
let (k0, k1) = {
let (m, n) = (m as isize, n as isize);
(-(h - 2*max(0, h - m)), h-2*max(0, h-n)+1)
};
for k in (k0..k1).step_by(2) {
let mut a: usize = if k == -h || k != h && $c[modulo(k-1, z)] < $c[modulo(k+1, z)] {
$c[modulo(k+1, z)]
} else {
$c[modulo(k-1, z)] + 1
};
let mut b = (a as isize - k) as usize;
let (s, t) = (a, b);
while a < n && b < m && {
let (e_i, f_i) = if $e { (a, b) } else { (n - a - 1, m - b - 1) };
f[f_i] == e[e_i]
} {
a += 1;
b += 1;
}
$c[modulo(k, z)] = a;
let bound = if $e { h-1 } else { h };
if (l%2 == 1) == $e
&& w-k >= -bound && w-k <= bound
&& $c[modulo(k, z)]+$d[modulo(w-k, z)] >= n
{
let (x, y, u, v) = if $e {
(s, t, a, b)
} else {
(n-a, m-b, n-s, m-t)
};
if h + bound > 1 || (x != u && y != v) {
diff_offsets(diff, &e[0..x], &f[0..y], i, j)?;
if x != u {
diff.equal(i + x, j + y, u-x)?;
}
diff_offsets(diff, &e[u..n], &f[v..m], i+u, j+v)?;
return Ok(())
} else if m > n {
diff.equal(i, j, n)?;
diff.insert(i+n, j+n, m-n)?;
return Ok(())
} else if m < n {
diff.equal(i, j, m)?;
diff.delete(i+m, n-m)?;
return Ok(())
} else {
return Ok(())
}
}
}
}
}
search!(true, g, p);
search!(false, p, g);
}
} else if n > 0 {
diff.delete(i, n)?
} else if m > 0 {
diff.insert(i, j, m)?
}
Ok(())
}