use free::put_back;
use structs::PutBack;
pub enum Diff<I, J>
where I: Iterator,
J: Iterator
{
FirstMismatch(usize, PutBack<I>, PutBack<J>),
Shorter(usize, PutBack<I>),
Longer(usize, PutBack<J>),
}
pub fn diff_with<I, J, F>(i: I, j: J, is_equal: F)
-> Option<Diff<I::IntoIter, J::IntoIter>>
where I: IntoIterator,
J: IntoIterator,
F: Fn(&I::Item, &J::Item) -> bool
{
let mut i = i.into_iter();
let mut j = j.into_iter();
let mut idx = 0;
while let Some(i_elem) = i.next() {
match j.next() {
None => return Some(Diff::Shorter(idx, put_back(i).with_value(i_elem))),
Some(j_elem) => if !is_equal(&i_elem, &j_elem) {
let remaining_i = put_back(i).with_value(i_elem);
let remaining_j = put_back(j).with_value(j_elem);
return Some(Diff::FirstMismatch(idx, remaining_i, remaining_j));
},
}
idx += 1;
}
j.next().map(|j_elem| Diff::Longer(idx, put_back(j).with_value(j_elem)))
}