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use std::slice;
use std::iter::Peekable;
use RoaringBitmap;
use super::container::Container;
struct Pairs<'a>(Peekable<slice::Iter<'a, Container>>, Peekable<slice::Iter<'a, Container>>);
impl RoaringBitmap {
fn pairs<'a>(&'a self, other: &'a RoaringBitmap) -> Pairs<'a> {
Pairs(self.containers.iter().peekable(), other.containers.iter().peekable())
}
pub fn is_disjoint(&self, other: &Self) -> bool {
self.pairs(other)
.filter(|&(c1, c2)| c1.is_some() && c2.is_some())
.all(|(c1, c2)| c1.unwrap().is_disjoint(c2.unwrap()))
}
pub fn is_subset(&self, other: &Self) -> bool {
for pair in self.pairs(other) {
match pair {
(None, _) => (),
(_, None) => { return false; },
(Some(c1), Some(c2)) => if !c1.is_subset(c2) { return false; },
}
}
true
}
pub fn is_superset(&self, other: &Self) -> bool {
other.is_subset(self)
}
}
impl<'a> Iterator for Pairs<'a> {
type Item = (Option<&'a Container>, Option<&'a Container>);
fn next(&mut self) -> Option<Self::Item> {
enum Which { Left, Right, Both, None };
let which = match (self.0.peek(), self.1.peek()) {
(None, None) => Which::None,
(Some(_), None) => Which::Left,
(None, Some(_)) => Which::Right,
(Some(c1), Some(c2)) => match (c1.key, c2.key) {
(key1, key2) if key1 == key2 => Which::Both,
(key1, key2) if key1 < key2 => Which::Left,
(key1, key2) if key1 > key2 => Which::Right,
(_, _) => unreachable!(),
}
};
match which {
Which::Left => Some((self.0.next(), None)),
Which::Right => Some((None, self.1.next())),
Which::Both => Some((self.0.next(), self.1.next())),
Which::None => None,
}
}
}