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use alloc::collections::btree_map;
use core::iter::Peekable;
use crate::RoaringBitmap;
use crate::RoaringTreemap;
pub(crate) struct Pairs<'a>(
Peekable<btree_map::Iter<'a, u32, RoaringBitmap>>,
Peekable<btree_map::Iter<'a, u32, RoaringBitmap>>,
);
impl RoaringTreemap {
pub(crate) fn pairs<'a>(&'a self, other: &'a RoaringTreemap) -> Pairs<'a> {
Pairs(self.map.iter().peekable(), other.map.iter().peekable())
}
/// Returns true if the set has no elements in common with other. This is equivalent to
/// checking for an empty intersection.
///
/// # Examples
///
/// ```rust
/// use roaring::RoaringTreemap;
///
/// let mut rb1 = RoaringTreemap::new();
/// let mut rb2 = RoaringTreemap::new();
///
/// rb1.insert(1);
///
/// assert_eq!(rb1.is_disjoint(&rb2), true);
///
/// rb2.insert(1);
///
/// assert_eq!(rb1.is_disjoint(&rb2), false);
///
/// ```
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()))
}
/// Returns `true` if this set is a subset of `other`.
///
/// # Examples
///
/// ```rust
/// use roaring::RoaringTreemap;
///
/// let mut rb1 = RoaringTreemap::new();
/// let mut rb2 = RoaringTreemap::new();
///
/// rb1.insert(1);
///
/// assert_eq!(rb1.is_subset(&rb2), false);
///
/// rb2.insert(1);
///
/// assert_eq!(rb1.is_subset(&rb2), true);
///
/// rb1.insert(2);
///
/// assert_eq!(rb1.is_subset(&rb2), false);
/// ```
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
}
/// Returns `true` if this set is a superset of `other`.
///
/// # Examples
///
/// ```rust
/// use roaring::RoaringTreemap;
///
/// let mut rb1 = RoaringTreemap::new();
/// let mut rb2 = RoaringTreemap::new();
///
/// rb1.insert(1);
///
/// assert_eq!(rb2.is_superset(&rb1), false);
///
/// rb2.insert(1);
///
/// assert_eq!(rb2.is_superset(&rb1), true);
///
/// rb1.insert(2);
///
/// assert_eq!(rb2.is_superset(&rb1), false);
/// ```
pub fn is_superset(&self, other: &Self) -> bool {
other.is_subset(self)
}
}
impl<'a> Iterator for Pairs<'a> {
type Item = (Option<&'a RoaringBitmap>, Option<&'a RoaringBitmap>);
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 (c1.0, c2.0) {
(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().map(|e| e.1), None)),
Which::Right => Some((None, self.1.next().map(|e| e.1))),
Which::Both => Some((self.0.next().map(|e| e.1), self.1.next().map(|e| e.1))),
Which::None => None,
}
}
}