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use std::num::NonZeroUsize;
use crate::to_right;
use super::*;
/// an iterator over the intersection of two [`crate::PrefixSet`]s in lexicographic order.
pub struct Intersection<'a, P, L, R> {
pub(super) table_l: &'a Table<P, L>,
pub(super) table_r: &'a Table<P, R>,
pub(super) nodes: Vec<IntersectionIndex>,
}
/// an iterator over the intersection of two [`crate::PrefixSet`]s in lexicographic order, yielding
/// mutable references to all elements.
pub struct IntersectionMut<'a, P, L, R> {
pub(super) table_l: &'a Table<P, L>,
pub(super) table_r: &'a Table<P, R>,
pub(super) nodes: Vec<IntersectionIndex>,
}
impl<'a, P, L, R> IntersectionMut<'a, P, L, R> {
/// Safety:
/// 1. Table_l must come from a `TrieViewMut` and satisfy the conditions in `TrieViewMut::new`.
/// 2. Table_r must come from a `TrieViewMut` and satisfy the conditions in `TrieViewMut::new`.
/// 3. Table_l and Table_r must be distinct. This is implicitly given by the two rules above.
unsafe fn new(
table_l: &'a Table<P, L>,
table_r: &'a Table<P, R>,
nodes: Vec<IntersectionIndex>,
) -> Self {
Self {
table_l,
table_r,
nodes,
}
}
}
pub(super) enum IntersectionIndex {
Both(usize, usize),
FirstA(usize, usize),
FirstB(usize, usize),
}
impl<'a, P, L> TrieView<'a, P, L>
where
P: Prefix,
{
/// Iterate over the union of both Views. Each element will yield a reference to the prefix and
/// the value stored in `self` and `other` (if the prefix is in both views).
///
/// ```
/// # use prefix_trie::*;
/// # #[cfg(feature = "ipnet")]
/// macro_rules! net { ($x:literal) => {$x.parse::<ipnet::Ipv4Net>().unwrap()}; }
///
/// # #[cfg(feature = "ipnet")]
/// # {
/// let mut map_a: PrefixMap<ipnet::Ipv4Net, usize> = PrefixMap::from_iter([
/// (net!("192.168.0.0/20"), 1),
/// (net!("192.168.0.0/22"), 2),
/// (net!("192.168.0.0/24"), 3),
/// (net!("192.168.2.0/23"), 4),
/// ]);
/// let mut map_b: PrefixMap<ipnet::Ipv4Net, &'static str> = PrefixMap::from_iter([
/// (net!("192.168.0.0/20"), "a"),
/// (net!("192.168.0.0/22"), "b"),
/// (net!("192.168.0.0/23"), "c"),
/// (net!("192.168.0.0/24"), "d"),
/// (net!("192.168.2.0/24"), "e"),
/// ]);
/// let sub_a = map_a.view_at(net!("192.168.0.0/22")).unwrap();
/// let sub_b = map_b.view_at(net!("192.168.0.0/22")).unwrap();
/// assert_eq!(
/// sub_a.intersection(&sub_b).collect::<Vec<_>>(),
/// vec![
/// (&net!("192.168.0.0/22"), &2, &"b"),
/// (&net!("192.168.0.0/24"), &3, &"d"),
/// ]
/// );
/// # }
/// ```
pub fn intersection<R>(
&self,
other: &'a impl AsView<P = P, T = R>,
) -> Intersection<'a, P, L, R> {
let other = other.view();
Intersection {
table_l: self.table,
table_r: other.table,
nodes: Vec::from_iter(next_indices(
self.table,
other.table,
Some(self.loc.idx()),
Some(other.loc.idx()),
)),
}
}
}
impl<P, L> TrieViewMut<'_, P, L>
where
P: Prefix,
{
/// Iterate over the union of both Views. Each element will yield a reference to the prefix and
/// mutable references to the values stored in `self` and `other` (if the prefix is in both
/// views).
///
/// ```
/// # use prefix_trie::*;
/// # use prefix_trie::trieview::UnionItem;
/// # #[cfg(feature = "ipnet")]
/// macro_rules! net { ($x:literal) => {$x.parse::<ipnet::Ipv4Net>().unwrap()}; }
///
/// # #[cfg(feature = "ipnet")]
/// # {
/// let mut map_a: PrefixMap<ipnet::Ipv4Net, usize> = PrefixMap::from_iter([
/// (net!("192.168.0.0/20"), 1),
/// (net!("192.168.0.0/22"), 2),
/// (net!("192.168.0.0/24"), 3),
/// (net!("192.168.2.0/23"), 4),
/// ]);
/// let mut map_b: PrefixMap<ipnet::Ipv4Net, usize> = PrefixMap::from_iter([
/// (net!("192.168.0.0/22"), 10),
/// (net!("192.168.0.0/23"), 20),
/// (net!("192.168.2.0/24"), 30),
/// ]);
///
/// // Modify the two maps by adding their values for elements of the same prefix.
/// for (_, l, r) in map_a.view_mut().intersection_mut(&mut map_b) {
/// *l += *r;
/// *r = *l;
/// }
///
/// assert_eq!(
/// map_a.into_iter().collect::<Vec<_>>(),
/// vec![
/// (net!("192.168.0.0/20"), 1),
/// (net!("192.168.0.0/22"), 12),
/// (net!("192.168.0.0/24"), 3),
/// (net!("192.168.2.0/23"), 4),
/// ],
/// );
/// assert_eq!(
/// map_b.into_iter().collect::<Vec<_>>(),
/// vec![
/// (net!("192.168.0.0/22"), 12),
/// (net!("192.168.0.0/23"), 20),
/// (net!("192.168.2.0/24"), 30),
/// ],
/// );
/// # }
/// ```
pub fn intersection_mut<'b, R>(
&'b mut self,
other: impl AsViewMut<'b, P, R>,
) -> IntersectionMut<'b, P, L, R> {
let other = other.view_mut();
let nodes = Vec::from_iter(next_indices(
self.table,
other.table,
Some(self.loc.idx()),
Some(other.loc.idx()),
));
// Safety: Both `self` and `other` are `TrieViewMut`s, and must adhere to the safety
// constraints in `TrieViewMut::new`.
unsafe { IntersectionMut::new(self.table, other.table, nodes) }
}
}
impl<'a, P: Prefix, L, R> Iterator for Intersection<'a, P, L, R> {
type Item = (&'a P, &'a L, &'a R);
fn next(&mut self) -> Option<Self::Item> {
while let Some(cur) = self.nodes.pop() {
match cur {
IntersectionIndex::Both(l, r) => {
let node_l = &self.table_l[l];
let node_r = &self.table_r[r];
self.nodes.extend(next_indices(
self.table_l,
self.table_r,
node_l.right,
node_r.right,
));
self.nodes.extend(next_indices(
self.table_l,
self.table_r,
node_l.left,
node_r.left,
));
if let (Some(left), Some(right)) =
(node_l.value.as_ref(), node_r.value.as_ref())
{
return Some((&node_l.prefix, left, right));
}
}
IntersectionIndex::FirstA(l, r) => {
let node_l = &self.table_l[l];
self.nodes.extend(next_indices_first_a(
self.table_l,
self.table_r,
l,
node_l.left,
node_l.right,
r,
));
}
IntersectionIndex::FirstB(l, r) => {
let node_r = &self.table_r[r];
self.nodes.extend(next_indices_first_b(
self.table_l,
self.table_r,
l,
r,
node_r.left,
node_r.right,
));
}
}
}
None
}
}
impl<'a, P: Prefix, L, R> Iterator for IntersectionMut<'a, P, L, R> {
type Item = (&'a P, &'a mut L, &'a mut R);
fn next(&mut self) -> Option<Self::Item> {
// safety: map is a tree. Every node is visited exactly once during the iteration
// (self.nodes is not public). Therefore, each in each iteration of this loop (also between
// multiple calls to `next`), the index `cur` is different to any of the earlier
// iterations. It is therefore safe to extend the lifetime of the elements to 'a (which is
// the lifetime for which `self` has an exclusive reference over the map).
while let Some(cur) = self.nodes.pop() {
match cur {
IntersectionIndex::Both(l, r) => {
let node_l = &self.table_l[l];
let node_r = &self.table_r[r];
self.nodes.extend(next_indices(
self.table_l,
self.table_r,
node_l.right,
node_r.right,
));
self.nodes.extend(next_indices(
self.table_l,
self.table_r,
node_l.left,
node_r.left,
));
let node_l = unsafe { self.table_l.get_mut(l) };
let node_r = unsafe { self.table_r.get_mut(r) };
if let (Some(left), Some(right)) =
(node_l.value.as_mut(), node_r.value.as_mut())
{
return Some((&node_l.prefix, left, right));
}
}
IntersectionIndex::FirstA(l, r) => {
let node_l = &self.table_l[l];
self.nodes.extend(next_indices_first_a(
self.table_l,
self.table_r,
l,
node_l.left,
node_l.right,
r,
));
}
IntersectionIndex::FirstB(l, r) => {
let node_r = &self.table_r[r];
self.nodes.extend(next_indices_first_b(
self.table_l,
self.table_r,
l,
r,
node_r.left,
node_r.right,
));
}
}
}
None
}
}
fn next_indices<'a, P: Prefix, L, R>(
table_l: &'a Table<P, L>,
table_r: &'a Table<P, R>,
node_l: Option<impl Into<usize>>,
node_r: Option<impl Into<usize>>,
) -> Option<IntersectionIndex> {
match (node_l.map(|x| x.into()), node_r.map(|x| x.into())) {
(None, Some(_)) => None,
(Some(_), None) => None,
(Some(a), Some(b)) => {
let p_a = &table_l[a].prefix;
let p_b = &table_r[b].prefix;
if p_a.prefix_len() == p_b.prefix_len() {
match p_a.mask().cmp(&p_b.mask()) {
std::cmp::Ordering::Equal => Some(IntersectionIndex::Both(a, b)),
_ => None,
}
} else if p_a.contains(p_b) {
Some(IntersectionIndex::FirstA(a, b))
} else if p_b.contains(p_a) {
Some(IntersectionIndex::FirstB(a, b))
} else {
None
}
}
_ => None,
}
}
fn next_indices_first_a<'a, P: Prefix, L, R>(
table_l: &'a Table<P, L>,
table_r: &'a Table<P, R>,
l: usize,
ll: Option<NonZeroUsize>,
lr: Option<NonZeroUsize>,
r: usize,
) -> Option<IntersectionIndex> {
match (ll, lr) {
(None, None) => None,
(None, Some(lr)) => next_indices(table_l, table_r, Some(lr), Some(r)),
(Some(ll), None) => next_indices(table_l, table_r, Some(ll), Some(r)),
(Some(ll), Some(lr)) => {
if to_right(&table_l[l].prefix, &table_r[r].prefix) {
next_indices(table_l, table_r, Some(lr), Some(r))
} else {
next_indices(table_l, table_r, Some(ll), Some(r))
}
}
}
}
fn next_indices_first_b<'a, P: Prefix, L, R>(
table_l: &'a Table<P, L>,
table_r: &'a Table<P, R>,
l: usize,
r: usize,
rl: Option<NonZeroUsize>,
rr: Option<NonZeroUsize>,
) -> Option<IntersectionIndex> {
match (rl, rr) {
(None, None) => None,
(None, Some(rr)) => next_indices(table_l, table_r, Some(l), Some(rr)),
(Some(rl), None) => next_indices(table_l, table_r, Some(l), Some(rl)),
(Some(rl), Some(rr)) => {
if to_right(&table_r[r].prefix, &table_l[l].prefix) {
next_indices(table_l, table_r, Some(l), Some(rr))
} else {
next_indices(table_l, table_r, Some(l), Some(rl))
}
}
}
}