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use std::{cmp::Ordering, collections::BinaryHeap};
use crate::PriorityQueue;
pub(crate) struct Item<K, T> {
key: K,
value: T,
}
impl<K: Ord + std::fmt::Debug, T: std::fmt::Debug> std::fmt::Debug for Item<K, T> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(f, "({:?}: {:?})", self.key, self.value)
}
}
impl<K: Ord + std::fmt::Debug, T: std::fmt::Debug> std::fmt::Debug for PriorityQueue<K, T> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
std::fmt::Debug::fmt(&self.0, f)
}
}
impl<K: Ord, T> PartialEq<Self> for Item<K, T> {
fn eq(&self, other: &Self) -> bool {
Ord::cmp(self, other).is_eq()
}
}
impl<K: Ord, T> Eq for Item<K, T> {}
impl<K: Ord, T> PartialOrd<Self> for Item<K, T> {
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
Ord::cmp(self, other).into()
}
}
impl<K: Ord, T> Ord for Item<K, T> {
fn cmp(&self, other: &Self) -> Ordering {
self.key.cmp(&other.key)
}
}
impl<K, T> Clone for Item<K, T>
where
K: Clone,
T: Clone,
{
fn clone(&self) -> Self {
Item {
key: self.key.clone(),
value: self.value.clone(),
}
}
}
impl<K, T> Clone for PriorityQueue<K, T>
where
K: Clone + Ord,
T: Clone,
{
fn clone(&self) -> Self {
Self(self.0.clone())
}
}
impl<K: Ord, T> PriorityQueue<K, T> {
/// Create a new instance.
pub fn new() -> Self {
PriorityQueue(Default::default())
}
/// Insert `value` so that it is ordered according to `key`.
pub fn insert(&mut self, key: K, value: T) {
self.0.push(Item { key, value });
}
/// Pop the highest-priority item value off the queue.
pub fn pop_value(&mut self) -> Option<T> {
self.0.pop().map(|t| t.value)
}
/// Pop the highest-priority item key and value off the queue.
pub fn pop(&mut self) -> Option<(K, T)> {
self.0.pop().map(|t| (t.key, t.value))
}
/// Iterate all items ordered from highest to lowest priority.
pub fn iter_unordered(&self) -> impl Iterator<Item = &T> {
self.0.iter().map(|t| &t.value)
}
/// Turn this instance into an iterator over its keys and values in arbitrary order.
pub fn into_iter_unordered(self) -> impl Iterator<Item = (K, T)> {
self.0.into_vec().into_iter().map(|item| (item.key, item.value))
}
/// Return true if the queue is empty.
pub fn is_empty(&self) -> bool {
self.0.is_empty()
}
/// Returns the greatest item `(K, T)` tuple, as ordered by `K`, if the queue is not empty, without removing it.
pub fn peek(&self) -> Option<(&K, &T)> {
self.0.peek().map(|e| (&e.key, &e.value))
}
/// Drop all items from the queue, without changing its capacity.
pub fn clear(&mut self) {
self.0.clear()
}
}
impl<K: Ord, T> FromIterator<(K, T)> for PriorityQueue<K, T> {
fn from_iter<I: IntoIterator<Item = (K, T)>>(iter: I) -> Self {
let mut q = PriorityQueue(BinaryHeap::new());
for (k, v) in iter {
q.insert(k, v);
}
q
}
}
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