# Heapq Priority Queue with scoring function # Usage ```toml [dependencies] heapq = "0.1.0" ``` In the code you first need to create an instance with `heaqp::PriorityQueue::new`. It takes a closure that converts your item type `&T` into score type `S: Ord`. Then you can use `push/pop/peek` methods in the same way as `std::collections::BinaryHeap`. # Example ```rust use std::cmp::Reverse; use heapq::PriorityQueue; fn main() { // a score function that returns the length of a string let score_fn = |s: &String| s.len(); // create a new priority queue with the score function let mut queue = PriorityQueue::new(score_fn); // the queue is empty at the beginning assert!(queue.peek().is_none()); // push some items into the queue // the score function is used to calculate the score of each item queue.push("a".to_string()); // score = 1 queue.push("ccc".to_string()); // score = 3 queue.push("bb".to_string()); // score = 2 // you can also push an item with a explicit score queue.push_with_score("b".to_string(), 10); // score = 10 // peek the item with the highest priority assert_eq!(queue.peek(), Some(&"b".to_string())); // pop the item with the highest priority assert_eq!(queue.pop(), Some("b".to_string())); assert_eq!(queue.pop(), Some("ccc".to_string())); assert_eq!(queue.pop(), Some("bb".to_string())); assert_eq!(queue.pop(), Some("a".to_string())); // the queue is empty again assert!(queue.peek().is_none()); // you can also use a reverse order let score_fn = |s: &String| Reverse(s.len()); let mut queue = PriorityQueue::new(score_fn); queue.push("a".to_string()); // score = -1 queue.push("ccc".to_string()); // score = -3 queue.push("bb".to_string()); // score = -2 // remember to use Reverse when pushing an item with a explicit score queue.push_with_score("b".to_string(), Reverse(10)); // score = -10 assert_eq!(queue.peek(), Some(&"a".to_string())); assert_eq!(queue.pop(), Some("a".to_string())); assert_eq!(queue.pop(), Some("bb".to_string())); assert_eq!(queue.pop(), Some("ccc".to_string())); assert_eq!(queue.pop(), Some("b".to_string())); assert!(queue.peek().is_none()); } ```