812 lines
25 KiB
Rust
812 lines
25 KiB
Rust
// Copyright 2013-2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! A priority queue implemented with a binary heap.
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//!
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//! Insertion and popping the largest element have `O(log n)` time complexity.
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//! Checking the largest element is `O(1)`. Converting a vector to a binary heap
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//! can be done in-place, and has `O(n)` complexity. A binary heap can also be
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//! converted to a sorted vector in-place, allowing it to be used for an `O(n
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//! log n)` in-place heapsort.
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//!
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//! # Examples
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//!
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//! This is a larger example that implements [Dijkstra's algorithm][dijkstra]
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//! to solve the [shortest path problem][sssp] on a [directed graph][dir_graph].
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//! It shows how to use `BinaryHeap` with custom types.
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//!
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//! [dijkstra]: http://en.wikipedia.org/wiki/Dijkstra%27s_algorithm
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//! [sssp]: http://en.wikipedia.org/wiki/Shortest_path_problem
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//! [dir_graph]: http://en.wikipedia.org/wiki/Directed_graph
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//!
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//! ```
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//! use std::cmp::Ordering;
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//! use std::collections::BinaryHeap;
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//! use std::usize;
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//!
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//! #[derive(Copy, Clone, Eq, PartialEq)]
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//! struct State {
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//! cost: usize,
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//! position: usize,
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//! }
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//!
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//! // The priority queue depends on `Ord`.
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//! // Explicitly implement the trait so the queue becomes a min-heap
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//! // instead of a max-heap.
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//! impl Ord for State {
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//! fn cmp(&self, other: &State) -> Ordering {
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//! // Notice that the we flip the ordering here
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//! other.cost.cmp(&self.cost)
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//! }
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//! }
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//!
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//! // `PartialOrd` needs to be implemented as well.
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//! impl PartialOrd for State {
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//! fn partial_cmp(&self, other: &State) -> Option<Ordering> {
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//! Some(self.cmp(other))
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//! }
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//! }
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//!
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//! // Each node is represented as an `usize`, for a shorter implementation.
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//! struct Edge {
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//! node: usize,
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//! cost: usize,
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//! }
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//!
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//! // Dijkstra's shortest path algorithm.
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//!
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//! // Start at `start` and use `dist` to track the current shortest distance
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//! // to each node. This implementation isn't memory-efficient as it may leave duplicate
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//! // nodes in the queue. It also uses `usize::MAX` as a sentinel value,
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//! // for a simpler implementation.
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//! fn shortest_path(adj_list: &Vec<Vec<Edge>>, start: usize, goal: usize) -> usize {
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//! // dist[node] = current shortest distance from `start` to `node`
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//! let mut dist: Vec<_> = (0..adj_list.len()).map(|_| usize::MAX).collect();
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//!
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//! let mut heap = BinaryHeap::new();
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//!
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//! // We're at `start`, with a zero cost
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//! dist[start] = 0;
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//! heap.push(State { cost: 0, position: start });
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//!
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//! // Examine the frontier with lower cost nodes first (min-heap)
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//! while let Some(State { cost, position }) = heap.pop() {
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//! // Alternatively we could have continued to find all shortest paths
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//! if position == goal { return cost; }
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//!
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//! // Important as we may have already found a better way
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//! if cost > dist[position] { continue; }
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//!
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//! // For each node we can reach, see if we can find a way with
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//! // a lower cost going through this node
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//! for edge in &adj_list[position] {
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//! let next = State { cost: cost + edge.cost, position: edge.node };
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//!
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//! // If so, add it to the frontier and continue
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//! if next.cost < dist[next.position] {
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//! heap.push(next);
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//! // Relaxation, we have now found a better way
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//! dist[next.position] = next.cost;
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//! }
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//! }
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//! }
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//!
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//! // Goal not reachable
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//! usize::MAX
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//! }
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//!
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//! fn main() {
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//! // This is the directed graph we're going to use.
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//! // The node numbers correspond to the different states,
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//! // and the edge weights symbolize the cost of moving
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//! // from one node to another.
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//! // Note that the edges are one-way.
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//! //
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//! // 7
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//! // +-----------------+
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//! // | |
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//! // v 1 2 | 2
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//! // 0 -----> 1 -----> 3 ---> 4
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//! // | ^ ^ ^
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//! // | | 1 | |
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//! // | | | 3 | 1
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//! // +------> 2 -------+ |
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//! // 10 | |
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//! // +---------------+
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//! //
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//! // The graph is represented as an adjacency list where each index,
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//! // corresponding to a node value, has a list of outgoing edges.
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//! // Chosen for its efficiency.
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//! let graph = vec![
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//! // Node 0
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//! vec![Edge { node: 2, cost: 10 },
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//! Edge { node: 1, cost: 1 }],
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//! // Node 1
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//! vec![Edge { node: 3, cost: 2 }],
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//! // Node 2
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//! vec![Edge { node: 1, cost: 1 },
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//! Edge { node: 3, cost: 3 },
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//! Edge { node: 4, cost: 1 }],
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//! // Node 3
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//! vec![Edge { node: 0, cost: 7 },
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//! Edge { node: 4, cost: 2 }],
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//! // Node 4
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//! vec![]];
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//!
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//! assert_eq!(shortest_path(&graph, 0, 1), 1);
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//! assert_eq!(shortest_path(&graph, 0, 3), 3);
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//! assert_eq!(shortest_path(&graph, 3, 0), 7);
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//! assert_eq!(shortest_path(&graph, 0, 4), 5);
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//! assert_eq!(shortest_path(&graph, 4, 0), usize::MAX);
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//! }
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//! ```
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#![allow(missing_docs)]
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#![stable(feature = "rust1", since = "1.0.0")]
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use core::iter::{FromIterator};
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use core::mem::swap;
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use core::ptr;
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use core::fmt;
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use slice;
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use vec::{self, Vec};
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/// A priority queue implemented with a binary heap.
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///
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/// This will be a max-heap.
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///
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/// It is a logic error for an item to be modified in such a way that the
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/// item's ordering relative to any other item, as determined by the `Ord`
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/// trait, changes while it is in the heap. This is normally only possible
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/// through `Cell`, `RefCell`, global state, I/O, or unsafe code.
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#[stable(feature = "rust1", since = "1.0.0")]
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pub struct BinaryHeap<T> {
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data: Vec<T>,
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<T: Clone> Clone for BinaryHeap<T> {
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fn clone(&self) -> Self {
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BinaryHeap { data: self.data.clone() }
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}
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fn clone_from(&mut self, source: &Self) {
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self.data.clone_from(&source.data);
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<T: Ord> Default for BinaryHeap<T> {
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#[inline]
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fn default() -> BinaryHeap<T> { BinaryHeap::new() }
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}
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#[stable(feature = "binaryheap_debug", since = "1.4.0")]
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impl<T: fmt::Debug + Ord> fmt::Debug for BinaryHeap<T> {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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f.debug_list().entries(self.iter()).finish()
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}
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}
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impl<T: Ord> BinaryHeap<T> {
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/// Creates an empty `BinaryHeap` as a max-heap.
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///
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/// # Examples
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///
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/// ```
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/// use std::collections::BinaryHeap;
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/// let mut heap = BinaryHeap::new();
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/// heap.push(4);
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn new() -> BinaryHeap<T> { BinaryHeap { data: vec![] } }
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/// Creates an empty `BinaryHeap` with a specific capacity.
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/// This preallocates enough memory for `capacity` elements,
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/// so that the `BinaryHeap` does not have to be reallocated
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/// until it contains at least that many values.
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///
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/// # Examples
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///
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/// ```
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/// use std::collections::BinaryHeap;
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/// let mut heap = BinaryHeap::with_capacity(10);
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/// heap.push(4);
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn with_capacity(capacity: usize) -> BinaryHeap<T> {
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BinaryHeap { data: Vec::with_capacity(capacity) }
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}
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/// Creates a `BinaryHeap` from a vector. This is sometimes called
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/// `heapifying` the vector.
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///
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/// # Examples
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///
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/// ```
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/// #![feature(binary_heap_extras)]
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///
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/// use std::collections::BinaryHeap;
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/// let heap = BinaryHeap::from_vec(vec![9, 1, 2, 7, 3, 2]);
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/// ```
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#[unstable(feature = "binary_heap_extras",
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reason = "needs to be audited",
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issue = "28147")]
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pub fn from_vec(vec: Vec<T>) -> BinaryHeap<T> {
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let mut heap = BinaryHeap { data: vec };
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let mut n = heap.len() / 2;
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while n > 0 {
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n -= 1;
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heap.sift_down(n);
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}
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heap
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}
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/// Returns an iterator visiting all values in the underlying vector, in
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/// arbitrary order.
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///
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/// # Examples
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///
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/// ```
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/// #![feature(binary_heap_extras)]
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///
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/// use std::collections::BinaryHeap;
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/// let heap = BinaryHeap::from_vec(vec![1, 2, 3, 4]);
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///
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/// // Print 1, 2, 3, 4 in arbitrary order
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/// for x in heap.iter() {
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/// println!("{}", x);
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/// }
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn iter(&self) -> Iter<T> {
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Iter { iter: self.data.iter() }
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}
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/// Returns the greatest item in the binary heap, or `None` if it is empty.
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///
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/// # Examples
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///
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/// ```
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/// use std::collections::BinaryHeap;
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/// let mut heap = BinaryHeap::new();
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/// assert_eq!(heap.peek(), None);
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///
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/// heap.push(1);
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/// heap.push(5);
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/// heap.push(2);
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/// assert_eq!(heap.peek(), Some(&5));
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///
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn peek(&self) -> Option<&T> {
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self.data.get(0)
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}
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/// Returns the number of elements the binary heap can hold without reallocating.
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///
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/// # Examples
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///
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/// ```
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/// use std::collections::BinaryHeap;
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/// let mut heap = BinaryHeap::with_capacity(100);
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/// assert!(heap.capacity() >= 100);
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/// heap.push(4);
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn capacity(&self) -> usize { self.data.capacity() }
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/// Reserves the minimum capacity for exactly `additional` more elements to be inserted in the
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/// given `BinaryHeap`. Does nothing if the capacity is already sufficient.
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///
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/// Note that the allocator may give the collection more space than it requests. Therefore
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/// capacity can not be relied upon to be precisely minimal. Prefer `reserve` if future
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/// insertions are expected.
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///
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/// # Panics
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///
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/// Panics if the new capacity overflows `usize`.
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///
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/// # Examples
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///
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/// ```
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/// use std::collections::BinaryHeap;
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/// let mut heap = BinaryHeap::new();
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/// heap.reserve_exact(100);
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/// assert!(heap.capacity() >= 100);
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/// heap.push(4);
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn reserve_exact(&mut self, additional: usize) {
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self.data.reserve_exact(additional);
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}
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/// Reserves capacity for at least `additional` more elements to be inserted in the
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/// `BinaryHeap`. The collection may reserve more space to avoid frequent reallocations.
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///
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/// # Panics
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///
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/// Panics if the new capacity overflows `usize`.
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///
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/// # Examples
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///
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/// ```
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/// use std::collections::BinaryHeap;
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/// let mut heap = BinaryHeap::new();
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/// heap.reserve(100);
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/// assert!(heap.capacity() >= 100);
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/// heap.push(4);
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn reserve(&mut self, additional: usize) {
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self.data.reserve(additional);
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}
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/// Discards as much additional capacity as possible.
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn shrink_to_fit(&mut self) {
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self.data.shrink_to_fit();
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}
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/// Removes the greatest item from the binary heap and returns it, or `None` if it
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/// is empty.
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///
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/// # Examples
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///
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/// ```
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/// #![feature(binary_heap_extras)]
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///
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/// use std::collections::BinaryHeap;
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/// let mut heap = BinaryHeap::from_vec(vec![1, 3]);
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///
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/// assert_eq!(heap.pop(), Some(3));
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/// assert_eq!(heap.pop(), Some(1));
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/// assert_eq!(heap.pop(), None);
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn pop(&mut self) -> Option<T> {
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self.data.pop().map(|mut item| {
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if !self.is_empty() {
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swap(&mut item, &mut self.data[0]);
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self.sift_down(0);
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}
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item
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})
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}
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/// Pushes an item onto the binary heap.
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///
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/// # Examples
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///
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/// ```
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/// use std::collections::BinaryHeap;
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/// let mut heap = BinaryHeap::new();
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/// heap.push(3);
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/// heap.push(5);
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/// heap.push(1);
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///
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/// assert_eq!(heap.len(), 3);
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/// assert_eq!(heap.peek(), Some(&5));
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn push(&mut self, item: T) {
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let old_len = self.len();
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self.data.push(item);
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self.sift_up(0, old_len);
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}
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/// Pushes an item onto the binary heap, then pops the greatest item off the queue in
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/// an optimized fashion.
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///
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/// # Examples
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///
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/// ```
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/// #![feature(binary_heap_extras)]
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///
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/// use std::collections::BinaryHeap;
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/// let mut heap = BinaryHeap::new();
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/// heap.push(1);
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/// heap.push(5);
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///
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/// assert_eq!(heap.push_pop(3), 5);
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/// assert_eq!(heap.push_pop(9), 9);
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/// assert_eq!(heap.len(), 2);
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/// assert_eq!(heap.peek(), Some(&3));
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/// ```
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#[unstable(feature = "binary_heap_extras",
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reason = "needs to be audited",
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issue = "28147")]
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pub fn push_pop(&mut self, mut item: T) -> T {
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match self.data.get_mut(0) {
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None => return item,
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Some(top) => if *top > item {
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swap(&mut item, top);
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} else {
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return item;
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},
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}
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self.sift_down(0);
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item
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}
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/// Pops the greatest item off the binary heap, then pushes an item onto the queue in
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/// an optimized fashion. The push is done regardless of whether the binary heap
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/// was empty.
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///
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/// # Examples
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///
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/// ```
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/// #![feature(binary_heap_extras)]
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///
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/// use std::collections::BinaryHeap;
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/// let mut heap = BinaryHeap::new();
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///
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/// assert_eq!(heap.replace(1), None);
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/// assert_eq!(heap.replace(3), Some(1));
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/// assert_eq!(heap.len(), 1);
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/// assert_eq!(heap.peek(), Some(&3));
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/// ```
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#[unstable(feature = "binary_heap_extras",
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reason = "needs to be audited",
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issue = "28147")]
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pub fn replace(&mut self, mut item: T) -> Option<T> {
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if !self.is_empty() {
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swap(&mut item, &mut self.data[0]);
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self.sift_down(0);
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Some(item)
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} else {
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self.push(item);
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None
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}
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}
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/// Consumes the `BinaryHeap` and returns the underlying vector
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/// in arbitrary order.
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///
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/// # Examples
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///
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/// ```
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/// #![feature(binary_heap_extras)]
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///
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/// use std::collections::BinaryHeap;
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/// let heap = BinaryHeap::from_vec(vec![1, 2, 3, 4, 5, 6, 7]);
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/// let vec = heap.into_vec();
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///
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/// // Will print in some order
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/// for x in vec {
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/// println!("{}", x);
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/// }
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/// ```
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#[unstable(feature = "binary_heap_extras",
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reason = "needs to be audited",
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issue = "28147")]
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pub fn into_vec(self) -> Vec<T> { self.data }
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/// Consumes the `BinaryHeap` and returns a vector in sorted
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/// (ascending) order.
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///
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/// # Examples
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///
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/// ```
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/// #![feature(binary_heap_extras)]
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///
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/// use std::collections::BinaryHeap;
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///
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/// let mut heap = BinaryHeap::from_vec(vec![1, 2, 4, 5, 7]);
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/// heap.push(6);
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/// heap.push(3);
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///
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/// let vec = heap.into_sorted_vec();
|
|
/// assert_eq!(vec, [1, 2, 3, 4, 5, 6, 7]);
|
|
/// ```
|
|
#[unstable(feature = "binary_heap_extras",
|
|
reason = "needs to be audited",
|
|
issue = "28147")]
|
|
pub fn into_sorted_vec(mut self) -> Vec<T> {
|
|
let mut end = self.len();
|
|
while end > 1 {
|
|
end -= 1;
|
|
self.data.swap(0, end);
|
|
self.sift_down_range(0, end);
|
|
}
|
|
self.into_vec()
|
|
}
|
|
|
|
// The implementations of sift_up and sift_down use unsafe blocks in
|
|
// order to move an element out of the vector (leaving behind a
|
|
// hole), shift along the others and move the removed element back into the
|
|
// vector at the final location of the hole.
|
|
// The `Hole` type is used to represent this, and make sure
|
|
// the hole is filled back at the end of its scope, even on panic.
|
|
// Using a hole reduces the constant factor compared to using swaps,
|
|
// which involves twice as many moves.
|
|
fn sift_up(&mut self, start: usize, pos: usize) {
|
|
unsafe {
|
|
// Take out the value at `pos` and create a hole.
|
|
let mut hole = Hole::new(&mut self.data, pos);
|
|
|
|
while hole.pos() > start {
|
|
let parent = (hole.pos() - 1) / 2;
|
|
if hole.removed() <= hole.get(parent) { break }
|
|
hole.move_to(parent);
|
|
}
|
|
}
|
|
}
|
|
|
|
fn sift_down_range(&mut self, mut pos: usize, end: usize) {
|
|
let start = pos;
|
|
unsafe {
|
|
let mut hole = Hole::new(&mut self.data, pos);
|
|
let mut child = 2 * pos + 1;
|
|
while child < end {
|
|
let right = child + 1;
|
|
if right < end && !(hole.get(child) > hole.get(right)) {
|
|
child = right;
|
|
}
|
|
hole.move_to(child);
|
|
child = 2 * hole.pos() + 1;
|
|
}
|
|
|
|
pos = hole.pos;
|
|
}
|
|
self.sift_up(start, pos);
|
|
}
|
|
|
|
fn sift_down(&mut self, pos: usize) {
|
|
let len = self.len();
|
|
self.sift_down_range(pos, len);
|
|
}
|
|
|
|
/// Returns the length of the binary heap.
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
pub fn len(&self) -> usize { self.data.len() }
|
|
|
|
/// Checks if the binary heap is empty.
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
pub fn is_empty(&self) -> bool { self.len() == 0 }
|
|
|
|
/// Clears the binary heap, returning an iterator over the removed elements.
|
|
///
|
|
/// The elements are removed in arbitrary order.
|
|
#[inline]
|
|
#[unstable(feature = "drain",
|
|
reason = "matches collection reform specification, \
|
|
waiting for dust to settle",
|
|
issue = "27711")]
|
|
pub fn drain(&mut self) -> Drain<T> {
|
|
Drain { iter: self.data.drain(..) }
|
|
}
|
|
|
|
/// Drops all items from the binary heap.
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
pub fn clear(&mut self) { self.drain(); }
|
|
}
|
|
|
|
/// Hole represents a hole in a slice i.e. an index without valid value
|
|
/// (because it was moved from or duplicated).
|
|
/// In drop, `Hole` will restore the slice by filling the hole
|
|
/// position with the value that was originally removed.
|
|
struct Hole<'a, T: 'a> {
|
|
data: &'a mut [T],
|
|
/// `elt` is always `Some` from new until drop.
|
|
elt: Option<T>,
|
|
pos: usize,
|
|
}
|
|
|
|
impl<'a, T> Hole<'a, T> {
|
|
/// Create a new Hole at index `pos`.
|
|
fn new(data: &'a mut [T], pos: usize) -> Self {
|
|
unsafe {
|
|
let elt = ptr::read(&data[pos]);
|
|
Hole {
|
|
data: data,
|
|
elt: Some(elt),
|
|
pos: pos,
|
|
}
|
|
}
|
|
}
|
|
|
|
#[inline(always)]
|
|
fn pos(&self) -> usize { self.pos }
|
|
|
|
/// Return a reference to the element removed
|
|
#[inline(always)]
|
|
fn removed(&self) -> &T {
|
|
self.elt.as_ref().unwrap()
|
|
}
|
|
|
|
/// Return a reference to the element at `index`.
|
|
///
|
|
/// Panics if the index is out of bounds.
|
|
///
|
|
/// Unsafe because index must not equal pos.
|
|
#[inline(always)]
|
|
unsafe fn get(&self, index: usize) -> &T {
|
|
debug_assert!(index != self.pos);
|
|
&self.data[index]
|
|
}
|
|
|
|
/// Move hole to new location
|
|
///
|
|
/// Unsafe because index must not equal pos.
|
|
#[inline(always)]
|
|
unsafe fn move_to(&mut self, index: usize) {
|
|
debug_assert!(index != self.pos);
|
|
let index_ptr: *const _ = &self.data[index];
|
|
let hole_ptr = &mut self.data[self.pos];
|
|
ptr::copy_nonoverlapping(index_ptr, hole_ptr, 1);
|
|
self.pos = index;
|
|
}
|
|
}
|
|
|
|
impl<'a, T> Drop for Hole<'a, T> {
|
|
fn drop(&mut self) {
|
|
// fill the hole again
|
|
unsafe {
|
|
let pos = self.pos;
|
|
ptr::write(&mut self.data[pos], self.elt.take().unwrap());
|
|
}
|
|
}
|
|
}
|
|
|
|
/// `BinaryHeap` iterator.
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
pub struct Iter <'a, T: 'a> {
|
|
iter: slice::Iter<'a, T>,
|
|
}
|
|
|
|
// FIXME(#19839) Remove in favor of `#[derive(Clone)]`
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<'a, T> Clone for Iter<'a, T> {
|
|
fn clone(&self) -> Iter<'a, T> {
|
|
Iter { iter: self.iter.clone() }
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<'a, T> Iterator for Iter<'a, T> {
|
|
type Item = &'a T;
|
|
|
|
#[inline]
|
|
fn next(&mut self) -> Option<&'a T> { self.iter.next() }
|
|
|
|
#[inline]
|
|
fn size_hint(&self) -> (usize, Option<usize>) { self.iter.size_hint() }
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<'a, T> DoubleEndedIterator for Iter<'a, T> {
|
|
#[inline]
|
|
fn next_back(&mut self) -> Option<&'a T> { self.iter.next_back() }
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<'a, T> ExactSizeIterator for Iter<'a, T> {}
|
|
|
|
/// An iterator that moves out of a `BinaryHeap`.
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
pub struct IntoIter<T> {
|
|
iter: vec::IntoIter<T>,
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<T> Iterator for IntoIter<T> {
|
|
type Item = T;
|
|
|
|
#[inline]
|
|
fn next(&mut self) -> Option<T> { self.iter.next() }
|
|
|
|
#[inline]
|
|
fn size_hint(&self) -> (usize, Option<usize>) { self.iter.size_hint() }
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<T> DoubleEndedIterator for IntoIter<T> {
|
|
#[inline]
|
|
fn next_back(&mut self) -> Option<T> { self.iter.next_back() }
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<T> ExactSizeIterator for IntoIter<T> {}
|
|
|
|
/// An iterator that drains a `BinaryHeap`.
|
|
#[unstable(feature = "drain", reason = "recent addition", issue = "27711")]
|
|
pub struct Drain<'a, T: 'a> {
|
|
iter: vec::Drain<'a, T>,
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<'a, T: 'a> Iterator for Drain<'a, T> {
|
|
type Item = T;
|
|
|
|
#[inline]
|
|
fn next(&mut self) -> Option<T> { self.iter.next() }
|
|
|
|
#[inline]
|
|
fn size_hint(&self) -> (usize, Option<usize>) { self.iter.size_hint() }
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<'a, T: 'a> DoubleEndedIterator for Drain<'a, T> {
|
|
#[inline]
|
|
fn next_back(&mut self) -> Option<T> { self.iter.next_back() }
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<'a, T: 'a> ExactSizeIterator for Drain<'a, T> {}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<T: Ord> FromIterator<T> for BinaryHeap<T> {
|
|
fn from_iter<I: IntoIterator<Item=T>>(iter: I) -> BinaryHeap<T> {
|
|
BinaryHeap::from_vec(iter.into_iter().collect())
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<T: Ord> IntoIterator for BinaryHeap<T> {
|
|
type Item = T;
|
|
type IntoIter = IntoIter<T>;
|
|
|
|
/// Creates a consuming iterator, that is, one that moves each value out of
|
|
/// the binary heap in arbitrary order. The binary heap cannot be used
|
|
/// after calling this.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// #![feature(binary_heap_extras)]
|
|
///
|
|
/// use std::collections::BinaryHeap;
|
|
/// let heap = BinaryHeap::from_vec(vec![1, 2, 3, 4]);
|
|
///
|
|
/// // Print 1, 2, 3, 4 in arbitrary order
|
|
/// for x in heap.into_iter() {
|
|
/// // x has type i32, not &i32
|
|
/// println!("{}", x);
|
|
/// }
|
|
/// ```
|
|
fn into_iter(self) -> IntoIter<T> {
|
|
IntoIter { iter: self.data.into_iter() }
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<'a, T> IntoIterator for &'a BinaryHeap<T> where T: Ord {
|
|
type Item = &'a T;
|
|
type IntoIter = Iter<'a, T>;
|
|
|
|
fn into_iter(self) -> Iter<'a, T> {
|
|
self.iter()
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<T: Ord> Extend<T> for BinaryHeap<T> {
|
|
fn extend<I: IntoIterator<Item=T>>(&mut self, iterable: I) {
|
|
let iter = iterable.into_iter();
|
|
let (lower, _) = iter.size_hint();
|
|
|
|
self.reserve(lower);
|
|
|
|
for elem in iter {
|
|
self.push(elem);
|
|
}
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "extend_ref", since = "1.2.0")]
|
|
impl<'a, T: 'a + Ord + Copy> Extend<&'a T> for BinaryHeap<T> {
|
|
fn extend<I: IntoIterator<Item=&'a T>>(&mut self, iter: I) {
|
|
self.extend(iter.into_iter().cloned());
|
|
}
|
|
}
|