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1 | // Copyright 2013-2014 The Rust Project Developers. See the COPYRIGHT |
2 | // file at the top-level directory of this distribution and at | |
3 | // http://rust-lang.org/COPYRIGHT. | |
4 | // | |
5 | // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or | |
6 | // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license | |
7 | // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your | |
8 | // option. This file may not be copied, modified, or distributed | |
9 | // except according to those terms. | |
10 | ||
11 | //! A priority queue implemented with a binary heap. | |
12 | //! | |
62682a34 SL |
13 | //! Insertion and popping the largest element have `O(log n)` time complexity. |
14 | //! Checking the largest element is `O(1)`. Converting a vector to a binary heap | |
15 | //! can be done in-place, and has `O(n)` complexity. A binary heap can also be | |
16 | //! converted to a sorted vector in-place, allowing it to be used for an `O(n | |
17 | //! log n)` in-place heapsort. | |
1a4d82fc JJ |
18 | //! |
19 | //! # Examples | |
20 | //! | |
21 | //! This is a larger example that implements [Dijkstra's algorithm][dijkstra] | |
22 | //! to solve the [shortest path problem][sssp] on a [directed graph][dir_graph]. | |
23 | //! It shows how to use `BinaryHeap` with custom types. | |
24 | //! | |
25 | //! [dijkstra]: http://en.wikipedia.org/wiki/Dijkstra%27s_algorithm | |
26 | //! [sssp]: http://en.wikipedia.org/wiki/Shortest_path_problem | |
27 | //! [dir_graph]: http://en.wikipedia.org/wiki/Directed_graph | |
28 | //! | |
29 | //! ``` | |
30 | //! use std::cmp::Ordering; | |
31 | //! use std::collections::BinaryHeap; | |
85aaf69f | 32 | //! use std::usize; |
1a4d82fc | 33 | //! |
c34b1796 | 34 | //! #[derive(Copy, Clone, Eq, PartialEq)] |
1a4d82fc | 35 | //! struct State { |
85aaf69f SL |
36 | //! cost: usize, |
37 | //! position: usize, | |
1a4d82fc JJ |
38 | //! } |
39 | //! | |
40 | //! // The priority queue depends on `Ord`. | |
41 | //! // Explicitly implement the trait so the queue becomes a min-heap | |
42 | //! // instead of a max-heap. | |
43 | //! impl Ord for State { | |
44 | //! fn cmp(&self, other: &State) -> Ordering { | |
45 | //! // Notice that the we flip the ordering here | |
46 | //! other.cost.cmp(&self.cost) | |
47 | //! } | |
48 | //! } | |
49 | //! | |
50 | //! // `PartialOrd` needs to be implemented as well. | |
51 | //! impl PartialOrd for State { | |
52 | //! fn partial_cmp(&self, other: &State) -> Option<Ordering> { | |
53 | //! Some(self.cmp(other)) | |
54 | //! } | |
55 | //! } | |
56 | //! | |
85aaf69f | 57 | //! // Each node is represented as an `usize`, for a shorter implementation. |
1a4d82fc | 58 | //! struct Edge { |
85aaf69f SL |
59 | //! node: usize, |
60 | //! cost: usize, | |
1a4d82fc JJ |
61 | //! } |
62 | //! | |
63 | //! // Dijkstra's shortest path algorithm. | |
64 | //! | |
65 | //! // Start at `start` and use `dist` to track the current shortest distance | |
66 | //! // to each node. This implementation isn't memory-efficient as it may leave duplicate | |
85aaf69f | 67 | //! // nodes in the queue. It also uses `usize::MAX` as a sentinel value, |
1a4d82fc | 68 | //! // for a simpler implementation. |
9cc50fc6 | 69 | //! fn shortest_path(adj_list: &Vec<Vec<Edge>>, start: usize, goal: usize) -> Option<usize> { |
1a4d82fc | 70 | //! // dist[node] = current shortest distance from `start` to `node` |
85aaf69f | 71 | //! let mut dist: Vec<_> = (0..adj_list.len()).map(|_| usize::MAX).collect(); |
1a4d82fc JJ |
72 | //! |
73 | //! let mut heap = BinaryHeap::new(); | |
74 | //! | |
75 | //! // We're at `start`, with a zero cost | |
76 | //! dist[start] = 0; | |
77 | //! heap.push(State { cost: 0, position: start }); | |
78 | //! | |
79 | //! // Examine the frontier with lower cost nodes first (min-heap) | |
80 | //! while let Some(State { cost, position }) = heap.pop() { | |
81 | //! // Alternatively we could have continued to find all shortest paths | |
9cc50fc6 | 82 | //! if position == goal { return Some(cost); } |
1a4d82fc JJ |
83 | //! |
84 | //! // Important as we may have already found a better way | |
85 | //! if cost > dist[position] { continue; } | |
86 | //! | |
87 | //! // For each node we can reach, see if we can find a way with | |
88 | //! // a lower cost going through this node | |
62682a34 | 89 | //! for edge in &adj_list[position] { |
1a4d82fc JJ |
90 | //! let next = State { cost: cost + edge.cost, position: edge.node }; |
91 | //! | |
92 | //! // If so, add it to the frontier and continue | |
93 | //! if next.cost < dist[next.position] { | |
94 | //! heap.push(next); | |
95 | //! // Relaxation, we have now found a better way | |
96 | //! dist[next.position] = next.cost; | |
97 | //! } | |
98 | //! } | |
99 | //! } | |
100 | //! | |
101 | //! // Goal not reachable | |
9cc50fc6 | 102 | //! None |
1a4d82fc JJ |
103 | //! } |
104 | //! | |
105 | //! fn main() { | |
106 | //! // This is the directed graph we're going to use. | |
107 | //! // The node numbers correspond to the different states, | |
108 | //! // and the edge weights symbolize the cost of moving | |
109 | //! // from one node to another. | |
110 | //! // Note that the edges are one-way. | |
111 | //! // | |
112 | //! // 7 | |
113 | //! // +-----------------+ | |
114 | //! // | | | |
e9174d1e | 115 | //! // v 1 2 | 2 |
1a4d82fc JJ |
116 | //! // 0 -----> 1 -----> 3 ---> 4 |
117 | //! // | ^ ^ ^ | |
118 | //! // | | 1 | | | |
119 | //! // | | | 3 | 1 | |
120 | //! // +------> 2 -------+ | | |
121 | //! // 10 | | | |
122 | //! // +---------------+ | |
123 | //! // | |
124 | //! // The graph is represented as an adjacency list where each index, | |
125 | //! // corresponding to a node value, has a list of outgoing edges. | |
126 | //! // Chosen for its efficiency. | |
127 | //! let graph = vec![ | |
128 | //! // Node 0 | |
129 | //! vec![Edge { node: 2, cost: 10 }, | |
130 | //! Edge { node: 1, cost: 1 }], | |
131 | //! // Node 1 | |
132 | //! vec![Edge { node: 3, cost: 2 }], | |
133 | //! // Node 2 | |
134 | //! vec![Edge { node: 1, cost: 1 }, | |
135 | //! Edge { node: 3, cost: 3 }, | |
136 | //! Edge { node: 4, cost: 1 }], | |
137 | //! // Node 3 | |
138 | //! vec![Edge { node: 0, cost: 7 }, | |
139 | //! Edge { node: 4, cost: 2 }], | |
140 | //! // Node 4 | |
141 | //! vec![]]; | |
142 | //! | |
9cc50fc6 SL |
143 | //! assert_eq!(shortest_path(&graph, 0, 1), Some(1)); |
144 | //! assert_eq!(shortest_path(&graph, 0, 3), Some(3)); | |
145 | //! assert_eq!(shortest_path(&graph, 3, 0), Some(7)); | |
146 | //! assert_eq!(shortest_path(&graph, 0, 4), Some(5)); | |
147 | //! assert_eq!(shortest_path(&graph, 4, 0), None); | |
1a4d82fc JJ |
148 | //! } |
149 | //! ``` | |
150 | ||
151 | #![allow(missing_docs)] | |
85aaf69f | 152 | #![stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 153 | |
9e0c209e SL |
154 | use core::ops::{Deref, DerefMut}; |
155 | use core::iter::{FromIterator, FusedIterator}; | |
d9579d0f | 156 | use core::mem::swap; |
a7813a04 | 157 | use core::mem::size_of; |
1a4d82fc | 158 | use core::ptr; |
e9174d1e | 159 | use core::fmt; |
1a4d82fc JJ |
160 | |
161 | use slice; | |
162 | use vec::{self, Vec}; | |
163 | ||
a7813a04 XL |
164 | use super::SpecExtend; |
165 | ||
1a4d82fc JJ |
166 | /// A priority queue implemented with a binary heap. |
167 | /// | |
168 | /// This will be a max-heap. | |
c34b1796 AL |
169 | /// |
170 | /// It is a logic error for an item to be modified in such a way that the | |
171 | /// item's ordering relative to any other item, as determined by the `Ord` | |
172 | /// trait, changes while it is in the heap. This is normally only possible | |
173 | /// through `Cell`, `RefCell`, global state, I/O, or unsafe code. | |
54a0048b SL |
174 | /// |
175 | /// # Examples | |
176 | /// | |
177 | /// ``` | |
178 | /// use std::collections::BinaryHeap; | |
179 | /// | |
180 | /// // Type inference lets us omit an explicit type signature (which | |
181 | /// // would be `BinaryHeap<i32>` in this example). | |
182 | /// let mut heap = BinaryHeap::new(); | |
183 | /// | |
184 | /// // We can use peek to look at the next item in the heap. In this case, | |
185 | /// // there's no items in there yet so we get None. | |
186 | /// assert_eq!(heap.peek(), None); | |
187 | /// | |
188 | /// // Let's add some scores... | |
189 | /// heap.push(1); | |
190 | /// heap.push(5); | |
191 | /// heap.push(2); | |
192 | /// | |
193 | /// // Now peek shows the most important item in the heap. | |
194 | /// assert_eq!(heap.peek(), Some(&5)); | |
195 | /// | |
196 | /// // We can check the length of a heap. | |
197 | /// assert_eq!(heap.len(), 3); | |
198 | /// | |
199 | /// // We can iterate over the items in the heap, although they are returned in | |
200 | /// // a random order. | |
201 | /// for x in &heap { | |
202 | /// println!("{}", x); | |
203 | /// } | |
204 | /// | |
205 | /// // If we instead pop these scores, they should come back in order. | |
206 | /// assert_eq!(heap.pop(), Some(5)); | |
207 | /// assert_eq!(heap.pop(), Some(2)); | |
208 | /// assert_eq!(heap.pop(), Some(1)); | |
209 | /// assert_eq!(heap.pop(), None); | |
210 | /// | |
211 | /// // We can clear the heap of any remaining items. | |
212 | /// heap.clear(); | |
213 | /// | |
214 | /// // The heap should now be empty. | |
215 | /// assert!(heap.is_empty()) | |
216 | /// ``` | |
85aaf69f | 217 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
218 | pub struct BinaryHeap<T> { |
219 | data: Vec<T>, | |
220 | } | |
221 | ||
3157f602 XL |
222 | /// A container object that represents the result of the [`peek_mut()`] method |
223 | /// on `BinaryHeap`. See its documentation for details. | |
224 | /// | |
225 | /// [`peek_mut()`]: struct.BinaryHeap.html#method.peek_mut | |
5bcae85e | 226 | #[stable(feature = "binary_heap_peek_mut", since = "1.12.0")] |
3157f602 XL |
227 | pub struct PeekMut<'a, T: 'a + Ord> { |
228 | heap: &'a mut BinaryHeap<T> | |
229 | } | |
230 | ||
5bcae85e | 231 | #[stable(feature = "binary_heap_peek_mut", since = "1.12.0")] |
3157f602 XL |
232 | impl<'a, T: Ord> Drop for PeekMut<'a, T> { |
233 | fn drop(&mut self) { | |
234 | self.heap.sift_down(0); | |
235 | } | |
236 | } | |
237 | ||
5bcae85e | 238 | #[stable(feature = "binary_heap_peek_mut", since = "1.12.0")] |
3157f602 XL |
239 | impl<'a, T: Ord> Deref for PeekMut<'a, T> { |
240 | type Target = T; | |
241 | fn deref(&self) -> &T { | |
242 | &self.heap.data[0] | |
243 | } | |
244 | } | |
245 | ||
5bcae85e | 246 | #[stable(feature = "binary_heap_peek_mut", since = "1.12.0")] |
3157f602 XL |
247 | impl<'a, T: Ord> DerefMut for PeekMut<'a, T> { |
248 | fn deref_mut(&mut self) -> &mut T { | |
249 | &mut self.heap.data[0] | |
250 | } | |
251 | } | |
252 | ||
b039eaaf SL |
253 | #[stable(feature = "rust1", since = "1.0.0")] |
254 | impl<T: Clone> Clone for BinaryHeap<T> { | |
255 | fn clone(&self) -> Self { | |
256 | BinaryHeap { data: self.data.clone() } | |
257 | } | |
258 | ||
259 | fn clone_from(&mut self, source: &Self) { | |
260 | self.data.clone_from(&source.data); | |
261 | } | |
262 | } | |
263 | ||
85aaf69f | 264 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 265 | impl<T: Ord> Default for BinaryHeap<T> { |
9e0c209e | 266 | /// Creates an empty `BinaryHeap<T>`. |
1a4d82fc | 267 | #[inline] |
92a42be0 SL |
268 | fn default() -> BinaryHeap<T> { |
269 | BinaryHeap::new() | |
270 | } | |
1a4d82fc JJ |
271 | } |
272 | ||
e9174d1e SL |
273 | #[stable(feature = "binaryheap_debug", since = "1.4.0")] |
274 | impl<T: fmt::Debug + Ord> fmt::Debug for BinaryHeap<T> { | |
275 | fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { | |
276 | f.debug_list().entries(self.iter()).finish() | |
277 | } | |
278 | } | |
279 | ||
1a4d82fc JJ |
280 | impl<T: Ord> BinaryHeap<T> { |
281 | /// Creates an empty `BinaryHeap` as a max-heap. | |
282 | /// | |
283 | /// # Examples | |
284 | /// | |
54a0048b SL |
285 | /// Basic usage: |
286 | /// | |
1a4d82fc JJ |
287 | /// ``` |
288 | /// use std::collections::BinaryHeap; | |
289 | /// let mut heap = BinaryHeap::new(); | |
85aaf69f | 290 | /// heap.push(4); |
1a4d82fc | 291 | /// ``` |
85aaf69f | 292 | #[stable(feature = "rust1", since = "1.0.0")] |
92a42be0 SL |
293 | pub fn new() -> BinaryHeap<T> { |
294 | BinaryHeap { data: vec![] } | |
295 | } | |
1a4d82fc JJ |
296 | |
297 | /// Creates an empty `BinaryHeap` with a specific capacity. | |
298 | /// This preallocates enough memory for `capacity` elements, | |
299 | /// so that the `BinaryHeap` does not have to be reallocated | |
300 | /// until it contains at least that many values. | |
301 | /// | |
302 | /// # Examples | |
303 | /// | |
54a0048b SL |
304 | /// Basic usage: |
305 | /// | |
1a4d82fc JJ |
306 | /// ``` |
307 | /// use std::collections::BinaryHeap; | |
308 | /// let mut heap = BinaryHeap::with_capacity(10); | |
85aaf69f | 309 | /// heap.push(4); |
1a4d82fc | 310 | /// ``` |
85aaf69f SL |
311 | #[stable(feature = "rust1", since = "1.0.0")] |
312 | pub fn with_capacity(capacity: usize) -> BinaryHeap<T> { | |
1a4d82fc JJ |
313 | BinaryHeap { data: Vec::with_capacity(capacity) } |
314 | } | |
315 | ||
1a4d82fc JJ |
316 | /// Returns an iterator visiting all values in the underlying vector, in |
317 | /// arbitrary order. | |
318 | /// | |
319 | /// # Examples | |
320 | /// | |
54a0048b SL |
321 | /// Basic usage: |
322 | /// | |
1a4d82fc JJ |
323 | /// ``` |
324 | /// use std::collections::BinaryHeap; | |
b039eaaf | 325 | /// let heap = BinaryHeap::from(vec![1, 2, 3, 4]); |
1a4d82fc JJ |
326 | /// |
327 | /// // Print 1, 2, 3, 4 in arbitrary order | |
328 | /// for x in heap.iter() { | |
329 | /// println!("{}", x); | |
330 | /// } | |
331 | /// ``` | |
85aaf69f | 332 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
333 | pub fn iter(&self) -> Iter<T> { |
334 | Iter { iter: self.data.iter() } | |
335 | } | |
336 | ||
1a4d82fc JJ |
337 | /// Returns the greatest item in the binary heap, or `None` if it is empty. |
338 | /// | |
339 | /// # Examples | |
340 | /// | |
54a0048b SL |
341 | /// Basic usage: |
342 | /// | |
1a4d82fc JJ |
343 | /// ``` |
344 | /// use std::collections::BinaryHeap; | |
345 | /// let mut heap = BinaryHeap::new(); | |
346 | /// assert_eq!(heap.peek(), None); | |
347 | /// | |
85aaf69f | 348 | /// heap.push(1); |
1a4d82fc JJ |
349 | /// heap.push(5); |
350 | /// heap.push(2); | |
351 | /// assert_eq!(heap.peek(), Some(&5)); | |
352 | /// | |
353 | /// ``` | |
85aaf69f | 354 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
355 | pub fn peek(&self) -> Option<&T> { |
356 | self.data.get(0) | |
357 | } | |
358 | ||
3157f602 XL |
359 | /// Returns a mutable reference to the greatest item in the binary heap, or |
360 | /// `None` if it is empty. | |
361 | /// | |
362 | /// Note: If the `PeekMut` value is leaked, the heap may be in an | |
363 | /// inconsistent state. | |
364 | /// | |
365 | /// # Examples | |
366 | /// | |
367 | /// Basic usage: | |
368 | /// | |
369 | /// ``` | |
3157f602 XL |
370 | /// use std::collections::BinaryHeap; |
371 | /// let mut heap = BinaryHeap::new(); | |
372 | /// assert!(heap.peek_mut().is_none()); | |
373 | /// | |
374 | /// heap.push(1); | |
375 | /// heap.push(5); | |
376 | /// heap.push(2); | |
377 | /// { | |
378 | /// let mut val = heap.peek_mut().unwrap(); | |
379 | /// *val = 0; | |
380 | /// } | |
381 | /// assert_eq!(heap.peek(), Some(&2)); | |
382 | /// ``` | |
5bcae85e | 383 | #[stable(feature = "binary_heap_peek_mut", since = "1.12.0")] |
3157f602 XL |
384 | pub fn peek_mut(&mut self) -> Option<PeekMut<T>> { |
385 | if self.is_empty() { | |
386 | None | |
387 | } else { | |
388 | Some(PeekMut { | |
389 | heap: self | |
390 | }) | |
391 | } | |
392 | } | |
393 | ||
1a4d82fc JJ |
394 | /// Returns the number of elements the binary heap can hold without reallocating. |
395 | /// | |
396 | /// # Examples | |
397 | /// | |
54a0048b SL |
398 | /// Basic usage: |
399 | /// | |
1a4d82fc JJ |
400 | /// ``` |
401 | /// use std::collections::BinaryHeap; | |
402 | /// let mut heap = BinaryHeap::with_capacity(100); | |
403 | /// assert!(heap.capacity() >= 100); | |
85aaf69f | 404 | /// heap.push(4); |
1a4d82fc | 405 | /// ``` |
85aaf69f | 406 | #[stable(feature = "rust1", since = "1.0.0")] |
92a42be0 SL |
407 | pub fn capacity(&self) -> usize { |
408 | self.data.capacity() | |
409 | } | |
1a4d82fc JJ |
410 | |
411 | /// Reserves the minimum capacity for exactly `additional` more elements to be inserted in the | |
412 | /// given `BinaryHeap`. Does nothing if the capacity is already sufficient. | |
413 | /// | |
414 | /// Note that the allocator may give the collection more space than it requests. Therefore | |
415 | /// capacity can not be relied upon to be precisely minimal. Prefer `reserve` if future | |
416 | /// insertions are expected. | |
417 | /// | |
418 | /// # Panics | |
419 | /// | |
85aaf69f | 420 | /// Panics if the new capacity overflows `usize`. |
1a4d82fc JJ |
421 | /// |
422 | /// # Examples | |
423 | /// | |
54a0048b SL |
424 | /// Basic usage: |
425 | /// | |
1a4d82fc JJ |
426 | /// ``` |
427 | /// use std::collections::BinaryHeap; | |
428 | /// let mut heap = BinaryHeap::new(); | |
429 | /// heap.reserve_exact(100); | |
430 | /// assert!(heap.capacity() >= 100); | |
85aaf69f | 431 | /// heap.push(4); |
1a4d82fc | 432 | /// ``` |
85aaf69f SL |
433 | #[stable(feature = "rust1", since = "1.0.0")] |
434 | pub fn reserve_exact(&mut self, additional: usize) { | |
1a4d82fc JJ |
435 | self.data.reserve_exact(additional); |
436 | } | |
437 | ||
438 | /// Reserves capacity for at least `additional` more elements to be inserted in the | |
439 | /// `BinaryHeap`. The collection may reserve more space to avoid frequent reallocations. | |
440 | /// | |
441 | /// # Panics | |
442 | /// | |
85aaf69f | 443 | /// Panics if the new capacity overflows `usize`. |
1a4d82fc JJ |
444 | /// |
445 | /// # Examples | |
446 | /// | |
54a0048b SL |
447 | /// Basic usage: |
448 | /// | |
1a4d82fc JJ |
449 | /// ``` |
450 | /// use std::collections::BinaryHeap; | |
451 | /// let mut heap = BinaryHeap::new(); | |
452 | /// heap.reserve(100); | |
453 | /// assert!(heap.capacity() >= 100); | |
85aaf69f | 454 | /// heap.push(4); |
1a4d82fc | 455 | /// ``` |
85aaf69f SL |
456 | #[stable(feature = "rust1", since = "1.0.0")] |
457 | pub fn reserve(&mut self, additional: usize) { | |
1a4d82fc JJ |
458 | self.data.reserve(additional); |
459 | } | |
460 | ||
461 | /// Discards as much additional capacity as possible. | |
54a0048b SL |
462 | /// |
463 | /// # Examples | |
464 | /// | |
465 | /// Basic usage: | |
466 | /// | |
467 | /// ``` | |
468 | /// use std::collections::BinaryHeap; | |
469 | /// let mut heap: BinaryHeap<i32> = BinaryHeap::with_capacity(100); | |
470 | /// | |
471 | /// assert!(heap.capacity() >= 100); | |
472 | /// heap.shrink_to_fit(); | |
473 | /// assert!(heap.capacity() == 0); | |
474 | /// ``` | |
85aaf69f | 475 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
476 | pub fn shrink_to_fit(&mut self) { |
477 | self.data.shrink_to_fit(); | |
478 | } | |
479 | ||
480 | /// Removes the greatest item from the binary heap and returns it, or `None` if it | |
481 | /// is empty. | |
482 | /// | |
483 | /// # Examples | |
484 | /// | |
54a0048b SL |
485 | /// Basic usage: |
486 | /// | |
1a4d82fc JJ |
487 | /// ``` |
488 | /// use std::collections::BinaryHeap; | |
b039eaaf | 489 | /// let mut heap = BinaryHeap::from(vec![1, 3]); |
1a4d82fc JJ |
490 | /// |
491 | /// assert_eq!(heap.pop(), Some(3)); | |
492 | /// assert_eq!(heap.pop(), Some(1)); | |
493 | /// assert_eq!(heap.pop(), None); | |
494 | /// ``` | |
85aaf69f | 495 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
496 | pub fn pop(&mut self) -> Option<T> { |
497 | self.data.pop().map(|mut item| { | |
498 | if !self.is_empty() { | |
499 | swap(&mut item, &mut self.data[0]); | |
9cc50fc6 | 500 | self.sift_down_to_bottom(0); |
1a4d82fc JJ |
501 | } |
502 | item | |
503 | }) | |
504 | } | |
505 | ||
506 | /// Pushes an item onto the binary heap. | |
507 | /// | |
508 | /// # Examples | |
509 | /// | |
54a0048b SL |
510 | /// Basic usage: |
511 | /// | |
1a4d82fc JJ |
512 | /// ``` |
513 | /// use std::collections::BinaryHeap; | |
514 | /// let mut heap = BinaryHeap::new(); | |
85aaf69f | 515 | /// heap.push(3); |
1a4d82fc JJ |
516 | /// heap.push(5); |
517 | /// heap.push(1); | |
518 | /// | |
519 | /// assert_eq!(heap.len(), 3); | |
520 | /// assert_eq!(heap.peek(), Some(&5)); | |
521 | /// ``` | |
85aaf69f | 522 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
523 | pub fn push(&mut self, item: T) { |
524 | let old_len = self.len(); | |
525 | self.data.push(item); | |
526 | self.sift_up(0, old_len); | |
527 | } | |
528 | ||
529 | /// Pushes an item onto the binary heap, then pops the greatest item off the queue in | |
530 | /// an optimized fashion. | |
531 | /// | |
532 | /// # Examples | |
533 | /// | |
54a0048b SL |
534 | /// Basic usage: |
535 | /// | |
1a4d82fc | 536 | /// ``` |
e9174d1e | 537 | /// #![feature(binary_heap_extras)] |
9e0c209e | 538 | /// #![allow(deprecated)] |
c1a9b12d | 539 | /// |
1a4d82fc JJ |
540 | /// use std::collections::BinaryHeap; |
541 | /// let mut heap = BinaryHeap::new(); | |
85aaf69f | 542 | /// heap.push(1); |
1a4d82fc JJ |
543 | /// heap.push(5); |
544 | /// | |
545 | /// assert_eq!(heap.push_pop(3), 5); | |
546 | /// assert_eq!(heap.push_pop(9), 9); | |
547 | /// assert_eq!(heap.len(), 2); | |
548 | /// assert_eq!(heap.peek(), Some(&3)); | |
549 | /// ``` | |
e9174d1e SL |
550 | #[unstable(feature = "binary_heap_extras", |
551 | reason = "needs to be audited", | |
552 | issue = "28147")] | |
9e0c209e | 553 | #[rustc_deprecated(since = "1.13.0", reason = "use `peek_mut` instead")] |
1a4d82fc JJ |
554 | pub fn push_pop(&mut self, mut item: T) -> T { |
555 | match self.data.get_mut(0) { | |
556 | None => return item, | |
92a42be0 SL |
557 | Some(top) => { |
558 | if *top > item { | |
559 | swap(&mut item, top); | |
560 | } else { | |
561 | return item; | |
562 | } | |
563 | } | |
1a4d82fc JJ |
564 | } |
565 | ||
566 | self.sift_down(0); | |
567 | item | |
568 | } | |
569 | ||
570 | /// Pops the greatest item off the binary heap, then pushes an item onto the queue in | |
571 | /// an optimized fashion. The push is done regardless of whether the binary heap | |
572 | /// was empty. | |
573 | /// | |
574 | /// # Examples | |
575 | /// | |
54a0048b SL |
576 | /// Basic usage: |
577 | /// | |
1a4d82fc | 578 | /// ``` |
e9174d1e | 579 | /// #![feature(binary_heap_extras)] |
9e0c209e | 580 | /// #![allow(deprecated)] |
c1a9b12d | 581 | /// |
1a4d82fc JJ |
582 | /// use std::collections::BinaryHeap; |
583 | /// let mut heap = BinaryHeap::new(); | |
584 | /// | |
85aaf69f | 585 | /// assert_eq!(heap.replace(1), None); |
1a4d82fc JJ |
586 | /// assert_eq!(heap.replace(3), Some(1)); |
587 | /// assert_eq!(heap.len(), 1); | |
588 | /// assert_eq!(heap.peek(), Some(&3)); | |
589 | /// ``` | |
e9174d1e SL |
590 | #[unstable(feature = "binary_heap_extras", |
591 | reason = "needs to be audited", | |
592 | issue = "28147")] | |
9e0c209e | 593 | #[rustc_deprecated(since = "1.13.0", reason = "use `peek_mut` instead")] |
1a4d82fc JJ |
594 | pub fn replace(&mut self, mut item: T) -> Option<T> { |
595 | if !self.is_empty() { | |
596 | swap(&mut item, &mut self.data[0]); | |
597 | self.sift_down(0); | |
598 | Some(item) | |
599 | } else { | |
600 | self.push(item); | |
601 | None | |
602 | } | |
603 | } | |
604 | ||
605 | /// Consumes the `BinaryHeap` and returns the underlying vector | |
606 | /// in arbitrary order. | |
607 | /// | |
608 | /// # Examples | |
609 | /// | |
54a0048b SL |
610 | /// Basic usage: |
611 | /// | |
1a4d82fc JJ |
612 | /// ``` |
613 | /// use std::collections::BinaryHeap; | |
b039eaaf | 614 | /// let heap = BinaryHeap::from(vec![1, 2, 3, 4, 5, 6, 7]); |
1a4d82fc JJ |
615 | /// let vec = heap.into_vec(); |
616 | /// | |
617 | /// // Will print in some order | |
62682a34 | 618 | /// for x in vec { |
1a4d82fc JJ |
619 | /// println!("{}", x); |
620 | /// } | |
621 | /// ``` | |
b039eaaf SL |
622 | #[stable(feature = "binary_heap_extras_15", since = "1.5.0")] |
623 | pub fn into_vec(self) -> Vec<T> { | |
624 | self.into() | |
625 | } | |
1a4d82fc JJ |
626 | |
627 | /// Consumes the `BinaryHeap` and returns a vector in sorted | |
628 | /// (ascending) order. | |
629 | /// | |
630 | /// # Examples | |
631 | /// | |
54a0048b SL |
632 | /// Basic usage: |
633 | /// | |
1a4d82fc JJ |
634 | /// ``` |
635 | /// use std::collections::BinaryHeap; | |
636 | /// | |
b039eaaf | 637 | /// let mut heap = BinaryHeap::from(vec![1, 2, 4, 5, 7]); |
1a4d82fc JJ |
638 | /// heap.push(6); |
639 | /// heap.push(3); | |
640 | /// | |
641 | /// let vec = heap.into_sorted_vec(); | |
c34b1796 | 642 | /// assert_eq!(vec, [1, 2, 3, 4, 5, 6, 7]); |
1a4d82fc | 643 | /// ``` |
b039eaaf | 644 | #[stable(feature = "binary_heap_extras_15", since = "1.5.0")] |
1a4d82fc JJ |
645 | pub fn into_sorted_vec(mut self) -> Vec<T> { |
646 | let mut end = self.len(); | |
647 | while end > 1 { | |
648 | end -= 1; | |
649 | self.data.swap(0, end); | |
650 | self.sift_down_range(0, end); | |
651 | } | |
652 | self.into_vec() | |
653 | } | |
654 | ||
655 | // The implementations of sift_up and sift_down use unsafe blocks in | |
656 | // order to move an element out of the vector (leaving behind a | |
d9579d0f AL |
657 | // hole), shift along the others and move the removed element back into the |
658 | // vector at the final location of the hole. | |
659 | // The `Hole` type is used to represent this, and make sure | |
660 | // the hole is filled back at the end of its scope, even on panic. | |
661 | // Using a hole reduces the constant factor compared to using swaps, | |
662 | // which involves twice as many moves. | |
663 | fn sift_up(&mut self, start: usize, pos: usize) { | |
1a4d82fc | 664 | unsafe { |
d9579d0f AL |
665 | // Take out the value at `pos` and create a hole. |
666 | let mut hole = Hole::new(&mut self.data, pos); | |
1a4d82fc | 667 | |
d9579d0f AL |
668 | while hole.pos() > start { |
669 | let parent = (hole.pos() - 1) / 2; | |
92a42be0 SL |
670 | if hole.element() <= hole.get(parent) { |
671 | break; | |
672 | } | |
d9579d0f | 673 | hole.move_to(parent); |
1a4d82fc | 674 | } |
1a4d82fc JJ |
675 | } |
676 | } | |
677 | ||
92a42be0 SL |
678 | /// Take an element at `pos` and move it down the heap, |
679 | /// while its children are larger. | |
680 | fn sift_down_range(&mut self, pos: usize, end: usize) { | |
1a4d82fc | 681 | unsafe { |
d9579d0f | 682 | let mut hole = Hole::new(&mut self.data, pos); |
1a4d82fc JJ |
683 | let mut child = 2 * pos + 1; |
684 | while child < end { | |
685 | let right = child + 1; | |
92a42be0 | 686 | // compare with the greater of the two children |
d9579d0f | 687 | if right < end && !(hole.get(child) > hole.get(right)) { |
1a4d82fc JJ |
688 | child = right; |
689 | } | |
92a42be0 SL |
690 | // if we are already in order, stop. |
691 | if hole.element() >= hole.get(child) { | |
692 | break; | |
693 | } | |
d9579d0f AL |
694 | hole.move_to(child); |
695 | child = 2 * hole.pos() + 1; | |
1a4d82fc | 696 | } |
1a4d82fc JJ |
697 | } |
698 | } | |
699 | ||
85aaf69f | 700 | fn sift_down(&mut self, pos: usize) { |
1a4d82fc JJ |
701 | let len = self.len(); |
702 | self.sift_down_range(pos, len); | |
703 | } | |
704 | ||
9cc50fc6 SL |
705 | /// Take an element at `pos` and move it all the way down the heap, |
706 | /// then sift it up to its position. | |
707 | /// | |
708 | /// Note: This is faster when the element is known to be large / should | |
709 | /// be closer to the bottom. | |
710 | fn sift_down_to_bottom(&mut self, mut pos: usize) { | |
711 | let end = self.len(); | |
712 | let start = pos; | |
713 | unsafe { | |
714 | let mut hole = Hole::new(&mut self.data, pos); | |
715 | let mut child = 2 * pos + 1; | |
716 | while child < end { | |
717 | let right = child + 1; | |
718 | // compare with the greater of the two children | |
719 | if right < end && !(hole.get(child) > hole.get(right)) { | |
720 | child = right; | |
721 | } | |
722 | hole.move_to(child); | |
723 | child = 2 * hole.pos() + 1; | |
724 | } | |
725 | pos = hole.pos; | |
726 | } | |
727 | self.sift_up(start, pos); | |
728 | } | |
729 | ||
1a4d82fc | 730 | /// Returns the length of the binary heap. |
54a0048b SL |
731 | /// |
732 | /// # Examples | |
733 | /// | |
734 | /// Basic usage: | |
735 | /// | |
736 | /// ``` | |
737 | /// use std::collections::BinaryHeap; | |
738 | /// let heap = BinaryHeap::from(vec![1, 3]); | |
739 | /// | |
740 | /// assert_eq!(heap.len(), 2); | |
741 | /// ``` | |
85aaf69f | 742 | #[stable(feature = "rust1", since = "1.0.0")] |
92a42be0 SL |
743 | pub fn len(&self) -> usize { |
744 | self.data.len() | |
745 | } | |
1a4d82fc JJ |
746 | |
747 | /// Checks if the binary heap is empty. | |
54a0048b SL |
748 | /// |
749 | /// # Examples | |
750 | /// | |
751 | /// Basic usage: | |
752 | /// | |
753 | /// ``` | |
754 | /// use std::collections::BinaryHeap; | |
755 | /// let mut heap = BinaryHeap::new(); | |
756 | /// | |
757 | /// assert!(heap.is_empty()); | |
758 | /// | |
759 | /// heap.push(3); | |
760 | /// heap.push(5); | |
761 | /// heap.push(1); | |
762 | /// | |
763 | /// assert!(!heap.is_empty()); | |
764 | /// ``` | |
85aaf69f | 765 | #[stable(feature = "rust1", since = "1.0.0")] |
92a42be0 SL |
766 | pub fn is_empty(&self) -> bool { |
767 | self.len() == 0 | |
768 | } | |
1a4d82fc JJ |
769 | |
770 | /// Clears the binary heap, returning an iterator over the removed elements. | |
c34b1796 AL |
771 | /// |
772 | /// The elements are removed in arbitrary order. | |
54a0048b SL |
773 | /// |
774 | /// # Examples | |
775 | /// | |
776 | /// Basic usage: | |
777 | /// | |
778 | /// ``` | |
779 | /// use std::collections::BinaryHeap; | |
780 | /// let mut heap = BinaryHeap::from(vec![1, 3]); | |
781 | /// | |
782 | /// assert!(!heap.is_empty()); | |
783 | /// | |
784 | /// for x in heap.drain() { | |
785 | /// println!("{}", x); | |
786 | /// } | |
787 | /// | |
788 | /// assert!(heap.is_empty()); | |
789 | /// ``` | |
1a4d82fc | 790 | #[inline] |
92a42be0 | 791 | #[stable(feature = "drain", since = "1.6.0")] |
1a4d82fc | 792 | pub fn drain(&mut self) -> Drain<T> { |
d9579d0f | 793 | Drain { iter: self.data.drain(..) } |
1a4d82fc JJ |
794 | } |
795 | ||
796 | /// Drops all items from the binary heap. | |
54a0048b SL |
797 | /// |
798 | /// # Examples | |
799 | /// | |
800 | /// Basic usage: | |
801 | /// | |
802 | /// ``` | |
803 | /// use std::collections::BinaryHeap; | |
804 | /// let mut heap = BinaryHeap::from(vec![1, 3]); | |
805 | /// | |
806 | /// assert!(!heap.is_empty()); | |
807 | /// | |
808 | /// heap.clear(); | |
809 | /// | |
810 | /// assert!(heap.is_empty()); | |
811 | /// ``` | |
85aaf69f | 812 | #[stable(feature = "rust1", since = "1.0.0")] |
92a42be0 SL |
813 | pub fn clear(&mut self) { |
814 | self.drain(); | |
815 | } | |
a7813a04 XL |
816 | |
817 | fn rebuild(&mut self) { | |
818 | let mut n = self.len() / 2; | |
819 | while n > 0 { | |
820 | n -= 1; | |
821 | self.sift_down(n); | |
822 | } | |
823 | } | |
824 | ||
825 | /// Moves all the elements of `other` into `self`, leaving `other` empty. | |
826 | /// | |
827 | /// # Examples | |
828 | /// | |
829 | /// Basic usage: | |
830 | /// | |
831 | /// ``` | |
a7813a04 XL |
832 | /// use std::collections::BinaryHeap; |
833 | /// | |
834 | /// let v = vec![-10, 1, 2, 3, 3]; | |
835 | /// let mut a = BinaryHeap::from(v); | |
836 | /// | |
837 | /// let v = vec![-20, 5, 43]; | |
838 | /// let mut b = BinaryHeap::from(v); | |
839 | /// | |
840 | /// a.append(&mut b); | |
841 | /// | |
842 | /// assert_eq!(a.into_sorted_vec(), [-20, -10, 1, 2, 3, 3, 5, 43]); | |
843 | /// assert!(b.is_empty()); | |
844 | /// ``` | |
3157f602 | 845 | #[stable(feature = "binary_heap_append", since = "1.11.0")] |
a7813a04 XL |
846 | pub fn append(&mut self, other: &mut Self) { |
847 | if self.len() < other.len() { | |
848 | swap(self, other); | |
849 | } | |
850 | ||
851 | if other.is_empty() { | |
852 | return; | |
853 | } | |
854 | ||
855 | #[inline(always)] | |
856 | fn log2_fast(x: usize) -> usize { | |
857 | 8 * size_of::<usize>() - (x.leading_zeros() as usize) - 1 | |
858 | } | |
859 | ||
860 | // `rebuild` takes O(len1 + len2) operations | |
861 | // and about 2 * (len1 + len2) comparisons in the worst case | |
862 | // while `extend` takes O(len2 * log_2(len1)) operations | |
863 | // and about 1 * len2 * log_2(len1) comparisons in the worst case, | |
864 | // assuming len1 >= len2. | |
865 | #[inline] | |
866 | fn better_to_rebuild(len1: usize, len2: usize) -> bool { | |
867 | 2 * (len1 + len2) < len2 * log2_fast(len1) | |
868 | } | |
869 | ||
870 | if better_to_rebuild(self.len(), other.len()) { | |
871 | self.data.append(&mut other.data); | |
872 | self.rebuild(); | |
873 | } else { | |
874 | self.extend(other.drain()); | |
875 | } | |
876 | } | |
1a4d82fc JJ |
877 | } |
878 | ||
d9579d0f AL |
879 | /// Hole represents a hole in a slice i.e. an index without valid value |
880 | /// (because it was moved from or duplicated). | |
881 | /// In drop, `Hole` will restore the slice by filling the hole | |
882 | /// position with the value that was originally removed. | |
883 | struct Hole<'a, T: 'a> { | |
884 | data: &'a mut [T], | |
885 | /// `elt` is always `Some` from new until drop. | |
886 | elt: Option<T>, | |
887 | pos: usize, | |
888 | } | |
889 | ||
890 | impl<'a, T> Hole<'a, T> { | |
891 | /// Create a new Hole at index `pos`. | |
9e0c209e SL |
892 | /// |
893 | /// Unsafe because pos must be within the data slice. | |
894 | #[inline] | |
895 | unsafe fn new(data: &'a mut [T], pos: usize) -> Self { | |
896 | debug_assert!(pos < data.len()); | |
897 | let elt = ptr::read(&data[pos]); | |
898 | Hole { | |
899 | data: data, | |
900 | elt: Some(elt), | |
901 | pos: pos, | |
d9579d0f AL |
902 | } |
903 | } | |
904 | ||
9e0c209e | 905 | #[inline] |
92a42be0 SL |
906 | fn pos(&self) -> usize { |
907 | self.pos | |
908 | } | |
d9579d0f AL |
909 | |
910 | /// Return a reference to the element removed | |
9e0c209e | 911 | #[inline] |
92a42be0 | 912 | fn element(&self) -> &T { |
d9579d0f AL |
913 | self.elt.as_ref().unwrap() |
914 | } | |
915 | ||
916 | /// Return a reference to the element at `index`. | |
917 | /// | |
9e0c209e SL |
918 | /// Unsafe because index must be within the data slice and not equal to pos. |
919 | #[inline] | |
d9579d0f AL |
920 | unsafe fn get(&self, index: usize) -> &T { |
921 | debug_assert!(index != self.pos); | |
9e0c209e SL |
922 | debug_assert!(index < self.data.len()); |
923 | self.data.get_unchecked(index) | |
d9579d0f AL |
924 | } |
925 | ||
926 | /// Move hole to new location | |
927 | /// | |
9e0c209e SL |
928 | /// Unsafe because index must be within the data slice and not equal to pos. |
929 | #[inline] | |
d9579d0f AL |
930 | unsafe fn move_to(&mut self, index: usize) { |
931 | debug_assert!(index != self.pos); | |
9e0c209e SL |
932 | debug_assert!(index < self.data.len()); |
933 | let index_ptr: *const _ = self.data.get_unchecked(index); | |
934 | let hole_ptr = self.data.get_unchecked_mut(self.pos); | |
d9579d0f AL |
935 | ptr::copy_nonoverlapping(index_ptr, hole_ptr, 1); |
936 | self.pos = index; | |
937 | } | |
938 | } | |
939 | ||
940 | impl<'a, T> Drop for Hole<'a, T> { | |
9e0c209e | 941 | #[inline] |
d9579d0f AL |
942 | fn drop(&mut self) { |
943 | // fill the hole again | |
944 | unsafe { | |
945 | let pos = self.pos; | |
9e0c209e | 946 | ptr::write(self.data.get_unchecked_mut(pos), self.elt.take().unwrap()); |
d9579d0f AL |
947 | } |
948 | } | |
949 | } | |
950 | ||
1a4d82fc | 951 | /// `BinaryHeap` iterator. |
85aaf69f | 952 | #[stable(feature = "rust1", since = "1.0.0")] |
92a42be0 | 953 | pub struct Iter<'a, T: 'a> { |
1a4d82fc JJ |
954 | iter: slice::Iter<'a, T>, |
955 | } | |
956 | ||
957 | // FIXME(#19839) Remove in favor of `#[derive(Clone)]` | |
85aaf69f | 958 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
959 | impl<'a, T> Clone for Iter<'a, T> { |
960 | fn clone(&self) -> Iter<'a, T> { | |
961 | Iter { iter: self.iter.clone() } | |
962 | } | |
963 | } | |
964 | ||
85aaf69f | 965 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
966 | impl<'a, T> Iterator for Iter<'a, T> { |
967 | type Item = &'a T; | |
968 | ||
969 | #[inline] | |
92a42be0 SL |
970 | fn next(&mut self) -> Option<&'a T> { |
971 | self.iter.next() | |
972 | } | |
1a4d82fc JJ |
973 | |
974 | #[inline] | |
92a42be0 SL |
975 | fn size_hint(&self) -> (usize, Option<usize>) { |
976 | self.iter.size_hint() | |
977 | } | |
1a4d82fc JJ |
978 | } |
979 | ||
85aaf69f | 980 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
981 | impl<'a, T> DoubleEndedIterator for Iter<'a, T> { |
982 | #[inline] | |
92a42be0 SL |
983 | fn next_back(&mut self) -> Option<&'a T> { |
984 | self.iter.next_back() | |
985 | } | |
1a4d82fc JJ |
986 | } |
987 | ||
85aaf69f | 988 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
989 | impl<'a, T> ExactSizeIterator for Iter<'a, T> {} |
990 | ||
9e0c209e SL |
991 | #[unstable(feature = "fused", issue = "35602")] |
992 | impl<'a, T> FusedIterator for Iter<'a, T> {} | |
993 | ||
1a4d82fc | 994 | /// An iterator that moves out of a `BinaryHeap`. |
85aaf69f | 995 | #[stable(feature = "rust1", since = "1.0.0")] |
a7813a04 | 996 | #[derive(Clone)] |
1a4d82fc JJ |
997 | pub struct IntoIter<T> { |
998 | iter: vec::IntoIter<T>, | |
999 | } | |
1000 | ||
85aaf69f | 1001 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
1002 | impl<T> Iterator for IntoIter<T> { |
1003 | type Item = T; | |
1004 | ||
1005 | #[inline] | |
92a42be0 SL |
1006 | fn next(&mut self) -> Option<T> { |
1007 | self.iter.next() | |
1008 | } | |
1a4d82fc JJ |
1009 | |
1010 | #[inline] | |
92a42be0 SL |
1011 | fn size_hint(&self) -> (usize, Option<usize>) { |
1012 | self.iter.size_hint() | |
1013 | } | |
1a4d82fc JJ |
1014 | } |
1015 | ||
85aaf69f | 1016 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
1017 | impl<T> DoubleEndedIterator for IntoIter<T> { |
1018 | #[inline] | |
92a42be0 SL |
1019 | fn next_back(&mut self) -> Option<T> { |
1020 | self.iter.next_back() | |
1021 | } | |
1a4d82fc JJ |
1022 | } |
1023 | ||
85aaf69f | 1024 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
1025 | impl<T> ExactSizeIterator for IntoIter<T> {} |
1026 | ||
9e0c209e SL |
1027 | #[unstable(feature = "fused", issue = "35602")] |
1028 | impl<T> FusedIterator for IntoIter<T> {} | |
1029 | ||
1a4d82fc | 1030 | /// An iterator that drains a `BinaryHeap`. |
92a42be0 | 1031 | #[stable(feature = "drain", since = "1.6.0")] |
1a4d82fc JJ |
1032 | pub struct Drain<'a, T: 'a> { |
1033 | iter: vec::Drain<'a, T>, | |
1034 | } | |
1035 | ||
c30ab7b3 | 1036 | #[stable(feature = "drain", since = "1.6.0")] |
1a4d82fc JJ |
1037 | impl<'a, T: 'a> Iterator for Drain<'a, T> { |
1038 | type Item = T; | |
1039 | ||
1040 | #[inline] | |
92a42be0 SL |
1041 | fn next(&mut self) -> Option<T> { |
1042 | self.iter.next() | |
1043 | } | |
1a4d82fc JJ |
1044 | |
1045 | #[inline] | |
92a42be0 SL |
1046 | fn size_hint(&self) -> (usize, Option<usize>) { |
1047 | self.iter.size_hint() | |
1048 | } | |
1a4d82fc JJ |
1049 | } |
1050 | ||
c30ab7b3 | 1051 | #[stable(feature = "drain", since = "1.6.0")] |
1a4d82fc JJ |
1052 | impl<'a, T: 'a> DoubleEndedIterator for Drain<'a, T> { |
1053 | #[inline] | |
92a42be0 SL |
1054 | fn next_back(&mut self) -> Option<T> { |
1055 | self.iter.next_back() | |
1056 | } | |
1a4d82fc JJ |
1057 | } |
1058 | ||
c30ab7b3 | 1059 | #[stable(feature = "drain", since = "1.6.0")] |
1a4d82fc JJ |
1060 | impl<'a, T: 'a> ExactSizeIterator for Drain<'a, T> {} |
1061 | ||
9e0c209e SL |
1062 | #[unstable(feature = "fused", issue = "35602")] |
1063 | impl<'a, T: 'a> FusedIterator for Drain<'a, T> {} | |
1064 | ||
92a42be0 | 1065 | #[stable(feature = "rust1", since = "1.0.0")] |
b039eaaf SL |
1066 | impl<T: Ord> From<Vec<T>> for BinaryHeap<T> { |
1067 | fn from(vec: Vec<T>) -> BinaryHeap<T> { | |
1068 | let mut heap = BinaryHeap { data: vec }; | |
a7813a04 | 1069 | heap.rebuild(); |
b039eaaf SL |
1070 | heap |
1071 | } | |
1072 | } | |
1073 | ||
92a42be0 | 1074 | #[stable(feature = "rust1", since = "1.0.0")] |
b039eaaf SL |
1075 | impl<T> From<BinaryHeap<T>> for Vec<T> { |
1076 | fn from(heap: BinaryHeap<T>) -> Vec<T> { | |
1077 | heap.data | |
1078 | } | |
1079 | } | |
1080 | ||
85aaf69f | 1081 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 1082 | impl<T: Ord> FromIterator<T> for BinaryHeap<T> { |
92a42be0 | 1083 | fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> BinaryHeap<T> { |
b039eaaf | 1084 | BinaryHeap::from(iter.into_iter().collect::<Vec<_>>()) |
85aaf69f SL |
1085 | } |
1086 | } | |
1087 | ||
1088 | #[stable(feature = "rust1", since = "1.0.0")] | |
1089 | impl<T: Ord> IntoIterator for BinaryHeap<T> { | |
1090 | type Item = T; | |
1091 | type IntoIter = IntoIter<T>; | |
1092 | ||
9346a6ac AL |
1093 | /// Creates a consuming iterator, that is, one that moves each value out of |
1094 | /// the binary heap in arbitrary order. The binary heap cannot be used | |
1095 | /// after calling this. | |
1096 | /// | |
1097 | /// # Examples | |
1098 | /// | |
54a0048b SL |
1099 | /// Basic usage: |
1100 | /// | |
9346a6ac | 1101 | /// ``` |
9346a6ac | 1102 | /// use std::collections::BinaryHeap; |
b039eaaf | 1103 | /// let heap = BinaryHeap::from(vec![1, 2, 3, 4]); |
9346a6ac AL |
1104 | /// |
1105 | /// // Print 1, 2, 3, 4 in arbitrary order | |
1106 | /// for x in heap.into_iter() { | |
1107 | /// // x has type i32, not &i32 | |
1108 | /// println!("{}", x); | |
1109 | /// } | |
1110 | /// ``` | |
85aaf69f | 1111 | fn into_iter(self) -> IntoIter<T> { |
9346a6ac | 1112 | IntoIter { iter: self.data.into_iter() } |
85aaf69f SL |
1113 | } |
1114 | } | |
1115 | ||
1116 | #[stable(feature = "rust1", since = "1.0.0")] | |
1117 | impl<'a, T> IntoIterator for &'a BinaryHeap<T> where T: Ord { | |
1118 | type Item = &'a T; | |
1119 | type IntoIter = Iter<'a, T>; | |
1120 | ||
1121 | fn into_iter(self) -> Iter<'a, T> { | |
1122 | self.iter() | |
1a4d82fc JJ |
1123 | } |
1124 | } | |
1125 | ||
85aaf69f | 1126 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 1127 | impl<T: Ord> Extend<T> for BinaryHeap<T> { |
a7813a04 | 1128 | #[inline] |
54a0048b | 1129 | fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I) { |
a7813a04 XL |
1130 | <Self as SpecExtend<I>>::spec_extend(self, iter); |
1131 | } | |
1132 | } | |
1133 | ||
1134 | impl<T: Ord, I: IntoIterator<Item = T>> SpecExtend<I> for BinaryHeap<T> { | |
1135 | default fn spec_extend(&mut self, iter: I) { | |
1136 | self.extend_desugared(iter.into_iter()); | |
1137 | } | |
1138 | } | |
1139 | ||
1140 | impl<T: Ord> SpecExtend<BinaryHeap<T>> for BinaryHeap<T> { | |
1141 | fn spec_extend(&mut self, ref mut other: BinaryHeap<T>) { | |
1142 | self.append(other); | |
1143 | } | |
1144 | } | |
1145 | ||
1146 | impl<T: Ord> BinaryHeap<T> { | |
1147 | fn extend_desugared<I: IntoIterator<Item = T>>(&mut self, iter: I) { | |
54a0048b SL |
1148 | let iterator = iter.into_iter(); |
1149 | let (lower, _) = iterator.size_hint(); | |
1a4d82fc JJ |
1150 | |
1151 | self.reserve(lower); | |
1152 | ||
54a0048b | 1153 | for elem in iterator { |
1a4d82fc JJ |
1154 | self.push(elem); |
1155 | } | |
1156 | } | |
1157 | } | |
62682a34 SL |
1158 | |
1159 | #[stable(feature = "extend_ref", since = "1.2.0")] | |
1160 | impl<'a, T: 'a + Ord + Copy> Extend<&'a T> for BinaryHeap<T> { | |
92a42be0 | 1161 | fn extend<I: IntoIterator<Item = &'a T>>(&mut self, iter: I) { |
62682a34 SL |
1162 | self.extend(iter.into_iter().cloned()); |
1163 | } | |
1164 | } |