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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 | |
3157f602 | 154 | use core::ops::{Drop, Deref, DerefMut}; |
92a42be0 | 155 | use core::iter::FromIterator; |
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 JJ |
265 | impl<T: Ord> Default for BinaryHeap<T> { |
266 | #[inline] | |
92a42be0 SL |
267 | fn default() -> BinaryHeap<T> { |
268 | BinaryHeap::new() | |
269 | } | |
1a4d82fc JJ |
270 | } |
271 | ||
e9174d1e SL |
272 | #[stable(feature = "binaryheap_debug", since = "1.4.0")] |
273 | impl<T: fmt::Debug + Ord> fmt::Debug for BinaryHeap<T> { | |
274 | fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { | |
275 | f.debug_list().entries(self.iter()).finish() | |
276 | } | |
277 | } | |
278 | ||
1a4d82fc JJ |
279 | impl<T: Ord> BinaryHeap<T> { |
280 | /// Creates an empty `BinaryHeap` as a max-heap. | |
281 | /// | |
282 | /// # Examples | |
283 | /// | |
54a0048b SL |
284 | /// Basic usage: |
285 | /// | |
1a4d82fc JJ |
286 | /// ``` |
287 | /// use std::collections::BinaryHeap; | |
288 | /// let mut heap = BinaryHeap::new(); | |
85aaf69f | 289 | /// heap.push(4); |
1a4d82fc | 290 | /// ``` |
85aaf69f | 291 | #[stable(feature = "rust1", since = "1.0.0")] |
92a42be0 SL |
292 | pub fn new() -> BinaryHeap<T> { |
293 | BinaryHeap { data: vec![] } | |
294 | } | |
1a4d82fc JJ |
295 | |
296 | /// Creates an empty `BinaryHeap` with a specific capacity. | |
297 | /// This preallocates enough memory for `capacity` elements, | |
298 | /// so that the `BinaryHeap` does not have to be reallocated | |
299 | /// until it contains at least that many values. | |
300 | /// | |
301 | /// # Examples | |
302 | /// | |
54a0048b SL |
303 | /// Basic usage: |
304 | /// | |
1a4d82fc JJ |
305 | /// ``` |
306 | /// use std::collections::BinaryHeap; | |
307 | /// let mut heap = BinaryHeap::with_capacity(10); | |
85aaf69f | 308 | /// heap.push(4); |
1a4d82fc | 309 | /// ``` |
85aaf69f SL |
310 | #[stable(feature = "rust1", since = "1.0.0")] |
311 | pub fn with_capacity(capacity: usize) -> BinaryHeap<T> { | |
1a4d82fc JJ |
312 | BinaryHeap { data: Vec::with_capacity(capacity) } |
313 | } | |
314 | ||
1a4d82fc JJ |
315 | /// Returns an iterator visiting all values in the underlying vector, in |
316 | /// arbitrary order. | |
317 | /// | |
318 | /// # Examples | |
319 | /// | |
54a0048b SL |
320 | /// Basic usage: |
321 | /// | |
1a4d82fc JJ |
322 | /// ``` |
323 | /// use std::collections::BinaryHeap; | |
b039eaaf | 324 | /// let heap = BinaryHeap::from(vec![1, 2, 3, 4]); |
1a4d82fc JJ |
325 | /// |
326 | /// // Print 1, 2, 3, 4 in arbitrary order | |
327 | /// for x in heap.iter() { | |
328 | /// println!("{}", x); | |
329 | /// } | |
330 | /// ``` | |
85aaf69f | 331 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
332 | pub fn iter(&self) -> Iter<T> { |
333 | Iter { iter: self.data.iter() } | |
334 | } | |
335 | ||
1a4d82fc JJ |
336 | /// Returns the greatest item in the binary heap, or `None` if it is empty. |
337 | /// | |
338 | /// # Examples | |
339 | /// | |
54a0048b SL |
340 | /// Basic usage: |
341 | /// | |
1a4d82fc JJ |
342 | /// ``` |
343 | /// use std::collections::BinaryHeap; | |
344 | /// let mut heap = BinaryHeap::new(); | |
345 | /// assert_eq!(heap.peek(), None); | |
346 | /// | |
85aaf69f | 347 | /// heap.push(1); |
1a4d82fc JJ |
348 | /// heap.push(5); |
349 | /// heap.push(2); | |
350 | /// assert_eq!(heap.peek(), Some(&5)); | |
351 | /// | |
352 | /// ``` | |
85aaf69f | 353 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
354 | pub fn peek(&self) -> Option<&T> { |
355 | self.data.get(0) | |
356 | } | |
357 | ||
3157f602 XL |
358 | /// Returns a mutable reference to the greatest item in the binary heap, or |
359 | /// `None` if it is empty. | |
360 | /// | |
361 | /// Note: If the `PeekMut` value is leaked, the heap may be in an | |
362 | /// inconsistent state. | |
363 | /// | |
364 | /// # Examples | |
365 | /// | |
366 | /// Basic usage: | |
367 | /// | |
368 | /// ``` | |
3157f602 XL |
369 | /// use std::collections::BinaryHeap; |
370 | /// let mut heap = BinaryHeap::new(); | |
371 | /// assert!(heap.peek_mut().is_none()); | |
372 | /// | |
373 | /// heap.push(1); | |
374 | /// heap.push(5); | |
375 | /// heap.push(2); | |
376 | /// { | |
377 | /// let mut val = heap.peek_mut().unwrap(); | |
378 | /// *val = 0; | |
379 | /// } | |
380 | /// assert_eq!(heap.peek(), Some(&2)); | |
381 | /// ``` | |
5bcae85e | 382 | #[stable(feature = "binary_heap_peek_mut", since = "1.12.0")] |
3157f602 XL |
383 | pub fn peek_mut(&mut self) -> Option<PeekMut<T>> { |
384 | if self.is_empty() { | |
385 | None | |
386 | } else { | |
387 | Some(PeekMut { | |
388 | heap: self | |
389 | }) | |
390 | } | |
391 | } | |
392 | ||
1a4d82fc JJ |
393 | /// Returns the number of elements the binary heap can hold without reallocating. |
394 | /// | |
395 | /// # Examples | |
396 | /// | |
54a0048b SL |
397 | /// Basic usage: |
398 | /// | |
1a4d82fc JJ |
399 | /// ``` |
400 | /// use std::collections::BinaryHeap; | |
401 | /// let mut heap = BinaryHeap::with_capacity(100); | |
402 | /// assert!(heap.capacity() >= 100); | |
85aaf69f | 403 | /// heap.push(4); |
1a4d82fc | 404 | /// ``` |
85aaf69f | 405 | #[stable(feature = "rust1", since = "1.0.0")] |
92a42be0 SL |
406 | pub fn capacity(&self) -> usize { |
407 | self.data.capacity() | |
408 | } | |
1a4d82fc JJ |
409 | |
410 | /// Reserves the minimum capacity for exactly `additional` more elements to be inserted in the | |
411 | /// given `BinaryHeap`. Does nothing if the capacity is already sufficient. | |
412 | /// | |
413 | /// Note that the allocator may give the collection more space than it requests. Therefore | |
414 | /// capacity can not be relied upon to be precisely minimal. Prefer `reserve` if future | |
415 | /// insertions are expected. | |
416 | /// | |
417 | /// # Panics | |
418 | /// | |
85aaf69f | 419 | /// Panics if the new capacity overflows `usize`. |
1a4d82fc JJ |
420 | /// |
421 | /// # Examples | |
422 | /// | |
54a0048b SL |
423 | /// Basic usage: |
424 | /// | |
1a4d82fc JJ |
425 | /// ``` |
426 | /// use std::collections::BinaryHeap; | |
427 | /// let mut heap = BinaryHeap::new(); | |
428 | /// heap.reserve_exact(100); | |
429 | /// assert!(heap.capacity() >= 100); | |
85aaf69f | 430 | /// heap.push(4); |
1a4d82fc | 431 | /// ``` |
85aaf69f SL |
432 | #[stable(feature = "rust1", since = "1.0.0")] |
433 | pub fn reserve_exact(&mut self, additional: usize) { | |
1a4d82fc JJ |
434 | self.data.reserve_exact(additional); |
435 | } | |
436 | ||
437 | /// Reserves capacity for at least `additional` more elements to be inserted in the | |
438 | /// `BinaryHeap`. The collection may reserve more space to avoid frequent reallocations. | |
439 | /// | |
440 | /// # Panics | |
441 | /// | |
85aaf69f | 442 | /// Panics if the new capacity overflows `usize`. |
1a4d82fc JJ |
443 | /// |
444 | /// # Examples | |
445 | /// | |
54a0048b SL |
446 | /// Basic usage: |
447 | /// | |
1a4d82fc JJ |
448 | /// ``` |
449 | /// use std::collections::BinaryHeap; | |
450 | /// let mut heap = BinaryHeap::new(); | |
451 | /// heap.reserve(100); | |
452 | /// assert!(heap.capacity() >= 100); | |
85aaf69f | 453 | /// heap.push(4); |
1a4d82fc | 454 | /// ``` |
85aaf69f SL |
455 | #[stable(feature = "rust1", since = "1.0.0")] |
456 | pub fn reserve(&mut self, additional: usize) { | |
1a4d82fc JJ |
457 | self.data.reserve(additional); |
458 | } | |
459 | ||
460 | /// Discards as much additional capacity as possible. | |
54a0048b SL |
461 | /// |
462 | /// # Examples | |
463 | /// | |
464 | /// Basic usage: | |
465 | /// | |
466 | /// ``` | |
467 | /// use std::collections::BinaryHeap; | |
468 | /// let mut heap: BinaryHeap<i32> = BinaryHeap::with_capacity(100); | |
469 | /// | |
470 | /// assert!(heap.capacity() >= 100); | |
471 | /// heap.shrink_to_fit(); | |
472 | /// assert!(heap.capacity() == 0); | |
473 | /// ``` | |
85aaf69f | 474 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
475 | pub fn shrink_to_fit(&mut self) { |
476 | self.data.shrink_to_fit(); | |
477 | } | |
478 | ||
479 | /// Removes the greatest item from the binary heap and returns it, or `None` if it | |
480 | /// is empty. | |
481 | /// | |
482 | /// # Examples | |
483 | /// | |
54a0048b SL |
484 | /// Basic usage: |
485 | /// | |
1a4d82fc JJ |
486 | /// ``` |
487 | /// use std::collections::BinaryHeap; | |
b039eaaf | 488 | /// let mut heap = BinaryHeap::from(vec![1, 3]); |
1a4d82fc JJ |
489 | /// |
490 | /// assert_eq!(heap.pop(), Some(3)); | |
491 | /// assert_eq!(heap.pop(), Some(1)); | |
492 | /// assert_eq!(heap.pop(), None); | |
493 | /// ``` | |
85aaf69f | 494 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
495 | pub fn pop(&mut self) -> Option<T> { |
496 | self.data.pop().map(|mut item| { | |
497 | if !self.is_empty() { | |
498 | swap(&mut item, &mut self.data[0]); | |
9cc50fc6 | 499 | self.sift_down_to_bottom(0); |
1a4d82fc JJ |
500 | } |
501 | item | |
502 | }) | |
503 | } | |
504 | ||
505 | /// Pushes an item onto the binary heap. | |
506 | /// | |
507 | /// # Examples | |
508 | /// | |
54a0048b SL |
509 | /// Basic usage: |
510 | /// | |
1a4d82fc JJ |
511 | /// ``` |
512 | /// use std::collections::BinaryHeap; | |
513 | /// let mut heap = BinaryHeap::new(); | |
85aaf69f | 514 | /// heap.push(3); |
1a4d82fc JJ |
515 | /// heap.push(5); |
516 | /// heap.push(1); | |
517 | /// | |
518 | /// assert_eq!(heap.len(), 3); | |
519 | /// assert_eq!(heap.peek(), Some(&5)); | |
520 | /// ``` | |
85aaf69f | 521 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
522 | pub fn push(&mut self, item: T) { |
523 | let old_len = self.len(); | |
524 | self.data.push(item); | |
525 | self.sift_up(0, old_len); | |
526 | } | |
527 | ||
528 | /// Pushes an item onto the binary heap, then pops the greatest item off the queue in | |
529 | /// an optimized fashion. | |
530 | /// | |
531 | /// # Examples | |
532 | /// | |
54a0048b SL |
533 | /// Basic usage: |
534 | /// | |
1a4d82fc | 535 | /// ``` |
e9174d1e | 536 | /// #![feature(binary_heap_extras)] |
c1a9b12d | 537 | /// |
1a4d82fc JJ |
538 | /// use std::collections::BinaryHeap; |
539 | /// let mut heap = BinaryHeap::new(); | |
85aaf69f | 540 | /// heap.push(1); |
1a4d82fc JJ |
541 | /// heap.push(5); |
542 | /// | |
543 | /// assert_eq!(heap.push_pop(3), 5); | |
544 | /// assert_eq!(heap.push_pop(9), 9); | |
545 | /// assert_eq!(heap.len(), 2); | |
546 | /// assert_eq!(heap.peek(), Some(&3)); | |
547 | /// ``` | |
e9174d1e SL |
548 | #[unstable(feature = "binary_heap_extras", |
549 | reason = "needs to be audited", | |
550 | issue = "28147")] | |
1a4d82fc JJ |
551 | pub fn push_pop(&mut self, mut item: T) -> T { |
552 | match self.data.get_mut(0) { | |
553 | None => return item, | |
92a42be0 SL |
554 | Some(top) => { |
555 | if *top > item { | |
556 | swap(&mut item, top); | |
557 | } else { | |
558 | return item; | |
559 | } | |
560 | } | |
1a4d82fc JJ |
561 | } |
562 | ||
563 | self.sift_down(0); | |
564 | item | |
565 | } | |
566 | ||
567 | /// Pops the greatest item off the binary heap, then pushes an item onto the queue in | |
568 | /// an optimized fashion. The push is done regardless of whether the binary heap | |
569 | /// was empty. | |
570 | /// | |
571 | /// # Examples | |
572 | /// | |
54a0048b SL |
573 | /// Basic usage: |
574 | /// | |
1a4d82fc | 575 | /// ``` |
e9174d1e | 576 | /// #![feature(binary_heap_extras)] |
c1a9b12d | 577 | /// |
1a4d82fc JJ |
578 | /// use std::collections::BinaryHeap; |
579 | /// let mut heap = BinaryHeap::new(); | |
580 | /// | |
85aaf69f | 581 | /// assert_eq!(heap.replace(1), None); |
1a4d82fc JJ |
582 | /// assert_eq!(heap.replace(3), Some(1)); |
583 | /// assert_eq!(heap.len(), 1); | |
584 | /// assert_eq!(heap.peek(), Some(&3)); | |
585 | /// ``` | |
e9174d1e SL |
586 | #[unstable(feature = "binary_heap_extras", |
587 | reason = "needs to be audited", | |
588 | issue = "28147")] | |
1a4d82fc JJ |
589 | pub fn replace(&mut self, mut item: T) -> Option<T> { |
590 | if !self.is_empty() { | |
591 | swap(&mut item, &mut self.data[0]); | |
592 | self.sift_down(0); | |
593 | Some(item) | |
594 | } else { | |
595 | self.push(item); | |
596 | None | |
597 | } | |
598 | } | |
599 | ||
600 | /// Consumes the `BinaryHeap` and returns the underlying vector | |
601 | /// in arbitrary order. | |
602 | /// | |
603 | /// # Examples | |
604 | /// | |
54a0048b SL |
605 | /// Basic usage: |
606 | /// | |
1a4d82fc JJ |
607 | /// ``` |
608 | /// use std::collections::BinaryHeap; | |
b039eaaf | 609 | /// let heap = BinaryHeap::from(vec![1, 2, 3, 4, 5, 6, 7]); |
1a4d82fc JJ |
610 | /// let vec = heap.into_vec(); |
611 | /// | |
612 | /// // Will print in some order | |
62682a34 | 613 | /// for x in vec { |
1a4d82fc JJ |
614 | /// println!("{}", x); |
615 | /// } | |
616 | /// ``` | |
b039eaaf SL |
617 | #[stable(feature = "binary_heap_extras_15", since = "1.5.0")] |
618 | pub fn into_vec(self) -> Vec<T> { | |
619 | self.into() | |
620 | } | |
1a4d82fc JJ |
621 | |
622 | /// Consumes the `BinaryHeap` and returns a vector in sorted | |
623 | /// (ascending) order. | |
624 | /// | |
625 | /// # Examples | |
626 | /// | |
54a0048b SL |
627 | /// Basic usage: |
628 | /// | |
1a4d82fc JJ |
629 | /// ``` |
630 | /// use std::collections::BinaryHeap; | |
631 | /// | |
b039eaaf | 632 | /// let mut heap = BinaryHeap::from(vec![1, 2, 4, 5, 7]); |
1a4d82fc JJ |
633 | /// heap.push(6); |
634 | /// heap.push(3); | |
635 | /// | |
636 | /// let vec = heap.into_sorted_vec(); | |
c34b1796 | 637 | /// assert_eq!(vec, [1, 2, 3, 4, 5, 6, 7]); |
1a4d82fc | 638 | /// ``` |
b039eaaf | 639 | #[stable(feature = "binary_heap_extras_15", since = "1.5.0")] |
1a4d82fc JJ |
640 | pub fn into_sorted_vec(mut self) -> Vec<T> { |
641 | let mut end = self.len(); | |
642 | while end > 1 { | |
643 | end -= 1; | |
644 | self.data.swap(0, end); | |
645 | self.sift_down_range(0, end); | |
646 | } | |
647 | self.into_vec() | |
648 | } | |
649 | ||
650 | // The implementations of sift_up and sift_down use unsafe blocks in | |
651 | // order to move an element out of the vector (leaving behind a | |
d9579d0f AL |
652 | // hole), shift along the others and move the removed element back into the |
653 | // vector at the final location of the hole. | |
654 | // The `Hole` type is used to represent this, and make sure | |
655 | // the hole is filled back at the end of its scope, even on panic. | |
656 | // Using a hole reduces the constant factor compared to using swaps, | |
657 | // which involves twice as many moves. | |
658 | fn sift_up(&mut self, start: usize, pos: usize) { | |
1a4d82fc | 659 | unsafe { |
d9579d0f AL |
660 | // Take out the value at `pos` and create a hole. |
661 | let mut hole = Hole::new(&mut self.data, pos); | |
1a4d82fc | 662 | |
d9579d0f AL |
663 | while hole.pos() > start { |
664 | let parent = (hole.pos() - 1) / 2; | |
92a42be0 SL |
665 | if hole.element() <= hole.get(parent) { |
666 | break; | |
667 | } | |
d9579d0f | 668 | hole.move_to(parent); |
1a4d82fc | 669 | } |
1a4d82fc JJ |
670 | } |
671 | } | |
672 | ||
92a42be0 SL |
673 | /// Take an element at `pos` and move it down the heap, |
674 | /// while its children are larger. | |
675 | fn sift_down_range(&mut self, pos: usize, end: usize) { | |
1a4d82fc | 676 | unsafe { |
d9579d0f | 677 | let mut hole = Hole::new(&mut self.data, pos); |
1a4d82fc JJ |
678 | let mut child = 2 * pos + 1; |
679 | while child < end { | |
680 | let right = child + 1; | |
92a42be0 | 681 | // compare with the greater of the two children |
d9579d0f | 682 | if right < end && !(hole.get(child) > hole.get(right)) { |
1a4d82fc JJ |
683 | child = right; |
684 | } | |
92a42be0 SL |
685 | // if we are already in order, stop. |
686 | if hole.element() >= hole.get(child) { | |
687 | break; | |
688 | } | |
d9579d0f AL |
689 | hole.move_to(child); |
690 | child = 2 * hole.pos() + 1; | |
1a4d82fc | 691 | } |
1a4d82fc JJ |
692 | } |
693 | } | |
694 | ||
85aaf69f | 695 | fn sift_down(&mut self, pos: usize) { |
1a4d82fc JJ |
696 | let len = self.len(); |
697 | self.sift_down_range(pos, len); | |
698 | } | |
699 | ||
9cc50fc6 SL |
700 | /// Take an element at `pos` and move it all the way down the heap, |
701 | /// then sift it up to its position. | |
702 | /// | |
703 | /// Note: This is faster when the element is known to be large / should | |
704 | /// be closer to the bottom. | |
705 | fn sift_down_to_bottom(&mut self, mut pos: usize) { | |
706 | let end = self.len(); | |
707 | let start = pos; | |
708 | unsafe { | |
709 | let mut hole = Hole::new(&mut self.data, pos); | |
710 | let mut child = 2 * pos + 1; | |
711 | while child < end { | |
712 | let right = child + 1; | |
713 | // compare with the greater of the two children | |
714 | if right < end && !(hole.get(child) > hole.get(right)) { | |
715 | child = right; | |
716 | } | |
717 | hole.move_to(child); | |
718 | child = 2 * hole.pos() + 1; | |
719 | } | |
720 | pos = hole.pos; | |
721 | } | |
722 | self.sift_up(start, pos); | |
723 | } | |
724 | ||
1a4d82fc | 725 | /// Returns the length of the binary heap. |
54a0048b SL |
726 | /// |
727 | /// # Examples | |
728 | /// | |
729 | /// Basic usage: | |
730 | /// | |
731 | /// ``` | |
732 | /// use std::collections::BinaryHeap; | |
733 | /// let heap = BinaryHeap::from(vec![1, 3]); | |
734 | /// | |
735 | /// assert_eq!(heap.len(), 2); | |
736 | /// ``` | |
85aaf69f | 737 | #[stable(feature = "rust1", since = "1.0.0")] |
92a42be0 SL |
738 | pub fn len(&self) -> usize { |
739 | self.data.len() | |
740 | } | |
1a4d82fc JJ |
741 | |
742 | /// Checks if the binary heap is empty. | |
54a0048b SL |
743 | /// |
744 | /// # Examples | |
745 | /// | |
746 | /// Basic usage: | |
747 | /// | |
748 | /// ``` | |
749 | /// use std::collections::BinaryHeap; | |
750 | /// let mut heap = BinaryHeap::new(); | |
751 | /// | |
752 | /// assert!(heap.is_empty()); | |
753 | /// | |
754 | /// heap.push(3); | |
755 | /// heap.push(5); | |
756 | /// heap.push(1); | |
757 | /// | |
758 | /// assert!(!heap.is_empty()); | |
759 | /// ``` | |
85aaf69f | 760 | #[stable(feature = "rust1", since = "1.0.0")] |
92a42be0 SL |
761 | pub fn is_empty(&self) -> bool { |
762 | self.len() == 0 | |
763 | } | |
1a4d82fc JJ |
764 | |
765 | /// Clears the binary heap, returning an iterator over the removed elements. | |
c34b1796 AL |
766 | /// |
767 | /// The elements are removed in arbitrary order. | |
54a0048b SL |
768 | /// |
769 | /// # Examples | |
770 | /// | |
771 | /// Basic usage: | |
772 | /// | |
773 | /// ``` | |
774 | /// use std::collections::BinaryHeap; | |
775 | /// let mut heap = BinaryHeap::from(vec![1, 3]); | |
776 | /// | |
777 | /// assert!(!heap.is_empty()); | |
778 | /// | |
779 | /// for x in heap.drain() { | |
780 | /// println!("{}", x); | |
781 | /// } | |
782 | /// | |
783 | /// assert!(heap.is_empty()); | |
784 | /// ``` | |
1a4d82fc | 785 | #[inline] |
92a42be0 | 786 | #[stable(feature = "drain", since = "1.6.0")] |
1a4d82fc | 787 | pub fn drain(&mut self) -> Drain<T> { |
d9579d0f | 788 | Drain { iter: self.data.drain(..) } |
1a4d82fc JJ |
789 | } |
790 | ||
791 | /// Drops all items from the binary heap. | |
54a0048b SL |
792 | /// |
793 | /// # Examples | |
794 | /// | |
795 | /// Basic usage: | |
796 | /// | |
797 | /// ``` | |
798 | /// use std::collections::BinaryHeap; | |
799 | /// let mut heap = BinaryHeap::from(vec![1, 3]); | |
800 | /// | |
801 | /// assert!(!heap.is_empty()); | |
802 | /// | |
803 | /// heap.clear(); | |
804 | /// | |
805 | /// assert!(heap.is_empty()); | |
806 | /// ``` | |
85aaf69f | 807 | #[stable(feature = "rust1", since = "1.0.0")] |
92a42be0 SL |
808 | pub fn clear(&mut self) { |
809 | self.drain(); | |
810 | } | |
a7813a04 XL |
811 | |
812 | fn rebuild(&mut self) { | |
813 | let mut n = self.len() / 2; | |
814 | while n > 0 { | |
815 | n -= 1; | |
816 | self.sift_down(n); | |
817 | } | |
818 | } | |
819 | ||
820 | /// Moves all the elements of `other` into `self`, leaving `other` empty. | |
821 | /// | |
822 | /// # Examples | |
823 | /// | |
824 | /// Basic usage: | |
825 | /// | |
826 | /// ``` | |
a7813a04 XL |
827 | /// use std::collections::BinaryHeap; |
828 | /// | |
829 | /// let v = vec![-10, 1, 2, 3, 3]; | |
830 | /// let mut a = BinaryHeap::from(v); | |
831 | /// | |
832 | /// let v = vec![-20, 5, 43]; | |
833 | /// let mut b = BinaryHeap::from(v); | |
834 | /// | |
835 | /// a.append(&mut b); | |
836 | /// | |
837 | /// assert_eq!(a.into_sorted_vec(), [-20, -10, 1, 2, 3, 3, 5, 43]); | |
838 | /// assert!(b.is_empty()); | |
839 | /// ``` | |
3157f602 | 840 | #[stable(feature = "binary_heap_append", since = "1.11.0")] |
a7813a04 XL |
841 | pub fn append(&mut self, other: &mut Self) { |
842 | if self.len() < other.len() { | |
843 | swap(self, other); | |
844 | } | |
845 | ||
846 | if other.is_empty() { | |
847 | return; | |
848 | } | |
849 | ||
850 | #[inline(always)] | |
851 | fn log2_fast(x: usize) -> usize { | |
852 | 8 * size_of::<usize>() - (x.leading_zeros() as usize) - 1 | |
853 | } | |
854 | ||
855 | // `rebuild` takes O(len1 + len2) operations | |
856 | // and about 2 * (len1 + len2) comparisons in the worst case | |
857 | // while `extend` takes O(len2 * log_2(len1)) operations | |
858 | // and about 1 * len2 * log_2(len1) comparisons in the worst case, | |
859 | // assuming len1 >= len2. | |
860 | #[inline] | |
861 | fn better_to_rebuild(len1: usize, len2: usize) -> bool { | |
862 | 2 * (len1 + len2) < len2 * log2_fast(len1) | |
863 | } | |
864 | ||
865 | if better_to_rebuild(self.len(), other.len()) { | |
866 | self.data.append(&mut other.data); | |
867 | self.rebuild(); | |
868 | } else { | |
869 | self.extend(other.drain()); | |
870 | } | |
871 | } | |
1a4d82fc JJ |
872 | } |
873 | ||
d9579d0f AL |
874 | /// Hole represents a hole in a slice i.e. an index without valid value |
875 | /// (because it was moved from or duplicated). | |
876 | /// In drop, `Hole` will restore the slice by filling the hole | |
877 | /// position with the value that was originally removed. | |
878 | struct Hole<'a, T: 'a> { | |
879 | data: &'a mut [T], | |
880 | /// `elt` is always `Some` from new until drop. | |
881 | elt: Option<T>, | |
882 | pos: usize, | |
883 | } | |
884 | ||
885 | impl<'a, T> Hole<'a, T> { | |
886 | /// Create a new Hole at index `pos`. | |
887 | fn new(data: &'a mut [T], pos: usize) -> Self { | |
888 | unsafe { | |
889 | let elt = ptr::read(&data[pos]); | |
890 | Hole { | |
891 | data: data, | |
892 | elt: Some(elt), | |
893 | pos: pos, | |
894 | } | |
895 | } | |
896 | } | |
897 | ||
898 | #[inline(always)] | |
92a42be0 SL |
899 | fn pos(&self) -> usize { |
900 | self.pos | |
901 | } | |
d9579d0f AL |
902 | |
903 | /// Return a reference to the element removed | |
904 | #[inline(always)] | |
92a42be0 | 905 | fn element(&self) -> &T { |
d9579d0f AL |
906 | self.elt.as_ref().unwrap() |
907 | } | |
908 | ||
909 | /// Return a reference to the element at `index`. | |
910 | /// | |
911 | /// Panics if the index is out of bounds. | |
912 | /// | |
913 | /// Unsafe because index must not equal pos. | |
914 | #[inline(always)] | |
915 | unsafe fn get(&self, index: usize) -> &T { | |
916 | debug_assert!(index != self.pos); | |
917 | &self.data[index] | |
918 | } | |
919 | ||
920 | /// Move hole to new location | |
921 | /// | |
922 | /// Unsafe because index must not equal pos. | |
923 | #[inline(always)] | |
924 | unsafe fn move_to(&mut self, index: usize) { | |
925 | debug_assert!(index != self.pos); | |
926 | let index_ptr: *const _ = &self.data[index]; | |
927 | let hole_ptr = &mut self.data[self.pos]; | |
928 | ptr::copy_nonoverlapping(index_ptr, hole_ptr, 1); | |
929 | self.pos = index; | |
930 | } | |
931 | } | |
932 | ||
933 | impl<'a, T> Drop for Hole<'a, T> { | |
934 | fn drop(&mut self) { | |
935 | // fill the hole again | |
936 | unsafe { | |
937 | let pos = self.pos; | |
938 | ptr::write(&mut self.data[pos], self.elt.take().unwrap()); | |
939 | } | |
940 | } | |
941 | } | |
942 | ||
1a4d82fc | 943 | /// `BinaryHeap` iterator. |
85aaf69f | 944 | #[stable(feature = "rust1", since = "1.0.0")] |
92a42be0 | 945 | pub struct Iter<'a, T: 'a> { |
1a4d82fc JJ |
946 | iter: slice::Iter<'a, T>, |
947 | } | |
948 | ||
949 | // FIXME(#19839) Remove in favor of `#[derive(Clone)]` | |
85aaf69f | 950 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
951 | impl<'a, T> Clone for Iter<'a, T> { |
952 | fn clone(&self) -> Iter<'a, T> { | |
953 | Iter { iter: self.iter.clone() } | |
954 | } | |
955 | } | |
956 | ||
85aaf69f | 957 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
958 | impl<'a, T> Iterator for Iter<'a, T> { |
959 | type Item = &'a T; | |
960 | ||
961 | #[inline] | |
92a42be0 SL |
962 | fn next(&mut self) -> Option<&'a T> { |
963 | self.iter.next() | |
964 | } | |
1a4d82fc JJ |
965 | |
966 | #[inline] | |
92a42be0 SL |
967 | fn size_hint(&self) -> (usize, Option<usize>) { |
968 | self.iter.size_hint() | |
969 | } | |
1a4d82fc JJ |
970 | } |
971 | ||
85aaf69f | 972 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
973 | impl<'a, T> DoubleEndedIterator for Iter<'a, T> { |
974 | #[inline] | |
92a42be0 SL |
975 | fn next_back(&mut self) -> Option<&'a T> { |
976 | self.iter.next_back() | |
977 | } | |
1a4d82fc JJ |
978 | } |
979 | ||
85aaf69f | 980 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
981 | impl<'a, T> ExactSizeIterator for Iter<'a, T> {} |
982 | ||
983 | /// An iterator that moves out of a `BinaryHeap`. | |
85aaf69f | 984 | #[stable(feature = "rust1", since = "1.0.0")] |
a7813a04 | 985 | #[derive(Clone)] |
1a4d82fc JJ |
986 | pub struct IntoIter<T> { |
987 | iter: vec::IntoIter<T>, | |
988 | } | |
989 | ||
85aaf69f | 990 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
991 | impl<T> Iterator for IntoIter<T> { |
992 | type Item = T; | |
993 | ||
994 | #[inline] | |
92a42be0 SL |
995 | fn next(&mut self) -> Option<T> { |
996 | self.iter.next() | |
997 | } | |
1a4d82fc JJ |
998 | |
999 | #[inline] | |
92a42be0 SL |
1000 | fn size_hint(&self) -> (usize, Option<usize>) { |
1001 | self.iter.size_hint() | |
1002 | } | |
1a4d82fc JJ |
1003 | } |
1004 | ||
85aaf69f | 1005 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
1006 | impl<T> DoubleEndedIterator for IntoIter<T> { |
1007 | #[inline] | |
92a42be0 SL |
1008 | fn next_back(&mut self) -> Option<T> { |
1009 | self.iter.next_back() | |
1010 | } | |
1a4d82fc JJ |
1011 | } |
1012 | ||
85aaf69f | 1013 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
1014 | impl<T> ExactSizeIterator for IntoIter<T> {} |
1015 | ||
1016 | /// An iterator that drains a `BinaryHeap`. | |
92a42be0 | 1017 | #[stable(feature = "drain", since = "1.6.0")] |
1a4d82fc JJ |
1018 | pub struct Drain<'a, T: 'a> { |
1019 | iter: vec::Drain<'a, T>, | |
1020 | } | |
1021 | ||
85aaf69f | 1022 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
1023 | impl<'a, T: 'a> Iterator for Drain<'a, T> { |
1024 | type Item = T; | |
1025 | ||
1026 | #[inline] | |
92a42be0 SL |
1027 | fn next(&mut self) -> Option<T> { |
1028 | self.iter.next() | |
1029 | } | |
1a4d82fc JJ |
1030 | |
1031 | #[inline] | |
92a42be0 SL |
1032 | fn size_hint(&self) -> (usize, Option<usize>) { |
1033 | self.iter.size_hint() | |
1034 | } | |
1a4d82fc JJ |
1035 | } |
1036 | ||
85aaf69f | 1037 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
1038 | impl<'a, T: 'a> DoubleEndedIterator for Drain<'a, T> { |
1039 | #[inline] | |
92a42be0 SL |
1040 | fn next_back(&mut self) -> Option<T> { |
1041 | self.iter.next_back() | |
1042 | } | |
1a4d82fc JJ |
1043 | } |
1044 | ||
85aaf69f | 1045 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
1046 | impl<'a, T: 'a> ExactSizeIterator for Drain<'a, T> {} |
1047 | ||
92a42be0 | 1048 | #[stable(feature = "rust1", since = "1.0.0")] |
b039eaaf SL |
1049 | impl<T: Ord> From<Vec<T>> for BinaryHeap<T> { |
1050 | fn from(vec: Vec<T>) -> BinaryHeap<T> { | |
1051 | let mut heap = BinaryHeap { data: vec }; | |
a7813a04 | 1052 | heap.rebuild(); |
b039eaaf SL |
1053 | heap |
1054 | } | |
1055 | } | |
1056 | ||
92a42be0 | 1057 | #[stable(feature = "rust1", since = "1.0.0")] |
b039eaaf SL |
1058 | impl<T> From<BinaryHeap<T>> for Vec<T> { |
1059 | fn from(heap: BinaryHeap<T>) -> Vec<T> { | |
1060 | heap.data | |
1061 | } | |
1062 | } | |
1063 | ||
85aaf69f | 1064 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 1065 | impl<T: Ord> FromIterator<T> for BinaryHeap<T> { |
92a42be0 | 1066 | fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> BinaryHeap<T> { |
b039eaaf | 1067 | BinaryHeap::from(iter.into_iter().collect::<Vec<_>>()) |
85aaf69f SL |
1068 | } |
1069 | } | |
1070 | ||
1071 | #[stable(feature = "rust1", since = "1.0.0")] | |
1072 | impl<T: Ord> IntoIterator for BinaryHeap<T> { | |
1073 | type Item = T; | |
1074 | type IntoIter = IntoIter<T>; | |
1075 | ||
9346a6ac AL |
1076 | /// Creates a consuming iterator, that is, one that moves each value out of |
1077 | /// the binary heap in arbitrary order. The binary heap cannot be used | |
1078 | /// after calling this. | |
1079 | /// | |
1080 | /// # Examples | |
1081 | /// | |
54a0048b SL |
1082 | /// Basic usage: |
1083 | /// | |
9346a6ac | 1084 | /// ``` |
9346a6ac | 1085 | /// use std::collections::BinaryHeap; |
b039eaaf | 1086 | /// let heap = BinaryHeap::from(vec![1, 2, 3, 4]); |
9346a6ac AL |
1087 | /// |
1088 | /// // Print 1, 2, 3, 4 in arbitrary order | |
1089 | /// for x in heap.into_iter() { | |
1090 | /// // x has type i32, not &i32 | |
1091 | /// println!("{}", x); | |
1092 | /// } | |
1093 | /// ``` | |
85aaf69f | 1094 | fn into_iter(self) -> IntoIter<T> { |
9346a6ac | 1095 | IntoIter { iter: self.data.into_iter() } |
85aaf69f SL |
1096 | } |
1097 | } | |
1098 | ||
1099 | #[stable(feature = "rust1", since = "1.0.0")] | |
1100 | impl<'a, T> IntoIterator for &'a BinaryHeap<T> where T: Ord { | |
1101 | type Item = &'a T; | |
1102 | type IntoIter = Iter<'a, T>; | |
1103 | ||
1104 | fn into_iter(self) -> Iter<'a, T> { | |
1105 | self.iter() | |
1a4d82fc JJ |
1106 | } |
1107 | } | |
1108 | ||
85aaf69f | 1109 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 1110 | impl<T: Ord> Extend<T> for BinaryHeap<T> { |
a7813a04 | 1111 | #[inline] |
54a0048b | 1112 | fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I) { |
a7813a04 XL |
1113 | <Self as SpecExtend<I>>::spec_extend(self, iter); |
1114 | } | |
1115 | } | |
1116 | ||
1117 | impl<T: Ord, I: IntoIterator<Item = T>> SpecExtend<I> for BinaryHeap<T> { | |
1118 | default fn spec_extend(&mut self, iter: I) { | |
1119 | self.extend_desugared(iter.into_iter()); | |
1120 | } | |
1121 | } | |
1122 | ||
1123 | impl<T: Ord> SpecExtend<BinaryHeap<T>> for BinaryHeap<T> { | |
1124 | fn spec_extend(&mut self, ref mut other: BinaryHeap<T>) { | |
1125 | self.append(other); | |
1126 | } | |
1127 | } | |
1128 | ||
1129 | impl<T: Ord> BinaryHeap<T> { | |
1130 | fn extend_desugared<I: IntoIterator<Item = T>>(&mut self, iter: I) { | |
54a0048b SL |
1131 | let iterator = iter.into_iter(); |
1132 | let (lower, _) = iterator.size_hint(); | |
1a4d82fc JJ |
1133 | |
1134 | self.reserve(lower); | |
1135 | ||
54a0048b | 1136 | for elem in iterator { |
1a4d82fc JJ |
1137 | self.push(elem); |
1138 | } | |
1139 | } | |
1140 | } | |
62682a34 SL |
1141 | |
1142 | #[stable(feature = "extend_ref", since = "1.2.0")] | |
1143 | impl<'a, T: 'a + Ord + Copy> Extend<&'a T> for BinaryHeap<T> { | |
92a42be0 | 1144 | fn extend<I: IntoIterator<Item = &'a T>>(&mut self, iter: I) { |
62682a34 SL |
1145 | self.extend(iter.into_iter().cloned()); |
1146 | } | |
1147 | } |