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1 | // Copyright 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 | ||
7453a54e SL |
11 | //! A contiguous growable array type with heap-allocated contents, written |
12 | //! `Vec<T>` but pronounced 'vector.' | |
1a4d82fc | 13 | //! |
62682a34 SL |
14 | //! Vectors have `O(1)` indexing, amortized `O(1)` push (to the end) and |
15 | //! `O(1)` pop (from the end). | |
1a4d82fc JJ |
16 | //! |
17 | //! # Examples | |
18 | //! | |
cc61c64b | 19 | //! You can explicitly create a [`Vec<T>`] with [`new`]: |
1a4d82fc JJ |
20 | //! |
21 | //! ``` | |
d9579d0f | 22 | //! let v: Vec<i32> = Vec::new(); |
1a4d82fc JJ |
23 | //! ``` |
24 | //! | |
c30ab7b3 | 25 | //! ...or by using the [`vec!`] macro: |
1a4d82fc JJ |
26 | //! |
27 | //! ``` | |
d9579d0f | 28 | //! let v: Vec<i32> = vec![]; |
1a4d82fc | 29 | //! |
d9579d0f AL |
30 | //! let v = vec![1, 2, 3, 4, 5]; |
31 | //! | |
32 | //! let v = vec![0; 10]; // ten zeroes | |
1a4d82fc JJ |
33 | //! ``` |
34 | //! | |
c30ab7b3 | 35 | //! You can [`push`] values onto the end of a vector (which will grow the vector |
e9174d1e | 36 | //! as needed): |
1a4d82fc JJ |
37 | //! |
38 | //! ``` | |
d9579d0f | 39 | //! let mut v = vec![1, 2]; |
1a4d82fc | 40 | //! |
d9579d0f | 41 | //! v.push(3); |
1a4d82fc JJ |
42 | //! ``` |
43 | //! | |
d9579d0f AL |
44 | //! Popping values works in much the same way: |
45 | //! | |
46 | //! ``` | |
47 | //! let mut v = vec![1, 2]; | |
1a4d82fc | 48 | //! |
d9579d0f | 49 | //! let two = v.pop(); |
1a4d82fc | 50 | //! ``` |
1a4d82fc | 51 | //! |
c30ab7b3 | 52 | //! Vectors also support indexing (through the [`Index`] and [`IndexMut`] traits): |
d9579d0f AL |
53 | //! |
54 | //! ``` | |
55 | //! let mut v = vec![1, 2, 3]; | |
56 | //! let three = v[2]; | |
57 | //! v[1] = v[1] + 5; | |
1a4d82fc | 58 | //! ``` |
c30ab7b3 SL |
59 | //! |
60 | //! [`Vec<T>`]: ../../std/vec/struct.Vec.html | |
cc61c64b | 61 | //! [`new`]: ../../std/vec/struct.Vec.html#method.new |
c30ab7b3 SL |
62 | //! [`push`]: ../../std/vec/struct.Vec.html#method.push |
63 | //! [`Index`]: ../../std/ops/trait.Index.html | |
64 | //! [`IndexMut`]: ../../std/ops/trait.IndexMut.html | |
65 | //! [`vec!`]: ../../std/macro.vec.html | |
1a4d82fc | 66 | |
85aaf69f | 67 | #![stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 68 | |
1a4d82fc | 69 | use alloc::boxed::Box; |
7453a54e SL |
70 | use alloc::raw_vec::RawVec; |
71 | use borrow::ToOwned; | |
54a0048b | 72 | use borrow::Cow; |
c34b1796 | 73 | use core::cmp::Ordering; |
1a4d82fc JJ |
74 | use core::fmt; |
75 | use core::hash::{self, Hash}; | |
54a0048b | 76 | use core::intrinsics::{arith_offset, assume}; |
c30ab7b3 | 77 | use core::iter::{FromIterator, FusedIterator, TrustedLen}; |
1a4d82fc | 78 | use core::mem; |
cc61c64b XL |
79 | #[cfg(not(test))] |
80 | use core::num::Float; | |
32a655c1 | 81 | use core::ops::{InPlace, Index, IndexMut, Place, Placer}; |
1a4d82fc JJ |
82 | use core::ops; |
83 | use core::ptr; | |
5bcae85e | 84 | use core::ptr::Shared; |
85aaf69f | 85 | use core::slice; |
85aaf69f | 86 | |
d9579d0f | 87 | use super::range::RangeArgument; |
32a655c1 | 88 | use Bound::{Excluded, Included, Unbounded}; |
d9579d0f | 89 | |
c30ab7b3 | 90 | /// A contiguous growable array type, written `Vec<T>` but pronounced 'vector'. |
1a4d82fc JJ |
91 | /// |
92 | /// # Examples | |
93 | /// | |
94 | /// ``` | |
95 | /// let mut vec = Vec::new(); | |
85aaf69f SL |
96 | /// vec.push(1); |
97 | /// vec.push(2); | |
1a4d82fc JJ |
98 | /// |
99 | /// assert_eq!(vec.len(), 2); | |
100 | /// assert_eq!(vec[0], 1); | |
101 | /// | |
102 | /// assert_eq!(vec.pop(), Some(2)); | |
103 | /// assert_eq!(vec.len(), 1); | |
104 | /// | |
85aaf69f | 105 | /// vec[0] = 7; |
1a4d82fc JJ |
106 | /// assert_eq!(vec[0], 7); |
107 | /// | |
62682a34 | 108 | /// vec.extend([1, 2, 3].iter().cloned()); |
1a4d82fc | 109 | /// |
62682a34 | 110 | /// for x in &vec { |
1a4d82fc JJ |
111 | /// println!("{}", x); |
112 | /// } | |
c34b1796 | 113 | /// assert_eq!(vec, [7, 1, 2, 3]); |
1a4d82fc JJ |
114 | /// ``` |
115 | /// | |
c30ab7b3 | 116 | /// The [`vec!`] macro is provided to make initialization more convenient: |
1a4d82fc JJ |
117 | /// |
118 | /// ``` | |
85aaf69f | 119 | /// let mut vec = vec![1, 2, 3]; |
1a4d82fc | 120 | /// vec.push(4); |
c34b1796 | 121 | /// assert_eq!(vec, [1, 2, 3, 4]); |
1a4d82fc JJ |
122 | /// ``` |
123 | /// | |
c1a9b12d SL |
124 | /// It can also initialize each element of a `Vec<T>` with a given value: |
125 | /// | |
126 | /// ``` | |
127 | /// let vec = vec![0; 5]; | |
128 | /// assert_eq!(vec, [0, 0, 0, 0, 0]); | |
129 | /// ``` | |
130 | /// | |
1a4d82fc JJ |
131 | /// Use a `Vec<T>` as an efficient stack: |
132 | /// | |
133 | /// ``` | |
134 | /// let mut stack = Vec::new(); | |
135 | /// | |
85aaf69f SL |
136 | /// stack.push(1); |
137 | /// stack.push(2); | |
138 | /// stack.push(3); | |
1a4d82fc | 139 | /// |
bd371182 | 140 | /// while let Some(top) = stack.pop() { |
1a4d82fc JJ |
141 | /// // Prints 3, 2, 1 |
142 | /// println!("{}", top); | |
143 | /// } | |
144 | /// ``` | |
145 | /// | |
7453a54e SL |
146 | /// # Indexing |
147 | /// | |
c30ab7b3 SL |
148 | /// The `Vec` type allows to access values by index, because it implements the |
149 | /// [`Index`] trait. An example will be more explicit: | |
7453a54e SL |
150 | /// |
151 | /// ``` | |
c30ab7b3 | 152 | /// let v = vec![0, 2, 4, 6]; |
7453a54e SL |
153 | /// println!("{}", v[1]); // it will display '2' |
154 | /// ``` | |
155 | /// | |
c30ab7b3 | 156 | /// However be careful: if you try to access an index which isn't in the `Vec`, |
7453a54e SL |
157 | /// your software will panic! You cannot do this: |
158 | /// | |
159 | /// ```ignore | |
c30ab7b3 | 160 | /// let v = vec![0, 2, 4, 6]; |
7453a54e SL |
161 | /// println!("{}", v[6]); // it will panic! |
162 | /// ``` | |
163 | /// | |
164 | /// In conclusion: always check if the index you want to get really exists | |
165 | /// before doing it. | |
166 | /// | |
167 | /// # Slicing | |
168 | /// | |
c30ab7b3 SL |
169 | /// A `Vec` can be mutable. Slices, on the other hand, are read-only objects. |
170 | /// To get a slice, use `&`. Example: | |
7453a54e SL |
171 | /// |
172 | /// ``` | |
173 | /// fn read_slice(slice: &[usize]) { | |
174 | /// // ... | |
175 | /// } | |
176 | /// | |
c30ab7b3 | 177 | /// let v = vec![0, 1]; |
7453a54e SL |
178 | /// read_slice(&v); |
179 | /// | |
180 | /// // ... and that's all! | |
181 | /// // you can also do it like this: | |
182 | /// let x : &[usize] = &v; | |
183 | /// ``` | |
184 | /// | |
185 | /// In Rust, it's more common to pass slices as arguments rather than vectors | |
c30ab7b3 SL |
186 | /// when you just want to provide a read access. The same goes for [`String`] and |
187 | /// [`&str`]. | |
7453a54e | 188 | /// |
1a4d82fc JJ |
189 | /// # Capacity and reallocation |
190 | /// | |
c34b1796 AL |
191 | /// The capacity of a vector is the amount of space allocated for any future |
192 | /// elements that will be added onto the vector. This is not to be confused with | |
193 | /// the *length* of a vector, which specifies the number of actual elements | |
194 | /// within the vector. If a vector's length exceeds its capacity, its capacity | |
195 | /// will automatically be increased, but its elements will have to be | |
1a4d82fc JJ |
196 | /// reallocated. |
197 | /// | |
c34b1796 AL |
198 | /// For example, a vector with capacity 10 and length 0 would be an empty vector |
199 | /// with space for 10 more elements. Pushing 10 or fewer elements onto the | |
200 | /// vector will not change its capacity or cause reallocation to occur. However, | |
201 | /// if the vector's length is increased to 11, it will have to reallocate, which | |
c30ab7b3 | 202 | /// can be slow. For this reason, it is recommended to use [`Vec::with_capacity`] |
c34b1796 | 203 | /// whenever possible to specify how big the vector is expected to get. |
b039eaaf SL |
204 | /// |
205 | /// # Guarantees | |
206 | /// | |
c30ab7b3 | 207 | /// Due to its incredibly fundamental nature, `Vec` makes a lot of guarantees |
b039eaaf SL |
208 | /// about its design. This ensures that it's as low-overhead as possible in |
209 | /// the general case, and can be correctly manipulated in primitive ways | |
210 | /// by unsafe code. Note that these guarantees refer to an unqualified `Vec<T>`. | |
211 | /// If additional type parameters are added (e.g. to support custom allocators), | |
212 | /// overriding their defaults may change the behavior. | |
213 | /// | |
c30ab7b3 | 214 | /// Most fundamentally, `Vec` is and always will be a (pointer, capacity, length) |
b039eaaf SL |
215 | /// triplet. No more, no less. The order of these fields is completely |
216 | /// unspecified, and you should use the appropriate methods to modify these. | |
217 | /// The pointer will never be null, so this type is null-pointer-optimized. | |
218 | /// | |
219 | /// However, the pointer may not actually point to allocated memory. In particular, | |
cc61c64b XL |
220 | /// if you construct a `Vec` with capacity 0 via [`Vec::new`], [`vec![]`][`vec!`], |
221 | /// [`Vec::with_capacity(0)`][`Vec::with_capacity`], or by calling [`shrink_to_fit`] | |
c30ab7b3 SL |
222 | /// on an empty Vec, it will not allocate memory. Similarly, if you store zero-sized |
223 | /// types inside a `Vec`, it will not allocate space for them. *Note that in this case | |
cc61c64b XL |
224 | /// the `Vec` may not report a [`capacity`] of 0*. `Vec` will allocate if and only |
225 | /// if [`mem::size_of::<T>`]` * capacity() > 0`. In general, `Vec`'s allocation | |
b039eaaf | 226 | /// details are subtle enough that it is strongly recommended that you only |
c30ab7b3 | 227 | /// free memory allocated by a `Vec` by creating a new `Vec` and dropping it. |
b039eaaf | 228 | /// |
c30ab7b3 | 229 | /// If a `Vec` *has* allocated memory, then the memory it points to is on the heap |
b039eaaf | 230 | /// (as defined by the allocator Rust is configured to use by default), and its |
cc61c64b XL |
231 | /// pointer points to [`len`] initialized elements in order (what you would see |
232 | /// if you coerced it to a slice), followed by [`capacity`]` - `[`len`] | |
c30ab7b3 | 233 | /// logically uninitialized elements. |
b039eaaf | 234 | /// |
c30ab7b3 | 235 | /// `Vec` will never perform a "small optimization" where elements are actually |
b039eaaf SL |
236 | /// stored on the stack for two reasons: |
237 | /// | |
238 | /// * It would make it more difficult for unsafe code to correctly manipulate | |
c30ab7b3 SL |
239 | /// a `Vec`. The contents of a `Vec` wouldn't have a stable address if it were |
240 | /// only moved, and it would be more difficult to determine if a `Vec` had | |
b039eaaf SL |
241 | /// actually allocated memory. |
242 | /// | |
243 | /// * It would penalize the general case, incurring an additional branch | |
244 | /// on every access. | |
245 | /// | |
c30ab7b3 SL |
246 | /// `Vec` will never automatically shrink itself, even if completely empty. This |
247 | /// ensures no unnecessary allocations or deallocations occur. Emptying a `Vec` | |
cc61c64b | 248 | /// and then filling it back up to the same [`len`] should incur no calls to |
c30ab7b3 | 249 | /// the allocator. If you wish to free up unused memory, use |
cc61c64b | 250 | /// [`shrink_to_fit`][`shrink_to_fit`]. |
b039eaaf | 251 | /// |
c30ab7b3 SL |
252 | /// [`push`] and [`insert`] will never (re)allocate if the reported capacity is |
253 | /// sufficient. [`push`] and [`insert`] *will* (re)allocate if | |
cc61c64b | 254 | /// [`len`]` == `[`capacity`]. That is, the reported capacity is completely |
c30ab7b3 SL |
255 | /// accurate, and can be relied on. It can even be used to manually free the memory |
256 | /// allocated by a `Vec` if desired. Bulk insertion methods *may* reallocate, even | |
257 | /// when not necessary. | |
b039eaaf | 258 | /// |
c30ab7b3 SL |
259 | /// `Vec` does not guarantee any particular growth strategy when reallocating |
260 | /// when full, nor when [`reserve`] is called. The current strategy is basic | |
b039eaaf | 261 | /// and it may prove desirable to use a non-constant growth factor. Whatever |
c30ab7b3 | 262 | /// strategy is used will of course guarantee `O(1)` amortized [`push`]. |
b039eaaf | 263 | /// |
c30ab7b3 SL |
264 | /// `vec![x; n]`, `vec![a, b, c, d]`, and |
265 | /// [`Vec::with_capacity(n)`][`Vec::with_capacity`], will all produce a `Vec` | |
cc61c64b | 266 | /// with exactly the requested capacity. If [`len`]` == `[`capacity`], |
c30ab7b3 SL |
267 | /// (as is the case for the [`vec!`] macro), then a `Vec<T>` can be converted to |
268 | /// and from a [`Box<[T]>`][owned slice] without reallocating or moving the elements. | |
b039eaaf | 269 | /// |
c30ab7b3 | 270 | /// `Vec` will not specifically overwrite any data that is removed from it, |
b039eaaf SL |
271 | /// but also won't specifically preserve it. Its uninitialized memory is |
272 | /// scratch space that it may use however it wants. It will generally just do | |
273 | /// whatever is most efficient or otherwise easy to implement. Do not rely on | |
c30ab7b3 SL |
274 | /// removed data to be erased for security purposes. Even if you drop a `Vec`, its |
275 | /// buffer may simply be reused by another `Vec`. Even if you zero a `Vec`'s memory | |
b039eaaf | 276 | /// first, that may not actually happen because the optimizer does not consider |
7cac9316 XL |
277 | /// this a side-effect that must be preserved. There is one case which we will |
278 | /// not break, however: using `unsafe` code to write to the excess capacity, | |
279 | /// and then increasing the length to match, is always valid. | |
b039eaaf | 280 | /// |
c30ab7b3 | 281 | /// `Vec` does not currently guarantee the order in which elements are dropped |
b039eaaf SL |
282 | /// (the order has changed in the past, and may change again). |
283 | /// | |
c30ab7b3 SL |
284 | /// [`vec!`]: ../../std/macro.vec.html |
285 | /// [`Index`]: ../../std/ops/trait.Index.html | |
286 | /// [`String`]: ../../std/string/struct.String.html | |
287 | /// [`&str`]: ../../std/primitive.str.html | |
288 | /// [`Vec::with_capacity`]: ../../std/vec/struct.Vec.html#method.with_capacity | |
cc61c64b XL |
289 | /// [`Vec::new`]: ../../std/vec/struct.Vec.html#method.new |
290 | /// [`shrink_to_fit`]: ../../std/vec/struct.Vec.html#method.shrink_to_fit | |
291 | /// [`capacity`]: ../../std/vec/struct.Vec.html#method.capacity | |
292 | /// [`mem::size_of::<T>`]: ../../std/mem/fn.size_of.html | |
293 | /// [`len`]: ../../std/vec/struct.Vec.html#method.len | |
c30ab7b3 SL |
294 | /// [`push`]: ../../std/vec/struct.Vec.html#method.push |
295 | /// [`insert`]: ../../std/vec/struct.Vec.html#method.insert | |
296 | /// [`reserve`]: ../../std/vec/struct.Vec.html#method.reserve | |
297 | /// [owned slice]: ../../std/boxed/struct.Box.html | |
85aaf69f | 298 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 299 | pub struct Vec<T> { |
c1a9b12d | 300 | buf: RawVec<T>, |
85aaf69f | 301 | len: usize, |
1a4d82fc JJ |
302 | } |
303 | ||
1a4d82fc JJ |
304 | //////////////////////////////////////////////////////////////////////////////// |
305 | // Inherent methods | |
306 | //////////////////////////////////////////////////////////////////////////////// | |
307 | ||
308 | impl<T> Vec<T> { | |
309 | /// Constructs a new, empty `Vec<T>`. | |
310 | /// | |
311 | /// The vector will not allocate until elements are pushed onto it. | |
312 | /// | |
313 | /// # Examples | |
314 | /// | |
315 | /// ``` | |
92a42be0 | 316 | /// # #![allow(unused_mut)] |
85aaf69f | 317 | /// let mut vec: Vec<i32> = Vec::new(); |
1a4d82fc JJ |
318 | /// ``` |
319 | #[inline] | |
85aaf69f | 320 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 321 | pub fn new() -> Vec<T> { |
92a42be0 SL |
322 | Vec { |
323 | buf: RawVec::new(), | |
324 | len: 0, | |
325 | } | |
1a4d82fc JJ |
326 | } |
327 | ||
328 | /// Constructs a new, empty `Vec<T>` with the specified capacity. | |
329 | /// | |
e9174d1e SL |
330 | /// The vector will be able to hold exactly `capacity` elements without |
331 | /// reallocating. If `capacity` is 0, the vector will not allocate. | |
1a4d82fc | 332 | /// |
e9174d1e | 333 | /// It is important to note that this function does not specify the *length* |
c30ab7b3 SL |
334 | /// of the returned vector, but only the *capacity*. For an explanation of |
335 | /// the difference between length and capacity, see *[Capacity and reallocation]*. | |
336 | /// | |
337 | /// [Capacity and reallocation]: #capacity-and-reallocation | |
1a4d82fc JJ |
338 | /// |
339 | /// # Examples | |
340 | /// | |
341 | /// ``` | |
9346a6ac | 342 | /// let mut vec = Vec::with_capacity(10); |
1a4d82fc JJ |
343 | /// |
344 | /// // The vector contains no items, even though it has capacity for more | |
345 | /// assert_eq!(vec.len(), 0); | |
346 | /// | |
347 | /// // These are all done without reallocating... | |
85aaf69f | 348 | /// for i in 0..10 { |
1a4d82fc JJ |
349 | /// vec.push(i); |
350 | /// } | |
351 | /// | |
352 | /// // ...but this may make the vector reallocate | |
353 | /// vec.push(11); | |
354 | /// ``` | |
355 | #[inline] | |
85aaf69f SL |
356 | #[stable(feature = "rust1", since = "1.0.0")] |
357 | pub fn with_capacity(capacity: usize) -> Vec<T> { | |
92a42be0 SL |
358 | Vec { |
359 | buf: RawVec::with_capacity(capacity), | |
360 | len: 0, | |
361 | } | |
1a4d82fc JJ |
362 | } |
363 | ||
364 | /// Creates a `Vec<T>` directly from the raw components of another vector. | |
365 | /// | |
b039eaaf | 366 | /// # Safety |
c1a9b12d SL |
367 | /// |
368 | /// This is highly unsafe, due to the number of invariants that aren't | |
369 | /// checked: | |
370 | /// | |
c30ab7b3 | 371 | /// * `ptr` needs to have been previously allocated via [`String`]/`Vec<T>` |
c1a9b12d | 372 | /// (at least, it's highly likely to be incorrect if it wasn't). |
5bcae85e | 373 | /// * `length` needs to be less than or equal to `capacity`. |
c1a9b12d SL |
374 | /// * `capacity` needs to be the capacity that the pointer was allocated with. |
375 | /// | |
376 | /// Violating these may cause problems like corrupting the allocator's | |
32a655c1 SL |
377 | /// internal datastructures. For example it is **not** safe |
378 | /// to build a `Vec<u8>` from a pointer to a C `char` array and a `size_t`. | |
1a4d82fc | 379 | /// |
5bcae85e SL |
380 | /// The ownership of `ptr` is effectively transferred to the |
381 | /// `Vec<T>` which may then deallocate, reallocate or change the | |
382 | /// contents of memory pointed to by the pointer at will. Ensure | |
383 | /// that nothing else uses the pointer after calling this | |
384 | /// function. | |
385 | /// | |
c30ab7b3 SL |
386 | /// [`String`]: ../../std/string/struct.String.html |
387 | /// | |
1a4d82fc JJ |
388 | /// # Examples |
389 | /// | |
390 | /// ``` | |
391 | /// use std::ptr; | |
392 | /// use std::mem; | |
393 | /// | |
394 | /// fn main() { | |
85aaf69f | 395 | /// let mut v = vec![1, 2, 3]; |
1a4d82fc JJ |
396 | /// |
397 | /// // Pull out the various important pieces of information about `v` | |
398 | /// let p = v.as_mut_ptr(); | |
399 | /// let len = v.len(); | |
400 | /// let cap = v.capacity(); | |
401 | /// | |
402 | /// unsafe { | |
403 | /// // Cast `v` into the void: no destructor run, so we are in | |
404 | /// // complete control of the allocation to which `p` points. | |
405 | /// mem::forget(v); | |
406 | /// | |
407 | /// // Overwrite memory with 4, 5, 6 | |
85aaf69f | 408 | /// for i in 0..len as isize { |
1a4d82fc JJ |
409 | /// ptr::write(p.offset(i), 4 + i); |
410 | /// } | |
411 | /// | |
412 | /// // Put everything back together into a Vec | |
413 | /// let rebuilt = Vec::from_raw_parts(p, len, cap); | |
c34b1796 | 414 | /// assert_eq!(rebuilt, [4, 5, 6]); |
1a4d82fc JJ |
415 | /// } |
416 | /// } | |
417 | /// ``` | |
85aaf69f | 418 | #[stable(feature = "rust1", since = "1.0.0")] |
92a42be0 | 419 | pub unsafe fn from_raw_parts(ptr: *mut T, length: usize, capacity: usize) -> Vec<T> { |
85aaf69f | 420 | Vec { |
c1a9b12d | 421 | buf: RawVec::from_raw_parts(ptr, capacity), |
85aaf69f | 422 | len: length, |
85aaf69f | 423 | } |
1a4d82fc JJ |
424 | } |
425 | ||
1a4d82fc JJ |
426 | /// Returns the number of elements the vector can hold without |
427 | /// reallocating. | |
428 | /// | |
429 | /// # Examples | |
430 | /// | |
431 | /// ``` | |
85aaf69f | 432 | /// let vec: Vec<i32> = Vec::with_capacity(10); |
1a4d82fc JJ |
433 | /// assert_eq!(vec.capacity(), 10); |
434 | /// ``` | |
435 | #[inline] | |
85aaf69f SL |
436 | #[stable(feature = "rust1", since = "1.0.0")] |
437 | pub fn capacity(&self) -> usize { | |
c1a9b12d | 438 | self.buf.cap() |
1a4d82fc JJ |
439 | } |
440 | ||
c34b1796 AL |
441 | /// Reserves capacity for at least `additional` more elements to be inserted |
442 | /// in the given `Vec<T>`. The collection may reserve more space to avoid | |
8bb4bdeb XL |
443 | /// frequent reallocations. After calling `reserve`, capacity will be |
444 | /// greater than or equal to `self.len() + additional`. Does nothing if | |
445 | /// capacity is already sufficient. | |
1a4d82fc JJ |
446 | /// |
447 | /// # Panics | |
448 | /// | |
85aaf69f | 449 | /// Panics if the new capacity overflows `usize`. |
1a4d82fc JJ |
450 | /// |
451 | /// # Examples | |
452 | /// | |
453 | /// ``` | |
85aaf69f | 454 | /// let mut vec = vec![1]; |
1a4d82fc JJ |
455 | /// vec.reserve(10); |
456 | /// assert!(vec.capacity() >= 11); | |
457 | /// ``` | |
85aaf69f SL |
458 | #[stable(feature = "rust1", since = "1.0.0")] |
459 | pub fn reserve(&mut self, additional: usize) { | |
c1a9b12d | 460 | self.buf.reserve(self.len, additional); |
1a4d82fc JJ |
461 | } |
462 | ||
463 | /// Reserves the minimum capacity for exactly `additional` more elements to | |
8bb4bdeb XL |
464 | /// be inserted in the given `Vec<T>`. After calling `reserve_exact`, |
465 | /// capacity will be greater than or equal to `self.len() + additional`. | |
466 | /// Does nothing if the capacity is already sufficient. | |
1a4d82fc JJ |
467 | /// |
468 | /// Note that the allocator may give the collection more space than it | |
469 | /// requests. Therefore capacity can not be relied upon to be precisely | |
470 | /// minimal. Prefer `reserve` if future insertions are expected. | |
471 | /// | |
472 | /// # Panics | |
473 | /// | |
85aaf69f | 474 | /// Panics if the new capacity overflows `usize`. |
1a4d82fc JJ |
475 | /// |
476 | /// # Examples | |
477 | /// | |
478 | /// ``` | |
85aaf69f | 479 | /// let mut vec = vec![1]; |
1a4d82fc JJ |
480 | /// vec.reserve_exact(10); |
481 | /// assert!(vec.capacity() >= 11); | |
482 | /// ``` | |
85aaf69f SL |
483 | #[stable(feature = "rust1", since = "1.0.0")] |
484 | pub fn reserve_exact(&mut self, additional: usize) { | |
c1a9b12d | 485 | self.buf.reserve_exact(self.len, additional); |
1a4d82fc JJ |
486 | } |
487 | ||
488 | /// Shrinks the capacity of the vector as much as possible. | |
489 | /// | |
490 | /// It will drop down as close as possible to the length but the allocator | |
491 | /// may still inform the vector that there is space for a few more elements. | |
492 | /// | |
493 | /// # Examples | |
494 | /// | |
495 | /// ``` | |
85aaf69f | 496 | /// let mut vec = Vec::with_capacity(10); |
62682a34 | 497 | /// vec.extend([1, 2, 3].iter().cloned()); |
1a4d82fc JJ |
498 | /// assert_eq!(vec.capacity(), 10); |
499 | /// vec.shrink_to_fit(); | |
500 | /// assert!(vec.capacity() >= 3); | |
501 | /// ``` | |
85aaf69f | 502 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 503 | pub fn shrink_to_fit(&mut self) { |
c1a9b12d | 504 | self.buf.shrink_to_fit(self.len); |
1a4d82fc JJ |
505 | } |
506 | ||
c30ab7b3 | 507 | /// Converts the vector into [`Box<[T]>`][owned slice]. |
1a4d82fc JJ |
508 | /// |
509 | /// Note that this will drop any excess capacity. Calling this and | |
cc61c64b XL |
510 | /// converting back to a vector with [`into_vec`] is equivalent to calling |
511 | /// [`shrink_to_fit`]. | |
c30ab7b3 SL |
512 | /// |
513 | /// [owned slice]: ../../std/boxed/struct.Box.html | |
cc61c64b XL |
514 | /// [`into_vec`]: ../../std/primitive.slice.html#method.into_vec |
515 | /// [`shrink_to_fit`]: #method.shrink_to_fit | |
5bcae85e SL |
516 | /// |
517 | /// # Examples | |
518 | /// | |
519 | /// ``` | |
520 | /// let v = vec![1, 2, 3]; | |
521 | /// | |
522 | /// let slice = v.into_boxed_slice(); | |
523 | /// ``` | |
524 | /// | |
525 | /// Any excess capacity is removed: | |
526 | /// | |
527 | /// ``` | |
528 | /// let mut vec = Vec::with_capacity(10); | |
529 | /// vec.extend([1, 2, 3].iter().cloned()); | |
530 | /// | |
531 | /// assert_eq!(vec.capacity(), 10); | |
532 | /// let slice = vec.into_boxed_slice(); | |
533 | /// assert_eq!(slice.into_vec().capacity(), 3); | |
534 | /// ``` | |
c34b1796 | 535 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 536 | pub fn into_boxed_slice(mut self) -> Box<[T]> { |
1a4d82fc | 537 | unsafe { |
c1a9b12d SL |
538 | self.shrink_to_fit(); |
539 | let buf = ptr::read(&self.buf); | |
1a4d82fc | 540 | mem::forget(self); |
c1a9b12d | 541 | buf.into_box() |
1a4d82fc JJ |
542 | } |
543 | } | |
544 | ||
5bcae85e SL |
545 | /// Shortens the vector, keeping the first `len` elements and dropping |
546 | /// the rest. | |
1a4d82fc JJ |
547 | /// |
548 | /// If `len` is greater than the vector's current length, this has no | |
549 | /// effect. | |
550 | /// | |
5bcae85e SL |
551 | /// The [`drain`] method can emulate `truncate`, but causes the excess |
552 | /// elements to be returned instead of dropped. | |
553 | /// | |
8bb4bdeb XL |
554 | /// Note that this method has no effect on the allocated capacity |
555 | /// of the vector. | |
556 | /// | |
1a4d82fc JJ |
557 | /// # Examples |
558 | /// | |
5bcae85e SL |
559 | /// Truncating a five element vector to two elements: |
560 | /// | |
1a4d82fc | 561 | /// ``` |
92a42be0 | 562 | /// let mut vec = vec![1, 2, 3, 4, 5]; |
1a4d82fc | 563 | /// vec.truncate(2); |
c34b1796 | 564 | /// assert_eq!(vec, [1, 2]); |
1a4d82fc | 565 | /// ``` |
5bcae85e SL |
566 | /// |
567 | /// No truncation occurs when `len` is greater than the vector's current | |
568 | /// length: | |
569 | /// | |
570 | /// ``` | |
571 | /// let mut vec = vec![1, 2, 3]; | |
572 | /// vec.truncate(8); | |
573 | /// assert_eq!(vec, [1, 2, 3]); | |
574 | /// ``` | |
575 | /// | |
576 | /// Truncating when `len == 0` is equivalent to calling the [`clear`] | |
577 | /// method. | |
578 | /// | |
579 | /// ``` | |
580 | /// let mut vec = vec![1, 2, 3]; | |
581 | /// vec.truncate(0); | |
582 | /// assert_eq!(vec, []); | |
583 | /// ``` | |
584 | /// | |
585 | /// [`clear`]: #method.clear | |
586 | /// [`drain`]: #method.drain | |
85aaf69f SL |
587 | #[stable(feature = "rust1", since = "1.0.0")] |
588 | pub fn truncate(&mut self, len: usize) { | |
1a4d82fc JJ |
589 | unsafe { |
590 | // drop any extra elements | |
591 | while len < self.len { | |
54a0048b SL |
592 | // decrement len before the drop_in_place(), so a panic on Drop |
593 | // doesn't re-drop the just-failed value. | |
1a4d82fc | 594 | self.len -= 1; |
54a0048b SL |
595 | let len = self.len; |
596 | ptr::drop_in_place(self.get_unchecked_mut(len)); | |
1a4d82fc JJ |
597 | } |
598 | } | |
599 | } | |
600 | ||
9346a6ac | 601 | /// Extracts a slice containing the entire vector. |
62682a34 SL |
602 | /// |
603 | /// Equivalent to `&s[..]`. | |
5bcae85e SL |
604 | /// |
605 | /// # Examples | |
606 | /// | |
607 | /// ``` | |
608 | /// use std::io::{self, Write}; | |
609 | /// let buffer = vec![1, 2, 3, 5, 8]; | |
610 | /// io::sink().write(buffer.as_slice()).unwrap(); | |
611 | /// ``` | |
1a4d82fc | 612 | #[inline] |
9cc50fc6 | 613 | #[stable(feature = "vec_as_slice", since = "1.7.0")] |
c34b1796 AL |
614 | pub fn as_slice(&self) -> &[T] { |
615 | self | |
616 | } | |
617 | ||
62682a34 SL |
618 | /// Extracts a mutable slice of the entire vector. |
619 | /// | |
620 | /// Equivalent to `&mut s[..]`. | |
5bcae85e SL |
621 | /// |
622 | /// # Examples | |
623 | /// | |
624 | /// ``` | |
625 | /// use std::io::{self, Read}; | |
626 | /// let mut buffer = vec![0; 3]; | |
627 | /// io::repeat(0b101).read_exact(buffer.as_mut_slice()).unwrap(); | |
628 | /// ``` | |
c34b1796 | 629 | #[inline] |
9cc50fc6 | 630 | #[stable(feature = "vec_as_slice", since = "1.7.0")] |
85aaf69f | 631 | pub fn as_mut_slice(&mut self) -> &mut [T] { |
5bcae85e | 632 | self |
1a4d82fc JJ |
633 | } |
634 | ||
1a4d82fc JJ |
635 | /// Sets the length of a vector. |
636 | /// | |
637 | /// This will explicitly set the size of the vector, without actually | |
638 | /// modifying its buffers, so it is up to the caller to ensure that the | |
639 | /// vector is actually the specified size. | |
640 | /// | |
641 | /// # Examples | |
642 | /// | |
643 | /// ``` | |
5bcae85e SL |
644 | /// use std::ptr; |
645 | /// | |
646 | /// let mut vec = vec!['r', 'u', 's', 't']; | |
647 | /// | |
648 | /// unsafe { | |
649 | /// ptr::drop_in_place(&mut vec[3]); | |
650 | /// vec.set_len(3); | |
651 | /// } | |
652 | /// assert_eq!(vec, ['r', 'u', 's']); | |
653 | /// ``` | |
654 | /// | |
655 | /// In this example, there is a memory leak since the memory locations | |
656 | /// owned by the inner vectors were not freed prior to the `set_len` call: | |
657 | /// | |
658 | /// ``` | |
659 | /// let mut vec = vec![vec![1, 0, 0], | |
660 | /// vec![0, 1, 0], | |
661 | /// vec![0, 0, 1]]; | |
1a4d82fc | 662 | /// unsafe { |
5bcae85e SL |
663 | /// vec.set_len(0); |
664 | /// } | |
665 | /// ``` | |
666 | /// | |
667 | /// In this example, the vector gets expanded from zero to four items | |
668 | /// without any memory allocations occurring, resulting in vector | |
669 | /// values of unallocated memory: | |
670 | /// | |
671 | /// ``` | |
672 | /// let mut vec: Vec<char> = Vec::new(); | |
673 | /// | |
674 | /// unsafe { | |
675 | /// vec.set_len(4); | |
1a4d82fc JJ |
676 | /// } |
677 | /// ``` | |
678 | #[inline] | |
85aaf69f SL |
679 | #[stable(feature = "rust1", since = "1.0.0")] |
680 | pub unsafe fn set_len(&mut self, len: usize) { | |
1a4d82fc JJ |
681 | self.len = len; |
682 | } | |
683 | ||
cc61c64b XL |
684 | /// Removes an element from the vector and returns it. |
685 | /// | |
686 | /// The removed element is replaced by the last element of the vector. | |
1a4d82fc JJ |
687 | /// |
688 | /// This does not preserve ordering, but is O(1). | |
689 | /// | |
690 | /// # Panics | |
691 | /// | |
692 | /// Panics if `index` is out of bounds. | |
693 | /// | |
694 | /// # Examples | |
695 | /// | |
696 | /// ``` | |
697 | /// let mut v = vec!["foo", "bar", "baz", "qux"]; | |
698 | /// | |
699 | /// assert_eq!(v.swap_remove(1), "bar"); | |
c34b1796 | 700 | /// assert_eq!(v, ["foo", "qux", "baz"]); |
1a4d82fc JJ |
701 | /// |
702 | /// assert_eq!(v.swap_remove(0), "foo"); | |
c34b1796 | 703 | /// assert_eq!(v, ["baz", "qux"]); |
1a4d82fc JJ |
704 | /// ``` |
705 | #[inline] | |
85aaf69f SL |
706 | #[stable(feature = "rust1", since = "1.0.0")] |
707 | pub fn swap_remove(&mut self, index: usize) -> T { | |
1a4d82fc JJ |
708 | let length = self.len(); |
709 | self.swap(index, length - 1); | |
710 | self.pop().unwrap() | |
711 | } | |
712 | ||
713 | /// Inserts an element at position `index` within the vector, shifting all | |
7453a54e | 714 | /// elements after it to the right. |
1a4d82fc JJ |
715 | /// |
716 | /// # Panics | |
717 | /// | |
c30ab7b3 | 718 | /// Panics if `index` is out of bounds. |
1a4d82fc JJ |
719 | /// |
720 | /// # Examples | |
721 | /// | |
722 | /// ``` | |
85aaf69f | 723 | /// let mut vec = vec![1, 2, 3]; |
1a4d82fc | 724 | /// vec.insert(1, 4); |
c34b1796 | 725 | /// assert_eq!(vec, [1, 4, 2, 3]); |
1a4d82fc | 726 | /// vec.insert(4, 5); |
c34b1796 | 727 | /// assert_eq!(vec, [1, 4, 2, 3, 5]); |
1a4d82fc | 728 | /// ``` |
85aaf69f SL |
729 | #[stable(feature = "rust1", since = "1.0.0")] |
730 | pub fn insert(&mut self, index: usize, element: T) { | |
1a4d82fc JJ |
731 | let len = self.len(); |
732 | assert!(index <= len); | |
c1a9b12d | 733 | |
1a4d82fc | 734 | // space for the new element |
92a42be0 SL |
735 | if len == self.buf.cap() { |
736 | self.buf.double(); | |
737 | } | |
1a4d82fc | 738 | |
92a42be0 SL |
739 | unsafe { |
740 | // infallible | |
1a4d82fc JJ |
741 | // The spot to put the new value |
742 | { | |
85aaf69f | 743 | let p = self.as_mut_ptr().offset(index as isize); |
1a4d82fc JJ |
744 | // Shift everything over to make space. (Duplicating the |
745 | // `index`th element into two consecutive places.) | |
c1a9b12d | 746 | ptr::copy(p, p.offset(1), len - index); |
1a4d82fc JJ |
747 | // Write it in, overwriting the first copy of the `index`th |
748 | // element. | |
c1a9b12d | 749 | ptr::write(p, element); |
1a4d82fc JJ |
750 | } |
751 | self.set_len(len + 1); | |
752 | } | |
753 | } | |
754 | ||
755 | /// Removes and returns the element at position `index` within the vector, | |
7453a54e | 756 | /// shifting all elements after it to the left. |
1a4d82fc JJ |
757 | /// |
758 | /// # Panics | |
759 | /// | |
bd371182 | 760 | /// Panics if `index` is out of bounds. |
1a4d82fc JJ |
761 | /// |
762 | /// # Examples | |
763 | /// | |
764 | /// ``` | |
85aaf69f | 765 | /// let mut v = vec![1, 2, 3]; |
1a4d82fc | 766 | /// assert_eq!(v.remove(1), 2); |
c34b1796 | 767 | /// assert_eq!(v, [1, 3]); |
1a4d82fc | 768 | /// ``` |
85aaf69f SL |
769 | #[stable(feature = "rust1", since = "1.0.0")] |
770 | pub fn remove(&mut self, index: usize) -> T { | |
1a4d82fc JJ |
771 | let len = self.len(); |
772 | assert!(index < len); | |
92a42be0 SL |
773 | unsafe { |
774 | // infallible | |
1a4d82fc JJ |
775 | let ret; |
776 | { | |
777 | // the place we are taking from. | |
85aaf69f | 778 | let ptr = self.as_mut_ptr().offset(index as isize); |
1a4d82fc JJ |
779 | // copy it out, unsafely having a copy of the value on |
780 | // the stack and in the vector at the same time. | |
85aaf69f | 781 | ret = ptr::read(ptr); |
1a4d82fc JJ |
782 | |
783 | // Shift everything down to fill in that spot. | |
c1a9b12d | 784 | ptr::copy(ptr.offset(1), ptr, len - index - 1); |
1a4d82fc JJ |
785 | } |
786 | self.set_len(len - 1); | |
787 | ret | |
788 | } | |
789 | } | |
790 | ||
791 | /// Retains only the elements specified by the predicate. | |
792 | /// | |
c30ab7b3 | 793 | /// In other words, remove all elements `e` such that `f(&e)` returns `false`. |
1a4d82fc JJ |
794 | /// This method operates in place and preserves the order of the retained |
795 | /// elements. | |
796 | /// | |
797 | /// # Examples | |
798 | /// | |
799 | /// ``` | |
85aaf69f | 800 | /// let mut vec = vec![1, 2, 3, 4]; |
1a4d82fc | 801 | /// vec.retain(|&x| x%2 == 0); |
c34b1796 | 802 | /// assert_eq!(vec, [2, 4]); |
1a4d82fc | 803 | /// ``` |
85aaf69f | 804 | #[stable(feature = "rust1", since = "1.0.0")] |
92a42be0 SL |
805 | pub fn retain<F>(&mut self, mut f: F) |
806 | where F: FnMut(&T) -> bool | |
807 | { | |
1a4d82fc | 808 | let len = self.len(); |
85aaf69f | 809 | let mut del = 0; |
1a4d82fc | 810 | { |
85aaf69f | 811 | let v = &mut **self; |
1a4d82fc | 812 | |
85aaf69f | 813 | for i in 0..len { |
1a4d82fc JJ |
814 | if !f(&v[i]) { |
815 | del += 1; | |
816 | } else if del > 0 { | |
92a42be0 | 817 | v.swap(i - del, i); |
1a4d82fc JJ |
818 | } |
819 | } | |
820 | } | |
821 | if del > 0 { | |
822 | self.truncate(len - del); | |
823 | } | |
824 | } | |
825 | ||
c30ab7b3 SL |
826 | /// Removes consecutive elements in the vector that resolve to the same key. |
827 | /// | |
828 | /// If the vector is sorted, this removes all duplicates. | |
829 | /// | |
830 | /// # Examples | |
831 | /// | |
832 | /// ``` | |
c30ab7b3 SL |
833 | /// let mut vec = vec![10, 20, 21, 30, 20]; |
834 | /// | |
835 | /// vec.dedup_by_key(|i| *i / 10); | |
836 | /// | |
837 | /// assert_eq!(vec, [10, 20, 30, 20]); | |
838 | /// ``` | |
32a655c1 | 839 | #[stable(feature = "dedup_by", since = "1.16.0")] |
c30ab7b3 SL |
840 | #[inline] |
841 | pub fn dedup_by_key<F, K>(&mut self, mut key: F) where F: FnMut(&mut T) -> K, K: PartialEq { | |
842 | self.dedup_by(|a, b| key(a) == key(b)) | |
843 | } | |
844 | ||
cc61c64b XL |
845 | /// Removes consecutive elements in the vector according to a predicate. |
846 | /// | |
847 | /// The `same_bucket` function is passed references to two elements from the vector, and | |
848 | /// returns `true` if the elements compare equal, or `false` if they do not. Only the first | |
849 | /// of adjacent equal items is kept. | |
c30ab7b3 SL |
850 | /// |
851 | /// If the vector is sorted, this removes all duplicates. | |
852 | /// | |
853 | /// # Examples | |
854 | /// | |
855 | /// ``` | |
c30ab7b3 SL |
856 | /// use std::ascii::AsciiExt; |
857 | /// | |
858 | /// let mut vec = vec!["foo", "bar", "Bar", "baz", "bar"]; | |
859 | /// | |
860 | /// vec.dedup_by(|a, b| a.eq_ignore_ascii_case(b)); | |
861 | /// | |
862 | /// assert_eq!(vec, ["foo", "bar", "baz", "bar"]); | |
863 | /// ``` | |
32a655c1 | 864 | #[stable(feature = "dedup_by", since = "1.16.0")] |
c30ab7b3 SL |
865 | pub fn dedup_by<F>(&mut self, mut same_bucket: F) where F: FnMut(&mut T, &mut T) -> bool { |
866 | unsafe { | |
867 | // Although we have a mutable reference to `self`, we cannot make | |
868 | // *arbitrary* changes. The `same_bucket` calls could panic, so we | |
869 | // must ensure that the vector is in a valid state at all time. | |
870 | // | |
871 | // The way that we handle this is by using swaps; we iterate | |
872 | // over all the elements, swapping as we go so that at the end | |
873 | // the elements we wish to keep are in the front, and those we | |
874 | // wish to reject are at the back. We can then truncate the | |
875 | // vector. This operation is still O(n). | |
876 | // | |
877 | // Example: We start in this state, where `r` represents "next | |
878 | // read" and `w` represents "next_write`. | |
879 | // | |
880 | // r | |
881 | // +---+---+---+---+---+---+ | |
882 | // | 0 | 1 | 1 | 2 | 3 | 3 | | |
883 | // +---+---+---+---+---+---+ | |
884 | // w | |
885 | // | |
886 | // Comparing self[r] against self[w-1], this is not a duplicate, so | |
887 | // we swap self[r] and self[w] (no effect as r==w) and then increment both | |
888 | // r and w, leaving us with: | |
889 | // | |
890 | // r | |
891 | // +---+---+---+---+---+---+ | |
892 | // | 0 | 1 | 1 | 2 | 3 | 3 | | |
893 | // +---+---+---+---+---+---+ | |
894 | // w | |
895 | // | |
896 | // Comparing self[r] against self[w-1], this value is a duplicate, | |
897 | // so we increment `r` but leave everything else unchanged: | |
898 | // | |
899 | // r | |
900 | // +---+---+---+---+---+---+ | |
901 | // | 0 | 1 | 1 | 2 | 3 | 3 | | |
902 | // +---+---+---+---+---+---+ | |
903 | // w | |
904 | // | |
905 | // Comparing self[r] against self[w-1], this is not a duplicate, | |
906 | // so swap self[r] and self[w] and advance r and w: | |
907 | // | |
908 | // r | |
909 | // +---+---+---+---+---+---+ | |
910 | // | 0 | 1 | 2 | 1 | 3 | 3 | | |
911 | // +---+---+---+---+---+---+ | |
912 | // w | |
913 | // | |
914 | // Not a duplicate, repeat: | |
915 | // | |
916 | // r | |
917 | // +---+---+---+---+---+---+ | |
918 | // | 0 | 1 | 2 | 3 | 1 | 3 | | |
919 | // +---+---+---+---+---+---+ | |
920 | // w | |
921 | // | |
922 | // Duplicate, advance r. End of vec. Truncate to w. | |
923 | ||
924 | let ln = self.len(); | |
925 | if ln <= 1 { | |
926 | return; | |
927 | } | |
928 | ||
929 | // Avoid bounds checks by using raw pointers. | |
930 | let p = self.as_mut_ptr(); | |
931 | let mut r: usize = 1; | |
932 | let mut w: usize = 1; | |
933 | ||
934 | while r < ln { | |
935 | let p_r = p.offset(r as isize); | |
936 | let p_wm1 = p.offset((w - 1) as isize); | |
937 | if !same_bucket(&mut *p_r, &mut *p_wm1) { | |
938 | if r != w { | |
939 | let p_w = p_wm1.offset(1); | |
940 | mem::swap(&mut *p_r, &mut *p_w); | |
941 | } | |
942 | w += 1; | |
943 | } | |
944 | r += 1; | |
945 | } | |
946 | ||
947 | self.truncate(w); | |
948 | } | |
949 | } | |
950 | ||
1a4d82fc JJ |
951 | /// Appends an element to the back of a collection. |
952 | /// | |
953 | /// # Panics | |
954 | /// | |
85aaf69f | 955 | /// Panics if the number of elements in the vector overflows a `usize`. |
1a4d82fc JJ |
956 | /// |
957 | /// # Examples | |
958 | /// | |
c34b1796 | 959 | /// ``` |
c1a9b12d | 960 | /// let mut vec = vec![1, 2]; |
1a4d82fc | 961 | /// vec.push(3); |
c34b1796 | 962 | /// assert_eq!(vec, [1, 2, 3]); |
1a4d82fc JJ |
963 | /// ``` |
964 | #[inline] | |
85aaf69f | 965 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 966 | pub fn push(&mut self, value: T) { |
c1a9b12d SL |
967 | // This will panic or abort if we would allocate > isize::MAX bytes |
968 | // or if the length increment would overflow for zero-sized types. | |
92a42be0 SL |
969 | if self.len == self.buf.cap() { |
970 | self.buf.double(); | |
971 | } | |
1a4d82fc | 972 | unsafe { |
c1a9b12d SL |
973 | let end = self.as_mut_ptr().offset(self.len as isize); |
974 | ptr::write(end, value); | |
1a4d82fc JJ |
975 | self.len += 1; |
976 | } | |
977 | } | |
978 | ||
cc61c64b XL |
979 | /// Returns a place for insertion at the back of the `Vec`. |
980 | /// | |
981 | /// Using this method with placement syntax is equivalent to [`push`](#method.push), | |
982 | /// but may be more efficient. | |
983 | /// | |
984 | /// # Examples | |
985 | /// | |
986 | /// ``` | |
987 | /// #![feature(collection_placement)] | |
988 | /// #![feature(placement_in_syntax)] | |
989 | /// | |
990 | /// let mut vec = vec![1, 2]; | |
991 | /// vec.place_back() <- 3; | |
992 | /// vec.place_back() <- 4; | |
993 | /// assert_eq!(&vec, &[1, 2, 3, 4]); | |
994 | /// ``` | |
995 | #[unstable(feature = "collection_placement", | |
996 | reason = "placement protocol is subject to change", | |
997 | issue = "30172")] | |
998 | pub fn place_back(&mut self) -> PlaceBack<T> { | |
999 | PlaceBack { vec: self } | |
1000 | } | |
1001 | ||
c30ab7b3 | 1002 | /// Removes the last element from a vector and returns it, or [`None`] if it |
e9174d1e | 1003 | /// is empty. |
1a4d82fc | 1004 | /// |
c30ab7b3 SL |
1005 | /// [`None`]: ../../std/option/enum.Option.html#variant.None |
1006 | /// | |
1a4d82fc JJ |
1007 | /// # Examples |
1008 | /// | |
c34b1796 | 1009 | /// ``` |
85aaf69f | 1010 | /// let mut vec = vec![1, 2, 3]; |
1a4d82fc | 1011 | /// assert_eq!(vec.pop(), Some(3)); |
c34b1796 | 1012 | /// assert_eq!(vec, [1, 2]); |
1a4d82fc JJ |
1013 | /// ``` |
1014 | #[inline] | |
85aaf69f | 1015 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
1016 | pub fn pop(&mut self) -> Option<T> { |
1017 | if self.len == 0 { | |
1018 | None | |
1019 | } else { | |
1020 | unsafe { | |
1021 | self.len -= 1; | |
1022 | Some(ptr::read(self.get_unchecked(self.len()))) | |
1023 | } | |
1024 | } | |
1025 | } | |
1026 | ||
85aaf69f SL |
1027 | /// Moves all the elements of `other` into `Self`, leaving `other` empty. |
1028 | /// | |
1029 | /// # Panics | |
1030 | /// | |
1031 | /// Panics if the number of elements in the vector overflows a `usize`. | |
1032 | /// | |
1033 | /// # Examples | |
1034 | /// | |
1035 | /// ``` | |
1036 | /// let mut vec = vec![1, 2, 3]; | |
1037 | /// let mut vec2 = vec![4, 5, 6]; | |
1038 | /// vec.append(&mut vec2); | |
c34b1796 AL |
1039 | /// assert_eq!(vec, [1, 2, 3, 4, 5, 6]); |
1040 | /// assert_eq!(vec2, []); | |
85aaf69f SL |
1041 | /// ``` |
1042 | #[inline] | |
e9174d1e | 1043 | #[stable(feature = "append", since = "1.4.0")] |
85aaf69f | 1044 | pub fn append(&mut self, other: &mut Self) { |
92a42be0 | 1045 | unsafe { |
cc61c64b | 1046 | self.append_elements(other.as_slice() as _); |
92a42be0 SL |
1047 | other.set_len(0); |
1048 | } | |
85aaf69f SL |
1049 | } |
1050 | ||
cc61c64b XL |
1051 | /// Appends elements to `Self` from other buffer. |
1052 | #[inline] | |
1053 | unsafe fn append_elements(&mut self, other: *const [T]) { | |
1054 | let count = (*other).len(); | |
1055 | self.reserve(count); | |
1056 | let len = self.len(); | |
1057 | ptr::copy_nonoverlapping(other as *const T, self.get_unchecked_mut(len), count); | |
1058 | self.len += count; | |
1059 | } | |
1060 | ||
7cac9316 | 1061 | /// Creates a draining iterator that removes the specified range in the vector |
9cc50fc6 | 1062 | /// and yields the removed items. |
d9579d0f | 1063 | /// |
32a655c1 SL |
1064 | /// Note 1: The element range is removed even if the iterator is only |
1065 | /// partially consumed or not consumed at all. | |
9cc50fc6 | 1066 | /// |
7cac9316 | 1067 | /// Note 2: It is unspecified how many elements are removed from the vector |
d9579d0f AL |
1068 | /// if the `Drain` value is leaked. |
1069 | /// | |
1070 | /// # Panics | |
1071 | /// | |
1072 | /// Panics if the starting point is greater than the end point or if | |
1073 | /// the end point is greater than the length of the vector. | |
1a4d82fc JJ |
1074 | /// |
1075 | /// # Examples | |
1076 | /// | |
1077 | /// ``` | |
d9579d0f | 1078 | /// let mut v = vec![1, 2, 3]; |
9cc50fc6 SL |
1079 | /// let u: Vec<_> = v.drain(1..).collect(); |
1080 | /// assert_eq!(v, &[1]); | |
1081 | /// assert_eq!(u, &[2, 3]); | |
1082 | /// | |
1083 | /// // A full range clears the vector | |
1084 | /// v.drain(..); | |
d9579d0f | 1085 | /// assert_eq!(v, &[]); |
1a4d82fc | 1086 | /// ``` |
92a42be0 SL |
1087 | #[stable(feature = "drain", since = "1.6.0")] |
1088 | pub fn drain<R>(&mut self, range: R) -> Drain<T> | |
1089 | where R: RangeArgument<usize> | |
1090 | { | |
d9579d0f AL |
1091 | // Memory safety |
1092 | // | |
1093 | // When the Drain is first created, it shortens the length of | |
1094 | // the source vector to make sure no uninitalized or moved-from elements | |
1095 | // are accessible at all if the Drain's destructor never gets to run. | |
1096 | // | |
1097 | // Drain will ptr::read out the values to remove. | |
1098 | // When finished, remaining tail of the vec is copied back to cover | |
1099 | // the hole, and the vector length is restored to the new length. | |
1100 | // | |
1101 | let len = self.len(); | |
32a655c1 SL |
1102 | let start = match range.start() { |
1103 | Included(&n) => n, | |
1104 | Excluded(&n) => n + 1, | |
1105 | Unbounded => 0, | |
1106 | }; | |
1107 | let end = match range.end() { | |
1108 | Included(&n) => n + 1, | |
1109 | Excluded(&n) => n, | |
1110 | Unbounded => len, | |
1111 | }; | |
d9579d0f AL |
1112 | assert!(start <= end); |
1113 | assert!(end <= len); | |
1114 | ||
1a4d82fc | 1115 | unsafe { |
d9579d0f AL |
1116 | // set self.vec length's to start, to be safe in case Drain is leaked |
1117 | self.set_len(start); | |
1118 | // Use the borrow in the IterMut to indicate borrowing behavior of the | |
1119 | // whole Drain iterator (like &mut T). | |
92a42be0 SL |
1120 | let range_slice = slice::from_raw_parts_mut(self.as_mut_ptr().offset(start as isize), |
1121 | end - start); | |
1a4d82fc | 1122 | Drain { |
d9579d0f AL |
1123 | tail_start: end, |
1124 | tail_len: len - end, | |
5bcae85e SL |
1125 | iter: range_slice.iter(), |
1126 | vec: Shared::new(self as *mut _), | |
1a4d82fc JJ |
1127 | } |
1128 | } | |
1129 | } | |
1130 | ||
1131 | /// Clears the vector, removing all values. | |
1132 | /// | |
8bb4bdeb XL |
1133 | /// Note that this method has no effect on the allocated capacity |
1134 | /// of the vector. | |
1135 | /// | |
1a4d82fc JJ |
1136 | /// # Examples |
1137 | /// | |
1138 | /// ``` | |
85aaf69f | 1139 | /// let mut v = vec![1, 2, 3]; |
1a4d82fc JJ |
1140 | /// |
1141 | /// v.clear(); | |
1142 | /// | |
1143 | /// assert!(v.is_empty()); | |
1144 | /// ``` | |
1145 | #[inline] | |
85aaf69f | 1146 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
1147 | pub fn clear(&mut self) { |
1148 | self.truncate(0) | |
1149 | } | |
1150 | ||
7cac9316 XL |
1151 | /// Returns the number of elements in the vector, also referred to |
1152 | /// as its 'length'. | |
1a4d82fc JJ |
1153 | /// |
1154 | /// # Examples | |
1155 | /// | |
1156 | /// ``` | |
85aaf69f | 1157 | /// let a = vec![1, 2, 3]; |
1a4d82fc JJ |
1158 | /// assert_eq!(a.len(), 3); |
1159 | /// ``` | |
1160 | #[inline] | |
85aaf69f | 1161 | #[stable(feature = "rust1", since = "1.0.0")] |
92a42be0 SL |
1162 | pub fn len(&self) -> usize { |
1163 | self.len | |
1164 | } | |
1a4d82fc JJ |
1165 | |
1166 | /// Returns `true` if the vector contains no elements. | |
1167 | /// | |
1168 | /// # Examples | |
1169 | /// | |
1170 | /// ``` | |
1171 | /// let mut v = Vec::new(); | |
1172 | /// assert!(v.is_empty()); | |
1173 | /// | |
85aaf69f | 1174 | /// v.push(1); |
1a4d82fc JJ |
1175 | /// assert!(!v.is_empty()); |
1176 | /// ``` | |
85aaf69f | 1177 | #[stable(feature = "rust1", since = "1.0.0")] |
92a42be0 SL |
1178 | pub fn is_empty(&self) -> bool { |
1179 | self.len() == 0 | |
1180 | } | |
1a4d82fc | 1181 | |
85aaf69f SL |
1182 | /// Splits the collection into two at the given index. |
1183 | /// | |
1184 | /// Returns a newly allocated `Self`. `self` contains elements `[0, at)`, | |
1185 | /// and the returned `Self` contains elements `[at, len)`. | |
1186 | /// | |
1187 | /// Note that the capacity of `self` does not change. | |
1188 | /// | |
1189 | /// # Panics | |
1190 | /// | |
1191 | /// Panics if `at > len`. | |
1192 | /// | |
1193 | /// # Examples | |
1194 | /// | |
1195 | /// ``` | |
1196 | /// let mut vec = vec![1,2,3]; | |
1197 | /// let vec2 = vec.split_off(1); | |
c34b1796 AL |
1198 | /// assert_eq!(vec, [1]); |
1199 | /// assert_eq!(vec2, [2, 3]); | |
85aaf69f SL |
1200 | /// ``` |
1201 | #[inline] | |
e9174d1e | 1202 | #[stable(feature = "split_off", since = "1.4.0")] |
85aaf69f SL |
1203 | pub fn split_off(&mut self, at: usize) -> Self { |
1204 | assert!(at <= self.len(), "`at` out of bounds"); | |
1205 | ||
1206 | let other_len = self.len - at; | |
1207 | let mut other = Vec::with_capacity(other_len); | |
1208 | ||
1209 | // Unsafely `set_len` and copy items to `other`. | |
1210 | unsafe { | |
1211 | self.set_len(at); | |
1212 | other.set_len(other_len); | |
1213 | ||
92a42be0 SL |
1214 | ptr::copy_nonoverlapping(self.as_ptr().offset(at as isize), |
1215 | other.as_mut_ptr(), | |
1216 | other.len()); | |
85aaf69f SL |
1217 | } |
1218 | other | |
1219 | } | |
1a4d82fc JJ |
1220 | } |
1221 | ||
1222 | impl<T: Clone> Vec<T> { | |
7cac9316 | 1223 | /// Resizes the `Vec` in-place so that `len` is equal to `new_len`. |
1a4d82fc | 1224 | /// |
7cac9316 | 1225 | /// If `new_len` is greater than `len`, the `Vec` is extended by the |
92a42be0 | 1226 | /// difference, with each additional slot filled with `value`. |
7cac9316 XL |
1227 | /// If `new_len` is less than `len`, the `Vec` is simply truncated. |
1228 | /// | |
1229 | /// This method requires `Clone` to clone the passed value. If you'd | |
1230 | /// rather create a value with `Default` instead, see [`resize_default`]. | |
1a4d82fc JJ |
1231 | /// |
1232 | /// # Examples | |
1233 | /// | |
1234 | /// ``` | |
1235 | /// let mut vec = vec!["hello"]; | |
1236 | /// vec.resize(3, "world"); | |
c34b1796 | 1237 | /// assert_eq!(vec, ["hello", "world", "world"]); |
1a4d82fc | 1238 | /// |
85aaf69f | 1239 | /// let mut vec = vec![1, 2, 3, 4]; |
1a4d82fc | 1240 | /// vec.resize(2, 0); |
c34b1796 | 1241 | /// assert_eq!(vec, [1, 2]); |
1a4d82fc | 1242 | /// ``` |
7cac9316 XL |
1243 | /// |
1244 | /// [`resize_default`]: #method.resize_default | |
b039eaaf | 1245 | #[stable(feature = "vec_resize", since = "1.5.0")] |
85aaf69f | 1246 | pub fn resize(&mut self, new_len: usize, value: T) { |
1a4d82fc JJ |
1247 | let len = self.len(); |
1248 | ||
1249 | if new_len > len { | |
7cac9316 | 1250 | self.extend_with(new_len - len, ExtendElement(value)) |
1a4d82fc JJ |
1251 | } else { |
1252 | self.truncate(new_len); | |
1253 | } | |
1254 | } | |
1255 | ||
7cac9316 XL |
1256 | /// Clones and appends all elements in a slice to the `Vec`. |
1257 | /// | |
1258 | /// Iterates over the slice `other`, clones each element, and then appends | |
1259 | /// it to this `Vec`. The `other` vector is traversed in-order. | |
1260 | /// | |
1261 | /// Note that this function is same as `extend` except that it is | |
1262 | /// specialized to work with slices instead. If and when Rust gets | |
1263 | /// specialization this function will likely be deprecated (but still | |
1264 | /// available). | |
1265 | /// | |
1266 | /// # Examples | |
1267 | /// | |
1268 | /// ``` | |
1269 | /// let mut vec = vec![1]; | |
1270 | /// vec.extend_from_slice(&[2, 3, 4]); | |
1271 | /// assert_eq!(vec, [1, 2, 3, 4]); | |
1272 | /// ``` | |
1273 | #[stable(feature = "vec_extend_from_slice", since = "1.6.0")] | |
1274 | pub fn extend_from_slice(&mut self, other: &[T]) { | |
1275 | self.spec_extend(other.iter()) | |
1276 | } | |
1277 | } | |
1278 | ||
1279 | impl<T: Default> Vec<T> { | |
1280 | /// Resizes the `Vec` in-place so that `len` is equal to `new_len`. | |
1281 | /// | |
1282 | /// If `new_len` is greater than `len`, the `Vec` is extended by the | |
1283 | /// difference, with each additional slot filled with `Default::default()`. | |
1284 | /// If `new_len` is less than `len`, the `Vec` is simply truncated. | |
1285 | /// | |
1286 | /// This method uses `Default` to create new values on every push. If | |
1287 | /// you'd rather `Clone` a given value, use [`resize`]. | |
1288 | /// | |
1289 | /// | |
1290 | /// # Examples | |
1291 | /// | |
1292 | /// ``` | |
1293 | /// #![feature(vec_resize_default)] | |
1294 | /// | |
1295 | /// let mut vec = vec![1, 2, 3]; | |
1296 | /// vec.resize_default(5); | |
1297 | /// assert_eq!(vec, [1, 2, 3, 0, 0]); | |
1298 | /// | |
1299 | /// let mut vec = vec![1, 2, 3, 4]; | |
1300 | /// vec.resize_default(2); | |
1301 | /// assert_eq!(vec, [1, 2]); | |
1302 | /// ``` | |
1303 | /// | |
1304 | /// [`resize`]: #method.resize | |
1305 | #[unstable(feature = "vec_resize_default", issue = "41758")] | |
1306 | pub fn resize_default(&mut self, new_len: usize) { | |
1307 | let len = self.len(); | |
1308 | ||
1309 | if new_len > len { | |
1310 | self.extend_with(new_len - len, ExtendDefault); | |
1311 | } else { | |
1312 | self.truncate(new_len); | |
1313 | } | |
1314 | } | |
1315 | } | |
1316 | ||
1317 | // This code generalises `extend_with_{element,default}`. | |
1318 | trait ExtendWith<T> { | |
1319 | fn next(&self) -> T; | |
1320 | fn last(self) -> T; | |
1321 | } | |
1322 | ||
1323 | struct ExtendElement<T>(T); | |
1324 | impl<T: Clone> ExtendWith<T> for ExtendElement<T> { | |
1325 | fn next(&self) -> T { self.0.clone() } | |
1326 | fn last(self) -> T { self.0 } | |
1327 | } | |
1328 | ||
1329 | struct ExtendDefault; | |
1330 | impl<T: Default> ExtendWith<T> for ExtendDefault { | |
1331 | fn next(&self) -> T { Default::default() } | |
1332 | fn last(self) -> T { Default::default() } | |
1333 | } | |
1334 | impl<T> Vec<T> { | |
1335 | /// Extend the vector by `n` values, using the given generator. | |
1336 | fn extend_with<E: ExtendWith<T>>(&mut self, n: usize, value: E) { | |
c1a9b12d SL |
1337 | self.reserve(n); |
1338 | ||
1339 | unsafe { | |
9e0c209e SL |
1340 | let mut ptr = self.as_mut_ptr().offset(self.len() as isize); |
1341 | // Use SetLenOnDrop to work around bug where compiler | |
8bb4bdeb | 1342 | // may not realize the store through `ptr` through self.set_len() |
9e0c209e SL |
1343 | // don't alias. |
1344 | let mut local_len = SetLenOnDrop::new(&mut self.len); | |
1345 | ||
c1a9b12d | 1346 | // Write all elements except the last one |
9e0c209e | 1347 | for _ in 1..n { |
7cac9316 | 1348 | ptr::write(ptr, value.next()); |
c1a9b12d | 1349 | ptr = ptr.offset(1); |
7cac9316 | 1350 | // Increment the length in every step in case next() panics |
9e0c209e | 1351 | local_len.increment_len(1); |
c1a9b12d SL |
1352 | } |
1353 | ||
1354 | if n > 0 { | |
1355 | // We can write the last element directly without cloning needlessly | |
7cac9316 | 1356 | ptr::write(ptr, value.last()); |
9e0c209e | 1357 | local_len.increment_len(1); |
c1a9b12d | 1358 | } |
9e0c209e SL |
1359 | |
1360 | // len set by scope guard | |
c1a9b12d SL |
1361 | } |
1362 | } | |
1a4d82fc JJ |
1363 | } |
1364 | ||
9e0c209e SL |
1365 | // Set the length of the vec when the `SetLenOnDrop` value goes out of scope. |
1366 | // | |
1367 | // The idea is: The length field in SetLenOnDrop is a local variable | |
1368 | // that the optimizer will see does not alias with any stores through the Vec's data | |
1369 | // pointer. This is a workaround for alias analysis issue #32155 | |
1370 | struct SetLenOnDrop<'a> { | |
1371 | len: &'a mut usize, | |
1372 | local_len: usize, | |
1373 | } | |
1374 | ||
1375 | impl<'a> SetLenOnDrop<'a> { | |
1376 | #[inline] | |
1377 | fn new(len: &'a mut usize) -> Self { | |
1378 | SetLenOnDrop { local_len: *len, len: len } | |
1379 | } | |
1380 | ||
1381 | #[inline] | |
1382 | fn increment_len(&mut self, increment: usize) { | |
1383 | self.local_len += increment; | |
1384 | } | |
1385 | } | |
1386 | ||
1387 | impl<'a> Drop for SetLenOnDrop<'a> { | |
1388 | #[inline] | |
1389 | fn drop(&mut self) { | |
1390 | *self.len = self.local_len; | |
1391 | } | |
1392 | } | |
1393 | ||
1a4d82fc JJ |
1394 | impl<T: PartialEq> Vec<T> { |
1395 | /// Removes consecutive repeated elements in the vector. | |
1396 | /// | |
1397 | /// If the vector is sorted, this removes all duplicates. | |
1398 | /// | |
1399 | /// # Examples | |
1400 | /// | |
1401 | /// ``` | |
85aaf69f | 1402 | /// let mut vec = vec![1, 2, 2, 3, 2]; |
1a4d82fc JJ |
1403 | /// |
1404 | /// vec.dedup(); | |
1405 | /// | |
c34b1796 | 1406 | /// assert_eq!(vec, [1, 2, 3, 2]); |
1a4d82fc | 1407 | /// ``` |
85aaf69f | 1408 | #[stable(feature = "rust1", since = "1.0.0")] |
c30ab7b3 | 1409 | #[inline] |
1a4d82fc | 1410 | pub fn dedup(&mut self) { |
c30ab7b3 | 1411 | self.dedup_by(|a, b| a == b) |
1a4d82fc | 1412 | } |
8bb4bdeb XL |
1413 | |
1414 | /// Removes the first instance of `item` from the vector if the item exists. | |
1415 | /// | |
1416 | /// # Examples | |
1417 | /// | |
1418 | /// ``` | |
cc61c64b | 1419 | /// # #![feature(vec_remove_item)] |
8bb4bdeb XL |
1420 | /// let mut vec = vec![1, 2, 3, 1]; |
1421 | /// | |
1422 | /// vec.remove_item(&1); | |
1423 | /// | |
1424 | /// assert_eq!(vec, vec![2, 3, 1]); | |
1425 | /// ``` | |
1426 | #[unstable(feature = "vec_remove_item", reason = "recently added", issue = "40062")] | |
1427 | pub fn remove_item(&mut self, item: &T) -> Option<T> { | |
1428 | let pos = match self.iter().position(|x| *x == *item) { | |
1429 | Some(x) => x, | |
1430 | None => return None, | |
1431 | }; | |
1432 | Some(self.remove(pos)) | |
1433 | } | |
1a4d82fc JJ |
1434 | } |
1435 | ||
1436 | //////////////////////////////////////////////////////////////////////////////// | |
1437 | // Internal methods and functions | |
1438 | //////////////////////////////////////////////////////////////////////////////// | |
1439 | ||
85aaf69f SL |
1440 | #[doc(hidden)] |
1441 | #[stable(feature = "rust1", since = "1.0.0")] | |
1442 | pub fn from_elem<T: Clone>(elem: T, n: usize) -> Vec<T> { | |
cc61c64b XL |
1443 | <T as SpecFromElem>::from_elem(elem, n) |
1444 | } | |
1445 | ||
1446 | // Specialization trait used for Vec::from_elem | |
1447 | trait SpecFromElem: Sized { | |
1448 | fn from_elem(elem: Self, n: usize) -> Vec<Self>; | |
1449 | } | |
1450 | ||
1451 | impl<T: Clone> SpecFromElem for T { | |
1452 | default fn from_elem(elem: Self, n: usize) -> Vec<Self> { | |
1453 | let mut v = Vec::with_capacity(n); | |
7cac9316 | 1454 | v.extend_with(n, ExtendElement(elem)); |
cc61c64b XL |
1455 | v |
1456 | } | |
85aaf69f SL |
1457 | } |
1458 | ||
cc61c64b XL |
1459 | impl SpecFromElem for u8 { |
1460 | #[inline] | |
1461 | fn from_elem(elem: u8, n: usize) -> Vec<u8> { | |
1462 | if elem == 0 { | |
1463 | return Vec { | |
1464 | buf: RawVec::with_capacity_zeroed(n), | |
1465 | len: n, | |
1466 | } | |
1467 | } | |
1468 | unsafe { | |
1469 | let mut v = Vec::with_capacity(n); | |
1470 | ptr::write_bytes(v.as_mut_ptr(), elem, n); | |
1471 | v.set_len(n); | |
1472 | v | |
1473 | } | |
1474 | } | |
1475 | } | |
1476 | ||
1477 | macro_rules! impl_spec_from_elem { | |
1478 | ($t: ty, $is_zero: expr) => { | |
1479 | impl SpecFromElem for $t { | |
1480 | #[inline] | |
1481 | fn from_elem(elem: $t, n: usize) -> Vec<$t> { | |
1482 | if $is_zero(elem) { | |
1483 | return Vec { | |
1484 | buf: RawVec::with_capacity_zeroed(n), | |
1485 | len: n, | |
1486 | } | |
1487 | } | |
1488 | let mut v = Vec::with_capacity(n); | |
7cac9316 | 1489 | v.extend_with(n, ExtendElement(elem)); |
cc61c64b XL |
1490 | v |
1491 | } | |
1492 | } | |
1493 | }; | |
1494 | } | |
1495 | ||
1496 | impl_spec_from_elem!(i8, |x| x == 0); | |
1497 | impl_spec_from_elem!(i16, |x| x == 0); | |
1498 | impl_spec_from_elem!(i32, |x| x == 0); | |
1499 | impl_spec_from_elem!(i64, |x| x == 0); | |
1500 | impl_spec_from_elem!(i128, |x| x == 0); | |
1501 | impl_spec_from_elem!(isize, |x| x == 0); | |
1502 | ||
1503 | impl_spec_from_elem!(u16, |x| x == 0); | |
1504 | impl_spec_from_elem!(u32, |x| x == 0); | |
1505 | impl_spec_from_elem!(u64, |x| x == 0); | |
1506 | impl_spec_from_elem!(u128, |x| x == 0); | |
1507 | impl_spec_from_elem!(usize, |x| x == 0); | |
1508 | ||
1509 | impl_spec_from_elem!(f32, |x: f32| x == 0. && x.is_sign_positive()); | |
1510 | impl_spec_from_elem!(f64, |x: f64| x == 0. && x.is_sign_positive()); | |
1511 | ||
1a4d82fc JJ |
1512 | //////////////////////////////////////////////////////////////////////////////// |
1513 | // Common trait implementations for Vec | |
1514 | //////////////////////////////////////////////////////////////////////////////// | |
1515 | ||
bd371182 | 1516 | #[stable(feature = "rust1", since = "1.0.0")] |
92a42be0 | 1517 | impl<T: Clone> Clone for Vec<T> { |
c34b1796 | 1518 | #[cfg(not(test))] |
92a42be0 SL |
1519 | fn clone(&self) -> Vec<T> { |
1520 | <[T]>::to_vec(&**self) | |
1521 | } | |
c34b1796 AL |
1522 | |
1523 | // HACK(japaric): with cfg(test) the inherent `[T]::to_vec` method, which is | |
1524 | // required for this method definition, is not available. Instead use the | |
1525 | // `slice::to_vec` function which is only available with cfg(test) | |
1526 | // NB see the slice::hack module in slice.rs for more information | |
1527 | #[cfg(test)] | |
1528 | fn clone(&self) -> Vec<T> { | |
1529 | ::slice::to_vec(&**self) | |
1530 | } | |
1a4d82fc JJ |
1531 | |
1532 | fn clone_from(&mut self, other: &Vec<T>) { | |
cc61c64b | 1533 | other.as_slice().clone_into(self); |
1a4d82fc JJ |
1534 | } |
1535 | } | |
1536 | ||
85aaf69f | 1537 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f | 1538 | impl<T: Hash> Hash for Vec<T> { |
1a4d82fc | 1539 | #[inline] |
85aaf69f SL |
1540 | fn hash<H: hash::Hasher>(&self, state: &mut H) { |
1541 | Hash::hash(&**self, state) | |
1a4d82fc JJ |
1542 | } |
1543 | } | |
1544 | ||
85aaf69f SL |
1545 | #[stable(feature = "rust1", since = "1.0.0")] |
1546 | impl<T> Index<usize> for Vec<T> { | |
1a4d82fc JJ |
1547 | type Output = T; |
1548 | ||
1549 | #[inline] | |
c34b1796 | 1550 | fn index(&self, index: usize) -> &T { |
85aaf69f | 1551 | // NB built-in indexing via `&[T]` |
c34b1796 | 1552 | &(**self)[index] |
1a4d82fc JJ |
1553 | } |
1554 | } | |
1555 | ||
85aaf69f SL |
1556 | #[stable(feature = "rust1", since = "1.0.0")] |
1557 | impl<T> IndexMut<usize> for Vec<T> { | |
1a4d82fc | 1558 | #[inline] |
c34b1796 | 1559 | fn index_mut(&mut self, index: usize) -> &mut T { |
85aaf69f | 1560 | // NB built-in indexing via `&mut [T]` |
c34b1796 | 1561 | &mut (**self)[index] |
1a4d82fc JJ |
1562 | } |
1563 | } | |
1564 | ||
1565 | ||
85aaf69f SL |
1566 | #[stable(feature = "rust1", since = "1.0.0")] |
1567 | impl<T> ops::Index<ops::Range<usize>> for Vec<T> { | |
1a4d82fc | 1568 | type Output = [T]; |
c34b1796 | 1569 | |
1a4d82fc | 1570 | #[inline] |
c34b1796 | 1571 | fn index(&self, index: ops::Range<usize>) -> &[T] { |
85aaf69f | 1572 | Index::index(&**self, index) |
1a4d82fc JJ |
1573 | } |
1574 | } | |
85aaf69f SL |
1575 | #[stable(feature = "rust1", since = "1.0.0")] |
1576 | impl<T> ops::Index<ops::RangeTo<usize>> for Vec<T> { | |
1a4d82fc | 1577 | type Output = [T]; |
c34b1796 | 1578 | |
1a4d82fc | 1579 | #[inline] |
c34b1796 | 1580 | fn index(&self, index: ops::RangeTo<usize>) -> &[T] { |
85aaf69f | 1581 | Index::index(&**self, index) |
1a4d82fc JJ |
1582 | } |
1583 | } | |
85aaf69f SL |
1584 | #[stable(feature = "rust1", since = "1.0.0")] |
1585 | impl<T> ops::Index<ops::RangeFrom<usize>> for Vec<T> { | |
1a4d82fc | 1586 | type Output = [T]; |
c34b1796 | 1587 | |
1a4d82fc | 1588 | #[inline] |
c34b1796 | 1589 | fn index(&self, index: ops::RangeFrom<usize>) -> &[T] { |
85aaf69f | 1590 | Index::index(&**self, index) |
1a4d82fc JJ |
1591 | } |
1592 | } | |
85aaf69f SL |
1593 | #[stable(feature = "rust1", since = "1.0.0")] |
1594 | impl<T> ops::Index<ops::RangeFull> for Vec<T> { | |
1a4d82fc | 1595 | type Output = [T]; |
c34b1796 | 1596 | |
1a4d82fc | 1597 | #[inline] |
c34b1796 AL |
1598 | fn index(&self, _index: ops::RangeFull) -> &[T] { |
1599 | self | |
1a4d82fc JJ |
1600 | } |
1601 | } | |
54a0048b SL |
1602 | #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")] |
1603 | impl<T> ops::Index<ops::RangeInclusive<usize>> for Vec<T> { | |
1604 | type Output = [T]; | |
1605 | ||
1606 | #[inline] | |
1607 | fn index(&self, index: ops::RangeInclusive<usize>) -> &[T] { | |
1608 | Index::index(&**self, index) | |
1609 | } | |
1610 | } | |
1611 | #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")] | |
1612 | impl<T> ops::Index<ops::RangeToInclusive<usize>> for Vec<T> { | |
1613 | type Output = [T]; | |
1614 | ||
1615 | #[inline] | |
1616 | fn index(&self, index: ops::RangeToInclusive<usize>) -> &[T] { | |
1617 | Index::index(&**self, index) | |
1618 | } | |
1619 | } | |
1a4d82fc | 1620 | |
85aaf69f SL |
1621 | #[stable(feature = "rust1", since = "1.0.0")] |
1622 | impl<T> ops::IndexMut<ops::Range<usize>> for Vec<T> { | |
1a4d82fc | 1623 | #[inline] |
c34b1796 | 1624 | fn index_mut(&mut self, index: ops::Range<usize>) -> &mut [T] { |
85aaf69f | 1625 | IndexMut::index_mut(&mut **self, index) |
1a4d82fc JJ |
1626 | } |
1627 | } | |
85aaf69f SL |
1628 | #[stable(feature = "rust1", since = "1.0.0")] |
1629 | impl<T> ops::IndexMut<ops::RangeTo<usize>> for Vec<T> { | |
1a4d82fc | 1630 | #[inline] |
c34b1796 | 1631 | fn index_mut(&mut self, index: ops::RangeTo<usize>) -> &mut [T] { |
85aaf69f | 1632 | IndexMut::index_mut(&mut **self, index) |
1a4d82fc JJ |
1633 | } |
1634 | } | |
85aaf69f SL |
1635 | #[stable(feature = "rust1", since = "1.0.0")] |
1636 | impl<T> ops::IndexMut<ops::RangeFrom<usize>> for Vec<T> { | |
1a4d82fc | 1637 | #[inline] |
c34b1796 | 1638 | fn index_mut(&mut self, index: ops::RangeFrom<usize>) -> &mut [T] { |
85aaf69f | 1639 | IndexMut::index_mut(&mut **self, index) |
1a4d82fc JJ |
1640 | } |
1641 | } | |
85aaf69f SL |
1642 | #[stable(feature = "rust1", since = "1.0.0")] |
1643 | impl<T> ops::IndexMut<ops::RangeFull> for Vec<T> { | |
1a4d82fc | 1644 | #[inline] |
c34b1796 AL |
1645 | fn index_mut(&mut self, _index: ops::RangeFull) -> &mut [T] { |
1646 | self | |
1a4d82fc JJ |
1647 | } |
1648 | } | |
54a0048b SL |
1649 | #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")] |
1650 | impl<T> ops::IndexMut<ops::RangeInclusive<usize>> for Vec<T> { | |
1651 | #[inline] | |
1652 | fn index_mut(&mut self, index: ops::RangeInclusive<usize>) -> &mut [T] { | |
1653 | IndexMut::index_mut(&mut **self, index) | |
1654 | } | |
1655 | } | |
1656 | #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")] | |
1657 | impl<T> ops::IndexMut<ops::RangeToInclusive<usize>> for Vec<T> { | |
1658 | #[inline] | |
1659 | fn index_mut(&mut self, index: ops::RangeToInclusive<usize>) -> &mut [T] { | |
1660 | IndexMut::index_mut(&mut **self, index) | |
1661 | } | |
1662 | } | |
1a4d82fc | 1663 | |
85aaf69f | 1664 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
1665 | impl<T> ops::Deref for Vec<T> { |
1666 | type Target = [T]; | |
1667 | ||
c34b1796 AL |
1668 | fn deref(&self) -> &[T] { |
1669 | unsafe { | |
c1a9b12d | 1670 | let p = self.buf.ptr(); |
e9174d1e | 1671 | assume(!p.is_null()); |
c34b1796 AL |
1672 | slice::from_raw_parts(p, self.len) |
1673 | } | |
1674 | } | |
1a4d82fc JJ |
1675 | } |
1676 | ||
85aaf69f | 1677 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 1678 | impl<T> ops::DerefMut for Vec<T> { |
c34b1796 AL |
1679 | fn deref_mut(&mut self) -> &mut [T] { |
1680 | unsafe { | |
c1a9b12d | 1681 | let ptr = self.buf.ptr(); |
c34b1796 AL |
1682 | assume(!ptr.is_null()); |
1683 | slice::from_raw_parts_mut(ptr, self.len) | |
1684 | } | |
1685 | } | |
1a4d82fc JJ |
1686 | } |
1687 | ||
85aaf69f | 1688 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
1689 | impl<T> FromIterator<T> for Vec<T> { |
1690 | #[inline] | |
54a0048b | 1691 | fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Vec<T> { |
cc61c64b | 1692 | <Self as SpecExtend<T, I::IntoIter>>::from_iter(iter.into_iter()) |
1a4d82fc JJ |
1693 | } |
1694 | } | |
1695 | ||
85aaf69f SL |
1696 | #[stable(feature = "rust1", since = "1.0.0")] |
1697 | impl<T> IntoIterator for Vec<T> { | |
1698 | type Item = T; | |
1699 | type IntoIter = IntoIter<T>; | |
1700 | ||
9346a6ac AL |
1701 | /// Creates a consuming iterator, that is, one that moves each value out of |
1702 | /// the vector (from start to end). The vector cannot be used after calling | |
1703 | /// this. | |
1704 | /// | |
1705 | /// # Examples | |
1706 | /// | |
1707 | /// ``` | |
1708 | /// let v = vec!["a".to_string(), "b".to_string()]; | |
1709 | /// for s in v.into_iter() { | |
1710 | /// // s has type String, not &String | |
1711 | /// println!("{}", s); | |
1712 | /// } | |
1713 | /// ``` | |
1714 | #[inline] | |
c1a9b12d | 1715 | fn into_iter(mut self) -> IntoIter<T> { |
9346a6ac | 1716 | unsafe { |
5bcae85e SL |
1717 | let begin = self.as_mut_ptr(); |
1718 | assume(!begin.is_null()); | |
9346a6ac | 1719 | let end = if mem::size_of::<T>() == 0 { |
5bcae85e | 1720 | arith_offset(begin as *const i8, self.len() as isize) as *const T |
9346a6ac | 1721 | } else { |
5bcae85e | 1722 | begin.offset(self.len() as isize) as *const T |
9346a6ac | 1723 | }; |
5bcae85e | 1724 | let cap = self.buf.cap(); |
9346a6ac | 1725 | mem::forget(self); |
92a42be0 | 1726 | IntoIter { |
5bcae85e SL |
1727 | buf: Shared::new(begin), |
1728 | cap: cap, | |
92a42be0 SL |
1729 | ptr: begin, |
1730 | end: end, | |
1731 | } | |
9346a6ac | 1732 | } |
85aaf69f SL |
1733 | } |
1734 | } | |
1735 | ||
1736 | #[stable(feature = "rust1", since = "1.0.0")] | |
1737 | impl<'a, T> IntoIterator for &'a Vec<T> { | |
1738 | type Item = &'a T; | |
1739 | type IntoIter = slice::Iter<'a, T>; | |
1740 | ||
1741 | fn into_iter(self) -> slice::Iter<'a, T> { | |
1742 | self.iter() | |
1743 | } | |
1744 | } | |
1745 | ||
1746 | #[stable(feature = "rust1", since = "1.0.0")] | |
1747 | impl<'a, T> IntoIterator for &'a mut Vec<T> { | |
1748 | type Item = &'a mut T; | |
1749 | type IntoIter = slice::IterMut<'a, T>; | |
1750 | ||
1751 | fn into_iter(mut self) -> slice::IterMut<'a, T> { | |
1752 | self.iter_mut() | |
1753 | } | |
1754 | } | |
1755 | ||
bd371182 | 1756 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
1757 | impl<T> Extend<T> for Vec<T> { |
1758 | #[inline] | |
54a0048b | 1759 | fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I) { |
cc61c64b | 1760 | <Self as SpecExtend<T, I::IntoIter>>::spec_extend(self, iter.into_iter()) |
62682a34 SL |
1761 | } |
1762 | } | |
1763 | ||
476ff2be SL |
1764 | // Specialization trait used for Vec::from_iter and Vec::extend |
1765 | trait SpecExtend<T, I> { | |
1766 | fn from_iter(iter: I) -> Self; | |
1767 | fn spec_extend(&mut self, iter: I); | |
c30ab7b3 | 1768 | } |
c30ab7b3 | 1769 | |
476ff2be SL |
1770 | impl<T, I> SpecExtend<T, I> for Vec<T> |
1771 | where I: Iterator<Item=T>, | |
c30ab7b3 | 1772 | { |
476ff2be SL |
1773 | default fn from_iter(mut iterator: I) -> Self { |
1774 | // Unroll the first iteration, as the vector is going to be | |
1775 | // expanded on this iteration in every case when the iterable is not | |
1776 | // empty, but the loop in extend_desugared() is not going to see the | |
1777 | // vector being full in the few subsequent loop iterations. | |
1778 | // So we get better branch prediction. | |
1779 | let mut vector = match iterator.next() { | |
1780 | None => return Vec::new(), | |
1781 | Some(element) => { | |
1782 | let (lower, _) = iterator.size_hint(); | |
1783 | let mut vector = Vec::with_capacity(lower.saturating_add(1)); | |
1784 | unsafe { | |
1785 | ptr::write(vector.get_unchecked_mut(0), element); | |
1786 | vector.set_len(1); | |
1787 | } | |
1788 | vector | |
1789 | } | |
1790 | }; | |
cc61c64b | 1791 | <Vec<T> as SpecExtend<T, I>>::spec_extend(&mut vector, iterator); |
476ff2be SL |
1792 | vector |
1793 | } | |
1794 | ||
1795 | default fn spec_extend(&mut self, iter: I) { | |
1796 | self.extend_desugared(iter) | |
1797 | } | |
1798 | } | |
1799 | ||
1800 | impl<T, I> SpecExtend<T, I> for Vec<T> | |
1801 | where I: TrustedLen<Item=T>, | |
1802 | { | |
cc61c64b | 1803 | default fn from_iter(iterator: I) -> Self { |
476ff2be SL |
1804 | let mut vector = Vec::new(); |
1805 | vector.spec_extend(iterator); | |
1806 | vector | |
1807 | } | |
1808 | ||
cc61c64b | 1809 | default fn spec_extend(&mut self, iterator: I) { |
476ff2be SL |
1810 | // This is the case for a TrustedLen iterator. |
1811 | let (low, high) = iterator.size_hint(); | |
c30ab7b3 SL |
1812 | if let Some(high_value) = high { |
1813 | debug_assert_eq!(low, high_value, | |
1814 | "TrustedLen iterator's size hint is not exact: {:?}", | |
1815 | (low, high)); | |
1816 | } | |
476ff2be | 1817 | if let Some(additional) = high { |
c30ab7b3 | 1818 | self.reserve(additional); |
62682a34 | 1819 | unsafe { |
c30ab7b3 SL |
1820 | let mut ptr = self.as_mut_ptr().offset(self.len() as isize); |
1821 | let mut local_len = SetLenOnDrop::new(&mut self.len); | |
1822 | for element in iterator { | |
1823 | ptr::write(ptr, element); | |
1824 | ptr = ptr.offset(1); | |
1825 | // NB can't overflow since we would have had to alloc the address space | |
1826 | local_len.increment_len(1); | |
1827 | } | |
1828 | } | |
1829 | } else { | |
476ff2be SL |
1830 | self.extend_desugared(iterator) |
1831 | } | |
1832 | } | |
1833 | } | |
1834 | ||
cc61c64b XL |
1835 | impl<T> SpecExtend<T, IntoIter<T>> for Vec<T> { |
1836 | fn from_iter(iterator: IntoIter<T>) -> Self { | |
1837 | // A common case is passing a vector into a function which immediately | |
1838 | // re-collects into a vector. We can short circuit this if the IntoIter | |
1839 | // has not been advanced at all. | |
7cac9316 | 1840 | if iterator.buf.as_ptr() as *const _ == iterator.ptr { |
cc61c64b | 1841 | unsafe { |
7cac9316 | 1842 | let vec = Vec::from_raw_parts(iterator.buf.as_ptr(), |
cc61c64b XL |
1843 | iterator.len(), |
1844 | iterator.cap); | |
1845 | mem::forget(iterator); | |
1846 | vec | |
1847 | } | |
1848 | } else { | |
1849 | let mut vector = Vec::new(); | |
1850 | vector.spec_extend(iterator); | |
1851 | vector | |
1852 | } | |
1853 | } | |
1854 | ||
1855 | fn spec_extend(&mut self, mut iterator: IntoIter<T>) { | |
1856 | unsafe { | |
1857 | self.append_elements(iterator.as_slice() as _); | |
1858 | } | |
1859 | iterator.ptr = iterator.end; | |
1860 | } | |
1861 | } | |
1862 | ||
476ff2be SL |
1863 | impl<'a, T: 'a, I> SpecExtend<&'a T, I> for Vec<T> |
1864 | where I: Iterator<Item=&'a T>, | |
1865 | T: Clone, | |
1866 | { | |
1867 | default fn from_iter(iterator: I) -> Self { | |
1868 | SpecExtend::from_iter(iterator.cloned()) | |
1869 | } | |
1870 | ||
1871 | default fn spec_extend(&mut self, iterator: I) { | |
1872 | self.spec_extend(iterator.cloned()) | |
1873 | } | |
1874 | } | |
1875 | ||
1876 | impl<'a, T: 'a> SpecExtend<&'a T, slice::Iter<'a, T>> for Vec<T> | |
1877 | where T: Copy, | |
1878 | { | |
1879 | fn spec_extend(&mut self, iterator: slice::Iter<'a, T>) { | |
1880 | let slice = iterator.as_slice(); | |
1881 | self.reserve(slice.len()); | |
1882 | unsafe { | |
1883 | let len = self.len(); | |
1884 | self.set_len(len + slice.len()); | |
1885 | self.get_unchecked_mut(len..).copy_from_slice(slice); | |
1886 | } | |
1887 | } | |
1888 | } | |
1889 | ||
1890 | impl<T> Vec<T> { | |
1891 | fn extend_desugared<I: Iterator<Item = T>>(&mut self, mut iterator: I) { | |
1892 | // This is the case for a general iterator. | |
1893 | // | |
1894 | // This function should be the moral equivalent of: | |
1895 | // | |
1896 | // for item in iterator { | |
1897 | // self.push(item); | |
1898 | // } | |
1899 | while let Some(element) = iterator.next() { | |
1900 | let len = self.len(); | |
1901 | if len == self.capacity() { | |
1902 | let (lower, _) = iterator.size_hint(); | |
1903 | self.reserve(lower.saturating_add(1)); | |
1904 | } | |
1905 | unsafe { | |
1906 | ptr::write(self.get_unchecked_mut(len), element); | |
1907 | // NB can't overflow since we would have had to alloc the address space | |
1908 | self.set_len(len + 1); | |
62682a34 | 1909 | } |
1a4d82fc JJ |
1910 | } |
1911 | } | |
7cac9316 XL |
1912 | |
1913 | /// Creates a splicing iterator that replaces the specified range in the vector | |
1914 | /// with the given `replace_with` iterator and yields the removed items. | |
1915 | /// `replace_with` does not need to be the same length as `range`. | |
1916 | /// | |
1917 | /// Note 1: The element range is removed even if the iterator is not | |
1918 | /// consumed until the end. | |
1919 | /// | |
1920 | /// Note 2: It is unspecified how many elements are removed from the vector, | |
1921 | /// if the `Splice` value is leaked. | |
1922 | /// | |
1923 | /// Note 3: The input iterator `replace_with` is only consumed | |
1924 | /// when the `Splice` value is dropped. | |
1925 | /// | |
1926 | /// Note 4: This is optimal if: | |
1927 | /// | |
1928 | /// * The tail (elements in the vector after `range`) is empty, | |
1929 | /// * or `replace_with` yields fewer elements than `range`’s length | |
1930 | /// * or the lower bound of its `size_hint()` is exact. | |
1931 | /// | |
1932 | /// Otherwise, a temporary vector is allocated and the tail is moved twice. | |
1933 | /// | |
1934 | /// # Panics | |
1935 | /// | |
1936 | /// Panics if the starting point is greater than the end point or if | |
1937 | /// the end point is greater than the length of the vector. | |
1938 | /// | |
1939 | /// # Examples | |
1940 | /// | |
1941 | /// ``` | |
1942 | /// #![feature(splice)] | |
1943 | /// let mut v = vec![1, 2, 3]; | |
1944 | /// let new = [7, 8]; | |
1945 | /// let u: Vec<_> = v.splice(..2, new.iter().cloned()).collect(); | |
1946 | /// assert_eq!(v, &[7, 8, 3]); | |
1947 | /// assert_eq!(u, &[1, 2]); | |
1948 | /// ``` | |
1949 | #[inline] | |
1950 | #[unstable(feature = "splice", reason = "recently added", issue = "32310")] | |
1951 | pub fn splice<R, I>(&mut self, range: R, replace_with: I) -> Splice<I::IntoIter> | |
1952 | where R: RangeArgument<usize>, I: IntoIterator<Item=T> | |
1953 | { | |
1954 | Splice { | |
1955 | drain: self.drain(range), | |
1956 | replace_with: replace_with.into_iter(), | |
1957 | } | |
1958 | } | |
1959 | ||
1a4d82fc JJ |
1960 | } |
1961 | ||
62682a34 SL |
1962 | #[stable(feature = "extend_ref", since = "1.2.0")] |
1963 | impl<'a, T: 'a + Copy> Extend<&'a T> for Vec<T> { | |
92a42be0 | 1964 | fn extend<I: IntoIterator<Item = &'a T>>(&mut self, iter: I) { |
476ff2be | 1965 | self.spec_extend(iter.into_iter()) |
62682a34 SL |
1966 | } |
1967 | } | |
1968 | ||
92a42be0 SL |
1969 | macro_rules! __impl_slice_eq1 { |
1970 | ($Lhs: ty, $Rhs: ty) => { | |
1971 | __impl_slice_eq1! { $Lhs, $Rhs, Sized } | |
1972 | }; | |
1973 | ($Lhs: ty, $Rhs: ty, $Bound: ident) => { | |
1974 | #[stable(feature = "rust1", since = "1.0.0")] | |
1975 | impl<'a, 'b, A: $Bound, B> PartialEq<$Rhs> for $Lhs where A: PartialEq<B> { | |
1976 | #[inline] | |
1977 | fn eq(&self, other: &$Rhs) -> bool { self[..] == other[..] } | |
1978 | #[inline] | |
1979 | fn ne(&self, other: &$Rhs) -> bool { self[..] != other[..] } | |
1980 | } | |
1981 | } | |
1982 | } | |
1983 | ||
c34b1796 AL |
1984 | __impl_slice_eq1! { Vec<A>, Vec<B> } |
1985 | __impl_slice_eq1! { Vec<A>, &'b [B] } | |
1986 | __impl_slice_eq1! { Vec<A>, &'b mut [B] } | |
1987 | __impl_slice_eq1! { Cow<'a, [A]>, &'b [B], Clone } | |
1988 | __impl_slice_eq1! { Cow<'a, [A]>, &'b mut [B], Clone } | |
1989 | __impl_slice_eq1! { Cow<'a, [A]>, Vec<B>, Clone } | |
1990 | ||
1991 | macro_rules! array_impls { | |
1992 | ($($N: expr)+) => { | |
1993 | $( | |
1994 | // NOTE: some less important impls are omitted to reduce code bloat | |
1995 | __impl_slice_eq1! { Vec<A>, [B; $N] } | |
1996 | __impl_slice_eq1! { Vec<A>, &'b [B; $N] } | |
1997 | // __impl_slice_eq1! { Vec<A>, &'b mut [B; $N] } | |
1998 | // __impl_slice_eq1! { Cow<'a, [A]>, [B; $N], Clone } | |
1999 | // __impl_slice_eq1! { Cow<'a, [A]>, &'b [B; $N], Clone } | |
2000 | // __impl_slice_eq1! { Cow<'a, [A]>, &'b mut [B; $N], Clone } | |
2001 | )+ | |
1a4d82fc JJ |
2002 | } |
2003 | } | |
2004 | ||
c34b1796 AL |
2005 | array_impls! { |
2006 | 0 1 2 3 4 5 6 7 8 9 | |
2007 | 10 11 12 13 14 15 16 17 18 19 | |
2008 | 20 21 22 23 24 25 26 27 28 29 | |
2009 | 30 31 32 | |
1a4d82fc JJ |
2010 | } |
2011 | ||
8bb4bdeb | 2012 | /// Implements comparison of vectors, lexicographically. |
85aaf69f | 2013 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
2014 | impl<T: PartialOrd> PartialOrd for Vec<T> { |
2015 | #[inline] | |
2016 | fn partial_cmp(&self, other: &Vec<T>) -> Option<Ordering> { | |
85aaf69f | 2017 | PartialOrd::partial_cmp(&**self, &**other) |
1a4d82fc JJ |
2018 | } |
2019 | } | |
2020 | ||
85aaf69f | 2021 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
2022 | impl<T: Eq> Eq for Vec<T> {} |
2023 | ||
8bb4bdeb | 2024 | /// Implements ordering of vectors, lexicographically. |
85aaf69f | 2025 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
2026 | impl<T: Ord> Ord for Vec<T> { |
2027 | #[inline] | |
2028 | fn cmp(&self, other: &Vec<T>) -> Ordering { | |
85aaf69f | 2029 | Ord::cmp(&**self, &**other) |
1a4d82fc JJ |
2030 | } |
2031 | } | |
2032 | ||
85aaf69f | 2033 | #[stable(feature = "rust1", since = "1.0.0")] |
32a655c1 | 2034 | unsafe impl<#[may_dangle] T> Drop for Vec<T> { |
1a4d82fc | 2035 | fn drop(&mut self) { |
9e0c209e SL |
2036 | unsafe { |
2037 | // use drop for [T] | |
2038 | ptr::drop_in_place(&mut self[..]); | |
1a4d82fc | 2039 | } |
c1a9b12d | 2040 | // RawVec handles deallocation |
1a4d82fc JJ |
2041 | } |
2042 | } | |
2043 | ||
85aaf69f | 2044 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 2045 | impl<T> Default for Vec<T> { |
9e0c209e | 2046 | /// Creates an empty `Vec<T>`. |
1a4d82fc JJ |
2047 | fn default() -> Vec<T> { |
2048 | Vec::new() | |
2049 | } | |
2050 | } | |
2051 | ||
85aaf69f SL |
2052 | #[stable(feature = "rust1", since = "1.0.0")] |
2053 | impl<T: fmt::Debug> fmt::Debug for Vec<T> { | |
1a4d82fc | 2054 | fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
85aaf69f | 2055 | fmt::Debug::fmt(&**self, f) |
1a4d82fc JJ |
2056 | } |
2057 | } | |
2058 | ||
c34b1796 AL |
2059 | #[stable(feature = "rust1", since = "1.0.0")] |
2060 | impl<T> AsRef<Vec<T>> for Vec<T> { | |
2061 | fn as_ref(&self) -> &Vec<T> { | |
2062 | self | |
2063 | } | |
2064 | } | |
2065 | ||
b039eaaf SL |
2066 | #[stable(feature = "vec_as_mut", since = "1.5.0")] |
2067 | impl<T> AsMut<Vec<T>> for Vec<T> { | |
2068 | fn as_mut(&mut self) -> &mut Vec<T> { | |
2069 | self | |
2070 | } | |
2071 | } | |
2072 | ||
c34b1796 AL |
2073 | #[stable(feature = "rust1", since = "1.0.0")] |
2074 | impl<T> AsRef<[T]> for Vec<T> { | |
2075 | fn as_ref(&self) -> &[T] { | |
2076 | self | |
2077 | } | |
2078 | } | |
2079 | ||
b039eaaf SL |
2080 | #[stable(feature = "vec_as_mut", since = "1.5.0")] |
2081 | impl<T> AsMut<[T]> for Vec<T> { | |
2082 | fn as_mut(&mut self) -> &mut [T] { | |
2083 | self | |
2084 | } | |
2085 | } | |
2086 | ||
c34b1796 AL |
2087 | #[stable(feature = "rust1", since = "1.0.0")] |
2088 | impl<'a, T: Clone> From<&'a [T]> for Vec<T> { | |
2089 | #[cfg(not(test))] | |
2090 | fn from(s: &'a [T]) -> Vec<T> { | |
2091 | s.to_vec() | |
2092 | } | |
2093 | #[cfg(test)] | |
2094 | fn from(s: &'a [T]) -> Vec<T> { | |
2095 | ::slice::to_vec(s) | |
2096 | } | |
2097 | } | |
2098 | ||
7cac9316 XL |
2099 | #[stable(feature = "vec_from_mut", since = "1.19.0")] |
2100 | impl<'a, T: Clone> From<&'a mut [T]> for Vec<T> { | |
2101 | #[cfg(not(test))] | |
2102 | fn from(s: &'a mut [T]) -> Vec<T> { | |
2103 | s.to_vec() | |
2104 | } | |
2105 | #[cfg(test)] | |
2106 | fn from(s: &'a mut [T]) -> Vec<T> { | |
2107 | ::slice::to_vec(s) | |
2108 | } | |
2109 | } | |
2110 | ||
c30ab7b3 SL |
2111 | #[stable(feature = "vec_from_cow_slice", since = "1.14.0")] |
2112 | impl<'a, T> From<Cow<'a, [T]>> for Vec<T> where [T]: ToOwned<Owned=Vec<T>> { | |
2113 | fn from(s: Cow<'a, [T]>) -> Vec<T> { | |
2114 | s.into_owned() | |
2115 | } | |
2116 | } | |
2117 | ||
cc61c64b XL |
2118 | // note: test pulls in libstd, which causes errors here |
2119 | #[cfg(not(test))] | |
7cac9316 | 2120 | #[stable(feature = "vec_from_box", since = "1.18.0")] |
cc61c64b XL |
2121 | impl<T> From<Box<[T]>> for Vec<T> { |
2122 | fn from(s: Box<[T]>) -> Vec<T> { | |
2123 | s.into_vec() | |
2124 | } | |
2125 | } | |
2126 | ||
7cac9316 | 2127 | #[stable(feature = "box_from_vec", since = "1.18.0")] |
cc61c64b XL |
2128 | impl<T> Into<Box<[T]>> for Vec<T> { |
2129 | fn into(self) -> Box<[T]> { | |
2130 | self.into_boxed_slice() | |
2131 | } | |
2132 | } | |
2133 | ||
c34b1796 AL |
2134 | #[stable(feature = "rust1", since = "1.0.0")] |
2135 | impl<'a> From<&'a str> for Vec<u8> { | |
2136 | fn from(s: &'a str) -> Vec<u8> { | |
2137 | From::from(s.as_bytes()) | |
2138 | } | |
2139 | } | |
2140 | ||
1a4d82fc JJ |
2141 | //////////////////////////////////////////////////////////////////////////////// |
2142 | // Clone-on-write | |
2143 | //////////////////////////////////////////////////////////////////////////////// | |
2144 | ||
7cac9316 | 2145 | #[stable(feature = "cow_from_vec", since = "1.8.0")] |
7453a54e SL |
2146 | impl<'a, T: Clone> From<&'a [T]> for Cow<'a, [T]> { |
2147 | fn from(s: &'a [T]) -> Cow<'a, [T]> { | |
2148 | Cow::Borrowed(s) | |
2149 | } | |
2150 | } | |
2151 | ||
7cac9316 | 2152 | #[stable(feature = "cow_from_vec", since = "1.8.0")] |
7453a54e SL |
2153 | impl<'a, T: Clone> From<Vec<T>> for Cow<'a, [T]> { |
2154 | fn from(v: Vec<T>) -> Cow<'a, [T]> { | |
2155 | Cow::Owned(v) | |
2156 | } | |
2157 | } | |
2158 | ||
bd371182 | 2159 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f | 2160 | impl<'a, T> FromIterator<T> for Cow<'a, [T]> where T: Clone { |
92a42be0 | 2161 | fn from_iter<I: IntoIterator<Item = T>>(it: I) -> Cow<'a, [T]> { |
1a4d82fc JJ |
2162 | Cow::Owned(FromIterator::from_iter(it)) |
2163 | } | |
2164 | } | |
2165 | ||
1a4d82fc JJ |
2166 | //////////////////////////////////////////////////////////////////////////////// |
2167 | // Iterators | |
2168 | //////////////////////////////////////////////////////////////////////////////// | |
2169 | ||
2170 | /// An iterator that moves out of a vector. | |
5bcae85e SL |
2171 | /// |
2172 | /// This `struct` is created by the `into_iter` method on [`Vec`][`Vec`] (provided | |
2173 | /// by the [`IntoIterator`] trait). | |
2174 | /// | |
2175 | /// [`Vec`]: struct.Vec.html | |
2176 | /// [`IntoIterator`]: ../../std/iter/trait.IntoIterator.html | |
85aaf69f | 2177 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 2178 | pub struct IntoIter<T> { |
5bcae85e SL |
2179 | buf: Shared<T>, |
2180 | cap: usize, | |
1a4d82fc | 2181 | ptr: *const T, |
92a42be0 | 2182 | end: *const T, |
1a4d82fc JJ |
2183 | } |
2184 | ||
c30ab7b3 | 2185 | #[stable(feature = "vec_intoiter_debug", since = "1.13.0")] |
9e0c209e SL |
2186 | impl<T: fmt::Debug> fmt::Debug for IntoIter<T> { |
2187 | fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { | |
2188 | f.debug_tuple("IntoIter") | |
2189 | .field(&self.as_slice()) | |
2190 | .finish() | |
2191 | } | |
2192 | } | |
2193 | ||
5bcae85e SL |
2194 | impl<T> IntoIter<T> { |
2195 | /// Returns the remaining items of this iterator as a slice. | |
2196 | /// | |
2197 | /// # Examples | |
2198 | /// | |
c30ab7b3 | 2199 | /// ``` |
5bcae85e SL |
2200 | /// let vec = vec!['a', 'b', 'c']; |
2201 | /// let mut into_iter = vec.into_iter(); | |
2202 | /// assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']); | |
2203 | /// let _ = into_iter.next().unwrap(); | |
2204 | /// assert_eq!(into_iter.as_slice(), &['b', 'c']); | |
2205 | /// ``` | |
476ff2be | 2206 | #[stable(feature = "vec_into_iter_as_slice", since = "1.15.0")] |
5bcae85e SL |
2207 | pub fn as_slice(&self) -> &[T] { |
2208 | unsafe { | |
2209 | slice::from_raw_parts(self.ptr, self.len()) | |
2210 | } | |
2211 | } | |
2212 | ||
2213 | /// Returns the remaining items of this iterator as a mutable slice. | |
2214 | /// | |
2215 | /// # Examples | |
2216 | /// | |
c30ab7b3 | 2217 | /// ``` |
5bcae85e SL |
2218 | /// let vec = vec!['a', 'b', 'c']; |
2219 | /// let mut into_iter = vec.into_iter(); | |
2220 | /// assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']); | |
2221 | /// into_iter.as_mut_slice()[2] = 'z'; | |
2222 | /// assert_eq!(into_iter.next().unwrap(), 'a'); | |
2223 | /// assert_eq!(into_iter.next().unwrap(), 'b'); | |
2224 | /// assert_eq!(into_iter.next().unwrap(), 'z'); | |
2225 | /// ``` | |
476ff2be | 2226 | #[stable(feature = "vec_into_iter_as_slice", since = "1.15.0")] |
e81b0574 | 2227 | pub fn as_mut_slice(&mut self) -> &mut [T] { |
5bcae85e SL |
2228 | unsafe { |
2229 | slice::from_raw_parts_mut(self.ptr as *mut T, self.len()) | |
2230 | } | |
2231 | } | |
2232 | } | |
2233 | ||
92a42be0 SL |
2234 | #[stable(feature = "rust1", since = "1.0.0")] |
2235 | unsafe impl<T: Send> Send for IntoIter<T> {} | |
2236 | #[stable(feature = "rust1", since = "1.0.0")] | |
2237 | unsafe impl<T: Sync> Sync for IntoIter<T> {} | |
85aaf69f | 2238 | |
85aaf69f | 2239 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
2240 | impl<T> Iterator for IntoIter<T> { |
2241 | type Item = T; | |
2242 | ||
2243 | #[inline] | |
85aaf69f | 2244 | fn next(&mut self) -> Option<T> { |
1a4d82fc | 2245 | unsafe { |
5bcae85e | 2246 | if self.ptr as *const _ == self.end { |
1a4d82fc JJ |
2247 | None |
2248 | } else { | |
2249 | if mem::size_of::<T>() == 0 { | |
2250 | // purposefully don't use 'ptr.offset' because for | |
2251 | // vectors with 0-size elements this would return the | |
2252 | // same pointer. | |
5bcae85e | 2253 | self.ptr = arith_offset(self.ptr as *const i8, 1) as *mut T; |
1a4d82fc JJ |
2254 | |
2255 | // Use a non-null pointer value | |
7cac9316 XL |
2256 | // (self.ptr might be null because of wrapping) |
2257 | Some(ptr::read(1 as *mut T)) | |
1a4d82fc JJ |
2258 | } else { |
2259 | let old = self.ptr; | |
2260 | self.ptr = self.ptr.offset(1); | |
2261 | ||
2262 | Some(ptr::read(old)) | |
2263 | } | |
2264 | } | |
2265 | } | |
2266 | } | |
2267 | ||
2268 | #[inline] | |
85aaf69f | 2269 | fn size_hint(&self) -> (usize, Option<usize>) { |
cc61c64b XL |
2270 | let exact = match self.ptr.offset_to(self.end) { |
2271 | Some(x) => x as usize, | |
2272 | None => (self.end as usize).wrapping_sub(self.ptr as usize), | |
2273 | }; | |
1a4d82fc JJ |
2274 | (exact, Some(exact)) |
2275 | } | |
d9579d0f AL |
2276 | |
2277 | #[inline] | |
2278 | fn count(self) -> usize { | |
3157f602 | 2279 | self.len() |
d9579d0f | 2280 | } |
1a4d82fc JJ |
2281 | } |
2282 | ||
85aaf69f | 2283 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
2284 | impl<T> DoubleEndedIterator for IntoIter<T> { |
2285 | #[inline] | |
85aaf69f | 2286 | fn next_back(&mut self) -> Option<T> { |
1a4d82fc JJ |
2287 | unsafe { |
2288 | if self.end == self.ptr { | |
2289 | None | |
2290 | } else { | |
2291 | if mem::size_of::<T>() == 0 { | |
2292 | // See above for why 'ptr.offset' isn't used | |
5bcae85e | 2293 | self.end = arith_offset(self.end as *const i8, -1) as *mut T; |
1a4d82fc JJ |
2294 | |
2295 | // Use a non-null pointer value | |
7cac9316 XL |
2296 | // (self.end might be null because of wrapping) |
2297 | Some(ptr::read(1 as *mut T)) | |
1a4d82fc JJ |
2298 | } else { |
2299 | self.end = self.end.offset(-1); | |
2300 | ||
e9174d1e | 2301 | Some(ptr::read(self.end)) |
1a4d82fc JJ |
2302 | } |
2303 | } | |
2304 | } | |
2305 | } | |
2306 | } | |
2307 | ||
85aaf69f | 2308 | #[stable(feature = "rust1", since = "1.0.0")] |
476ff2be SL |
2309 | impl<T> ExactSizeIterator for IntoIter<T> { |
2310 | fn is_empty(&self) -> bool { | |
2311 | self.ptr == self.end | |
2312 | } | |
2313 | } | |
1a4d82fc | 2314 | |
9e0c209e SL |
2315 | #[unstable(feature = "fused", issue = "35602")] |
2316 | impl<T> FusedIterator for IntoIter<T> {} | |
2317 | ||
c30ab7b3 SL |
2318 | #[unstable(feature = "trusted_len", issue = "37572")] |
2319 | unsafe impl<T> TrustedLen for IntoIter<T> {} | |
2320 | ||
7453a54e SL |
2321 | #[stable(feature = "vec_into_iter_clone", since = "1.8.0")] |
2322 | impl<T: Clone> Clone for IntoIter<T> { | |
2323 | fn clone(&self) -> IntoIter<T> { | |
5bcae85e | 2324 | self.as_slice().to_owned().into_iter() |
7453a54e SL |
2325 | } |
2326 | } | |
2327 | ||
85aaf69f | 2328 | #[stable(feature = "rust1", since = "1.0.0")] |
32a655c1 | 2329 | unsafe impl<#[may_dangle] T> Drop for IntoIter<T> { |
1a4d82fc JJ |
2330 | fn drop(&mut self) { |
2331 | // destroy the remaining elements | |
5bcae85e | 2332 | for _x in self.by_ref() {} |
c1a9b12d SL |
2333 | |
2334 | // RawVec handles deallocation | |
7cac9316 | 2335 | let _ = unsafe { RawVec::from_raw_parts(self.buf.as_ptr(), self.cap) }; |
1a4d82fc JJ |
2336 | } |
2337 | } | |
2338 | ||
d9579d0f | 2339 | /// A draining iterator for `Vec<T>`. |
5bcae85e SL |
2340 | /// |
2341 | /// This `struct` is created by the [`drain`] method on [`Vec`]. | |
2342 | /// | |
2343 | /// [`drain`]: struct.Vec.html#method.drain | |
2344 | /// [`Vec`]: struct.Vec.html | |
92a42be0 | 2345 | #[stable(feature = "drain", since = "1.6.0")] |
d9579d0f AL |
2346 | pub struct Drain<'a, T: 'a> { |
2347 | /// Index of tail to preserve | |
2348 | tail_start: usize, | |
2349 | /// Length of tail | |
2350 | tail_len: usize, | |
2351 | /// Current remaining range to remove | |
5bcae85e SL |
2352 | iter: slice::Iter<'a, T>, |
2353 | vec: Shared<Vec<T>>, | |
1a4d82fc JJ |
2354 | } |
2355 | ||
8bb4bdeb XL |
2356 | #[stable(feature = "collection_debug", since = "1.17.0")] |
2357 | impl<'a, T: 'a + fmt::Debug> fmt::Debug for Drain<'a, T> { | |
2358 | fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { | |
2359 | f.debug_tuple("Drain") | |
2360 | .field(&self.iter.as_slice()) | |
2361 | .finish() | |
2362 | } | |
2363 | } | |
2364 | ||
92a42be0 | 2365 | #[stable(feature = "drain", since = "1.6.0")] |
c34b1796 | 2366 | unsafe impl<'a, T: Sync> Sync for Drain<'a, T> {} |
92a42be0 | 2367 | #[stable(feature = "drain", since = "1.6.0")] |
c34b1796 AL |
2368 | unsafe impl<'a, T: Send> Send for Drain<'a, T> {} |
2369 | ||
c30ab7b3 | 2370 | #[stable(feature = "drain", since = "1.6.0")] |
1a4d82fc JJ |
2371 | impl<'a, T> Iterator for Drain<'a, T> { |
2372 | type Item = T; | |
2373 | ||
2374 | #[inline] | |
2375 | fn next(&mut self) -> Option<T> { | |
92a42be0 | 2376 | self.iter.next().map(|elt| unsafe { ptr::read(elt as *const _) }) |
1a4d82fc JJ |
2377 | } |
2378 | ||
85aaf69f | 2379 | fn size_hint(&self) -> (usize, Option<usize>) { |
d9579d0f | 2380 | self.iter.size_hint() |
1a4d82fc JJ |
2381 | } |
2382 | } | |
2383 | ||
c30ab7b3 | 2384 | #[stable(feature = "drain", since = "1.6.0")] |
1a4d82fc JJ |
2385 | impl<'a, T> DoubleEndedIterator for Drain<'a, T> { |
2386 | #[inline] | |
2387 | fn next_back(&mut self) -> Option<T> { | |
92a42be0 | 2388 | self.iter.next_back().map(|elt| unsafe { ptr::read(elt as *const _) }) |
1a4d82fc JJ |
2389 | } |
2390 | } | |
2391 | ||
c30ab7b3 | 2392 | #[stable(feature = "drain", since = "1.6.0")] |
1a4d82fc JJ |
2393 | impl<'a, T> Drop for Drain<'a, T> { |
2394 | fn drop(&mut self) { | |
d9579d0f | 2395 | // exhaust self first |
92a42be0 | 2396 | while let Some(_) = self.next() {} |
1a4d82fc | 2397 | |
d9579d0f AL |
2398 | if self.tail_len > 0 { |
2399 | unsafe { | |
7cac9316 | 2400 | let source_vec = self.vec.as_mut(); |
d9579d0f AL |
2401 | // memmove back untouched tail, update to new length |
2402 | let start = source_vec.len(); | |
2403 | let tail = self.tail_start; | |
2404 | let src = source_vec.as_ptr().offset(tail as isize); | |
2405 | let dst = source_vec.as_mut_ptr().offset(start as isize); | |
2406 | ptr::copy(src, dst, self.tail_len); | |
2407 | source_vec.set_len(start + self.tail_len); | |
2408 | } | |
2409 | } | |
1a4d82fc JJ |
2410 | } |
2411 | } | |
2412 | ||
d9579d0f | 2413 | |
c30ab7b3 | 2414 | #[stable(feature = "drain", since = "1.6.0")] |
476ff2be SL |
2415 | impl<'a, T> ExactSizeIterator for Drain<'a, T> { |
2416 | fn is_empty(&self) -> bool { | |
2417 | self.iter.is_empty() | |
2418 | } | |
2419 | } | |
9e0c209e SL |
2420 | |
2421 | #[unstable(feature = "fused", issue = "35602")] | |
2422 | impl<'a, T> FusedIterator for Drain<'a, T> {} | |
32a655c1 SL |
2423 | |
2424 | /// A place for insertion at the back of a `Vec`. | |
2425 | /// | |
2426 | /// See [`Vec::place_back`](struct.Vec.html#method.place_back) for details. | |
2427 | #[must_use = "places do nothing unless written to with `<-` syntax"] | |
2428 | #[unstable(feature = "collection_placement", | |
2429 | reason = "struct name and placement protocol are subject to change", | |
2430 | issue = "30172")] | |
8bb4bdeb | 2431 | #[derive(Debug)] |
32a655c1 SL |
2432 | pub struct PlaceBack<'a, T: 'a> { |
2433 | vec: &'a mut Vec<T>, | |
2434 | } | |
2435 | ||
2436 | #[unstable(feature = "collection_placement", | |
2437 | reason = "placement protocol is subject to change", | |
2438 | issue = "30172")] | |
2439 | impl<'a, T> Placer<T> for PlaceBack<'a, T> { | |
2440 | type Place = PlaceBack<'a, T>; | |
2441 | ||
2442 | fn make_place(self) -> Self { | |
2443 | // This will panic or abort if we would allocate > isize::MAX bytes | |
2444 | // or if the length increment would overflow for zero-sized types. | |
2445 | if self.vec.len == self.vec.buf.cap() { | |
2446 | self.vec.buf.double(); | |
2447 | } | |
2448 | self | |
2449 | } | |
2450 | } | |
2451 | ||
2452 | #[unstable(feature = "collection_placement", | |
2453 | reason = "placement protocol is subject to change", | |
2454 | issue = "30172")] | |
2455 | impl<'a, T> Place<T> for PlaceBack<'a, T> { | |
2456 | fn pointer(&mut self) -> *mut T { | |
2457 | unsafe { self.vec.as_mut_ptr().offset(self.vec.len as isize) } | |
2458 | } | |
2459 | } | |
2460 | ||
2461 | #[unstable(feature = "collection_placement", | |
2462 | reason = "placement protocol is subject to change", | |
2463 | issue = "30172")] | |
2464 | impl<'a, T> InPlace<T> for PlaceBack<'a, T> { | |
2465 | type Owner = &'a mut T; | |
2466 | ||
2467 | unsafe fn finalize(mut self) -> &'a mut T { | |
2468 | let ptr = self.pointer(); | |
2469 | self.vec.len += 1; | |
2470 | &mut *ptr | |
2471 | } | |
2472 | } | |
7cac9316 XL |
2473 | |
2474 | ||
2475 | /// A splicing iterator for `Vec`. | |
2476 | /// | |
2477 | /// This struct is created by the [`splice()`] method on [`Vec`]. See its | |
2478 | /// documentation for more. | |
2479 | /// | |
2480 | /// [`splice()`]: struct.Vec.html#method.splice | |
2481 | /// [`Vec`]: struct.Vec.html | |
2482 | #[derive(Debug)] | |
2483 | #[unstable(feature = "splice", reason = "recently added", issue = "32310")] | |
2484 | pub struct Splice<'a, I: Iterator + 'a> { | |
2485 | drain: Drain<'a, I::Item>, | |
2486 | replace_with: I, | |
2487 | } | |
2488 | ||
2489 | #[unstable(feature = "splice", reason = "recently added", issue = "32310")] | |
2490 | impl<'a, I: Iterator> Iterator for Splice<'a, I> { | |
2491 | type Item = I::Item; | |
2492 | ||
2493 | fn next(&mut self) -> Option<Self::Item> { | |
2494 | self.drain.next() | |
2495 | } | |
2496 | ||
2497 | fn size_hint(&self) -> (usize, Option<usize>) { | |
2498 | self.drain.size_hint() | |
2499 | } | |
2500 | } | |
2501 | ||
2502 | #[unstable(feature = "splice", reason = "recently added", issue = "32310")] | |
2503 | impl<'a, I: Iterator> DoubleEndedIterator for Splice<'a, I> { | |
2504 | fn next_back(&mut self) -> Option<Self::Item> { | |
2505 | self.drain.next_back() | |
2506 | } | |
2507 | } | |
2508 | ||
2509 | #[unstable(feature = "splice", reason = "recently added", issue = "32310")] | |
2510 | impl<'a, I: Iterator> ExactSizeIterator for Splice<'a, I> {} | |
2511 | ||
2512 | ||
2513 | #[unstable(feature = "splice", reason = "recently added", issue = "32310")] | |
2514 | impl<'a, I: Iterator> Drop for Splice<'a, I> { | |
2515 | fn drop(&mut self) { | |
2516 | // exhaust drain first | |
2517 | while let Some(_) = self.drain.next() {} | |
2518 | ||
2519 | ||
2520 | unsafe { | |
2521 | if self.drain.tail_len == 0 { | |
2522 | self.drain.vec.as_mut().extend(self.replace_with.by_ref()); | |
2523 | return | |
2524 | } | |
2525 | ||
2526 | // First fill the range left by drain(). | |
2527 | if !self.drain.fill(&mut self.replace_with) { | |
2528 | return | |
2529 | } | |
2530 | ||
2531 | // There may be more elements. Use the lower bound as an estimate. | |
2532 | // FIXME: Is the upper bound a better guess? Or something else? | |
2533 | let (lower_bound, _upper_bound) = self.replace_with.size_hint(); | |
2534 | if lower_bound > 0 { | |
2535 | self.drain.move_tail(lower_bound); | |
2536 | if !self.drain.fill(&mut self.replace_with) { | |
2537 | return | |
2538 | } | |
2539 | } | |
2540 | ||
2541 | // Collect any remaining elements. | |
2542 | // This is a zero-length vector which does not allocate if `lower_bound` was exact. | |
2543 | let mut collected = self.replace_with.by_ref().collect::<Vec<I::Item>>().into_iter(); | |
2544 | // Now we have an exact count. | |
2545 | if collected.len() > 0 { | |
2546 | self.drain.move_tail(collected.len()); | |
2547 | let filled = self.drain.fill(&mut collected); | |
2548 | debug_assert!(filled); | |
2549 | debug_assert_eq!(collected.len(), 0); | |
2550 | } | |
2551 | } | |
2552 | // Let `Drain::drop` move the tail back if necessary and restore `vec.len`. | |
2553 | } | |
2554 | } | |
2555 | ||
2556 | /// Private helper methods for `Splice::drop` | |
2557 | impl<'a, T> Drain<'a, T> { | |
2558 | /// The range from `self.vec.len` to `self.tail_start` contains elements | |
2559 | /// that have been moved out. | |
2560 | /// Fill that range as much as possible with new elements from the `replace_with` iterator. | |
2561 | /// Return whether we filled the entire range. (`replace_with.next()` didn’t return `None`.) | |
2562 | unsafe fn fill<I: Iterator<Item=T>>(&mut self, replace_with: &mut I) -> bool { | |
2563 | let vec = self.vec.as_mut(); | |
2564 | let range_start = vec.len; | |
2565 | let range_end = self.tail_start; | |
2566 | let range_slice = slice::from_raw_parts_mut( | |
2567 | vec.as_mut_ptr().offset(range_start as isize), | |
2568 | range_end - range_start); | |
2569 | ||
2570 | for place in range_slice { | |
2571 | if let Some(new_item) = replace_with.next() { | |
2572 | ptr::write(place, new_item); | |
2573 | vec.len += 1; | |
2574 | } else { | |
2575 | return false | |
2576 | } | |
2577 | } | |
2578 | true | |
2579 | } | |
2580 | ||
2581 | /// Make room for inserting more elements before the tail. | |
2582 | unsafe fn move_tail(&mut self, extra_capacity: usize) { | |
2583 | let vec = self.vec.as_mut(); | |
2584 | let used_capacity = self.tail_start + self.tail_len; | |
2585 | vec.buf.reserve(used_capacity, extra_capacity); | |
2586 | ||
2587 | let new_tail_start = self.tail_start + extra_capacity; | |
2588 | let src = vec.as_ptr().offset(self.tail_start as isize); | |
2589 | let dst = vec.as_mut_ptr().offset(new_tail_start as isize); | |
2590 | ptr::copy(src, dst, self.tail_len); | |
2591 | self.tail_start = new_tail_start; | |
2592 | } | |
2593 | } |