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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 | 11 | //! A contiguous growable array type with heap-allocated contents, written |
041b39d2 | 12 | //! `Vec<T>`. |
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 | |
c34b1796 | 69 | use core::cmp::Ordering; |
1a4d82fc JJ |
70 | use core::fmt; |
71 | use core::hash::{self, Hash}; | |
54a0048b | 72 | use core::intrinsics::{arith_offset, assume}; |
c30ab7b3 | 73 | use core::iter::{FromIterator, FusedIterator, TrustedLen}; |
1a4d82fc | 74 | use core::mem; |
cc61c64b XL |
75 | #[cfg(not(test))] |
76 | use core::num::Float; | |
32a655c1 | 77 | use core::ops::{InPlace, Index, IndexMut, Place, Placer}; |
1a4d82fc JJ |
78 | use core::ops; |
79 | use core::ptr; | |
5bcae85e | 80 | use core::ptr::Shared; |
85aaf69f | 81 | use core::slice; |
85aaf69f | 82 | |
041b39d2 XL |
83 | use borrow::ToOwned; |
84 | use borrow::Cow; | |
85 | use boxed::Box; | |
86 | use raw_vec::RawVec; | |
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 | /// | |
041b39d2 | 159 | /// ```should_panic |
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 | 224 | /// the `Vec` may not report a [`capacity`] of 0*. `Vec` will allocate if and only |
041b39d2 | 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). |
ea8adc8c | 373 | /// * `ptr`'s `T` needs to have the same size and alignment as it was allocated with. |
5bcae85e | 374 | /// * `length` needs to be less than or equal to `capacity`. |
c1a9b12d SL |
375 | /// * `capacity` needs to be the capacity that the pointer was allocated with. |
376 | /// | |
377 | /// Violating these may cause problems like corrupting the allocator's | |
3b2f2976 | 378 | /// internal data structures. For example it is **not** safe |
32a655c1 | 379 | /// to build a `Vec<u8>` from a pointer to a C `char` array and a `size_t`. |
1a4d82fc | 380 | /// |
5bcae85e SL |
381 | /// The ownership of `ptr` is effectively transferred to the |
382 | /// `Vec<T>` which may then deallocate, reallocate or change the | |
383 | /// contents of memory pointed to by the pointer at will. Ensure | |
384 | /// that nothing else uses the pointer after calling this | |
385 | /// function. | |
386 | /// | |
c30ab7b3 SL |
387 | /// [`String`]: ../../std/string/struct.String.html |
388 | /// | |
1a4d82fc JJ |
389 | /// # Examples |
390 | /// | |
391 | /// ``` | |
392 | /// use std::ptr; | |
393 | /// use std::mem; | |
394 | /// | |
395 | /// fn main() { | |
85aaf69f | 396 | /// let mut v = vec![1, 2, 3]; |
1a4d82fc JJ |
397 | /// |
398 | /// // Pull out the various important pieces of information about `v` | |
399 | /// let p = v.as_mut_ptr(); | |
400 | /// let len = v.len(); | |
401 | /// let cap = v.capacity(); | |
402 | /// | |
403 | /// unsafe { | |
404 | /// // Cast `v` into the void: no destructor run, so we are in | |
405 | /// // complete control of the allocation to which `p` points. | |
406 | /// mem::forget(v); | |
407 | /// | |
408 | /// // Overwrite memory with 4, 5, 6 | |
85aaf69f | 409 | /// for i in 0..len as isize { |
1a4d82fc JJ |
410 | /// ptr::write(p.offset(i), 4 + i); |
411 | /// } | |
412 | /// | |
413 | /// // Put everything back together into a Vec | |
414 | /// let rebuilt = Vec::from_raw_parts(p, len, cap); | |
c34b1796 | 415 | /// assert_eq!(rebuilt, [4, 5, 6]); |
1a4d82fc JJ |
416 | /// } |
417 | /// } | |
418 | /// ``` | |
85aaf69f | 419 | #[stable(feature = "rust1", since = "1.0.0")] |
92a42be0 | 420 | pub unsafe fn from_raw_parts(ptr: *mut T, length: usize, capacity: usize) -> Vec<T> { |
85aaf69f | 421 | Vec { |
c1a9b12d | 422 | buf: RawVec::from_raw_parts(ptr, capacity), |
85aaf69f | 423 | len: length, |
85aaf69f | 424 | } |
1a4d82fc JJ |
425 | } |
426 | ||
1a4d82fc JJ |
427 | /// Returns the number of elements the vector can hold without |
428 | /// reallocating. | |
429 | /// | |
430 | /// # Examples | |
431 | /// | |
432 | /// ``` | |
85aaf69f | 433 | /// let vec: Vec<i32> = Vec::with_capacity(10); |
1a4d82fc JJ |
434 | /// assert_eq!(vec.capacity(), 10); |
435 | /// ``` | |
436 | #[inline] | |
85aaf69f SL |
437 | #[stable(feature = "rust1", since = "1.0.0")] |
438 | pub fn capacity(&self) -> usize { | |
c1a9b12d | 439 | self.buf.cap() |
1a4d82fc JJ |
440 | } |
441 | ||
c34b1796 AL |
442 | /// Reserves capacity for at least `additional` more elements to be inserted |
443 | /// in the given `Vec<T>`. The collection may reserve more space to avoid | |
8bb4bdeb XL |
444 | /// frequent reallocations. After calling `reserve`, capacity will be |
445 | /// greater than or equal to `self.len() + additional`. Does nothing if | |
446 | /// capacity is already sufficient. | |
1a4d82fc JJ |
447 | /// |
448 | /// # Panics | |
449 | /// | |
85aaf69f | 450 | /// Panics if the new capacity overflows `usize`. |
1a4d82fc JJ |
451 | /// |
452 | /// # Examples | |
453 | /// | |
454 | /// ``` | |
85aaf69f | 455 | /// let mut vec = vec![1]; |
1a4d82fc JJ |
456 | /// vec.reserve(10); |
457 | /// assert!(vec.capacity() >= 11); | |
458 | /// ``` | |
85aaf69f SL |
459 | #[stable(feature = "rust1", since = "1.0.0")] |
460 | pub fn reserve(&mut self, additional: usize) { | |
c1a9b12d | 461 | self.buf.reserve(self.len, additional); |
1a4d82fc JJ |
462 | } |
463 | ||
464 | /// Reserves the minimum capacity for exactly `additional` more elements to | |
8bb4bdeb XL |
465 | /// be inserted in the given `Vec<T>`. After calling `reserve_exact`, |
466 | /// capacity will be greater than or equal to `self.len() + additional`. | |
467 | /// Does nothing if the capacity is already sufficient. | |
1a4d82fc JJ |
468 | /// |
469 | /// Note that the allocator may give the collection more space than it | |
470 | /// requests. Therefore capacity can not be relied upon to be precisely | |
471 | /// minimal. Prefer `reserve` if future insertions are expected. | |
472 | /// | |
473 | /// # Panics | |
474 | /// | |
85aaf69f | 475 | /// Panics if the new capacity overflows `usize`. |
1a4d82fc JJ |
476 | /// |
477 | /// # Examples | |
478 | /// | |
479 | /// ``` | |
85aaf69f | 480 | /// let mut vec = vec![1]; |
1a4d82fc JJ |
481 | /// vec.reserve_exact(10); |
482 | /// assert!(vec.capacity() >= 11); | |
483 | /// ``` | |
85aaf69f SL |
484 | #[stable(feature = "rust1", since = "1.0.0")] |
485 | pub fn reserve_exact(&mut self, additional: usize) { | |
c1a9b12d | 486 | self.buf.reserve_exact(self.len, additional); |
1a4d82fc JJ |
487 | } |
488 | ||
489 | /// Shrinks the capacity of the vector as much as possible. | |
490 | /// | |
491 | /// It will drop down as close as possible to the length but the allocator | |
492 | /// may still inform the vector that there is space for a few more elements. | |
493 | /// | |
494 | /// # Examples | |
495 | /// | |
496 | /// ``` | |
85aaf69f | 497 | /// let mut vec = Vec::with_capacity(10); |
62682a34 | 498 | /// vec.extend([1, 2, 3].iter().cloned()); |
1a4d82fc JJ |
499 | /// assert_eq!(vec.capacity(), 10); |
500 | /// vec.shrink_to_fit(); | |
501 | /// assert!(vec.capacity() >= 3); | |
502 | /// ``` | |
85aaf69f | 503 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 504 | pub fn shrink_to_fit(&mut self) { |
c1a9b12d | 505 | self.buf.shrink_to_fit(self.len); |
1a4d82fc JJ |
506 | } |
507 | ||
c30ab7b3 | 508 | /// Converts the vector into [`Box<[T]>`][owned slice]. |
1a4d82fc | 509 | /// |
ea8adc8c | 510 | /// Note that this will drop any excess capacity. |
c30ab7b3 SL |
511 | /// |
512 | /// [owned slice]: ../../std/boxed/struct.Box.html | |
5bcae85e SL |
513 | /// |
514 | /// # Examples | |
515 | /// | |
516 | /// ``` | |
517 | /// let v = vec![1, 2, 3]; | |
518 | /// | |
519 | /// let slice = v.into_boxed_slice(); | |
520 | /// ``` | |
521 | /// | |
522 | /// Any excess capacity is removed: | |
523 | /// | |
524 | /// ``` | |
525 | /// let mut vec = Vec::with_capacity(10); | |
526 | /// vec.extend([1, 2, 3].iter().cloned()); | |
527 | /// | |
528 | /// assert_eq!(vec.capacity(), 10); | |
529 | /// let slice = vec.into_boxed_slice(); | |
530 | /// assert_eq!(slice.into_vec().capacity(), 3); | |
531 | /// ``` | |
c34b1796 | 532 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 533 | pub fn into_boxed_slice(mut self) -> Box<[T]> { |
1a4d82fc | 534 | unsafe { |
c1a9b12d SL |
535 | self.shrink_to_fit(); |
536 | let buf = ptr::read(&self.buf); | |
1a4d82fc | 537 | mem::forget(self); |
c1a9b12d | 538 | buf.into_box() |
1a4d82fc JJ |
539 | } |
540 | } | |
541 | ||
5bcae85e SL |
542 | /// Shortens the vector, keeping the first `len` elements and dropping |
543 | /// the rest. | |
1a4d82fc JJ |
544 | /// |
545 | /// If `len` is greater than the vector's current length, this has no | |
546 | /// effect. | |
547 | /// | |
5bcae85e SL |
548 | /// The [`drain`] method can emulate `truncate`, but causes the excess |
549 | /// elements to be returned instead of dropped. | |
550 | /// | |
8bb4bdeb XL |
551 | /// Note that this method has no effect on the allocated capacity |
552 | /// of the vector. | |
553 | /// | |
1a4d82fc JJ |
554 | /// # Examples |
555 | /// | |
5bcae85e SL |
556 | /// Truncating a five element vector to two elements: |
557 | /// | |
1a4d82fc | 558 | /// ``` |
92a42be0 | 559 | /// let mut vec = vec![1, 2, 3, 4, 5]; |
1a4d82fc | 560 | /// vec.truncate(2); |
c34b1796 | 561 | /// assert_eq!(vec, [1, 2]); |
1a4d82fc | 562 | /// ``` |
5bcae85e SL |
563 | /// |
564 | /// No truncation occurs when `len` is greater than the vector's current | |
565 | /// length: | |
566 | /// | |
567 | /// ``` | |
568 | /// let mut vec = vec![1, 2, 3]; | |
569 | /// vec.truncate(8); | |
570 | /// assert_eq!(vec, [1, 2, 3]); | |
571 | /// ``` | |
572 | /// | |
573 | /// Truncating when `len == 0` is equivalent to calling the [`clear`] | |
574 | /// method. | |
575 | /// | |
576 | /// ``` | |
577 | /// let mut vec = vec![1, 2, 3]; | |
578 | /// vec.truncate(0); | |
579 | /// assert_eq!(vec, []); | |
580 | /// ``` | |
581 | /// | |
582 | /// [`clear`]: #method.clear | |
583 | /// [`drain`]: #method.drain | |
85aaf69f SL |
584 | #[stable(feature = "rust1", since = "1.0.0")] |
585 | pub fn truncate(&mut self, len: usize) { | |
1a4d82fc JJ |
586 | unsafe { |
587 | // drop any extra elements | |
588 | while len < self.len { | |
54a0048b SL |
589 | // decrement len before the drop_in_place(), so a panic on Drop |
590 | // doesn't re-drop the just-failed value. | |
1a4d82fc | 591 | self.len -= 1; |
54a0048b SL |
592 | let len = self.len; |
593 | ptr::drop_in_place(self.get_unchecked_mut(len)); | |
1a4d82fc JJ |
594 | } |
595 | } | |
596 | } | |
597 | ||
9346a6ac | 598 | /// Extracts a slice containing the entire vector. |
62682a34 SL |
599 | /// |
600 | /// Equivalent to `&s[..]`. | |
5bcae85e SL |
601 | /// |
602 | /// # Examples | |
603 | /// | |
604 | /// ``` | |
605 | /// use std::io::{self, Write}; | |
606 | /// let buffer = vec![1, 2, 3, 5, 8]; | |
607 | /// io::sink().write(buffer.as_slice()).unwrap(); | |
608 | /// ``` | |
1a4d82fc | 609 | #[inline] |
9cc50fc6 | 610 | #[stable(feature = "vec_as_slice", since = "1.7.0")] |
c34b1796 AL |
611 | pub fn as_slice(&self) -> &[T] { |
612 | self | |
613 | } | |
614 | ||
62682a34 SL |
615 | /// Extracts a mutable slice of the entire vector. |
616 | /// | |
617 | /// Equivalent to `&mut s[..]`. | |
5bcae85e SL |
618 | /// |
619 | /// # Examples | |
620 | /// | |
621 | /// ``` | |
622 | /// use std::io::{self, Read}; | |
623 | /// let mut buffer = vec![0; 3]; | |
624 | /// io::repeat(0b101).read_exact(buffer.as_mut_slice()).unwrap(); | |
625 | /// ``` | |
c34b1796 | 626 | #[inline] |
9cc50fc6 | 627 | #[stable(feature = "vec_as_slice", since = "1.7.0")] |
85aaf69f | 628 | pub fn as_mut_slice(&mut self) -> &mut [T] { |
5bcae85e | 629 | self |
1a4d82fc JJ |
630 | } |
631 | ||
1a4d82fc JJ |
632 | /// Sets the length of a vector. |
633 | /// | |
634 | /// This will explicitly set the size of the vector, without actually | |
635 | /// modifying its buffers, so it is up to the caller to ensure that the | |
636 | /// vector is actually the specified size. | |
637 | /// | |
638 | /// # Examples | |
639 | /// | |
640 | /// ``` | |
5bcae85e SL |
641 | /// use std::ptr; |
642 | /// | |
643 | /// let mut vec = vec!['r', 'u', 's', 't']; | |
644 | /// | |
645 | /// unsafe { | |
646 | /// ptr::drop_in_place(&mut vec[3]); | |
647 | /// vec.set_len(3); | |
648 | /// } | |
649 | /// assert_eq!(vec, ['r', 'u', 's']); | |
650 | /// ``` | |
651 | /// | |
652 | /// In this example, there is a memory leak since the memory locations | |
653 | /// owned by the inner vectors were not freed prior to the `set_len` call: | |
654 | /// | |
655 | /// ``` | |
656 | /// let mut vec = vec![vec![1, 0, 0], | |
657 | /// vec![0, 1, 0], | |
658 | /// vec![0, 0, 1]]; | |
1a4d82fc | 659 | /// unsafe { |
5bcae85e SL |
660 | /// vec.set_len(0); |
661 | /// } | |
662 | /// ``` | |
663 | /// | |
664 | /// In this example, the vector gets expanded from zero to four items | |
665 | /// without any memory allocations occurring, resulting in vector | |
666 | /// values of unallocated memory: | |
667 | /// | |
668 | /// ``` | |
669 | /// let mut vec: Vec<char> = Vec::new(); | |
670 | /// | |
671 | /// unsafe { | |
672 | /// vec.set_len(4); | |
1a4d82fc JJ |
673 | /// } |
674 | /// ``` | |
675 | #[inline] | |
85aaf69f SL |
676 | #[stable(feature = "rust1", since = "1.0.0")] |
677 | pub unsafe fn set_len(&mut self, len: usize) { | |
1a4d82fc JJ |
678 | self.len = len; |
679 | } | |
680 | ||
cc61c64b XL |
681 | /// Removes an element from the vector and returns it. |
682 | /// | |
683 | /// The removed element is replaced by the last element of the vector. | |
1a4d82fc JJ |
684 | /// |
685 | /// This does not preserve ordering, but is O(1). | |
686 | /// | |
687 | /// # Panics | |
688 | /// | |
689 | /// Panics if `index` is out of bounds. | |
690 | /// | |
691 | /// # Examples | |
692 | /// | |
693 | /// ``` | |
694 | /// let mut v = vec!["foo", "bar", "baz", "qux"]; | |
695 | /// | |
696 | /// assert_eq!(v.swap_remove(1), "bar"); | |
c34b1796 | 697 | /// assert_eq!(v, ["foo", "qux", "baz"]); |
1a4d82fc JJ |
698 | /// |
699 | /// assert_eq!(v.swap_remove(0), "foo"); | |
c34b1796 | 700 | /// assert_eq!(v, ["baz", "qux"]); |
1a4d82fc JJ |
701 | /// ``` |
702 | #[inline] | |
85aaf69f SL |
703 | #[stable(feature = "rust1", since = "1.0.0")] |
704 | pub fn swap_remove(&mut self, index: usize) -> T { | |
1a4d82fc JJ |
705 | let length = self.len(); |
706 | self.swap(index, length - 1); | |
707 | self.pop().unwrap() | |
708 | } | |
709 | ||
710 | /// Inserts an element at position `index` within the vector, shifting all | |
7453a54e | 711 | /// elements after it to the right. |
1a4d82fc JJ |
712 | /// |
713 | /// # Panics | |
714 | /// | |
c30ab7b3 | 715 | /// Panics if `index` is out of bounds. |
1a4d82fc JJ |
716 | /// |
717 | /// # Examples | |
718 | /// | |
719 | /// ``` | |
85aaf69f | 720 | /// let mut vec = vec![1, 2, 3]; |
1a4d82fc | 721 | /// vec.insert(1, 4); |
c34b1796 | 722 | /// assert_eq!(vec, [1, 4, 2, 3]); |
1a4d82fc | 723 | /// vec.insert(4, 5); |
c34b1796 | 724 | /// assert_eq!(vec, [1, 4, 2, 3, 5]); |
1a4d82fc | 725 | /// ``` |
85aaf69f SL |
726 | #[stable(feature = "rust1", since = "1.0.0")] |
727 | pub fn insert(&mut self, index: usize, element: T) { | |
1a4d82fc JJ |
728 | let len = self.len(); |
729 | assert!(index <= len); | |
c1a9b12d | 730 | |
1a4d82fc | 731 | // space for the new element |
92a42be0 SL |
732 | if len == self.buf.cap() { |
733 | self.buf.double(); | |
734 | } | |
1a4d82fc | 735 | |
92a42be0 SL |
736 | unsafe { |
737 | // infallible | |
1a4d82fc JJ |
738 | // The spot to put the new value |
739 | { | |
85aaf69f | 740 | let p = self.as_mut_ptr().offset(index as isize); |
1a4d82fc JJ |
741 | // Shift everything over to make space. (Duplicating the |
742 | // `index`th element into two consecutive places.) | |
c1a9b12d | 743 | ptr::copy(p, p.offset(1), len - index); |
1a4d82fc JJ |
744 | // Write it in, overwriting the first copy of the `index`th |
745 | // element. | |
c1a9b12d | 746 | ptr::write(p, element); |
1a4d82fc JJ |
747 | } |
748 | self.set_len(len + 1); | |
749 | } | |
750 | } | |
751 | ||
752 | /// Removes and returns the element at position `index` within the vector, | |
7453a54e | 753 | /// shifting all elements after it to the left. |
1a4d82fc JJ |
754 | /// |
755 | /// # Panics | |
756 | /// | |
bd371182 | 757 | /// Panics if `index` is out of bounds. |
1a4d82fc JJ |
758 | /// |
759 | /// # Examples | |
760 | /// | |
761 | /// ``` | |
85aaf69f | 762 | /// let mut v = vec![1, 2, 3]; |
1a4d82fc | 763 | /// assert_eq!(v.remove(1), 2); |
c34b1796 | 764 | /// assert_eq!(v, [1, 3]); |
1a4d82fc | 765 | /// ``` |
85aaf69f SL |
766 | #[stable(feature = "rust1", since = "1.0.0")] |
767 | pub fn remove(&mut self, index: usize) -> T { | |
1a4d82fc JJ |
768 | let len = self.len(); |
769 | assert!(index < len); | |
92a42be0 SL |
770 | unsafe { |
771 | // infallible | |
1a4d82fc JJ |
772 | let ret; |
773 | { | |
774 | // the place we are taking from. | |
85aaf69f | 775 | let ptr = self.as_mut_ptr().offset(index as isize); |
1a4d82fc JJ |
776 | // copy it out, unsafely having a copy of the value on |
777 | // the stack and in the vector at the same time. | |
85aaf69f | 778 | ret = ptr::read(ptr); |
1a4d82fc JJ |
779 | |
780 | // Shift everything down to fill in that spot. | |
c1a9b12d | 781 | ptr::copy(ptr.offset(1), ptr, len - index - 1); |
1a4d82fc JJ |
782 | } |
783 | self.set_len(len - 1); | |
784 | ret | |
785 | } | |
786 | } | |
787 | ||
788 | /// Retains only the elements specified by the predicate. | |
789 | /// | |
c30ab7b3 | 790 | /// In other words, remove all elements `e` such that `f(&e)` returns `false`. |
1a4d82fc JJ |
791 | /// This method operates in place and preserves the order of the retained |
792 | /// elements. | |
793 | /// | |
794 | /// # Examples | |
795 | /// | |
796 | /// ``` | |
85aaf69f | 797 | /// let mut vec = vec![1, 2, 3, 4]; |
1a4d82fc | 798 | /// vec.retain(|&x| x%2 == 0); |
c34b1796 | 799 | /// assert_eq!(vec, [2, 4]); |
1a4d82fc | 800 | /// ``` |
85aaf69f | 801 | #[stable(feature = "rust1", since = "1.0.0")] |
92a42be0 SL |
802 | pub fn retain<F>(&mut self, mut f: F) |
803 | where F: FnMut(&T) -> bool | |
804 | { | |
1a4d82fc | 805 | let len = self.len(); |
85aaf69f | 806 | let mut del = 0; |
1a4d82fc | 807 | { |
85aaf69f | 808 | let v = &mut **self; |
1a4d82fc | 809 | |
85aaf69f | 810 | for i in 0..len { |
1a4d82fc JJ |
811 | if !f(&v[i]) { |
812 | del += 1; | |
813 | } else if del > 0 { | |
92a42be0 | 814 | v.swap(i - del, i); |
1a4d82fc JJ |
815 | } |
816 | } | |
817 | } | |
818 | if del > 0 { | |
819 | self.truncate(len - del); | |
820 | } | |
821 | } | |
822 | ||
041b39d2 XL |
823 | /// Removes all but the first of consecutive elements in the vector that resolve to the same |
824 | /// key. | |
c30ab7b3 SL |
825 | /// |
826 | /// If the vector is sorted, this removes all duplicates. | |
827 | /// | |
828 | /// # Examples | |
829 | /// | |
830 | /// ``` | |
c30ab7b3 SL |
831 | /// let mut vec = vec![10, 20, 21, 30, 20]; |
832 | /// | |
833 | /// vec.dedup_by_key(|i| *i / 10); | |
834 | /// | |
835 | /// assert_eq!(vec, [10, 20, 30, 20]); | |
836 | /// ``` | |
32a655c1 | 837 | #[stable(feature = "dedup_by", since = "1.16.0")] |
c30ab7b3 SL |
838 | #[inline] |
839 | pub fn dedup_by_key<F, K>(&mut self, mut key: F) where F: FnMut(&mut T) -> K, K: PartialEq { | |
840 | self.dedup_by(|a, b| key(a) == key(b)) | |
841 | } | |
842 | ||
041b39d2 XL |
843 | /// Removes all but the first of consecutive elements in the vector satisfying a given equality |
844 | /// relation. | |
cc61c64b XL |
845 | /// |
846 | /// The `same_bucket` function is passed references to two elements from the vector, and | |
041b39d2 XL |
847 | /// returns `true` if the elements compare equal, or `false` if they do not. The elements are |
848 | /// passed in opposite order from their order in the vector, so if `same_bucket(a, b)` returns | |
849 | /// `true`, `a` is removed. | |
c30ab7b3 SL |
850 | /// |
851 | /// If the vector is sorted, this removes all duplicates. | |
852 | /// | |
853 | /// # Examples | |
854 | /// | |
855 | /// ``` | |
c30ab7b3 SL |
856 | /// let mut vec = vec!["foo", "bar", "Bar", "baz", "bar"]; |
857 | /// | |
858 | /// vec.dedup_by(|a, b| a.eq_ignore_ascii_case(b)); | |
859 | /// | |
860 | /// assert_eq!(vec, ["foo", "bar", "baz", "bar"]); | |
861 | /// ``` | |
32a655c1 | 862 | #[stable(feature = "dedup_by", since = "1.16.0")] |
c30ab7b3 SL |
863 | pub fn dedup_by<F>(&mut self, mut same_bucket: F) where F: FnMut(&mut T, &mut T) -> bool { |
864 | unsafe { | |
865 | // Although we have a mutable reference to `self`, we cannot make | |
866 | // *arbitrary* changes. The `same_bucket` calls could panic, so we | |
867 | // must ensure that the vector is in a valid state at all time. | |
868 | // | |
869 | // The way that we handle this is by using swaps; we iterate | |
870 | // over all the elements, swapping as we go so that at the end | |
871 | // the elements we wish to keep are in the front, and those we | |
872 | // wish to reject are at the back. We can then truncate the | |
873 | // vector. This operation is still O(n). | |
874 | // | |
875 | // Example: We start in this state, where `r` represents "next | |
876 | // read" and `w` represents "next_write`. | |
877 | // | |
878 | // r | |
879 | // +---+---+---+---+---+---+ | |
880 | // | 0 | 1 | 1 | 2 | 3 | 3 | | |
881 | // +---+---+---+---+---+---+ | |
882 | // w | |
883 | // | |
884 | // Comparing self[r] against self[w-1], this is not a duplicate, so | |
885 | // we swap self[r] and self[w] (no effect as r==w) and then increment both | |
886 | // r and w, leaving us with: | |
887 | // | |
888 | // r | |
889 | // +---+---+---+---+---+---+ | |
890 | // | 0 | 1 | 1 | 2 | 3 | 3 | | |
891 | // +---+---+---+---+---+---+ | |
892 | // w | |
893 | // | |
894 | // Comparing self[r] against self[w-1], this value is a duplicate, | |
895 | // so we increment `r` but leave everything else unchanged: | |
896 | // | |
897 | // r | |
898 | // +---+---+---+---+---+---+ | |
899 | // | 0 | 1 | 1 | 2 | 3 | 3 | | |
900 | // +---+---+---+---+---+---+ | |
901 | // w | |
902 | // | |
903 | // Comparing self[r] against self[w-1], this is not a duplicate, | |
904 | // so swap self[r] and self[w] and advance r and w: | |
905 | // | |
906 | // r | |
907 | // +---+---+---+---+---+---+ | |
908 | // | 0 | 1 | 2 | 1 | 3 | 3 | | |
909 | // +---+---+---+---+---+---+ | |
910 | // w | |
911 | // | |
912 | // Not a duplicate, repeat: | |
913 | // | |
914 | // r | |
915 | // +---+---+---+---+---+---+ | |
916 | // | 0 | 1 | 2 | 3 | 1 | 3 | | |
917 | // +---+---+---+---+---+---+ | |
918 | // w | |
919 | // | |
920 | // Duplicate, advance r. End of vec. Truncate to w. | |
921 | ||
922 | let ln = self.len(); | |
923 | if ln <= 1 { | |
924 | return; | |
925 | } | |
926 | ||
927 | // Avoid bounds checks by using raw pointers. | |
928 | let p = self.as_mut_ptr(); | |
929 | let mut r: usize = 1; | |
930 | let mut w: usize = 1; | |
931 | ||
932 | while r < ln { | |
933 | let p_r = p.offset(r as isize); | |
934 | let p_wm1 = p.offset((w - 1) as isize); | |
935 | if !same_bucket(&mut *p_r, &mut *p_wm1) { | |
936 | if r != w { | |
937 | let p_w = p_wm1.offset(1); | |
938 | mem::swap(&mut *p_r, &mut *p_w); | |
939 | } | |
940 | w += 1; | |
941 | } | |
942 | r += 1; | |
943 | } | |
944 | ||
945 | self.truncate(w); | |
946 | } | |
947 | } | |
948 | ||
1a4d82fc JJ |
949 | /// Appends an element to the back of a collection. |
950 | /// | |
951 | /// # Panics | |
952 | /// | |
85aaf69f | 953 | /// Panics if the number of elements in the vector overflows a `usize`. |
1a4d82fc JJ |
954 | /// |
955 | /// # Examples | |
956 | /// | |
c34b1796 | 957 | /// ``` |
c1a9b12d | 958 | /// let mut vec = vec![1, 2]; |
1a4d82fc | 959 | /// vec.push(3); |
c34b1796 | 960 | /// assert_eq!(vec, [1, 2, 3]); |
1a4d82fc JJ |
961 | /// ``` |
962 | #[inline] | |
85aaf69f | 963 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 964 | pub fn push(&mut self, value: T) { |
c1a9b12d SL |
965 | // This will panic or abort if we would allocate > isize::MAX bytes |
966 | // or if the length increment would overflow for zero-sized types. | |
92a42be0 SL |
967 | if self.len == self.buf.cap() { |
968 | self.buf.double(); | |
969 | } | |
1a4d82fc | 970 | unsafe { |
c1a9b12d SL |
971 | let end = self.as_mut_ptr().offset(self.len as isize); |
972 | ptr::write(end, value); | |
1a4d82fc JJ |
973 | self.len += 1; |
974 | } | |
975 | } | |
976 | ||
cc61c64b XL |
977 | /// Returns a place for insertion at the back of the `Vec`. |
978 | /// | |
979 | /// Using this method with placement syntax is equivalent to [`push`](#method.push), | |
980 | /// but may be more efficient. | |
981 | /// | |
982 | /// # Examples | |
983 | /// | |
984 | /// ``` | |
985 | /// #![feature(collection_placement)] | |
986 | /// #![feature(placement_in_syntax)] | |
987 | /// | |
988 | /// let mut vec = vec![1, 2]; | |
989 | /// vec.place_back() <- 3; | |
990 | /// vec.place_back() <- 4; | |
991 | /// assert_eq!(&vec, &[1, 2, 3, 4]); | |
992 | /// ``` | |
993 | #[unstable(feature = "collection_placement", | |
994 | reason = "placement protocol is subject to change", | |
995 | issue = "30172")] | |
996 | pub fn place_back(&mut self) -> PlaceBack<T> { | |
997 | PlaceBack { vec: self } | |
998 | } | |
999 | ||
c30ab7b3 | 1000 | /// Removes the last element from a vector and returns it, or [`None`] if it |
e9174d1e | 1001 | /// is empty. |
1a4d82fc | 1002 | /// |
c30ab7b3 SL |
1003 | /// [`None`]: ../../std/option/enum.Option.html#variant.None |
1004 | /// | |
1a4d82fc JJ |
1005 | /// # Examples |
1006 | /// | |
c34b1796 | 1007 | /// ``` |
85aaf69f | 1008 | /// let mut vec = vec![1, 2, 3]; |
1a4d82fc | 1009 | /// assert_eq!(vec.pop(), Some(3)); |
c34b1796 | 1010 | /// assert_eq!(vec, [1, 2]); |
1a4d82fc JJ |
1011 | /// ``` |
1012 | #[inline] | |
85aaf69f | 1013 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
1014 | pub fn pop(&mut self) -> Option<T> { |
1015 | if self.len == 0 { | |
1016 | None | |
1017 | } else { | |
1018 | unsafe { | |
1019 | self.len -= 1; | |
1020 | Some(ptr::read(self.get_unchecked(self.len()))) | |
1021 | } | |
1022 | } | |
1023 | } | |
1024 | ||
85aaf69f SL |
1025 | /// Moves all the elements of `other` into `Self`, leaving `other` empty. |
1026 | /// | |
1027 | /// # Panics | |
1028 | /// | |
1029 | /// Panics if the number of elements in the vector overflows a `usize`. | |
1030 | /// | |
1031 | /// # Examples | |
1032 | /// | |
1033 | /// ``` | |
1034 | /// let mut vec = vec![1, 2, 3]; | |
1035 | /// let mut vec2 = vec![4, 5, 6]; | |
1036 | /// vec.append(&mut vec2); | |
c34b1796 AL |
1037 | /// assert_eq!(vec, [1, 2, 3, 4, 5, 6]); |
1038 | /// assert_eq!(vec2, []); | |
85aaf69f SL |
1039 | /// ``` |
1040 | #[inline] | |
e9174d1e | 1041 | #[stable(feature = "append", since = "1.4.0")] |
85aaf69f | 1042 | pub fn append(&mut self, other: &mut Self) { |
92a42be0 | 1043 | unsafe { |
cc61c64b | 1044 | self.append_elements(other.as_slice() as _); |
92a42be0 SL |
1045 | other.set_len(0); |
1046 | } | |
85aaf69f SL |
1047 | } |
1048 | ||
cc61c64b XL |
1049 | /// Appends elements to `Self` from other buffer. |
1050 | #[inline] | |
1051 | unsafe fn append_elements(&mut self, other: *const [T]) { | |
1052 | let count = (*other).len(); | |
1053 | self.reserve(count); | |
1054 | let len = self.len(); | |
1055 | ptr::copy_nonoverlapping(other as *const T, self.get_unchecked_mut(len), count); | |
1056 | self.len += count; | |
1057 | } | |
1058 | ||
7cac9316 | 1059 | /// Creates a draining iterator that removes the specified range in the vector |
9cc50fc6 | 1060 | /// and yields the removed items. |
d9579d0f | 1061 | /// |
32a655c1 SL |
1062 | /// Note 1: The element range is removed even if the iterator is only |
1063 | /// partially consumed or not consumed at all. | |
9cc50fc6 | 1064 | /// |
7cac9316 | 1065 | /// Note 2: It is unspecified how many elements are removed from the vector |
d9579d0f AL |
1066 | /// if the `Drain` value is leaked. |
1067 | /// | |
1068 | /// # Panics | |
1069 | /// | |
1070 | /// Panics if the starting point is greater than the end point or if | |
1071 | /// the end point is greater than the length of the vector. | |
1a4d82fc JJ |
1072 | /// |
1073 | /// # Examples | |
1074 | /// | |
1075 | /// ``` | |
d9579d0f | 1076 | /// let mut v = vec![1, 2, 3]; |
9cc50fc6 SL |
1077 | /// let u: Vec<_> = v.drain(1..).collect(); |
1078 | /// assert_eq!(v, &[1]); | |
1079 | /// assert_eq!(u, &[2, 3]); | |
1080 | /// | |
1081 | /// // A full range clears the vector | |
1082 | /// v.drain(..); | |
d9579d0f | 1083 | /// assert_eq!(v, &[]); |
1a4d82fc | 1084 | /// ``` |
92a42be0 SL |
1085 | #[stable(feature = "drain", since = "1.6.0")] |
1086 | pub fn drain<R>(&mut self, range: R) -> Drain<T> | |
1087 | where R: RangeArgument<usize> | |
1088 | { | |
d9579d0f AL |
1089 | // Memory safety |
1090 | // | |
1091 | // When the Drain is first created, it shortens the length of | |
1092 | // the source vector to make sure no uninitalized or moved-from elements | |
1093 | // are accessible at all if the Drain's destructor never gets to run. | |
1094 | // | |
1095 | // Drain will ptr::read out the values to remove. | |
1096 | // When finished, remaining tail of the vec is copied back to cover | |
1097 | // the hole, and the vector length is restored to the new length. | |
1098 | // | |
1099 | let len = self.len(); | |
32a655c1 SL |
1100 | let start = match range.start() { |
1101 | Included(&n) => n, | |
1102 | Excluded(&n) => n + 1, | |
1103 | Unbounded => 0, | |
1104 | }; | |
1105 | let end = match range.end() { | |
1106 | Included(&n) => n + 1, | |
1107 | Excluded(&n) => n, | |
1108 | Unbounded => len, | |
1109 | }; | |
d9579d0f AL |
1110 | assert!(start <= end); |
1111 | assert!(end <= len); | |
1112 | ||
1a4d82fc | 1113 | unsafe { |
d9579d0f AL |
1114 | // set self.vec length's to start, to be safe in case Drain is leaked |
1115 | self.set_len(start); | |
1116 | // Use the borrow in the IterMut to indicate borrowing behavior of the | |
1117 | // whole Drain iterator (like &mut T). | |
92a42be0 SL |
1118 | let range_slice = slice::from_raw_parts_mut(self.as_mut_ptr().offset(start as isize), |
1119 | end - start); | |
1a4d82fc | 1120 | Drain { |
d9579d0f AL |
1121 | tail_start: end, |
1122 | tail_len: len - end, | |
5bcae85e | 1123 | iter: range_slice.iter(), |
3b2f2976 | 1124 | vec: Shared::from(self), |
1a4d82fc JJ |
1125 | } |
1126 | } | |
1127 | } | |
1128 | ||
1129 | /// Clears the vector, removing all values. | |
1130 | /// | |
8bb4bdeb XL |
1131 | /// Note that this method has no effect on the allocated capacity |
1132 | /// of the vector. | |
1133 | /// | |
1a4d82fc JJ |
1134 | /// # Examples |
1135 | /// | |
1136 | /// ``` | |
85aaf69f | 1137 | /// let mut v = vec![1, 2, 3]; |
1a4d82fc JJ |
1138 | /// |
1139 | /// v.clear(); | |
1140 | /// | |
1141 | /// assert!(v.is_empty()); | |
1142 | /// ``` | |
1143 | #[inline] | |
85aaf69f | 1144 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
1145 | pub fn clear(&mut self) { |
1146 | self.truncate(0) | |
1147 | } | |
1148 | ||
7cac9316 XL |
1149 | /// Returns the number of elements in the vector, also referred to |
1150 | /// as its 'length'. | |
1a4d82fc JJ |
1151 | /// |
1152 | /// # Examples | |
1153 | /// | |
1154 | /// ``` | |
85aaf69f | 1155 | /// let a = vec![1, 2, 3]; |
1a4d82fc JJ |
1156 | /// assert_eq!(a.len(), 3); |
1157 | /// ``` | |
1158 | #[inline] | |
85aaf69f | 1159 | #[stable(feature = "rust1", since = "1.0.0")] |
92a42be0 SL |
1160 | pub fn len(&self) -> usize { |
1161 | self.len | |
1162 | } | |
1a4d82fc JJ |
1163 | |
1164 | /// Returns `true` if the vector contains no elements. | |
1165 | /// | |
1166 | /// # Examples | |
1167 | /// | |
1168 | /// ``` | |
1169 | /// let mut v = Vec::new(); | |
1170 | /// assert!(v.is_empty()); | |
1171 | /// | |
85aaf69f | 1172 | /// v.push(1); |
1a4d82fc JJ |
1173 | /// assert!(!v.is_empty()); |
1174 | /// ``` | |
85aaf69f | 1175 | #[stable(feature = "rust1", since = "1.0.0")] |
92a42be0 SL |
1176 | pub fn is_empty(&self) -> bool { |
1177 | self.len() == 0 | |
1178 | } | |
1a4d82fc | 1179 | |
85aaf69f SL |
1180 | /// Splits the collection into two at the given index. |
1181 | /// | |
1182 | /// Returns a newly allocated `Self`. `self` contains elements `[0, at)`, | |
1183 | /// and the returned `Self` contains elements `[at, len)`. | |
1184 | /// | |
1185 | /// Note that the capacity of `self` does not change. | |
1186 | /// | |
1187 | /// # Panics | |
1188 | /// | |
1189 | /// Panics if `at > len`. | |
1190 | /// | |
1191 | /// # Examples | |
1192 | /// | |
1193 | /// ``` | |
1194 | /// let mut vec = vec![1,2,3]; | |
1195 | /// let vec2 = vec.split_off(1); | |
c34b1796 AL |
1196 | /// assert_eq!(vec, [1]); |
1197 | /// assert_eq!(vec2, [2, 3]); | |
85aaf69f SL |
1198 | /// ``` |
1199 | #[inline] | |
e9174d1e | 1200 | #[stable(feature = "split_off", since = "1.4.0")] |
85aaf69f SL |
1201 | pub fn split_off(&mut self, at: usize) -> Self { |
1202 | assert!(at <= self.len(), "`at` out of bounds"); | |
1203 | ||
1204 | let other_len = self.len - at; | |
1205 | let mut other = Vec::with_capacity(other_len); | |
1206 | ||
1207 | // Unsafely `set_len` and copy items to `other`. | |
1208 | unsafe { | |
1209 | self.set_len(at); | |
1210 | other.set_len(other_len); | |
1211 | ||
92a42be0 SL |
1212 | ptr::copy_nonoverlapping(self.as_ptr().offset(at as isize), |
1213 | other.as_mut_ptr(), | |
1214 | other.len()); | |
85aaf69f SL |
1215 | } |
1216 | other | |
1217 | } | |
1a4d82fc JJ |
1218 | } |
1219 | ||
1220 | impl<T: Clone> Vec<T> { | |
7cac9316 | 1221 | /// Resizes the `Vec` in-place so that `len` is equal to `new_len`. |
1a4d82fc | 1222 | /// |
7cac9316 | 1223 | /// If `new_len` is greater than `len`, the `Vec` is extended by the |
92a42be0 | 1224 | /// difference, with each additional slot filled with `value`. |
7cac9316 XL |
1225 | /// If `new_len` is less than `len`, the `Vec` is simply truncated. |
1226 | /// | |
1227 | /// This method requires `Clone` to clone the passed value. If you'd | |
1228 | /// rather create a value with `Default` instead, see [`resize_default`]. | |
1a4d82fc JJ |
1229 | /// |
1230 | /// # Examples | |
1231 | /// | |
1232 | /// ``` | |
1233 | /// let mut vec = vec!["hello"]; | |
1234 | /// vec.resize(3, "world"); | |
c34b1796 | 1235 | /// assert_eq!(vec, ["hello", "world", "world"]); |
1a4d82fc | 1236 | /// |
85aaf69f | 1237 | /// let mut vec = vec![1, 2, 3, 4]; |
1a4d82fc | 1238 | /// vec.resize(2, 0); |
c34b1796 | 1239 | /// assert_eq!(vec, [1, 2]); |
1a4d82fc | 1240 | /// ``` |
7cac9316 XL |
1241 | /// |
1242 | /// [`resize_default`]: #method.resize_default | |
b039eaaf | 1243 | #[stable(feature = "vec_resize", since = "1.5.0")] |
85aaf69f | 1244 | pub fn resize(&mut self, new_len: usize, value: T) { |
1a4d82fc JJ |
1245 | let len = self.len(); |
1246 | ||
1247 | if new_len > len { | |
7cac9316 | 1248 | self.extend_with(new_len - len, ExtendElement(value)) |
1a4d82fc JJ |
1249 | } else { |
1250 | self.truncate(new_len); | |
1251 | } | |
1252 | } | |
1253 | ||
7cac9316 XL |
1254 | /// Clones and appends all elements in a slice to the `Vec`. |
1255 | /// | |
1256 | /// Iterates over the slice `other`, clones each element, and then appends | |
1257 | /// it to this `Vec`. The `other` vector is traversed in-order. | |
1258 | /// | |
1259 | /// Note that this function is same as `extend` except that it is | |
1260 | /// specialized to work with slices instead. If and when Rust gets | |
1261 | /// specialization this function will likely be deprecated (but still | |
1262 | /// available). | |
1263 | /// | |
1264 | /// # Examples | |
1265 | /// | |
1266 | /// ``` | |
1267 | /// let mut vec = vec![1]; | |
1268 | /// vec.extend_from_slice(&[2, 3, 4]); | |
1269 | /// assert_eq!(vec, [1, 2, 3, 4]); | |
1270 | /// ``` | |
1271 | #[stable(feature = "vec_extend_from_slice", since = "1.6.0")] | |
1272 | pub fn extend_from_slice(&mut self, other: &[T]) { | |
1273 | self.spec_extend(other.iter()) | |
1274 | } | |
1275 | } | |
1276 | ||
1277 | impl<T: Default> Vec<T> { | |
1278 | /// Resizes the `Vec` in-place so that `len` is equal to `new_len`. | |
1279 | /// | |
1280 | /// If `new_len` is greater than `len`, the `Vec` is extended by the | |
1281 | /// difference, with each additional slot filled with `Default::default()`. | |
1282 | /// If `new_len` is less than `len`, the `Vec` is simply truncated. | |
1283 | /// | |
1284 | /// This method uses `Default` to create new values on every push. If | |
1285 | /// you'd rather `Clone` a given value, use [`resize`]. | |
1286 | /// | |
1287 | /// | |
1288 | /// # Examples | |
1289 | /// | |
1290 | /// ``` | |
1291 | /// #![feature(vec_resize_default)] | |
1292 | /// | |
1293 | /// let mut vec = vec![1, 2, 3]; | |
1294 | /// vec.resize_default(5); | |
1295 | /// assert_eq!(vec, [1, 2, 3, 0, 0]); | |
1296 | /// | |
1297 | /// let mut vec = vec![1, 2, 3, 4]; | |
1298 | /// vec.resize_default(2); | |
1299 | /// assert_eq!(vec, [1, 2]); | |
1300 | /// ``` | |
1301 | /// | |
1302 | /// [`resize`]: #method.resize | |
1303 | #[unstable(feature = "vec_resize_default", issue = "41758")] | |
1304 | pub fn resize_default(&mut self, new_len: usize) { | |
1305 | let len = self.len(); | |
1306 | ||
1307 | if new_len > len { | |
1308 | self.extend_with(new_len - len, ExtendDefault); | |
1309 | } else { | |
1310 | self.truncate(new_len); | |
1311 | } | |
1312 | } | |
1313 | } | |
1314 | ||
1315 | // This code generalises `extend_with_{element,default}`. | |
1316 | trait ExtendWith<T> { | |
1317 | fn next(&self) -> T; | |
1318 | fn last(self) -> T; | |
1319 | } | |
1320 | ||
1321 | struct ExtendElement<T>(T); | |
1322 | impl<T: Clone> ExtendWith<T> for ExtendElement<T> { | |
1323 | fn next(&self) -> T { self.0.clone() } | |
1324 | fn last(self) -> T { self.0 } | |
1325 | } | |
1326 | ||
1327 | struct ExtendDefault; | |
1328 | impl<T: Default> ExtendWith<T> for ExtendDefault { | |
1329 | fn next(&self) -> T { Default::default() } | |
1330 | fn last(self) -> T { Default::default() } | |
1331 | } | |
1332 | impl<T> Vec<T> { | |
1333 | /// Extend the vector by `n` values, using the given generator. | |
1334 | fn extend_with<E: ExtendWith<T>>(&mut self, n: usize, value: E) { | |
c1a9b12d SL |
1335 | self.reserve(n); |
1336 | ||
1337 | unsafe { | |
9e0c209e SL |
1338 | let mut ptr = self.as_mut_ptr().offset(self.len() as isize); |
1339 | // Use SetLenOnDrop to work around bug where compiler | |
8bb4bdeb | 1340 | // may not realize the store through `ptr` through self.set_len() |
9e0c209e SL |
1341 | // don't alias. |
1342 | let mut local_len = SetLenOnDrop::new(&mut self.len); | |
1343 | ||
c1a9b12d | 1344 | // Write all elements except the last one |
9e0c209e | 1345 | for _ in 1..n { |
7cac9316 | 1346 | ptr::write(ptr, value.next()); |
c1a9b12d | 1347 | ptr = ptr.offset(1); |
7cac9316 | 1348 | // Increment the length in every step in case next() panics |
9e0c209e | 1349 | local_len.increment_len(1); |
c1a9b12d SL |
1350 | } |
1351 | ||
1352 | if n > 0 { | |
1353 | // We can write the last element directly without cloning needlessly | |
7cac9316 | 1354 | ptr::write(ptr, value.last()); |
9e0c209e | 1355 | local_len.increment_len(1); |
c1a9b12d | 1356 | } |
9e0c209e SL |
1357 | |
1358 | // len set by scope guard | |
c1a9b12d SL |
1359 | } |
1360 | } | |
1a4d82fc JJ |
1361 | } |
1362 | ||
9e0c209e SL |
1363 | // Set the length of the vec when the `SetLenOnDrop` value goes out of scope. |
1364 | // | |
1365 | // The idea is: The length field in SetLenOnDrop is a local variable | |
1366 | // that the optimizer will see does not alias with any stores through the Vec's data | |
1367 | // pointer. This is a workaround for alias analysis issue #32155 | |
1368 | struct SetLenOnDrop<'a> { | |
1369 | len: &'a mut usize, | |
1370 | local_len: usize, | |
1371 | } | |
1372 | ||
1373 | impl<'a> SetLenOnDrop<'a> { | |
1374 | #[inline] | |
1375 | fn new(len: &'a mut usize) -> Self { | |
1376 | SetLenOnDrop { local_len: *len, len: len } | |
1377 | } | |
1378 | ||
1379 | #[inline] | |
1380 | fn increment_len(&mut self, increment: usize) { | |
1381 | self.local_len += increment; | |
1382 | } | |
1383 | } | |
1384 | ||
1385 | impl<'a> Drop for SetLenOnDrop<'a> { | |
1386 | #[inline] | |
1387 | fn drop(&mut self) { | |
1388 | *self.len = self.local_len; | |
1389 | } | |
1390 | } | |
1391 | ||
1a4d82fc JJ |
1392 | impl<T: PartialEq> Vec<T> { |
1393 | /// Removes consecutive repeated elements in the vector. | |
1394 | /// | |
1395 | /// If the vector is sorted, this removes all duplicates. | |
1396 | /// | |
1397 | /// # Examples | |
1398 | /// | |
1399 | /// ``` | |
85aaf69f | 1400 | /// let mut vec = vec![1, 2, 2, 3, 2]; |
1a4d82fc JJ |
1401 | /// |
1402 | /// vec.dedup(); | |
1403 | /// | |
c34b1796 | 1404 | /// assert_eq!(vec, [1, 2, 3, 2]); |
1a4d82fc | 1405 | /// ``` |
85aaf69f | 1406 | #[stable(feature = "rust1", since = "1.0.0")] |
c30ab7b3 | 1407 | #[inline] |
1a4d82fc | 1408 | pub fn dedup(&mut self) { |
c30ab7b3 | 1409 | self.dedup_by(|a, b| a == b) |
1a4d82fc | 1410 | } |
8bb4bdeb XL |
1411 | |
1412 | /// Removes the first instance of `item` from the vector if the item exists. | |
1413 | /// | |
1414 | /// # Examples | |
1415 | /// | |
1416 | /// ``` | |
cc61c64b | 1417 | /// # #![feature(vec_remove_item)] |
8bb4bdeb XL |
1418 | /// let mut vec = vec![1, 2, 3, 1]; |
1419 | /// | |
1420 | /// vec.remove_item(&1); | |
1421 | /// | |
1422 | /// assert_eq!(vec, vec![2, 3, 1]); | |
1423 | /// ``` | |
1424 | #[unstable(feature = "vec_remove_item", reason = "recently added", issue = "40062")] | |
1425 | pub fn remove_item(&mut self, item: &T) -> Option<T> { | |
1426 | let pos = match self.iter().position(|x| *x == *item) { | |
1427 | Some(x) => x, | |
1428 | None => return None, | |
1429 | }; | |
1430 | Some(self.remove(pos)) | |
1431 | } | |
1a4d82fc JJ |
1432 | } |
1433 | ||
1434 | //////////////////////////////////////////////////////////////////////////////// | |
1435 | // Internal methods and functions | |
1436 | //////////////////////////////////////////////////////////////////////////////// | |
1437 | ||
85aaf69f SL |
1438 | #[doc(hidden)] |
1439 | #[stable(feature = "rust1", since = "1.0.0")] | |
1440 | pub fn from_elem<T: Clone>(elem: T, n: usize) -> Vec<T> { | |
cc61c64b XL |
1441 | <T as SpecFromElem>::from_elem(elem, n) |
1442 | } | |
1443 | ||
1444 | // Specialization trait used for Vec::from_elem | |
1445 | trait SpecFromElem: Sized { | |
1446 | fn from_elem(elem: Self, n: usize) -> Vec<Self>; | |
1447 | } | |
1448 | ||
1449 | impl<T: Clone> SpecFromElem for T { | |
1450 | default fn from_elem(elem: Self, n: usize) -> Vec<Self> { | |
1451 | let mut v = Vec::with_capacity(n); | |
7cac9316 | 1452 | v.extend_with(n, ExtendElement(elem)); |
cc61c64b XL |
1453 | v |
1454 | } | |
85aaf69f SL |
1455 | } |
1456 | ||
cc61c64b XL |
1457 | impl SpecFromElem for u8 { |
1458 | #[inline] | |
1459 | fn from_elem(elem: u8, n: usize) -> Vec<u8> { | |
1460 | if elem == 0 { | |
1461 | return Vec { | |
1462 | buf: RawVec::with_capacity_zeroed(n), | |
1463 | len: n, | |
1464 | } | |
1465 | } | |
1466 | unsafe { | |
1467 | let mut v = Vec::with_capacity(n); | |
1468 | ptr::write_bytes(v.as_mut_ptr(), elem, n); | |
1469 | v.set_len(n); | |
1470 | v | |
1471 | } | |
1472 | } | |
1473 | } | |
1474 | ||
1475 | macro_rules! impl_spec_from_elem { | |
1476 | ($t: ty, $is_zero: expr) => { | |
1477 | impl SpecFromElem for $t { | |
1478 | #[inline] | |
1479 | fn from_elem(elem: $t, n: usize) -> Vec<$t> { | |
1480 | if $is_zero(elem) { | |
1481 | return Vec { | |
1482 | buf: RawVec::with_capacity_zeroed(n), | |
1483 | len: n, | |
1484 | } | |
1485 | } | |
1486 | let mut v = Vec::with_capacity(n); | |
7cac9316 | 1487 | v.extend_with(n, ExtendElement(elem)); |
cc61c64b XL |
1488 | v |
1489 | } | |
1490 | } | |
1491 | }; | |
1492 | } | |
1493 | ||
1494 | impl_spec_from_elem!(i8, |x| x == 0); | |
1495 | impl_spec_from_elem!(i16, |x| x == 0); | |
1496 | impl_spec_from_elem!(i32, |x| x == 0); | |
1497 | impl_spec_from_elem!(i64, |x| x == 0); | |
1498 | impl_spec_from_elem!(i128, |x| x == 0); | |
1499 | impl_spec_from_elem!(isize, |x| x == 0); | |
1500 | ||
1501 | impl_spec_from_elem!(u16, |x| x == 0); | |
1502 | impl_spec_from_elem!(u32, |x| x == 0); | |
1503 | impl_spec_from_elem!(u64, |x| x == 0); | |
1504 | impl_spec_from_elem!(u128, |x| x == 0); | |
1505 | impl_spec_from_elem!(usize, |x| x == 0); | |
1506 | ||
1507 | impl_spec_from_elem!(f32, |x: f32| x == 0. && x.is_sign_positive()); | |
1508 | impl_spec_from_elem!(f64, |x: f64| x == 0. && x.is_sign_positive()); | |
1509 | ||
1a4d82fc JJ |
1510 | //////////////////////////////////////////////////////////////////////////////// |
1511 | // Common trait implementations for Vec | |
1512 | //////////////////////////////////////////////////////////////////////////////// | |
1513 | ||
bd371182 | 1514 | #[stable(feature = "rust1", since = "1.0.0")] |
92a42be0 | 1515 | impl<T: Clone> Clone for Vec<T> { |
c34b1796 | 1516 | #[cfg(not(test))] |
92a42be0 SL |
1517 | fn clone(&self) -> Vec<T> { |
1518 | <[T]>::to_vec(&**self) | |
1519 | } | |
c34b1796 AL |
1520 | |
1521 | // HACK(japaric): with cfg(test) the inherent `[T]::to_vec` method, which is | |
1522 | // required for this method definition, is not available. Instead use the | |
1523 | // `slice::to_vec` function which is only available with cfg(test) | |
1524 | // NB see the slice::hack module in slice.rs for more information | |
1525 | #[cfg(test)] | |
1526 | fn clone(&self) -> Vec<T> { | |
1527 | ::slice::to_vec(&**self) | |
1528 | } | |
1a4d82fc JJ |
1529 | |
1530 | fn clone_from(&mut self, other: &Vec<T>) { | |
cc61c64b | 1531 | other.as_slice().clone_into(self); |
1a4d82fc JJ |
1532 | } |
1533 | } | |
1534 | ||
85aaf69f | 1535 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f | 1536 | impl<T: Hash> Hash for Vec<T> { |
1a4d82fc | 1537 | #[inline] |
85aaf69f SL |
1538 | fn hash<H: hash::Hasher>(&self, state: &mut H) { |
1539 | Hash::hash(&**self, state) | |
1a4d82fc JJ |
1540 | } |
1541 | } | |
1542 | ||
85aaf69f | 1543 | #[stable(feature = "rust1", since = "1.0.0")] |
abe05a73 | 1544 | #[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"] |
85aaf69f | 1545 | impl<T> Index<usize> for Vec<T> { |
1a4d82fc JJ |
1546 | type Output = T; |
1547 | ||
1548 | #[inline] | |
c34b1796 | 1549 | fn index(&self, index: usize) -> &T { |
85aaf69f | 1550 | // NB built-in indexing via `&[T]` |
c34b1796 | 1551 | &(**self)[index] |
1a4d82fc JJ |
1552 | } |
1553 | } | |
1554 | ||
85aaf69f | 1555 | #[stable(feature = "rust1", since = "1.0.0")] |
abe05a73 | 1556 | #[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"] |
85aaf69f | 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 | ||
85aaf69f | 1565 | #[stable(feature = "rust1", since = "1.0.0")] |
abe05a73 | 1566 | #[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"] |
85aaf69f | 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 | } | |
abe05a73 | 1575 | |
85aaf69f | 1576 | #[stable(feature = "rust1", since = "1.0.0")] |
abe05a73 | 1577 | #[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"] |
85aaf69f | 1578 | impl<T> ops::Index<ops::RangeTo<usize>> for Vec<T> { |
1a4d82fc | 1579 | type Output = [T]; |
c34b1796 | 1580 | |
1a4d82fc | 1581 | #[inline] |
c34b1796 | 1582 | fn index(&self, index: ops::RangeTo<usize>) -> &[T] { |
85aaf69f | 1583 | Index::index(&**self, index) |
1a4d82fc JJ |
1584 | } |
1585 | } | |
abe05a73 | 1586 | |
85aaf69f | 1587 | #[stable(feature = "rust1", since = "1.0.0")] |
abe05a73 | 1588 | #[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"] |
85aaf69f | 1589 | impl<T> ops::Index<ops::RangeFrom<usize>> for Vec<T> { |
1a4d82fc | 1590 | type Output = [T]; |
c34b1796 | 1591 | |
1a4d82fc | 1592 | #[inline] |
c34b1796 | 1593 | fn index(&self, index: ops::RangeFrom<usize>) -> &[T] { |
85aaf69f | 1594 | Index::index(&**self, index) |
1a4d82fc JJ |
1595 | } |
1596 | } | |
abe05a73 | 1597 | |
85aaf69f | 1598 | #[stable(feature = "rust1", since = "1.0.0")] |
abe05a73 | 1599 | #[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"] |
85aaf69f | 1600 | impl<T> ops::Index<ops::RangeFull> for Vec<T> { |
1a4d82fc | 1601 | type Output = [T]; |
c34b1796 | 1602 | |
1a4d82fc | 1603 | #[inline] |
c34b1796 AL |
1604 | fn index(&self, _index: ops::RangeFull) -> &[T] { |
1605 | self | |
1a4d82fc JJ |
1606 | } |
1607 | } | |
abe05a73 | 1608 | |
54a0048b | 1609 | #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")] |
abe05a73 | 1610 | #[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"] |
54a0048b SL |
1611 | impl<T> ops::Index<ops::RangeInclusive<usize>> for Vec<T> { |
1612 | type Output = [T]; | |
1613 | ||
1614 | #[inline] | |
1615 | fn index(&self, index: ops::RangeInclusive<usize>) -> &[T] { | |
1616 | Index::index(&**self, index) | |
1617 | } | |
1618 | } | |
abe05a73 | 1619 | |
54a0048b | 1620 | #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")] |
abe05a73 | 1621 | #[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"] |
54a0048b SL |
1622 | impl<T> ops::Index<ops::RangeToInclusive<usize>> for Vec<T> { |
1623 | type Output = [T]; | |
1624 | ||
1625 | #[inline] | |
1626 | fn index(&self, index: ops::RangeToInclusive<usize>) -> &[T] { | |
1627 | Index::index(&**self, index) | |
1628 | } | |
1629 | } | |
1a4d82fc | 1630 | |
85aaf69f | 1631 | #[stable(feature = "rust1", since = "1.0.0")] |
abe05a73 | 1632 | #[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"] |
85aaf69f | 1633 | impl<T> ops::IndexMut<ops::Range<usize>> for Vec<T> { |
1a4d82fc | 1634 | #[inline] |
c34b1796 | 1635 | fn index_mut(&mut self, index: ops::Range<usize>) -> &mut [T] { |
85aaf69f | 1636 | IndexMut::index_mut(&mut **self, index) |
1a4d82fc JJ |
1637 | } |
1638 | } | |
abe05a73 | 1639 | |
85aaf69f | 1640 | #[stable(feature = "rust1", since = "1.0.0")] |
abe05a73 | 1641 | #[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"] |
85aaf69f | 1642 | impl<T> ops::IndexMut<ops::RangeTo<usize>> for Vec<T> { |
1a4d82fc | 1643 | #[inline] |
c34b1796 | 1644 | fn index_mut(&mut self, index: ops::RangeTo<usize>) -> &mut [T] { |
85aaf69f | 1645 | IndexMut::index_mut(&mut **self, index) |
1a4d82fc JJ |
1646 | } |
1647 | } | |
abe05a73 | 1648 | |
85aaf69f | 1649 | #[stable(feature = "rust1", since = "1.0.0")] |
abe05a73 | 1650 | #[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"] |
85aaf69f | 1651 | impl<T> ops::IndexMut<ops::RangeFrom<usize>> for Vec<T> { |
1a4d82fc | 1652 | #[inline] |
c34b1796 | 1653 | fn index_mut(&mut self, index: ops::RangeFrom<usize>) -> &mut [T] { |
85aaf69f | 1654 | IndexMut::index_mut(&mut **self, index) |
1a4d82fc JJ |
1655 | } |
1656 | } | |
abe05a73 | 1657 | |
85aaf69f | 1658 | #[stable(feature = "rust1", since = "1.0.0")] |
abe05a73 | 1659 | #[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"] |
85aaf69f | 1660 | impl<T> ops::IndexMut<ops::RangeFull> for Vec<T> { |
1a4d82fc | 1661 | #[inline] |
c34b1796 AL |
1662 | fn index_mut(&mut self, _index: ops::RangeFull) -> &mut [T] { |
1663 | self | |
1a4d82fc JJ |
1664 | } |
1665 | } | |
abe05a73 | 1666 | |
54a0048b | 1667 | #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")] |
abe05a73 | 1668 | #[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"] |
54a0048b SL |
1669 | impl<T> ops::IndexMut<ops::RangeInclusive<usize>> for Vec<T> { |
1670 | #[inline] | |
1671 | fn index_mut(&mut self, index: ops::RangeInclusive<usize>) -> &mut [T] { | |
1672 | IndexMut::index_mut(&mut **self, index) | |
1673 | } | |
1674 | } | |
abe05a73 | 1675 | |
54a0048b | 1676 | #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")] |
abe05a73 | 1677 | #[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"] |
54a0048b SL |
1678 | impl<T> ops::IndexMut<ops::RangeToInclusive<usize>> for Vec<T> { |
1679 | #[inline] | |
1680 | fn index_mut(&mut self, index: ops::RangeToInclusive<usize>) -> &mut [T] { | |
1681 | IndexMut::index_mut(&mut **self, index) | |
1682 | } | |
1683 | } | |
1a4d82fc | 1684 | |
85aaf69f | 1685 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
1686 | impl<T> ops::Deref for Vec<T> { |
1687 | type Target = [T]; | |
1688 | ||
c34b1796 AL |
1689 | fn deref(&self) -> &[T] { |
1690 | unsafe { | |
c1a9b12d | 1691 | let p = self.buf.ptr(); |
e9174d1e | 1692 | assume(!p.is_null()); |
c34b1796 AL |
1693 | slice::from_raw_parts(p, self.len) |
1694 | } | |
1695 | } | |
1a4d82fc JJ |
1696 | } |
1697 | ||
85aaf69f | 1698 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 1699 | impl<T> ops::DerefMut for Vec<T> { |
c34b1796 AL |
1700 | fn deref_mut(&mut self) -> &mut [T] { |
1701 | unsafe { | |
c1a9b12d | 1702 | let ptr = self.buf.ptr(); |
c34b1796 AL |
1703 | assume(!ptr.is_null()); |
1704 | slice::from_raw_parts_mut(ptr, self.len) | |
1705 | } | |
1706 | } | |
1a4d82fc JJ |
1707 | } |
1708 | ||
85aaf69f | 1709 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
1710 | impl<T> FromIterator<T> for Vec<T> { |
1711 | #[inline] | |
54a0048b | 1712 | fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Vec<T> { |
cc61c64b | 1713 | <Self as SpecExtend<T, I::IntoIter>>::from_iter(iter.into_iter()) |
1a4d82fc JJ |
1714 | } |
1715 | } | |
1716 | ||
85aaf69f SL |
1717 | #[stable(feature = "rust1", since = "1.0.0")] |
1718 | impl<T> IntoIterator for Vec<T> { | |
1719 | type Item = T; | |
1720 | type IntoIter = IntoIter<T>; | |
1721 | ||
9346a6ac AL |
1722 | /// Creates a consuming iterator, that is, one that moves each value out of |
1723 | /// the vector (from start to end). The vector cannot be used after calling | |
1724 | /// this. | |
1725 | /// | |
1726 | /// # Examples | |
1727 | /// | |
1728 | /// ``` | |
1729 | /// let v = vec!["a".to_string(), "b".to_string()]; | |
1730 | /// for s in v.into_iter() { | |
1731 | /// // s has type String, not &String | |
1732 | /// println!("{}", s); | |
1733 | /// } | |
1734 | /// ``` | |
1735 | #[inline] | |
c1a9b12d | 1736 | fn into_iter(mut self) -> IntoIter<T> { |
9346a6ac | 1737 | unsafe { |
5bcae85e SL |
1738 | let begin = self.as_mut_ptr(); |
1739 | assume(!begin.is_null()); | |
9346a6ac | 1740 | let end = if mem::size_of::<T>() == 0 { |
5bcae85e | 1741 | arith_offset(begin as *const i8, self.len() as isize) as *const T |
9346a6ac | 1742 | } else { |
5bcae85e | 1743 | begin.offset(self.len() as isize) as *const T |
9346a6ac | 1744 | }; |
5bcae85e | 1745 | let cap = self.buf.cap(); |
9346a6ac | 1746 | mem::forget(self); |
92a42be0 | 1747 | IntoIter { |
3b2f2976 XL |
1748 | buf: Shared::new_unchecked(begin), |
1749 | cap, | |
92a42be0 | 1750 | ptr: begin, |
3b2f2976 | 1751 | end, |
92a42be0 | 1752 | } |
9346a6ac | 1753 | } |
85aaf69f SL |
1754 | } |
1755 | } | |
1756 | ||
1757 | #[stable(feature = "rust1", since = "1.0.0")] | |
1758 | impl<'a, T> IntoIterator for &'a Vec<T> { | |
1759 | type Item = &'a T; | |
1760 | type IntoIter = slice::Iter<'a, T>; | |
1761 | ||
1762 | fn into_iter(self) -> slice::Iter<'a, T> { | |
1763 | self.iter() | |
1764 | } | |
1765 | } | |
1766 | ||
1767 | #[stable(feature = "rust1", since = "1.0.0")] | |
1768 | impl<'a, T> IntoIterator for &'a mut Vec<T> { | |
1769 | type Item = &'a mut T; | |
1770 | type IntoIter = slice::IterMut<'a, T>; | |
1771 | ||
3b2f2976 | 1772 | fn into_iter(self) -> slice::IterMut<'a, T> { |
85aaf69f SL |
1773 | self.iter_mut() |
1774 | } | |
1775 | } | |
1776 | ||
bd371182 | 1777 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
1778 | impl<T> Extend<T> for Vec<T> { |
1779 | #[inline] | |
54a0048b | 1780 | fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I) { |
cc61c64b | 1781 | <Self as SpecExtend<T, I::IntoIter>>::spec_extend(self, iter.into_iter()) |
62682a34 SL |
1782 | } |
1783 | } | |
1784 | ||
476ff2be SL |
1785 | // Specialization trait used for Vec::from_iter and Vec::extend |
1786 | trait SpecExtend<T, I> { | |
1787 | fn from_iter(iter: I) -> Self; | |
1788 | fn spec_extend(&mut self, iter: I); | |
c30ab7b3 | 1789 | } |
c30ab7b3 | 1790 | |
476ff2be SL |
1791 | impl<T, I> SpecExtend<T, I> for Vec<T> |
1792 | where I: Iterator<Item=T>, | |
c30ab7b3 | 1793 | { |
476ff2be SL |
1794 | default fn from_iter(mut iterator: I) -> Self { |
1795 | // Unroll the first iteration, as the vector is going to be | |
1796 | // expanded on this iteration in every case when the iterable is not | |
1797 | // empty, but the loop in extend_desugared() is not going to see the | |
1798 | // vector being full in the few subsequent loop iterations. | |
1799 | // So we get better branch prediction. | |
1800 | let mut vector = match iterator.next() { | |
1801 | None => return Vec::new(), | |
1802 | Some(element) => { | |
1803 | let (lower, _) = iterator.size_hint(); | |
1804 | let mut vector = Vec::with_capacity(lower.saturating_add(1)); | |
1805 | unsafe { | |
1806 | ptr::write(vector.get_unchecked_mut(0), element); | |
1807 | vector.set_len(1); | |
1808 | } | |
1809 | vector | |
1810 | } | |
1811 | }; | |
cc61c64b | 1812 | <Vec<T> as SpecExtend<T, I>>::spec_extend(&mut vector, iterator); |
476ff2be SL |
1813 | vector |
1814 | } | |
1815 | ||
1816 | default fn spec_extend(&mut self, iter: I) { | |
1817 | self.extend_desugared(iter) | |
1818 | } | |
1819 | } | |
1820 | ||
1821 | impl<T, I> SpecExtend<T, I> for Vec<T> | |
1822 | where I: TrustedLen<Item=T>, | |
1823 | { | |
cc61c64b | 1824 | default fn from_iter(iterator: I) -> Self { |
476ff2be SL |
1825 | let mut vector = Vec::new(); |
1826 | vector.spec_extend(iterator); | |
1827 | vector | |
1828 | } | |
1829 | ||
cc61c64b | 1830 | default fn spec_extend(&mut self, iterator: I) { |
476ff2be SL |
1831 | // This is the case for a TrustedLen iterator. |
1832 | let (low, high) = iterator.size_hint(); | |
c30ab7b3 SL |
1833 | if let Some(high_value) = high { |
1834 | debug_assert_eq!(low, high_value, | |
1835 | "TrustedLen iterator's size hint is not exact: {:?}", | |
1836 | (low, high)); | |
1837 | } | |
476ff2be | 1838 | if let Some(additional) = high { |
c30ab7b3 | 1839 | self.reserve(additional); |
62682a34 | 1840 | unsafe { |
c30ab7b3 SL |
1841 | let mut ptr = self.as_mut_ptr().offset(self.len() as isize); |
1842 | let mut local_len = SetLenOnDrop::new(&mut self.len); | |
1843 | for element in iterator { | |
1844 | ptr::write(ptr, element); | |
1845 | ptr = ptr.offset(1); | |
1846 | // NB can't overflow since we would have had to alloc the address space | |
1847 | local_len.increment_len(1); | |
1848 | } | |
1849 | } | |
1850 | } else { | |
476ff2be SL |
1851 | self.extend_desugared(iterator) |
1852 | } | |
1853 | } | |
1854 | } | |
1855 | ||
cc61c64b XL |
1856 | impl<T> SpecExtend<T, IntoIter<T>> for Vec<T> { |
1857 | fn from_iter(iterator: IntoIter<T>) -> Self { | |
1858 | // A common case is passing a vector into a function which immediately | |
1859 | // re-collects into a vector. We can short circuit this if the IntoIter | |
1860 | // has not been advanced at all. | |
7cac9316 | 1861 | if iterator.buf.as_ptr() as *const _ == iterator.ptr { |
cc61c64b | 1862 | unsafe { |
7cac9316 | 1863 | let vec = Vec::from_raw_parts(iterator.buf.as_ptr(), |
cc61c64b XL |
1864 | iterator.len(), |
1865 | iterator.cap); | |
1866 | mem::forget(iterator); | |
1867 | vec | |
1868 | } | |
1869 | } else { | |
1870 | let mut vector = Vec::new(); | |
1871 | vector.spec_extend(iterator); | |
1872 | vector | |
1873 | } | |
1874 | } | |
1875 | ||
1876 | fn spec_extend(&mut self, mut iterator: IntoIter<T>) { | |
1877 | unsafe { | |
1878 | self.append_elements(iterator.as_slice() as _); | |
1879 | } | |
1880 | iterator.ptr = iterator.end; | |
1881 | } | |
1882 | } | |
1883 | ||
476ff2be SL |
1884 | impl<'a, T: 'a, I> SpecExtend<&'a T, I> for Vec<T> |
1885 | where I: Iterator<Item=&'a T>, | |
1886 | T: Clone, | |
1887 | { | |
1888 | default fn from_iter(iterator: I) -> Self { | |
1889 | SpecExtend::from_iter(iterator.cloned()) | |
1890 | } | |
1891 | ||
1892 | default fn spec_extend(&mut self, iterator: I) { | |
1893 | self.spec_extend(iterator.cloned()) | |
1894 | } | |
1895 | } | |
1896 | ||
1897 | impl<'a, T: 'a> SpecExtend<&'a T, slice::Iter<'a, T>> for Vec<T> | |
1898 | where T: Copy, | |
1899 | { | |
1900 | fn spec_extend(&mut self, iterator: slice::Iter<'a, T>) { | |
1901 | let slice = iterator.as_slice(); | |
1902 | self.reserve(slice.len()); | |
1903 | unsafe { | |
1904 | let len = self.len(); | |
1905 | self.set_len(len + slice.len()); | |
1906 | self.get_unchecked_mut(len..).copy_from_slice(slice); | |
1907 | } | |
1908 | } | |
1909 | } | |
1910 | ||
1911 | impl<T> Vec<T> { | |
1912 | fn extend_desugared<I: Iterator<Item = T>>(&mut self, mut iterator: I) { | |
1913 | // This is the case for a general iterator. | |
1914 | // | |
1915 | // This function should be the moral equivalent of: | |
1916 | // | |
1917 | // for item in iterator { | |
1918 | // self.push(item); | |
1919 | // } | |
1920 | while let Some(element) = iterator.next() { | |
1921 | let len = self.len(); | |
1922 | if len == self.capacity() { | |
1923 | let (lower, _) = iterator.size_hint(); | |
1924 | self.reserve(lower.saturating_add(1)); | |
1925 | } | |
1926 | unsafe { | |
1927 | ptr::write(self.get_unchecked_mut(len), element); | |
1928 | // NB can't overflow since we would have had to alloc the address space | |
1929 | self.set_len(len + 1); | |
62682a34 | 1930 | } |
1a4d82fc JJ |
1931 | } |
1932 | } | |
7cac9316 XL |
1933 | |
1934 | /// Creates a splicing iterator that replaces the specified range in the vector | |
1935 | /// with the given `replace_with` iterator and yields the removed items. | |
1936 | /// `replace_with` does not need to be the same length as `range`. | |
1937 | /// | |
1938 | /// Note 1: The element range is removed even if the iterator is not | |
1939 | /// consumed until the end. | |
1940 | /// | |
1941 | /// Note 2: It is unspecified how many elements are removed from the vector, | |
1942 | /// if the `Splice` value is leaked. | |
1943 | /// | |
1944 | /// Note 3: The input iterator `replace_with` is only consumed | |
1945 | /// when the `Splice` value is dropped. | |
1946 | /// | |
1947 | /// Note 4: This is optimal if: | |
1948 | /// | |
1949 | /// * The tail (elements in the vector after `range`) is empty, | |
1950 | /// * or `replace_with` yields fewer elements than `range`’s length | |
1951 | /// * or the lower bound of its `size_hint()` is exact. | |
1952 | /// | |
1953 | /// Otherwise, a temporary vector is allocated and the tail is moved twice. | |
1954 | /// | |
1955 | /// # Panics | |
1956 | /// | |
1957 | /// Panics if the starting point is greater than the end point or if | |
1958 | /// the end point is greater than the length of the vector. | |
1959 | /// | |
1960 | /// # Examples | |
1961 | /// | |
1962 | /// ``` | |
7cac9316 XL |
1963 | /// let mut v = vec![1, 2, 3]; |
1964 | /// let new = [7, 8]; | |
1965 | /// let u: Vec<_> = v.splice(..2, new.iter().cloned()).collect(); | |
1966 | /// assert_eq!(v, &[7, 8, 3]); | |
1967 | /// assert_eq!(u, &[1, 2]); | |
1968 | /// ``` | |
1969 | #[inline] | |
3b2f2976 | 1970 | #[stable(feature = "vec_splice", since = "1.21.0")] |
7cac9316 XL |
1971 | pub fn splice<R, I>(&mut self, range: R, replace_with: I) -> Splice<I::IntoIter> |
1972 | where R: RangeArgument<usize>, I: IntoIterator<Item=T> | |
1973 | { | |
1974 | Splice { | |
1975 | drain: self.drain(range), | |
1976 | replace_with: replace_with.into_iter(), | |
1977 | } | |
1978 | } | |
1979 | ||
3b2f2976 XL |
1980 | /// Creates an iterator which uses a closure to determine if an element should be removed. |
1981 | /// | |
1982 | /// If the closure returns true, then the element is removed and yielded. | |
1983 | /// If the closure returns false, it will try again, and call the closure | |
1984 | /// on the next element, seeing if it passes the test. | |
1985 | /// | |
1986 | /// Using this method is equivalent to the following code: | |
1987 | /// | |
1988 | /// ``` | |
ea8adc8c XL |
1989 | /// # let some_predicate = |x: &mut i32| { *x == 2 || *x == 3 || *x == 6 }; |
1990 | /// # let mut vec = vec![1, 2, 3, 4, 5, 6]; | |
3b2f2976 XL |
1991 | /// let mut i = 0; |
1992 | /// while i != vec.len() { | |
1993 | /// if some_predicate(&mut vec[i]) { | |
1994 | /// let val = vec.remove(i); | |
1995 | /// // your code here | |
ea8adc8c XL |
1996 | /// } else { |
1997 | /// i += 1; | |
3b2f2976 | 1998 | /// } |
3b2f2976 | 1999 | /// } |
ea8adc8c XL |
2000 | /// |
2001 | /// # assert_eq!(vec, vec![1, 4, 5]); | |
3b2f2976 XL |
2002 | /// ``` |
2003 | /// | |
2004 | /// But `drain_filter` is easier to use. `drain_filter` is also more efficient, | |
2005 | /// because it can backshift the elements of the array in bulk. | |
2006 | /// | |
2007 | /// Note that `drain_filter` also lets you mutate every element in the filter closure, | |
2008 | /// regardless of whether you choose to keep or remove it. | |
2009 | /// | |
2010 | /// | |
2011 | /// # Examples | |
2012 | /// | |
2013 | /// Splitting an array into evens and odds, reusing the original allocation: | |
2014 | /// | |
2015 | /// ``` | |
2016 | /// #![feature(drain_filter)] | |
2017 | /// let mut numbers = vec![1, 2, 3, 4, 5, 6, 8, 9, 11, 13, 14, 15]; | |
2018 | /// | |
2019 | /// let evens = numbers.drain_filter(|x| *x % 2 == 0).collect::<Vec<_>>(); | |
2020 | /// let odds = numbers; | |
2021 | /// | |
2022 | /// assert_eq!(evens, vec![2, 4, 6, 8, 14]); | |
2023 | /// assert_eq!(odds, vec![1, 3, 5, 9, 11, 13, 15]); | |
2024 | /// ``` | |
2025 | #[unstable(feature = "drain_filter", reason = "recently added", issue = "43244")] | |
2026 | pub fn drain_filter<F>(&mut self, filter: F) -> DrainFilter<T, F> | |
2027 | where F: FnMut(&mut T) -> bool, | |
2028 | { | |
2029 | let old_len = self.len(); | |
2030 | ||
2031 | // Guard against us getting leaked (leak amplification) | |
2032 | unsafe { self.set_len(0); } | |
2033 | ||
2034 | DrainFilter { | |
2035 | vec: self, | |
2036 | idx: 0, | |
2037 | del: 0, | |
2038 | old_len, | |
2039 | pred: filter, | |
2040 | } | |
2041 | } | |
1a4d82fc JJ |
2042 | } |
2043 | ||
3b2f2976 XL |
2044 | /// Extend implementation that copies elements out of references before pushing them onto the Vec. |
2045 | /// | |
2046 | /// This implementation is specialized for slice iterators, where it uses [`copy_from_slice`] to | |
2047 | /// append the entire slice at once. | |
2048 | /// | |
2049 | /// [`copy_from_slice`]: ../../std/primitive.slice.html#method.copy_from_slice | |
62682a34 SL |
2050 | #[stable(feature = "extend_ref", since = "1.2.0")] |
2051 | impl<'a, T: 'a + Copy> Extend<&'a T> for Vec<T> { | |
92a42be0 | 2052 | fn extend<I: IntoIterator<Item = &'a T>>(&mut self, iter: I) { |
476ff2be | 2053 | self.spec_extend(iter.into_iter()) |
62682a34 SL |
2054 | } |
2055 | } | |
2056 | ||
92a42be0 SL |
2057 | macro_rules! __impl_slice_eq1 { |
2058 | ($Lhs: ty, $Rhs: ty) => { | |
2059 | __impl_slice_eq1! { $Lhs, $Rhs, Sized } | |
2060 | }; | |
2061 | ($Lhs: ty, $Rhs: ty, $Bound: ident) => { | |
2062 | #[stable(feature = "rust1", since = "1.0.0")] | |
2063 | impl<'a, 'b, A: $Bound, B> PartialEq<$Rhs> for $Lhs where A: PartialEq<B> { | |
2064 | #[inline] | |
2065 | fn eq(&self, other: &$Rhs) -> bool { self[..] == other[..] } | |
2066 | #[inline] | |
2067 | fn ne(&self, other: &$Rhs) -> bool { self[..] != other[..] } | |
2068 | } | |
2069 | } | |
2070 | } | |
2071 | ||
c34b1796 AL |
2072 | __impl_slice_eq1! { Vec<A>, Vec<B> } |
2073 | __impl_slice_eq1! { Vec<A>, &'b [B] } | |
2074 | __impl_slice_eq1! { Vec<A>, &'b mut [B] } | |
2075 | __impl_slice_eq1! { Cow<'a, [A]>, &'b [B], Clone } | |
2076 | __impl_slice_eq1! { Cow<'a, [A]>, &'b mut [B], Clone } | |
2077 | __impl_slice_eq1! { Cow<'a, [A]>, Vec<B>, Clone } | |
2078 | ||
2079 | macro_rules! array_impls { | |
2080 | ($($N: expr)+) => { | |
2081 | $( | |
2082 | // NOTE: some less important impls are omitted to reduce code bloat | |
2083 | __impl_slice_eq1! { Vec<A>, [B; $N] } | |
2084 | __impl_slice_eq1! { Vec<A>, &'b [B; $N] } | |
2085 | // __impl_slice_eq1! { Vec<A>, &'b mut [B; $N] } | |
2086 | // __impl_slice_eq1! { Cow<'a, [A]>, [B; $N], Clone } | |
2087 | // __impl_slice_eq1! { Cow<'a, [A]>, &'b [B; $N], Clone } | |
2088 | // __impl_slice_eq1! { Cow<'a, [A]>, &'b mut [B; $N], Clone } | |
2089 | )+ | |
1a4d82fc JJ |
2090 | } |
2091 | } | |
2092 | ||
c34b1796 AL |
2093 | array_impls! { |
2094 | 0 1 2 3 4 5 6 7 8 9 | |
2095 | 10 11 12 13 14 15 16 17 18 19 | |
2096 | 20 21 22 23 24 25 26 27 28 29 | |
2097 | 30 31 32 | |
1a4d82fc JJ |
2098 | } |
2099 | ||
8bb4bdeb | 2100 | /// Implements comparison of vectors, lexicographically. |
85aaf69f | 2101 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
2102 | impl<T: PartialOrd> PartialOrd for Vec<T> { |
2103 | #[inline] | |
2104 | fn partial_cmp(&self, other: &Vec<T>) -> Option<Ordering> { | |
85aaf69f | 2105 | PartialOrd::partial_cmp(&**self, &**other) |
1a4d82fc JJ |
2106 | } |
2107 | } | |
2108 | ||
85aaf69f | 2109 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
2110 | impl<T: Eq> Eq for Vec<T> {} |
2111 | ||
8bb4bdeb | 2112 | /// Implements ordering of vectors, lexicographically. |
85aaf69f | 2113 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
2114 | impl<T: Ord> Ord for Vec<T> { |
2115 | #[inline] | |
2116 | fn cmp(&self, other: &Vec<T>) -> Ordering { | |
85aaf69f | 2117 | Ord::cmp(&**self, &**other) |
1a4d82fc JJ |
2118 | } |
2119 | } | |
2120 | ||
85aaf69f | 2121 | #[stable(feature = "rust1", since = "1.0.0")] |
32a655c1 | 2122 | unsafe impl<#[may_dangle] T> Drop for Vec<T> { |
1a4d82fc | 2123 | fn drop(&mut self) { |
9e0c209e SL |
2124 | unsafe { |
2125 | // use drop for [T] | |
2126 | ptr::drop_in_place(&mut self[..]); | |
1a4d82fc | 2127 | } |
c1a9b12d | 2128 | // RawVec handles deallocation |
1a4d82fc JJ |
2129 | } |
2130 | } | |
2131 | ||
85aaf69f | 2132 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 2133 | impl<T> Default for Vec<T> { |
9e0c209e | 2134 | /// Creates an empty `Vec<T>`. |
1a4d82fc JJ |
2135 | fn default() -> Vec<T> { |
2136 | Vec::new() | |
2137 | } | |
2138 | } | |
2139 | ||
85aaf69f SL |
2140 | #[stable(feature = "rust1", since = "1.0.0")] |
2141 | impl<T: fmt::Debug> fmt::Debug for Vec<T> { | |
1a4d82fc | 2142 | fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
85aaf69f | 2143 | fmt::Debug::fmt(&**self, f) |
1a4d82fc JJ |
2144 | } |
2145 | } | |
2146 | ||
c34b1796 AL |
2147 | #[stable(feature = "rust1", since = "1.0.0")] |
2148 | impl<T> AsRef<Vec<T>> for Vec<T> { | |
2149 | fn as_ref(&self) -> &Vec<T> { | |
2150 | self | |
2151 | } | |
2152 | } | |
2153 | ||
b039eaaf SL |
2154 | #[stable(feature = "vec_as_mut", since = "1.5.0")] |
2155 | impl<T> AsMut<Vec<T>> for Vec<T> { | |
2156 | fn as_mut(&mut self) -> &mut Vec<T> { | |
2157 | self | |
2158 | } | |
2159 | } | |
2160 | ||
c34b1796 AL |
2161 | #[stable(feature = "rust1", since = "1.0.0")] |
2162 | impl<T> AsRef<[T]> for Vec<T> { | |
2163 | fn as_ref(&self) -> &[T] { | |
2164 | self | |
2165 | } | |
2166 | } | |
2167 | ||
b039eaaf SL |
2168 | #[stable(feature = "vec_as_mut", since = "1.5.0")] |
2169 | impl<T> AsMut<[T]> for Vec<T> { | |
2170 | fn as_mut(&mut self) -> &mut [T] { | |
2171 | self | |
2172 | } | |
2173 | } | |
2174 | ||
c34b1796 AL |
2175 | #[stable(feature = "rust1", since = "1.0.0")] |
2176 | impl<'a, T: Clone> From<&'a [T]> for Vec<T> { | |
2177 | #[cfg(not(test))] | |
2178 | fn from(s: &'a [T]) -> Vec<T> { | |
2179 | s.to_vec() | |
2180 | } | |
2181 | #[cfg(test)] | |
2182 | fn from(s: &'a [T]) -> Vec<T> { | |
2183 | ::slice::to_vec(s) | |
2184 | } | |
2185 | } | |
2186 | ||
7cac9316 XL |
2187 | #[stable(feature = "vec_from_mut", since = "1.19.0")] |
2188 | impl<'a, T: Clone> From<&'a mut [T]> for Vec<T> { | |
2189 | #[cfg(not(test))] | |
2190 | fn from(s: &'a mut [T]) -> Vec<T> { | |
2191 | s.to_vec() | |
2192 | } | |
2193 | #[cfg(test)] | |
2194 | fn from(s: &'a mut [T]) -> Vec<T> { | |
2195 | ::slice::to_vec(s) | |
2196 | } | |
2197 | } | |
2198 | ||
c30ab7b3 SL |
2199 | #[stable(feature = "vec_from_cow_slice", since = "1.14.0")] |
2200 | impl<'a, T> From<Cow<'a, [T]>> for Vec<T> where [T]: ToOwned<Owned=Vec<T>> { | |
2201 | fn from(s: Cow<'a, [T]>) -> Vec<T> { | |
2202 | s.into_owned() | |
2203 | } | |
2204 | } | |
2205 | ||
cc61c64b XL |
2206 | // note: test pulls in libstd, which causes errors here |
2207 | #[cfg(not(test))] | |
7cac9316 | 2208 | #[stable(feature = "vec_from_box", since = "1.18.0")] |
cc61c64b XL |
2209 | impl<T> From<Box<[T]>> for Vec<T> { |
2210 | fn from(s: Box<[T]>) -> Vec<T> { | |
2211 | s.into_vec() | |
2212 | } | |
2213 | } | |
2214 | ||
041b39d2 XL |
2215 | // note: test pulls in libstd, which causes errors here |
2216 | #[cfg(not(test))] | |
2217 | #[stable(feature = "box_from_vec", since = "1.20.0")] | |
2218 | impl<T> From<Vec<T>> for Box<[T]> { | |
2219 | fn from(v: Vec<T>) -> Box<[T]> { | |
2220 | v.into_boxed_slice() | |
cc61c64b XL |
2221 | } |
2222 | } | |
2223 | ||
c34b1796 AL |
2224 | #[stable(feature = "rust1", since = "1.0.0")] |
2225 | impl<'a> From<&'a str> for Vec<u8> { | |
2226 | fn from(s: &'a str) -> Vec<u8> { | |
2227 | From::from(s.as_bytes()) | |
2228 | } | |
2229 | } | |
2230 | ||
1a4d82fc JJ |
2231 | //////////////////////////////////////////////////////////////////////////////// |
2232 | // Clone-on-write | |
2233 | //////////////////////////////////////////////////////////////////////////////// | |
2234 | ||
7cac9316 | 2235 | #[stable(feature = "cow_from_vec", since = "1.8.0")] |
7453a54e SL |
2236 | impl<'a, T: Clone> From<&'a [T]> for Cow<'a, [T]> { |
2237 | fn from(s: &'a [T]) -> Cow<'a, [T]> { | |
2238 | Cow::Borrowed(s) | |
2239 | } | |
2240 | } | |
2241 | ||
7cac9316 | 2242 | #[stable(feature = "cow_from_vec", since = "1.8.0")] |
7453a54e SL |
2243 | impl<'a, T: Clone> From<Vec<T>> for Cow<'a, [T]> { |
2244 | fn from(v: Vec<T>) -> Cow<'a, [T]> { | |
2245 | Cow::Owned(v) | |
2246 | } | |
2247 | } | |
2248 | ||
bd371182 | 2249 | #[stable(feature = "rust1", since = "1.0.0")] |
85aaf69f | 2250 | impl<'a, T> FromIterator<T> for Cow<'a, [T]> where T: Clone { |
92a42be0 | 2251 | fn from_iter<I: IntoIterator<Item = T>>(it: I) -> Cow<'a, [T]> { |
1a4d82fc JJ |
2252 | Cow::Owned(FromIterator::from_iter(it)) |
2253 | } | |
2254 | } | |
2255 | ||
1a4d82fc JJ |
2256 | //////////////////////////////////////////////////////////////////////////////// |
2257 | // Iterators | |
2258 | //////////////////////////////////////////////////////////////////////////////// | |
2259 | ||
2260 | /// An iterator that moves out of a vector. | |
5bcae85e SL |
2261 | /// |
2262 | /// This `struct` is created by the `into_iter` method on [`Vec`][`Vec`] (provided | |
2263 | /// by the [`IntoIterator`] trait). | |
2264 | /// | |
2265 | /// [`Vec`]: struct.Vec.html | |
2266 | /// [`IntoIterator`]: ../../std/iter/trait.IntoIterator.html | |
85aaf69f | 2267 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc | 2268 | pub struct IntoIter<T> { |
5bcae85e SL |
2269 | buf: Shared<T>, |
2270 | cap: usize, | |
1a4d82fc | 2271 | ptr: *const T, |
92a42be0 | 2272 | end: *const T, |
1a4d82fc JJ |
2273 | } |
2274 | ||
c30ab7b3 | 2275 | #[stable(feature = "vec_intoiter_debug", since = "1.13.0")] |
9e0c209e SL |
2276 | impl<T: fmt::Debug> fmt::Debug for IntoIter<T> { |
2277 | fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { | |
2278 | f.debug_tuple("IntoIter") | |
2279 | .field(&self.as_slice()) | |
2280 | .finish() | |
2281 | } | |
2282 | } | |
2283 | ||
5bcae85e SL |
2284 | impl<T> IntoIter<T> { |
2285 | /// Returns the remaining items of this iterator as a slice. | |
2286 | /// | |
2287 | /// # Examples | |
2288 | /// | |
c30ab7b3 | 2289 | /// ``` |
5bcae85e SL |
2290 | /// let vec = vec!['a', 'b', 'c']; |
2291 | /// let mut into_iter = vec.into_iter(); | |
2292 | /// assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']); | |
2293 | /// let _ = into_iter.next().unwrap(); | |
2294 | /// assert_eq!(into_iter.as_slice(), &['b', 'c']); | |
2295 | /// ``` | |
476ff2be | 2296 | #[stable(feature = "vec_into_iter_as_slice", since = "1.15.0")] |
5bcae85e SL |
2297 | pub fn as_slice(&self) -> &[T] { |
2298 | unsafe { | |
2299 | slice::from_raw_parts(self.ptr, self.len()) | |
2300 | } | |
2301 | } | |
2302 | ||
2303 | /// Returns the remaining items of this iterator as a mutable slice. | |
2304 | /// | |
2305 | /// # Examples | |
2306 | /// | |
c30ab7b3 | 2307 | /// ``` |
5bcae85e SL |
2308 | /// let vec = vec!['a', 'b', 'c']; |
2309 | /// let mut into_iter = vec.into_iter(); | |
2310 | /// assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']); | |
2311 | /// into_iter.as_mut_slice()[2] = 'z'; | |
2312 | /// assert_eq!(into_iter.next().unwrap(), 'a'); | |
2313 | /// assert_eq!(into_iter.next().unwrap(), 'b'); | |
2314 | /// assert_eq!(into_iter.next().unwrap(), 'z'); | |
2315 | /// ``` | |
476ff2be | 2316 | #[stable(feature = "vec_into_iter_as_slice", since = "1.15.0")] |
e81b0574 | 2317 | pub fn as_mut_slice(&mut self) -> &mut [T] { |
5bcae85e SL |
2318 | unsafe { |
2319 | slice::from_raw_parts_mut(self.ptr as *mut T, self.len()) | |
2320 | } | |
2321 | } | |
2322 | } | |
2323 | ||
92a42be0 SL |
2324 | #[stable(feature = "rust1", since = "1.0.0")] |
2325 | unsafe impl<T: Send> Send for IntoIter<T> {} | |
2326 | #[stable(feature = "rust1", since = "1.0.0")] | |
2327 | unsafe impl<T: Sync> Sync for IntoIter<T> {} | |
85aaf69f | 2328 | |
85aaf69f | 2329 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
2330 | impl<T> Iterator for IntoIter<T> { |
2331 | type Item = T; | |
2332 | ||
2333 | #[inline] | |
85aaf69f | 2334 | fn next(&mut self) -> Option<T> { |
1a4d82fc | 2335 | unsafe { |
5bcae85e | 2336 | if self.ptr as *const _ == self.end { |
1a4d82fc JJ |
2337 | None |
2338 | } else { | |
2339 | if mem::size_of::<T>() == 0 { | |
2340 | // purposefully don't use 'ptr.offset' because for | |
2341 | // vectors with 0-size elements this would return the | |
2342 | // same pointer. | |
5bcae85e | 2343 | self.ptr = arith_offset(self.ptr as *const i8, 1) as *mut T; |
1a4d82fc JJ |
2344 | |
2345 | // Use a non-null pointer value | |
7cac9316 XL |
2346 | // (self.ptr might be null because of wrapping) |
2347 | Some(ptr::read(1 as *mut T)) | |
1a4d82fc JJ |
2348 | } else { |
2349 | let old = self.ptr; | |
2350 | self.ptr = self.ptr.offset(1); | |
2351 | ||
2352 | Some(ptr::read(old)) | |
2353 | } | |
2354 | } | |
2355 | } | |
2356 | } | |
2357 | ||
2358 | #[inline] | |
85aaf69f | 2359 | fn size_hint(&self) -> (usize, Option<usize>) { |
cc61c64b XL |
2360 | let exact = match self.ptr.offset_to(self.end) { |
2361 | Some(x) => x as usize, | |
2362 | None => (self.end as usize).wrapping_sub(self.ptr as usize), | |
2363 | }; | |
1a4d82fc JJ |
2364 | (exact, Some(exact)) |
2365 | } | |
d9579d0f AL |
2366 | |
2367 | #[inline] | |
2368 | fn count(self) -> usize { | |
3157f602 | 2369 | self.len() |
d9579d0f | 2370 | } |
1a4d82fc JJ |
2371 | } |
2372 | ||
85aaf69f | 2373 | #[stable(feature = "rust1", since = "1.0.0")] |
1a4d82fc JJ |
2374 | impl<T> DoubleEndedIterator for IntoIter<T> { |
2375 | #[inline] | |
85aaf69f | 2376 | fn next_back(&mut self) -> Option<T> { |
1a4d82fc JJ |
2377 | unsafe { |
2378 | if self.end == self.ptr { | |
2379 | None | |
2380 | } else { | |
2381 | if mem::size_of::<T>() == 0 { | |
2382 | // See above for why 'ptr.offset' isn't used | |
5bcae85e | 2383 | self.end = arith_offset(self.end as *const i8, -1) as *mut T; |
1a4d82fc JJ |
2384 | |
2385 | // Use a non-null pointer value | |
7cac9316 XL |
2386 | // (self.end might be null because of wrapping) |
2387 | Some(ptr::read(1 as *mut T)) | |
1a4d82fc JJ |
2388 | } else { |
2389 | self.end = self.end.offset(-1); | |
2390 | ||
e9174d1e | 2391 | Some(ptr::read(self.end)) |
1a4d82fc JJ |
2392 | } |
2393 | } | |
2394 | } | |
2395 | } | |
2396 | } | |
2397 | ||
85aaf69f | 2398 | #[stable(feature = "rust1", since = "1.0.0")] |
476ff2be SL |
2399 | impl<T> ExactSizeIterator for IntoIter<T> { |
2400 | fn is_empty(&self) -> bool { | |
2401 | self.ptr == self.end | |
2402 | } | |
2403 | } | |
1a4d82fc | 2404 | |
9e0c209e SL |
2405 | #[unstable(feature = "fused", issue = "35602")] |
2406 | impl<T> FusedIterator for IntoIter<T> {} | |
2407 | ||
c30ab7b3 SL |
2408 | #[unstable(feature = "trusted_len", issue = "37572")] |
2409 | unsafe impl<T> TrustedLen for IntoIter<T> {} | |
2410 | ||
7453a54e SL |
2411 | #[stable(feature = "vec_into_iter_clone", since = "1.8.0")] |
2412 | impl<T: Clone> Clone for IntoIter<T> { | |
2413 | fn clone(&self) -> IntoIter<T> { | |
5bcae85e | 2414 | self.as_slice().to_owned().into_iter() |
7453a54e SL |
2415 | } |
2416 | } | |
2417 | ||
85aaf69f | 2418 | #[stable(feature = "rust1", since = "1.0.0")] |
32a655c1 | 2419 | unsafe impl<#[may_dangle] T> Drop for IntoIter<T> { |
1a4d82fc JJ |
2420 | fn drop(&mut self) { |
2421 | // destroy the remaining elements | |
5bcae85e | 2422 | for _x in self.by_ref() {} |
c1a9b12d SL |
2423 | |
2424 | // RawVec handles deallocation | |
7cac9316 | 2425 | let _ = unsafe { RawVec::from_raw_parts(self.buf.as_ptr(), self.cap) }; |
1a4d82fc JJ |
2426 | } |
2427 | } | |
2428 | ||
d9579d0f | 2429 | /// A draining iterator for `Vec<T>`. |
5bcae85e SL |
2430 | /// |
2431 | /// This `struct` is created by the [`drain`] method on [`Vec`]. | |
2432 | /// | |
2433 | /// [`drain`]: struct.Vec.html#method.drain | |
2434 | /// [`Vec`]: struct.Vec.html | |
92a42be0 | 2435 | #[stable(feature = "drain", since = "1.6.0")] |
d9579d0f AL |
2436 | pub struct Drain<'a, T: 'a> { |
2437 | /// Index of tail to preserve | |
2438 | tail_start: usize, | |
2439 | /// Length of tail | |
2440 | tail_len: usize, | |
2441 | /// Current remaining range to remove | |
5bcae85e SL |
2442 | iter: slice::Iter<'a, T>, |
2443 | vec: Shared<Vec<T>>, | |
1a4d82fc JJ |
2444 | } |
2445 | ||
8bb4bdeb XL |
2446 | #[stable(feature = "collection_debug", since = "1.17.0")] |
2447 | impl<'a, T: 'a + fmt::Debug> fmt::Debug for Drain<'a, T> { | |
2448 | fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { | |
2449 | f.debug_tuple("Drain") | |
2450 | .field(&self.iter.as_slice()) | |
2451 | .finish() | |
2452 | } | |
2453 | } | |
2454 | ||
92a42be0 | 2455 | #[stable(feature = "drain", since = "1.6.0")] |
c34b1796 | 2456 | unsafe impl<'a, T: Sync> Sync for Drain<'a, T> {} |
92a42be0 | 2457 | #[stable(feature = "drain", since = "1.6.0")] |
c34b1796 AL |
2458 | unsafe impl<'a, T: Send> Send for Drain<'a, T> {} |
2459 | ||
c30ab7b3 | 2460 | #[stable(feature = "drain", since = "1.6.0")] |
1a4d82fc JJ |
2461 | impl<'a, T> Iterator for Drain<'a, T> { |
2462 | type Item = T; | |
2463 | ||
2464 | #[inline] | |
2465 | fn next(&mut self) -> Option<T> { | |
92a42be0 | 2466 | self.iter.next().map(|elt| unsafe { ptr::read(elt as *const _) }) |
1a4d82fc JJ |
2467 | } |
2468 | ||
85aaf69f | 2469 | fn size_hint(&self) -> (usize, Option<usize>) { |
d9579d0f | 2470 | self.iter.size_hint() |
1a4d82fc JJ |
2471 | } |
2472 | } | |
2473 | ||
c30ab7b3 | 2474 | #[stable(feature = "drain", since = "1.6.0")] |
1a4d82fc JJ |
2475 | impl<'a, T> DoubleEndedIterator for Drain<'a, T> { |
2476 | #[inline] | |
2477 | fn next_back(&mut self) -> Option<T> { | |
92a42be0 | 2478 | self.iter.next_back().map(|elt| unsafe { ptr::read(elt as *const _) }) |
1a4d82fc JJ |
2479 | } |
2480 | } | |
2481 | ||
c30ab7b3 | 2482 | #[stable(feature = "drain", since = "1.6.0")] |
1a4d82fc JJ |
2483 | impl<'a, T> Drop for Drain<'a, T> { |
2484 | fn drop(&mut self) { | |
d9579d0f | 2485 | // exhaust self first |
92a42be0 | 2486 | while let Some(_) = self.next() {} |
1a4d82fc | 2487 | |
d9579d0f AL |
2488 | if self.tail_len > 0 { |
2489 | unsafe { | |
7cac9316 | 2490 | let source_vec = self.vec.as_mut(); |
d9579d0f AL |
2491 | // memmove back untouched tail, update to new length |
2492 | let start = source_vec.len(); | |
2493 | let tail = self.tail_start; | |
2494 | let src = source_vec.as_ptr().offset(tail as isize); | |
2495 | let dst = source_vec.as_mut_ptr().offset(start as isize); | |
2496 | ptr::copy(src, dst, self.tail_len); | |
2497 | source_vec.set_len(start + self.tail_len); | |
2498 | } | |
2499 | } | |
1a4d82fc JJ |
2500 | } |
2501 | } | |
2502 | ||
d9579d0f | 2503 | |
c30ab7b3 | 2504 | #[stable(feature = "drain", since = "1.6.0")] |
476ff2be SL |
2505 | impl<'a, T> ExactSizeIterator for Drain<'a, T> { |
2506 | fn is_empty(&self) -> bool { | |
2507 | self.iter.is_empty() | |
2508 | } | |
2509 | } | |
9e0c209e SL |
2510 | |
2511 | #[unstable(feature = "fused", issue = "35602")] | |
2512 | impl<'a, T> FusedIterator for Drain<'a, T> {} | |
32a655c1 SL |
2513 | |
2514 | /// A place for insertion at the back of a `Vec`. | |
2515 | /// | |
2516 | /// See [`Vec::place_back`](struct.Vec.html#method.place_back) for details. | |
2517 | #[must_use = "places do nothing unless written to with `<-` syntax"] | |
2518 | #[unstable(feature = "collection_placement", | |
2519 | reason = "struct name and placement protocol are subject to change", | |
2520 | issue = "30172")] | |
8bb4bdeb | 2521 | #[derive(Debug)] |
32a655c1 SL |
2522 | pub struct PlaceBack<'a, T: 'a> { |
2523 | vec: &'a mut Vec<T>, | |
2524 | } | |
2525 | ||
2526 | #[unstable(feature = "collection_placement", | |
2527 | reason = "placement protocol is subject to change", | |
2528 | issue = "30172")] | |
2529 | impl<'a, T> Placer<T> for PlaceBack<'a, T> { | |
2530 | type Place = PlaceBack<'a, T>; | |
2531 | ||
2532 | fn make_place(self) -> Self { | |
2533 | // This will panic or abort if we would allocate > isize::MAX bytes | |
2534 | // or if the length increment would overflow for zero-sized types. | |
2535 | if self.vec.len == self.vec.buf.cap() { | |
2536 | self.vec.buf.double(); | |
2537 | } | |
2538 | self | |
2539 | } | |
2540 | } | |
2541 | ||
2542 | #[unstable(feature = "collection_placement", | |
2543 | reason = "placement protocol is subject to change", | |
2544 | issue = "30172")] | |
2545 | impl<'a, T> Place<T> for PlaceBack<'a, T> { | |
2546 | fn pointer(&mut self) -> *mut T { | |
2547 | unsafe { self.vec.as_mut_ptr().offset(self.vec.len as isize) } | |
2548 | } | |
2549 | } | |
2550 | ||
2551 | #[unstable(feature = "collection_placement", | |
2552 | reason = "placement protocol is subject to change", | |
2553 | issue = "30172")] | |
2554 | impl<'a, T> InPlace<T> for PlaceBack<'a, T> { | |
2555 | type Owner = &'a mut T; | |
2556 | ||
2557 | unsafe fn finalize(mut self) -> &'a mut T { | |
2558 | let ptr = self.pointer(); | |
2559 | self.vec.len += 1; | |
2560 | &mut *ptr | |
2561 | } | |
2562 | } | |
7cac9316 XL |
2563 | |
2564 | ||
2565 | /// A splicing iterator for `Vec`. | |
2566 | /// | |
2567 | /// This struct is created by the [`splice()`] method on [`Vec`]. See its | |
2568 | /// documentation for more. | |
2569 | /// | |
2570 | /// [`splice()`]: struct.Vec.html#method.splice | |
2571 | /// [`Vec`]: struct.Vec.html | |
2572 | #[derive(Debug)] | |
3b2f2976 | 2573 | #[stable(feature = "vec_splice", since = "1.21.0")] |
7cac9316 XL |
2574 | pub struct Splice<'a, I: Iterator + 'a> { |
2575 | drain: Drain<'a, I::Item>, | |
2576 | replace_with: I, | |
2577 | } | |
2578 | ||
3b2f2976 | 2579 | #[stable(feature = "vec_splice", since = "1.21.0")] |
7cac9316 XL |
2580 | impl<'a, I: Iterator> Iterator for Splice<'a, I> { |
2581 | type Item = I::Item; | |
2582 | ||
2583 | fn next(&mut self) -> Option<Self::Item> { | |
2584 | self.drain.next() | |
2585 | } | |
2586 | ||
2587 | fn size_hint(&self) -> (usize, Option<usize>) { | |
2588 | self.drain.size_hint() | |
2589 | } | |
2590 | } | |
2591 | ||
3b2f2976 | 2592 | #[stable(feature = "vec_splice", since = "1.21.0")] |
7cac9316 XL |
2593 | impl<'a, I: Iterator> DoubleEndedIterator for Splice<'a, I> { |
2594 | fn next_back(&mut self) -> Option<Self::Item> { | |
2595 | self.drain.next_back() | |
2596 | } | |
2597 | } | |
2598 | ||
3b2f2976 | 2599 | #[stable(feature = "vec_splice", since = "1.21.0")] |
7cac9316 XL |
2600 | impl<'a, I: Iterator> ExactSizeIterator for Splice<'a, I> {} |
2601 | ||
2602 | ||
3b2f2976 | 2603 | #[stable(feature = "vec_splice", since = "1.21.0")] |
7cac9316 XL |
2604 | impl<'a, I: Iterator> Drop for Splice<'a, I> { |
2605 | fn drop(&mut self) { | |
2606 | // exhaust drain first | |
2607 | while let Some(_) = self.drain.next() {} | |
2608 | ||
2609 | ||
2610 | unsafe { | |
2611 | if self.drain.tail_len == 0 { | |
2612 | self.drain.vec.as_mut().extend(self.replace_with.by_ref()); | |
2613 | return | |
2614 | } | |
2615 | ||
2616 | // First fill the range left by drain(). | |
2617 | if !self.drain.fill(&mut self.replace_with) { | |
2618 | return | |
2619 | } | |
2620 | ||
2621 | // There may be more elements. Use the lower bound as an estimate. | |
2622 | // FIXME: Is the upper bound a better guess? Or something else? | |
2623 | let (lower_bound, _upper_bound) = self.replace_with.size_hint(); | |
2624 | if lower_bound > 0 { | |
2625 | self.drain.move_tail(lower_bound); | |
2626 | if !self.drain.fill(&mut self.replace_with) { | |
2627 | return | |
2628 | } | |
2629 | } | |
2630 | ||
2631 | // Collect any remaining elements. | |
2632 | // This is a zero-length vector which does not allocate if `lower_bound` was exact. | |
2633 | let mut collected = self.replace_with.by_ref().collect::<Vec<I::Item>>().into_iter(); | |
2634 | // Now we have an exact count. | |
2635 | if collected.len() > 0 { | |
2636 | self.drain.move_tail(collected.len()); | |
2637 | let filled = self.drain.fill(&mut collected); | |
2638 | debug_assert!(filled); | |
2639 | debug_assert_eq!(collected.len(), 0); | |
2640 | } | |
2641 | } | |
2642 | // Let `Drain::drop` move the tail back if necessary and restore `vec.len`. | |
2643 | } | |
2644 | } | |
2645 | ||
2646 | /// Private helper methods for `Splice::drop` | |
2647 | impl<'a, T> Drain<'a, T> { | |
2648 | /// The range from `self.vec.len` to `self.tail_start` contains elements | |
2649 | /// that have been moved out. | |
2650 | /// Fill that range as much as possible with new elements from the `replace_with` iterator. | |
2651 | /// Return whether we filled the entire range. (`replace_with.next()` didn’t return `None`.) | |
2652 | unsafe fn fill<I: Iterator<Item=T>>(&mut self, replace_with: &mut I) -> bool { | |
2653 | let vec = self.vec.as_mut(); | |
2654 | let range_start = vec.len; | |
2655 | let range_end = self.tail_start; | |
2656 | let range_slice = slice::from_raw_parts_mut( | |
2657 | vec.as_mut_ptr().offset(range_start as isize), | |
2658 | range_end - range_start); | |
2659 | ||
2660 | for place in range_slice { | |
2661 | if let Some(new_item) = replace_with.next() { | |
2662 | ptr::write(place, new_item); | |
2663 | vec.len += 1; | |
2664 | } else { | |
2665 | return false | |
2666 | } | |
2667 | } | |
2668 | true | |
2669 | } | |
2670 | ||
2671 | /// Make room for inserting more elements before the tail. | |
2672 | unsafe fn move_tail(&mut self, extra_capacity: usize) { | |
2673 | let vec = self.vec.as_mut(); | |
2674 | let used_capacity = self.tail_start + self.tail_len; | |
2675 | vec.buf.reserve(used_capacity, extra_capacity); | |
2676 | ||
2677 | let new_tail_start = self.tail_start + extra_capacity; | |
2678 | let src = vec.as_ptr().offset(self.tail_start as isize); | |
2679 | let dst = vec.as_mut_ptr().offset(new_tail_start as isize); | |
2680 | ptr::copy(src, dst, self.tail_len); | |
2681 | self.tail_start = new_tail_start; | |
2682 | } | |
2683 | } | |
3b2f2976 XL |
2684 | |
2685 | /// An iterator produced by calling `drain_filter` on Vec. | |
2686 | #[unstable(feature = "drain_filter", reason = "recently added", issue = "43244")] | |
2687 | #[derive(Debug)] | |
2688 | pub struct DrainFilter<'a, T: 'a, F> | |
2689 | where F: FnMut(&mut T) -> bool, | |
2690 | { | |
2691 | vec: &'a mut Vec<T>, | |
2692 | idx: usize, | |
2693 | del: usize, | |
2694 | old_len: usize, | |
2695 | pred: F, | |
2696 | } | |
2697 | ||
2698 | #[unstable(feature = "drain_filter", reason = "recently added", issue = "43244")] | |
2699 | impl<'a, T, F> Iterator for DrainFilter<'a, T, F> | |
2700 | where F: FnMut(&mut T) -> bool, | |
2701 | { | |
2702 | type Item = T; | |
2703 | ||
2704 | fn next(&mut self) -> Option<T> { | |
2705 | unsafe { | |
2706 | while self.idx != self.old_len { | |
2707 | let i = self.idx; | |
2708 | self.idx += 1; | |
2709 | let v = slice::from_raw_parts_mut(self.vec.as_mut_ptr(), self.old_len); | |
2710 | if (self.pred)(&mut v[i]) { | |
2711 | self.del += 1; | |
2712 | return Some(ptr::read(&v[i])); | |
2713 | } else if self.del > 0 { | |
ea8adc8c XL |
2714 | let del = self.del; |
2715 | let src: *const T = &v[i]; | |
2716 | let dst: *mut T = &mut v[i - del]; | |
2717 | // This is safe because self.vec has length 0 | |
2718 | // thus its elements will not have Drop::drop | |
2719 | // called on them in the event of a panic. | |
2720 | ptr::copy_nonoverlapping(src, dst, 1); | |
3b2f2976 XL |
2721 | } |
2722 | } | |
2723 | None | |
2724 | } | |
2725 | } | |
2726 | ||
2727 | fn size_hint(&self) -> (usize, Option<usize>) { | |
2728 | (0, Some(self.old_len - self.idx)) | |
2729 | } | |
2730 | } | |
2731 | ||
2732 | #[unstable(feature = "drain_filter", reason = "recently added", issue = "43244")] | |
2733 | impl<'a, T, F> Drop for DrainFilter<'a, T, F> | |
2734 | where F: FnMut(&mut T) -> bool, | |
2735 | { | |
2736 | fn drop(&mut self) { | |
2737 | for _ in self.by_ref() { } | |
2738 | ||
2739 | unsafe { | |
2740 | self.vec.set_len(self.old_len - self.del); | |
2741 | } | |
2742 | } | |
2743 | } |