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.
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.
11 //! A contiguous growable array type with heap-allocated contents, written
12 //! `Vec<T>` but pronounced 'vector.'
14 //! Vectors have `O(1)` indexing, amortized `O(1)` push (to the end) and
15 //! `O(1)` pop (from the end).
19 //! You can explicitly create a [`Vec<T>`] with [`new()`]:
22 //! let v: Vec<i32> = Vec::new();
25 //! ...or by using the [`vec!`] macro:
28 //! let v: Vec<i32> = vec![];
30 //! let v = vec![1, 2, 3, 4, 5];
32 //! let v = vec![0; 10]; // ten zeroes
35 //! You can [`push`] values onto the end of a vector (which will grow the vector
39 //! let mut v = vec![1, 2];
44 //! Popping values works in much the same way:
47 //! let mut v = vec![1, 2];
49 //! let two = v.pop();
52 //! Vectors also support indexing (through the [`Index`] and [`IndexMut`] traits):
55 //! let mut v = vec![1, 2, 3];
60 //! [`Vec<T>`]: ../../std/vec/struct.Vec.html
61 //! [`new()`]: ../../std/vec/struct.Vec.html#method.new
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
67 #![stable(feature = "rust1", since = "1.0.0")]
69 use alloc
::boxed
::Box
;
70 use alloc
::heap
::EMPTY
;
71 use alloc
::raw_vec
::RawVec
;
74 use core
::cmp
::Ordering
;
76 use core
::hash
::{self, Hash}
;
77 use core
::intrinsics
::{arith_offset, assume}
;
78 use core
::iter
::{FromIterator, FusedIterator, TrustedLen}
;
80 use core
::ops
::{Index, IndexMut}
;
83 use core
::ptr
::Shared
;
86 use super::range
::RangeArgument
;
88 /// A contiguous growable array type, written `Vec<T>` but pronounced 'vector'.
93 /// let mut vec = Vec::new();
97 /// assert_eq!(vec.len(), 2);
98 /// assert_eq!(vec[0], 1);
100 /// assert_eq!(vec.pop(), Some(2));
101 /// assert_eq!(vec.len(), 1);
104 /// assert_eq!(vec[0], 7);
106 /// vec.extend([1, 2, 3].iter().cloned());
109 /// println!("{}", x);
111 /// assert_eq!(vec, [7, 1, 2, 3]);
114 /// The [`vec!`] macro is provided to make initialization more convenient:
117 /// let mut vec = vec![1, 2, 3];
119 /// assert_eq!(vec, [1, 2, 3, 4]);
122 /// It can also initialize each element of a `Vec<T>` with a given value:
125 /// let vec = vec![0; 5];
126 /// assert_eq!(vec, [0, 0, 0, 0, 0]);
129 /// Use a `Vec<T>` as an efficient stack:
132 /// let mut stack = Vec::new();
138 /// while let Some(top) = stack.pop() {
139 /// // Prints 3, 2, 1
140 /// println!("{}", top);
146 /// The `Vec` type allows to access values by index, because it implements the
147 /// [`Index`] trait. An example will be more explicit:
150 /// let v = vec![0, 2, 4, 6];
151 /// println!("{}", v[1]); // it will display '2'
154 /// However be careful: if you try to access an index which isn't in the `Vec`,
155 /// your software will panic! You cannot do this:
158 /// let v = vec![0, 2, 4, 6];
159 /// println!("{}", v[6]); // it will panic!
162 /// In conclusion: always check if the index you want to get really exists
167 /// A `Vec` can be mutable. Slices, on the other hand, are read-only objects.
168 /// To get a slice, use `&`. Example:
171 /// fn read_slice(slice: &[usize]) {
175 /// let v = vec![0, 1];
178 /// // ... and that's all!
179 /// // you can also do it like this:
180 /// let x : &[usize] = &v;
183 /// In Rust, it's more common to pass slices as arguments rather than vectors
184 /// when you just want to provide a read access. The same goes for [`String`] and
187 /// # Capacity and reallocation
189 /// The capacity of a vector is the amount of space allocated for any future
190 /// elements that will be added onto the vector. This is not to be confused with
191 /// the *length* of a vector, which specifies the number of actual elements
192 /// within the vector. If a vector's length exceeds its capacity, its capacity
193 /// will automatically be increased, but its elements will have to be
196 /// For example, a vector with capacity 10 and length 0 would be an empty vector
197 /// with space for 10 more elements. Pushing 10 or fewer elements onto the
198 /// vector will not change its capacity or cause reallocation to occur. However,
199 /// if the vector's length is increased to 11, it will have to reallocate, which
200 /// can be slow. For this reason, it is recommended to use [`Vec::with_capacity`]
201 /// whenever possible to specify how big the vector is expected to get.
205 /// Due to its incredibly fundamental nature, `Vec` makes a lot of guarantees
206 /// about its design. This ensures that it's as low-overhead as possible in
207 /// the general case, and can be correctly manipulated in primitive ways
208 /// by unsafe code. Note that these guarantees refer to an unqualified `Vec<T>`.
209 /// If additional type parameters are added (e.g. to support custom allocators),
210 /// overriding their defaults may change the behavior.
212 /// Most fundamentally, `Vec` is and always will be a (pointer, capacity, length)
213 /// triplet. No more, no less. The order of these fields is completely
214 /// unspecified, and you should use the appropriate methods to modify these.
215 /// The pointer will never be null, so this type is null-pointer-optimized.
217 /// However, the pointer may not actually point to allocated memory. In particular,
218 /// if you construct a `Vec` with capacity 0 via [`Vec::new()`], [`vec![]`][`vec!`],
219 /// [`Vec::with_capacity(0)`][`Vec::with_capacity`], or by calling [`shrink_to_fit()`]
220 /// on an empty Vec, it will not allocate memory. Similarly, if you store zero-sized
221 /// types inside a `Vec`, it will not allocate space for them. *Note that in this case
222 /// the `Vec` may not report a [`capacity()`] of 0*. `Vec` will allocate if and only
223 /// if [`mem::size_of::<T>()`]` * capacity() > 0`. In general, `Vec`'s allocation
224 /// details are subtle enough that it is strongly recommended that you only
225 /// free memory allocated by a `Vec` by creating a new `Vec` and dropping it.
227 /// If a `Vec` *has* allocated memory, then the memory it points to is on the heap
228 /// (as defined by the allocator Rust is configured to use by default), and its
229 /// pointer points to [`len()`] initialized elements in order (what you would see
230 /// if you coerced it to a slice), followed by [`capacity()`]` - `[`len()`]
231 /// logically uninitialized elements.
233 /// `Vec` will never perform a "small optimization" where elements are actually
234 /// stored on the stack for two reasons:
236 /// * It would make it more difficult for unsafe code to correctly manipulate
237 /// a `Vec`. The contents of a `Vec` wouldn't have a stable address if it were
238 /// only moved, and it would be more difficult to determine if a `Vec` had
239 /// actually allocated memory.
241 /// * It would penalize the general case, incurring an additional branch
244 /// `Vec` will never automatically shrink itself, even if completely empty. This
245 /// ensures no unnecessary allocations or deallocations occur. Emptying a `Vec`
246 /// and then filling it back up to the same [`len()`] should incur no calls to
247 /// the allocator. If you wish to free up unused memory, use
248 /// [`shrink_to_fit`][`shrink_to_fit()`].
250 /// [`push`] and [`insert`] will never (re)allocate if the reported capacity is
251 /// sufficient. [`push`] and [`insert`] *will* (re)allocate if
252 /// [`len()`]` == `[`capacity()`]. That is, the reported capacity is completely
253 /// accurate, and can be relied on. It can even be used to manually free the memory
254 /// allocated by a `Vec` if desired. Bulk insertion methods *may* reallocate, even
255 /// when not necessary.
257 /// `Vec` does not guarantee any particular growth strategy when reallocating
258 /// when full, nor when [`reserve`] is called. The current strategy is basic
259 /// and it may prove desirable to use a non-constant growth factor. Whatever
260 /// strategy is used will of course guarantee `O(1)` amortized [`push`].
262 /// `vec![x; n]`, `vec![a, b, c, d]`, and
263 /// [`Vec::with_capacity(n)`][`Vec::with_capacity`], will all produce a `Vec`
264 /// with exactly the requested capacity. If [`len()`]` == `[`capacity()`],
265 /// (as is the case for the [`vec!`] macro), then a `Vec<T>` can be converted to
266 /// and from a [`Box<[T]>`][owned slice] without reallocating or moving the elements.
268 /// `Vec` will not specifically overwrite any data that is removed from it,
269 /// but also won't specifically preserve it. Its uninitialized memory is
270 /// scratch space that it may use however it wants. It will generally just do
271 /// whatever is most efficient or otherwise easy to implement. Do not rely on
272 /// removed data to be erased for security purposes. Even if you drop a `Vec`, its
273 /// buffer may simply be reused by another `Vec`. Even if you zero a `Vec`'s memory
274 /// first, that may not actually happen because the optimizer does not consider
275 /// this a side-effect that must be preserved.
277 /// `Vec` does not currently guarantee the order in which elements are dropped
278 /// (the order has changed in the past, and may change again).
280 /// [`vec!`]: ../../std/macro.vec.html
281 /// [`Index`]: ../../std/ops/trait.Index.html
282 /// [`String`]: ../../std/string/struct.String.html
283 /// [`&str`]: ../../std/primitive.str.html
284 /// [`Vec::with_capacity`]: ../../std/vec/struct.Vec.html#method.with_capacity
285 /// [`Vec::new()`]: ../../std/vec/struct.Vec.html#method.new
286 /// [`shrink_to_fit()`]: ../../std/vec/struct.Vec.html#method.shrink_to_fit
287 /// [`capacity()`]: ../../std/vec/struct.Vec.html#method.capacity
288 /// [`mem::size_of::<T>()`]: ../../std/mem/fn.size_of.html
289 /// [`len()`]: ../../std/vec/struct.Vec.html#method.len
290 /// [`push`]: ../../std/vec/struct.Vec.html#method.push
291 /// [`insert`]: ../../std/vec/struct.Vec.html#method.insert
292 /// [`reserve`]: ../../std/vec/struct.Vec.html#method.reserve
293 /// [owned slice]: ../../std/boxed/struct.Box.html
294 #[stable(feature = "rust1", since = "1.0.0")]
300 ////////////////////////////////////////////////////////////////////////////////
302 ////////////////////////////////////////////////////////////////////////////////
305 /// Constructs a new, empty `Vec<T>`.
307 /// The vector will not allocate until elements are pushed onto it.
312 /// # #![allow(unused_mut)]
313 /// let mut vec: Vec<i32> = Vec::new();
316 #[stable(feature = "rust1", since = "1.0.0")]
317 pub fn new() -> Vec
<T
> {
324 /// Constructs a new, empty `Vec<T>` with the specified capacity.
326 /// The vector will be able to hold exactly `capacity` elements without
327 /// reallocating. If `capacity` is 0, the vector will not allocate.
329 /// It is important to note that this function does not specify the *length*
330 /// of the returned vector, but only the *capacity*. For an explanation of
331 /// the difference between length and capacity, see *[Capacity and reallocation]*.
333 /// [Capacity and reallocation]: #capacity-and-reallocation
338 /// let mut vec = Vec::with_capacity(10);
340 /// // The vector contains no items, even though it has capacity for more
341 /// assert_eq!(vec.len(), 0);
343 /// // These are all done without reallocating...
348 /// // ...but this may make the vector reallocate
352 #[stable(feature = "rust1", since = "1.0.0")]
353 pub fn with_capacity(capacity
: usize) -> Vec
<T
> {
355 buf
: RawVec
::with_capacity(capacity
),
360 /// Creates a `Vec<T>` directly from the raw components of another vector.
364 /// This is highly unsafe, due to the number of invariants that aren't
367 /// * `ptr` needs to have been previously allocated via [`String`]/`Vec<T>`
368 /// (at least, it's highly likely to be incorrect if it wasn't).
369 /// * `length` needs to be less than or equal to `capacity`.
370 /// * `capacity` needs to be the capacity that the pointer was allocated with.
372 /// Violating these may cause problems like corrupting the allocator's
373 /// internal datastructures.
375 /// The ownership of `ptr` is effectively transferred to the
376 /// `Vec<T>` which may then deallocate, reallocate or change the
377 /// contents of memory pointed to by the pointer at will. Ensure
378 /// that nothing else uses the pointer after calling this
381 /// [`String`]: ../../std/string/struct.String.html
390 /// let mut v = vec![1, 2, 3];
392 /// // Pull out the various important pieces of information about `v`
393 /// let p = v.as_mut_ptr();
394 /// let len = v.len();
395 /// let cap = v.capacity();
398 /// // Cast `v` into the void: no destructor run, so we are in
399 /// // complete control of the allocation to which `p` points.
402 /// // Overwrite memory with 4, 5, 6
403 /// for i in 0..len as isize {
404 /// ptr::write(p.offset(i), 4 + i);
407 /// // Put everything back together into a Vec
408 /// let rebuilt = Vec::from_raw_parts(p, len, cap);
409 /// assert_eq!(rebuilt, [4, 5, 6]);
413 #[stable(feature = "rust1", since = "1.0.0")]
414 pub unsafe fn from_raw_parts(ptr
: *mut T
, length
: usize, capacity
: usize) -> Vec
<T
> {
416 buf
: RawVec
::from_raw_parts(ptr
, capacity
),
421 /// Returns the number of elements the vector can hold without
427 /// let vec: Vec<i32> = Vec::with_capacity(10);
428 /// assert_eq!(vec.capacity(), 10);
431 #[stable(feature = "rust1", since = "1.0.0")]
432 pub fn capacity(&self) -> usize {
436 /// Reserves capacity for at least `additional` more elements to be inserted
437 /// in the given `Vec<T>`. The collection may reserve more space to avoid
438 /// frequent reallocations.
442 /// Panics if the new capacity overflows `usize`.
447 /// let mut vec = vec![1];
449 /// assert!(vec.capacity() >= 11);
451 #[stable(feature = "rust1", since = "1.0.0")]
452 pub fn reserve(&mut self, additional
: usize) {
453 self.buf
.reserve(self.len
, additional
);
456 /// Reserves the minimum capacity for exactly `additional` more elements to
457 /// be inserted in the given `Vec<T>`. Does nothing if the capacity is already
460 /// Note that the allocator may give the collection more space than it
461 /// requests. Therefore capacity can not be relied upon to be precisely
462 /// minimal. Prefer `reserve` if future insertions are expected.
466 /// Panics if the new capacity overflows `usize`.
471 /// let mut vec = vec![1];
472 /// vec.reserve_exact(10);
473 /// assert!(vec.capacity() >= 11);
475 #[stable(feature = "rust1", since = "1.0.0")]
476 pub fn reserve_exact(&mut self, additional
: usize) {
477 self.buf
.reserve_exact(self.len
, additional
);
480 /// Shrinks the capacity of the vector as much as possible.
482 /// It will drop down as close as possible to the length but the allocator
483 /// may still inform the vector that there is space for a few more elements.
488 /// let mut vec = Vec::with_capacity(10);
489 /// vec.extend([1, 2, 3].iter().cloned());
490 /// assert_eq!(vec.capacity(), 10);
491 /// vec.shrink_to_fit();
492 /// assert!(vec.capacity() >= 3);
494 #[stable(feature = "rust1", since = "1.0.0")]
495 pub fn shrink_to_fit(&mut self) {
496 self.buf
.shrink_to_fit(self.len
);
499 /// Converts the vector into [`Box<[T]>`][owned slice].
501 /// Note that this will drop any excess capacity. Calling this and
502 /// converting back to a vector with [`into_vec()`] is equivalent to calling
503 /// [`shrink_to_fit()`].
505 /// [owned slice]: ../../std/boxed/struct.Box.html
506 /// [`into_vec()`]: ../../std/primitive.slice.html#method.into_vec
507 /// [`shrink_to_fit()`]: #method.shrink_to_fit
512 /// let v = vec![1, 2, 3];
514 /// let slice = v.into_boxed_slice();
517 /// Any excess capacity is removed:
520 /// let mut vec = Vec::with_capacity(10);
521 /// vec.extend([1, 2, 3].iter().cloned());
523 /// assert_eq!(vec.capacity(), 10);
524 /// let slice = vec.into_boxed_slice();
525 /// assert_eq!(slice.into_vec().capacity(), 3);
527 #[stable(feature = "rust1", since = "1.0.0")]
528 pub fn into_boxed_slice(mut self) -> Box
<[T
]> {
530 self.shrink_to_fit();
531 let buf
= ptr
::read(&self.buf
);
537 /// Shortens the vector, keeping the first `len` elements and dropping
540 /// If `len` is greater than the vector's current length, this has no
543 /// The [`drain`] method can emulate `truncate`, but causes the excess
544 /// elements to be returned instead of dropped.
548 /// Truncating a five element vector to two elements:
551 /// let mut vec = vec![1, 2, 3, 4, 5];
553 /// assert_eq!(vec, [1, 2]);
556 /// No truncation occurs when `len` is greater than the vector's current
560 /// let mut vec = vec![1, 2, 3];
562 /// assert_eq!(vec, [1, 2, 3]);
565 /// Truncating when `len == 0` is equivalent to calling the [`clear`]
569 /// let mut vec = vec![1, 2, 3];
571 /// assert_eq!(vec, []);
574 /// [`clear`]: #method.clear
575 /// [`drain`]: #method.drain
576 #[stable(feature = "rust1", since = "1.0.0")]
577 pub fn truncate(&mut self, len
: usize) {
579 // drop any extra elements
580 while len
< self.len
{
581 // decrement len before the drop_in_place(), so a panic on Drop
582 // doesn't re-drop the just-failed value.
585 ptr
::drop_in_place(self.get_unchecked_mut(len
));
590 /// Extracts a slice containing the entire vector.
592 /// Equivalent to `&s[..]`.
597 /// use std::io::{self, Write};
598 /// let buffer = vec![1, 2, 3, 5, 8];
599 /// io::sink().write(buffer.as_slice()).unwrap();
602 #[stable(feature = "vec_as_slice", since = "1.7.0")]
603 pub fn as_slice(&self) -> &[T
] {
607 /// Extracts a mutable slice of the entire vector.
609 /// Equivalent to `&mut s[..]`.
614 /// use std::io::{self, Read};
615 /// let mut buffer = vec![0; 3];
616 /// io::repeat(0b101).read_exact(buffer.as_mut_slice()).unwrap();
619 #[stable(feature = "vec_as_slice", since = "1.7.0")]
620 pub fn as_mut_slice(&mut self) -> &mut [T
] {
624 /// Sets the length of a vector.
626 /// This will explicitly set the size of the vector, without actually
627 /// modifying its buffers, so it is up to the caller to ensure that the
628 /// vector is actually the specified size.
635 /// let mut vec = vec!['r', 'u', 's', 't'];
638 /// ptr::drop_in_place(&mut vec[3]);
641 /// assert_eq!(vec, ['r', 'u', 's']);
644 /// In this example, there is a memory leak since the memory locations
645 /// owned by the inner vectors were not freed prior to the `set_len` call:
648 /// let mut vec = vec![vec![1, 0, 0],
656 /// In this example, the vector gets expanded from zero to four items
657 /// without any memory allocations occurring, resulting in vector
658 /// values of unallocated memory:
661 /// let mut vec: Vec<char> = Vec::new();
668 #[stable(feature = "rust1", since = "1.0.0")]
669 pub unsafe fn set_len(&mut self, len
: usize) {
673 /// Removes an element from anywhere in the vector and return it, replacing
674 /// it with the last element.
676 /// This does not preserve ordering, but is O(1).
680 /// Panics if `index` is out of bounds.
685 /// let mut v = vec!["foo", "bar", "baz", "qux"];
687 /// assert_eq!(v.swap_remove(1), "bar");
688 /// assert_eq!(v, ["foo", "qux", "baz"]);
690 /// assert_eq!(v.swap_remove(0), "foo");
691 /// assert_eq!(v, ["baz", "qux"]);
694 #[stable(feature = "rust1", since = "1.0.0")]
695 pub fn swap_remove(&mut self, index
: usize) -> T
{
696 let length
= self.len();
697 self.swap(index
, length
- 1);
701 /// Inserts an element at position `index` within the vector, shifting all
702 /// elements after it to the right.
706 /// Panics if `index` is out of bounds.
711 /// let mut vec = vec![1, 2, 3];
712 /// vec.insert(1, 4);
713 /// assert_eq!(vec, [1, 4, 2, 3]);
714 /// vec.insert(4, 5);
715 /// assert_eq!(vec, [1, 4, 2, 3, 5]);
717 #[stable(feature = "rust1", since = "1.0.0")]
718 pub fn insert(&mut self, index
: usize, element
: T
) {
719 let len
= self.len();
720 assert
!(index
<= len
);
722 // space for the new element
723 if len
== self.buf
.cap() {
729 // The spot to put the new value
731 let p
= self.as_mut_ptr().offset(index
as isize);
732 // Shift everything over to make space. (Duplicating the
733 // `index`th element into two consecutive places.)
734 ptr
::copy(p
, p
.offset(1), len
- index
);
735 // Write it in, overwriting the first copy of the `index`th
737 ptr
::write(p
, element
);
739 self.set_len(len
+ 1);
743 /// Removes and returns the element at position `index` within the vector,
744 /// shifting all elements after it to the left.
748 /// Panics if `index` is out of bounds.
753 /// let mut v = vec![1, 2, 3];
754 /// assert_eq!(v.remove(1), 2);
755 /// assert_eq!(v, [1, 3]);
757 #[stable(feature = "rust1", since = "1.0.0")]
758 pub fn remove(&mut self, index
: usize) -> T
{
759 let len
= self.len();
760 assert
!(index
< len
);
765 // the place we are taking from.
766 let ptr
= self.as_mut_ptr().offset(index
as isize);
767 // copy it out, unsafely having a copy of the value on
768 // the stack and in the vector at the same time.
769 ret
= ptr
::read(ptr
);
771 // Shift everything down to fill in that spot.
772 ptr
::copy(ptr
.offset(1), ptr
, len
- index
- 1);
774 self.set_len(len
- 1);
779 /// Retains only the elements specified by the predicate.
781 /// In other words, remove all elements `e` such that `f(&e)` returns `false`.
782 /// This method operates in place and preserves the order of the retained
788 /// let mut vec = vec![1, 2, 3, 4];
789 /// vec.retain(|&x| x%2 == 0);
790 /// assert_eq!(vec, [2, 4]);
792 #[stable(feature = "rust1", since = "1.0.0")]
793 pub fn retain
<F
>(&mut self, mut f
: F
)
794 where F
: FnMut(&T
) -> bool
796 let len
= self.len();
810 self.truncate(len
- del
);
814 /// Removes consecutive elements in the vector that resolve to the same key.
816 /// If the vector is sorted, this removes all duplicates.
821 /// #![feature(dedup_by)]
823 /// let mut vec = vec![10, 20, 21, 30, 20];
825 /// vec.dedup_by_key(|i| *i / 10);
827 /// assert_eq!(vec, [10, 20, 30, 20]);
829 #[unstable(feature = "dedup_by", reason = "recently added", issue = "37087")]
831 pub fn dedup_by_key
<F
, K
>(&mut self, mut key
: F
) where F
: FnMut(&mut T
) -> K
, K
: PartialEq
{
832 self.dedup_by(|a
, b
| key(a
) == key(b
))
835 /// Removes consecutive elements in the vector that resolve to the same key.
837 /// If the vector is sorted, this removes all duplicates.
842 /// #![feature(dedup_by)]
843 /// use std::ascii::AsciiExt;
845 /// let mut vec = vec!["foo", "bar", "Bar", "baz", "bar"];
847 /// vec.dedup_by(|a, b| a.eq_ignore_ascii_case(b));
849 /// assert_eq!(vec, ["foo", "bar", "baz", "bar"]);
851 #[unstable(feature = "dedup_by", reason = "recently added", issue = "37087")]
852 pub fn dedup_by
<F
>(&mut self, mut same_bucket
: F
) where F
: FnMut(&mut T
, &mut T
) -> bool
{
854 // Although we have a mutable reference to `self`, we cannot make
855 // *arbitrary* changes. The `same_bucket` calls could panic, so we
856 // must ensure that the vector is in a valid state at all time.
858 // The way that we handle this is by using swaps; we iterate
859 // over all the elements, swapping as we go so that at the end
860 // the elements we wish to keep are in the front, and those we
861 // wish to reject are at the back. We can then truncate the
862 // vector. This operation is still O(n).
864 // Example: We start in this state, where `r` represents "next
865 // read" and `w` represents "next_write`.
868 // +---+---+---+---+---+---+
869 // | 0 | 1 | 1 | 2 | 3 | 3 |
870 // +---+---+---+---+---+---+
873 // Comparing self[r] against self[w-1], this is not a duplicate, so
874 // we swap self[r] and self[w] (no effect as r==w) and then increment both
875 // r and w, leaving us with:
878 // +---+---+---+---+---+---+
879 // | 0 | 1 | 1 | 2 | 3 | 3 |
880 // +---+---+---+---+---+---+
883 // Comparing self[r] against self[w-1], this value is a duplicate,
884 // so we increment `r` but leave everything else unchanged:
887 // +---+---+---+---+---+---+
888 // | 0 | 1 | 1 | 2 | 3 | 3 |
889 // +---+---+---+---+---+---+
892 // Comparing self[r] against self[w-1], this is not a duplicate,
893 // so swap self[r] and self[w] and advance r and w:
896 // +---+---+---+---+---+---+
897 // | 0 | 1 | 2 | 1 | 3 | 3 |
898 // +---+---+---+---+---+---+
901 // Not a duplicate, repeat:
904 // +---+---+---+---+---+---+
905 // | 0 | 1 | 2 | 3 | 1 | 3 |
906 // +---+---+---+---+---+---+
909 // Duplicate, advance r. End of vec. Truncate to w.
916 // Avoid bounds checks by using raw pointers.
917 let p
= self.as_mut_ptr();
918 let mut r
: usize = 1;
919 let mut w
: usize = 1;
922 let p_r
= p
.offset(r
as isize);
923 let p_wm1
= p
.offset((w
- 1) as isize);
924 if !same_bucket(&mut *p_r
, &mut *p_wm1
) {
926 let p_w
= p_wm1
.offset(1);
927 mem
::swap(&mut *p_r
, &mut *p_w
);
938 /// Appends an element to the back of a collection.
942 /// Panics if the number of elements in the vector overflows a `usize`.
947 /// let mut vec = vec![1, 2];
949 /// assert_eq!(vec, [1, 2, 3]);
952 #[stable(feature = "rust1", since = "1.0.0")]
953 pub fn push(&mut self, value
: T
) {
954 // This will panic or abort if we would allocate > isize::MAX bytes
955 // or if the length increment would overflow for zero-sized types.
956 if self.len
== self.buf
.cap() {
960 let end
= self.as_mut_ptr().offset(self.len
as isize);
961 ptr
::write(end
, value
);
966 /// Removes the last element from a vector and returns it, or [`None`] if it
969 /// [`None`]: ../../std/option/enum.Option.html#variant.None
974 /// let mut vec = vec![1, 2, 3];
975 /// assert_eq!(vec.pop(), Some(3));
976 /// assert_eq!(vec, [1, 2]);
979 #[stable(feature = "rust1", since = "1.0.0")]
980 pub fn pop(&mut self) -> Option
<T
> {
986 Some(ptr
::read(self.get_unchecked(self.len())))
991 /// Moves all the elements of `other` into `Self`, leaving `other` empty.
995 /// Panics if the number of elements in the vector overflows a `usize`.
1000 /// let mut vec = vec![1, 2, 3];
1001 /// let mut vec2 = vec![4, 5, 6];
1002 /// vec.append(&mut vec2);
1003 /// assert_eq!(vec, [1, 2, 3, 4, 5, 6]);
1004 /// assert_eq!(vec2, []);
1007 #[stable(feature = "append", since = "1.4.0")]
1008 pub fn append(&mut self, other
: &mut Self) {
1009 self.reserve(other
.len());
1010 let len
= self.len();
1012 ptr
::copy_nonoverlapping(other
.as_ptr(), self.get_unchecked_mut(len
), other
.len());
1015 self.len
+= other
.len();
1021 /// Create a draining iterator that removes the specified range in the vector
1022 /// and yields the removed items.
1024 /// Note 1: The element range is removed even if the iterator is not
1025 /// consumed until the end.
1027 /// Note 2: It is unspecified how many elements are removed from the vector,
1028 /// if the `Drain` value is leaked.
1032 /// Panics if the starting point is greater than the end point or if
1033 /// the end point is greater than the length of the vector.
1038 /// let mut v = vec![1, 2, 3];
1039 /// let u: Vec<_> = v.drain(1..).collect();
1040 /// assert_eq!(v, &[1]);
1041 /// assert_eq!(u, &[2, 3]);
1043 /// // A full range clears the vector
1045 /// assert_eq!(v, &[]);
1047 #[stable(feature = "drain", since = "1.6.0")]
1048 pub fn drain
<R
>(&mut self, range
: R
) -> Drain
<T
>
1049 where R
: RangeArgument
<usize>
1053 // When the Drain is first created, it shortens the length of
1054 // the source vector to make sure no uninitalized or moved-from elements
1055 // are accessible at all if the Drain's destructor never gets to run.
1057 // Drain will ptr::read out the values to remove.
1058 // When finished, remaining tail of the vec is copied back to cover
1059 // the hole, and the vector length is restored to the new length.
1061 let len
= self.len();
1062 let start
= *range
.start().unwrap_or(&0);
1063 let end
= *range
.end().unwrap_or(&len
);
1064 assert
!(start
<= end
);
1065 assert
!(end
<= len
);
1068 // set self.vec length's to start, to be safe in case Drain is leaked
1069 self.set_len(start
);
1070 // Use the borrow in the IterMut to indicate borrowing behavior of the
1071 // whole Drain iterator (like &mut T).
1072 let range_slice
= slice
::from_raw_parts_mut(self.as_mut_ptr().offset(start
as isize),
1076 tail_len
: len
- end
,
1077 iter
: range_slice
.iter(),
1078 vec
: Shared
::new(self as *mut _
),
1083 /// Clears the vector, removing all values.
1088 /// let mut v = vec![1, 2, 3];
1092 /// assert!(v.is_empty());
1095 #[stable(feature = "rust1", since = "1.0.0")]
1096 pub fn clear(&mut self) {
1100 /// Returns the number of elements in the vector.
1105 /// let a = vec![1, 2, 3];
1106 /// assert_eq!(a.len(), 3);
1109 #[stable(feature = "rust1", since = "1.0.0")]
1110 pub fn len(&self) -> usize {
1114 /// Returns `true` if the vector contains no elements.
1119 /// let mut v = Vec::new();
1120 /// assert!(v.is_empty());
1123 /// assert!(!v.is_empty());
1125 #[stable(feature = "rust1", since = "1.0.0")]
1126 pub fn is_empty(&self) -> bool
{
1130 /// Splits the collection into two at the given index.
1132 /// Returns a newly allocated `Self`. `self` contains elements `[0, at)`,
1133 /// and the returned `Self` contains elements `[at, len)`.
1135 /// Note that the capacity of `self` does not change.
1139 /// Panics if `at > len`.
1144 /// let mut vec = vec![1,2,3];
1145 /// let vec2 = vec.split_off(1);
1146 /// assert_eq!(vec, [1]);
1147 /// assert_eq!(vec2, [2, 3]);
1150 #[stable(feature = "split_off", since = "1.4.0")]
1151 pub fn split_off(&mut self, at
: usize) -> Self {
1152 assert
!(at
<= self.len(), "`at` out of bounds");
1154 let other_len
= self.len
- at
;
1155 let mut other
= Vec
::with_capacity(other_len
);
1157 // Unsafely `set_len` and copy items to `other`.
1160 other
.set_len(other_len
);
1162 ptr
::copy_nonoverlapping(self.as_ptr().offset(at
as isize),
1170 impl<T
: Clone
> Vec
<T
> {
1171 /// Resizes the `Vec` in-place so that `len()` is equal to `new_len`.
1173 /// If `new_len` is greater than `len()`, the `Vec` is extended by the
1174 /// difference, with each additional slot filled with `value`.
1175 /// If `new_len` is less than `len()`, the `Vec` is simply truncated.
1180 /// let mut vec = vec!["hello"];
1181 /// vec.resize(3, "world");
1182 /// assert_eq!(vec, ["hello", "world", "world"]);
1184 /// let mut vec = vec![1, 2, 3, 4];
1185 /// vec.resize(2, 0);
1186 /// assert_eq!(vec, [1, 2]);
1188 #[stable(feature = "vec_resize", since = "1.5.0")]
1189 pub fn resize(&mut self, new_len
: usize, value
: T
) {
1190 let len
= self.len();
1193 self.extend_with_element(new_len
- len
, value
);
1195 self.truncate(new_len
);
1199 /// Extend the vector by `n` additional clones of `value`.
1200 fn extend_with_element(&mut self, n
: usize, value
: T
) {
1204 let mut ptr
= self.as_mut_ptr().offset(self.len() as isize);
1205 // Use SetLenOnDrop to work around bug where compiler
1206 // may not realize the store through `ptr` trough self.set_len()
1208 let mut local_len
= SetLenOnDrop
::new(&mut self.len
);
1210 // Write all elements except the last one
1212 ptr
::write(ptr
, value
.clone());
1213 ptr
= ptr
.offset(1);
1214 // Increment the length in every step in case clone() panics
1215 local_len
.increment_len(1);
1219 // We can write the last element directly without cloning needlessly
1220 ptr
::write(ptr
, value
);
1221 local_len
.increment_len(1);
1224 // len set by scope guard
1228 /// Clones and appends all elements in a slice to the `Vec`.
1230 /// Iterates over the slice `other`, clones each element, and then appends
1231 /// it to this `Vec`. The `other` vector is traversed in-order.
1233 /// Note that this function is same as `extend` except that it is
1234 /// specialized to work with slices instead. If and when Rust gets
1235 /// specialization this function will likely be deprecated (but still
1241 /// let mut vec = vec![1];
1242 /// vec.extend_from_slice(&[2, 3, 4]);
1243 /// assert_eq!(vec, [1, 2, 3, 4]);
1245 #[stable(feature = "vec_extend_from_slice", since = "1.6.0")]
1246 pub fn extend_from_slice(&mut self, other
: &[T
]) {
1247 self.spec_extend(other
.iter())
1251 // Set the length of the vec when the `SetLenOnDrop` value goes out of scope.
1253 // The idea is: The length field in SetLenOnDrop is a local variable
1254 // that the optimizer will see does not alias with any stores through the Vec's data
1255 // pointer. This is a workaround for alias analysis issue #32155
1256 struct SetLenOnDrop
<'a
> {
1261 impl<'a
> SetLenOnDrop
<'a
> {
1263 fn new(len
: &'a
mut usize) -> Self {
1264 SetLenOnDrop { local_len: *len, len: len }
1268 fn increment_len(&mut self, increment
: usize) {
1269 self.local_len
+= increment
;
1273 impl<'a
> Drop
for SetLenOnDrop
<'a
> {
1275 fn drop(&mut self) {
1276 *self.len
= self.local_len
;
1280 impl<T
: PartialEq
> Vec
<T
> {
1281 /// Removes consecutive repeated elements in the vector.
1283 /// If the vector is sorted, this removes all duplicates.
1288 /// let mut vec = vec![1, 2, 2, 3, 2];
1292 /// assert_eq!(vec, [1, 2, 3, 2]);
1294 #[stable(feature = "rust1", since = "1.0.0")]
1296 pub fn dedup(&mut self) {
1297 self.dedup_by(|a
, b
| a
== b
)
1301 ////////////////////////////////////////////////////////////////////////////////
1302 // Internal methods and functions
1303 ////////////////////////////////////////////////////////////////////////////////
1306 #[stable(feature = "rust1", since = "1.0.0")]
1307 pub fn from_elem
<T
: Clone
>(elem
: T
, n
: usize) -> Vec
<T
> {
1308 let mut v
= Vec
::with_capacity(n
);
1309 v
.extend_with_element(n
, elem
);
1313 ////////////////////////////////////////////////////////////////////////////////
1314 // Common trait implementations for Vec
1315 ////////////////////////////////////////////////////////////////////////////////
1317 #[stable(feature = "rust1", since = "1.0.0")]
1318 impl<T
: Clone
> Clone
for Vec
<T
> {
1320 fn clone(&self) -> Vec
<T
> {
1321 <[T
]>::to_vec(&**self)
1324 // HACK(japaric): with cfg(test) the inherent `[T]::to_vec` method, which is
1325 // required for this method definition, is not available. Instead use the
1326 // `slice::to_vec` function which is only available with cfg(test)
1327 // NB see the slice::hack module in slice.rs for more information
1329 fn clone(&self) -> Vec
<T
> {
1330 ::slice
::to_vec(&**self)
1333 fn clone_from(&mut self, other
: &Vec
<T
>) {
1334 // drop anything in self that will not be overwritten
1335 self.truncate(other
.len());
1336 let len
= self.len();
1338 // reuse the contained values' allocations/resources.
1339 self.clone_from_slice(&other
[..len
]);
1341 // self.len <= other.len due to the truncate above, so the
1342 // slice here is always in-bounds.
1343 self.extend_from_slice(&other
[len
..]);
1347 #[stable(feature = "rust1", since = "1.0.0")]
1348 impl<T
: Hash
> Hash
for Vec
<T
> {
1350 fn hash
<H
: hash
::Hasher
>(&self, state
: &mut H
) {
1351 Hash
::hash(&**self, state
)
1355 #[stable(feature = "rust1", since = "1.0.0")]
1356 impl<T
> Index
<usize> for Vec
<T
> {
1360 fn index(&self, index
: usize) -> &T
{
1361 // NB built-in indexing via `&[T]`
1366 #[stable(feature = "rust1", since = "1.0.0")]
1367 impl<T
> IndexMut
<usize> for Vec
<T
> {
1369 fn index_mut(&mut self, index
: usize) -> &mut T
{
1370 // NB built-in indexing via `&mut [T]`
1371 &mut (**self)[index
]
1376 #[stable(feature = "rust1", since = "1.0.0")]
1377 impl<T
> ops
::Index
<ops
::Range
<usize>> for Vec
<T
> {
1381 fn index(&self, index
: ops
::Range
<usize>) -> &[T
] {
1382 Index
::index(&**self, index
)
1385 #[stable(feature = "rust1", since = "1.0.0")]
1386 impl<T
> ops
::Index
<ops
::RangeTo
<usize>> for Vec
<T
> {
1390 fn index(&self, index
: ops
::RangeTo
<usize>) -> &[T
] {
1391 Index
::index(&**self, index
)
1394 #[stable(feature = "rust1", since = "1.0.0")]
1395 impl<T
> ops
::Index
<ops
::RangeFrom
<usize>> for Vec
<T
> {
1399 fn index(&self, index
: ops
::RangeFrom
<usize>) -> &[T
] {
1400 Index
::index(&**self, index
)
1403 #[stable(feature = "rust1", since = "1.0.0")]
1404 impl<T
> ops
::Index
<ops
::RangeFull
> for Vec
<T
> {
1408 fn index(&self, _index
: ops
::RangeFull
) -> &[T
] {
1412 #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
1413 impl<T
> ops
::Index
<ops
::RangeInclusive
<usize>> for Vec
<T
> {
1417 fn index(&self, index
: ops
::RangeInclusive
<usize>) -> &[T
] {
1418 Index
::index(&**self, index
)
1421 #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
1422 impl<T
> ops
::Index
<ops
::RangeToInclusive
<usize>> for Vec
<T
> {
1426 fn index(&self, index
: ops
::RangeToInclusive
<usize>) -> &[T
] {
1427 Index
::index(&**self, index
)
1431 #[stable(feature = "rust1", since = "1.0.0")]
1432 impl<T
> ops
::IndexMut
<ops
::Range
<usize>> for Vec
<T
> {
1434 fn index_mut(&mut self, index
: ops
::Range
<usize>) -> &mut [T
] {
1435 IndexMut
::index_mut(&mut **self, index
)
1438 #[stable(feature = "rust1", since = "1.0.0")]
1439 impl<T
> ops
::IndexMut
<ops
::RangeTo
<usize>> for Vec
<T
> {
1441 fn index_mut(&mut self, index
: ops
::RangeTo
<usize>) -> &mut [T
] {
1442 IndexMut
::index_mut(&mut **self, index
)
1445 #[stable(feature = "rust1", since = "1.0.0")]
1446 impl<T
> ops
::IndexMut
<ops
::RangeFrom
<usize>> for Vec
<T
> {
1448 fn index_mut(&mut self, index
: ops
::RangeFrom
<usize>) -> &mut [T
] {
1449 IndexMut
::index_mut(&mut **self, index
)
1452 #[stable(feature = "rust1", since = "1.0.0")]
1453 impl<T
> ops
::IndexMut
<ops
::RangeFull
> for Vec
<T
> {
1455 fn index_mut(&mut self, _index
: ops
::RangeFull
) -> &mut [T
] {
1459 #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
1460 impl<T
> ops
::IndexMut
<ops
::RangeInclusive
<usize>> for Vec
<T
> {
1462 fn index_mut(&mut self, index
: ops
::RangeInclusive
<usize>) -> &mut [T
] {
1463 IndexMut
::index_mut(&mut **self, index
)
1466 #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
1467 impl<T
> ops
::IndexMut
<ops
::RangeToInclusive
<usize>> for Vec
<T
> {
1469 fn index_mut(&mut self, index
: ops
::RangeToInclusive
<usize>) -> &mut [T
] {
1470 IndexMut
::index_mut(&mut **self, index
)
1474 #[stable(feature = "rust1", since = "1.0.0")]
1475 impl<T
> ops
::Deref
for Vec
<T
> {
1478 fn deref(&self) -> &[T
] {
1480 let p
= self.buf
.ptr();
1481 assume(!p
.is_null());
1482 slice
::from_raw_parts(p
, self.len
)
1487 #[stable(feature = "rust1", since = "1.0.0")]
1488 impl<T
> ops
::DerefMut
for Vec
<T
> {
1489 fn deref_mut(&mut self) -> &mut [T
] {
1491 let ptr
= self.buf
.ptr();
1492 assume(!ptr
.is_null());
1493 slice
::from_raw_parts_mut(ptr
, self.len
)
1498 #[stable(feature = "rust1", since = "1.0.0")]
1499 impl<T
> FromIterator
<T
> for Vec
<T
> {
1501 fn from_iter
<I
: IntoIterator
<Item
= T
>>(iter
: I
) -> Vec
<T
> {
1502 <Self as SpecExtend
<_
, _
>>::from_iter(iter
.into_iter())
1506 #[stable(feature = "rust1", since = "1.0.0")]
1507 impl<T
> IntoIterator
for Vec
<T
> {
1509 type IntoIter
= IntoIter
<T
>;
1511 /// Creates a consuming iterator, that is, one that moves each value out of
1512 /// the vector (from start to end). The vector cannot be used after calling
1518 /// let v = vec!["a".to_string(), "b".to_string()];
1519 /// for s in v.into_iter() {
1520 /// // s has type String, not &String
1521 /// println!("{}", s);
1525 fn into_iter(mut self) -> IntoIter
<T
> {
1527 let begin
= self.as_mut_ptr();
1528 assume(!begin
.is_null());
1529 let end
= if mem
::size_of
::<T
>() == 0 {
1530 arith_offset(begin
as *const i8, self.len() as isize) as *const T
1532 begin
.offset(self.len() as isize) as *const T
1534 let cap
= self.buf
.cap();
1537 buf
: Shared
::new(begin
),
1546 #[stable(feature = "rust1", since = "1.0.0")]
1547 impl<'a
, T
> IntoIterator
for &'a Vec
<T
> {
1549 type IntoIter
= slice
::Iter
<'a
, T
>;
1551 fn into_iter(self) -> slice
::Iter
<'a
, T
> {
1556 #[stable(feature = "rust1", since = "1.0.0")]
1557 impl<'a
, T
> IntoIterator
for &'a
mut Vec
<T
> {
1558 type Item
= &'a
mut T
;
1559 type IntoIter
= slice
::IterMut
<'a
, T
>;
1561 fn into_iter(mut self) -> slice
::IterMut
<'a
, T
> {
1566 #[stable(feature = "rust1", since = "1.0.0")]
1567 impl<T
> Extend
<T
> for Vec
<T
> {
1569 fn extend
<I
: IntoIterator
<Item
= T
>>(&mut self, iter
: I
) {
1570 self.spec_extend(iter
.into_iter())
1574 // Specialization trait used for Vec::from_iter and Vec::extend
1575 trait SpecExtend
<T
, I
> {
1576 fn from_iter(iter
: I
) -> Self;
1577 fn spec_extend(&mut self, iter
: I
);
1580 impl<T
, I
> SpecExtend
<T
, I
> for Vec
<T
>
1581 where I
: Iterator
<Item
=T
>,
1583 default fn from_iter(mut iterator
: I
) -> Self {
1584 // Unroll the first iteration, as the vector is going to be
1585 // expanded on this iteration in every case when the iterable is not
1586 // empty, but the loop in extend_desugared() is not going to see the
1587 // vector being full in the few subsequent loop iterations.
1588 // So we get better branch prediction.
1589 let mut vector
= match iterator
.next() {
1590 None
=> return Vec
::new(),
1592 let (lower
, _
) = iterator
.size_hint();
1593 let mut vector
= Vec
::with_capacity(lower
.saturating_add(1));
1595 ptr
::write(vector
.get_unchecked_mut(0), element
);
1601 vector
.spec_extend(iterator
);
1605 default fn spec_extend(&mut self, iter
: I
) {
1606 self.extend_desugared(iter
)
1610 impl<T
, I
> SpecExtend
<T
, I
> for Vec
<T
>
1611 where I
: TrustedLen
<Item
=T
>,
1613 fn from_iter(iterator
: I
) -> Self {
1614 let mut vector
= Vec
::new();
1615 vector
.spec_extend(iterator
);
1619 fn spec_extend(&mut self, iterator
: I
) {
1620 // This is the case for a TrustedLen iterator.
1621 let (low
, high
) = iterator
.size_hint();
1622 if let Some(high_value
) = high
{
1623 debug_assert_eq
!(low
, high_value
,
1624 "TrustedLen iterator's size hint is not exact: {:?}",
1627 if let Some(additional
) = high
{
1628 self.reserve(additional
);
1630 let mut ptr
= self.as_mut_ptr().offset(self.len() as isize);
1631 let mut local_len
= SetLenOnDrop
::new(&mut self.len
);
1632 for element
in iterator
{
1633 ptr
::write(ptr
, element
);
1634 ptr
= ptr
.offset(1);
1635 // NB can't overflow since we would have had to alloc the address space
1636 local_len
.increment_len(1);
1640 self.extend_desugared(iterator
)
1645 impl<'a
, T
: 'a
, I
> SpecExtend
<&'a T
, I
> for Vec
<T
>
1646 where I
: Iterator
<Item
=&'a T
>,
1649 default fn from_iter(iterator
: I
) -> Self {
1650 SpecExtend
::from_iter(iterator
.cloned())
1653 default fn spec_extend(&mut self, iterator
: I
) {
1654 self.spec_extend(iterator
.cloned())
1658 impl<'a
, T
: 'a
> SpecExtend
<&'a T
, slice
::Iter
<'a
, T
>> for Vec
<T
>
1661 fn spec_extend(&mut self, iterator
: slice
::Iter
<'a
, T
>) {
1662 let slice
= iterator
.as_slice();
1663 self.reserve(slice
.len());
1665 let len
= self.len();
1666 self.set_len(len
+ slice
.len());
1667 self.get_unchecked_mut(len
..).copy_from_slice(slice
);
1673 fn extend_desugared
<I
: Iterator
<Item
= T
>>(&mut self, mut iterator
: I
) {
1674 // This is the case for a general iterator.
1676 // This function should be the moral equivalent of:
1678 // for item in iterator {
1681 while let Some(element
) = iterator
.next() {
1682 let len
= self.len();
1683 if len
== self.capacity() {
1684 let (lower
, _
) = iterator
.size_hint();
1685 self.reserve(lower
.saturating_add(1));
1688 ptr
::write(self.get_unchecked_mut(len
), element
);
1689 // NB can't overflow since we would have had to alloc the address space
1690 self.set_len(len
+ 1);
1696 #[stable(feature = "extend_ref", since = "1.2.0")]
1697 impl<'a
, T
: 'a
+ Copy
> Extend
<&'a T
> for Vec
<T
> {
1698 fn extend
<I
: IntoIterator
<Item
= &'a T
>>(&mut self, iter
: I
) {
1699 self.spec_extend(iter
.into_iter())
1703 macro_rules
! __impl_slice_eq1
{
1704 ($Lhs
: ty
, $Rhs
: ty
) => {
1705 __impl_slice_eq1
! { $Lhs, $Rhs, Sized }
1707 ($Lhs
: ty
, $Rhs
: ty
, $Bound
: ident
) => {
1708 #[stable(feature = "rust1", since = "1.0.0")]
1709 impl<'a
, 'b
, A
: $Bound
, B
> PartialEq
<$Rhs
> for $Lhs
where A
: PartialEq
<B
> {
1711 fn eq(&self, other
: &$Rhs
) -> bool { self[..] == other[..] }
1713 fn ne(&self, other
: &$Rhs
) -> bool { self[..] != other[..] }
1718 __impl_slice_eq1
! { Vec<A>, Vec<B> }
1719 __impl_slice_eq1
! { Vec<A>, &'b [B] }
1720 __impl_slice_eq1
! { Vec<A>, &'b mut [B] }
1721 __impl_slice_eq1
! { Cow<'a, [A]>, &'b [B], Clone }
1722 __impl_slice_eq1
! { Cow<'a, [A]>, &'b mut [B], Clone }
1723 __impl_slice_eq1
! { Cow<'a, [A]>, Vec<B>, Clone }
1725 macro_rules
! array_impls
{
1728 // NOTE: some less important impls are omitted to reduce code bloat
1729 __impl_slice_eq1
! { Vec<A>, [B; $N] }
1730 __impl_slice_eq1
! { Vec<A>, &'b [B; $N] }
1731 // __impl_slice_eq1! { Vec<A>, &'b mut [B; $N] }
1732 // __impl_slice_eq1! { Cow<'a, [A]>, [B; $N], Clone }
1733 // __impl_slice_eq1! { Cow<'a, [A]>, &'b [B; $N], Clone }
1734 // __impl_slice_eq1! { Cow<'a, [A]>, &'b mut [B; $N], Clone }
1741 10 11 12 13 14 15 16 17 18 19
1742 20 21 22 23 24 25 26 27 28 29
1746 #[stable(feature = "rust1", since = "1.0.0")]
1747 impl<T
: PartialOrd
> PartialOrd
for Vec
<T
> {
1749 fn partial_cmp(&self, other
: &Vec
<T
>) -> Option
<Ordering
> {
1750 PartialOrd
::partial_cmp(&**self, &**other
)
1754 #[stable(feature = "rust1", since = "1.0.0")]
1755 impl<T
: Eq
> Eq
for Vec
<T
> {}
1757 #[stable(feature = "rust1", since = "1.0.0")]
1758 impl<T
: Ord
> Ord
for Vec
<T
> {
1760 fn cmp(&self, other
: &Vec
<T
>) -> Ordering
{
1761 Ord
::cmp(&**self, &**other
)
1765 #[stable(feature = "rust1", since = "1.0.0")]
1766 impl<T
> Drop
for Vec
<T
> {
1767 #[unsafe_destructor_blind_to_params]
1768 fn drop(&mut self) {
1771 ptr
::drop_in_place(&mut self[..]);
1773 // RawVec handles deallocation
1777 #[stable(feature = "rust1", since = "1.0.0")]
1778 impl<T
> Default
for Vec
<T
> {
1779 /// Creates an empty `Vec<T>`.
1780 fn default() -> Vec
<T
> {
1785 #[stable(feature = "rust1", since = "1.0.0")]
1786 impl<T
: fmt
::Debug
> fmt
::Debug
for Vec
<T
> {
1787 fn fmt(&self, f
: &mut fmt
::Formatter
) -> fmt
::Result
{
1788 fmt
::Debug
::fmt(&**self, f
)
1792 #[stable(feature = "rust1", since = "1.0.0")]
1793 impl<T
> AsRef
<Vec
<T
>> for Vec
<T
> {
1794 fn as_ref(&self) -> &Vec
<T
> {
1799 #[stable(feature = "vec_as_mut", since = "1.5.0")]
1800 impl<T
> AsMut
<Vec
<T
>> for Vec
<T
> {
1801 fn as_mut(&mut self) -> &mut Vec
<T
> {
1806 #[stable(feature = "rust1", since = "1.0.0")]
1807 impl<T
> AsRef
<[T
]> for Vec
<T
> {
1808 fn as_ref(&self) -> &[T
] {
1813 #[stable(feature = "vec_as_mut", since = "1.5.0")]
1814 impl<T
> AsMut
<[T
]> for Vec
<T
> {
1815 fn as_mut(&mut self) -> &mut [T
] {
1820 #[stable(feature = "rust1", since = "1.0.0")]
1821 impl<'a
, T
: Clone
> From
<&'a
[T
]> for Vec
<T
> {
1823 fn from(s
: &'a
[T
]) -> Vec
<T
> {
1827 fn from(s
: &'a
[T
]) -> Vec
<T
> {
1832 #[stable(feature = "vec_from_cow_slice", since = "1.14.0")]
1833 impl<'a
, T
> From
<Cow
<'a
, [T
]>> for Vec
<T
> where [T
]: ToOwned
<Owned
=Vec
<T
>> {
1834 fn from(s
: Cow
<'a
, [T
]>) -> Vec
<T
> {
1839 #[stable(feature = "rust1", since = "1.0.0")]
1840 impl<'a
> From
<&'a
str> for Vec
<u8> {
1841 fn from(s
: &'a
str) -> Vec
<u8> {
1842 From
::from(s
.as_bytes())
1846 ////////////////////////////////////////////////////////////////////////////////
1848 ////////////////////////////////////////////////////////////////////////////////
1850 #[stable(feature = "cow_from_vec", since = "1.7.0")]
1851 impl<'a
, T
: Clone
> From
<&'a
[T
]> for Cow
<'a
, [T
]> {
1852 fn from(s
: &'a
[T
]) -> Cow
<'a
, [T
]> {
1857 #[stable(feature = "cow_from_vec", since = "1.7.0")]
1858 impl<'a
, T
: Clone
> From
<Vec
<T
>> for Cow
<'a
, [T
]> {
1859 fn from(v
: Vec
<T
>) -> Cow
<'a
, [T
]> {
1864 #[stable(feature = "rust1", since = "1.0.0")]
1865 impl<'a
, T
> FromIterator
<T
> for Cow
<'a
, [T
]> where T
: Clone
{
1866 fn from_iter
<I
: IntoIterator
<Item
= T
>>(it
: I
) -> Cow
<'a
, [T
]> {
1867 Cow
::Owned(FromIterator
::from_iter(it
))
1871 ////////////////////////////////////////////////////////////////////////////////
1873 ////////////////////////////////////////////////////////////////////////////////
1875 /// An iterator that moves out of a vector.
1877 /// This `struct` is created by the `into_iter` method on [`Vec`][`Vec`] (provided
1878 /// by the [`IntoIterator`] trait).
1880 /// [`Vec`]: struct.Vec.html
1881 /// [`IntoIterator`]: ../../std/iter/trait.IntoIterator.html
1882 #[stable(feature = "rust1", since = "1.0.0")]
1883 pub struct IntoIter
<T
> {
1890 #[stable(feature = "vec_intoiter_debug", since = "1.13.0")]
1891 impl<T
: fmt
::Debug
> fmt
::Debug
for IntoIter
<T
> {
1892 fn fmt(&self, f
: &mut fmt
::Formatter
) -> fmt
::Result
{
1893 f
.debug_tuple("IntoIter")
1894 .field(&self.as_slice())
1899 impl<T
> IntoIter
<T
> {
1900 /// Returns the remaining items of this iterator as a slice.
1905 /// let vec = vec!['a', 'b', 'c'];
1906 /// let mut into_iter = vec.into_iter();
1907 /// assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']);
1908 /// let _ = into_iter.next().unwrap();
1909 /// assert_eq!(into_iter.as_slice(), &['b', 'c']);
1911 #[stable(feature = "vec_into_iter_as_slice", since = "1.15.0")]
1912 pub fn as_slice(&self) -> &[T
] {
1914 slice
::from_raw_parts(self.ptr
, self.len())
1918 /// Returns the remaining items of this iterator as a mutable slice.
1923 /// let vec = vec!['a', 'b', 'c'];
1924 /// let mut into_iter = vec.into_iter();
1925 /// assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']);
1926 /// into_iter.as_mut_slice()[2] = 'z';
1927 /// assert_eq!(into_iter.next().unwrap(), 'a');
1928 /// assert_eq!(into_iter.next().unwrap(), 'b');
1929 /// assert_eq!(into_iter.next().unwrap(), 'z');
1931 #[stable(feature = "vec_into_iter_as_slice", since = "1.15.0")]
1932 pub fn as_mut_slice(&self) -> &mut [T
] {
1934 slice
::from_raw_parts_mut(self.ptr
as *mut T
, self.len())
1939 #[stable(feature = "rust1", since = "1.0.0")]
1940 unsafe impl<T
: Send
> Send
for IntoIter
<T
> {}
1941 #[stable(feature = "rust1", since = "1.0.0")]
1942 unsafe impl<T
: Sync
> Sync
for IntoIter
<T
> {}
1944 #[stable(feature = "rust1", since = "1.0.0")]
1945 impl<T
> Iterator
for IntoIter
<T
> {
1949 fn next(&mut self) -> Option
<T
> {
1951 if self.ptr
as *const _
== self.end
{
1954 if mem
::size_of
::<T
>() == 0 {
1955 // purposefully don't use 'ptr.offset' because for
1956 // vectors with 0-size elements this would return the
1958 self.ptr
= arith_offset(self.ptr
as *const i8, 1) as *mut T
;
1960 // Use a non-null pointer value
1961 Some(ptr
::read(EMPTY
as *mut T
))
1964 self.ptr
= self.ptr
.offset(1);
1966 Some(ptr
::read(old
))
1973 fn size_hint(&self) -> (usize, Option
<usize>) {
1974 let diff
= (self.end
as usize) - (self.ptr
as usize);
1975 let size
= mem
::size_of
::<T
>();
1982 (exact
, Some(exact
))
1986 fn count(self) -> usize {
1991 #[stable(feature = "rust1", since = "1.0.0")]
1992 impl<T
> DoubleEndedIterator
for IntoIter
<T
> {
1994 fn next_back(&mut self) -> Option
<T
> {
1996 if self.end
== self.ptr
{
1999 if mem
::size_of
::<T
>() == 0 {
2000 // See above for why 'ptr.offset' isn't used
2001 self.end
= arith_offset(self.end
as *const i8, -1) as *mut T
;
2003 // Use a non-null pointer value
2004 Some(ptr
::read(EMPTY
as *mut T
))
2006 self.end
= self.end
.offset(-1);
2008 Some(ptr
::read(self.end
))
2015 #[stable(feature = "rust1", since = "1.0.0")]
2016 impl<T
> ExactSizeIterator
for IntoIter
<T
> {
2017 fn is_empty(&self) -> bool
{
2018 self.ptr
== self.end
2022 #[unstable(feature = "fused", issue = "35602")]
2023 impl<T
> FusedIterator
for IntoIter
<T
> {}
2025 #[unstable(feature = "trusted_len", issue = "37572")]
2026 unsafe impl<T
> TrustedLen
for IntoIter
<T
> {}
2028 #[stable(feature = "vec_into_iter_clone", since = "1.8.0")]
2029 impl<T
: Clone
> Clone
for IntoIter
<T
> {
2030 fn clone(&self) -> IntoIter
<T
> {
2031 self.as_slice().to_owned().into_iter()
2035 #[stable(feature = "rust1", since = "1.0.0")]
2036 impl<T
> Drop
for IntoIter
<T
> {
2037 #[unsafe_destructor_blind_to_params]
2038 fn drop(&mut self) {
2039 // destroy the remaining elements
2040 for _x
in self.by_ref() {}
2042 // RawVec handles deallocation
2043 let _
= unsafe { RawVec::from_raw_parts(*self.buf, self.cap) }
;
2047 /// A draining iterator for `Vec<T>`.
2049 /// This `struct` is created by the [`drain`] method on [`Vec`].
2051 /// [`drain`]: struct.Vec.html#method.drain
2052 /// [`Vec`]: struct.Vec.html
2053 #[stable(feature = "drain", since = "1.6.0")]
2054 pub struct Drain
<'a
, T
: 'a
> {
2055 /// Index of tail to preserve
2059 /// Current remaining range to remove
2060 iter
: slice
::Iter
<'a
, T
>,
2061 vec
: Shared
<Vec
<T
>>,
2064 #[stable(feature = "drain", since = "1.6.0")]
2065 unsafe impl<'a
, T
: Sync
> Sync
for Drain
<'a
, T
> {}
2066 #[stable(feature = "drain", since = "1.6.0")]
2067 unsafe impl<'a
, T
: Send
> Send
for Drain
<'a
, T
> {}
2069 #[stable(feature = "drain", since = "1.6.0")]
2070 impl<'a
, T
> Iterator
for Drain
<'a
, T
> {
2074 fn next(&mut self) -> Option
<T
> {
2075 self.iter
.next().map(|elt
| unsafe { ptr::read(elt as *const _) }
)
2078 fn size_hint(&self) -> (usize, Option
<usize>) {
2079 self.iter
.size_hint()
2083 #[stable(feature = "drain", since = "1.6.0")]
2084 impl<'a
, T
> DoubleEndedIterator
for Drain
<'a
, T
> {
2086 fn next_back(&mut self) -> Option
<T
> {
2087 self.iter
.next_back().map(|elt
| unsafe { ptr::read(elt as *const _) }
)
2091 #[stable(feature = "drain", since = "1.6.0")]
2092 impl<'a
, T
> Drop
for Drain
<'a
, T
> {
2093 fn drop(&mut self) {
2094 // exhaust self first
2095 while let Some(_
) = self.next() {}
2097 if self.tail_len
> 0 {
2099 let source_vec
= &mut **self.vec
;
2100 // memmove back untouched tail, update to new length
2101 let start
= source_vec
.len();
2102 let tail
= self.tail_start
;
2103 let src
= source_vec
.as_ptr().offset(tail
as isize);
2104 let dst
= source_vec
.as_mut_ptr().offset(start
as isize);
2105 ptr
::copy(src
, dst
, self.tail_len
);
2106 source_vec
.set_len(start
+ self.tail_len
);
2113 #[stable(feature = "drain", since = "1.6.0")]
2114 impl<'a
, T
> ExactSizeIterator
for Drain
<'a
, T
> {
2115 fn is_empty(&self) -> bool
{
2116 self.iter
.is_empty()
2120 #[unstable(feature = "fused", issue = "35602")]
2121 impl<'a
, T
> FusedIterator
for Drain
<'a
, T
> {}