080d41391d
fix memory leak when vec::IntoIter panics during drop Fixes https://github.com/rust-lang/rust/issues/69770
2997 lines
95 KiB
Rust
2997 lines
95 KiB
Rust
//! A contiguous growable array type with heap-allocated contents, written
|
||
//! `Vec<T>`.
|
||
//!
|
||
//! Vectors have `O(1)` indexing, amortized `O(1)` push (to the end) and
|
||
//! `O(1)` pop (from the end).
|
||
//!
|
||
//! Vectors ensure they never allocate more than `isize::MAX` bytes.
|
||
//!
|
||
//! # Examples
|
||
//!
|
||
//! You can explicitly create a [`Vec<T>`] with [`new`]:
|
||
//!
|
||
//! ```
|
||
//! let v: Vec<i32> = Vec::new();
|
||
//! ```
|
||
//!
|
||
//! ...or by using the [`vec!`] macro:
|
||
//!
|
||
//! ```
|
||
//! let v: Vec<i32> = vec![];
|
||
//!
|
||
//! let v = vec![1, 2, 3, 4, 5];
|
||
//!
|
||
//! let v = vec![0; 10]; // ten zeroes
|
||
//! ```
|
||
//!
|
||
//! You can [`push`] values onto the end of a vector (which will grow the vector
|
||
//! as needed):
|
||
//!
|
||
//! ```
|
||
//! let mut v = vec![1, 2];
|
||
//!
|
||
//! v.push(3);
|
||
//! ```
|
||
//!
|
||
//! Popping values works in much the same way:
|
||
//!
|
||
//! ```
|
||
//! let mut v = vec![1, 2];
|
||
//!
|
||
//! let two = v.pop();
|
||
//! ```
|
||
//!
|
||
//! Vectors also support indexing (through the [`Index`] and [`IndexMut`] traits):
|
||
//!
|
||
//! ```
|
||
//! let mut v = vec![1, 2, 3];
|
||
//! let three = v[2];
|
||
//! v[1] = v[1] + 5;
|
||
//! ```
|
||
//!
|
||
//! [`Vec<T>`]: ../../std/vec/struct.Vec.html
|
||
//! [`new`]: ../../std/vec/struct.Vec.html#method.new
|
||
//! [`push`]: ../../std/vec/struct.Vec.html#method.push
|
||
//! [`Index`]: ../../std/ops/trait.Index.html
|
||
//! [`IndexMut`]: ../../std/ops/trait.IndexMut.html
|
||
//! [`vec!`]: ../../std/macro.vec.html
|
||
|
||
#![stable(feature = "rust1", since = "1.0.0")]
|
||
|
||
use core::array::LengthAtMost32;
|
||
use core::cmp::{self, Ordering};
|
||
use core::fmt;
|
||
use core::hash::{self, Hash};
|
||
use core::intrinsics::{arith_offset, assume};
|
||
use core::iter::{FromIterator, FusedIterator, TrustedLen};
|
||
use core::marker::PhantomData;
|
||
use core::mem;
|
||
use core::ops::Bound::{Excluded, Included, Unbounded};
|
||
use core::ops::{self, Index, IndexMut, RangeBounds};
|
||
use core::ptr::{self, NonNull};
|
||
use core::slice::{self, SliceIndex};
|
||
|
||
use crate::borrow::{Cow, ToOwned};
|
||
use crate::boxed::Box;
|
||
use crate::collections::TryReserveError;
|
||
use crate::raw_vec::RawVec;
|
||
|
||
/// A contiguous growable array type, written `Vec<T>` but pronounced 'vector'.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = Vec::new();
|
||
/// vec.push(1);
|
||
/// vec.push(2);
|
||
///
|
||
/// assert_eq!(vec.len(), 2);
|
||
/// assert_eq!(vec[0], 1);
|
||
///
|
||
/// assert_eq!(vec.pop(), Some(2));
|
||
/// assert_eq!(vec.len(), 1);
|
||
///
|
||
/// vec[0] = 7;
|
||
/// assert_eq!(vec[0], 7);
|
||
///
|
||
/// vec.extend([1, 2, 3].iter().copied());
|
||
///
|
||
/// for x in &vec {
|
||
/// println!("{}", x);
|
||
/// }
|
||
/// assert_eq!(vec, [7, 1, 2, 3]);
|
||
/// ```
|
||
///
|
||
/// The [`vec!`] macro is provided to make initialization more convenient:
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1, 2, 3];
|
||
/// vec.push(4);
|
||
/// assert_eq!(vec, [1, 2, 3, 4]);
|
||
/// ```
|
||
///
|
||
/// It can also initialize each element of a `Vec<T>` with a given value.
|
||
/// This may be more efficient than performing allocation and initialization
|
||
/// in separate steps, especially when initializing a vector of zeros:
|
||
///
|
||
/// ```
|
||
/// let vec = vec![0; 5];
|
||
/// assert_eq!(vec, [0, 0, 0, 0, 0]);
|
||
///
|
||
/// // The following is equivalent, but potentially slower:
|
||
/// let mut vec1 = Vec::with_capacity(5);
|
||
/// vec1.resize(5, 0);
|
||
/// ```
|
||
///
|
||
/// Use a `Vec<T>` as an efficient stack:
|
||
///
|
||
/// ```
|
||
/// let mut stack = Vec::new();
|
||
///
|
||
/// stack.push(1);
|
||
/// stack.push(2);
|
||
/// stack.push(3);
|
||
///
|
||
/// while let Some(top) = stack.pop() {
|
||
/// // Prints 3, 2, 1
|
||
/// println!("{}", top);
|
||
/// }
|
||
/// ```
|
||
///
|
||
/// # Indexing
|
||
///
|
||
/// The `Vec` type allows to access values by index, because it implements the
|
||
/// [`Index`] trait. An example will be more explicit:
|
||
///
|
||
/// ```
|
||
/// let v = vec![0, 2, 4, 6];
|
||
/// println!("{}", v[1]); // it will display '2'
|
||
/// ```
|
||
///
|
||
/// However be careful: if you try to access an index which isn't in the `Vec`,
|
||
/// your software will panic! You cannot do this:
|
||
///
|
||
/// ```should_panic
|
||
/// let v = vec![0, 2, 4, 6];
|
||
/// println!("{}", v[6]); // it will panic!
|
||
/// ```
|
||
///
|
||
/// Use [`get`] and [`get_mut`] if you want to check whether the index is in
|
||
/// the `Vec`.
|
||
///
|
||
/// # Slicing
|
||
///
|
||
/// A `Vec` can be mutable. Slices, on the other hand, are read-only objects.
|
||
/// To get a slice, use `&`. Example:
|
||
///
|
||
/// ```
|
||
/// fn read_slice(slice: &[usize]) {
|
||
/// // ...
|
||
/// }
|
||
///
|
||
/// let v = vec![0, 1];
|
||
/// read_slice(&v);
|
||
///
|
||
/// // ... and that's all!
|
||
/// // you can also do it like this:
|
||
/// let x : &[usize] = &v;
|
||
/// ```
|
||
///
|
||
/// In Rust, it's more common to pass slices as arguments rather than vectors
|
||
/// when you just want to provide read access. The same goes for [`String`] and
|
||
/// [`&str`].
|
||
///
|
||
/// # Capacity and reallocation
|
||
///
|
||
/// The capacity of a vector is the amount of space allocated for any future
|
||
/// elements that will be added onto the vector. This is not to be confused with
|
||
/// the *length* of a vector, which specifies the number of actual elements
|
||
/// within the vector. If a vector's length exceeds its capacity, its capacity
|
||
/// will automatically be increased, but its elements will have to be
|
||
/// reallocated.
|
||
///
|
||
/// For example, a vector with capacity 10 and length 0 would be an empty vector
|
||
/// with space for 10 more elements. Pushing 10 or fewer elements onto the
|
||
/// vector will not change its capacity or cause reallocation to occur. However,
|
||
/// if the vector's length is increased to 11, it will have to reallocate, which
|
||
/// can be slow. For this reason, it is recommended to use [`Vec::with_capacity`]
|
||
/// whenever possible to specify how big the vector is expected to get.
|
||
///
|
||
/// # Guarantees
|
||
///
|
||
/// Due to its incredibly fundamental nature, `Vec` makes a lot of guarantees
|
||
/// about its design. This ensures that it's as low-overhead as possible in
|
||
/// the general case, and can be correctly manipulated in primitive ways
|
||
/// by unsafe code. Note that these guarantees refer to an unqualified `Vec<T>`.
|
||
/// If additional type parameters are added (e.g., to support custom allocators),
|
||
/// overriding their defaults may change the behavior.
|
||
///
|
||
/// Most fundamentally, `Vec` is and always will be a (pointer, capacity, length)
|
||
/// triplet. No more, no less. The order of these fields is completely
|
||
/// unspecified, and you should use the appropriate methods to modify these.
|
||
/// The pointer will never be null, so this type is null-pointer-optimized.
|
||
///
|
||
/// However, the pointer may not actually point to allocated memory. In particular,
|
||
/// if you construct a `Vec` with capacity 0 via [`Vec::new`], [`vec![]`][`vec!`],
|
||
/// [`Vec::with_capacity(0)`][`Vec::with_capacity`], or by calling [`shrink_to_fit`]
|
||
/// on an empty Vec, it will not allocate memory. Similarly, if you store zero-sized
|
||
/// types inside a `Vec`, it will not allocate space for them. *Note that in this case
|
||
/// the `Vec` may not report a [`capacity`] of 0*. `Vec` will allocate if and only
|
||
/// if [`mem::size_of::<T>`]`() * capacity() > 0`. In general, `Vec`'s allocation
|
||
/// details are very subtle — if you intend to allocate memory using a `Vec`
|
||
/// and use it for something else (either to pass to unsafe code, or to build your
|
||
/// own memory-backed collection), be sure to deallocate this memory by using
|
||
/// `from_raw_parts` to recover the `Vec` and then dropping it.
|
||
///
|
||
/// If a `Vec` *has* allocated memory, then the memory it points to is on the heap
|
||
/// (as defined by the allocator Rust is configured to use by default), and its
|
||
/// pointer points to [`len`] initialized, contiguous elements in order (what
|
||
/// you would see if you coerced it to a slice), followed by [`capacity`]` -
|
||
/// `[`len`] logically uninitialized, contiguous elements.
|
||
///
|
||
/// `Vec` will never perform a "small optimization" where elements are actually
|
||
/// stored on the stack for two reasons:
|
||
///
|
||
/// * It would make it more difficult for unsafe code to correctly manipulate
|
||
/// a `Vec`. The contents of a `Vec` wouldn't have a stable address if it were
|
||
/// only moved, and it would be more difficult to determine if a `Vec` had
|
||
/// actually allocated memory.
|
||
///
|
||
/// * It would penalize the general case, incurring an additional branch
|
||
/// on every access.
|
||
///
|
||
/// `Vec` will never automatically shrink itself, even if completely empty. This
|
||
/// ensures no unnecessary allocations or deallocations occur. Emptying a `Vec`
|
||
/// and then filling it back up to the same [`len`] should incur no calls to
|
||
/// the allocator. If you wish to free up unused memory, use
|
||
/// [`shrink_to_fit`].
|
||
///
|
||
/// [`push`] and [`insert`] will never (re)allocate if the reported capacity is
|
||
/// sufficient. [`push`] and [`insert`] *will* (re)allocate if
|
||
/// [`len`]` == `[`capacity`]. That is, the reported capacity is completely
|
||
/// accurate, and can be relied on. It can even be used to manually free the memory
|
||
/// allocated by a `Vec` if desired. Bulk insertion methods *may* reallocate, even
|
||
/// when not necessary.
|
||
///
|
||
/// `Vec` does not guarantee any particular growth strategy when reallocating
|
||
/// when full, nor when [`reserve`] is called. The current strategy is basic
|
||
/// and it may prove desirable to use a non-constant growth factor. Whatever
|
||
/// strategy is used will of course guarantee `O(1)` amortized [`push`].
|
||
///
|
||
/// `vec![x; n]`, `vec![a, b, c, d]`, and
|
||
/// [`Vec::with_capacity(n)`][`Vec::with_capacity`], will all produce a `Vec`
|
||
/// with exactly the requested capacity. If [`len`]` == `[`capacity`],
|
||
/// (as is the case for the [`vec!`] macro), then a `Vec<T>` can be converted to
|
||
/// and from a [`Box<[T]>`][owned slice] without reallocating or moving the elements.
|
||
///
|
||
/// `Vec` will not specifically overwrite any data that is removed from it,
|
||
/// but also won't specifically preserve it. Its uninitialized memory is
|
||
/// scratch space that it may use however it wants. It will generally just do
|
||
/// whatever is most efficient or otherwise easy to implement. Do not rely on
|
||
/// removed data to be erased for security purposes. Even if you drop a `Vec`, its
|
||
/// buffer may simply be reused by another `Vec`. Even if you zero a `Vec`'s memory
|
||
/// first, that may not actually happen because the optimizer does not consider
|
||
/// this a side-effect that must be preserved. There is one case which we will
|
||
/// not break, however: using `unsafe` code to write to the excess capacity,
|
||
/// and then increasing the length to match, is always valid.
|
||
///
|
||
/// `Vec` does not currently guarantee the order in which elements are dropped.
|
||
/// The order has changed in the past and may change again.
|
||
///
|
||
/// [`vec!`]: ../../std/macro.vec.html
|
||
/// [`get`]: ../../std/vec/struct.Vec.html#method.get
|
||
/// [`get_mut`]: ../../std/vec/struct.Vec.html#method.get_mut
|
||
/// [`Index`]: ../../std/ops/trait.Index.html
|
||
/// [`String`]: ../../std/string/struct.String.html
|
||
/// [`&str`]: ../../std/primitive.str.html
|
||
/// [`Vec::with_capacity`]: ../../std/vec/struct.Vec.html#method.with_capacity
|
||
/// [`Vec::new`]: ../../std/vec/struct.Vec.html#method.new
|
||
/// [`shrink_to_fit`]: ../../std/vec/struct.Vec.html#method.shrink_to_fit
|
||
/// [`capacity`]: ../../std/vec/struct.Vec.html#method.capacity
|
||
/// [`mem::size_of::<T>`]: ../../std/mem/fn.size_of.html
|
||
/// [`len`]: ../../std/vec/struct.Vec.html#method.len
|
||
/// [`push`]: ../../std/vec/struct.Vec.html#method.push
|
||
/// [`insert`]: ../../std/vec/struct.Vec.html#method.insert
|
||
/// [`reserve`]: ../../std/vec/struct.Vec.html#method.reserve
|
||
/// [owned slice]: ../../std/boxed/struct.Box.html
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[cfg_attr(not(test), rustc_diagnostic_item = "vec_type")]
|
||
pub struct Vec<T> {
|
||
buf: RawVec<T>,
|
||
len: usize,
|
||
}
|
||
|
||
////////////////////////////////////////////////////////////////////////////////
|
||
// Inherent methods
|
||
////////////////////////////////////////////////////////////////////////////////
|
||
|
||
impl<T> Vec<T> {
|
||
/// Constructs a new, empty `Vec<T>`.
|
||
///
|
||
/// The vector will not allocate until elements are pushed onto it.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// # #![allow(unused_mut)]
|
||
/// let mut vec: Vec<i32> = Vec::new();
|
||
/// ```
|
||
#[inline]
|
||
#[rustc_const_stable(feature = "const_vec_new", since = "1.39.0")]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub const fn new() -> Vec<T> {
|
||
Vec { buf: RawVec::NEW, len: 0 }
|
||
}
|
||
|
||
/// Constructs a new, empty `Vec<T>` with the specified capacity.
|
||
///
|
||
/// The vector will be able to hold exactly `capacity` elements without
|
||
/// reallocating. If `capacity` is 0, the vector will not allocate.
|
||
///
|
||
/// It is important to note that although the returned vector has the
|
||
/// *capacity* specified, the vector will have a zero *length*. For an
|
||
/// explanation of the difference between length and capacity, see
|
||
/// *[Capacity and reallocation]*.
|
||
///
|
||
/// [Capacity and reallocation]: #capacity-and-reallocation
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = Vec::with_capacity(10);
|
||
///
|
||
/// // The vector contains no items, even though it has capacity for more
|
||
/// assert_eq!(vec.len(), 0);
|
||
///
|
||
/// // These are all done without reallocating...
|
||
/// for i in 0..10 {
|
||
/// vec.push(i);
|
||
/// }
|
||
///
|
||
/// // ...but this may make the vector reallocate
|
||
/// vec.push(11);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn with_capacity(capacity: usize) -> Vec<T> {
|
||
Vec { buf: RawVec::with_capacity(capacity), len: 0 }
|
||
}
|
||
|
||
/// Decomposes a `Vec<T>` into its raw components.
|
||
///
|
||
/// Returns the raw pointer to the underlying data, the length of
|
||
/// the vector (in elements), and the allocated capacity of the
|
||
/// data (in elements). These are the same arguments in the same
|
||
/// order as the arguments to [`from_raw_parts`].
|
||
///
|
||
/// After calling this function, the caller is responsible for the
|
||
/// memory previously managed by the `Vec`. The only way to do
|
||
/// this is to convert the raw pointer, length, and capacity back
|
||
/// into a `Vec` with the [`from_raw_parts`] function, allowing
|
||
/// the destructor to perform the cleanup.
|
||
///
|
||
/// [`from_raw_parts`]: #method.from_raw_parts
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// #![feature(vec_into_raw_parts)]
|
||
/// let v: Vec<i32> = vec![-1, 0, 1];
|
||
///
|
||
/// let (ptr, len, cap) = v.into_raw_parts();
|
||
///
|
||
/// let rebuilt = unsafe {
|
||
/// // We can now make changes to the components, such as
|
||
/// // transmuting the raw pointer to a compatible type.
|
||
/// let ptr = ptr as *mut u32;
|
||
///
|
||
/// Vec::from_raw_parts(ptr, len, cap)
|
||
/// };
|
||
/// assert_eq!(rebuilt, [4294967295, 0, 1]);
|
||
/// ```
|
||
#[unstable(feature = "vec_into_raw_parts", reason = "new API", issue = "65816")]
|
||
pub fn into_raw_parts(self) -> (*mut T, usize, usize) {
|
||
let mut me = mem::ManuallyDrop::new(self);
|
||
(me.as_mut_ptr(), me.len(), me.capacity())
|
||
}
|
||
|
||
/// Creates a `Vec<T>` directly from the raw components of another vector.
|
||
///
|
||
/// # Safety
|
||
///
|
||
/// This is highly unsafe, due to the number of invariants that aren't
|
||
/// checked:
|
||
///
|
||
/// * `ptr` needs to have been previously allocated via [`String`]/`Vec<T>`
|
||
/// (at least, it's highly likely to be incorrect if it wasn't).
|
||
/// * `T` needs to have the same size and alignment as what `ptr` was allocated with.
|
||
/// (`T` having a less strict alignment is not sufficient, the alignment really
|
||
/// needs to be equal to satsify the [`dealloc`] requirement that memory must be
|
||
/// allocated and deallocated with the same layout.)
|
||
/// * `length` needs to be less than or equal to `capacity`.
|
||
/// * `capacity` needs to be the capacity that the pointer was allocated with.
|
||
///
|
||
/// Violating these may cause problems like corrupting the allocator's
|
||
/// internal data structures. For example it is **not** safe
|
||
/// to build a `Vec<u8>` from a pointer to a C `char` array with length `size_t`.
|
||
/// It's also not safe to build one from a `Vec<u16>` and its length, because
|
||
/// the allocator cares about the alignment, and these two types have different
|
||
/// alignments. The buffer was allocated with alignment 2 (for `u16`), but after
|
||
/// turning it into a `Vec<u8>` it'll be deallocated with alignment 1.
|
||
///
|
||
/// The ownership of `ptr` is effectively transferred to the
|
||
/// `Vec<T>` which may then deallocate, reallocate or change the
|
||
/// contents of memory pointed to by the pointer at will. Ensure
|
||
/// that nothing else uses the pointer after calling this
|
||
/// function.
|
||
///
|
||
/// [`String`]: ../../std/string/struct.String.html
|
||
/// [`dealloc`]: ../../alloc/alloc/trait.GlobalAlloc.html#tymethod.dealloc
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// use std::ptr;
|
||
/// use std::mem;
|
||
///
|
||
/// let v = vec![1, 2, 3];
|
||
///
|
||
// FIXME Update this when vec_into_raw_parts is stabilized
|
||
/// // Prevent running `v`'s destructor so we are in complete control
|
||
/// // of the allocation.
|
||
/// let mut v = mem::ManuallyDrop::new(v);
|
||
///
|
||
/// // Pull out the various important pieces of information about `v`
|
||
/// let p = v.as_mut_ptr();
|
||
/// let len = v.len();
|
||
/// let cap = v.capacity();
|
||
///
|
||
/// unsafe {
|
||
/// // Overwrite memory with 4, 5, 6
|
||
/// for i in 0..len as isize {
|
||
/// ptr::write(p.offset(i), 4 + i);
|
||
/// }
|
||
///
|
||
/// // Put everything back together into a Vec
|
||
/// let rebuilt = Vec::from_raw_parts(p, len, cap);
|
||
/// assert_eq!(rebuilt, [4, 5, 6]);
|
||
/// }
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub unsafe fn from_raw_parts(ptr: *mut T, length: usize, capacity: usize) -> Vec<T> {
|
||
Vec { buf: RawVec::from_raw_parts(ptr, capacity), len: length }
|
||
}
|
||
|
||
/// Returns the number of elements the vector can hold without
|
||
/// reallocating.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let vec: Vec<i32> = Vec::with_capacity(10);
|
||
/// assert_eq!(vec.capacity(), 10);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn capacity(&self) -> usize {
|
||
self.buf.capacity()
|
||
}
|
||
|
||
/// Reserves capacity for at least `additional` more elements to be inserted
|
||
/// in the given `Vec<T>`. The collection may reserve more space to avoid
|
||
/// frequent reallocations. After calling `reserve`, capacity will be
|
||
/// greater than or equal to `self.len() + additional`. Does nothing if
|
||
/// capacity is already sufficient.
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if the new capacity overflows `usize`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1];
|
||
/// vec.reserve(10);
|
||
/// assert!(vec.capacity() >= 11);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn reserve(&mut self, additional: usize) {
|
||
self.buf.reserve(self.len, additional);
|
||
}
|
||
|
||
/// Reserves the minimum capacity for exactly `additional` more elements to
|
||
/// be inserted in the given `Vec<T>`. After calling `reserve_exact`,
|
||
/// capacity will be greater than or equal to `self.len() + additional`.
|
||
/// Does nothing if the capacity is already sufficient.
|
||
///
|
||
/// Note that the allocator may give the collection more space than it
|
||
/// requests. Therefore, capacity can not be relied upon to be precisely
|
||
/// minimal. Prefer `reserve` if future insertions are expected.
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if the new capacity overflows `usize`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1];
|
||
/// vec.reserve_exact(10);
|
||
/// assert!(vec.capacity() >= 11);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn reserve_exact(&mut self, additional: usize) {
|
||
self.buf.reserve_exact(self.len, additional);
|
||
}
|
||
|
||
/// Tries to reserve capacity for at least `additional` more elements to be inserted
|
||
/// in the given `Vec<T>`. The collection may reserve more space to avoid
|
||
/// frequent reallocations. After calling `reserve`, capacity will be
|
||
/// greater than or equal to `self.len() + additional`. Does nothing if
|
||
/// capacity is already sufficient.
|
||
///
|
||
/// # Errors
|
||
///
|
||
/// If the capacity overflows, or the allocator reports a failure, then an error
|
||
/// is returned.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// #![feature(try_reserve)]
|
||
/// use std::collections::TryReserveError;
|
||
///
|
||
/// fn process_data(data: &[u32]) -> Result<Vec<u32>, TryReserveError> {
|
||
/// let mut output = Vec::new();
|
||
///
|
||
/// // Pre-reserve the memory, exiting if we can't
|
||
/// output.try_reserve(data.len())?;
|
||
///
|
||
/// // Now we know this can't OOM in the middle of our complex work
|
||
/// output.extend(data.iter().map(|&val| {
|
||
/// val * 2 + 5 // very complicated
|
||
/// }));
|
||
///
|
||
/// Ok(output)
|
||
/// }
|
||
/// # process_data(&[1, 2, 3]).expect("why is the test harness OOMing on 12 bytes?");
|
||
/// ```
|
||
#[unstable(feature = "try_reserve", reason = "new API", issue = "48043")]
|
||
pub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError> {
|
||
self.buf.try_reserve(self.len, additional)
|
||
}
|
||
|
||
/// Tries to reserves the minimum capacity for exactly `additional` more elements to
|
||
/// be inserted in the given `Vec<T>`. After calling `reserve_exact`,
|
||
/// capacity will be greater than or equal to `self.len() + additional`.
|
||
/// Does nothing if the capacity is already sufficient.
|
||
///
|
||
/// Note that the allocator may give the collection more space than it
|
||
/// requests. Therefore, capacity can not be relied upon to be precisely
|
||
/// minimal. Prefer `reserve` if future insertions are expected.
|
||
///
|
||
/// # Errors
|
||
///
|
||
/// If the capacity overflows, or the allocator reports a failure, then an error
|
||
/// is returned.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// #![feature(try_reserve)]
|
||
/// use std::collections::TryReserveError;
|
||
///
|
||
/// fn process_data(data: &[u32]) -> Result<Vec<u32>, TryReserveError> {
|
||
/// let mut output = Vec::new();
|
||
///
|
||
/// // Pre-reserve the memory, exiting if we can't
|
||
/// output.try_reserve(data.len())?;
|
||
///
|
||
/// // Now we know this can't OOM in the middle of our complex work
|
||
/// output.extend(data.iter().map(|&val| {
|
||
/// val * 2 + 5 // very complicated
|
||
/// }));
|
||
///
|
||
/// Ok(output)
|
||
/// }
|
||
/// # process_data(&[1, 2, 3]).expect("why is the test harness OOMing on 12 bytes?");
|
||
/// ```
|
||
#[unstable(feature = "try_reserve", reason = "new API", issue = "48043")]
|
||
pub fn try_reserve_exact(&mut self, additional: usize) -> Result<(), TryReserveError> {
|
||
self.buf.try_reserve_exact(self.len, additional)
|
||
}
|
||
|
||
/// Shrinks the capacity of the vector as much as possible.
|
||
///
|
||
/// It will drop down as close as possible to the length but the allocator
|
||
/// may still inform the vector that there is space for a few more elements.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = Vec::with_capacity(10);
|
||
/// vec.extend([1, 2, 3].iter().cloned());
|
||
/// assert_eq!(vec.capacity(), 10);
|
||
/// vec.shrink_to_fit();
|
||
/// assert!(vec.capacity() >= 3);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn shrink_to_fit(&mut self) {
|
||
if self.capacity() != self.len {
|
||
self.buf.shrink_to_fit(self.len);
|
||
}
|
||
}
|
||
|
||
/// Shrinks the capacity of the vector with a lower bound.
|
||
///
|
||
/// The capacity will remain at least as large as both the length
|
||
/// and the supplied value.
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if the current capacity is smaller than the supplied
|
||
/// minimum capacity.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// #![feature(shrink_to)]
|
||
/// let mut vec = Vec::with_capacity(10);
|
||
/// vec.extend([1, 2, 3].iter().cloned());
|
||
/// assert_eq!(vec.capacity(), 10);
|
||
/// vec.shrink_to(4);
|
||
/// assert!(vec.capacity() >= 4);
|
||
/// vec.shrink_to(0);
|
||
/// assert!(vec.capacity() >= 3);
|
||
/// ```
|
||
#[unstable(feature = "shrink_to", reason = "new API", issue = "56431")]
|
||
pub fn shrink_to(&mut self, min_capacity: usize) {
|
||
self.buf.shrink_to_fit(cmp::max(self.len, min_capacity));
|
||
}
|
||
|
||
/// Converts the vector into [`Box<[T]>`][owned slice].
|
||
///
|
||
/// Note that this will drop any excess capacity.
|
||
///
|
||
/// [owned slice]: ../../std/boxed/struct.Box.html
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let v = vec![1, 2, 3];
|
||
///
|
||
/// let slice = v.into_boxed_slice();
|
||
/// ```
|
||
///
|
||
/// Any excess capacity is removed:
|
||
///
|
||
/// ```
|
||
/// let mut vec = Vec::with_capacity(10);
|
||
/// vec.extend([1, 2, 3].iter().cloned());
|
||
///
|
||
/// assert_eq!(vec.capacity(), 10);
|
||
/// let slice = vec.into_boxed_slice();
|
||
/// assert_eq!(slice.into_vec().capacity(), 3);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn into_boxed_slice(mut self) -> Box<[T]> {
|
||
unsafe {
|
||
self.shrink_to_fit();
|
||
let buf = ptr::read(&self.buf);
|
||
mem::forget(self);
|
||
buf.into_box()
|
||
}
|
||
}
|
||
|
||
/// Shortens the vector, keeping the first `len` elements and dropping
|
||
/// the rest.
|
||
///
|
||
/// If `len` is greater than the vector's current length, this has no
|
||
/// effect.
|
||
///
|
||
/// The [`drain`] method can emulate `truncate`, but causes the excess
|
||
/// elements to be returned instead of dropped.
|
||
///
|
||
/// Note that this method has no effect on the allocated capacity
|
||
/// of the vector.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Truncating a five element vector to two elements:
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1, 2, 3, 4, 5];
|
||
/// vec.truncate(2);
|
||
/// assert_eq!(vec, [1, 2]);
|
||
/// ```
|
||
///
|
||
/// No truncation occurs when `len` is greater than the vector's current
|
||
/// length:
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1, 2, 3];
|
||
/// vec.truncate(8);
|
||
/// assert_eq!(vec, [1, 2, 3]);
|
||
/// ```
|
||
///
|
||
/// Truncating when `len == 0` is equivalent to calling the [`clear`]
|
||
/// method.
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1, 2, 3];
|
||
/// vec.truncate(0);
|
||
/// assert_eq!(vec, []);
|
||
/// ```
|
||
///
|
||
/// [`clear`]: #method.clear
|
||
/// [`drain`]: #method.drain
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn truncate(&mut self, len: usize) {
|
||
// This is safe because:
|
||
//
|
||
// * the slice passed to `drop_in_place` is valid; the `len > self.len`
|
||
// case avoids creating an invalid slice, and
|
||
// * the `len` of the vector is shrunk before calling `drop_in_place`,
|
||
// such that no value will be dropped twice in case `drop_in_place`
|
||
// were to panic once (if it panics twice, the program aborts).
|
||
unsafe {
|
||
if len > self.len {
|
||
return;
|
||
}
|
||
let s = self.get_unchecked_mut(len..) as *mut _;
|
||
self.len = len;
|
||
ptr::drop_in_place(s);
|
||
}
|
||
}
|
||
|
||
/// Extracts a slice containing the entire vector.
|
||
///
|
||
/// Equivalent to `&s[..]`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// use std::io::{self, Write};
|
||
/// let buffer = vec![1, 2, 3, 5, 8];
|
||
/// io::sink().write(buffer.as_slice()).unwrap();
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "vec_as_slice", since = "1.7.0")]
|
||
pub fn as_slice(&self) -> &[T] {
|
||
self
|
||
}
|
||
|
||
/// Extracts a mutable slice of the entire vector.
|
||
///
|
||
/// Equivalent to `&mut s[..]`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// use std::io::{self, Read};
|
||
/// let mut buffer = vec![0; 3];
|
||
/// io::repeat(0b101).read_exact(buffer.as_mut_slice()).unwrap();
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "vec_as_slice", since = "1.7.0")]
|
||
pub fn as_mut_slice(&mut self) -> &mut [T] {
|
||
self
|
||
}
|
||
|
||
/// Returns a raw pointer to the vector's buffer.
|
||
///
|
||
/// The caller must ensure that the vector outlives the pointer this
|
||
/// function returns, or else it will end up pointing to garbage.
|
||
/// Modifying the vector may cause its buffer to be reallocated,
|
||
/// which would also make any pointers to it invalid.
|
||
///
|
||
/// The caller must also ensure that the memory the pointer (non-transitively) points to
|
||
/// is never written to (except inside an `UnsafeCell`) using this pointer or any pointer
|
||
/// derived from it. If you need to mutate the contents of the slice, use [`as_mut_ptr`].
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let x = vec![1, 2, 4];
|
||
/// let x_ptr = x.as_ptr();
|
||
///
|
||
/// unsafe {
|
||
/// for i in 0..x.len() {
|
||
/// assert_eq!(*x_ptr.add(i), 1 << i);
|
||
/// }
|
||
/// }
|
||
/// ```
|
||
///
|
||
/// [`as_mut_ptr`]: #method.as_mut_ptr
|
||
#[stable(feature = "vec_as_ptr", since = "1.37.0")]
|
||
#[inline]
|
||
pub fn as_ptr(&self) -> *const T {
|
||
// We shadow the slice method of the same name to avoid going through
|
||
// `deref`, which creates an intermediate reference.
|
||
let ptr = self.buf.ptr();
|
||
unsafe {
|
||
assume(!ptr.is_null());
|
||
}
|
||
ptr
|
||
}
|
||
|
||
/// Returns an unsafe mutable pointer to the vector's buffer.
|
||
///
|
||
/// The caller must ensure that the vector outlives the pointer this
|
||
/// function returns, or else it will end up pointing to garbage.
|
||
/// Modifying the vector may cause its buffer to be reallocated,
|
||
/// which would also make any pointers to it invalid.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// // Allocate vector big enough for 4 elements.
|
||
/// let size = 4;
|
||
/// let mut x: Vec<i32> = Vec::with_capacity(size);
|
||
/// let x_ptr = x.as_mut_ptr();
|
||
///
|
||
/// // Initialize elements via raw pointer writes, then set length.
|
||
/// unsafe {
|
||
/// for i in 0..size {
|
||
/// *x_ptr.add(i) = i as i32;
|
||
/// }
|
||
/// x.set_len(size);
|
||
/// }
|
||
/// assert_eq!(&*x, &[0,1,2,3]);
|
||
/// ```
|
||
#[stable(feature = "vec_as_ptr", since = "1.37.0")]
|
||
#[inline]
|
||
pub fn as_mut_ptr(&mut self) -> *mut T {
|
||
// We shadow the slice method of the same name to avoid going through
|
||
// `deref_mut`, which creates an intermediate reference.
|
||
let ptr = self.buf.ptr();
|
||
unsafe {
|
||
assume(!ptr.is_null());
|
||
}
|
||
ptr
|
||
}
|
||
|
||
/// Forces the length of the vector to `new_len`.
|
||
///
|
||
/// This is a low-level operation that maintains none of the normal
|
||
/// invariants of the type. Normally changing the length of a vector
|
||
/// is done using one of the safe operations instead, such as
|
||
/// [`truncate`], [`resize`], [`extend`], or [`clear`].
|
||
///
|
||
/// [`truncate`]: #method.truncate
|
||
/// [`resize`]: #method.resize
|
||
/// [`extend`]: ../../std/iter/trait.Extend.html#tymethod.extend
|
||
/// [`clear`]: #method.clear
|
||
///
|
||
/// # Safety
|
||
///
|
||
/// - `new_len` must be less than or equal to [`capacity()`].
|
||
/// - The elements at `old_len..new_len` must be initialized.
|
||
///
|
||
/// [`capacity()`]: #method.capacity
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// This method can be useful for situations in which the vector
|
||
/// is serving as a buffer for other code, particularly over FFI:
|
||
///
|
||
/// ```no_run
|
||
/// # #![allow(dead_code)]
|
||
/// # // This is just a minimal skeleton for the doc example;
|
||
/// # // don't use this as a starting point for a real library.
|
||
/// # pub struct StreamWrapper { strm: *mut std::ffi::c_void }
|
||
/// # const Z_OK: i32 = 0;
|
||
/// # extern "C" {
|
||
/// # fn deflateGetDictionary(
|
||
/// # strm: *mut std::ffi::c_void,
|
||
/// # dictionary: *mut u8,
|
||
/// # dictLength: *mut usize,
|
||
/// # ) -> i32;
|
||
/// # }
|
||
/// # impl StreamWrapper {
|
||
/// pub fn get_dictionary(&self) -> Option<Vec<u8>> {
|
||
/// // Per the FFI method's docs, "32768 bytes is always enough".
|
||
/// let mut dict = Vec::with_capacity(32_768);
|
||
/// let mut dict_length = 0;
|
||
/// // SAFETY: When `deflateGetDictionary` returns `Z_OK`, it holds that:
|
||
/// // 1. `dict_length` elements were initialized.
|
||
/// // 2. `dict_length` <= the capacity (32_768)
|
||
/// // which makes `set_len` safe to call.
|
||
/// unsafe {
|
||
/// // Make the FFI call...
|
||
/// let r = deflateGetDictionary(self.strm, dict.as_mut_ptr(), &mut dict_length);
|
||
/// if r == Z_OK {
|
||
/// // ...and update the length to what was initialized.
|
||
/// dict.set_len(dict_length);
|
||
/// Some(dict)
|
||
/// } else {
|
||
/// None
|
||
/// }
|
||
/// }
|
||
/// }
|
||
/// # }
|
||
/// ```
|
||
///
|
||
/// While the following example is sound, there is a memory leak since
|
||
/// the inner vectors were not freed prior to the `set_len` call:
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![vec![1, 0, 0],
|
||
/// vec![0, 1, 0],
|
||
/// vec![0, 0, 1]];
|
||
/// // SAFETY:
|
||
/// // 1. `old_len..0` is empty so no elements need to be initialized.
|
||
/// // 2. `0 <= capacity` always holds whatever `capacity` is.
|
||
/// unsafe {
|
||
/// vec.set_len(0);
|
||
/// }
|
||
/// ```
|
||
///
|
||
/// Normally, here, one would use [`clear`] instead to correctly drop
|
||
/// the contents and thus not leak memory.
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub unsafe fn set_len(&mut self, new_len: usize) {
|
||
debug_assert!(new_len <= self.capacity());
|
||
|
||
self.len = new_len;
|
||
}
|
||
|
||
/// Removes an element from the vector and returns it.
|
||
///
|
||
/// The removed element is replaced by the last element of the vector.
|
||
///
|
||
/// This does not preserve ordering, but is O(1).
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if `index` is out of bounds.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut v = vec!["foo", "bar", "baz", "qux"];
|
||
///
|
||
/// assert_eq!(v.swap_remove(1), "bar");
|
||
/// assert_eq!(v, ["foo", "qux", "baz"]);
|
||
///
|
||
/// assert_eq!(v.swap_remove(0), "foo");
|
||
/// assert_eq!(v, ["baz", "qux"]);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn swap_remove(&mut self, index: usize) -> T {
|
||
unsafe {
|
||
// We replace self[index] with the last element. Note that if the
|
||
// bounds check on hole succeeds there must be a last element (which
|
||
// can be self[index] itself).
|
||
let hole: *mut T = &mut self[index];
|
||
let last = ptr::read(self.get_unchecked(self.len - 1));
|
||
self.len -= 1;
|
||
ptr::replace(hole, last)
|
||
}
|
||
}
|
||
|
||
/// Inserts an element at position `index` within the vector, shifting all
|
||
/// elements after it to the right.
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if `index > len`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1, 2, 3];
|
||
/// vec.insert(1, 4);
|
||
/// assert_eq!(vec, [1, 4, 2, 3]);
|
||
/// vec.insert(4, 5);
|
||
/// assert_eq!(vec, [1, 4, 2, 3, 5]);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn insert(&mut self, index: usize, element: T) {
|
||
let len = self.len();
|
||
assert!(index <= len);
|
||
|
||
// space for the new element
|
||
if len == self.buf.capacity() {
|
||
self.reserve(1);
|
||
}
|
||
|
||
unsafe {
|
||
// infallible
|
||
// The spot to put the new value
|
||
{
|
||
let p = self.as_mut_ptr().add(index);
|
||
// Shift everything over to make space. (Duplicating the
|
||
// `index`th element into two consecutive places.)
|
||
ptr::copy(p, p.offset(1), len - index);
|
||
// Write it in, overwriting the first copy of the `index`th
|
||
// element.
|
||
ptr::write(p, element);
|
||
}
|
||
self.set_len(len + 1);
|
||
}
|
||
}
|
||
|
||
/// Removes and returns the element at position `index` within the vector,
|
||
/// shifting all elements after it to the left.
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if `index` is out of bounds.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut v = vec![1, 2, 3];
|
||
/// assert_eq!(v.remove(1), 2);
|
||
/// assert_eq!(v, [1, 3]);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn remove(&mut self, index: usize) -> T {
|
||
let len = self.len();
|
||
assert!(index < len);
|
||
unsafe {
|
||
// infallible
|
||
let ret;
|
||
{
|
||
// the place we are taking from.
|
||
let ptr = self.as_mut_ptr().add(index);
|
||
// copy it out, unsafely having a copy of the value on
|
||
// the stack and in the vector at the same time.
|
||
ret = ptr::read(ptr);
|
||
|
||
// Shift everything down to fill in that spot.
|
||
ptr::copy(ptr.offset(1), ptr, len - index - 1);
|
||
}
|
||
self.set_len(len - 1);
|
||
ret
|
||
}
|
||
}
|
||
|
||
/// Retains only the elements specified by the predicate.
|
||
///
|
||
/// In other words, remove all elements `e` such that `f(&e)` returns `false`.
|
||
/// This method operates in place, visiting each element exactly once in the
|
||
/// original order, and preserves the order of the retained elements.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1, 2, 3, 4];
|
||
/// vec.retain(|&x| x % 2 == 0);
|
||
/// assert_eq!(vec, [2, 4]);
|
||
/// ```
|
||
///
|
||
/// The exact order may be useful for tracking external state, like an index.
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1, 2, 3, 4, 5];
|
||
/// let keep = [false, true, true, false, true];
|
||
/// let mut i = 0;
|
||
/// vec.retain(|_| (keep[i], i += 1).0);
|
||
/// assert_eq!(vec, [2, 3, 5]);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn retain<F>(&mut self, mut f: F)
|
||
where
|
||
F: FnMut(&T) -> bool,
|
||
{
|
||
let len = self.len();
|
||
let mut del = 0;
|
||
{
|
||
let v = &mut **self;
|
||
|
||
for i in 0..len {
|
||
if !f(&v[i]) {
|
||
del += 1;
|
||
} else if del > 0 {
|
||
v.swap(i - del, i);
|
||
}
|
||
}
|
||
}
|
||
if del > 0 {
|
||
self.truncate(len - del);
|
||
}
|
||
}
|
||
|
||
/// Removes all but the first of consecutive elements in the vector that resolve to the same
|
||
/// key.
|
||
///
|
||
/// If the vector is sorted, this removes all duplicates.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![10, 20, 21, 30, 20];
|
||
///
|
||
/// vec.dedup_by_key(|i| *i / 10);
|
||
///
|
||
/// assert_eq!(vec, [10, 20, 30, 20]);
|
||
/// ```
|
||
#[stable(feature = "dedup_by", since = "1.16.0")]
|
||
#[inline]
|
||
pub fn dedup_by_key<F, K>(&mut self, mut key: F)
|
||
where
|
||
F: FnMut(&mut T) -> K,
|
||
K: PartialEq,
|
||
{
|
||
self.dedup_by(|a, b| key(a) == key(b))
|
||
}
|
||
|
||
/// Removes all but the first of consecutive elements in the vector satisfying a given equality
|
||
/// relation.
|
||
///
|
||
/// The `same_bucket` function is passed references to two elements from the vector and
|
||
/// must determine if the elements compare equal. The elements are passed in opposite order
|
||
/// from their order in the slice, so if `same_bucket(a, b)` returns `true`, `a` is removed.
|
||
///
|
||
/// If the vector is sorted, this removes all duplicates.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec!["foo", "bar", "Bar", "baz", "bar"];
|
||
///
|
||
/// vec.dedup_by(|a, b| a.eq_ignore_ascii_case(b));
|
||
///
|
||
/// assert_eq!(vec, ["foo", "bar", "baz", "bar"]);
|
||
/// ```
|
||
#[stable(feature = "dedup_by", since = "1.16.0")]
|
||
pub fn dedup_by<F>(&mut self, same_bucket: F)
|
||
where
|
||
F: FnMut(&mut T, &mut T) -> bool,
|
||
{
|
||
let len = {
|
||
let (dedup, _) = self.as_mut_slice().partition_dedup_by(same_bucket);
|
||
dedup.len()
|
||
};
|
||
self.truncate(len);
|
||
}
|
||
|
||
/// Appends an element to the back of a collection.
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if the number of elements in the vector overflows a `usize`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1, 2];
|
||
/// vec.push(3);
|
||
/// assert_eq!(vec, [1, 2, 3]);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn push(&mut self, value: T) {
|
||
// This will panic or abort if we would allocate > isize::MAX bytes
|
||
// or if the length increment would overflow for zero-sized types.
|
||
if self.len == self.buf.capacity() {
|
||
self.reserve(1);
|
||
}
|
||
unsafe {
|
||
let end = self.as_mut_ptr().add(self.len);
|
||
ptr::write(end, value);
|
||
self.len += 1;
|
||
}
|
||
}
|
||
|
||
/// Removes the last element from a vector and returns it, or [`None`] if it
|
||
/// is empty.
|
||
///
|
||
/// [`None`]: ../../std/option/enum.Option.html#variant.None
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1, 2, 3];
|
||
/// assert_eq!(vec.pop(), Some(3));
|
||
/// assert_eq!(vec, [1, 2]);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn pop(&mut self) -> Option<T> {
|
||
if self.len == 0 {
|
||
None
|
||
} else {
|
||
unsafe {
|
||
self.len -= 1;
|
||
Some(ptr::read(self.get_unchecked(self.len())))
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Moves all the elements of `other` into `Self`, leaving `other` empty.
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if the number of elements in the vector overflows a `usize`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1, 2, 3];
|
||
/// let mut vec2 = vec![4, 5, 6];
|
||
/// vec.append(&mut vec2);
|
||
/// assert_eq!(vec, [1, 2, 3, 4, 5, 6]);
|
||
/// assert_eq!(vec2, []);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "append", since = "1.4.0")]
|
||
pub fn append(&mut self, other: &mut Self) {
|
||
unsafe {
|
||
self.append_elements(other.as_slice() as _);
|
||
other.set_len(0);
|
||
}
|
||
}
|
||
|
||
/// Appends elements to `Self` from other buffer.
|
||
#[inline]
|
||
unsafe fn append_elements(&mut self, other: *const [T]) {
|
||
let count = (*other).len();
|
||
self.reserve(count);
|
||
let len = self.len();
|
||
ptr::copy_nonoverlapping(other as *const T, self.as_mut_ptr().add(len), count);
|
||
self.len += count;
|
||
}
|
||
|
||
/// Creates a draining iterator that removes the specified range in the vector
|
||
/// and yields the removed items.
|
||
///
|
||
/// Note 1: The element range is removed even if the iterator is only
|
||
/// partially consumed or not consumed at all.
|
||
///
|
||
/// Note 2: It is unspecified how many elements are removed from the vector
|
||
/// if the `Drain` value is leaked.
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if the starting point is greater than the end point or if
|
||
/// the end point is greater than the length of the vector.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut v = vec![1, 2, 3];
|
||
/// let u: Vec<_> = v.drain(1..).collect();
|
||
/// assert_eq!(v, &[1]);
|
||
/// assert_eq!(u, &[2, 3]);
|
||
///
|
||
/// // A full range clears the vector
|
||
/// v.drain(..);
|
||
/// assert_eq!(v, &[]);
|
||
/// ```
|
||
#[stable(feature = "drain", since = "1.6.0")]
|
||
pub fn drain<R>(&mut self, range: R) -> Drain<'_, T>
|
||
where
|
||
R: RangeBounds<usize>,
|
||
{
|
||
// Memory safety
|
||
//
|
||
// When the Drain is first created, it shortens the length of
|
||
// the source vector to make sure no uninitialized or moved-from elements
|
||
// are accessible at all if the Drain's destructor never gets to run.
|
||
//
|
||
// Drain will ptr::read out the values to remove.
|
||
// When finished, remaining tail of the vec is copied back to cover
|
||
// the hole, and the vector length is restored to the new length.
|
||
//
|
||
let len = self.len();
|
||
let start = match range.start_bound() {
|
||
Included(&n) => n,
|
||
Excluded(&n) => n + 1,
|
||
Unbounded => 0,
|
||
};
|
||
let end = match range.end_bound() {
|
||
Included(&n) => n + 1,
|
||
Excluded(&n) => n,
|
||
Unbounded => len,
|
||
};
|
||
assert!(start <= end);
|
||
assert!(end <= len);
|
||
|
||
unsafe {
|
||
// set self.vec length's to start, to be safe in case Drain is leaked
|
||
self.set_len(start);
|
||
// Use the borrow in the IterMut to indicate borrowing behavior of the
|
||
// whole Drain iterator (like &mut T).
|
||
let range_slice = slice::from_raw_parts_mut(self.as_mut_ptr().add(start), end - start);
|
||
Drain {
|
||
tail_start: end,
|
||
tail_len: len - end,
|
||
iter: range_slice.iter(),
|
||
vec: NonNull::from(self),
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Clears the vector, removing all values.
|
||
///
|
||
/// Note that this method has no effect on the allocated capacity
|
||
/// of the vector.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut v = vec![1, 2, 3];
|
||
///
|
||
/// v.clear();
|
||
///
|
||
/// assert!(v.is_empty());
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn clear(&mut self) {
|
||
self.truncate(0)
|
||
}
|
||
|
||
/// Returns the number of elements in the vector, also referred to
|
||
/// as its 'length'.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let a = vec![1, 2, 3];
|
||
/// assert_eq!(a.len(), 3);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn len(&self) -> usize {
|
||
self.len
|
||
}
|
||
|
||
/// Returns `true` if the vector contains no elements.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut v = Vec::new();
|
||
/// assert!(v.is_empty());
|
||
///
|
||
/// v.push(1);
|
||
/// assert!(!v.is_empty());
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn is_empty(&self) -> bool {
|
||
self.len() == 0
|
||
}
|
||
|
||
/// Splits the collection into two at the given index.
|
||
///
|
||
/// Returns a newly allocated vector containing the elements in the range
|
||
/// `[at, len)`. After the call, the original vector will be left containing
|
||
/// the elements `[0, at)` with its previous capacity unchanged.
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if `at > len`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1,2,3];
|
||
/// let vec2 = vec.split_off(1);
|
||
/// assert_eq!(vec, [1]);
|
||
/// assert_eq!(vec2, [2, 3]);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "split_off", since = "1.4.0")]
|
||
pub fn split_off(&mut self, at: usize) -> Self {
|
||
assert!(at <= self.len(), "`at` out of bounds");
|
||
|
||
let other_len = self.len - at;
|
||
let mut other = Vec::with_capacity(other_len);
|
||
|
||
// Unsafely `set_len` and copy items to `other`.
|
||
unsafe {
|
||
self.set_len(at);
|
||
other.set_len(other_len);
|
||
|
||
ptr::copy_nonoverlapping(self.as_ptr().add(at), other.as_mut_ptr(), other.len());
|
||
}
|
||
other
|
||
}
|
||
|
||
/// Resizes the `Vec` in-place so that `len` is equal to `new_len`.
|
||
///
|
||
/// If `new_len` is greater than `len`, the `Vec` is extended by the
|
||
/// difference, with each additional slot filled with the result of
|
||
/// calling the closure `f`. The return values from `f` will end up
|
||
/// in the `Vec` in the order they have been generated.
|
||
///
|
||
/// If `new_len` is less than `len`, the `Vec` is simply truncated.
|
||
///
|
||
/// This method uses a closure to create new values on every push. If
|
||
/// you'd rather [`Clone`] a given value, use [`resize`]. If you want
|
||
/// to use the [`Default`] trait to generate values, you can pass
|
||
/// [`Default::default()`] as the second argument.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1, 2, 3];
|
||
/// vec.resize_with(5, Default::default);
|
||
/// assert_eq!(vec, [1, 2, 3, 0, 0]);
|
||
///
|
||
/// let mut vec = vec![];
|
||
/// let mut p = 1;
|
||
/// vec.resize_with(4, || { p *= 2; p });
|
||
/// assert_eq!(vec, [2, 4, 8, 16]);
|
||
/// ```
|
||
///
|
||
/// [`resize`]: #method.resize
|
||
/// [`Clone`]: ../../std/clone/trait.Clone.html
|
||
#[stable(feature = "vec_resize_with", since = "1.33.0")]
|
||
pub fn resize_with<F>(&mut self, new_len: usize, f: F)
|
||
where
|
||
F: FnMut() -> T,
|
||
{
|
||
let len = self.len();
|
||
if new_len > len {
|
||
self.extend_with(new_len - len, ExtendFunc(f));
|
||
} else {
|
||
self.truncate(new_len);
|
||
}
|
||
}
|
||
|
||
/// Consumes and leaks the `Vec`, returning a mutable reference to the contents,
|
||
/// `&'a mut [T]`. Note that the type `T` must outlive the chosen lifetime
|
||
/// `'a`. If the type has only static references, or none at all, then this
|
||
/// may be chosen to be `'static`.
|
||
///
|
||
/// This function is similar to the `leak` function on `Box`.
|
||
///
|
||
/// This function is mainly useful for data that lives for the remainder of
|
||
/// the program's life. Dropping the returned reference will cause a memory
|
||
/// leak.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Simple usage:
|
||
///
|
||
/// ```
|
||
/// #![feature(vec_leak)]
|
||
///
|
||
/// let x = vec![1, 2, 3];
|
||
/// let static_ref: &'static mut [usize] = Vec::leak(x);
|
||
/// static_ref[0] += 1;
|
||
/// assert_eq!(static_ref, &[2, 2, 3]);
|
||
/// ```
|
||
#[unstable(feature = "vec_leak", issue = "62195")]
|
||
#[inline]
|
||
pub fn leak<'a>(vec: Vec<T>) -> &'a mut [T]
|
||
where
|
||
T: 'a, // Technically not needed, but kept to be explicit.
|
||
{
|
||
Box::leak(vec.into_boxed_slice())
|
||
}
|
||
}
|
||
|
||
impl<T: Clone> Vec<T> {
|
||
/// Resizes the `Vec` in-place so that `len` is equal to `new_len`.
|
||
///
|
||
/// If `new_len` is greater than `len`, the `Vec` is extended by the
|
||
/// difference, with each additional slot filled with `value`.
|
||
/// If `new_len` is less than `len`, the `Vec` is simply truncated.
|
||
///
|
||
/// This method requires `T` to implement [`Clone`],
|
||
/// in order to be able to clone the passed value.
|
||
/// If you need more flexibility (or want to rely on [`Default`] instead of
|
||
/// [`Clone`]), use [`resize_with`].
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec!["hello"];
|
||
/// vec.resize(3, "world");
|
||
/// assert_eq!(vec, ["hello", "world", "world"]);
|
||
///
|
||
/// let mut vec = vec![1, 2, 3, 4];
|
||
/// vec.resize(2, 0);
|
||
/// assert_eq!(vec, [1, 2]);
|
||
/// ```
|
||
///
|
||
/// [`Clone`]: ../../std/clone/trait.Clone.html
|
||
/// [`Default`]: ../../std/default/trait.Default.html
|
||
/// [`resize_with`]: #method.resize_with
|
||
#[stable(feature = "vec_resize", since = "1.5.0")]
|
||
pub fn resize(&mut self, new_len: usize, value: T) {
|
||
let len = self.len();
|
||
|
||
if new_len > len {
|
||
self.extend_with(new_len - len, ExtendElement(value))
|
||
} else {
|
||
self.truncate(new_len);
|
||
}
|
||
}
|
||
|
||
/// Clones and appends all elements in a slice to the `Vec`.
|
||
///
|
||
/// Iterates over the slice `other`, clones each element, and then appends
|
||
/// it to this `Vec`. The `other` vector is traversed in-order.
|
||
///
|
||
/// Note that this function is same as [`extend`] except that it is
|
||
/// specialized to work with slices instead. If and when Rust gets
|
||
/// specialization this function will likely be deprecated (but still
|
||
/// available).
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1];
|
||
/// vec.extend_from_slice(&[2, 3, 4]);
|
||
/// assert_eq!(vec, [1, 2, 3, 4]);
|
||
/// ```
|
||
///
|
||
/// [`extend`]: #method.extend
|
||
#[stable(feature = "vec_extend_from_slice", since = "1.6.0")]
|
||
pub fn extend_from_slice(&mut self, other: &[T]) {
|
||
self.spec_extend(other.iter())
|
||
}
|
||
}
|
||
|
||
impl<T: Default> Vec<T> {
|
||
/// Resizes the `Vec` in-place so that `len` is equal to `new_len`.
|
||
///
|
||
/// If `new_len` is greater than `len`, the `Vec` is extended by the
|
||
/// difference, with each additional slot filled with [`Default::default()`].
|
||
/// If `new_len` is less than `len`, the `Vec` is simply truncated.
|
||
///
|
||
/// This method uses [`Default`] to create new values on every push. If
|
||
/// you'd rather [`Clone`] a given value, use [`resize`].
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// # #![allow(deprecated)]
|
||
/// #![feature(vec_resize_default)]
|
||
///
|
||
/// let mut vec = vec![1, 2, 3];
|
||
/// vec.resize_default(5);
|
||
/// assert_eq!(vec, [1, 2, 3, 0, 0]);
|
||
///
|
||
/// let mut vec = vec![1, 2, 3, 4];
|
||
/// vec.resize_default(2);
|
||
/// assert_eq!(vec, [1, 2]);
|
||
/// ```
|
||
///
|
||
/// [`resize`]: #method.resize
|
||
/// [`Default::default()`]: ../../std/default/trait.Default.html#tymethod.default
|
||
/// [`Default`]: ../../std/default/trait.Default.html
|
||
/// [`Clone`]: ../../std/clone/trait.Clone.html
|
||
#[unstable(feature = "vec_resize_default", issue = "41758")]
|
||
#[rustc_deprecated(
|
||
reason = "This is moving towards being removed in favor \
|
||
of `.resize_with(Default::default)`. If you disagree, please comment \
|
||
in the tracking issue.",
|
||
since = "1.33.0"
|
||
)]
|
||
pub fn resize_default(&mut self, new_len: usize) {
|
||
let len = self.len();
|
||
|
||
if new_len > len {
|
||
self.extend_with(new_len - len, ExtendDefault);
|
||
} else {
|
||
self.truncate(new_len);
|
||
}
|
||
}
|
||
}
|
||
|
||
// This code generalises `extend_with_{element,default}`.
|
||
trait ExtendWith<T> {
|
||
fn next(&mut self) -> T;
|
||
fn last(self) -> T;
|
||
}
|
||
|
||
struct ExtendElement<T>(T);
|
||
impl<T: Clone> ExtendWith<T> for ExtendElement<T> {
|
||
fn next(&mut self) -> T {
|
||
self.0.clone()
|
||
}
|
||
fn last(self) -> T {
|
||
self.0
|
||
}
|
||
}
|
||
|
||
struct ExtendDefault;
|
||
impl<T: Default> ExtendWith<T> for ExtendDefault {
|
||
fn next(&mut self) -> T {
|
||
Default::default()
|
||
}
|
||
fn last(self) -> T {
|
||
Default::default()
|
||
}
|
||
}
|
||
|
||
struct ExtendFunc<F>(F);
|
||
impl<T, F: FnMut() -> T> ExtendWith<T> for ExtendFunc<F> {
|
||
fn next(&mut self) -> T {
|
||
(self.0)()
|
||
}
|
||
fn last(mut self) -> T {
|
||
(self.0)()
|
||
}
|
||
}
|
||
|
||
impl<T> Vec<T> {
|
||
/// Extend the vector by `n` values, using the given generator.
|
||
fn extend_with<E: ExtendWith<T>>(&mut self, n: usize, mut value: E) {
|
||
self.reserve(n);
|
||
|
||
unsafe {
|
||
let mut ptr = self.as_mut_ptr().add(self.len());
|
||
// Use SetLenOnDrop to work around bug where compiler
|
||
// may not realize the store through `ptr` through self.set_len()
|
||
// don't alias.
|
||
let mut local_len = SetLenOnDrop::new(&mut self.len);
|
||
|
||
// Write all elements except the last one
|
||
for _ in 1..n {
|
||
ptr::write(ptr, value.next());
|
||
ptr = ptr.offset(1);
|
||
// Increment the length in every step in case next() panics
|
||
local_len.increment_len(1);
|
||
}
|
||
|
||
if n > 0 {
|
||
// We can write the last element directly without cloning needlessly
|
||
ptr::write(ptr, value.last());
|
||
local_len.increment_len(1);
|
||
}
|
||
|
||
// len set by scope guard
|
||
}
|
||
}
|
||
}
|
||
|
||
// Set the length of the vec when the `SetLenOnDrop` value goes out of scope.
|
||
//
|
||
// The idea is: The length field in SetLenOnDrop is a local variable
|
||
// that the optimizer will see does not alias with any stores through the Vec's data
|
||
// pointer. This is a workaround for alias analysis issue #32155
|
||
struct SetLenOnDrop<'a> {
|
||
len: &'a mut usize,
|
||
local_len: usize,
|
||
}
|
||
|
||
impl<'a> SetLenOnDrop<'a> {
|
||
#[inline]
|
||
fn new(len: &'a mut usize) -> Self {
|
||
SetLenOnDrop { local_len: *len, len }
|
||
}
|
||
|
||
#[inline]
|
||
fn increment_len(&mut self, increment: usize) {
|
||
self.local_len += increment;
|
||
}
|
||
}
|
||
|
||
impl Drop for SetLenOnDrop<'_> {
|
||
#[inline]
|
||
fn drop(&mut self) {
|
||
*self.len = self.local_len;
|
||
}
|
||
}
|
||
|
||
impl<T: PartialEq> Vec<T> {
|
||
/// Removes consecutive repeated elements in the vector according to the
|
||
/// [`PartialEq`] trait implementation.
|
||
///
|
||
/// If the vector is sorted, this removes all duplicates.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1, 2, 2, 3, 2];
|
||
///
|
||
/// vec.dedup();
|
||
///
|
||
/// assert_eq!(vec, [1, 2, 3, 2]);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn dedup(&mut self) {
|
||
self.dedup_by(|a, b| a == b)
|
||
}
|
||
}
|
||
|
||
impl<T> Vec<T> {
|
||
/// Removes the first instance of `item` from the vector if the item exists.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// # #![feature(vec_remove_item)]
|
||
/// let mut vec = vec![1, 2, 3, 1];
|
||
///
|
||
/// vec.remove_item(&1);
|
||
///
|
||
/// assert_eq!(vec, vec![2, 3, 1]);
|
||
/// ```
|
||
#[unstable(feature = "vec_remove_item", reason = "recently added", issue = "40062")]
|
||
pub fn remove_item<V>(&mut self, item: &V) -> Option<T>
|
||
where
|
||
T: PartialEq<V>,
|
||
{
|
||
let pos = self.iter().position(|x| *x == *item)?;
|
||
Some(self.remove(pos))
|
||
}
|
||
}
|
||
|
||
////////////////////////////////////////////////////////////////////////////////
|
||
// Internal methods and functions
|
||
////////////////////////////////////////////////////////////////////////////////
|
||
|
||
#[doc(hidden)]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn from_elem<T: Clone>(elem: T, n: usize) -> Vec<T> {
|
||
<T as SpecFromElem>::from_elem(elem, n)
|
||
}
|
||
|
||
// Specialization trait used for Vec::from_elem
|
||
trait SpecFromElem: Sized {
|
||
fn from_elem(elem: Self, n: usize) -> Vec<Self>;
|
||
}
|
||
|
||
impl<T: Clone> SpecFromElem for T {
|
||
default fn from_elem(elem: Self, n: usize) -> Vec<Self> {
|
||
let mut v = Vec::with_capacity(n);
|
||
v.extend_with(n, ExtendElement(elem));
|
||
v
|
||
}
|
||
}
|
||
|
||
impl SpecFromElem for u8 {
|
||
#[inline]
|
||
fn from_elem(elem: u8, n: usize) -> Vec<u8> {
|
||
if elem == 0 {
|
||
return Vec { buf: RawVec::with_capacity_zeroed(n), len: n };
|
||
}
|
||
unsafe {
|
||
let mut v = Vec::with_capacity(n);
|
||
ptr::write_bytes(v.as_mut_ptr(), elem, n);
|
||
v.set_len(n);
|
||
v
|
||
}
|
||
}
|
||
}
|
||
|
||
impl<T: Clone + IsZero> SpecFromElem for T {
|
||
#[inline]
|
||
fn from_elem(elem: T, n: usize) -> Vec<T> {
|
||
if elem.is_zero() {
|
||
return Vec { buf: RawVec::with_capacity_zeroed(n), len: n };
|
||
}
|
||
let mut v = Vec::with_capacity(n);
|
||
v.extend_with(n, ExtendElement(elem));
|
||
v
|
||
}
|
||
}
|
||
|
||
unsafe trait IsZero {
|
||
/// Whether this value is zero
|
||
fn is_zero(&self) -> bool;
|
||
}
|
||
|
||
macro_rules! impl_is_zero {
|
||
($t: ty, $is_zero: expr) => {
|
||
unsafe impl IsZero for $t {
|
||
#[inline]
|
||
fn is_zero(&self) -> bool {
|
||
$is_zero(*self)
|
||
}
|
||
}
|
||
};
|
||
}
|
||
|
||
impl_is_zero!(i8, |x| x == 0);
|
||
impl_is_zero!(i16, |x| x == 0);
|
||
impl_is_zero!(i32, |x| x == 0);
|
||
impl_is_zero!(i64, |x| x == 0);
|
||
impl_is_zero!(i128, |x| x == 0);
|
||
impl_is_zero!(isize, |x| x == 0);
|
||
|
||
impl_is_zero!(u16, |x| x == 0);
|
||
impl_is_zero!(u32, |x| x == 0);
|
||
impl_is_zero!(u64, |x| x == 0);
|
||
impl_is_zero!(u128, |x| x == 0);
|
||
impl_is_zero!(usize, |x| x == 0);
|
||
|
||
impl_is_zero!(bool, |x| x == false);
|
||
impl_is_zero!(char, |x| x == '\0');
|
||
|
||
impl_is_zero!(f32, |x: f32| x.to_bits() == 0);
|
||
impl_is_zero!(f64, |x: f64| x.to_bits() == 0);
|
||
|
||
unsafe impl<T> IsZero for *const T {
|
||
#[inline]
|
||
fn is_zero(&self) -> bool {
|
||
(*self).is_null()
|
||
}
|
||
}
|
||
|
||
unsafe impl<T> IsZero for *mut T {
|
||
#[inline]
|
||
fn is_zero(&self) -> bool {
|
||
(*self).is_null()
|
||
}
|
||
}
|
||
|
||
// `Option<&T>`, `Option<&mut T>` and `Option<Box<T>>` are guaranteed to represent `None` as null.
|
||
// For fat pointers, the bytes that would be the pointer metadata in the `Some` variant
|
||
// are padding in the `None` variant, so ignoring them and zero-initializing instead is ok.
|
||
|
||
unsafe impl<T: ?Sized> IsZero for Option<&T> {
|
||
#[inline]
|
||
fn is_zero(&self) -> bool {
|
||
self.is_none()
|
||
}
|
||
}
|
||
|
||
unsafe impl<T: ?Sized> IsZero for Option<&mut T> {
|
||
#[inline]
|
||
fn is_zero(&self) -> bool {
|
||
self.is_none()
|
||
}
|
||
}
|
||
|
||
unsafe impl<T: ?Sized> IsZero for Option<Box<T>> {
|
||
#[inline]
|
||
fn is_zero(&self) -> bool {
|
||
self.is_none()
|
||
}
|
||
}
|
||
|
||
////////////////////////////////////////////////////////////////////////////////
|
||
// Common trait implementations for Vec
|
||
////////////////////////////////////////////////////////////////////////////////
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: Clone> Clone for Vec<T> {
|
||
#[cfg(not(test))]
|
||
fn clone(&self) -> Vec<T> {
|
||
<[T]>::to_vec(&**self)
|
||
}
|
||
|
||
// HACK(japaric): with cfg(test) the inherent `[T]::to_vec` method, which is
|
||
// required for this method definition, is not available. Instead use the
|
||
// `slice::to_vec` function which is only available with cfg(test)
|
||
// NB see the slice::hack module in slice.rs for more information
|
||
#[cfg(test)]
|
||
fn clone(&self) -> Vec<T> {
|
||
crate::slice::to_vec(&**self)
|
||
}
|
||
|
||
fn clone_from(&mut self, other: &Vec<T>) {
|
||
other.as_slice().clone_into(self);
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: Hash> Hash for Vec<T> {
|
||
#[inline]
|
||
fn hash<H: hash::Hasher>(&self, state: &mut H) {
|
||
Hash::hash(&**self, state)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[rustc_on_unimplemented(
|
||
message = "vector indices are of type `usize` or ranges of `usize`",
|
||
label = "vector indices are of type `usize` or ranges of `usize`"
|
||
)]
|
||
impl<T, I: SliceIndex<[T]>> Index<I> for Vec<T> {
|
||
type Output = I::Output;
|
||
|
||
#[inline]
|
||
fn index(&self, index: I) -> &Self::Output {
|
||
Index::index(&**self, index)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[rustc_on_unimplemented(
|
||
message = "vector indices are of type `usize` or ranges of `usize`",
|
||
label = "vector indices are of type `usize` or ranges of `usize`"
|
||
)]
|
||
impl<T, I: SliceIndex<[T]>> IndexMut<I> for Vec<T> {
|
||
#[inline]
|
||
fn index_mut(&mut self, index: I) -> &mut Self::Output {
|
||
IndexMut::index_mut(&mut **self, index)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T> ops::Deref for Vec<T> {
|
||
type Target = [T];
|
||
|
||
fn deref(&self) -> &[T] {
|
||
unsafe { slice::from_raw_parts(self.as_ptr(), self.len) }
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T> ops::DerefMut for Vec<T> {
|
||
fn deref_mut(&mut self) -> &mut [T] {
|
||
unsafe { slice::from_raw_parts_mut(self.as_mut_ptr(), self.len) }
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T> FromIterator<T> for Vec<T> {
|
||
#[inline]
|
||
fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Vec<T> {
|
||
<Self as SpecExtend<T, I::IntoIter>>::from_iter(iter.into_iter())
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T> IntoIterator for Vec<T> {
|
||
type Item = T;
|
||
type IntoIter = IntoIter<T>;
|
||
|
||
/// Creates a consuming iterator, that is, one that moves each value out of
|
||
/// the vector (from start to end). The vector cannot be used after calling
|
||
/// this.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let v = vec!["a".to_string(), "b".to_string()];
|
||
/// for s in v.into_iter() {
|
||
/// // s has type String, not &String
|
||
/// println!("{}", s);
|
||
/// }
|
||
/// ```
|
||
#[inline]
|
||
fn into_iter(mut self) -> IntoIter<T> {
|
||
unsafe {
|
||
let begin = self.as_mut_ptr();
|
||
let end = if mem::size_of::<T>() == 0 {
|
||
arith_offset(begin as *const i8, self.len() as isize) as *const T
|
||
} else {
|
||
begin.add(self.len()) as *const T
|
||
};
|
||
let cap = self.buf.capacity();
|
||
mem::forget(self);
|
||
IntoIter {
|
||
buf: NonNull::new_unchecked(begin),
|
||
phantom: PhantomData,
|
||
cap,
|
||
ptr: begin,
|
||
end,
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<'a, T> IntoIterator for &'a Vec<T> {
|
||
type Item = &'a T;
|
||
type IntoIter = slice::Iter<'a, T>;
|
||
|
||
fn into_iter(self) -> slice::Iter<'a, T> {
|
||
self.iter()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<'a, T> IntoIterator for &'a mut Vec<T> {
|
||
type Item = &'a mut T;
|
||
type IntoIter = slice::IterMut<'a, T>;
|
||
|
||
fn into_iter(self) -> slice::IterMut<'a, T> {
|
||
self.iter_mut()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T> Extend<T> for Vec<T> {
|
||
#[inline]
|
||
fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I) {
|
||
<Self as SpecExtend<T, I::IntoIter>>::spec_extend(self, iter.into_iter())
|
||
}
|
||
}
|
||
|
||
// Specialization trait used for Vec::from_iter and Vec::extend
|
||
trait SpecExtend<T, I> {
|
||
fn from_iter(iter: I) -> Self;
|
||
fn spec_extend(&mut self, iter: I);
|
||
}
|
||
|
||
impl<T, I> SpecExtend<T, I> for Vec<T>
|
||
where
|
||
I: Iterator<Item = T>,
|
||
{
|
||
default fn from_iter(mut iterator: I) -> Self {
|
||
// Unroll the first iteration, as the vector is going to be
|
||
// expanded on this iteration in every case when the iterable is not
|
||
// empty, but the loop in extend_desugared() is not going to see the
|
||
// vector being full in the few subsequent loop iterations.
|
||
// So we get better branch prediction.
|
||
let mut vector = match iterator.next() {
|
||
None => return Vec::new(),
|
||
Some(element) => {
|
||
let (lower, _) = iterator.size_hint();
|
||
let mut vector = Vec::with_capacity(lower.saturating_add(1));
|
||
unsafe {
|
||
ptr::write(vector.get_unchecked_mut(0), element);
|
||
vector.set_len(1);
|
||
}
|
||
vector
|
||
}
|
||
};
|
||
<Vec<T> as SpecExtend<T, I>>::spec_extend(&mut vector, iterator);
|
||
vector
|
||
}
|
||
|
||
default fn spec_extend(&mut self, iter: I) {
|
||
self.extend_desugared(iter)
|
||
}
|
||
}
|
||
|
||
impl<T, I> SpecExtend<T, I> for Vec<T>
|
||
where
|
||
I: TrustedLen<Item = T>,
|
||
{
|
||
default fn from_iter(iterator: I) -> Self {
|
||
let mut vector = Vec::new();
|
||
vector.spec_extend(iterator);
|
||
vector
|
||
}
|
||
|
||
default fn spec_extend(&mut self, iterator: I) {
|
||
// This is the case for a TrustedLen iterator.
|
||
let (low, high) = iterator.size_hint();
|
||
if let Some(high_value) = high {
|
||
debug_assert_eq!(
|
||
low,
|
||
high_value,
|
||
"TrustedLen iterator's size hint is not exact: {:?}",
|
||
(low, high)
|
||
);
|
||
}
|
||
if let Some(additional) = high {
|
||
self.reserve(additional);
|
||
unsafe {
|
||
let mut ptr = self.as_mut_ptr().add(self.len());
|
||
let mut local_len = SetLenOnDrop::new(&mut self.len);
|
||
iterator.for_each(move |element| {
|
||
ptr::write(ptr, element);
|
||
ptr = ptr.offset(1);
|
||
// NB can't overflow since we would have had to alloc the address space
|
||
local_len.increment_len(1);
|
||
});
|
||
}
|
||
} else {
|
||
self.extend_desugared(iterator)
|
||
}
|
||
}
|
||
}
|
||
|
||
impl<T> SpecExtend<T, IntoIter<T>> for Vec<T> {
|
||
fn from_iter(iterator: IntoIter<T>) -> Self {
|
||
// A common case is passing a vector into a function which immediately
|
||
// re-collects into a vector. We can short circuit this if the IntoIter
|
||
// has not been advanced at all.
|
||
if iterator.buf.as_ptr() as *const _ == iterator.ptr {
|
||
unsafe {
|
||
let vec = Vec::from_raw_parts(iterator.buf.as_ptr(), iterator.len(), iterator.cap);
|
||
mem::forget(iterator);
|
||
vec
|
||
}
|
||
} else {
|
||
let mut vector = Vec::new();
|
||
vector.spec_extend(iterator);
|
||
vector
|
||
}
|
||
}
|
||
|
||
fn spec_extend(&mut self, mut iterator: IntoIter<T>) {
|
||
unsafe {
|
||
self.append_elements(iterator.as_slice() as _);
|
||
}
|
||
iterator.ptr = iterator.end;
|
||
}
|
||
}
|
||
|
||
impl<'a, T: 'a, I> SpecExtend<&'a T, I> for Vec<T>
|
||
where
|
||
I: Iterator<Item = &'a T>,
|
||
T: Clone,
|
||
{
|
||
default fn from_iter(iterator: I) -> Self {
|
||
SpecExtend::from_iter(iterator.cloned())
|
||
}
|
||
|
||
default fn spec_extend(&mut self, iterator: I) {
|
||
self.spec_extend(iterator.cloned())
|
||
}
|
||
}
|
||
|
||
impl<'a, T: 'a> SpecExtend<&'a T, slice::Iter<'a, T>> for Vec<T>
|
||
where
|
||
T: Copy,
|
||
{
|
||
fn spec_extend(&mut self, iterator: slice::Iter<'a, T>) {
|
||
let slice = iterator.as_slice();
|
||
self.reserve(slice.len());
|
||
unsafe {
|
||
let len = self.len();
|
||
self.set_len(len + slice.len());
|
||
self.get_unchecked_mut(len..).copy_from_slice(slice);
|
||
}
|
||
}
|
||
}
|
||
|
||
impl<T> Vec<T> {
|
||
fn extend_desugared<I: Iterator<Item = T>>(&mut self, mut iterator: I) {
|
||
// This is the case for a general iterator.
|
||
//
|
||
// This function should be the moral equivalent of:
|
||
//
|
||
// for item in iterator {
|
||
// self.push(item);
|
||
// }
|
||
while let Some(element) = iterator.next() {
|
||
let len = self.len();
|
||
if len == self.capacity() {
|
||
let (lower, _) = iterator.size_hint();
|
||
self.reserve(lower.saturating_add(1));
|
||
}
|
||
unsafe {
|
||
ptr::write(self.get_unchecked_mut(len), element);
|
||
// NB can't overflow since we would have had to alloc the address space
|
||
self.set_len(len + 1);
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Creates a splicing iterator that replaces the specified range in the vector
|
||
/// with the given `replace_with` iterator and yields the removed items.
|
||
/// `replace_with` does not need to be the same length as `range`.
|
||
///
|
||
/// The element range is removed even if the iterator is not consumed until the end.
|
||
///
|
||
/// It is unspecified how many elements are removed from the vector
|
||
/// if the `Splice` value is leaked.
|
||
///
|
||
/// The input iterator `replace_with` is only consumed when the `Splice` value is dropped.
|
||
///
|
||
/// This is optimal if:
|
||
///
|
||
/// * The tail (elements in the vector after `range`) is empty,
|
||
/// * or `replace_with` yields fewer elements than `range`’s length
|
||
/// * or the lower bound of its `size_hint()` is exact.
|
||
///
|
||
/// Otherwise, a temporary vector is allocated and the tail is moved twice.
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if the starting point is greater than the end point or if
|
||
/// the end point is greater than the length of the vector.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut v = vec![1, 2, 3];
|
||
/// let new = [7, 8];
|
||
/// let u: Vec<_> = v.splice(..2, new.iter().cloned()).collect();
|
||
/// assert_eq!(v, &[7, 8, 3]);
|
||
/// assert_eq!(u, &[1, 2]);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "vec_splice", since = "1.21.0")]
|
||
pub fn splice<R, I>(&mut self, range: R, replace_with: I) -> Splice<'_, I::IntoIter>
|
||
where
|
||
R: RangeBounds<usize>,
|
||
I: IntoIterator<Item = T>,
|
||
{
|
||
Splice { drain: self.drain(range), replace_with: replace_with.into_iter() }
|
||
}
|
||
|
||
/// Creates an iterator which uses a closure to determine if an element should be removed.
|
||
///
|
||
/// If the closure returns true, then the element is removed and yielded.
|
||
/// If the closure returns false, the element will remain in the vector and will not be yielded
|
||
/// by the iterator.
|
||
///
|
||
/// Using this method is equivalent to the following code:
|
||
///
|
||
/// ```
|
||
/// # let some_predicate = |x: &mut i32| { *x == 2 || *x == 3 || *x == 6 };
|
||
/// # let mut vec = vec![1, 2, 3, 4, 5, 6];
|
||
/// let mut i = 0;
|
||
/// while i != vec.len() {
|
||
/// if some_predicate(&mut vec[i]) {
|
||
/// let val = vec.remove(i);
|
||
/// // your code here
|
||
/// } else {
|
||
/// i += 1;
|
||
/// }
|
||
/// }
|
||
///
|
||
/// # assert_eq!(vec, vec![1, 4, 5]);
|
||
/// ```
|
||
///
|
||
/// But `drain_filter` is easier to use. `drain_filter` is also more efficient,
|
||
/// because it can backshift the elements of the array in bulk.
|
||
///
|
||
/// Note that `drain_filter` also lets you mutate every element in the filter closure,
|
||
/// regardless of whether you choose to keep or remove it.
|
||
///
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Splitting an array into evens and odds, reusing the original allocation:
|
||
///
|
||
/// ```
|
||
/// #![feature(drain_filter)]
|
||
/// let mut numbers = vec![1, 2, 3, 4, 5, 6, 8, 9, 11, 13, 14, 15];
|
||
///
|
||
/// let evens = numbers.drain_filter(|x| *x % 2 == 0).collect::<Vec<_>>();
|
||
/// let odds = numbers;
|
||
///
|
||
/// assert_eq!(evens, vec![2, 4, 6, 8, 14]);
|
||
/// assert_eq!(odds, vec![1, 3, 5, 9, 11, 13, 15]);
|
||
/// ```
|
||
#[unstable(feature = "drain_filter", reason = "recently added", issue = "43244")]
|
||
pub fn drain_filter<F>(&mut self, filter: F) -> DrainFilter<'_, T, F>
|
||
where
|
||
F: FnMut(&mut T) -> bool,
|
||
{
|
||
let old_len = self.len();
|
||
|
||
// Guard against us getting leaked (leak amplification)
|
||
unsafe {
|
||
self.set_len(0);
|
||
}
|
||
|
||
DrainFilter { vec: self, idx: 0, del: 0, old_len, pred: filter, panic_flag: false }
|
||
}
|
||
}
|
||
|
||
/// Extend implementation that copies elements out of references before pushing them onto the Vec.
|
||
///
|
||
/// This implementation is specialized for slice iterators, where it uses [`copy_from_slice`] to
|
||
/// append the entire slice at once.
|
||
///
|
||
/// [`copy_from_slice`]: ../../std/primitive.slice.html#method.copy_from_slice
|
||
#[stable(feature = "extend_ref", since = "1.2.0")]
|
||
impl<'a, T: 'a + Copy> Extend<&'a T> for Vec<T> {
|
||
fn extend<I: IntoIterator<Item = &'a T>>(&mut self, iter: I) {
|
||
self.spec_extend(iter.into_iter())
|
||
}
|
||
}
|
||
|
||
macro_rules! __impl_slice_eq1 {
|
||
([$($vars:tt)*] $lhs:ty, $rhs:ty, $($constraints:tt)*) => {
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<A, B, $($vars)*> PartialEq<$rhs> for $lhs
|
||
where
|
||
A: PartialEq<B>,
|
||
$($constraints)*
|
||
{
|
||
#[inline]
|
||
fn eq(&self, other: &$rhs) -> bool { self[..] == other[..] }
|
||
#[inline]
|
||
fn ne(&self, other: &$rhs) -> bool { self[..] != other[..] }
|
||
}
|
||
}
|
||
}
|
||
|
||
__impl_slice_eq1! { [] Vec<A>, Vec<B>, }
|
||
__impl_slice_eq1! { [] Vec<A>, &[B], }
|
||
__impl_slice_eq1! { [] Vec<A>, &mut [B], }
|
||
__impl_slice_eq1! { [] Cow<'_, [A]>, &[B], A: Clone }
|
||
__impl_slice_eq1! { [] Cow<'_, [A]>, &mut [B], A: Clone }
|
||
__impl_slice_eq1! { [] Cow<'_, [A]>, Vec<B>, A: Clone }
|
||
__impl_slice_eq1! { [const N: usize] Vec<A>, [B; N], [B; N]: LengthAtMost32 }
|
||
__impl_slice_eq1! { [const N: usize] Vec<A>, &[B; N], [B; N]: LengthAtMost32 }
|
||
|
||
// NOTE: some less important impls are omitted to reduce code bloat
|
||
// FIXME(Centril): Reconsider this?
|
||
//__impl_slice_eq1! { [const N: usize] Vec<A>, &mut [B; N], [B; N]: LengthAtMost32 }
|
||
//__impl_slice_eq1! { [const N: usize] Cow<'a, [A]>, [B; N], [B; N]: LengthAtMost32 }
|
||
//__impl_slice_eq1! { [const N: usize] Cow<'a, [A]>, &[B; N], [B; N]: LengthAtMost32 }
|
||
//__impl_slice_eq1! { [const N: usize] Cow<'a, [A]>, &mut [B; N], [B; N]: LengthAtMost32 }
|
||
|
||
/// Implements comparison of vectors, lexicographically.
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: PartialOrd> PartialOrd for Vec<T> {
|
||
#[inline]
|
||
fn partial_cmp(&self, other: &Vec<T>) -> Option<Ordering> {
|
||
PartialOrd::partial_cmp(&**self, &**other)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: Eq> Eq for Vec<T> {}
|
||
|
||
/// Implements ordering of vectors, lexicographically.
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: Ord> Ord for Vec<T> {
|
||
#[inline]
|
||
fn cmp(&self, other: &Vec<T>) -> Ordering {
|
||
Ord::cmp(&**self, &**other)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
unsafe impl<#[may_dangle] T> Drop for Vec<T> {
|
||
fn drop(&mut self) {
|
||
unsafe {
|
||
// use drop for [T]
|
||
ptr::drop_in_place(&mut self[..]);
|
||
}
|
||
// RawVec handles deallocation
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T> Default for Vec<T> {
|
||
/// Creates an empty `Vec<T>`.
|
||
fn default() -> Vec<T> {
|
||
Vec::new()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: fmt::Debug> fmt::Debug for Vec<T> {
|
||
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
fmt::Debug::fmt(&**self, f)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T> AsRef<Vec<T>> for Vec<T> {
|
||
fn as_ref(&self) -> &Vec<T> {
|
||
self
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "vec_as_mut", since = "1.5.0")]
|
||
impl<T> AsMut<Vec<T>> for Vec<T> {
|
||
fn as_mut(&mut self) -> &mut Vec<T> {
|
||
self
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T> AsRef<[T]> for Vec<T> {
|
||
fn as_ref(&self) -> &[T] {
|
||
self
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "vec_as_mut", since = "1.5.0")]
|
||
impl<T> AsMut<[T]> for Vec<T> {
|
||
fn as_mut(&mut self) -> &mut [T] {
|
||
self
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: Clone> From<&[T]> for Vec<T> {
|
||
#[cfg(not(test))]
|
||
fn from(s: &[T]) -> Vec<T> {
|
||
s.to_vec()
|
||
}
|
||
#[cfg(test)]
|
||
fn from(s: &[T]) -> Vec<T> {
|
||
crate::slice::to_vec(s)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "vec_from_mut", since = "1.19.0")]
|
||
impl<T: Clone> From<&mut [T]> for Vec<T> {
|
||
#[cfg(not(test))]
|
||
fn from(s: &mut [T]) -> Vec<T> {
|
||
s.to_vec()
|
||
}
|
||
#[cfg(test)]
|
||
fn from(s: &mut [T]) -> Vec<T> {
|
||
crate::slice::to_vec(s)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "vec_from_cow_slice", since = "1.14.0")]
|
||
impl<'a, T> From<Cow<'a, [T]>> for Vec<T>
|
||
where
|
||
[T]: ToOwned<Owned = Vec<T>>,
|
||
{
|
||
fn from(s: Cow<'a, [T]>) -> Vec<T> {
|
||
s.into_owned()
|
||
}
|
||
}
|
||
|
||
// note: test pulls in libstd, which causes errors here
|
||
#[cfg(not(test))]
|
||
#[stable(feature = "vec_from_box", since = "1.18.0")]
|
||
impl<T> From<Box<[T]>> for Vec<T> {
|
||
fn from(s: Box<[T]>) -> Vec<T> {
|
||
s.into_vec()
|
||
}
|
||
}
|
||
|
||
// note: test pulls in libstd, which causes errors here
|
||
#[cfg(not(test))]
|
||
#[stable(feature = "box_from_vec", since = "1.20.0")]
|
||
impl<T> From<Vec<T>> for Box<[T]> {
|
||
fn from(v: Vec<T>) -> Box<[T]> {
|
||
v.into_boxed_slice()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl From<&str> for Vec<u8> {
|
||
fn from(s: &str) -> Vec<u8> {
|
||
From::from(s.as_bytes())
|
||
}
|
||
}
|
||
|
||
////////////////////////////////////////////////////////////////////////////////
|
||
// Clone-on-write
|
||
////////////////////////////////////////////////////////////////////////////////
|
||
|
||
#[stable(feature = "cow_from_vec", since = "1.8.0")]
|
||
impl<'a, T: Clone> From<&'a [T]> for Cow<'a, [T]> {
|
||
fn from(s: &'a [T]) -> Cow<'a, [T]> {
|
||
Cow::Borrowed(s)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "cow_from_vec", since = "1.8.0")]
|
||
impl<'a, T: Clone> From<Vec<T>> for Cow<'a, [T]> {
|
||
fn from(v: Vec<T>) -> Cow<'a, [T]> {
|
||
Cow::Owned(v)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "cow_from_vec_ref", since = "1.28.0")]
|
||
impl<'a, T: Clone> From<&'a Vec<T>> for Cow<'a, [T]> {
|
||
fn from(v: &'a Vec<T>) -> Cow<'a, [T]> {
|
||
Cow::Borrowed(v.as_slice())
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<'a, T> FromIterator<T> for Cow<'a, [T]>
|
||
where
|
||
T: Clone,
|
||
{
|
||
fn from_iter<I: IntoIterator<Item = T>>(it: I) -> Cow<'a, [T]> {
|
||
Cow::Owned(FromIterator::from_iter(it))
|
||
}
|
||
}
|
||
|
||
////////////////////////////////////////////////////////////////////////////////
|
||
// Iterators
|
||
////////////////////////////////////////////////////////////////////////////////
|
||
|
||
/// An iterator that moves out of a vector.
|
||
///
|
||
/// This `struct` is created by the `into_iter` method on [`Vec`] (provided
|
||
/// by the [`IntoIterator`] trait).
|
||
///
|
||
/// [`Vec`]: struct.Vec.html
|
||
/// [`IntoIterator`]: ../../std/iter/trait.IntoIterator.html
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub struct IntoIter<T> {
|
||
buf: NonNull<T>,
|
||
phantom: PhantomData<T>,
|
||
cap: usize,
|
||
ptr: *const T,
|
||
end: *const T,
|
||
}
|
||
|
||
#[stable(feature = "vec_intoiter_debug", since = "1.13.0")]
|
||
impl<T: fmt::Debug> fmt::Debug for IntoIter<T> {
|
||
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
f.debug_tuple("IntoIter").field(&self.as_slice()).finish()
|
||
}
|
||
}
|
||
|
||
impl<T> IntoIter<T> {
|
||
/// Returns the remaining items of this iterator as a slice.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let vec = vec!['a', 'b', 'c'];
|
||
/// let mut into_iter = vec.into_iter();
|
||
/// assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']);
|
||
/// let _ = into_iter.next().unwrap();
|
||
/// assert_eq!(into_iter.as_slice(), &['b', 'c']);
|
||
/// ```
|
||
#[stable(feature = "vec_into_iter_as_slice", since = "1.15.0")]
|
||
pub fn as_slice(&self) -> &[T] {
|
||
unsafe { slice::from_raw_parts(self.ptr, self.len()) }
|
||
}
|
||
|
||
/// Returns the remaining items of this iterator as a mutable slice.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let vec = vec!['a', 'b', 'c'];
|
||
/// let mut into_iter = vec.into_iter();
|
||
/// assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']);
|
||
/// into_iter.as_mut_slice()[2] = 'z';
|
||
/// assert_eq!(into_iter.next().unwrap(), 'a');
|
||
/// assert_eq!(into_iter.next().unwrap(), 'b');
|
||
/// assert_eq!(into_iter.next().unwrap(), 'z');
|
||
/// ```
|
||
#[stable(feature = "vec_into_iter_as_slice", since = "1.15.0")]
|
||
pub fn as_mut_slice(&mut self) -> &mut [T] {
|
||
unsafe { slice::from_raw_parts_mut(self.ptr as *mut T, self.len()) }
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
unsafe impl<T: Send> Send for IntoIter<T> {}
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
unsafe impl<T: Sync> Sync for IntoIter<T> {}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T> Iterator for IntoIter<T> {
|
||
type Item = T;
|
||
|
||
#[inline]
|
||
fn next(&mut self) -> Option<T> {
|
||
unsafe {
|
||
if self.ptr as *const _ == self.end {
|
||
None
|
||
} else {
|
||
if mem::size_of::<T>() == 0 {
|
||
// purposefully don't use 'ptr.offset' because for
|
||
// vectors with 0-size elements this would return the
|
||
// same pointer.
|
||
self.ptr = arith_offset(self.ptr as *const i8, 1) as *mut T;
|
||
|
||
// Make up a value of this ZST.
|
||
Some(mem::zeroed())
|
||
} else {
|
||
let old = self.ptr;
|
||
self.ptr = self.ptr.offset(1);
|
||
|
||
Some(ptr::read(old))
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
#[inline]
|
||
fn size_hint(&self) -> (usize, Option<usize>) {
|
||
let exact = if mem::size_of::<T>() == 0 {
|
||
(self.end as usize).wrapping_sub(self.ptr as usize)
|
||
} else {
|
||
unsafe { self.end.offset_from(self.ptr) as usize }
|
||
};
|
||
(exact, Some(exact))
|
||
}
|
||
|
||
#[inline]
|
||
fn count(self) -> usize {
|
||
self.len()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T> DoubleEndedIterator for IntoIter<T> {
|
||
#[inline]
|
||
fn next_back(&mut self) -> Option<T> {
|
||
unsafe {
|
||
if self.end == self.ptr {
|
||
None
|
||
} else {
|
||
if mem::size_of::<T>() == 0 {
|
||
// See above for why 'ptr.offset' isn't used
|
||
self.end = arith_offset(self.end as *const i8, -1) as *mut T;
|
||
|
||
// Make up a value of this ZST.
|
||
Some(mem::zeroed())
|
||
} else {
|
||
self.end = self.end.offset(-1);
|
||
|
||
Some(ptr::read(self.end))
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T> ExactSizeIterator for IntoIter<T> {
|
||
fn is_empty(&self) -> bool {
|
||
self.ptr == self.end
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "fused", since = "1.26.0")]
|
||
impl<T> FusedIterator for IntoIter<T> {}
|
||
|
||
#[unstable(feature = "trusted_len", issue = "37572")]
|
||
unsafe impl<T> TrustedLen for IntoIter<T> {}
|
||
|
||
#[stable(feature = "vec_into_iter_clone", since = "1.8.0")]
|
||
impl<T: Clone> Clone for IntoIter<T> {
|
||
fn clone(&self) -> IntoIter<T> {
|
||
self.as_slice().to_owned().into_iter()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
unsafe impl<#[may_dangle] T> Drop for IntoIter<T> {
|
||
fn drop(&mut self) {
|
||
struct DropGuard<'a, T>(&'a mut IntoIter<T>);
|
||
|
||
impl<T> Drop for DropGuard<'_, T> {
|
||
fn drop(&mut self) {
|
||
// RawVec handles deallocation
|
||
let _ = unsafe { RawVec::from_raw_parts(self.0.buf.as_ptr(), self.0.cap) };
|
||
}
|
||
}
|
||
|
||
let guard = DropGuard(self);
|
||
// destroy the remaining elements
|
||
unsafe {
|
||
ptr::drop_in_place(guard.0.as_mut_slice());
|
||
}
|
||
// now `guard` will be dropped and do the rest
|
||
}
|
||
}
|
||
|
||
/// A draining iterator for `Vec<T>`.
|
||
///
|
||
/// This `struct` is created by the [`drain`] method on [`Vec`].
|
||
///
|
||
/// [`drain`]: struct.Vec.html#method.drain
|
||
/// [`Vec`]: struct.Vec.html
|
||
#[stable(feature = "drain", since = "1.6.0")]
|
||
pub struct Drain<'a, T: 'a> {
|
||
/// Index of tail to preserve
|
||
tail_start: usize,
|
||
/// Length of tail
|
||
tail_len: usize,
|
||
/// Current remaining range to remove
|
||
iter: slice::Iter<'a, T>,
|
||
vec: NonNull<Vec<T>>,
|
||
}
|
||
|
||
#[stable(feature = "collection_debug", since = "1.17.0")]
|
||
impl<T: fmt::Debug> fmt::Debug for Drain<'_, T> {
|
||
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
f.debug_tuple("Drain").field(&self.iter.as_slice()).finish()
|
||
}
|
||
}
|
||
|
||
impl<'a, T> Drain<'a, T> {
|
||
/// Returns the remaining items of this iterator as a slice.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// # #![feature(vec_drain_as_slice)]
|
||
/// let mut vec = vec!['a', 'b', 'c'];
|
||
/// let mut drain = vec.drain(..);
|
||
/// assert_eq!(drain.as_slice(), &['a', 'b', 'c']);
|
||
/// let _ = drain.next().unwrap();
|
||
/// assert_eq!(drain.as_slice(), &['b', 'c']);
|
||
/// ```
|
||
#[unstable(feature = "vec_drain_as_slice", reason = "recently added", issue = "58957")]
|
||
pub fn as_slice(&self) -> &[T] {
|
||
self.iter.as_slice()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "drain", since = "1.6.0")]
|
||
unsafe impl<T: Sync> Sync for Drain<'_, T> {}
|
||
#[stable(feature = "drain", since = "1.6.0")]
|
||
unsafe impl<T: Send> Send for Drain<'_, T> {}
|
||
|
||
#[stable(feature = "drain", since = "1.6.0")]
|
||
impl<T> Iterator for Drain<'_, T> {
|
||
type Item = T;
|
||
|
||
#[inline]
|
||
fn next(&mut self) -> Option<T> {
|
||
self.iter.next().map(|elt| unsafe { ptr::read(elt as *const _) })
|
||
}
|
||
|
||
fn size_hint(&self) -> (usize, Option<usize>) {
|
||
self.iter.size_hint()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "drain", since = "1.6.0")]
|
||
impl<T> DoubleEndedIterator for Drain<'_, T> {
|
||
#[inline]
|
||
fn next_back(&mut self) -> Option<T> {
|
||
self.iter.next_back().map(|elt| unsafe { ptr::read(elt as *const _) })
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "drain", since = "1.6.0")]
|
||
impl<T> Drop for Drain<'_, T> {
|
||
fn drop(&mut self) {
|
||
/// Continues dropping the remaining elements in the `Drain`, then moves back the
|
||
/// un-`Drain`ed elements to restore the original `Vec`.
|
||
struct DropGuard<'r, 'a, T>(&'r mut Drain<'a, T>);
|
||
|
||
impl<'r, 'a, T> Drop for DropGuard<'r, 'a, T> {
|
||
fn drop(&mut self) {
|
||
// Continue the same loop we have below. If the loop already finished, this does
|
||
// nothing.
|
||
self.0.for_each(drop);
|
||
|
||
if self.0.tail_len > 0 {
|
||
unsafe {
|
||
let source_vec = self.0.vec.as_mut();
|
||
// memmove back untouched tail, update to new length
|
||
let start = source_vec.len();
|
||
let tail = self.0.tail_start;
|
||
if tail != start {
|
||
let src = source_vec.as_ptr().add(tail);
|
||
let dst = source_vec.as_mut_ptr().add(start);
|
||
ptr::copy(src, dst, self.0.tail_len);
|
||
}
|
||
source_vec.set_len(start + self.0.tail_len);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
// exhaust self first
|
||
while let Some(item) = self.next() {
|
||
let guard = DropGuard(self);
|
||
drop(item);
|
||
mem::forget(guard);
|
||
}
|
||
|
||
// Drop a `DropGuard` to move back the non-drained tail of `self`.
|
||
DropGuard(self);
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "drain", since = "1.6.0")]
|
||
impl<T> ExactSizeIterator for Drain<'_, T> {
|
||
fn is_empty(&self) -> bool {
|
||
self.iter.is_empty()
|
||
}
|
||
}
|
||
|
||
#[unstable(feature = "trusted_len", issue = "37572")]
|
||
unsafe impl<T> TrustedLen for Drain<'_, T> {}
|
||
|
||
#[stable(feature = "fused", since = "1.26.0")]
|
||
impl<T> FusedIterator for Drain<'_, T> {}
|
||
|
||
/// A splicing iterator for `Vec`.
|
||
///
|
||
/// This struct is created by the [`splice()`] method on [`Vec`]. See its
|
||
/// documentation for more.
|
||
///
|
||
/// [`splice()`]: struct.Vec.html#method.splice
|
||
/// [`Vec`]: struct.Vec.html
|
||
#[derive(Debug)]
|
||
#[stable(feature = "vec_splice", since = "1.21.0")]
|
||
pub struct Splice<'a, I: Iterator + 'a> {
|
||
drain: Drain<'a, I::Item>,
|
||
replace_with: I,
|
||
}
|
||
|
||
#[stable(feature = "vec_splice", since = "1.21.0")]
|
||
impl<I: Iterator> Iterator for Splice<'_, I> {
|
||
type Item = I::Item;
|
||
|
||
fn next(&mut self) -> Option<Self::Item> {
|
||
self.drain.next()
|
||
}
|
||
|
||
fn size_hint(&self) -> (usize, Option<usize>) {
|
||
self.drain.size_hint()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "vec_splice", since = "1.21.0")]
|
||
impl<I: Iterator> DoubleEndedIterator for Splice<'_, I> {
|
||
fn next_back(&mut self) -> Option<Self::Item> {
|
||
self.drain.next_back()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "vec_splice", since = "1.21.0")]
|
||
impl<I: Iterator> ExactSizeIterator for Splice<'_, I> {}
|
||
|
||
#[stable(feature = "vec_splice", since = "1.21.0")]
|
||
impl<I: Iterator> Drop for Splice<'_, I> {
|
||
fn drop(&mut self) {
|
||
self.drain.by_ref().for_each(drop);
|
||
|
||
unsafe {
|
||
if self.drain.tail_len == 0 {
|
||
self.drain.vec.as_mut().extend(self.replace_with.by_ref());
|
||
return;
|
||
}
|
||
|
||
// First fill the range left by drain().
|
||
if !self.drain.fill(&mut self.replace_with) {
|
||
return;
|
||
}
|
||
|
||
// There may be more elements. Use the lower bound as an estimate.
|
||
// FIXME: Is the upper bound a better guess? Or something else?
|
||
let (lower_bound, _upper_bound) = self.replace_with.size_hint();
|
||
if lower_bound > 0 {
|
||
self.drain.move_tail(lower_bound);
|
||
if !self.drain.fill(&mut self.replace_with) {
|
||
return;
|
||
}
|
||
}
|
||
|
||
// Collect any remaining elements.
|
||
// This is a zero-length vector which does not allocate if `lower_bound` was exact.
|
||
let mut collected = self.replace_with.by_ref().collect::<Vec<I::Item>>().into_iter();
|
||
// Now we have an exact count.
|
||
if collected.len() > 0 {
|
||
self.drain.move_tail(collected.len());
|
||
let filled = self.drain.fill(&mut collected);
|
||
debug_assert!(filled);
|
||
debug_assert_eq!(collected.len(), 0);
|
||
}
|
||
}
|
||
// Let `Drain::drop` move the tail back if necessary and restore `vec.len`.
|
||
}
|
||
}
|
||
|
||
/// Private helper methods for `Splice::drop`
|
||
impl<T> Drain<'_, T> {
|
||
/// The range from `self.vec.len` to `self.tail_start` contains elements
|
||
/// that have been moved out.
|
||
/// Fill that range as much as possible with new elements from the `replace_with` iterator.
|
||
/// Returns `true` if we filled the entire range. (`replace_with.next()` didn’t return `None`.)
|
||
unsafe fn fill<I: Iterator<Item = T>>(&mut self, replace_with: &mut I) -> bool {
|
||
let vec = self.vec.as_mut();
|
||
let range_start = vec.len;
|
||
let range_end = self.tail_start;
|
||
let range_slice =
|
||
slice::from_raw_parts_mut(vec.as_mut_ptr().add(range_start), range_end - range_start);
|
||
|
||
for place in range_slice {
|
||
if let Some(new_item) = replace_with.next() {
|
||
ptr::write(place, new_item);
|
||
vec.len += 1;
|
||
} else {
|
||
return false;
|
||
}
|
||
}
|
||
true
|
||
}
|
||
|
||
/// Makes room for inserting more elements before the tail.
|
||
unsafe fn move_tail(&mut self, extra_capacity: usize) {
|
||
let vec = self.vec.as_mut();
|
||
let used_capacity = self.tail_start + self.tail_len;
|
||
vec.buf.reserve(used_capacity, extra_capacity);
|
||
|
||
let new_tail_start = self.tail_start + extra_capacity;
|
||
let src = vec.as_ptr().add(self.tail_start);
|
||
let dst = vec.as_mut_ptr().add(new_tail_start);
|
||
ptr::copy(src, dst, self.tail_len);
|
||
self.tail_start = new_tail_start;
|
||
}
|
||
}
|
||
|
||
/// An iterator produced by calling `drain_filter` on Vec.
|
||
#[unstable(feature = "drain_filter", reason = "recently added", issue = "43244")]
|
||
#[derive(Debug)]
|
||
pub struct DrainFilter<'a, T, F>
|
||
where
|
||
F: FnMut(&mut T) -> bool,
|
||
{
|
||
vec: &'a mut Vec<T>,
|
||
/// The index of the item that will be inspected by the next call to `next`.
|
||
idx: usize,
|
||
/// The number of items that have been drained (removed) thus far.
|
||
del: usize,
|
||
/// The original length of `vec` prior to draining.
|
||
old_len: usize,
|
||
/// The filter test predicate.
|
||
pred: F,
|
||
/// A flag that indicates a panic has occurred in the filter test prodicate.
|
||
/// This is used as a hint in the drop implementation to prevent consumption
|
||
/// of the remainder of the `DrainFilter`. Any unprocessed items will be
|
||
/// backshifted in the `vec`, but no further items will be dropped or
|
||
/// tested by the filter predicate.
|
||
panic_flag: bool,
|
||
}
|
||
|
||
#[unstable(feature = "drain_filter", reason = "recently added", issue = "43244")]
|
||
impl<T, F> Iterator for DrainFilter<'_, T, F>
|
||
where
|
||
F: FnMut(&mut T) -> bool,
|
||
{
|
||
type Item = T;
|
||
|
||
fn next(&mut self) -> Option<T> {
|
||
unsafe {
|
||
while self.idx < self.old_len {
|
||
let i = self.idx;
|
||
let v = slice::from_raw_parts_mut(self.vec.as_mut_ptr(), self.old_len);
|
||
self.panic_flag = true;
|
||
let drained = (self.pred)(&mut v[i]);
|
||
self.panic_flag = false;
|
||
// Update the index *after* the predicate is called. If the index
|
||
// is updated prior and the predicate panics, the element at this
|
||
// index would be leaked.
|
||
self.idx += 1;
|
||
if drained {
|
||
self.del += 1;
|
||
return Some(ptr::read(&v[i]));
|
||
} else if self.del > 0 {
|
||
let del = self.del;
|
||
let src: *const T = &v[i];
|
||
let dst: *mut T = &mut v[i - del];
|
||
ptr::copy_nonoverlapping(src, dst, 1);
|
||
}
|
||
}
|
||
None
|
||
}
|
||
}
|
||
|
||
fn size_hint(&self) -> (usize, Option<usize>) {
|
||
(0, Some(self.old_len - self.idx))
|
||
}
|
||
}
|
||
|
||
#[unstable(feature = "drain_filter", reason = "recently added", issue = "43244")]
|
||
impl<T, F> Drop for DrainFilter<'_, T, F>
|
||
where
|
||
F: FnMut(&mut T) -> bool,
|
||
{
|
||
fn drop(&mut self) {
|
||
struct BackshiftOnDrop<'a, 'b, T, F>
|
||
where
|
||
F: FnMut(&mut T) -> bool,
|
||
{
|
||
drain: &'b mut DrainFilter<'a, T, F>,
|
||
}
|
||
|
||
impl<'a, 'b, T, F> Drop for BackshiftOnDrop<'a, 'b, T, F>
|
||
where
|
||
F: FnMut(&mut T) -> bool,
|
||
{
|
||
fn drop(&mut self) {
|
||
unsafe {
|
||
if self.drain.idx < self.drain.old_len && self.drain.del > 0 {
|
||
// This is a pretty messed up state, and there isn't really an
|
||
// obviously right thing to do. We don't want to keep trying
|
||
// to execute `pred`, so we just backshift all the unprocessed
|
||
// elements and tell the vec that they still exist. The backshift
|
||
// is required to prevent a double-drop of the last successfully
|
||
// drained item prior to a panic in the predicate.
|
||
let ptr = self.drain.vec.as_mut_ptr();
|
||
let src = ptr.add(self.drain.idx);
|
||
let dst = src.sub(self.drain.del);
|
||
let tail_len = self.drain.old_len - self.drain.idx;
|
||
src.copy_to(dst, tail_len);
|
||
}
|
||
self.drain.vec.set_len(self.drain.old_len - self.drain.del);
|
||
}
|
||
}
|
||
}
|
||
|
||
let backshift = BackshiftOnDrop { drain: self };
|
||
|
||
// Attempt to consume any remaining elements if the filter predicate
|
||
// has not yet panicked. We'll backshift any remaining elements
|
||
// whether we've already panicked or if the consumption here panics.
|
||
if !backshift.drain.panic_flag {
|
||
backshift.drain.for_each(drop);
|
||
}
|
||
}
|
||
}
|