// option. This file may not be copied, modified, or distributed
// except according to those terms.
-//! A growable list type with heap-allocated contents, written `Vec<T>` but
-//! pronounced 'vector.'
+//! A contiguous growable array type with heap-allocated contents, written
+//! `Vec<T>` but pronounced 'vector.'
//!
-//! Vectors have `O(1)` indexing, push (to the end) and pop (from the end).
+//! Vectors have `O(1)` indexing, amortized `O(1)` push (to the end) and
+//! `O(1)` pop (from the end).
//!
//! # Examples
//!
-//! Explicitly creating a `Vec<T>` with `new()`:
+//! You can explicitly create a [`Vec<T>`] with [`new`]:
//!
//! ```
-//! let xs: Vec<i32> = Vec::new();
+//! let v: Vec<i32> = Vec::new();
//! ```
//!
-//! Using the `vec!` macro:
+//! ...or by using the [`vec!`] macro:
//!
//! ```
-//! let ys: Vec<i32> = vec![];
+//! let v: Vec<i32> = vec![];
//!
-//! let zs = vec![1i32, 2, 3, 4, 5];
+//! let v = vec![1, 2, 3, 4, 5];
+//!
+//! let v = vec![0; 10]; // ten zeroes
//! ```
//!
-//! Push:
+//! You can [`push`] values onto the end of a vector (which will grow the vector
+//! as needed):
//!
//! ```
-//! let mut xs = vec![1i32, 2];
+//! let mut v = vec![1, 2];
//!
-//! xs.push(3);
+//! v.push(3);
//! ```
//!
-//! And pop:
+//! Popping values works in much the same way:
+//!
+//! ```
+//! let mut v = vec![1, 2];
//!
+//! let two = v.pop();
//! ```
-//! let mut xs = vec![1i32, 2];
//!
-//! let two = xs.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::prelude::*;
-
use alloc::boxed::Box;
-use alloc::heap::{EMPTY, allocate, reallocate, deallocate};
-use core::cmp::max;
+use alloc::raw_vec::RawVec;
+use borrow::ToOwned;
+use borrow::Cow;
use core::cmp::Ordering;
use core::fmt;
use core::hash::{self, Hash};
-use core::intrinsics::assume;
-use core::iter::{repeat, FromIterator};
-use core::marker::PhantomData;
+use core::intrinsics::{arith_offset, assume};
+use core::iter::{FromIterator, FusedIterator, TrustedLen};
use core::mem;
-use core::ops::{Index, IndexMut, Deref, Add};
+#[cfg(not(test))]
+use core::num::Float;
+use core::ops::{InPlace, Index, IndexMut, Place, Placer};
use core::ops;
use core::ptr;
-use core::ptr::Unique;
+use core::ptr::Shared;
use core::slice;
-use core::isize;
-use core::usize;
-
-use borrow::{Cow, IntoCow};
-// FIXME- fix places which assume the max vector allowed has memory usize::MAX.
-static MAX_MEMORY_SIZE: usize = isize::MAX as usize;
+use super::range::RangeArgument;
+use Bound::{Excluded, Included, Unbounded};
-/// A growable list type, written `Vec<T>` but pronounced 'vector.'
+/// A contiguous growable array type, written `Vec<T>` but pronounced 'vector'.
///
/// # Examples
///
/// ```
-/// # #![feature(collections)]
/// let mut vec = Vec::new();
/// vec.push(1);
/// vec.push(2);
/// vec[0] = 7;
/// assert_eq!(vec[0], 7);
///
-/// vec.push_all(&[1, 2, 3]);
+/// vec.extend([1, 2, 3].iter().cloned());
///
-/// for x in vec.iter() {
+/// for x in &vec {
/// println!("{}", x);
/// }
/// assert_eq!(vec, [7, 1, 2, 3]);
/// ```
///
-/// The `vec!` macro is provided to make initialization more convenient:
+/// The [`vec!`] macro is provided to make initialization more convenient:
///
/// ```
/// let mut vec = vec![1, 2, 3];
/// assert_eq!(vec, [1, 2, 3, 4]);
/// ```
///
+/// It can also initialize each element of a `Vec<T>` with a given value:
+///
+/// ```
+/// let vec = vec![0; 5];
+/// assert_eq!(vec, [0, 0, 0, 0, 0]);
+/// ```
+///
/// Use a `Vec<T>` as an efficient stack:
///
/// ```
/// stack.push(2);
/// stack.push(3);
///
-/// loop {
-/// let top = match stack.pop() {
-/// None => break, // empty
-/// Some(x) => x,
-/// };
+/// 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:
+///
+/// ```ignore
+/// let v = vec![0, 2, 4, 6];
+/// println!("{}", v[6]); // it will panic!
+/// ```
+///
+/// In conclusion: always check if the index you want to get really exists
+/// before doing it.
+///
+/// # 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 a 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
/// 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`
+/// 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.
-#[unsafe_no_drop_flag]
+///
+/// # 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 subtle enough that it is strongly recommended that you only
+/// free memory allocated by a `Vec` by creating a new `Vec` and 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 elements in order (what you would see
+/// if you coerced it to a slice), followed by [`capacity`]` - `[`len`]
+/// logically uninitialized 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`][`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
+/// [`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")]
pub struct Vec<T> {
- ptr: Unique<T>,
+ buf: RawVec<T>,
len: usize,
- cap: usize,
}
-unsafe impl<T: Send> Send for Vec<T> { }
-unsafe impl<T: Sync> Sync for Vec<T> { }
-
////////////////////////////////////////////////////////////////////////////////
// Inherent methods
////////////////////////////////////////////////////////////////////////////////
/// # Examples
///
/// ```
+ /// # #![allow(unused_mut)]
/// let mut vec: Vec<i32> = Vec::new();
/// ```
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub fn new() -> Vec<T> {
- // We want ptr to never be NULL so instead we set it to some arbitrary
- // non-null value which is fine since we never call deallocate on the ptr
- // if cap is 0. The reason for this is because the pointer of a slice
- // being NULL would break the null pointer optimization for enums.
- unsafe { Vec::from_raw_parts(EMPTY as *mut T, 0, 0) }
+ 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.
+ /// 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 this function does not specify the *length*
+ /// of the returned vector, but only the *capacity*. For an explanation of
+ /// the difference between length and capacity, see *[Capacity and reallocation]*.
///
- /// It is important to note that this function does not specify the *length* of the returned
- /// vector, but only the *capacity*. (For an explanation of the difference between length and
- /// capacity, see the main `Vec<T>` docs above, 'Capacity and reallocation'.)
+ /// [Capacity and reallocation]: #capacity-and-reallocation
///
/// # Examples
///
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub fn with_capacity(capacity: usize) -> Vec<T> {
- if mem::size_of::<T>() == 0 {
- unsafe { Vec::from_raw_parts(EMPTY as *mut T, 0, usize::MAX) }
- } else if capacity == 0 {
- Vec::new()
- } else {
- let size = capacity.checked_mul(mem::size_of::<T>())
- .expect("capacity overflow");
- let ptr = unsafe { allocate(size, mem::min_align_of::<T>()) };
- if ptr.is_null() { ::alloc::oom() }
- unsafe { Vec::from_raw_parts(ptr as *mut T, 0, capacity) }
+ Vec {
+ buf: RawVec::with_capacity(capacity),
+ len: 0,
}
}
/// Creates a `Vec<T>` directly from the raw components of another vector.
///
- /// This is highly unsafe, due to the number of invariants that aren't checked.
+ /// # 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).
+ /// * `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 datastructures. For example it is **not** safe
+ /// to build a `Vec<u8>` from a pointer to a C `char` array and a `size_t`.
+ ///
+ /// 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
///
/// # Examples
///
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
- pub unsafe fn from_raw_parts(ptr: *mut T, length: usize,
- capacity: usize) -> Vec<T> {
+ pub unsafe fn from_raw_parts(ptr: *mut T, length: usize, capacity: usize) -> Vec<T> {
Vec {
- ptr: Unique::new(ptr),
+ buf: RawVec::from_raw_parts(ptr, capacity),
len: length,
- cap: capacity,
}
}
- /// Creates a vector by copying the elements from a raw pointer.
- ///
- /// This function will copy `elts` contiguous elements starting at `ptr`
- /// into a new allocation owned by the returned `Vec<T>`. The elements of
- /// the buffer are copied into the vector without cloning, as if
- /// `ptr::read()` were called on them.
- #[inline]
- #[unstable(feature = "collections",
- reason = "may be better expressed via composition")]
- pub unsafe fn from_raw_buf(ptr: *const T, elts: usize) -> Vec<T> {
- let mut dst = Vec::with_capacity(elts);
- dst.set_len(elts);
- ptr::copy_nonoverlapping(ptr, dst.as_mut_ptr(), elts);
- dst
- }
-
/// Returns the number of elements the vector can hold without
/// reallocating.
///
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub fn capacity(&self) -> usize {
- self.cap
+ self.buf.cap()
}
/// 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.
+ /// frequent reallocations. After calling `reserve`, capacity will be
+ /// greater than or equal to `self.len() + additional`. Does nothing if
+ /// capacity is already sufficient.
///
/// # Panics
///
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn reserve(&mut self, additional: usize) {
- if self.cap - self.len < additional {
- const ERR_MSG: &'static str = "Vec::reserve: `isize` overflow";
-
- let new_min_cap = self.len.checked_add(additional).expect(ERR_MSG);
- if new_min_cap > MAX_MEMORY_SIZE { panic!(ERR_MSG) }
- self.grow_capacity(match new_min_cap.checked_next_power_of_two() {
- Some(x) if x > MAX_MEMORY_SIZE => MAX_MEMORY_SIZE,
- None => MAX_MEMORY_SIZE,
- Some(x) => x,
- });
- }
+ self.buf.reserve(self.len, additional);
}
/// Reserves the minimum capacity for exactly `additional` more elements to
- /// be inserted in the given `Vec<T>`. Does nothing if the capacity is already
- /// sufficient.
+ /// 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
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn reserve_exact(&mut self, additional: usize) {
- if self.cap - self.len < additional {
- match self.len.checked_add(additional) {
- None => panic!("Vec::reserve: `usize` overflow"),
- Some(new_cap) => self.grow_capacity(new_cap)
- }
- }
+ self.buf.reserve_exact(self.len, additional);
}
/// Shrinks the capacity of the vector as much as possible.
/// # Examples
///
/// ```
- /// # #![feature(collections)]
/// let mut vec = Vec::with_capacity(10);
- /// vec.push_all(&[1, 2, 3]);
+ /// 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 mem::size_of::<T>() == 0 { return }
-
- if self.len == 0 {
- if self.cap != 0 {
- unsafe {
- dealloc(*self.ptr, self.cap)
- }
- self.cap = 0;
- }
- } else if self.cap != self.len {
- unsafe {
- // Overflow check is unnecessary as the vector is already at
- // least this large.
- let ptr = reallocate(*self.ptr as *mut u8,
- self.cap * mem::size_of::<T>(),
- self.len * mem::size_of::<T>(),
- mem::min_align_of::<T>()) as *mut T;
- if ptr.is_null() { ::alloc::oom() }
- self.ptr = Unique::new(ptr);
- }
- self.cap = self.len;
- }
+ self.buf.shrink_to_fit(self.len);
}
- /// Converts the vector into Box<[T]>.
+ /// Converts the vector into [`Box<[T]>`][owned slice].
///
/// Note that this will drop any excess capacity. Calling this and
- /// converting back to a vector with `into_vec()` is equivalent to calling
- /// `shrink_to_fit()`.
+ /// converting back to a vector with [`into_vec`] is equivalent to calling
+ /// [`shrink_to_fit`].
+ ///
+ /// [owned slice]: ../../std/boxed/struct.Box.html
+ /// [`into_vec`]: ../../std/primitive.slice.html#method.into_vec
+ /// [`shrink_to_fit`]: #method.shrink_to_fit
+ ///
+ /// # 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]> {
- self.shrink_to_fit();
unsafe {
- let xs: Box<[T]> = Box::from_raw(&mut *self);
+ self.shrink_to_fit();
+ let buf = ptr::read(&self.buf);
mem::forget(self);
- xs
+ buf.into_box()
}
}
- /// Shorten a vector, dropping excess elements.
+ /// 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:
+ ///
/// ```
- /// # #![feature(collections)]
- /// let mut vec = vec![1, 2, 3, 4];
+ /// 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) {
unsafe {
// drop any extra elements
while len < self.len {
- // decrement len before the read(), so a panic on Drop doesn't
- // re-drop the just-failed value.
+ // decrement len before the drop_in_place(), so a panic on Drop
+ // doesn't re-drop the just-failed value.
self.len -= 1;
- ptr::read(self.get_unchecked(self.len));
+ let len = self.len;
+ ptr::drop_in_place(self.get_unchecked_mut(len));
}
}
}
/// 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]
- #[unstable(feature = "convert",
- reason = "waiting on RFC revision")]
+ #[stable(feature = "vec_as_slice", since = "1.7.0")]
pub fn as_slice(&self) -> &[T] {
self
}
- /// Deprecated: use `&mut s[..]` instead.
+ /// 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]
- #[unstable(feature = "convert",
- reason = "waiting on RFC revision")]
+ #[stable(feature = "vec_as_slice", since = "1.7.0")]
pub fn as_mut_slice(&mut self) -> &mut [T] {
- &mut self[..]
+ self
}
/// Sets the length of a vector.
/// # Examples
///
/// ```
- /// let mut v = vec![1, 2, 3, 4];
+ /// use std::ptr;
+ ///
+ /// let mut vec = vec!['r', 'u', 's', 't'];
+ ///
+ /// unsafe {
+ /// ptr::drop_in_place(&mut vec[3]);
+ /// vec.set_len(3);
+ /// }
+ /// assert_eq!(vec, ['r', 'u', 's']);
+ /// ```
+ ///
+ /// In this example, there is a memory leak since the memory locations
+ /// owned by 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]];
+ /// unsafe {
+ /// vec.set_len(0);
+ /// }
+ /// ```
+ ///
+ /// In this example, the vector gets expanded from zero to four items
+ /// without any memory allocations occurring, resulting in vector
+ /// values of unallocated memory:
+ ///
+ /// ```
+ /// let mut vec: Vec<char> = Vec::new();
+ ///
/// unsafe {
- /// v.set_len(1);
+ /// vec.set_len(4);
/// }
/// ```
#[inline]
self.len = len;
}
- /// Removes an element from anywhere in the vector and return it, replacing
- /// it with the last element.
+ /// 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).
///
}
/// Inserts an element at position `index` within the vector, shifting all
- /// elements after position `i` one position to the right.
+ /// elements after it to the right.
///
/// # Panics
///
- /// Panics if `index` is greater than the vector's length.
+ /// Panics if `index` is out of bounds.
///
/// # Examples
///
pub fn insert(&mut self, index: usize, element: T) {
let len = self.len();
assert!(index <= len);
+
// space for the new element
- self.reserve(1);
+ if len == self.buf.cap() {
+ self.buf.double();
+ }
- unsafe { // infallible
+ unsafe {
+ // infallible
// The spot to put the new value
{
let p = self.as_mut_ptr().offset(index as isize);
// Shift everything over to make space. (Duplicating the
// `index`th element into two consecutive places.)
- ptr::copy(&*p, p.offset(1), len - index);
+ ptr::copy(p, p.offset(1), len - index);
// Write it in, overwriting the first copy of the `index`th
// element.
- ptr::write(&mut *p, 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 position `index` one position to the left.
+ /// shifting all elements after it to the left.
///
/// # Panics
///
- /// Panics if `i` is out of bounds.
+ /// Panics if `index` is out of bounds.
///
/// # Examples
///
/// ```
- /// # #![feature(collections)]
/// let mut v = vec![1, 2, 3];
/// assert_eq!(v.remove(1), 2);
/// assert_eq!(v, [1, 3]);
pub fn remove(&mut self, index: usize) -> T {
let len = self.len();
assert!(index < len);
- unsafe { // infallible
+ unsafe {
+ // infallible
let ret;
{
// the place we are taking from.
ret = ptr::read(ptr);
// Shift everything down to fill in that spot.
- ptr::copy(&*ptr.offset(1), ptr, len - index - 1);
+ 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.
+ /// In other words, remove all elements `e` such that `f(&e)` returns `false`.
/// This method operates in place and preserves the order of the retained
/// elements.
///
/// assert_eq!(vec, [2, 4]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
- pub fn retain<F>(&mut self, mut f: F) where F: FnMut(&T) -> bool {
+ pub fn retain<F>(&mut self, mut f: F)
+ where F: FnMut(&T) -> bool
+ {
let len = self.len();
let mut del = 0;
{
if !f(&v[i]) {
del += 1;
} else if del > 0 {
- v.swap(i-del, i);
+ v.swap(i - del, i);
}
}
}
}
}
+ /// Removes 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 consecutive elements in the vector according to a predicate.
+ ///
+ /// The `same_bucket` function is passed references to two elements from the vector, and
+ /// returns `true` if the elements compare equal, or `false` if they do not. Only the first
+ /// of adjacent equal items is kept.
+ ///
+ /// If the vector is sorted, this removes all duplicates.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use std::ascii::AsciiExt;
+ ///
+ /// 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, mut same_bucket: F) where F: FnMut(&mut T, &mut T) -> bool {
+ unsafe {
+ // Although we have a mutable reference to `self`, we cannot make
+ // *arbitrary* changes. The `same_bucket` calls could panic, so we
+ // must ensure that the vector is in a valid state at all time.
+ //
+ // The way that we handle this is by using swaps; we iterate
+ // over all the elements, swapping as we go so that at the end
+ // the elements we wish to keep are in the front, and those we
+ // wish to reject are at the back. We can then truncate the
+ // vector. This operation is still O(n).
+ //
+ // Example: We start in this state, where `r` represents "next
+ // read" and `w` represents "next_write`.
+ //
+ // r
+ // +---+---+---+---+---+---+
+ // | 0 | 1 | 1 | 2 | 3 | 3 |
+ // +---+---+---+---+---+---+
+ // w
+ //
+ // Comparing self[r] against self[w-1], this is not a duplicate, so
+ // we swap self[r] and self[w] (no effect as r==w) and then increment both
+ // r and w, leaving us with:
+ //
+ // r
+ // +---+---+---+---+---+---+
+ // | 0 | 1 | 1 | 2 | 3 | 3 |
+ // +---+---+---+---+---+---+
+ // w
+ //
+ // Comparing self[r] against self[w-1], this value is a duplicate,
+ // so we increment `r` but leave everything else unchanged:
+ //
+ // r
+ // +---+---+---+---+---+---+
+ // | 0 | 1 | 1 | 2 | 3 | 3 |
+ // +---+---+---+---+---+---+
+ // w
+ //
+ // Comparing self[r] against self[w-1], this is not a duplicate,
+ // so swap self[r] and self[w] and advance r and w:
+ //
+ // r
+ // +---+---+---+---+---+---+
+ // | 0 | 1 | 2 | 1 | 3 | 3 |
+ // +---+---+---+---+---+---+
+ // w
+ //
+ // Not a duplicate, repeat:
+ //
+ // r
+ // +---+---+---+---+---+---+
+ // | 0 | 1 | 2 | 3 | 1 | 3 |
+ // +---+---+---+---+---+---+
+ // w
+ //
+ // Duplicate, advance r. End of vec. Truncate to w.
+
+ let ln = self.len();
+ if ln <= 1 {
+ return;
+ }
+
+ // Avoid bounds checks by using raw pointers.
+ let p = self.as_mut_ptr();
+ let mut r: usize = 1;
+ let mut w: usize = 1;
+
+ while r < ln {
+ let p_r = p.offset(r as isize);
+ let p_wm1 = p.offset((w - 1) as isize);
+ if !same_bucket(&mut *p_r, &mut *p_wm1) {
+ if r != w {
+ let p_w = p_wm1.offset(1);
+ mem::swap(&mut *p_r, &mut *p_w);
+ }
+ w += 1;
+ }
+ r += 1;
+ }
+
+ self.truncate(w);
+ }
+ }
+
/// Appends an element to the back of a collection.
///
/// # Panics
/// # Examples
///
/// ```
- /// let mut vec = vec!(1, 2);
+ /// 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) {
- #[cold]
- #[inline(never)]
- fn resize<T>(vec: &mut Vec<T>) {
- let old_size = vec.cap * mem::size_of::<T>();
- if old_size >= MAX_MEMORY_SIZE { panic!("capacity overflow") }
- let mut size = max(old_size, 2 * mem::size_of::<T>()) * 2;
- if old_size > size || size > MAX_MEMORY_SIZE {
- size = MAX_MEMORY_SIZE;
- }
- unsafe {
- let ptr = alloc_or_realloc(*vec.ptr, old_size, size);
- if ptr.is_null() { ::alloc::oom() }
- vec.ptr = Unique::new(ptr);
- }
- vec.cap = max(vec.cap, 2) * 2;
- }
-
- if mem::size_of::<T>() == 0 {
- // zero-size types consume no memory, so we can't rely on the
- // address space running out
- self.len = self.len.checked_add(1).expect("length overflow");
- unsafe { mem::forget(value); }
- return
- }
-
- if self.len == self.cap {
- resize(self);
+ // 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.cap() {
+ self.buf.double();
}
-
unsafe {
- let end = (*self.ptr).offset(self.len as isize);
- ptr::write(&mut *end, value);
+ let end = self.as_mut_ptr().offset(self.len as isize);
+ ptr::write(end, value);
self.len += 1;
}
}
- /// Removes the last element from a vector and returns it, or `None` if it is empty.
+ /// Returns a place for insertion at the back of the `Vec`.
+ ///
+ /// Using this method with placement syntax is equivalent to [`push`](#method.push),
+ /// but may be more efficient.
///
/// # Examples
///
/// ```
- /// let mut vec = vec![1, 2, 3];
- /// assert_eq!(vec.pop(), Some(3));
- /// assert_eq!(vec, [1, 2]);
+ /// #![feature(collection_placement)]
+ /// #![feature(placement_in_syntax)]
+ ///
+ /// let mut vec = vec![1, 2];
+ /// vec.place_back() <- 3;
+ /// vec.place_back() <- 4;
+ /// assert_eq!(&vec, &[1, 2, 3, 4]);
/// ```
- #[inline]
- #[stable(feature = "rust1", since = "1.0.0")]
+ #[unstable(feature = "collection_placement",
+ reason = "placement protocol is subject to change",
+ issue = "30172")]
+ pub fn place_back(&mut self) -> PlaceBack<T> {
+ PlaceBack { vec: self }
+ }
+
+ /// 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
/// # Examples
///
/// ```
- /// # #![feature(collections)]
/// let mut vec = vec![1, 2, 3];
/// let mut vec2 = vec![4, 5, 6];
/// vec.append(&mut vec2);
/// assert_eq!(vec2, []);
/// ```
#[inline]
- #[unstable(feature = "collections",
- reason = "new API, waiting for dust to settle")]
+ #[stable(feature = "append", since = "1.4.0")]
pub fn append(&mut self, other: &mut Self) {
- if mem::size_of::<T>() == 0 {
- // zero-size types consume no memory, so we can't rely on the
- // address space running out
- self.len = self.len.checked_add(other.len()).expect("length overflow");
- unsafe { other.set_len(0) }
- return;
- }
- self.reserve(other.len());
- let len = self.len();
unsafe {
- ptr::copy_nonoverlapping(
- other.as_ptr(),
- self.get_unchecked_mut(len),
- other.len());
+ self.append_elements(other.as_slice() as _);
+ other.set_len(0);
}
+ }
- self.len += other.len();
- unsafe { 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.get_unchecked_mut(len), count);
+ self.len += count;
}
- /// Creates a draining iterator that clears the `Vec` and iterates over
- /// the removed items from start to end.
+ /// 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
///
/// ```
- /// # #![feature(collections)]
- /// let mut v = vec!["a".to_string(), "b".to_string()];
- /// for s in v.drain() {
- /// // s has type String, not &String
- /// println!("{}", s);
- /// }
- /// assert!(v.is_empty());
+ /// 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, &[]);
/// ```
- #[inline]
- #[unstable(feature = "collections",
- reason = "matches collection reform specification, waiting for dust to settle")]
- pub fn drain(&mut self) -> Drain<T> {
+ #[stable(feature = "drain", since = "1.6.0")]
+ pub fn drain<R>(&mut self, range: R) -> Drain<T>
+ where R: RangeArgument<usize>
+ {
+ // Memory safety
+ //
+ // When the Drain is first created, it shortens the length of
+ // the source vector to make sure no uninitalized 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() {
+ Included(&n) => n,
+ Excluded(&n) => n + 1,
+ Unbounded => 0,
+ };
+ let end = match range.end() {
+ Included(&n) => n + 1,
+ Excluded(&n) => n,
+ Unbounded => len,
+ };
+ assert!(start <= end);
+ assert!(end <= len);
+
unsafe {
- let begin = *self.ptr as *const T;
- let end = if mem::size_of::<T>() == 0 {
- (*self.ptr as usize + self.len()) as *const T
- } else {
- (*self.ptr).offset(self.len() as isize) as *const T
- };
- self.set_len(0);
+ // 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().offset(start as isize),
+ end - start);
Drain {
- ptr: begin,
- end: end,
- marker: PhantomData,
+ tail_start: end,
+ tail_len: len - end,
+ iter: range_slice.iter(),
+ vec: Shared::new(self as *mut _),
}
}
}
/// Clears the vector, removing all values.
///
+ /// Note that this method has no effect on the allocated capacity
+ /// of the vector.
+ ///
/// # Examples
///
/// ```
self.truncate(0)
}
- /// Returns the number of elements in the vector.
+ /// Returns the number of elements in the vector, also referred to
+ /// as its 'length'.
///
/// # Examples
///
/// ```
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
- pub fn len(&self) -> usize { self.len }
+ pub fn len(&self) -> usize {
+ self.len
+ }
/// Returns `true` if the vector contains no elements.
///
/// assert!(!v.is_empty());
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
- pub fn is_empty(&self) -> bool { self.len() == 0 }
-
- /// Converts a `Vec<T>` to a `Vec<U>` where `T` and `U` have the same
- /// size and in case they are not zero-sized the same minimal alignment.
- ///
- /// # Panics
- ///
- /// Panics if `T` and `U` have differing sizes or are not zero-sized and
- /// have differing minimal alignments.
- ///
- /// # Examples
- ///
- /// ```
- /// # #![feature(collections, core)]
- /// let v = vec![0, 1, 2];
- /// let w = v.map_in_place(|i| i + 3);
- /// assert_eq!(&w[..], &[3, 4, 5]);
- ///
- /// #[derive(PartialEq, Debug)]
- /// struct Newtype(u8);
- /// let bytes = vec![0x11, 0x22];
- /// let newtyped_bytes = bytes.map_in_place(|x| Newtype(x));
- /// assert_eq!(&newtyped_bytes[..], &[Newtype(0x11), Newtype(0x22)]);
- /// ```
- #[unstable(feature = "collections",
- reason = "API may change to provide stronger guarantees")]
- pub fn map_in_place<U, F>(self, mut f: F) -> Vec<U> where F: FnMut(T) -> U {
- // FIXME: Assert statically that the types `T` and `U` have the same
- // size.
- assert!(mem::size_of::<T>() == mem::size_of::<U>());
-
- let mut vec = self;
-
- if mem::size_of::<T>() != 0 {
- // FIXME: Assert statically that the types `T` and `U` have the
- // same minimal alignment in case they are not zero-sized.
-
- // These asserts are necessary because the `min_align_of` of the
- // types are passed to the allocator by `Vec`.
- assert!(mem::min_align_of::<T>() == mem::min_align_of::<U>());
-
- // This `as isize` cast is safe, because the size of the elements of the
- // vector is not 0, and:
- //
- // 1) If the size of the elements in the vector is 1, the `isize` may
- // overflow, but it has the correct bit pattern so that the
- // `.offset()` function will work.
- //
- // Example:
- // Address space 0x0-0xF.
- // `u8` array at: 0x1.
- // Size of `u8` array: 0x8.
- // Calculated `offset`: -0x8.
- // After `array.offset(offset)`: 0x9.
- // (0x1 + 0x8 = 0x1 - 0x8)
- //
- // 2) If the size of the elements in the vector is >1, the `usize` ->
- // `isize` conversion can't overflow.
- let offset = vec.len() as isize;
- let start = vec.as_mut_ptr();
-
- let mut pv = PartialVecNonZeroSized {
- vec: vec,
-
- start_t: start,
- // This points inside the vector, as the vector has length
- // `offset`.
- end_t: unsafe { start.offset(offset) },
- start_u: start as *mut U,
- end_u: start as *mut U,
-
- _marker: PhantomData,
- };
- // start_t
- // start_u
- // |
- // +-+-+-+-+-+-+
- // |T|T|T|...|T|
- // +-+-+-+-+-+-+
- // | |
- // end_u end_t
-
- while pv.end_u as *mut T != pv.end_t {
- unsafe {
- // start_u start_t
- // | |
- // +-+-+-+-+-+-+-+-+-+
- // |U|...|U|T|T|...|T|
- // +-+-+-+-+-+-+-+-+-+
- // | |
- // end_u end_t
-
- let t = ptr::read(pv.start_t);
- // start_u start_t
- // | |
- // +-+-+-+-+-+-+-+-+-+
- // |U|...|U|X|T|...|T|
- // +-+-+-+-+-+-+-+-+-+
- // | |
- // end_u end_t
- // We must not panic here, one cell is marked as `T`
- // although it is not `T`.
-
- pv.start_t = pv.start_t.offset(1);
- // start_u start_t
- // | |
- // +-+-+-+-+-+-+-+-+-+
- // |U|...|U|X|T|...|T|
- // +-+-+-+-+-+-+-+-+-+
- // | |
- // end_u end_t
- // We may panic again.
-
- // The function given by the user might panic.
- let u = f(t);
-
- ptr::write(pv.end_u, u);
- // start_u start_t
- // | |
- // +-+-+-+-+-+-+-+-+-+
- // |U|...|U|U|T|...|T|
- // +-+-+-+-+-+-+-+-+-+
- // | |
- // end_u end_t
- // We should not panic here, because that would leak the `U`
- // pointed to by `end_u`.
-
- pv.end_u = pv.end_u.offset(1);
- // start_u start_t
- // | |
- // +-+-+-+-+-+-+-+-+-+
- // |U|...|U|U|T|...|T|
- // +-+-+-+-+-+-+-+-+-+
- // | |
- // end_u end_t
- // We may panic again.
- }
- }
-
- // start_u start_t
- // | |
- // +-+-+-+-+-+-+
- // |U|...|U|U|U|
- // +-+-+-+-+-+-+
- // |
- // end_t
- // end_u
- // Extract `vec` and prevent the destructor of
- // `PartialVecNonZeroSized` from running. Note that none of the
- // function calls can panic, thus no resources can be leaked (as the
- // `vec` member of `PartialVec` is the only one which holds
- // allocations -- and it is returned from this function. None of
- // this can panic.
- unsafe {
- let vec_len = pv.vec.len();
- let vec_cap = pv.vec.capacity();
- let vec_ptr = pv.vec.as_mut_ptr() as *mut U;
- mem::forget(pv);
- Vec::from_raw_parts(vec_ptr, vec_len, vec_cap)
- }
- } else {
- // Put the `Vec` into the `PartialVecZeroSized` structure and
- // prevent the destructor of the `Vec` from running. Since the
- // `Vec` contained zero-sized objects, it did not allocate, so we
- // are not leaking memory here.
- let mut pv = PartialVecZeroSized::<T,U> {
- num_t: vec.len(),
- num_u: 0,
- marker: PhantomData,
- };
- unsafe { mem::forget(vec); }
-
- while pv.num_t != 0 {
- unsafe {
- // Create a `T` out of thin air and decrement `num_t`. This
- // must not panic between these steps, as otherwise a
- // destructor of `T` which doesn't exist runs.
- let t = mem::uninitialized();
- pv.num_t -= 1;
-
- // The function given by the user might panic.
- let u = f(t);
-
- // Forget the `U` and increment `num_u`. This increment
- // cannot overflow the `usize` as we only do this for a
- // number of times that fits into a `usize` (and start with
- // `0`). Again, we should not panic between these steps.
- mem::forget(u);
- pv.num_u += 1;
- }
- }
- // Create a `Vec` from our `PartialVecZeroSized` and make sure the
- // destructor of the latter will not run. None of this can panic.
- let mut result = Vec::new();
- unsafe {
- result.set_len(pv.num_u);
- mem::forget(pv);
- }
- result
- }
+ pub fn is_empty(&self) -> bool {
+ self.len() == 0
}
/// Splits the collection into two at the given index.
/// # Examples
///
/// ```
- /// # #![feature(collections)]
/// let mut vec = vec![1,2,3];
/// let vec2 = vec.split_off(1);
/// assert_eq!(vec, [1]);
/// assert_eq!(vec2, [2, 3]);
/// ```
#[inline]
- #[unstable(feature = "collections",
- reason = "new API, waiting for dust to settle")]
+ #[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");
self.set_len(at);
other.set_len(other_len);
- ptr::copy_nonoverlapping(
- self.as_ptr().offset(at as isize),
- other.as_mut_ptr(),
- other.len());
+ ptr::copy_nonoverlapping(self.as_ptr().offset(at as isize),
+ other.as_mut_ptr(),
+ other.len());
}
other
}
-
}
impl<T: Clone> Vec<T> {
- /// Resizes the `Vec` in-place so that `len()` is equal to `new_len`.
+ /// 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.
///
- /// Calls either `extend()` or `truncate()` depending on whether `new_len`
- /// is larger than the current value of `len()` or not.
+ /// This method requires `Clone` to clone the passed value. If you'd
+ /// rather create a value with `Default` instead, see [`resize_default`].
///
/// # Examples
///
/// ```
- /// # #![feature(collections)]
/// let mut vec = vec!["hello"];
/// vec.resize(3, "world");
/// assert_eq!(vec, ["hello", "world", "world"]);
/// vec.resize(2, 0);
/// assert_eq!(vec, [1, 2]);
/// ```
- #[unstable(feature = "collections",
- reason = "matches collection reform specification; waiting for dust to settle")]
+ ///
+ /// [`resize_default`]: #method.resize_default
+ #[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(repeat(value).take(new_len - len));
+ self.extend_with(new_len - len, ExtendElement(value))
} else {
self.truncate(new_len);
}
}
- /// Appends all elements in a slice to the `Vec`.
+ /// 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
///
/// ```
- /// # #![feature(collections)]
/// let mut vec = vec![1];
- /// vec.push_all(&[2, 3, 4]);
+ /// vec.extend_from_slice(&[2, 3, 4]);
/// assert_eq!(vec, [1, 2, 3, 4]);
/// ```
- #[inline]
- #[unstable(feature = "collections",
- reason = "likely to be replaced by a more optimized extend")]
- pub fn push_all(&mut self, other: &[T]) {
- self.reserve(other.len());
+ #[stable(feature = "vec_extend_from_slice", since = "1.6.0")]
+ pub fn extend_from_slice(&mut self, other: &[T]) {
+ self.spec_extend(other.iter())
+ }
+}
- for i in 0..other.len() {
- let len = self.len();
+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
+ ///
+ /// ```
+ /// #![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
+ #[unstable(feature = "vec_resize_default", issue = "41758")]
+ pub fn resize_default(&mut self, new_len: usize) {
+ let len = self.len();
- // Unsafe code so this can be optimised to a memcpy (or something similarly
- // fast) when T is Copy. LLVM is easily confused, so any extra operations
- // during the loop can prevent this optimisation.
- unsafe {
- ptr::write(
- self.get_unchecked_mut(len),
- other.get_unchecked(i).clone());
- self.set_len(len + 1);
+ 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(&self) -> T;
+ fn last(self) -> T;
+}
+
+struct ExtendElement<T>(T);
+impl<T: Clone> ExtendWith<T> for ExtendElement<T> {
+ fn next(&self) -> T { self.0.clone() }
+ fn last(self) -> T { self.0 }
+}
+
+struct ExtendDefault;
+impl<T: Default> ExtendWith<T> for ExtendDefault {
+ fn next(&self) -> T { Default::default() }
+ fn last(self) -> T { Default::default() }
+}
+impl<T> Vec<T> {
+ /// Extend the vector by `n` values, using the given generator.
+ fn extend_with<E: ExtendWith<T>>(&mut self, n: usize, value: E) {
+ self.reserve(n);
+
+ unsafe {
+ let mut ptr = self.as_mut_ptr().offset(self.len() as isize);
+ // 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: len }
+ }
+
+ #[inline]
+ fn increment_len(&mut self, increment: usize) {
+ self.local_len += increment;
+ }
+}
+
+impl<'a> Drop for SetLenOnDrop<'a> {
+ #[inline]
+ fn drop(&mut self) {
+ *self.len = self.local_len;
+ }
+}
+
impl<T: PartialEq> Vec<T> {
/// Removes consecutive repeated elements in the vector.
///
/// assert_eq!(vec, [1, 2, 3, 2]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
+ #[inline]
pub fn dedup(&mut self) {
- unsafe {
- // Although we have a mutable reference to `self`, we cannot make
- // *arbitrary* changes. The `PartialEq` comparisons could panic, so we
- // must ensure that the vector is in a valid state at all time.
- //
- // The way that we handle this is by using swaps; we iterate
- // over all the elements, swapping as we go so that at the end
- // the elements we wish to keep are in the front, and those we
- // wish to reject are at the back. We can then truncate the
- // vector. This operation is still O(n).
- //
- // Example: We start in this state, where `r` represents "next
- // read" and `w` represents "next_write`.
- //
- // r
- // +---+---+---+---+---+---+
- // | 0 | 1 | 1 | 2 | 3 | 3 |
- // +---+---+---+---+---+---+
- // w
- //
- // Comparing self[r] against self[w-1], this is not a duplicate, so
- // we swap self[r] and self[w] (no effect as r==w) and then increment both
- // r and w, leaving us with:
- //
- // r
- // +---+---+---+---+---+---+
- // | 0 | 1 | 1 | 2 | 3 | 3 |
- // +---+---+---+---+---+---+
- // w
- //
- // Comparing self[r] against self[w-1], this value is a duplicate,
- // so we increment `r` but leave everything else unchanged:
- //
- // r
- // +---+---+---+---+---+---+
- // | 0 | 1 | 1 | 2 | 3 | 3 |
- // +---+---+---+---+---+---+
- // w
- //
- // Comparing self[r] against self[w-1], this is not a duplicate,
- // so swap self[r] and self[w] and advance r and w:
- //
- // r
- // +---+---+---+---+---+---+
- // | 0 | 1 | 2 | 1 | 3 | 3 |
- // +---+---+---+---+---+---+
- // w
- //
- // Not a duplicate, repeat:
- //
- // r
- // +---+---+---+---+---+---+
- // | 0 | 1 | 2 | 3 | 1 | 3 |
- // +---+---+---+---+---+---+
- // w
- //
- // Duplicate, advance r. End of vec. Truncate to w.
-
- let ln = self.len();
- if ln < 1 { return; }
-
- // Avoid bounds checks by using unsafe pointers.
- let p = self.as_mut_ptr();
- let mut r: usize = 1;
- let mut w: usize = 1;
-
- while r < ln {
- let p_r = p.offset(r as isize);
- let p_wm1 = p.offset((w - 1) as isize);
- if *p_r != *p_wm1 {
- if r != w {
- let p_w = p_wm1.offset(1);
- mem::swap(&mut *p_r, &mut *p_w);
- }
- w += 1;
- }
- r += 1;
- }
+ self.dedup_by(|a, b| a == b)
+ }
- self.truncate(w);
- }
+ /// 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(&mut self, item: &T) -> Option<T> {
+ let pos = match self.iter().position(|x| *x == *item) {
+ Some(x) => x,
+ None => return None,
+ };
+ Some(self.remove(pos))
}
}
// Internal methods and functions
////////////////////////////////////////////////////////////////////////////////
-impl<T> Vec<T> {
- /// Reserves capacity for exactly `capacity` elements in the given vector.
- ///
- /// If the capacity for `self` is already equal to or greater than the
- /// requested capacity, then no action is taken.
- fn grow_capacity(&mut self, capacity: usize) {
- if mem::size_of::<T>() == 0 { return }
-
- if capacity > self.cap {
- let size = capacity.checked_mul(mem::size_of::<T>())
- .expect("capacity overflow");
- unsafe {
- let ptr = alloc_or_realloc(*self.ptr, self.cap * mem::size_of::<T>(), size);
- if ptr.is_null() { ::alloc::oom() }
- self.ptr = Unique::new(ptr);
- }
- self.cap = capacity;
- }
- }
+#[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)
}
-// FIXME: #13996: need a way to mark the return value as `noalias`
-#[inline(never)]
-unsafe fn alloc_or_realloc<T>(ptr: *mut T, old_size: usize, size: usize) -> *mut T {
- if old_size == 0 {
- allocate(size, mem::min_align_of::<T>()) as *mut T
- } else {
- reallocate(ptr as *mut u8, old_size, size, mem::min_align_of::<T>()) as *mut T
- }
+// Specialization trait used for Vec::from_elem
+trait SpecFromElem: Sized {
+ fn from_elem(elem: Self, n: usize) -> Vec<Self>;
}
-#[inline]
-unsafe fn dealloc<T>(ptr: *mut T, len: usize) {
- if mem::size_of::<T>() != 0 {
- deallocate(ptr as *mut u8,
- len * mem::size_of::<T>(),
- mem::min_align_of::<T>())
+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
}
}
-#[doc(hidden)]
-#[stable(feature = "rust1", since = "1.0.0")]
-pub fn from_elem<T: Clone>(elem: T, n: usize) -> Vec<T> {
- unsafe {
- let mut v = Vec::with_capacity(n);
- let mut ptr = v.as_mut_ptr();
-
- // Write all elements except the last one
- for i in 1..n {
- ptr::write(ptr, Clone::clone(&elem));
- ptr = ptr.offset(1);
- v.set_len(i); // Increment the length in every step in case Clone::clone() panics
+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,
+ }
}
-
- if n > 0 {
- // We can write the last element directly without cloning needlessly
- ptr::write(ptr, elem);
+ unsafe {
+ let mut v = Vec::with_capacity(n);
+ ptr::write_bytes(v.as_mut_ptr(), elem, n);
v.set_len(n);
+ v
}
-
- v
}
}
+macro_rules! impl_spec_from_elem {
+ ($t: ty, $is_zero: expr) => {
+ impl SpecFromElem for $t {
+ #[inline]
+ fn from_elem(elem: $t, n: usize) -> Vec<$t> {
+ if $is_zero(elem) {
+ return Vec {
+ buf: RawVec::with_capacity_zeroed(n),
+ len: n,
+ }
+ }
+ let mut v = Vec::with_capacity(n);
+ v.extend_with(n, ExtendElement(elem));
+ v
+ }
+ }
+ };
+}
+
+impl_spec_from_elem!(i8, |x| x == 0);
+impl_spec_from_elem!(i16, |x| x == 0);
+impl_spec_from_elem!(i32, |x| x == 0);
+impl_spec_from_elem!(i64, |x| x == 0);
+impl_spec_from_elem!(i128, |x| x == 0);
+impl_spec_from_elem!(isize, |x| x == 0);
+
+impl_spec_from_elem!(u16, |x| x == 0);
+impl_spec_from_elem!(u32, |x| x == 0);
+impl_spec_from_elem!(u64, |x| x == 0);
+impl_spec_from_elem!(u128, |x| x == 0);
+impl_spec_from_elem!(usize, |x| x == 0);
+
+impl_spec_from_elem!(f32, |x: f32| x == 0. && x.is_sign_positive());
+impl_spec_from_elem!(f64, |x: f64| x == 0. && x.is_sign_positive());
+
////////////////////////////////////////////////////////////////////////////////
// Common trait implementations for Vec
////////////////////////////////////////////////////////////////////////////////
-#[unstable(feature = "collections")]
-impl<T:Clone> Clone for Vec<T> {
+#[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) }
+ 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
}
fn clone_from(&mut self, other: &Vec<T>) {
- // drop anything in self that will not be overwritten
- if self.len() > other.len() {
- self.truncate(other.len())
- }
-
- // reuse the contained values' allocations/resources.
- for (place, thing) in self.iter_mut().zip(other.iter()) {
- place.clone_from(thing)
- }
-
- // self.len <= other.len due to the truncate above, so the
- // slice here is always in-bounds.
- let slice = &other[self.len()..];
- self.push_all(slice);
+ other.as_slice().clone_into(self);
}
}
self
}
}
+#[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
+impl<T> ops::Index<ops::RangeInclusive<usize>> for Vec<T> {
+ type Output = [T];
+
+ #[inline]
+ fn index(&self, index: ops::RangeInclusive<usize>) -> &[T] {
+ Index::index(&**self, index)
+ }
+}
+#[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
+impl<T> ops::Index<ops::RangeToInclusive<usize>> for Vec<T> {
+ type Output = [T];
+
+ #[inline]
+ fn index(&self, index: ops::RangeToInclusive<usize>) -> &[T] {
+ Index::index(&**self, index)
+ }
+}
#[stable(feature = "rust1", since = "1.0.0")]
impl<T> ops::IndexMut<ops::Range<usize>> for Vec<T> {
-
#[inline]
fn index_mut(&mut self, index: ops::Range<usize>) -> &mut [T] {
IndexMut::index_mut(&mut **self, index)
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<T> ops::IndexMut<ops::RangeTo<usize>> for Vec<T> {
-
#[inline]
fn index_mut(&mut self, index: ops::RangeTo<usize>) -> &mut [T] {
IndexMut::index_mut(&mut **self, index)
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<T> ops::IndexMut<ops::RangeFrom<usize>> for Vec<T> {
-
#[inline]
fn index_mut(&mut self, index: ops::RangeFrom<usize>) -> &mut [T] {
IndexMut::index_mut(&mut **self, index)
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<T> ops::IndexMut<ops::RangeFull> for Vec<T> {
+ #[inline]
+ fn index_mut(&mut self, _index: ops::RangeFull) -> &mut [T] {
+ self
+ }
+}
+#[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
+impl<T> ops::IndexMut<ops::RangeInclusive<usize>> for Vec<T> {
+ #[inline]
+ fn index_mut(&mut self, index: ops::RangeInclusive<usize>) -> &mut [T] {
+ IndexMut::index_mut(&mut **self, index)
+ }
+}
+#[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
+impl<T> ops::IndexMut<ops::RangeToInclusive<usize>> for Vec<T> {
+ #[inline]
+ fn index_mut(&mut self, index: ops::RangeToInclusive<usize>) -> &mut [T] {
+ 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 {
+ let p = self.buf.ptr();
+ assume(!p.is_null());
+ slice::from_raw_parts(p, self.len)
+ }
+ }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> ops::DerefMut for Vec<T> {
+ fn deref_mut(&mut self) -> &mut [T] {
+ unsafe {
+ let ptr = self.buf.ptr();
+ assume(!ptr.is_null());
+ slice::from_raw_parts_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();
+ assume(!begin.is_null());
+ let end = if mem::size_of::<T>() == 0 {
+ arith_offset(begin as *const i8, self.len() as isize) as *const T
+ } else {
+ begin.offset(self.len() as isize) as *const T
+ };
+ let cap = self.buf.cap();
+ mem::forget(self);
+ IntoIter {
+ buf: Shared::new(begin),
+ cap: cap,
+ ptr: begin,
+ end: 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(mut 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().offset(self.len() as isize);
+ let mut local_len = SetLenOnDrop::new(&mut self.len);
+ for element in iterator {
+ 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
+ }
+ }
- #[inline]
- fn index_mut(&mut self, _index: ops::RangeFull) -> &mut [T] {
- self
+ fn spec_extend(&mut self, mut iterator: IntoIter<T>) {
+ unsafe {
+ self.append_elements(iterator.as_slice() as _);
+ }
+ iterator.ptr = iterator.end;
}
}
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T> ops::Deref for Vec<T> {
- type Target = [T];
+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())
+ }
- fn deref(&self) -> &[T] {
- unsafe {
- let p = *self.ptr;
- assume(p != 0 as *mut T);
- slice::from_raw_parts(p, self.len)
- }
+ default fn spec_extend(&mut self, iterator: I) {
+ self.spec_extend(iterator.cloned())
}
}
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T> ops::DerefMut for Vec<T> {
- fn deref_mut(&mut self) -> &mut [T] {
+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 ptr = *self.ptr;
- assume(!ptr.is_null());
- slice::from_raw_parts_mut(ptr, self.len)
+ let len = self.len();
+ self.set_len(len + slice.len());
+ self.get_unchecked_mut(len..).copy_from_slice(slice);
}
}
}
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T> FromIterator<T> for Vec<T> {
- #[inline]
- fn from_iter<I: IntoIterator<Item=T>>(iterable: I) -> Vec<T> {
- let mut iterator = iterable.into_iter();
- let (lower, _) = iterator.size_hint();
- let mut vector = Vec::with_capacity(lower);
-
+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 {
- // vector.push(item);
+ // self.push(item);
// }
- //
- // This equivalent crucially runs the iterator precisely once. Below we
- // actually in theory run the iterator twice (one without bounds checks
- // and one with). To achieve the "moral equivalent", we use the `if`
- // statement below to break out early.
- //
- // If the first loop has terminated, then we have one of two conditions.
- //
- // 1. The underlying iterator returned `None`. In this case we are
- // guaranteed that less than `vector.capacity()` elements have been
- // returned, so we break out early.
- // 2. The underlying iterator yielded `vector.capacity()` elements and
- // has not yielded `None` yet. In this case we run the iterator to
- // its end below.
- for element in iterator.by_ref().take(vector.capacity()) {
- let len = vector.len();
- unsafe {
- ptr::write(vector.get_unchecked_mut(len), element);
- vector.set_len(len + 1);
+ 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));
}
- }
-
- if vector.len() == vector.capacity() {
- for element in iterator {
- vector.push(element);
+ 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);
}
}
- vector
}
-}
-
-#[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.
+ /// 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`.
+ ///
+ /// Note 1: The element range is removed even if the iterator is not
+ /// consumed until the end.
+ ///
+ /// Note 2: It is unspecified how many elements are removed from the vector,
+ /// if the `Splice` value is leaked.
+ ///
+ /// Note 3: The input iterator `replace_with` is only consumed
+ /// when the `Splice` value is dropped.
+ ///
+ /// Note 4: 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 v = vec!["a".to_string(), "b".to_string()];
- /// for s in v.into_iter() {
- /// // s has type String, not &String
- /// println!("{}", s);
- /// }
+ /// #![feature(splice)]
+ /// 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]
- fn into_iter(self) -> IntoIter<T> {
- unsafe {
- let ptr = *self.ptr;
- assume(!ptr.is_null());
- let cap = self.cap;
- let begin = ptr as *const T;
- let end = if mem::size_of::<T>() == 0 {
- (ptr as usize + self.len()) as *const T
- } else {
- ptr.offset(self.len() as isize) as *const T
- };
- mem::forget(self);
- IntoIter { allocation: ptr, cap: cap, ptr: begin, end: end }
+ #[unstable(feature = "splice", reason = "recently added", issue = "32310")]
+ pub fn splice<R, I>(&mut self, range: R, replace_with: I) -> Splice<I::IntoIter>
+ where R: RangeArgument<usize>, I: IntoIterator<Item=T>
+ {
+ Splice {
+ drain: self.drain(range),
+ replace_with: replace_with.into_iter(),
}
}
-}
-
-#[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(mut self) -> slice::IterMut<'a, T> {
- self.iter_mut()
+#[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())
}
}
-#[unstable(feature = "collections", reason = "waiting on Extend stability")]
-impl<T> Extend<T> for Vec<T> {
- #[inline]
- fn extend<I: IntoIterator<Item=T>>(&mut self, iterable: I) {
- let iterator = iterable.into_iter();
- let (lower, _) = iterator.size_hint();
- self.reserve(lower);
- for element in iterator {
- self.push(element)
+macro_rules! __impl_slice_eq1 {
+ ($Lhs: ty, $Rhs: ty) => {
+ __impl_slice_eq1! { $Lhs, $Rhs, Sized }
+ };
+ ($Lhs: ty, $Rhs: ty, $Bound: ident) => {
+ #[stable(feature = "rust1", since = "1.0.0")]
+ impl<'a, 'b, A: $Bound, B> PartialEq<$Rhs> for $Lhs where A: PartialEq<B> {
+ #[inline]
+ fn eq(&self, other: &$Rhs) -> bool { self[..] == other[..] }
+ #[inline]
+ fn ne(&self, other: &$Rhs) -> bool { self[..] != other[..] }
}
}
}
30 31 32
}
+/// Implements comparison of vectors, lexicographically.
#[stable(feature = "rust1", since = "1.0.0")]
impl<T: PartialOrd> PartialOrd for Vec<T> {
#[inline]
#[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]
}
}
-#[unstable(feature = "collections",
- reason = "recent addition, needs more experience")]
-impl<'a, T: Clone> Add<&'a [T]> for Vec<T> {
- type Output = Vec<T>;
-
- #[inline]
- fn add(mut self, rhs: &[T]) -> Vec<T> {
- self.push_all(rhs);
- self
- }
-}
-
-#[unsafe_destructor]
#[stable(feature = "rust1", since = "1.0.0")]
-impl<T> Drop for Vec<T> {
+unsafe impl<#[may_dangle] T> Drop for Vec<T> {
fn drop(&mut self) {
- // This is (and should always remain) a no-op if the fields are
- // zeroed (when moving out, because of #[unsafe_no_drop_flag]).
- if self.cap != 0 && self.cap != mem::POST_DROP_USIZE {
- unsafe {
- for x in &*self {
- ptr::read(x);
- }
- dealloc(*self.ptr, self.cap)
- }
+ 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> {
- #[stable(feature = "rust1", since = "1.0.0")]
+ /// Creates an empty `Vec<T>`.
fn default() -> Vec<T> {
Vec::new()
}
}
}
+#[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] {
}
}
+#[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<'a, T: Clone> From<&'a [T]> for Vec<T> {
#[cfg(not(test))]
}
}
+#[stable(feature = "vec_from_mut", since = "1.19.0")]
+impl<'a, T: Clone> From<&'a mut [T]> for Vec<T> {
+ #[cfg(not(test))]
+ fn from(s: &'a mut [T]) -> Vec<T> {
+ s.to_vec()
+ }
+ #[cfg(test)]
+ fn from(s: &'a mut [T]) -> Vec<T> {
+ ::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()
+ }
+}
+
+#[stable(feature = "box_from_vec", since = "1.18.0")]
+impl<T> Into<Box<[T]>> for Vec<T> {
+ fn into(self) -> Box<[T]> {
+ self.into_boxed_slice()
+ }
+}
+
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a> From<&'a str> for Vec<u8> {
fn from(s: &'a str) -> Vec<u8> {
// Clone-on-write
////////////////////////////////////////////////////////////////////////////////
-#[unstable(feature = "collections")]
-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))
+#[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)
}
}
-impl<'a, T: 'a> IntoCow<'a, [T]> for Vec<T> where T: Clone {
- fn into_cow(self) -> Cow<'a, [T]> {
- Cow::Owned(self)
+#[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)
}
}
-impl<'a, T> IntoCow<'a, [T]> for &'a [T] where T: Clone {
- fn into_cow(self) -> Cow<'a, [T]> {
- Cow::Borrowed(self)
+#[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))
}
}
////////////////////////////////////////////////////////////////////////////////
/// An iterator that moves out of a vector.
+///
+/// This `struct` is created by the `into_iter` method on [`Vec`][`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> {
- allocation: *mut T, // the block of memory allocated for the vector
- cap: usize, // the capacity of the vector
+ buf: Shared<T>,
+ cap: usize,
ptr: *const T,
- end: *const T
+ end: *const T,
}
-unsafe impl<T: Send> Send for IntoIter<T> { }
-unsafe impl<T: Sync> Sync for IntoIter<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> {
- #[inline]
- /// Drops all items that have not yet been moved and returns the empty vector.
- #[unstable(feature = "collections")]
- pub fn into_inner(mut self) -> Vec<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 {
- for _x in self.by_ref() { }
- let IntoIter { allocation, cap, ptr: _ptr, end: _end } = self;
- mem::forget(self);
- Vec::from_raw_parts(allocation, 0, cap)
+ 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 == self.end {
+ 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 = mem::transmute(self.ptr as usize + 1);
+ self.ptr = arith_offset(self.ptr as *const i8, 1) as *mut T;
// Use a non-null pointer value
- Some(ptr::read(EMPTY as *mut T))
+ // (self.ptr might be null because of wrapping)
+ Some(ptr::read(1 as *mut T))
} else {
let old = self.ptr;
self.ptr = self.ptr.offset(1);
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
- let diff = (self.end as usize) - (self.ptr as usize);
- let size = mem::size_of::<T>();
- let exact = diff / (if size == 0 {1} else {size});
+ let exact = match self.ptr.offset_to(self.end) {
+ Some(x) => x as usize,
+ None => (self.end as usize).wrapping_sub(self.ptr as usize),
+ };
(exact, Some(exact))
}
+
+ #[inline]
+ fn count(self) -> usize {
+ self.len()
+ }
}
#[stable(feature = "rust1", since = "1.0.0")]
} else {
if mem::size_of::<T>() == 0 {
// See above for why 'ptr.offset' isn't used
- self.end = mem::transmute(self.end as usize - 1);
+ self.end = arith_offset(self.end as *const i8, -1) as *mut T;
// Use a non-null pointer value
- Some(ptr::read(EMPTY as *mut T))
+ // (self.end might be null because of wrapping)
+ Some(ptr::read(1 as *mut T))
} else {
self.end = self.end.offset(-1);
- Some(ptr::read(mem::transmute(self.end)))
+ Some(ptr::read(self.end))
}
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
-impl<T> ExactSizeIterator for IntoIter<T> {}
+impl<T> ExactSizeIterator for IntoIter<T> {
+ fn is_empty(&self) -> bool {
+ self.ptr == self.end
+ }
+}
+
+#[unstable(feature = "fused", issue = "35602")]
+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()
+ }
+}
-#[unsafe_destructor]
#[stable(feature = "rust1", since = "1.0.0")]
-impl<T> Drop for IntoIter<T> {
+unsafe impl<#[may_dangle] T> Drop for IntoIter<T> {
fn drop(&mut self) {
// destroy the remaining elements
- if self.cap != 0 {
- for _x in self.by_ref() {}
- unsafe {
- dealloc(self.allocation, self.cap);
- }
- }
+ for _x in self.by_ref() {}
+
+ // RawVec handles deallocation
+ let _ = unsafe { RawVec::from_raw_parts(self.buf.as_ptr(), self.cap) };
}
}
-/// An iterator that drains a vector.
-#[unsafe_no_drop_flag]
-#[unstable(feature = "collections",
- reason = "recently added as part of collections reform 2")]
-pub struct Drain<'a, T:'a> {
- ptr: *const T,
- end: *const T,
- marker: PhantomData<&'a T>,
+/// 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: Shared<Vec<T>>,
+}
+
+#[stable(feature = "collection_debug", since = "1.17.0")]
+impl<'a, T: 'a + fmt::Debug> fmt::Debug for Drain<'a, T> {
+ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+ f.debug_tuple("Drain")
+ .field(&self.iter.as_slice())
+ .finish()
+ }
}
+#[stable(feature = "drain", since = "1.6.0")]
unsafe impl<'a, T: Sync> Sync for Drain<'a, T> {}
+#[stable(feature = "drain", since = "1.6.0")]
unsafe impl<'a, T: Send> Send for Drain<'a, T> {}
-#[stable(feature = "rust1", since = "1.0.0")]
+#[stable(feature = "drain", since = "1.6.0")]
impl<'a, T> Iterator for Drain<'a, T> {
type Item = T;
#[inline]
fn next(&mut self) -> Option<T> {
- unsafe {
- if self.ptr == 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 = mem::transmute(self.ptr as usize + 1);
-
- // Use a non-null pointer value
- Some(ptr::read(EMPTY as *mut T))
- } else {
- let old = self.ptr;
- self.ptr = self.ptr.offset(1);
-
- Some(ptr::read(old))
- }
- }
- }
+ self.iter.next().map(|elt| unsafe { ptr::read(elt as *const _) })
}
- #[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
- let diff = (self.end as usize) - (self.ptr as usize);
- let size = mem::size_of::<T>();
- let exact = diff / (if size == 0 {1} else {size});
- (exact, Some(exact))
+ self.iter.size_hint()
}
}
-#[stable(feature = "rust1", since = "1.0.0")]
+#[stable(feature = "drain", since = "1.6.0")]
impl<'a, T> DoubleEndedIterator for Drain<'a, 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 = mem::transmute(self.end as usize - 1);
+ self.iter.next_back().map(|elt| unsafe { ptr::read(elt as *const _) })
+ }
+}
- // Use a non-null pointer value
- Some(ptr::read(EMPTY as *mut T))
- } else {
- self.end = self.end.offset(-1);
+#[stable(feature = "drain", since = "1.6.0")]
+impl<'a, T> Drop for Drain<'a, T> {
+ fn drop(&mut self) {
+ // exhaust self first
+ while let Some(_) = self.next() {}
- Some(ptr::read(self.end))
- }
+ if self.tail_len > 0 {
+ unsafe {
+ let source_vec = self.vec.as_mut();
+ // memmove back untouched tail, update to new length
+ let start = source_vec.len();
+ let tail = self.tail_start;
+ let src = source_vec.as_ptr().offset(tail as isize);
+ let dst = source_vec.as_mut_ptr().offset(start as isize);
+ ptr::copy(src, dst, self.tail_len);
+ source_vec.set_len(start + self.tail_len);
}
}
}
}
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, T> ExactSizeIterator for Drain<'a, T> {}
-
-#[unsafe_destructor]
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, T> Drop for Drain<'a, T> {
- fn drop(&mut self) {
- // self.ptr == self.end == mem::POST_DROP_USIZE if drop has already been called,
- // so we can use #[unsafe_no_drop_flag].
- // destroy the remaining elements
- for _x in self.by_ref() {}
+#[stable(feature = "drain", since = "1.6.0")]
+impl<'a, T> ExactSizeIterator for Drain<'a, T> {
+ fn is_empty(&self) -> bool {
+ self.iter.is_empty()
}
}
-////////////////////////////////////////////////////////////////////////////////
-// Conversion from &[T] to &Vec<T>
-////////////////////////////////////////////////////////////////////////////////
+#[unstable(feature = "fused", issue = "35602")]
+impl<'a, T> FusedIterator for Drain<'a, T> {}
-/// Wrapper type providing a `&Vec<T>` reference via `Deref`.
-#[unstable(feature = "collections")]
-pub struct DerefVec<'a, T:'a> {
- x: Vec<T>,
- l: PhantomData<&'a T>,
+/// A place for insertion at the back of a `Vec`.
+///
+/// See [`Vec::place_back`](struct.Vec.html#method.place_back) for details.
+#[must_use = "places do nothing unless written to with `<-` syntax"]
+#[unstable(feature = "collection_placement",
+ reason = "struct name and placement protocol are subject to change",
+ issue = "30172")]
+#[derive(Debug)]
+pub struct PlaceBack<'a, T: 'a> {
+ vec: &'a mut Vec<T>,
}
-#[unstable(feature = "collections")]
-impl<'a, T> Deref for DerefVec<'a, T> {
- type Target = Vec<T>;
-
- fn deref<'b>(&'b self) -> &'b Vec<T> {
- &self.x
+#[unstable(feature = "collection_placement",
+ reason = "placement protocol is subject to change",
+ issue = "30172")]
+impl<'a, T> Placer<T> for PlaceBack<'a, T> {
+ type Place = PlaceBack<'a, T>;
+
+ fn make_place(self) -> Self {
+ // 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.vec.len == self.vec.buf.cap() {
+ self.vec.buf.double();
+ }
+ self
}
}
-// Prevent the inner `Vec<T>` from attempting to deallocate memory.
-#[unsafe_destructor]
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, T> Drop for DerefVec<'a, T> {
- fn drop(&mut self) {
- self.x.len = 0;
- self.x.cap = 0;
+#[unstable(feature = "collection_placement",
+ reason = "placement protocol is subject to change",
+ issue = "30172")]
+impl<'a, T> Place<T> for PlaceBack<'a, T> {
+ fn pointer(&mut self) -> *mut T {
+ unsafe { self.vec.as_mut_ptr().offset(self.vec.len as isize) }
}
}
-/// Converts a slice to a wrapper type providing a `&Vec<T>` reference.
-#[unstable(feature = "collections")]
-pub fn as_vec<'a, T>(x: &'a [T]) -> DerefVec<'a, T> {
- unsafe {
- DerefVec {
- x: Vec::from_raw_parts(x.as_ptr() as *mut T, x.len(), x.len()),
- l: PhantomData,
- }
+#[unstable(feature = "collection_placement",
+ reason = "placement protocol is subject to change",
+ issue = "30172")]
+impl<'a, T> InPlace<T> for PlaceBack<'a, T> {
+ type Owner = &'a mut T;
+
+ unsafe fn finalize(mut self) -> &'a mut T {
+ let ptr = self.pointer();
+ self.vec.len += 1;
+ &mut *ptr
}
}
-////////////////////////////////////////////////////////////////////////////////
-// Partial vec, used for map_in_place
-////////////////////////////////////////////////////////////////////////////////
-/// An owned, partially type-converted vector of elements with non-zero size.
+/// A splicing iterator for `Vec`.
///
-/// `T` and `U` must have the same, non-zero size. They must also have the same
-/// alignment.
+/// This struct is created by the [`splice()`] method on [`Vec`]. See its
+/// documentation for more.
///
-/// When the destructor of this struct runs, all `U`s from `start_u` (incl.) to
-/// `end_u` (excl.) and all `T`s from `start_t` (incl.) to `end_t` (excl.) are
-/// destructed. Additionally the underlying storage of `vec` will be freed.
-struct PartialVecNonZeroSized<T,U> {
- vec: Vec<T>,
+/// [`splice()`]: struct.Vec.html#method.splice
+/// [`Vec`]: struct.Vec.html
+#[derive(Debug)]
+#[unstable(feature = "splice", reason = "recently added", issue = "32310")]
+pub struct Splice<'a, I: Iterator + 'a> {
+ drain: Drain<'a, I::Item>,
+ replace_with: I,
+}
+
+#[unstable(feature = "splice", reason = "recently added", issue = "32310")]
+impl<'a, I: Iterator> Iterator for Splice<'a, I> {
+ type Item = I::Item;
- start_u: *mut U,
- end_u: *mut U,
- start_t: *mut T,
- end_t: *mut T,
+ fn next(&mut self) -> Option<Self::Item> {
+ self.drain.next()
+ }
- _marker: PhantomData<U>,
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ self.drain.size_hint()
+ }
}
-/// An owned, partially type-converted vector of zero-sized elements.
-///
-/// When the destructor of this struct runs, all `num_t` `T`s and `num_u` `U`s
-/// are destructed.
-struct PartialVecZeroSized<T,U> {
- num_t: usize,
- num_u: usize,
- marker: PhantomData<::core::cell::Cell<(T,U)>>,
+#[unstable(feature = "splice", reason = "recently added", issue = "32310")]
+impl<'a, I: Iterator> DoubleEndedIterator for Splice<'a, I> {
+ fn next_back(&mut self) -> Option<Self::Item> {
+ self.drain.next_back()
+ }
}
-#[unsafe_destructor]
-impl<T,U> Drop for PartialVecNonZeroSized<T,U> {
+#[unstable(feature = "splice", reason = "recently added", issue = "32310")]
+impl<'a, I: Iterator> ExactSizeIterator for Splice<'a, I> {}
+
+
+#[unstable(feature = "splice", reason = "recently added", issue = "32310")]
+impl<'a, I: Iterator> Drop for Splice<'a, I> {
fn drop(&mut self) {
+ // exhaust drain first
+ while let Some(_) = self.drain.next() {}
+
+
unsafe {
- // `vec` hasn't been modified until now. As it has a length
- // currently, this would run destructors of `T`s which might not be
- // there. So at first, set `vec`s length to `0`. This must be done
- // at first to remain memory-safe as the destructors of `U` or `T`
- // might cause unwinding where `vec`s destructor would be executed.
- self.vec.set_len(0);
-
- // We have instances of `U`s and `T`s in `vec`. Destruct them.
- while self.start_u != self.end_u {
- let _ = ptr::read(self.start_u); // Run a `U` destructor.
- self.start_u = self.start_u.offset(1);
+ 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
+ }
}
- while self.start_t != self.end_t {
- let _ = ptr::read(self.start_t); // Run a `T` destructor.
- self.start_t = self.start_t.offset(1);
+
+ // 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);
}
- // After this destructor ran, the destructor of `vec` will run,
- // deallocating the underlying memory.
}
+ // Let `Drain::drop` move the tail back if necessary and restore `vec.len`.
}
}
-#[unsafe_destructor]
-impl<T,U> Drop for PartialVecZeroSized<T,U> {
- fn drop(&mut self) {
- unsafe {
- // Destruct the instances of `T` and `U` this struct owns.
- while self.num_t != 0 {
- let _: T = mem::uninitialized(); // Run a `T` destructor.
- self.num_t -= 1;
- }
- while self.num_u != 0 {
- let _: U = mem::uninitialized(); // Run a `U` destructor.
- self.num_u -= 1;
+/// Private helper methods for `Splice::drop`
+impl<'a, T> Drain<'a, 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.
+ /// Return whether 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().offset(range_start as isize),
+ 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
+ }
+
+ /// Make 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().offset(self.tail_start as isize);
+ let dst = vec.as_mut_ptr().offset(new_tail_start as isize);
+ ptr::copy(src, dst, self.tail_len);
+ self.tail_start = new_tail_start;
}
}
projects / rustc.git / blobdiff