2738 lines
85 KiB
Rust
2738 lines
85 KiB
Rust
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! A contiguous growable array type with heap-allocated contents, written
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//! `Vec<T>`.
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//!
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//! Vectors have `O(1)` indexing, amortized `O(1)` push (to the end) and
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//! `O(1)` pop (from the end).
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//!
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//! # Examples
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//!
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//! You can explicitly create a [`Vec<T>`] with [`new`]:
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//!
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//! ```
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//! let v: Vec<i32> = Vec::new();
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//! ```
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//!
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//! ...or by using the [`vec!`] macro:
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//!
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//! ```
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//! let v: Vec<i32> = vec![];
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//!
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//! let v = vec![1, 2, 3, 4, 5];
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//!
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//! let v = vec![0; 10]; // ten zeroes
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//! ```
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//!
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//! You can [`push`] values onto the end of a vector (which will grow the vector
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//! as needed):
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//!
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//! ```
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//! let mut v = vec![1, 2];
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//!
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//! v.push(3);
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//! ```
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//!
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//! Popping values works in much the same way:
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//!
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//! ```
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//! let mut v = vec![1, 2];
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//!
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//! let two = v.pop();
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//! ```
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//!
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//! Vectors also support indexing (through the [`Index`] and [`IndexMut`] traits):
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//!
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//! ```
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//! let mut v = vec![1, 2, 3];
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//! let three = v[2];
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//! v[1] = v[1] + 5;
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//! ```
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//!
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//! [`Vec<T>`]: ../../std/vec/struct.Vec.html
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//! [`new`]: ../../std/vec/struct.Vec.html#method.new
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//! [`push`]: ../../std/vec/struct.Vec.html#method.push
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//! [`Index`]: ../../std/ops/trait.Index.html
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//! [`IndexMut`]: ../../std/ops/trait.IndexMut.html
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//! [`vec!`]: ../../std/macro.vec.html
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#![stable(feature = "rust1", since = "1.0.0")]
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use core::cmp::{self, Ordering};
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use core::fmt;
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use core::hash::{self, Hash};
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use core::intrinsics::{arith_offset, assume};
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use core::iter::{FromIterator, FusedIterator, TrustedLen};
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use core::marker::PhantomData;
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use core::mem;
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use core::ops::Bound::{Excluded, Included, Unbounded};
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use core::ops::{Index, IndexMut, RangeBounds};
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use core::ops;
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use core::ptr;
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use core::ptr::NonNull;
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use core::slice;
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use alloc::CollectionAllocErr;
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use borrow::ToOwned;
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use borrow::Cow;
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use boxed::Box;
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use raw_vec::RawVec;
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/// A contiguous growable array type, written `Vec<T>` but pronounced 'vector'.
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///
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/// # Examples
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///
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/// ```
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/// let mut vec = Vec::new();
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/// vec.push(1);
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/// vec.push(2);
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///
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/// assert_eq!(vec.len(), 2);
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/// assert_eq!(vec[0], 1);
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///
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/// assert_eq!(vec.pop(), Some(2));
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/// assert_eq!(vec.len(), 1);
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///
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/// vec[0] = 7;
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/// assert_eq!(vec[0], 7);
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///
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/// vec.extend([1, 2, 3].iter().cloned());
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///
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/// for x in &vec {
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/// println!("{}", x);
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/// }
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/// assert_eq!(vec, [7, 1, 2, 3]);
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/// ```
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///
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/// The [`vec!`] macro is provided to make initialization more convenient:
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///
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/// ```
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/// let mut vec = vec![1, 2, 3];
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/// vec.push(4);
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/// assert_eq!(vec, [1, 2, 3, 4]);
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/// ```
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///
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/// It can also initialize each element of a `Vec<T>` with a given value:
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///
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/// ```
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/// let vec = vec![0; 5];
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/// assert_eq!(vec, [0, 0, 0, 0, 0]);
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/// ```
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///
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/// Use a `Vec<T>` as an efficient stack:
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///
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/// ```
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/// let mut stack = Vec::new();
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///
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/// stack.push(1);
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/// stack.push(2);
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/// stack.push(3);
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///
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/// while let Some(top) = stack.pop() {
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/// // Prints 3, 2, 1
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/// println!("{}", top);
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/// }
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/// ```
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///
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/// # Indexing
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///
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/// The `Vec` type allows to access values by index, because it implements the
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/// [`Index`] trait. An example will be more explicit:
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///
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/// ```
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/// let v = vec![0, 2, 4, 6];
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/// println!("{}", v[1]); // it will display '2'
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/// ```
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///
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/// However be careful: if you try to access an index which isn't in the `Vec`,
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/// your software will panic! You cannot do this:
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///
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/// ```should_panic
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/// let v = vec![0, 2, 4, 6];
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/// println!("{}", v[6]); // it will panic!
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/// ```
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///
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/// In conclusion: always check if the index you want to get really exists
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/// before doing it.
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///
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/// # Slicing
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///
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/// A `Vec` can be mutable. Slices, on the other hand, are read-only objects.
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/// To get a slice, use `&`. Example:
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///
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/// ```
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/// fn read_slice(slice: &[usize]) {
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/// // ...
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/// }
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///
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/// let v = vec![0, 1];
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/// read_slice(&v);
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///
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/// // ... and that's all!
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/// // you can also do it like this:
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/// let x : &[usize] = &v;
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/// ```
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///
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/// In Rust, it's more common to pass slices as arguments rather than vectors
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/// when you just want to provide a read access. The same goes for [`String`] and
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/// [`&str`].
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///
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/// # Capacity and reallocation
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///
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/// The capacity of a vector is the amount of space allocated for any future
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/// elements that will be added onto the vector. This is not to be confused with
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/// the *length* of a vector, which specifies the number of actual elements
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/// within the vector. If a vector's length exceeds its capacity, its capacity
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/// will automatically be increased, but its elements will have to be
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/// reallocated.
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///
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/// For example, a vector with capacity 10 and length 0 would be an empty vector
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/// with space for 10 more elements. Pushing 10 or fewer elements onto the
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/// vector will not change its capacity or cause reallocation to occur. However,
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/// if the vector's length is increased to 11, it will have to reallocate, which
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/// can be slow. For this reason, it is recommended to use [`Vec::with_capacity`]
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/// whenever possible to specify how big the vector is expected to get.
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///
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/// # Guarantees
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///
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/// Due to its incredibly fundamental nature, `Vec` makes a lot of guarantees
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/// about its design. This ensures that it's as low-overhead as possible in
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/// the general case, and can be correctly manipulated in primitive ways
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/// by unsafe code. Note that these guarantees refer to an unqualified `Vec<T>`.
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/// If additional type parameters are added (e.g. to support custom allocators),
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/// overriding their defaults may change the behavior.
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///
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/// Most fundamentally, `Vec` is and always will be a (pointer, capacity, length)
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/// triplet. No more, no less. The order of these fields is completely
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/// unspecified, and you should use the appropriate methods to modify these.
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/// The pointer will never be null, so this type is null-pointer-optimized.
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///
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/// However, the pointer may not actually point to allocated memory. In particular,
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/// if you construct a `Vec` with capacity 0 via [`Vec::new`], [`vec![]`][`vec!`],
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/// [`Vec::with_capacity(0)`][`Vec::with_capacity`], or by calling [`shrink_to_fit`]
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/// on an empty Vec, it will not allocate memory. Similarly, if you store zero-sized
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/// types inside a `Vec`, it will not allocate space for them. *Note that in this case
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/// the `Vec` may not report a [`capacity`] of 0*. `Vec` will allocate if and only
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/// if [`mem::size_of::<T>`]`() * capacity() > 0`. In general, `Vec`'s allocation
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/// details are very subtle — if you intend to allocate memory using a `Vec`
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/// and use it for something else (either to pass to unsafe code, or to build your
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/// own memory-backed collection), be sure to deallocate this memory by using
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/// `from_raw_parts` to recover the `Vec` and then dropping it.
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///
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/// If a `Vec` *has* allocated memory, then the memory it points to is on the heap
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/// (as defined by the allocator Rust is configured to use by default), and its
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/// pointer points to [`len`] initialized, contiguous elements in order (what
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/// you would see if you coerced it to a slice), followed by [`capacity`]` -
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/// `[`len`] logically uninitialized, contiguous elements.
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///
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/// `Vec` will never perform a "small optimization" where elements are actually
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/// stored on the stack for two reasons:
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///
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/// * It would make it more difficult for unsafe code to correctly manipulate
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/// a `Vec`. The contents of a `Vec` wouldn't have a stable address if it were
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/// only moved, and it would be more difficult to determine if a `Vec` had
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/// actually allocated memory.
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///
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/// * It would penalize the general case, incurring an additional branch
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/// on every access.
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///
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/// `Vec` will never automatically shrink itself, even if completely empty. This
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/// ensures no unnecessary allocations or deallocations occur. Emptying a `Vec`
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/// and then filling it back up to the same [`len`] should incur no calls to
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/// the allocator. If you wish to free up unused memory, use
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/// [`shrink_to_fit`][`shrink_to_fit`].
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///
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/// [`push`] and [`insert`] will never (re)allocate if the reported capacity is
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/// sufficient. [`push`] and [`insert`] *will* (re)allocate if
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/// [`len`]` == `[`capacity`]. That is, the reported capacity is completely
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/// accurate, and can be relied on. It can even be used to manually free the memory
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/// allocated by a `Vec` if desired. Bulk insertion methods *may* reallocate, even
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/// when not necessary.
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///
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/// `Vec` does not guarantee any particular growth strategy when reallocating
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/// when full, nor when [`reserve`] is called. The current strategy is basic
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/// and it may prove desirable to use a non-constant growth factor. Whatever
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/// strategy is used will of course guarantee `O(1)` amortized [`push`].
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///
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/// `vec![x; n]`, `vec![a, b, c, d]`, and
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/// [`Vec::with_capacity(n)`][`Vec::with_capacity`], will all produce a `Vec`
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/// with exactly the requested capacity. If [`len`]` == `[`capacity`],
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/// (as is the case for the [`vec!`] macro), then a `Vec<T>` can be converted to
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/// and from a [`Box<[T]>`][owned slice] without reallocating or moving the elements.
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///
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/// `Vec` will not specifically overwrite any data that is removed from it,
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/// but also won't specifically preserve it. Its uninitialized memory is
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/// scratch space that it may use however it wants. It will generally just do
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/// whatever is most efficient or otherwise easy to implement. Do not rely on
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/// removed data to be erased for security purposes. Even if you drop a `Vec`, its
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/// buffer may simply be reused by another `Vec`. Even if you zero a `Vec`'s memory
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/// first, that may not actually happen because the optimizer does not consider
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/// this a side-effect that must be preserved. There is one case which we will
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/// not break, however: using `unsafe` code to write to the excess capacity,
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/// and then increasing the length to match, is always valid.
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///
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/// `Vec` does not currently guarantee the order in which elements are dropped.
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/// The order has changed in the past and may change again.
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///
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/// [`vec!`]: ../../std/macro.vec.html
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/// [`Index`]: ../../std/ops/trait.Index.html
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/// [`String`]: ../../std/string/struct.String.html
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/// [`&str`]: ../../std/primitive.str.html
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/// [`Vec::with_capacity`]: ../../std/vec/struct.Vec.html#method.with_capacity
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/// [`Vec::new`]: ../../std/vec/struct.Vec.html#method.new
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/// [`shrink_to_fit`]: ../../std/vec/struct.Vec.html#method.shrink_to_fit
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/// [`capacity`]: ../../std/vec/struct.Vec.html#method.capacity
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/// [`mem::size_of::<T>`]: ../../std/mem/fn.size_of.html
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/// [`len`]: ../../std/vec/struct.Vec.html#method.len
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/// [`push`]: ../../std/vec/struct.Vec.html#method.push
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/// [`insert`]: ../../std/vec/struct.Vec.html#method.insert
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/// [`reserve`]: ../../std/vec/struct.Vec.html#method.reserve
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/// [owned slice]: ../../std/boxed/struct.Box.html
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#[stable(feature = "rust1", since = "1.0.0")]
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pub struct Vec<T> {
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buf: RawVec<T>,
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len: usize,
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}
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////////////////////////////////////////////////////////////////////////////////
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// Inherent methods
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////////////////////////////////////////////////////////////////////////////////
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impl<T> Vec<T> {
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/// Constructs a new, empty `Vec<T>`.
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///
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/// The vector will not allocate until elements are pushed onto it.
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///
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/// # Examples
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///
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/// ```
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/// # #![allow(unused_mut)]
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/// let mut vec: Vec<i32> = Vec::new();
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/// ```
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#[inline]
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#[stable(feature = "rust1", since = "1.0.0")]
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#[rustc_const_unstable(feature = "const_vec_new")]
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pub const fn new() -> Vec<T> {
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Vec {
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buf: RawVec::new(),
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len: 0,
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}
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}
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/// Constructs a new, empty `Vec<T>` with the specified capacity.
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///
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/// The vector will be able to hold exactly `capacity` elements without
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/// reallocating. If `capacity` is 0, the vector will not allocate.
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///
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/// It is important to note that although the returned vector has the
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/// *capacity* specified, the vector will have a zero *length*. For an
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/// explanation of the difference between length and capacity, see
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/// *[Capacity and reallocation]*.
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///
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/// [Capacity and reallocation]: #capacity-and-reallocation
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///
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/// # Examples
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///
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/// ```
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/// let mut vec = Vec::with_capacity(10);
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///
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/// // The vector contains no items, even though it has capacity for more
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/// assert_eq!(vec.len(), 0);
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///
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/// // These are all done without reallocating...
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/// for i in 0..10 {
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/// vec.push(i);
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/// }
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///
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/// // ...but this may make the vector reallocate
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/// vec.push(11);
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/// ```
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#[inline]
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn with_capacity(capacity: usize) -> Vec<T> {
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Vec {
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buf: RawVec::with_capacity(capacity),
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len: 0,
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}
|
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}
|
||
|
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/// Creates a `Vec<T>` directly from the raw components of another vector.
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///
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/// # Safety
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///
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/// This is highly unsafe, due to the number of invariants that aren't
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/// checked:
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///
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/// * `ptr` needs to have been previously allocated via [`String`]/`Vec<T>`
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||
/// (at least, it's highly likely to be incorrect if it wasn't).
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||
/// * `ptr`'s `T` needs to have the same size and alignment as it was allocated with.
|
||
/// * `length` needs to be less than or equal to `capacity`.
|
||
/// * `capacity` needs to be the capacity that the pointer was allocated with.
|
||
///
|
||
/// Violating these may cause problems like corrupting the allocator's
|
||
/// internal data structures. For example it is **not** safe
|
||
/// to build a `Vec<u8>` from a pointer to a C `char` array 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
|
||
///
|
||
/// ```
|
||
/// use std::ptr;
|
||
/// use std::mem;
|
||
///
|
||
/// fn main() {
|
||
/// let mut v = vec![1, 2, 3];
|
||
///
|
||
/// // Pull out the various important pieces of information about `v`
|
||
/// let p = v.as_mut_ptr();
|
||
/// let len = v.len();
|
||
/// let cap = v.capacity();
|
||
///
|
||
/// unsafe {
|
||
/// // Cast `v` into the void: no destructor run, so we are in
|
||
/// // complete control of the allocation to which `p` points.
|
||
/// mem::forget(v);
|
||
///
|
||
/// // Overwrite memory with 4, 5, 6
|
||
/// for i in 0..len as isize {
|
||
/// ptr::write(p.offset(i), 4 + i);
|
||
/// }
|
||
///
|
||
/// // Put everything back together into a Vec
|
||
/// let rebuilt = Vec::from_raw_parts(p, len, cap);
|
||
/// assert_eq!(rebuilt, [4, 5, 6]);
|
||
/// }
|
||
/// }
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub unsafe fn from_raw_parts(ptr: *mut T, length: usize, capacity: usize) -> Vec<T> {
|
||
Vec {
|
||
buf: RawVec::from_raw_parts(ptr, capacity),
|
||
len: length,
|
||
}
|
||
}
|
||
|
||
/// Returns the number of elements the vector can hold without
|
||
/// reallocating.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let vec: Vec<i32> = Vec::with_capacity(10);
|
||
/// assert_eq!(vec.capacity(), 10);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn capacity(&self) -> usize {
|
||
self.buf.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. After calling `reserve`, capacity will be
|
||
/// greater than or equal to `self.len() + additional`. Does nothing if
|
||
/// capacity is already sufficient.
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if the new capacity overflows `usize`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1];
|
||
/// vec.reserve(10);
|
||
/// assert!(vec.capacity() >= 11);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn reserve(&mut self, additional: usize) {
|
||
self.buf.reserve(self.len, additional);
|
||
}
|
||
|
||
/// Reserves the minimum capacity for exactly `additional` more elements to
|
||
/// be inserted in the given `Vec<T>`. After calling `reserve_exact`,
|
||
/// capacity will be greater than or equal to `self.len() + additional`.
|
||
/// Does nothing if the capacity is already sufficient.
|
||
///
|
||
/// Note that the allocator may give the collection more space than it
|
||
/// requests. Therefore capacity can not be relied upon to be precisely
|
||
/// minimal. Prefer `reserve` if future insertions are expected.
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if the new capacity overflows `usize`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1];
|
||
/// vec.reserve_exact(10);
|
||
/// assert!(vec.capacity() >= 11);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn reserve_exact(&mut self, additional: usize) {
|
||
self.buf.reserve_exact(self.len, additional);
|
||
}
|
||
|
||
/// Tries to reserve capacity for at least `additional` more elements to be inserted
|
||
/// in the given `Vec<T>`. The collection may reserve more space to avoid
|
||
/// frequent reallocations. After calling `reserve`, capacity will be
|
||
/// greater than or equal to `self.len() + additional`. Does nothing if
|
||
/// capacity is already sufficient.
|
||
///
|
||
/// # Errors
|
||
///
|
||
/// If the capacity overflows, or the allocator reports a failure, then an error
|
||
/// is returned.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// #![feature(try_reserve)]
|
||
/// use std::collections::CollectionAllocErr;
|
||
///
|
||
/// fn process_data(data: &[u32]) -> Result<Vec<u32>, CollectionAllocErr> {
|
||
/// let mut output = Vec::new();
|
||
///
|
||
/// // Pre-reserve the memory, exiting if we can't
|
||
/// output.try_reserve(data.len())?;
|
||
///
|
||
/// // Now we know this can't OOM in the middle of our complex work
|
||
/// output.extend(data.iter().map(|&val| {
|
||
/// val * 2 + 5 // very complicated
|
||
/// }));
|
||
///
|
||
/// Ok(output)
|
||
/// }
|
||
/// # process_data(&[1, 2, 3]).expect("why is the test harness OOMing on 12 bytes?");
|
||
/// ```
|
||
#[unstable(feature = "try_reserve", reason = "new API", issue="48043")]
|
||
pub fn try_reserve(&mut self, additional: usize) -> Result<(), CollectionAllocErr> {
|
||
self.buf.try_reserve(self.len, additional)
|
||
}
|
||
|
||
/// Tries to reserves the minimum capacity for exactly `additional` more elements to
|
||
/// be inserted in the given `Vec<T>`. After calling `reserve_exact`,
|
||
/// capacity will be greater than or equal to `self.len() + additional`.
|
||
/// Does nothing if the capacity is already sufficient.
|
||
///
|
||
/// Note that the allocator may give the collection more space than it
|
||
/// requests. Therefore capacity can not be relied upon to be precisely
|
||
/// minimal. Prefer `reserve` if future insertions are expected.
|
||
///
|
||
/// # Errors
|
||
///
|
||
/// If the capacity overflows, or the allocator reports a failure, then an error
|
||
/// is returned.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// #![feature(try_reserve)]
|
||
/// use std::collections::CollectionAllocErr;
|
||
///
|
||
/// fn process_data(data: &[u32]) -> Result<Vec<u32>, CollectionAllocErr> {
|
||
/// let mut output = Vec::new();
|
||
///
|
||
/// // Pre-reserve the memory, exiting if we can't
|
||
/// output.try_reserve(data.len())?;
|
||
///
|
||
/// // Now we know this can't OOM in the middle of our complex work
|
||
/// output.extend(data.iter().map(|&val| {
|
||
/// val * 2 + 5 // very complicated
|
||
/// }));
|
||
///
|
||
/// Ok(output)
|
||
/// }
|
||
/// # process_data(&[1, 2, 3]).expect("why is the test harness OOMing on 12 bytes?");
|
||
/// ```
|
||
#[unstable(feature = "try_reserve", reason = "new API", issue="48043")]
|
||
pub fn try_reserve_exact(&mut self, additional: usize) -> Result<(), CollectionAllocErr> {
|
||
self.buf.try_reserve_exact(self.len, additional)
|
||
}
|
||
|
||
/// Shrinks the capacity of the vector as much as possible.
|
||
///
|
||
/// It will drop down as close as possible to the length but the allocator
|
||
/// may still inform the vector that there is space for a few more elements.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = Vec::with_capacity(10);
|
||
/// vec.extend([1, 2, 3].iter().cloned());
|
||
/// assert_eq!(vec.capacity(), 10);
|
||
/// vec.shrink_to_fit();
|
||
/// assert!(vec.capacity() >= 3);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn shrink_to_fit(&mut self) {
|
||
if self.capacity() != self.len {
|
||
self.buf.shrink_to_fit(self.len);
|
||
}
|
||
}
|
||
|
||
/// Shrinks the capacity of the vector with a lower bound.
|
||
///
|
||
/// The capacity will remain at least as large as both the length
|
||
/// and the supplied value.
|
||
///
|
||
/// Panics if the current capacity is smaller than the supplied
|
||
/// minimum capacity.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// #![feature(shrink_to)]
|
||
/// let mut vec = Vec::with_capacity(10);
|
||
/// vec.extend([1, 2, 3].iter().cloned());
|
||
/// assert_eq!(vec.capacity(), 10);
|
||
/// vec.shrink_to(4);
|
||
/// assert!(vec.capacity() >= 4);
|
||
/// vec.shrink_to(0);
|
||
/// assert!(vec.capacity() >= 3);
|
||
/// ```
|
||
#[unstable(feature = "shrink_to", reason = "new API", issue="0")]
|
||
pub fn shrink_to(&mut self, min_capacity: usize) {
|
||
self.buf.shrink_to_fit(cmp::max(self.len, min_capacity));
|
||
}
|
||
|
||
/// Converts the vector into [`Box<[T]>`][owned slice].
|
||
///
|
||
/// Note that this will drop any excess capacity.
|
||
///
|
||
/// [owned slice]: ../../std/boxed/struct.Box.html
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let v = vec![1, 2, 3];
|
||
///
|
||
/// let slice = v.into_boxed_slice();
|
||
/// ```
|
||
///
|
||
/// Any excess capacity is removed:
|
||
///
|
||
/// ```
|
||
/// let mut vec = Vec::with_capacity(10);
|
||
/// vec.extend([1, 2, 3].iter().cloned());
|
||
///
|
||
/// assert_eq!(vec.capacity(), 10);
|
||
/// let slice = vec.into_boxed_slice();
|
||
/// assert_eq!(slice.into_vec().capacity(), 3);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn into_boxed_slice(mut self) -> Box<[T]> {
|
||
unsafe {
|
||
self.shrink_to_fit();
|
||
let buf = ptr::read(&self.buf);
|
||
mem::forget(self);
|
||
buf.into_box()
|
||
}
|
||
}
|
||
|
||
/// Shortens the vector, keeping the first `len` elements and dropping
|
||
/// the rest.
|
||
///
|
||
/// If `len` is greater than the vector's current length, this has no
|
||
/// effect.
|
||
///
|
||
/// The [`drain`] method can emulate `truncate`, but causes the excess
|
||
/// elements to be returned instead of dropped.
|
||
///
|
||
/// Note that this method has no effect on the allocated capacity
|
||
/// of the vector.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Truncating a five element vector to two elements:
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1, 2, 3, 4, 5];
|
||
/// vec.truncate(2);
|
||
/// assert_eq!(vec, [1, 2]);
|
||
/// ```
|
||
///
|
||
/// No truncation occurs when `len` is greater than the vector's current
|
||
/// length:
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1, 2, 3];
|
||
/// vec.truncate(8);
|
||
/// assert_eq!(vec, [1, 2, 3]);
|
||
/// ```
|
||
///
|
||
/// Truncating when `len == 0` is equivalent to calling the [`clear`]
|
||
/// method.
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1, 2, 3];
|
||
/// vec.truncate(0);
|
||
/// assert_eq!(vec, []);
|
||
/// ```
|
||
///
|
||
/// [`clear`]: #method.clear
|
||
/// [`drain`]: #method.drain
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn truncate(&mut self, len: usize) {
|
||
unsafe {
|
||
// drop any extra elements
|
||
while len < self.len {
|
||
// decrement len before the drop_in_place(), so a panic on Drop
|
||
// doesn't re-drop the just-failed value.
|
||
self.len -= 1;
|
||
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]
|
||
#[stable(feature = "vec_as_slice", since = "1.7.0")]
|
||
pub fn as_slice(&self) -> &[T] {
|
||
self
|
||
}
|
||
|
||
/// Extracts a mutable slice of the entire vector.
|
||
///
|
||
/// Equivalent to `&mut s[..]`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// use std::io::{self, Read};
|
||
/// let mut buffer = vec![0; 3];
|
||
/// io::repeat(0b101).read_exact(buffer.as_mut_slice()).unwrap();
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "vec_as_slice", since = "1.7.0")]
|
||
pub fn as_mut_slice(&mut self) -> &mut [T] {
|
||
self
|
||
}
|
||
|
||
/// Sets the length of a vector.
|
||
///
|
||
/// This will explicitly set the size of the vector, without actually
|
||
/// modifying its buffers, so it is up to the caller to ensure that the
|
||
/// vector is actually the specified size.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// 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 {
|
||
/// vec.set_len(4);
|
||
/// }
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub unsafe fn set_len(&mut self, len: usize) {
|
||
self.len = len;
|
||
}
|
||
|
||
/// Removes an element from the vector and returns it.
|
||
///
|
||
/// The removed element is replaced by the last element of the vector.
|
||
///
|
||
/// This does not preserve ordering, but is O(1).
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if `index` is out of bounds.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut v = vec!["foo", "bar", "baz", "qux"];
|
||
///
|
||
/// assert_eq!(v.swap_remove(1), "bar");
|
||
/// assert_eq!(v, ["foo", "qux", "baz"]);
|
||
///
|
||
/// assert_eq!(v.swap_remove(0), "foo");
|
||
/// assert_eq!(v, ["baz", "qux"]);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn swap_remove(&mut self, index: usize) -> T {
|
||
let length = self.len();
|
||
self.swap(index, length - 1);
|
||
self.pop().unwrap()
|
||
}
|
||
|
||
/// Inserts an element at position `index` within the vector, shifting all
|
||
/// elements after it to the right.
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if `index > len`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1, 2, 3];
|
||
/// vec.insert(1, 4);
|
||
/// assert_eq!(vec, [1, 4, 2, 3]);
|
||
/// vec.insert(4, 5);
|
||
/// assert_eq!(vec, [1, 4, 2, 3, 5]);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn insert(&mut self, index: usize, element: T) {
|
||
let len = self.len();
|
||
assert!(index <= len);
|
||
|
||
// space for the new element
|
||
if len == self.buf.cap() {
|
||
self.buf.double();
|
||
}
|
||
|
||
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);
|
||
// Write it in, overwriting the first copy of the `index`th
|
||
// element.
|
||
ptr::write(p, element);
|
||
}
|
||
self.set_len(len + 1);
|
||
}
|
||
}
|
||
|
||
/// Removes and returns the element at position `index` within the vector,
|
||
/// shifting all elements after it to the left.
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if `index` is out of bounds.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut v = vec![1, 2, 3];
|
||
/// assert_eq!(v.remove(1), 2);
|
||
/// assert_eq!(v, [1, 3]);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn remove(&mut self, index: usize) -> T {
|
||
let len = self.len();
|
||
assert!(index < len);
|
||
unsafe {
|
||
// infallible
|
||
let ret;
|
||
{
|
||
// the place we are taking from.
|
||
let ptr = self.as_mut_ptr().offset(index as isize);
|
||
// copy it out, unsafely having a copy of the value on
|
||
// the stack and in the vector at the same time.
|
||
ret = ptr::read(ptr);
|
||
|
||
// Shift everything down to fill in that spot.
|
||
ptr::copy(ptr.offset(1), ptr, len - index - 1);
|
||
}
|
||
self.set_len(len - 1);
|
||
ret
|
||
}
|
||
}
|
||
|
||
/// Retains only the elements specified by the predicate.
|
||
///
|
||
/// In other words, remove all elements `e` such that `f(&e)` returns `false`.
|
||
/// This method operates in place and preserves the order of the retained
|
||
/// elements.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1, 2, 3, 4];
|
||
/// vec.retain(|&x| x%2 == 0);
|
||
/// assert_eq!(vec, [2, 4]);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn retain<F>(&mut self, mut f: F)
|
||
where F: FnMut(&T) -> bool
|
||
{
|
||
self.drain_filter(|x| !f(x));
|
||
}
|
||
|
||
/// Removes all but the first of consecutive elements in the vector that resolve to the same
|
||
/// key.
|
||
///
|
||
/// If the vector is sorted, this removes all duplicates.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![10, 20, 21, 30, 20];
|
||
///
|
||
/// vec.dedup_by_key(|i| *i / 10);
|
||
///
|
||
/// assert_eq!(vec, [10, 20, 30, 20]);
|
||
/// ```
|
||
#[stable(feature = "dedup_by", since = "1.16.0")]
|
||
#[inline]
|
||
pub fn dedup_by_key<F, K>(&mut self, mut key: F) where F: FnMut(&mut T) -> K, K: PartialEq {
|
||
self.dedup_by(|a, b| key(a) == key(b))
|
||
}
|
||
|
||
/// Removes all but the first of consecutive elements in the vector satisfying a given equality
|
||
/// relation.
|
||
///
|
||
/// The `same_bucket` function is passed references to two elements from the vector, and
|
||
/// returns `true` if the elements compare equal, or `false` if they do not. The elements are
|
||
/// passed in opposite order from their order in the vector, so if `same_bucket(a, b)` returns
|
||
/// `true`, `a` is removed.
|
||
///
|
||
/// If the vector is sorted, this removes all duplicates.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec!["foo", "bar", "Bar", "baz", "bar"];
|
||
///
|
||
/// vec.dedup_by(|a, b| a.eq_ignore_ascii_case(b));
|
||
///
|
||
/// assert_eq!(vec, ["foo", "bar", "baz", "bar"]);
|
||
/// ```
|
||
#[stable(feature = "dedup_by", since = "1.16.0")]
|
||
pub fn dedup_by<F>(&mut self, 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
|
||
///
|
||
/// Panics if the number of elements in the vector overflows a `usize`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1, 2];
|
||
/// vec.push(3);
|
||
/// assert_eq!(vec, [1, 2, 3]);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn push(&mut self, value: T) {
|
||
// This will panic or abort if we would allocate > isize::MAX bytes
|
||
// or if the length increment would overflow for zero-sized types.
|
||
if self.len == self.buf.cap() {
|
||
self.buf.double();
|
||
}
|
||
unsafe {
|
||
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.
|
||
///
|
||
/// [`None`]: ../../std/option/enum.Option.html#variant.None
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1, 2, 3];
|
||
/// assert_eq!(vec.pop(), Some(3));
|
||
/// assert_eq!(vec, [1, 2]);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn pop(&mut self) -> Option<T> {
|
||
if self.len == 0 {
|
||
None
|
||
} else {
|
||
unsafe {
|
||
self.len -= 1;
|
||
Some(ptr::read(self.get_unchecked(self.len())))
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Moves all the elements of `other` into `Self`, leaving `other` empty.
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if the number of elements in the vector overflows a `usize`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1, 2, 3];
|
||
/// let mut vec2 = vec![4, 5, 6];
|
||
/// vec.append(&mut vec2);
|
||
/// assert_eq!(vec, [1, 2, 3, 4, 5, 6]);
|
||
/// assert_eq!(vec2, []);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "append", since = "1.4.0")]
|
||
pub fn append(&mut self, other: &mut Self) {
|
||
unsafe {
|
||
self.append_elements(other.as_slice() as _);
|
||
other.set_len(0);
|
||
}
|
||
}
|
||
|
||
/// Appends elements to `Self` from other buffer.
|
||
#[inline]
|
||
unsafe fn append_elements(&mut self, other: *const [T]) {
|
||
let count = (*other).len();
|
||
self.reserve(count);
|
||
let len = self.len();
|
||
ptr::copy_nonoverlapping(other as *const T, self.get_unchecked_mut(len), count);
|
||
self.len += count;
|
||
}
|
||
|
||
/// Creates a draining iterator that removes the specified range in the vector
|
||
/// and yields the removed items.
|
||
///
|
||
/// Note 1: The element range is removed even if the iterator is only
|
||
/// partially consumed or not consumed at all.
|
||
///
|
||
/// Note 2: It is unspecified how many elements are removed from the vector
|
||
/// if the `Drain` value is leaked.
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if the starting point is greater than the end point or if
|
||
/// the end point is greater than the length of the vector.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut v = vec![1, 2, 3];
|
||
/// let u: Vec<_> = v.drain(1..).collect();
|
||
/// assert_eq!(v, &[1]);
|
||
/// assert_eq!(u, &[2, 3]);
|
||
///
|
||
/// // A full range clears the vector
|
||
/// v.drain(..);
|
||
/// assert_eq!(v, &[]);
|
||
/// ```
|
||
#[stable(feature = "drain", since = "1.6.0")]
|
||
pub fn drain<R>(&mut self, range: R) -> Drain<T>
|
||
where R: RangeBounds<usize>
|
||
{
|
||
// Memory safety
|
||
//
|
||
// When the Drain is first created, it shortens the length of
|
||
// the source vector to make sure no uninitialized or moved-from elements
|
||
// are accessible at all if the Drain's destructor never gets to run.
|
||
//
|
||
// Drain will ptr::read out the values to remove.
|
||
// When finished, remaining tail of the vec is copied back to cover
|
||
// the hole, and the vector length is restored to the new length.
|
||
//
|
||
let len = self.len();
|
||
let start = match range.start() {
|
||
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 {
|
||
// 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 {
|
||
tail_start: end,
|
||
tail_len: len - end,
|
||
iter: range_slice.iter(),
|
||
vec: NonNull::from(self),
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Clears the vector, removing all values.
|
||
///
|
||
/// Note that this method has no effect on the allocated capacity
|
||
/// of the vector.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut v = vec![1, 2, 3];
|
||
///
|
||
/// v.clear();
|
||
///
|
||
/// assert!(v.is_empty());
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn clear(&mut self) {
|
||
self.truncate(0)
|
||
}
|
||
|
||
/// Returns the number of elements in the vector, also referred to
|
||
/// as its 'length'.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let a = vec![1, 2, 3];
|
||
/// assert_eq!(a.len(), 3);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn len(&self) -> usize {
|
||
self.len
|
||
}
|
||
|
||
/// Returns `true` if the vector contains no elements.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut v = Vec::new();
|
||
/// assert!(v.is_empty());
|
||
///
|
||
/// v.push(1);
|
||
/// assert!(!v.is_empty());
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn is_empty(&self) -> bool {
|
||
self.len() == 0
|
||
}
|
||
|
||
/// Splits the collection into two at the given index.
|
||
///
|
||
/// Returns a newly allocated `Self`. `self` contains elements `[0, at)`,
|
||
/// and the returned `Self` contains elements `[at, len)`.
|
||
///
|
||
/// Note that the capacity of `self` does not change.
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if `at > len`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1,2,3];
|
||
/// let vec2 = vec.split_off(1);
|
||
/// assert_eq!(vec, [1]);
|
||
/// assert_eq!(vec2, [2, 3]);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "split_off", since = "1.4.0")]
|
||
pub fn split_off(&mut self, at: usize) -> Self {
|
||
assert!(at <= self.len(), "`at` out of bounds");
|
||
|
||
let other_len = self.len - at;
|
||
let mut other = Vec::with_capacity(other_len);
|
||
|
||
// Unsafely `set_len` and copy items to `other`.
|
||
unsafe {
|
||
self.set_len(at);
|
||
other.set_len(other_len);
|
||
|
||
ptr::copy_nonoverlapping(self.as_ptr().offset(at as isize),
|
||
other.as_mut_ptr(),
|
||
other.len());
|
||
}
|
||
other
|
||
}
|
||
|
||
/// Resizes the `Vec` in-place so that `len` is equal to `new_len`.
|
||
///
|
||
/// If `new_len` is greater than `len`, the `Vec` is extended by the
|
||
/// difference, with each additional slot filled with the result of
|
||
/// calling the closure `f`. The return values from `f` will end up
|
||
/// in the `Vec` in the order they have been generated.
|
||
///
|
||
/// If `new_len` is less than `len`, the `Vec` is simply truncated.
|
||
///
|
||
/// This method uses a closure to create new values on every push. If
|
||
/// you'd rather [`Clone`] a given value, use [`resize`]. If you want
|
||
/// to use the [`Default`] trait to generate values, you can pass
|
||
/// [`Default::default()`] as the second argument..
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// #![feature(vec_resize_with)]
|
||
///
|
||
/// let mut vec = vec![1, 2, 3];
|
||
/// vec.resize_with(5, Default::default);
|
||
/// assert_eq!(vec, [1, 2, 3, 0, 0]);
|
||
///
|
||
/// let mut vec = vec![];
|
||
/// let mut p = 1;
|
||
/// vec.resize_with(4, || { p *= 2; p });
|
||
/// assert_eq!(vec, [2, 4, 8, 16]);
|
||
/// ```
|
||
///
|
||
/// [`resize`]: #method.resize
|
||
/// [`Clone`]: ../../std/clone/trait.Clone.html
|
||
#[unstable(feature = "vec_resize_with", issue = "41758")]
|
||
pub fn resize_with<F>(&mut self, new_len: usize, f: F)
|
||
where F: FnMut() -> T
|
||
{
|
||
let len = self.len();
|
||
if new_len > len {
|
||
self.extend_with(new_len - len, ExtendFunc(f));
|
||
} else {
|
||
self.truncate(new_len);
|
||
}
|
||
}
|
||
}
|
||
|
||
impl<T: Clone> Vec<T> {
|
||
/// Resizes the `Vec` in-place so that `len` is equal to `new_len`.
|
||
///
|
||
/// If `new_len` is greater than `len`, the `Vec` is extended by the
|
||
/// difference, with each additional slot filled with `value`.
|
||
/// If `new_len` is less than `len`, the `Vec` is simply truncated.
|
||
///
|
||
/// This method requires [`Clone`] to be able clone the passed value. If
|
||
/// you need more flexibility (or want to rely on [`Default`] instead of
|
||
/// [`Clone`]), use [`resize_with`].
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec!["hello"];
|
||
/// vec.resize(3, "world");
|
||
/// assert_eq!(vec, ["hello", "world", "world"]);
|
||
///
|
||
/// let mut vec = vec![1, 2, 3, 4];
|
||
/// vec.resize(2, 0);
|
||
/// assert_eq!(vec, [1, 2]);
|
||
/// ```
|
||
///
|
||
/// [`Clone`]: ../../std/clone/trait.Clone.html
|
||
/// [`Default`]: ../../std/default/trait.Default.html
|
||
/// [`resize_with`]: #method.resize_with
|
||
#[stable(feature = "vec_resize", since = "1.5.0")]
|
||
pub fn resize(&mut self, new_len: usize, value: T) {
|
||
let len = self.len();
|
||
|
||
if new_len > len {
|
||
self.extend_with(new_len - len, ExtendElement(value))
|
||
} else {
|
||
self.truncate(new_len);
|
||
}
|
||
}
|
||
|
||
/// Clones and appends all elements in a slice to the `Vec`.
|
||
///
|
||
/// Iterates over the slice `other`, clones each element, and then appends
|
||
/// it to this `Vec`. The `other` vector is traversed in-order.
|
||
///
|
||
/// Note that this function is same as [`extend`] except that it is
|
||
/// specialized to work with slices instead. If and when Rust gets
|
||
/// specialization this function will likely be deprecated (but still
|
||
/// available).
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1];
|
||
/// vec.extend_from_slice(&[2, 3, 4]);
|
||
/// assert_eq!(vec, [1, 2, 3, 4]);
|
||
/// ```
|
||
///
|
||
/// [`extend`]: #method.extend
|
||
#[stable(feature = "vec_extend_from_slice", since = "1.6.0")]
|
||
pub fn extend_from_slice(&mut self, other: &[T]) {
|
||
self.spec_extend(other.iter())
|
||
}
|
||
}
|
||
|
||
impl<T: Default> Vec<T> {
|
||
/// Resizes the `Vec` in-place so that `len` is equal to `new_len`.
|
||
///
|
||
/// If `new_len` is greater than `len`, the `Vec` is extended by the
|
||
/// difference, with each additional slot filled with [`Default::default()`].
|
||
/// If `new_len` is less than `len`, the `Vec` is simply truncated.
|
||
///
|
||
/// This method uses [`Default`] to create new values on every push. If
|
||
/// you'd rather [`Clone`] a given value, use [`resize`].
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// #![feature(vec_resize_default)]
|
||
///
|
||
/// let mut vec = vec![1, 2, 3];
|
||
/// vec.resize_default(5);
|
||
/// assert_eq!(vec, [1, 2, 3, 0, 0]);
|
||
///
|
||
/// let mut vec = vec![1, 2, 3, 4];
|
||
/// vec.resize_default(2);
|
||
/// assert_eq!(vec, [1, 2]);
|
||
/// ```
|
||
///
|
||
/// [`resize`]: #method.resize
|
||
/// [`Default::default()`]: ../../std/default/trait.Default.html#tymethod.default
|
||
/// [`Default`]: ../../std/default/trait.Default.html
|
||
/// [`Clone`]: ../../std/clone/trait.Clone.html
|
||
#[unstable(feature = "vec_resize_default", issue = "41758")]
|
||
pub fn resize_default(&mut self, new_len: usize) {
|
||
let len = self.len();
|
||
|
||
if new_len > len {
|
||
self.extend_with(new_len - len, ExtendDefault);
|
||
} else {
|
||
self.truncate(new_len);
|
||
}
|
||
}
|
||
}
|
||
|
||
// This code generalises `extend_with_{element,default}`.
|
||
trait ExtendWith<T> {
|
||
fn next(&mut self) -> T;
|
||
fn last(self) -> T;
|
||
}
|
||
|
||
struct ExtendElement<T>(T);
|
||
impl<T: Clone> ExtendWith<T> for ExtendElement<T> {
|
||
fn next(&mut self) -> T { self.0.clone() }
|
||
fn last(self) -> T { self.0 }
|
||
}
|
||
|
||
struct ExtendDefault;
|
||
impl<T: Default> ExtendWith<T> for ExtendDefault {
|
||
fn next(&mut self) -> T { Default::default() }
|
||
fn last(self) -> T { Default::default() }
|
||
}
|
||
|
||
struct ExtendFunc<F>(F);
|
||
impl<T, F: FnMut() -> T> ExtendWith<T> for ExtendFunc<F> {
|
||
fn next(&mut self) -> T { (self.0)() }
|
||
fn last(mut self) -> T { (self.0)() }
|
||
}
|
||
|
||
impl<T> Vec<T> {
|
||
/// Extend the vector by `n` values, using the given generator.
|
||
fn extend_with<E: ExtendWith<T>>(&mut self, n: usize, mut value: E) {
|
||
self.reserve(n);
|
||
|
||
unsafe {
|
||
let mut ptr = self.as_mut_ptr().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.
|
||
///
|
||
/// If the vector is sorted, this removes all duplicates.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut vec = vec![1, 2, 2, 3, 2];
|
||
///
|
||
/// vec.dedup();
|
||
///
|
||
/// assert_eq!(vec, [1, 2, 3, 2]);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn dedup(&mut self) {
|
||
self.dedup_by(|a, b| a == b)
|
||
}
|
||
|
||
/// 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 = self.iter().position(|x| *x == *item)?;
|
||
Some(self.remove(pos))
|
||
}
|
||
}
|
||
|
||
////////////////////////////////////////////////////////////////////////////////
|
||
// Internal methods and functions
|
||
////////////////////////////////////////////////////////////////////////////////
|
||
|
||
#[doc(hidden)]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn from_elem<T: Clone>(elem: T, n: usize) -> Vec<T> {
|
||
<T as SpecFromElem>::from_elem(elem, n)
|
||
}
|
||
|
||
// Specialization trait used for Vec::from_elem
|
||
trait SpecFromElem: Sized {
|
||
fn from_elem(elem: Self, n: usize) -> Vec<Self>;
|
||
}
|
||
|
||
impl<T: Clone> SpecFromElem for T {
|
||
default fn from_elem(elem: Self, n: usize) -> Vec<Self> {
|
||
let mut v = Vec::with_capacity(n);
|
||
v.extend_with(n, ExtendElement(elem));
|
||
v
|
||
}
|
||
}
|
||
|
||
impl SpecFromElem for u8 {
|
||
#[inline]
|
||
fn from_elem(elem: u8, n: usize) -> Vec<u8> {
|
||
if elem == 0 {
|
||
return Vec {
|
||
buf: RawVec::with_capacity_zeroed(n),
|
||
len: n,
|
||
}
|
||
}
|
||
unsafe {
|
||
let mut v = Vec::with_capacity(n);
|
||
ptr::write_bytes(v.as_mut_ptr(), elem, n);
|
||
v.set_len(n);
|
||
v
|
||
}
|
||
}
|
||
}
|
||
|
||
impl<T: Clone + IsZero> SpecFromElem for T {
|
||
#[inline]
|
||
fn from_elem(elem: T, n: usize) -> Vec<T> {
|
||
if elem.is_zero() {
|
||
return Vec {
|
||
buf: RawVec::with_capacity_zeroed(n),
|
||
len: n,
|
||
}
|
||
}
|
||
let mut v = Vec::with_capacity(n);
|
||
v.extend_with(n, ExtendElement(elem));
|
||
v
|
||
}
|
||
}
|
||
|
||
unsafe trait IsZero {
|
||
/// Whether this value is zero
|
||
fn is_zero(&self) -> bool;
|
||
}
|
||
|
||
macro_rules! impl_is_zero {
|
||
($t: ty, $is_zero: expr) => {
|
||
unsafe impl IsZero for $t {
|
||
#[inline]
|
||
fn is_zero(&self) -> bool {
|
||
$is_zero(*self)
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
impl_is_zero!(i8, |x| x == 0);
|
||
impl_is_zero!(i16, |x| x == 0);
|
||
impl_is_zero!(i32, |x| x == 0);
|
||
impl_is_zero!(i64, |x| x == 0);
|
||
impl_is_zero!(i128, |x| x == 0);
|
||
impl_is_zero!(isize, |x| x == 0);
|
||
|
||
impl_is_zero!(u16, |x| x == 0);
|
||
impl_is_zero!(u32, |x| x == 0);
|
||
impl_is_zero!(u64, |x| x == 0);
|
||
impl_is_zero!(u128, |x| x == 0);
|
||
impl_is_zero!(usize, |x| x == 0);
|
||
|
||
impl_is_zero!(char, |x| x == '\0');
|
||
|
||
impl_is_zero!(f32, |x: f32| x.to_bits() == 0);
|
||
impl_is_zero!(f64, |x: f64| x.to_bits() == 0);
|
||
|
||
unsafe impl<T: ?Sized> IsZero for *const T {
|
||
#[inline]
|
||
fn is_zero(&self) -> bool {
|
||
(*self).is_null()
|
||
}
|
||
}
|
||
|
||
unsafe impl<T: ?Sized> IsZero for *mut T {
|
||
#[inline]
|
||
fn is_zero(&self) -> bool {
|
||
(*self).is_null()
|
||
}
|
||
}
|
||
|
||
|
||
////////////////////////////////////////////////////////////////////////////////
|
||
// Common trait implementations for Vec
|
||
////////////////////////////////////////////////////////////////////////////////
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: Clone> Clone for Vec<T> {
|
||
#[cfg(not(test))]
|
||
fn clone(&self) -> Vec<T> {
|
||
<[T]>::to_vec(&**self)
|
||
}
|
||
|
||
// HACK(japaric): with cfg(test) the inherent `[T]::to_vec` method, which is
|
||
// required for this method definition, is not available. Instead use the
|
||
// `slice::to_vec` function which is only available with cfg(test)
|
||
// NB see the slice::hack module in slice.rs for more information
|
||
#[cfg(test)]
|
||
fn clone(&self) -> Vec<T> {
|
||
::slice::to_vec(&**self)
|
||
}
|
||
|
||
fn clone_from(&mut self, other: &Vec<T>) {
|
||
other.as_slice().clone_into(self);
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: Hash> Hash for Vec<T> {
|
||
#[inline]
|
||
fn hash<H: hash::Hasher>(&self, state: &mut H) {
|
||
Hash::hash(&**self, state)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"]
|
||
impl<T, I> Index<I> for Vec<T>
|
||
where
|
||
I: ::core::slice::SliceIndex<[T]>,
|
||
{
|
||
type Output = I::Output;
|
||
|
||
#[inline]
|
||
fn index(&self, index: I) -> &Self::Output {
|
||
Index::index(&**self, index)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[rustc_on_unimplemented = "vector indices are of type `usize` or ranges of `usize`"]
|
||
impl<T, I> IndexMut<I> for Vec<T>
|
||
where
|
||
I: ::core::slice::SliceIndex<[T]>,
|
||
{
|
||
#[inline]
|
||
fn index_mut(&mut self, index: I) -> &mut Self::Output {
|
||
IndexMut::index_mut(&mut **self, index)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T> ops::Deref for Vec<T> {
|
||
type Target = [T];
|
||
|
||
fn deref(&self) -> &[T] {
|
||
unsafe {
|
||
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: NonNull::new_unchecked(begin),
|
||
phantom: PhantomData,
|
||
cap,
|
||
ptr: begin,
|
||
end,
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<'a, T> IntoIterator for &'a Vec<T> {
|
||
type Item = &'a T;
|
||
type IntoIter = slice::Iter<'a, T>;
|
||
|
||
fn into_iter(self) -> slice::Iter<'a, T> {
|
||
self.iter()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<'a, T> IntoIterator for &'a mut Vec<T> {
|
||
type Item = &'a mut T;
|
||
type IntoIter = slice::IterMut<'a, T>;
|
||
|
||
fn into_iter(self) -> slice::IterMut<'a, T> {
|
||
self.iter_mut()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T> Extend<T> for Vec<T> {
|
||
#[inline]
|
||
fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I) {
|
||
<Self as SpecExtend<T, I::IntoIter>>::spec_extend(self, iter.into_iter())
|
||
}
|
||
}
|
||
|
||
// Specialization trait used for Vec::from_iter and Vec::extend
|
||
trait SpecExtend<T, I> {
|
||
fn from_iter(iter: I) -> Self;
|
||
fn spec_extend(&mut self, iter: I);
|
||
}
|
||
|
||
impl<T, I> SpecExtend<T, I> for Vec<T>
|
||
where I: Iterator<Item=T>,
|
||
{
|
||
default fn from_iter(mut iterator: I) -> Self {
|
||
// Unroll the first iteration, as the vector is going to be
|
||
// expanded on this iteration in every case when the iterable is not
|
||
// empty, but the loop in extend_desugared() is not going to see the
|
||
// vector being full in the few subsequent loop iterations.
|
||
// So we get better branch prediction.
|
||
let mut vector = match iterator.next() {
|
||
None => return Vec::new(),
|
||
Some(element) => {
|
||
let (lower, _) = iterator.size_hint();
|
||
let mut vector = Vec::with_capacity(lower.saturating_add(1));
|
||
unsafe {
|
||
ptr::write(vector.get_unchecked_mut(0), element);
|
||
vector.set_len(1);
|
||
}
|
||
vector
|
||
}
|
||
};
|
||
<Vec<T> as SpecExtend<T, I>>::spec_extend(&mut vector, iterator);
|
||
vector
|
||
}
|
||
|
||
default fn spec_extend(&mut self, iter: I) {
|
||
self.extend_desugared(iter)
|
||
}
|
||
}
|
||
|
||
impl<T, I> SpecExtend<T, I> for Vec<T>
|
||
where I: TrustedLen<Item=T>,
|
||
{
|
||
default fn from_iter(iterator: I) -> Self {
|
||
let mut vector = Vec::new();
|
||
vector.spec_extend(iterator);
|
||
vector
|
||
}
|
||
|
||
default fn spec_extend(&mut self, iterator: I) {
|
||
// This is the case for a TrustedLen iterator.
|
||
let (low, high) = iterator.size_hint();
|
||
if let Some(high_value) = high {
|
||
debug_assert_eq!(low, high_value,
|
||
"TrustedLen iterator's size hint is not exact: {:?}",
|
||
(low, high));
|
||
}
|
||
if let Some(additional) = high {
|
||
self.reserve(additional);
|
||
unsafe {
|
||
let mut ptr = self.as_mut_ptr().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
|
||
}
|
||
}
|
||
|
||
fn spec_extend(&mut self, mut iterator: IntoIter<T>) {
|
||
unsafe {
|
||
self.append_elements(iterator.as_slice() as _);
|
||
}
|
||
iterator.ptr = iterator.end;
|
||
}
|
||
}
|
||
|
||
impl<'a, T: 'a, I> SpecExtend<&'a T, I> for Vec<T>
|
||
where I: Iterator<Item=&'a T>,
|
||
T: Clone,
|
||
{
|
||
default fn from_iter(iterator: I) -> Self {
|
||
SpecExtend::from_iter(iterator.cloned())
|
||
}
|
||
|
||
default fn spec_extend(&mut self, iterator: I) {
|
||
self.spec_extend(iterator.cloned())
|
||
}
|
||
}
|
||
|
||
impl<'a, T: 'a> SpecExtend<&'a T, slice::Iter<'a, T>> for Vec<T>
|
||
where T: Copy,
|
||
{
|
||
fn spec_extend(&mut self, iterator: slice::Iter<'a, T>) {
|
||
let slice = iterator.as_slice();
|
||
self.reserve(slice.len());
|
||
unsafe {
|
||
let len = self.len();
|
||
self.set_len(len + slice.len());
|
||
self.get_unchecked_mut(len..).copy_from_slice(slice);
|
||
}
|
||
}
|
||
}
|
||
|
||
impl<T> Vec<T> {
|
||
fn extend_desugared<I: Iterator<Item = T>>(&mut self, mut iterator: I) {
|
||
// This is the case for a general iterator.
|
||
//
|
||
// This function should be the moral equivalent of:
|
||
//
|
||
// for item in iterator {
|
||
// self.push(item);
|
||
// }
|
||
while let Some(element) = iterator.next() {
|
||
let len = self.len();
|
||
if len == self.capacity() {
|
||
let (lower, _) = iterator.size_hint();
|
||
self.reserve(lower.saturating_add(1));
|
||
}
|
||
unsafe {
|
||
ptr::write(self.get_unchecked_mut(len), element);
|
||
// NB can't overflow since we would have had to alloc the address space
|
||
self.set_len(len + 1);
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Creates a splicing iterator that replaces the specified range in the vector
|
||
/// with the given `replace_with` iterator and yields the removed items.
|
||
/// `replace_with` does not need to be the same length as `range`.
|
||
///
|
||
/// 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 mut v = vec![1, 2, 3];
|
||
/// let new = [7, 8];
|
||
/// let u: Vec<_> = v.splice(..2, new.iter().cloned()).collect();
|
||
/// assert_eq!(v, &[7, 8, 3]);
|
||
/// assert_eq!(u, &[1, 2]);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "vec_splice", since = "1.21.0")]
|
||
pub fn splice<R, I>(&mut self, range: R, replace_with: I) -> Splice<I::IntoIter>
|
||
where R: RangeBounds<usize>, I: IntoIterator<Item=T>
|
||
{
|
||
Splice {
|
||
drain: self.drain(range),
|
||
replace_with: replace_with.into_iter(),
|
||
}
|
||
}
|
||
|
||
/// Creates an iterator which uses a closure to determine if an element should be removed.
|
||
///
|
||
/// If the closure returns true, then the element is removed and yielded.
|
||
/// If the closure returns false, the element will remain in the vector and will not be yielded
|
||
/// by the iterator.
|
||
///
|
||
/// Using this method is equivalent to the following code:
|
||
///
|
||
/// ```
|
||
/// # let some_predicate = |x: &mut i32| { *x == 2 || *x == 3 || *x == 6 };
|
||
/// # let mut vec = vec![1, 2, 3, 4, 5, 6];
|
||
/// let mut i = 0;
|
||
/// while i != vec.len() {
|
||
/// if some_predicate(&mut vec[i]) {
|
||
/// let val = vec.remove(i);
|
||
/// // your code here
|
||
/// } else {
|
||
/// i += 1;
|
||
/// }
|
||
/// }
|
||
///
|
||
/// # assert_eq!(vec, vec![1, 4, 5]);
|
||
/// ```
|
||
///
|
||
/// But `drain_filter` is easier to use. `drain_filter` is also more efficient,
|
||
/// because it can backshift the elements of the array in bulk.
|
||
///
|
||
/// Note that `drain_filter` also lets you mutate every element in the filter closure,
|
||
/// regardless of whether you choose to keep or remove it.
|
||
///
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Splitting an array into evens and odds, reusing the original allocation:
|
||
///
|
||
/// ```
|
||
/// #![feature(drain_filter)]
|
||
/// let mut numbers = vec![1, 2, 3, 4, 5, 6, 8, 9, 11, 13, 14, 15];
|
||
///
|
||
/// let evens = numbers.drain_filter(|x| *x % 2 == 0).collect::<Vec<_>>();
|
||
/// let odds = numbers;
|
||
///
|
||
/// assert_eq!(evens, vec![2, 4, 6, 8, 14]);
|
||
/// assert_eq!(odds, vec![1, 3, 5, 9, 11, 13, 15]);
|
||
/// ```
|
||
#[unstable(feature = "drain_filter", reason = "recently added", issue = "43244")]
|
||
pub fn drain_filter<F>(&mut self, filter: F) -> DrainFilter<T, F>
|
||
where F: FnMut(&mut T) -> bool,
|
||
{
|
||
let old_len = self.len();
|
||
|
||
// Guard against us getting leaked (leak amplification)
|
||
unsafe { self.set_len(0); }
|
||
|
||
DrainFilter {
|
||
vec: self,
|
||
idx: 0,
|
||
del: 0,
|
||
old_len,
|
||
pred: filter,
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Extend implementation that copies elements out of references before pushing them onto the Vec.
|
||
///
|
||
/// This implementation is specialized for slice iterators, where it uses [`copy_from_slice`] to
|
||
/// append the entire slice at once.
|
||
///
|
||
/// [`copy_from_slice`]: ../../std/primitive.slice.html#method.copy_from_slice
|
||
#[stable(feature = "extend_ref", since = "1.2.0")]
|
||
impl<'a, T: 'a + Copy> Extend<&'a T> for Vec<T> {
|
||
fn extend<I: IntoIterator<Item = &'a T>>(&mut self, iter: I) {
|
||
self.spec_extend(iter.into_iter())
|
||
}
|
||
}
|
||
|
||
macro_rules! __impl_slice_eq1 {
|
||
($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: &$Rhs) -> bool { self[..] != other[..] }
|
||
}
|
||
}
|
||
}
|
||
|
||
__impl_slice_eq1! { Vec<A>, Vec<B> }
|
||
__impl_slice_eq1! { Vec<A>, &'b [B] }
|
||
__impl_slice_eq1! { Vec<A>, &'b mut [B] }
|
||
__impl_slice_eq1! { Cow<'a, [A]>, &'b [B], Clone }
|
||
__impl_slice_eq1! { Cow<'a, [A]>, &'b mut [B], Clone }
|
||
__impl_slice_eq1! { Cow<'a, [A]>, Vec<B>, Clone }
|
||
|
||
macro_rules! array_impls {
|
||
($($N: expr)+) => {
|
||
$(
|
||
// NOTE: some less important impls are omitted to reduce code bloat
|
||
__impl_slice_eq1! { Vec<A>, [B; $N] }
|
||
__impl_slice_eq1! { Vec<A>, &'b [B; $N] }
|
||
// __impl_slice_eq1! { Vec<A>, &'b mut [B; $N] }
|
||
// __impl_slice_eq1! { Cow<'a, [A]>, [B; $N], Clone }
|
||
// __impl_slice_eq1! { Cow<'a, [A]>, &'b [B; $N], Clone }
|
||
// __impl_slice_eq1! { Cow<'a, [A]>, &'b mut [B; $N], Clone }
|
||
)+
|
||
}
|
||
}
|
||
|
||
array_impls! {
|
||
0 1 2 3 4 5 6 7 8 9
|
||
10 11 12 13 14 15 16 17 18 19
|
||
20 21 22 23 24 25 26 27 28 29
|
||
30 31 32
|
||
}
|
||
|
||
/// Implements comparison of vectors, lexicographically.
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: PartialOrd> PartialOrd for Vec<T> {
|
||
#[inline]
|
||
fn partial_cmp(&self, other: &Vec<T>) -> Option<Ordering> {
|
||
PartialOrd::partial_cmp(&**self, &**other)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: Eq> Eq for Vec<T> {}
|
||
|
||
/// Implements ordering of vectors, lexicographically.
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: Ord> Ord for Vec<T> {
|
||
#[inline]
|
||
fn cmp(&self, other: &Vec<T>) -> Ordering {
|
||
Ord::cmp(&**self, &**other)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
unsafe impl<#[may_dangle] T> Drop for Vec<T> {
|
||
fn drop(&mut self) {
|
||
unsafe {
|
||
// use drop for [T]
|
||
ptr::drop_in_place(&mut self[..]);
|
||
}
|
||
// RawVec handles deallocation
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T> Default for Vec<T> {
|
||
/// Creates an empty `Vec<T>`.
|
||
fn default() -> Vec<T> {
|
||
Vec::new()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: fmt::Debug> fmt::Debug for Vec<T> {
|
||
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
|
||
fmt::Debug::fmt(&**self, f)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T> AsRef<Vec<T>> for Vec<T> {
|
||
fn as_ref(&self) -> &Vec<T> {
|
||
self
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "vec_as_mut", since = "1.5.0")]
|
||
impl<T> AsMut<Vec<T>> for Vec<T> {
|
||
fn as_mut(&mut self) -> &mut Vec<T> {
|
||
self
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T> AsRef<[T]> for Vec<T> {
|
||
fn as_ref(&self) -> &[T] {
|
||
self
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "vec_as_mut", since = "1.5.0")]
|
||
impl<T> AsMut<[T]> for Vec<T> {
|
||
fn as_mut(&mut self) -> &mut [T] {
|
||
self
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<'a, T: Clone> From<&'a [T]> for Vec<T> {
|
||
#[cfg(not(test))]
|
||
fn from(s: &'a [T]) -> Vec<T> {
|
||
s.to_vec()
|
||
}
|
||
#[cfg(test)]
|
||
fn from(s: &'a [T]) -> Vec<T> {
|
||
::slice::to_vec(s)
|
||
}
|
||
}
|
||
|
||
#[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()
|
||
}
|
||
}
|
||
|
||
// note: test pulls in libstd, which causes errors here
|
||
#[cfg(not(test))]
|
||
#[stable(feature = "box_from_vec", since = "1.20.0")]
|
||
impl<T> From<Vec<T>> for Box<[T]> {
|
||
fn from(v: Vec<T>) -> Box<[T]> {
|
||
v.into_boxed_slice()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<'a> From<&'a str> for Vec<u8> {
|
||
fn from(s: &'a str) -> Vec<u8> {
|
||
From::from(s.as_bytes())
|
||
}
|
||
}
|
||
|
||
////////////////////////////////////////////////////////////////////////////////
|
||
// Clone-on-write
|
||
////////////////////////////////////////////////////////////////////////////////
|
||
|
||
#[stable(feature = "cow_from_vec", since = "1.8.0")]
|
||
impl<'a, T: Clone> From<&'a [T]> for Cow<'a, [T]> {
|
||
fn from(s: &'a [T]) -> Cow<'a, [T]> {
|
||
Cow::Borrowed(s)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "cow_from_vec", since = "1.8.0")]
|
||
impl<'a, T: Clone> From<Vec<T>> for Cow<'a, [T]> {
|
||
fn from(v: Vec<T>) -> Cow<'a, [T]> {
|
||
Cow::Owned(v)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "cow_from_vec_ref", since = "1.28.0")]
|
||
impl<'a, T: Clone> From<&'a Vec<T>> for Cow<'a, [T]> {
|
||
fn from(v: &'a Vec<T>) -> Cow<'a, [T]> {
|
||
Cow::Borrowed(v.as_slice())
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<'a, T> FromIterator<T> for Cow<'a, [T]> where T: Clone {
|
||
fn from_iter<I: IntoIterator<Item = T>>(it: I) -> Cow<'a, [T]> {
|
||
Cow::Owned(FromIterator::from_iter(it))
|
||
}
|
||
}
|
||
|
||
////////////////////////////////////////////////////////////////////////////////
|
||
// Iterators
|
||
////////////////////////////////////////////////////////////////////////////////
|
||
|
||
/// An iterator that moves out of a vector.
|
||
///
|
||
/// This `struct` is created by the `into_iter` method on [`Vec`][`Vec`] (provided
|
||
/// by the [`IntoIterator`] trait).
|
||
///
|
||
/// [`Vec`]: struct.Vec.html
|
||
/// [`IntoIterator`]: ../../std/iter/trait.IntoIterator.html
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub struct IntoIter<T> {
|
||
buf: NonNull<T>,
|
||
phantom: PhantomData<T>,
|
||
cap: usize,
|
||
ptr: *const T,
|
||
end: *const T,
|
||
}
|
||
|
||
#[stable(feature = "vec_intoiter_debug", since = "1.13.0")]
|
||
impl<T: fmt::Debug> fmt::Debug for IntoIter<T> {
|
||
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
|
||
f.debug_tuple("IntoIter")
|
||
.field(&self.as_slice())
|
||
.finish()
|
||
}
|
||
}
|
||
|
||
impl<T> IntoIter<T> {
|
||
/// Returns the remaining items of this iterator as a slice.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let vec = vec!['a', 'b', 'c'];
|
||
/// let mut into_iter = vec.into_iter();
|
||
/// assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']);
|
||
/// let _ = into_iter.next().unwrap();
|
||
/// assert_eq!(into_iter.as_slice(), &['b', 'c']);
|
||
/// ```
|
||
#[stable(feature = "vec_into_iter_as_slice", since = "1.15.0")]
|
||
pub fn as_slice(&self) -> &[T] {
|
||
unsafe {
|
||
slice::from_raw_parts(self.ptr, self.len())
|
||
}
|
||
}
|
||
|
||
/// Returns the remaining items of this iterator as a mutable slice.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let vec = vec!['a', 'b', 'c'];
|
||
/// let mut into_iter = vec.into_iter();
|
||
/// assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']);
|
||
/// into_iter.as_mut_slice()[2] = 'z';
|
||
/// assert_eq!(into_iter.next().unwrap(), 'a');
|
||
/// assert_eq!(into_iter.next().unwrap(), 'b');
|
||
/// assert_eq!(into_iter.next().unwrap(), 'z');
|
||
/// ```
|
||
#[stable(feature = "vec_into_iter_as_slice", since = "1.15.0")]
|
||
pub fn as_mut_slice(&mut self) -> &mut [T] {
|
||
unsafe {
|
||
slice::from_raw_parts_mut(self.ptr as *mut T, self.len())
|
||
}
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
unsafe impl<T: Send> Send for IntoIter<T> {}
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
unsafe impl<T: Sync> Sync for IntoIter<T> {}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T> Iterator for IntoIter<T> {
|
||
type Item = T;
|
||
|
||
#[inline]
|
||
fn next(&mut self) -> Option<T> {
|
||
unsafe {
|
||
if self.ptr as *const _ == self.end {
|
||
None
|
||
} else {
|
||
if mem::size_of::<T>() == 0 {
|
||
// purposefully don't use 'ptr.offset' because for
|
||
// vectors with 0-size elements this would return the
|
||
// same pointer.
|
||
self.ptr = arith_offset(self.ptr as *const i8, 1) as *mut T;
|
||
|
||
// Use a non-null pointer value
|
||
// (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);
|
||
|
||
Some(ptr::read(old))
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
#[inline]
|
||
fn size_hint(&self) -> (usize, Option<usize>) {
|
||
let exact = if mem::size_of::<T>() == 0 {
|
||
(self.end as usize).wrapping_sub(self.ptr as usize)
|
||
} else {
|
||
unsafe { self.end.offset_from(self.ptr) as usize }
|
||
};
|
||
(exact, Some(exact))
|
||
}
|
||
|
||
#[inline]
|
||
fn count(self) -> usize {
|
||
self.len()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T> DoubleEndedIterator for IntoIter<T> {
|
||
#[inline]
|
||
fn next_back(&mut self) -> Option<T> {
|
||
unsafe {
|
||
if self.end == self.ptr {
|
||
None
|
||
} else {
|
||
if mem::size_of::<T>() == 0 {
|
||
// See above for why 'ptr.offset' isn't used
|
||
self.end = arith_offset(self.end as *const i8, -1) as *mut T;
|
||
|
||
// Use a non-null pointer value
|
||
// (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(self.end))
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T> ExactSizeIterator for IntoIter<T> {
|
||
fn is_empty(&self) -> bool {
|
||
self.ptr == self.end
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "fused", since = "1.26.0")]
|
||
impl<T> FusedIterator for IntoIter<T> {}
|
||
|
||
#[unstable(feature = "trusted_len", issue = "37572")]
|
||
unsafe impl<T> TrustedLen for IntoIter<T> {}
|
||
|
||
#[stable(feature = "vec_into_iter_clone", since = "1.8.0")]
|
||
impl<T: Clone> Clone for IntoIter<T> {
|
||
fn clone(&self) -> IntoIter<T> {
|
||
self.as_slice().to_owned().into_iter()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
unsafe impl<#[may_dangle] T> Drop for IntoIter<T> {
|
||
fn drop(&mut self) {
|
||
// destroy the remaining elements
|
||
for _x in self.by_ref() {}
|
||
|
||
// RawVec handles deallocation
|
||
let _ = unsafe { RawVec::from_raw_parts(self.buf.as_ptr(), self.cap) };
|
||
}
|
||
}
|
||
|
||
/// A draining iterator for `Vec<T>`.
|
||
///
|
||
/// This `struct` is created by the [`drain`] method on [`Vec`].
|
||
///
|
||
/// [`drain`]: struct.Vec.html#method.drain
|
||
/// [`Vec`]: struct.Vec.html
|
||
#[stable(feature = "drain", since = "1.6.0")]
|
||
pub struct Drain<'a, T: 'a> {
|
||
/// Index of tail to preserve
|
||
tail_start: usize,
|
||
/// Length of tail
|
||
tail_len: usize,
|
||
/// Current remaining range to remove
|
||
iter: slice::Iter<'a, T>,
|
||
vec: NonNull<Vec<T>>,
|
||
}
|
||
|
||
#[stable(feature = "collection_debug", since = "1.17.0")]
|
||
impl<'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 = "drain", since = "1.6.0")]
|
||
impl<'a, T> Iterator for Drain<'a, T> {
|
||
type Item = T;
|
||
|
||
#[inline]
|
||
fn next(&mut self) -> Option<T> {
|
||
self.iter.next().map(|elt| unsafe { ptr::read(elt as *const _) })
|
||
}
|
||
|
||
fn size_hint(&self) -> (usize, Option<usize>) {
|
||
self.iter.size_hint()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "drain", since = "1.6.0")]
|
||
impl<'a, T> DoubleEndedIterator for Drain<'a, T> {
|
||
#[inline]
|
||
fn next_back(&mut self) -> Option<T> {
|
||
self.iter.next_back().map(|elt| unsafe { ptr::read(elt as *const _) })
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "drain", since = "1.6.0")]
|
||
impl<'a, T> Drop for Drain<'a, T> {
|
||
fn drop(&mut self) {
|
||
// exhaust self first
|
||
self.for_each(drop);
|
||
|
||
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;
|
||
if 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 = "drain", since = "1.6.0")]
|
||
impl<'a, T> ExactSizeIterator for Drain<'a, T> {
|
||
fn is_empty(&self) -> bool {
|
||
self.iter.is_empty()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "fused", since = "1.26.0")]
|
||
impl<'a, T> FusedIterator for Drain<'a, T> {}
|
||
|
||
/// A splicing iterator for `Vec`.
|
||
///
|
||
/// This struct is created by the [`splice()`] method on [`Vec`]. See its
|
||
/// documentation for more.
|
||
///
|
||
/// [`splice()`]: struct.Vec.html#method.splice
|
||
/// [`Vec`]: struct.Vec.html
|
||
#[derive(Debug)]
|
||
#[stable(feature = "vec_splice", since = "1.21.0")]
|
||
pub struct Splice<'a, I: Iterator + 'a> {
|
||
drain: Drain<'a, I::Item>,
|
||
replace_with: I,
|
||
}
|
||
|
||
#[stable(feature = "vec_splice", since = "1.21.0")]
|
||
impl<'a, I: Iterator> Iterator for Splice<'a, I> {
|
||
type Item = I::Item;
|
||
|
||
fn next(&mut self) -> Option<Self::Item> {
|
||
self.drain.next()
|
||
}
|
||
|
||
fn size_hint(&self) -> (usize, Option<usize>) {
|
||
self.drain.size_hint()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "vec_splice", since = "1.21.0")]
|
||
impl<'a, I: Iterator> DoubleEndedIterator for Splice<'a, I> {
|
||
fn next_back(&mut self) -> Option<Self::Item> {
|
||
self.drain.next_back()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "vec_splice", since = "1.21.0")]
|
||
impl<'a, I: Iterator> ExactSizeIterator for Splice<'a, I> {}
|
||
|
||
|
||
#[stable(feature = "vec_splice", since = "1.21.0")]
|
||
impl<'a, I: Iterator> Drop for Splice<'a, I> {
|
||
fn drop(&mut self) {
|
||
self.drain.by_ref().for_each(drop);
|
||
|
||
unsafe {
|
||
if self.drain.tail_len == 0 {
|
||
self.drain.vec.as_mut().extend(self.replace_with.by_ref());
|
||
return
|
||
}
|
||
|
||
// First fill the range left by drain().
|
||
if !self.drain.fill(&mut self.replace_with) {
|
||
return
|
||
}
|
||
|
||
// There may be more elements. Use the lower bound as an estimate.
|
||
// FIXME: Is the upper bound a better guess? Or something else?
|
||
let (lower_bound, _upper_bound) = self.replace_with.size_hint();
|
||
if lower_bound > 0 {
|
||
self.drain.move_tail(lower_bound);
|
||
if !self.drain.fill(&mut self.replace_with) {
|
||
return
|
||
}
|
||
}
|
||
|
||
// Collect any remaining elements.
|
||
// This is a zero-length vector which does not allocate if `lower_bound` was exact.
|
||
let mut collected = self.replace_with.by_ref().collect::<Vec<I::Item>>().into_iter();
|
||
// Now we have an exact count.
|
||
if collected.len() > 0 {
|
||
self.drain.move_tail(collected.len());
|
||
let filled = self.drain.fill(&mut collected);
|
||
debug_assert!(filled);
|
||
debug_assert_eq!(collected.len(), 0);
|
||
}
|
||
}
|
||
// Let `Drain::drop` move the tail back if necessary and restore `vec.len`.
|
||
}
|
||
}
|
||
|
||
/// Private helper methods for `Splice::drop`
|
||
impl<'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;
|
||
}
|
||
}
|
||
|
||
/// An iterator produced by calling `drain_filter` on Vec.
|
||
#[unstable(feature = "drain_filter", reason = "recently added", issue = "43244")]
|
||
#[derive(Debug)]
|
||
pub struct DrainFilter<'a, T: 'a, F>
|
||
where F: FnMut(&mut T) -> bool,
|
||
{
|
||
vec: &'a mut Vec<T>,
|
||
idx: usize,
|
||
del: usize,
|
||
old_len: usize,
|
||
pred: F,
|
||
}
|
||
|
||
#[unstable(feature = "drain_filter", reason = "recently added", issue = "43244")]
|
||
impl<'a, T, F> Iterator for DrainFilter<'a, T, F>
|
||
where F: FnMut(&mut T) -> bool,
|
||
{
|
||
type Item = T;
|
||
|
||
fn next(&mut self) -> Option<T> {
|
||
unsafe {
|
||
while self.idx != self.old_len {
|
||
let i = self.idx;
|
||
self.idx += 1;
|
||
let v = slice::from_raw_parts_mut(self.vec.as_mut_ptr(), self.old_len);
|
||
if (self.pred)(&mut v[i]) {
|
||
self.del += 1;
|
||
return Some(ptr::read(&v[i]));
|
||
} else if self.del > 0 {
|
||
let del = self.del;
|
||
let src: *const T = &v[i];
|
||
let dst: *mut T = &mut v[i - del];
|
||
// This is safe because self.vec has length 0
|
||
// thus its elements will not have Drop::drop
|
||
// called on them in the event of a panic.
|
||
ptr::copy_nonoverlapping(src, dst, 1);
|
||
}
|
||
}
|
||
None
|
||
}
|
||
}
|
||
|
||
fn size_hint(&self) -> (usize, Option<usize>) {
|
||
(0, Some(self.old_len - self.idx))
|
||
}
|
||
}
|
||
|
||
#[unstable(feature = "drain_filter", reason = "recently added", issue = "43244")]
|
||
impl<'a, T, F> Drop for DrainFilter<'a, T, F>
|
||
where F: FnMut(&mut T) -> bool,
|
||
{
|
||
fn drop(&mut self) {
|
||
self.for_each(drop);
|
||
unsafe {
|
||
self.vec.set_len(self.old_len - self.del);
|
||
}
|
||
}
|
||
}
|