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// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! A contiguous growable array type with heap-allocated contents, written
//! [`Vec<'bump, T>`].
//!
//! Vectors have `O(1)` indexing, amortized `O(1)` push (to the end) and
//! `O(1)` pop (from the end).
//!
//! This module is a fork of the [`std::vec`] module, that uses a bump allocator.
//!
//! [`std::vec`]: https://doc.rust-lang.org/std/vec/index.html
//!
//! # Examples
//!
//! You can explicitly create a [`Vec<'bump, T>`] with [`new_in`]:
//!
//! ```
//! use bumpalo::{Bump, collections::Vec};
//!
//! let b = Bump::new();
//! let v: Vec<i32> = Vec::new_in(&b);
//! ```
//!
//! ... or by using the [`vec!`] macro:
//!
//! ```
//! use bumpalo::{Bump, collections::Vec};
//!
//! let b = Bump::new();
//!
//! let v: Vec<i32> = bumpalo::vec![in &b];
//!
//! let v = bumpalo::vec![in &b; 1, 2, 3, 4, 5];
//!
//! let v = bumpalo::vec![in &b; 0; 10]; // ten zeroes
//! ```
//!
//! You can [`push`] values onto the end of a vector (which will grow the vector
//! as needed):
//!
//! ```
//! use bumpalo::{Bump, collections::Vec};
//!
//! let b = Bump::new();
//!
//! let mut v = bumpalo::vec![in &b; 1, 2];
//!
//! v.push(3);
//! ```
//!
//! Popping values works in much the same way:
//!
//! ```
//! use bumpalo::{Bump, collections::Vec};
//!
//! let b = Bump::new();
//!
//! let mut v = bumpalo::vec![in &b; 1, 2];
//!
//! assert_eq!(v.pop(), Some(2));
//! ```
//!
//! Vectors also support indexing (through the [`Index`] and [`IndexMut`] traits):
//!
//! ```
//! use bumpalo::{Bump, collections::Vec};
//!
//! let b = Bump::new();
//!
//! let mut v = bumpalo::vec![in &b; 1, 2, 3];
//! assert_eq!(v[2], 3);
//! v[1] += 5;
//! assert_eq!(v, [1, 7, 3]);
//! ```
//!
//! [`Vec<'bump, T>`]: struct.Vec.html
//! [`new_in`]: struct.Vec.html#method.new_in
//! [`push`]: struct.Vec.html#method.push
//! [`Index`]: https://doc.rust-lang.org/std/ops/trait.Index.html
//! [`IndexMut`]: https://doc.rust-lang.org/std/ops/trait.IndexMut.html
//! [`vec!`]: ../../macro.vec.html
use super::raw_vec::RawVec;
use crate::collections::CollectionAllocErr;
use crate::Bump;
use core::borrow::{Borrow, BorrowMut};
use core::cmp::Ordering;
use core::fmt;
use core::hash::{self, Hash};
use core::iter::FusedIterator;
use core::marker::PhantomData;
use core::mem;
use core::ops;
use core::ops::Bound::{Excluded, Included, Unbounded};
use core::ops::{Index, IndexMut, RangeBounds};
use core::ptr;
use core::ptr::NonNull;
use core::slice;
unsafe fn arith_offset<T>(p: *const T, offset: isize) -> *const T {
p.offset(offset)
}
fn partition_dedup_by<T, F>(s: &mut [T], mut same_bucket: F) -> (&mut [T], &mut [T])
where
F: FnMut(&mut T, &mut T) -> bool,
{
// Although we have a mutable reference to `s`, we cannot make
// *arbitrary* changes. The `same_bucket` calls could panic, so we
// must ensure that the slice is in a valid state at all times.
//
// 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 split the slice.
// 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 s[r] against s[w-1], this is not a duplicate, so
// we swap s[r] and s[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 s[r] against s[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 s[r] against s[w-1], this is not a duplicate,
// so swap s[r] and s[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 slice. Split at w.
let len = s.len();
if len <= 1 {
return (s, &mut []);
}
let ptr = s.as_mut_ptr();
let mut next_read: usize = 1;
let mut next_write: usize = 1;
unsafe {
// Avoid bounds checks by using raw pointers.
while next_read < len {
let ptr_read = ptr.add(next_read);
let prev_ptr_write = ptr.add(next_write - 1);
if !same_bucket(&mut *ptr_read, &mut *prev_ptr_write) {
if next_read != next_write {
let ptr_write = prev_ptr_write.offset(1);
mem::swap(&mut *ptr_read, &mut *ptr_write);
}
next_write += 1;
}
next_read += 1;
}
}
s.split_at_mut(next_write)
}
unsafe fn offset_from<T>(p: *const T, origin: *const T) -> isize
where
T: Sized,
{
let pointee_size = mem::size_of::<T>();
assert!(0 < pointee_size && pointee_size <= isize::max_value() as usize);
// This is the same sequence that Clang emits for pointer subtraction.
// It can be neither `nsw` nor `nuw` because the input is treated as
// unsigned but then the output is treated as signed, so neither works.
let d = isize::wrapping_sub(p as _, origin as _);
d / (pointee_size as isize)
}
/// Creates a [`Vec`] containing the arguments.
///
/// `vec!` allows `Vec`s to be defined with the same syntax as array expressions.
/// There are two forms of this macro:
///
/// - Create a [`Vec`] containing a given list of elements:
///
/// ```
/// use bumpalo::Bump;
///
/// let b = Bump::new();
/// let v = bumpalo::vec![in &b; 1, 2, 3];
/// assert_eq!(v, [1, 2, 3]);
/// ```
///
/// - Create a [`Vec`] from a given element and size:
///
/// ```
/// use bumpalo::Bump;
///
/// let b = Bump::new();
/// let v = bumpalo::vec![in &b; 1; 3];
/// assert_eq!(v, [1, 1, 1]);
/// ```
///
/// Note that unlike array expressions, this syntax supports all elements
/// which implement [`Clone`] and the number of elements doesn't have to be
/// a constant.
///
/// This will use `clone` to duplicate an expression, so one should be careful
/// using this with types having a non-standard `Clone` implementation. For
/// example, `bumpalo::vec![in ≎ Rc::new(1); 5]` will create a vector of five references
/// to the same boxed integer value, not five references pointing to independently
/// boxed integers.
///
/// [`Vec`]: collections/vec/struct.Vec.html
/// [`Clone`]: https://doc.rust-lang.org/std/clone/trait.Clone.html
#[macro_export]
macro_rules! vec {
(in $bump:expr; $elem:expr; $n:expr) => {{
let n = $n;
let mut v = $crate::collections::Vec::with_capacity_in(n, $bump);
if n > 0 {
let elem = $elem;
for _ in 0..n - 1 {
v.push(elem.clone());
}
v.push(elem);
}
v
}};
(in $bump:expr) => { $crate::collections::Vec::new_in($bump) };
(in $bump:expr; $($x:expr),*) => {{
let mut v = $crate::collections::Vec::new_in($bump);
$( v.push($x); )*
v
}};
(in $bump:expr; $($x:expr,)*) => (bumpalo::vec![in $bump; $($x),*])
}
/// A contiguous growable array type, written `Vec<'bump, T>` but pronounced 'vector'.
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut vec = Vec::new_in(&b);
/// vec.push(1);
/// vec.push(2);
///
/// assert_eq!(vec.len(), 2);
/// assert_eq!(vec[0], 1);
///
/// assert_eq!(vec.pop(), Some(2));
/// assert_eq!(vec.len(), 1);
///
/// vec[0] = 7;
/// assert_eq!(vec[0], 7);
///
/// vec.extend([1, 2, 3].iter().cloned());
///
/// for x in &vec {
/// println!("{}", x);
/// }
/// assert_eq!(vec, [7, 1, 2, 3]);
/// ```
///
/// The [`vec!`] macro is provided to make initialization more convenient:
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut vec = bumpalo::vec![in &b; 1, 2, 3];
/// vec.push(4);
/// assert_eq!(vec, [1, 2, 3, 4]);
/// ```
///
/// It can also initialize each element of a `Vec<'bump, T>` with a given value.
/// This may be more efficient than performing allocation and initialization
/// in separate steps, especially when initializing a vector of zeros:
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let vec = bumpalo::vec![in &b; 0; 5];
/// assert_eq!(vec, [0, 0, 0, 0, 0]);
///
/// // The following is equivalent, but potentially slower:
/// let mut vec1 = Vec::with_capacity_in(5, &b);
/// vec1.resize(5, 0);
/// ```
///
/// Use a `Vec<'bump, T>` as an efficient stack:
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut stack = Vec::new_in(&b);
///
/// stack.push(1);
/// stack.push(2);
/// stack.push(3);
///
/// while let Some(top) = stack.pop() {
/// // Prints 3, 2, 1
/// println!("{}", top);
/// }
/// ```
///
/// # Indexing
///
/// The `Vec` type allows to access values by index, because it implements the
/// [`Index`] trait. An example will be more explicit:
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let v = bumpalo::vec![in &b; 0, 2, 4, 6];
/// println!("{}", v[1]); // it will display '2'
/// ```
///
/// However be careful: if you try to access an index which isn't in the `Vec`,
/// your software will panic! You cannot do this:
///
/// ```should_panic
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let v = bumpalo::vec![in &b; 0, 2, 4, 6];
/// println!("{}", v[6]); // it will panic!
/// ```
///
/// In conclusion: always check if the index you want to get really exists
/// before doing it.
///
/// # Slicing
///
/// A `Vec` can be mutable. Slices, on the other hand, are read-only objects.
/// To get a slice, use `&`. Example:
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// fn read_slice(slice: &[usize]) {
/// // ...
/// }
///
/// let b = Bump::new();
///
/// let v = bumpalo::vec![in &b; 0, 1];
/// read_slice(&v);
///
/// // ... and that's all!
/// // you can also do it like this:
/// let x : &[usize] = &v;
/// ```
///
/// In Rust, it's more common to pass slices as arguments rather than vectors
/// when you just want to provide a read access. The same goes for [`String`] and
/// [`&str`].
///
/// # Capacity and reallocation
///
/// The capacity of a vector is the amount of space allocated for any future
/// elements that will be added onto the vector. This is not to be confused with
/// the *length* of a vector, which specifies the number of actual elements
/// within the vector. If a vector's length exceeds its capacity, its capacity
/// will automatically be increased, but its elements will have to be
/// reallocated.
///
/// For example, a vector with capacity 10 and length 0 would be an empty vector
/// with space for 10 more elements. Pushing 10 or fewer elements onto the
/// vector will not change its capacity or cause reallocation to occur. However,
/// if the vector's length is increased to 11, it will have to reallocate, which
/// can be slow. For this reason, it is recommended to use [`Vec::with_capacity_in`]
/// whenever possible to specify how big the vector is expected to get.
///
/// # Guarantees
///
/// Due to its incredibly fundamental nature, `Vec` makes a lot of guarantees
/// about its design. This ensures that it's as low-overhead as possible in
/// the general case, and can be correctly manipulated in primitive ways
/// by unsafe code. Note that these guarantees refer to an unqualified `Vec<'bump, T>`.
/// If additional type parameters are added (e.g. to support custom allocators),
/// overriding their defaults may change the behavior.
///
/// Most fundamentally, `Vec` is and always will be a (pointer, capacity, length)
/// triplet. No more, no less. The order of these fields is completely
/// unspecified, and you should use the appropriate methods to modify these.
/// The pointer will never be null, so this type is null-pointer-optimized.
///
/// However, the pointer may not actually point to allocated memory. In particular,
/// if you construct a `Vec` with capacity 0 via [`Vec::new_in`], [`bumpalo::vec![in bump]`][`vec!`],
/// [`Vec::with_capacity_in(0)`][`Vec::with_capacity_in`], or by calling [`shrink_to_fit`]
/// on an empty Vec, it will not allocate memory. Similarly, if you store zero-sized
/// types inside a `Vec`, it will not allocate space for them. *Note that in this case
/// the `Vec` may not report a [`capacity`] of 0*. `Vec` will allocate if and only
/// if <code>[`mem::size_of::<T>`]\() * capacity() > 0</code>. In general, `Vec`'s allocation
/// details are very subtle — if you intend to allocate memory using a `Vec`
/// and use it for something else (either to pass to unsafe code, or to build your
/// own memory-backed collection), be sure to deallocate this memory by using
/// `from_raw_parts` to recover the `Vec` and then dropping it.
///
/// If a `Vec` *has* allocated memory, then the memory it points to is
/// in the [`Bump`] arena used to construct it, and its
/// pointer points to [`len`] initialized, contiguous elements in order (what
/// you would see if you coerced it to a slice), followed by <code>[`capacity`] -
/// [`len`]</code> logically uninitialized, contiguous elements.
///
/// `Vec` will never perform a "small optimization" where elements are actually
/// stored on the stack for two reasons:
///
/// * It would make it more difficult for unsafe code to correctly manipulate
/// a `Vec`. The contents of a `Vec` wouldn't have a stable address if it were
/// only moved, and it would be more difficult to determine if a `Vec` had
/// actually allocated memory.
///
/// * It would penalize the general case, incurring an additional branch
/// on every access.
///
/// `Vec` will never automatically shrink itself, even if completely empty. This
/// ensures no unnecessary allocations or deallocations occur. Emptying a `Vec`
/// and then filling it back up to the same [`len`] should incur no calls to
/// the allocator. If you wish to free up unused memory, use
/// [`shrink_to_fit`][`shrink_to_fit`].
///
/// [`push`] and [`insert`] will never (re)allocate if the reported capacity is
/// sufficient. [`push`] and [`insert`] *will* (re)allocate if
/// <code>[`len`] == [`capacity`]</code>. That is, the reported capacity is completely
/// accurate, and can be relied on. It can even be used to manually free the memory
/// allocated by a `Vec` if desired. Bulk insertion methods *may* reallocate, even
/// when not necessary.
///
/// `Vec` does not guarantee any particular growth strategy when reallocating
/// when full, nor when [`reserve`] is called. The current strategy is basic
/// and it may prove desirable to use a non-constant growth factor. Whatever
/// strategy is used will of course guarantee `O(1)` amortized [`push`].
///
/// `bumpalo::vec![in bump; x; n]`, `bumpalo::vec![in bump; a, b, c, d]`, and
/// [`Vec::with_capacity_in(n)`][`Vec::with_capacity_in`], will all produce a
/// `Vec` with exactly the requested capacity. If <code>[`len`] == [`capacity`]</code>, (as
/// is the case for the [`vec!`] macro), then a `Vec<'bump, T>` can be converted
/// to and from a [`Box<[T]>`][owned slice] without reallocating or moving the
/// elements.
///
/// `Vec` will not specifically overwrite any data that is removed from it,
/// but also won't specifically preserve it. Its uninitialized memory is
/// scratch space that it may use however it wants. It will generally just do
/// whatever is most efficient or otherwise easy to implement. Do not rely on
/// removed data to be erased for security purposes. Even if you drop a `Vec`, its
/// buffer may simply be reused by another `Vec`. Even if you zero a `Vec`'s memory
/// first, that may not actually happen because the optimizer does not consider
/// this a side-effect that must be preserved. There is one case which we will
/// not break, however: using `unsafe` code to write to the excess capacity,
/// and then increasing the length to match, is always valid.
///
/// `Vec` does not currently guarantee the order in which elements are dropped.
/// The order has changed in the past and may change again.
///
/// [`vec!`]: ../../macro.vec.html
/// [`Index`]: https://doc.rust-lang.org/std/ops/trait.Index.html
/// [`String`]: ../string/struct.String.html
/// [`&str`]: https://doc.rust-lang.org/std/primitive.str.html
/// [`Vec::with_capacity_in`]: struct.Vec.html#method.with_capacity_in
/// [`Vec::new_in`]: struct.Vec.html#method.new_in
/// [`shrink_to_fit`]: struct.Vec.html#method.shrink_to_fit
/// [`capacity`]: struct.Vec.html#method.capacity
/// [`mem::size_of::<T>`]: https://doc.rust-lang.org/std/mem/fn.size_of.html
/// [`len`]: struct.Vec.html#method.len
/// [`push`]: struct.Vec.html#method.push
/// [`insert`]: struct.Vec.html#method.insert
/// [`reserve`]: struct.Vec.html#method.reserve
/// [owned slice]: https://doc.rust-lang.org/std/boxed/struct.Box.html
pub struct Vec<'bump, T: 'bump> {
buf: RawVec<'bump, T>,
len: usize,
}
////////////////////////////////////////////////////////////////////////////////
// Inherent methods
////////////////////////////////////////////////////////////////////////////////
impl<'bump, T: 'bump> Vec<'bump, T> {
/// Constructs a new, empty `Vec<'bump, T>`.
///
/// The vector will not allocate until elements are pushed onto it.
///
/// # Examples
///
/// ```
/// # #![allow(unused_mut)]
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
/// let mut vec: Vec<i32> = Vec::new_in(&b);
/// ```
#[inline]
pub fn new_in(bump: &'bump Bump) -> Vec<'bump, T> {
Vec {
buf: RawVec::new_in(bump),
len: 0,
}
}
/// Constructs a new, empty `Vec<'bump, T>` with the specified capacity.
///
/// The vector will be able to hold exactly `capacity` elements without
/// reallocating. If `capacity` is 0, the vector will not allocate.
///
/// It is important to note that although the returned vector has the
/// *capacity* specified, the vector will have a zero *length*. For an
/// explanation of the difference between length and capacity, see
/// *[Capacity and reallocation]*.
///
/// [Capacity and reallocation]: #capacity-and-reallocation
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut vec = Vec::with_capacity_in(10, &b);
///
/// // The vector contains no items, even though it has capacity for more
/// assert_eq!(vec.len(), 0);
///
/// // These are all done without reallocating...
/// for i in 0..10 {
/// vec.push(i);
/// }
///
/// // ...but this may make the vector reallocate
/// vec.push(11);
/// ```
#[inline]
pub fn with_capacity_in(capacity: usize, bump: &'bump Bump) -> Vec<'bump, T> {
Vec {
buf: RawVec::with_capacity_in(capacity, bump),
len: 0,
}
}
/// Construct a new `Vec` from the given iterator's items.
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
/// use std::iter;
///
/// let b = Bump::new();
/// let v = Vec::from_iter_in(iter::repeat(7).take(3), &b);
/// assert_eq!(v, [7, 7, 7]);
/// ```
pub fn from_iter_in<I: IntoIterator<Item = T>>(iter: I, bump: &'bump Bump) -> Vec<'bump, T> {
let mut v = Vec::new_in(bump);
v.extend(iter);
v
}
/// Creates a `Vec<'bump, T>` directly from the raw components of another vector.
///
/// # Safety
///
/// This is highly unsafe, due to the number of invariants that aren't
/// checked:
///
/// * `ptr` needs to have been previously allocated via [`String`]/`Vec<'bump, T>`
/// (at least, it's highly likely to be incorrect if it wasn't).
/// * `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<'bump, 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`]: ../string/struct.String.html
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// use std::ptr;
/// use std::mem;
///
/// let b = Bump::new();
///
/// let mut v = bumpalo::vec![in &b; 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_in(p, len, cap, &b);
/// assert_eq!(rebuilt, [4, 5, 6]);
/// }
/// ```
pub unsafe fn from_raw_parts_in(
ptr: *mut T,
length: usize,
capacity: usize,
bump: &'bump Bump,
) -> Vec<'bump, T> {
Vec {
buf: RawVec::from_raw_parts_in(ptr, capacity, bump),
len: length,
}
}
/// Returns a shared reference to the allocator backing this `Vec`.
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// // uses the same allocator as the provided `Vec`
/// fn add_strings<'bump>(vec: &mut Vec<'bump, &'bump str>) {
/// for string in ["foo", "bar", "baz"] {
/// vec.push(vec.bump().alloc_str(string));
/// }
/// }
/// ```
#[inline]
#[must_use]
pub fn bump(&self) -> &'bump Bump {
self.buf.bump()
}
/// Returns the number of elements the vector can hold without
/// reallocating.
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
/// let vec: Vec<i32> = Vec::with_capacity_in(10, &b);
/// assert_eq!(vec.capacity(), 10);
/// ```
#[inline]
pub fn capacity(&self) -> usize {
self.buf.cap()
}
/// Reserves capacity for at least `additional` more elements to be inserted
/// in the given `Vec<'bump, 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
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
/// let mut vec = bumpalo::vec![in &b; 1];
/// vec.reserve(10);
/// assert!(vec.capacity() >= 11);
/// ```
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<'bump, 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
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
/// let mut vec = bumpalo::vec![in &b; 1];
/// vec.reserve_exact(10);
/// assert!(vec.capacity() >= 11);
/// ```
pub fn reserve_exact(&mut self, additional: usize) {
self.buf.reserve_exact(self.len, additional);
}
/// Attempts to reserve capacity for at least `additional` more elements to be inserted
/// in the given `Vec<'bump, T>`. The collection may reserve more space to avoid
/// frequent reallocations. After calling `try_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
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
/// let mut vec = bumpalo::vec![in &b; 1];
/// vec.try_reserve(10).unwrap();
/// assert!(vec.capacity() >= 11);
/// ```
pub fn try_reserve(&mut self, additional: usize) -> Result<(), CollectionAllocErr> {
self.buf.try_reserve(self.len, additional)
}
/// Attempts to reserve the minimum capacity for exactly `additional` more elements to
/// be inserted in the given `Vec<'bump, T>`. After calling `try_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 `try_reserve` if future insertions are expected.
///
/// # Panics
///
/// Panics if the new capacity overflows `usize`.
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
/// let mut vec = bumpalo::vec![in &b; 1];
/// vec.try_reserve_exact(10).unwrap();
/// assert!(vec.capacity() >= 11);
/// ```
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
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut vec = Vec::with_capacity_in(10, &b);
/// vec.extend([1, 2, 3].iter().cloned());
/// assert_eq!(vec.capacity(), 10);
/// vec.shrink_to_fit();
/// assert!(vec.capacity() >= 3);
/// ```
pub fn shrink_to_fit(&mut self) {
if self.capacity() != self.len {
self.buf.shrink_to_fit(self.len);
}
}
/// Converts the vector into `&'bump [T]`.
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
/// let v = bumpalo::vec![in &b; 1, 2, 3];
///
/// let slice = v.into_bump_slice();
/// assert_eq!(slice, [1, 2, 3]);
/// ```
pub fn into_bump_slice(self) -> &'bump [T] {
unsafe {
let ptr = self.as_ptr();
let len = self.len();
mem::forget(self);
slice::from_raw_parts(ptr, len)
}
}
/// Converts the vector into `&'bump mut [T]`.
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
/// let v = bumpalo::vec![in &b; 1, 2, 3];
///
/// let mut slice = v.into_bump_slice_mut();
///
/// slice[0] = 3;
/// slice[2] = 1;
///
/// assert_eq!(slice, [3, 2, 1]);
/// ```
pub fn into_bump_slice_mut(mut self) -> &'bump mut [T] {
let ptr = self.as_mut_ptr();
let len = self.len();
mem::forget(self);
unsafe { slice::from_raw_parts_mut(ptr, len) }
}
/// 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:
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut vec = bumpalo::vec![in &b; 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:
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut vec = bumpalo::vec![in &b; 1, 2, 3];
/// vec.truncate(8);
/// assert_eq!(vec, [1, 2, 3]);
/// ```
///
/// Truncating when `len == 0` is equivalent to calling the [`clear`]
/// method.
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut vec = bumpalo::vec![in &b; 1, 2, 3];
/// vec.truncate(0);
/// assert_eq!(vec, []);
/// ```
///
/// [`clear`]: #method.clear
/// [`drain`]: #method.drain
pub fn truncate(&mut self, len: usize) {
let current_len = self.len;
unsafe {
let mut ptr = self.as_mut_ptr().add(self.len);
// Set the final length at the end, keeping in mind that
// dropping an element might panic. Works around a missed
// optimization, as seen in the following issue:
// https://github.com/rust-lang/rust/issues/51802
let mut local_len = SetLenOnDrop::new(&mut self.len);
// drop any extra elements
for _ in len..current_len {
local_len.decrement_len(1);
ptr = ptr.offset(-1);
ptr::drop_in_place(ptr);
}
}
}
/// Extracts a slice containing the entire vector.
///
/// Equivalent to `&s[..]`.
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
/// use std::io::{self, Write};
///
/// let b = Bump::new();
///
/// let buffer = bumpalo::vec![in &b; 1, 2, 3, 5, 8];
/// io::sink().write(buffer.as_slice()).unwrap();
/// ```
#[inline]
pub fn as_slice(&self) -> &[T] {
self
}
/// Extracts a mutable slice of the entire vector.
///
/// Equivalent to `&mut s[..]`.
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
/// use std::io::{self, Read};
///
/// let b = Bump::new();
/// let mut buffer = bumpalo::vec![in &b; 0; 3];
/// io::repeat(0b101).read_exact(buffer.as_mut_slice()).unwrap();
/// ```
#[inline]
pub fn as_mut_slice(&mut self) -> &mut [T] {
self
}
/// Returns a raw pointer to the vector's buffer, or a dangling raw pointer
/// valid for zero sized reads if the vector didn't allocate.
///
/// The caller must ensure that the vector outlives the pointer this
/// function returns, or else it will end up pointing to garbage.
/// Modifying the vector may cause its buffer to be reallocated,
/// which would also make any pointers to it invalid.
///
/// The caller must also ensure that the memory the pointer (non-transitively) points to
/// is never written to (except inside an `UnsafeCell`) using this pointer or any pointer
/// derived from it. If you need to mutate the contents of the slice, use [`as_mut_ptr`].
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let bump = Bump::new();
///
/// let x = bumpalo::vec![in ≎ 1, 2, 4];
/// let x_ptr = x.as_ptr();
///
/// unsafe {
/// for i in 0..x.len() {
/// assert_eq!(*x_ptr.add(i), 1 << i);
/// }
/// }
/// ```
///
/// [`as_mut_ptr`]: Vec::as_mut_ptr
#[inline]
pub fn as_ptr(&self) -> *const T {
// We shadow the slice method of the same name to avoid going through
// `deref`, which creates an intermediate reference.
let ptr = self.buf.ptr();
unsafe {
if ptr.is_null() {
core::hint::unreachable_unchecked();
}
}
ptr
}
/// Returns an unsafe mutable pointer to the vector's buffer, or a dangling
/// raw pointer valid for zero sized reads if the vector didn't allocate.
///
/// The caller must ensure that the vector outlives the pointer this
/// function returns, or else it will end up pointing to garbage.
/// Modifying the vector may cause its buffer to be reallocated,
/// which would also make any pointers to it invalid.
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let bump = Bump::new();
///
/// // Allocate vector big enough for 4 elements.
/// let size = 4;
/// let mut x: Vec<i32> = Vec::with_capacity_in(size, &bump);
/// let x_ptr = x.as_mut_ptr();
///
/// // Initialize elements via raw pointer writes, then set length.
/// unsafe {
/// for i in 0..size {
/// x_ptr.add(i).write(i as i32);
/// }
/// x.set_len(size);
/// }
/// assert_eq!(&*x, &[0, 1, 2, 3]);
/// ```
#[inline]
pub fn as_mut_ptr(&mut self) -> *mut T {
// We shadow the slice method of the same name to avoid going through
// `deref_mut`, which creates an intermediate reference.
let ptr = self.buf.ptr();
unsafe {
if ptr.is_null() {
core::hint::unreachable_unchecked();
}
}
ptr
}
/// 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.
///
/// # Safety
///
/// - `new_len` must be less than or equal to [`capacity()`].
/// - The elements at `old_len..new_len` must be initialized.
///
/// [`capacity()`]: struct.Vec.html#method.capacity
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// use std::ptr;
///
/// let b = Bump::new();
///
/// let mut vec = bumpalo::vec![in &b; '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:
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut vec = bumpalo::vec![in &b;
/// bumpalo::vec![in &b; 1, 0, 0],
/// bumpalo::vec![in &b; 0, 1, 0],
/// bumpalo::vec![in &b; 0, 0, 1]];
/// unsafe {
/// vec.set_len(0);
/// }
/// ```
///
/// In this example, the vector gets expanded from zero to four items
/// but we directly initialize uninitialized memory:
///
// TODO: rely upon `spare_capacity_mut`
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let len = 4;
/// let b = Bump::new();
///
/// let mut vec: Vec<u8> = Vec::with_capacity_in(len, &b);
///
/// for i in 0..len {
/// // SAFETY: we initialize memory via `pointer::write`
/// unsafe { vec.as_mut_ptr().add(i).write(b'a') }
/// }
///
/// unsafe {
/// vec.set_len(len);
/// }
///
/// assert_eq!(b"aaaa", &*vec);
/// ```
#[inline]
pub unsafe fn set_len(&mut self, new_len: usize) {
self.len = new_len;
}
/// Removes an element from the vector and returns it.
///
/// The removed element is replaced by the last element of the vector.
///
/// This does not preserve ordering, but is O(1).
///
/// # Panics
///
/// Panics if `index` is out of bounds.
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut v = bumpalo::vec![in &b; "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]
pub fn swap_remove(&mut self, index: usize) -> T {
unsafe {
// We replace self[index] with the last element. Note that if the
// bounds check on hole succeeds there must be a last element (which
// can be self[index] itself).
let hole: *mut T = &mut self[index];
let last = ptr::read(self.get_unchecked(self.len - 1));
self.len -= 1;
ptr::replace(hole, last)
}
}
/// Inserts an element at position `index` within the vector, shifting all
/// elements after it to the right.
///
/// # Panics
///
/// Panics if `index > len`.
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut vec = bumpalo::vec![in &b; 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]);
/// ```
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.reserve(1);
}
unsafe {
// infallible
// The spot to put the new value
{
let p = self.as_mut_ptr().add(index);
// Shift everything over to make space. (Duplicating the
// `index`th element into two consecutive places.)
ptr::copy(p, p.offset(1), len - index);
// Write it in, overwriting the first copy of the `index`th
// element.
ptr::write(p, element);
}
self.set_len(len + 1);
}
}
/// Removes and returns the element at position `index` within the vector,
/// shifting all elements after it to the left.
///
/// # Panics
///
/// Panics if `index` is out of bounds.
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut v = bumpalo::vec![in &b; 1, 2, 3];
/// assert_eq!(v.remove(1), 2);
/// assert_eq!(v, [1, 3]);
/// ```
pub fn remove(&mut self, index: usize) -> T {
let len = self.len();
assert!(index < len);
unsafe {
// infallible
let ret;
{
// the place we are taking from.
let ptr = self.as_mut_ptr().add(index);
// copy it out, unsafely having a copy of the value on
// the stack and in the vector at the same time.
ret = ptr::read(ptr);
// Shift everything down to fill in that spot.
ptr::copy(ptr.offset(1), ptr, len - index - 1);
}
self.set_len(len - 1);
ret
}
}
/// Retains only the elements specified by the predicate.
///
/// In other words, remove all elements `e` such that `f(&e)` returns `false`.
/// This method operates in place and preserves the order of the retained
/// elements.
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut vec = bumpalo::vec![in &b; 1, 2, 3, 4];
/// vec.retain(|&x| x % 2 == 0);
/// assert_eq!(vec, [2, 4]);
/// ```
pub fn retain<F>(&mut self, mut f: F)
where
F: FnMut(&T) -> bool,
{
self.drain_filter(|x| !f(x));
}
/// Creates an iterator that removes the elements in the vector
/// for which the predicate returns `true` and yields the removed items.
///
/// # Examples
///
/// ```
/// use bumpalo::Bump;
/// use bumpalo::collections::{CollectIn, Vec};
///
/// let b = Bump::new();
///
/// let mut numbers = bumpalo::vec![in &b; 1, 2, 3, 4, 5];
///
/// let evens: Vec<_> = numbers.drain_filter(|x| *x % 2 == 0).collect_in(&b);
///
/// assert_eq!(numbers, &[1, 3, 5]);
/// assert_eq!(evens, &[2, 4]);
/// ```
pub fn drain_filter<'a, F>(&'a mut self, filter: F) -> DrainFilter<'a, 'bump, 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,
}
}
/// 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
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut vec = bumpalo::vec![in &b; 10, 20, 21, 30, 20];
///
/// vec.dedup_by_key(|i| *i / 10);
///
/// assert_eq!(vec, [10, 20, 30, 20]);
/// ```
#[inline]
pub fn dedup_by_key<F, K>(&mut self, mut key: F)
where
F: FnMut(&mut T) -> K,
K: PartialEq,
{
self.dedup_by(|a, b| key(a) == key(b))
}
/// Removes all but the first of consecutive elements in the vector satisfying a given equality
/// relation.
///
/// The `same_bucket` function is passed references to two elements from the vector and
/// must determine if the elements compare equal. The elements are passed in opposite order
/// from their order in the slice, so if `same_bucket(a, b)` returns `true`, `a` is removed.
///
/// If the vector is sorted, this removes all duplicates.
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut vec = bumpalo::vec![in &b; "foo", "bar", "Bar", "baz", "bar"];
///
/// vec.dedup_by(|a, b| a.eq_ignore_ascii_case(b));
///
/// assert_eq!(vec, ["foo", "bar", "baz", "bar"]);
/// ```
pub fn dedup_by<F>(&mut self, same_bucket: F)
where
F: FnMut(&mut T, &mut T) -> bool,
{
let len = {
let (dedup, _) = partition_dedup_by(self.as_mut_slice(), same_bucket);
dedup.len()
};
self.truncate(len);
}
/// Appends an element to the back of a vector.
///
/// # Panics
///
/// Panics if the number of elements in the vector overflows a `usize`.
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut vec = bumpalo::vec![in &b; 1, 2];
/// vec.push(3);
/// assert_eq!(vec, [1, 2, 3]);
/// ```
#[inline]
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.reserve(1);
}
unsafe {
let end = self.buf.ptr().add(self.len);
ptr::write(end, value);
self.len += 1;
}
}
/// Removes the last element from a vector and returns it, or [`None`] if it
/// is empty.
///
/// [`None`]: https://doc.rust-lang.org/std/option/enum.Option.html#variant.None
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut vec = bumpalo::vec![in &b; 1, 2, 3];
/// assert_eq!(vec.pop(), Some(3));
/// assert_eq!(vec, [1, 2]);
/// ```
#[inline]
pub fn pop(&mut self) -> Option<T> {
if self.len == 0 {
None
} else {
unsafe {
self.len -= 1;
Some(ptr::read(self.as_ptr().add(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
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut vec = bumpalo::vec![in &b; 1, 2, 3];
/// let mut vec2 = bumpalo::vec![in &b; 4, 5, 6];
/// vec.append(&mut vec2);
/// assert_eq!(vec, [1, 2, 3, 4, 5, 6]);
/// assert_eq!(vec2, []);
/// ```
#[inline]
pub fn append(&mut self, other: &mut Self) {
unsafe {
self.append_elements(other.as_slice() as _);
other.set_len(0);
}
}
/// Appends elements to `Self` from other buffer.
#[inline]
unsafe fn append_elements(&mut self, other: *const [T]) {
let count = (*other).len();
self.reserve(count);
let len = self.len();
ptr::copy_nonoverlapping(other as *const T, self.as_mut_ptr().add(len), count);
self.len += count;
}
/// Creates a draining iterator that removes the specified range in the vector
/// and yields the removed items.
///
/// Note 1: The element range is removed even if the iterator is only
/// partially consumed or not consumed at all.
///
/// Note 2: It is unspecified how many elements are removed from the vector
/// if the `Drain` value is leaked.
///
/// # Panics
///
/// Panics if the starting point is greater than the end point or if
/// the end point is greater than the length of the vector.
///
/// # Examples
///
/// ```
/// use bumpalo::Bump;
/// use bumpalo::collections::{CollectIn, Vec};
///
/// let b = Bump::new();
///
/// let mut v = bumpalo::vec![in &b; 1, 2, 3];
///
/// let u: Vec<_> = v.drain(1..).collect_in(&b);
///
/// assert_eq!(v, &[1]);
/// assert_eq!(u, &[2, 3]);
///
/// // A full range clears the vector
/// v.drain(..);
/// assert_eq!(v, &[]);
/// ```
pub fn drain<R>(&mut self, range: R) -> Drain<T>
where
R: RangeBounds<usize>,
{
// Memory safety
//
// When the Drain is first created, it shortens the length of
// the source vector to make sure no uninitialized or moved-from elements
// are accessible at all if the Drain's destructor never gets to run.
//
// Drain will ptr::read out the values to remove.
// When finished, remaining tail of the vec is copied back to cover
// the hole, and the vector length is restored to the new length.
//
let len = self.len();
let start = match range.start_bound() {
Included(&n) => n,
Excluded(&n) => n + 1,
Unbounded => 0,
};
let end = match range.end_bound() {
Included(&n) => n + 1,
Excluded(&n) => n,
Unbounded => len,
};
assert!(start <= end);
assert!(end <= len);
unsafe {
// set self.vec length's to start, to be safe in case Drain is leaked
self.set_len(start);
// Use the borrow in the IterMut to indicate borrowing behavior of the
// whole Drain iterator (like &mut T).
let range_slice = slice::from_raw_parts_mut(self.as_mut_ptr().add(start), end - start);
Drain {
tail_start: end,
tail_len: len - end,
iter: range_slice.iter(),
vec: NonNull::from(self),
}
}
}
/// Clears the vector, removing all values.
///
/// Note that this method has no effect on the allocated capacity
/// of the vector.
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut v = bumpalo::vec![in &b; 1, 2, 3];
///
/// v.clear();
///
/// assert!(v.is_empty());
/// ```
#[inline]
pub fn clear(&mut self) {
self.truncate(0)
}
/// Returns the number of elements in the vector, also referred to
/// as its 'length'.
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let a = bumpalo::vec![in &b; 1, 2, 3];
/// assert_eq!(a.len(), 3);
/// ```
#[inline]
pub fn len(&self) -> usize {
self.len
}
/// Returns `true` if the vector contains no elements.
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut v = Vec::new_in(&b);
/// assert!(v.is_empty());
///
/// v.push(1);
/// assert!(!v.is_empty());
/// ```
pub fn is_empty(&self) -> bool {
self.len() == 0
}
/// Splits the collection into two at the given index.
///
/// Returns a newly allocated vector. `self` contains elements `[0, at)`,
/// and the returned vector contains elements `[at, len)`.
///
/// Note that the capacity of `self` does not change.
///
/// # Panics
///
/// Panics if `at > len`.
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut vec = bumpalo::vec![in &b; 1, 2, 3];
/// let vec2 = vec.split_off(1);
/// assert_eq!(vec, [1]);
/// assert_eq!(vec2, [2, 3]);
/// ```
#[inline]
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_in(other_len, self.buf.bump());
// Unsafely `set_len` and copy items to `other`.
unsafe {
self.set_len(at);
other.set_len(other_len);
ptr::copy_nonoverlapping(self.as_ptr().add(at), other.as_mut_ptr(), other.len());
}
other
}
}
#[cfg(feature = "boxed")]
impl<'bump, T> Vec<'bump, T> {
/// Converts the vector into [`Box<[T]>`][owned slice].
///
/// Note that this will drop any excess capacity.
///
/// [owned slice]: ../../boxed/struct.Box.html
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec, vec};
///
/// let b = Bump::new();
///
/// let v = vec![in &b; 1, 2, 3];
///
/// let slice = v.into_boxed_slice();
/// ```
pub fn into_boxed_slice(mut self) -> crate::boxed::Box<'bump, [T]> {
use crate::boxed::Box;
// Unlike `alloc::vec::Vec` shrinking here isn't necessary as `bumpalo::boxed::Box` doesn't own memory.
unsafe {
let slice = slice::from_raw_parts_mut(self.as_mut_ptr(), self.len);
let output: Box<'bump, [T]> = Box::from_raw(slice);
mem::forget(self);
output
}
}
}
impl<'bump, T: 'bump + Clone> Vec<'bump, 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
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut vec = bumpalo::vec![in &b; "hello"];
/// vec.resize(3, "world");
/// assert_eq!(vec, ["hello", "world", "world"]);
///
/// let mut vec = bumpalo::vec![in &b; 1, 2, 3, 4];
/// vec.resize(2, 0);
/// assert_eq!(vec, [1, 2]);
/// ```
///
/// [`Clone`]: https://doc.rust-lang.org/std/clone/trait.Clone.html
/// [`Default`]: https://doc.rust-lang.org/std/default/trait.Default.html
/// [`resize_with`]: #method.resize_with
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
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut vec = bumpalo::vec![in &b; 1];
/// vec.extend_from_slice(&[2, 3, 4]);
/// assert_eq!(vec, [1, 2, 3, 4]);
/// ```
///
/// [`extend`]: #method.extend
pub fn extend_from_slice(&mut self, other: &[T]) {
self.extend(other.iter().cloned())
}
}
// 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
}
}
impl<'bump, T: 'bump> Vec<'bump, T> {
/// Extend the vector by `n` values, using the given generator.
fn extend_with<E: ExtendWith<T>>(&mut self, n: usize, mut value: E) {
self.reserve(n);
unsafe {
let mut ptr = self.as_mut_ptr().add(self.len());
// Use SetLenOnDrop to work around bug where compiler
// may not realize the store through `ptr` through self.set_len()
// don't alias.
let mut local_len = SetLenOnDrop::new(&mut self.len);
// Write all elements except the last one
for _ in 1..n {
ptr::write(ptr, value.next());
ptr = ptr.offset(1);
// Increment the length in every step in case next() panics
local_len.increment_len(1);
}
if n > 0 {
// We can write the last element directly without cloning needlessly
ptr::write(ptr, value.last());
local_len.increment_len(1);
}
// len set by scope guard
}
}
}
// Set the length of the vec when the `SetLenOnDrop` value goes out of scope.
//
// The idea is: The length field in SetLenOnDrop is a local variable
// that the optimizer will see does not alias with any stores through the Vec's data
// pointer. This is a workaround for alias analysis issue #32155
struct SetLenOnDrop<'a> {
len: &'a mut usize,
local_len: usize,
}
impl<'a> SetLenOnDrop<'a> {
#[inline]
fn new(len: &'a mut usize) -> Self {
SetLenOnDrop {
local_len: *len,
len,
}
}
#[inline]
fn increment_len(&mut self, increment: usize) {
self.local_len += increment;
}
#[inline]
fn decrement_len(&mut self, decrement: usize) {
self.local_len -= decrement;
}
}
impl<'a> Drop for SetLenOnDrop<'a> {
#[inline]
fn drop(&mut self) {
*self.len = self.local_len;
}
}
impl<'bump, T: 'bump + PartialEq> Vec<'bump, T> {
/// Removes consecutive repeated elements in the vector according to the
/// [`PartialEq`] trait implementation.
///
/// If the vector is sorted, this removes all duplicates.
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut vec = bumpalo::vec![in &b; 1, 2, 2, 3, 2];
///
/// vec.dedup();
///
/// assert_eq!(vec, [1, 2, 3, 2]);
/// ```
#[inline]
pub fn dedup(&mut self) {
self.dedup_by(|a, b| a == b)
}
}
////////////////////////////////////////////////////////////////////////////////
// Common trait implementations for Vec
////////////////////////////////////////////////////////////////////////////////
impl<'bump, T: 'bump + Clone> Clone for Vec<'bump, T> {
#[cfg(not(test))]
fn clone(&self) -> Vec<'bump, T> {
let mut v = Vec::with_capacity_in(self.len(), self.buf.bump());
v.extend(self.iter().cloned());
v
}
// 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<'bump, T> {
let mut v = Vec::new_in(self.buf.bump());
v.extend(self.iter().cloned());
v
}
}
impl<'bump, T: 'bump + Hash> Hash for Vec<'bump, T> {
#[inline]
fn hash<H: hash::Hasher>(&self, state: &mut H) {
Hash::hash(&**self, state)
}
}
impl<'bump, T, I> Index<I> for Vec<'bump, T>
where
I: ::core::slice::SliceIndex<[T]>,
{
type Output = I::Output;
#[inline]
fn index(&self, index: I) -> &Self::Output {
Index::index(&**self, index)
}
}
impl<'bump, T, I> IndexMut<I> for Vec<'bump, T>
where
I: ::core::slice::SliceIndex<[T]>,
{
#[inline]
fn index_mut(&mut self, index: I) -> &mut Self::Output {
IndexMut::index_mut(&mut **self, index)
}
}
impl<'bump, T: 'bump> ops::Deref for Vec<'bump, 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)
}
}
}
impl<'bump, T: 'bump> ops::DerefMut for Vec<'bump, 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)
}
}
}
impl<'bump, T: 'bump> IntoIterator for Vec<'bump, T> {
type Item = T;
type IntoIter = IntoIter<'bump, 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
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let v = bumpalo::vec![in &b; "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<'bump, 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.add(self.len()) as *const T
};
mem::forget(self);
IntoIter {
phantom: PhantomData,
ptr: begin,
end,
}
}
}
}
impl<'a, 'bump, T> IntoIterator for &'a Vec<'bump, T> {
type Item = &'a T;
type IntoIter = slice::Iter<'a, T>;
fn into_iter(self) -> slice::Iter<'a, T> {
self.iter()
}
}
impl<'a, 'bump, T> IntoIterator for &'a mut Vec<'bump, T> {
type Item = &'a mut T;
type IntoIter = slice::IterMut<'a, T>;
fn into_iter(self) -> slice::IterMut<'a, T> {
self.iter_mut()
}
}
impl<'bump, T: 'bump> Extend<T> for Vec<'bump, T> {
#[inline]
fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I) {
let iter = iter.into_iter();
self.reserve(iter.size_hint().0);
for t in iter {
self.push(t);
}
}
}
impl<'bump, T: 'bump> Vec<'bump, T> {
/// 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
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let mut v = bumpalo::vec![in &b; 1, 2, 3];
/// let new = [7, 8];
/// let u: Vec<_> = Vec::from_iter_in(v.splice(..2, new.iter().cloned()), &b);
/// assert_eq!(v, &[7, 8, 3]);
/// assert_eq!(u, &[1, 2]);
/// ```
#[inline]
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(),
}
}
}
/// 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`]: https://doc.rust-lang.org/std/primitive.slice.html#method.copy_from_slice
impl<'a, 'bump, T: 'a + Copy> Extend<&'a T> for Vec<'bump, T> {
fn extend<I: IntoIterator<Item = &'a T>>(&mut self, iter: I) {
self.extend(iter.into_iter().cloned())
}
}
macro_rules! __impl_slice_eq1 {
($Lhs: ty, $Rhs: ty) => {
__impl_slice_eq1! { $Lhs, $Rhs, Sized }
};
($Lhs: ty, $Rhs: ty, $Bound: ident) => {
impl<'a, 'b, A: $Bound, B> PartialEq<$Rhs> for $Lhs
where
A: PartialEq<B>,
{
#[inline]
fn eq(&self, other: &$Rhs) -> bool {
self[..] == other[..]
}
}
};
}
__impl_slice_eq1! { Vec<'a, A>, Vec<'b, B> }
__impl_slice_eq1! { Vec<'a, A>, &'b [B] }
__impl_slice_eq1! { Vec<'a, A>, &'b mut [B] }
// __impl_slice_eq1! { Cow<'a, [A]>, Vec<'b, B>, Clone }
macro_rules! __impl_slice_eq1_array {
($Lhs: ty, $Rhs: ty) => {
impl<'a, 'b, A, B, const N: usize> PartialEq<$Rhs> for $Lhs
where
A: PartialEq<B>,
{
#[inline]
fn eq(&self, other: &$Rhs) -> bool {
self[..] == other[..]
}
}
};
}
__impl_slice_eq1_array! { Vec<'a, A>, [B; N] }
__impl_slice_eq1_array! { Vec<'a, A>, &'b [B; N] }
__impl_slice_eq1_array! { Vec<'a, A>, &'b mut [B; N] }
/// Implements comparison of vectors, lexicographically.
impl<'bump, T: 'bump + PartialOrd> PartialOrd for Vec<'bump, T> {
#[inline]
fn partial_cmp(&self, other: &Vec<'bump, T>) -> Option<Ordering> {
PartialOrd::partial_cmp(&**self, &**other)
}
}
impl<'bump, T: 'bump + Eq> Eq for Vec<'bump, T> {}
/// Implements ordering of vectors, lexicographically.
impl<'bump, T: 'bump + Ord> Ord for Vec<'bump, T> {
#[inline]
fn cmp(&self, other: &Vec<'bump, T>) -> Ordering {
Ord::cmp(&**self, &**other)
}
}
impl<'bump, T: 'bump + fmt::Debug> fmt::Debug for Vec<'bump, T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
fmt::Debug::fmt(&**self, f)
}
}
impl<'bump, T: 'bump> AsRef<Vec<'bump, T>> for Vec<'bump, T> {
fn as_ref(&self) -> &Vec<'bump, T> {
self
}
}
impl<'bump, T: 'bump> AsMut<Vec<'bump, T>> for Vec<'bump, T> {
fn as_mut(&mut self) -> &mut Vec<'bump, T> {
self
}
}
impl<'bump, T: 'bump> AsRef<[T]> for Vec<'bump, T> {
fn as_ref(&self) -> &[T] {
self
}
}
impl<'bump, T: 'bump> AsMut<[T]> for Vec<'bump, T> {
fn as_mut(&mut self) -> &mut [T] {
self
}
}
#[cfg(feature = "boxed")]
impl<'bump, T: 'bump> From<Vec<'bump, T>> for crate::boxed::Box<'bump, [T]> {
fn from(v: Vec<'bump, T>) -> crate::boxed::Box<'bump, [T]> {
v.into_boxed_slice()
}
}
impl<'bump, T: 'bump> Borrow<[T]> for Vec<'bump, T> {
#[inline]
fn borrow(&self) -> &[T] {
&self[..]
}
}
impl<'bump, T: 'bump> BorrowMut<[T]> for Vec<'bump, T> {
#[inline]
fn borrow_mut(&mut self) -> &mut [T] {
&mut self[..]
}
}
impl<'bump, T> Drop for Vec<'bump, T> {
fn drop(&mut self) {
unsafe {
// use drop for [T]
// use a raw slice to refer to the elements of the vector as weakest necessary type;
// could avoid questions of validity in certain cases
ptr::drop_in_place(ptr::slice_from_raw_parts_mut(self.as_mut_ptr(), self.len))
}
// RawVec handles deallocation
}
}
////////////////////////////////////////////////////////////////////////////////
// Clone-on-write
////////////////////////////////////////////////////////////////////////////////
// impl<'a, 'bump, T: Clone> From<Vec<'bump, T>> for Cow<'a, [T]> {
// fn from(v: Vec<'bump, T>) -> Cow<'a, [T]> {
// Cow::Owned(v)
// }
// }
// impl<'a, 'bump, T: Clone> From<&'a Vec<'bump, T>> for Cow<'a, [T]> {
// fn from(v: &'a Vec<'bump, T>) -> Cow<'a, [T]> {
// Cow::Borrowed(v.as_slice())
// }
// }
////////////////////////////////////////////////////////////////////////////////
// Iterators
////////////////////////////////////////////////////////////////////////////////
/// An iterator that moves out of a vector.
///
/// This `struct` is created by the [`Vec::into_iter`] method
/// (provided by the [`IntoIterator`] trait).
///
/// [`IntoIterator`]: https://doc.rust-lang.org/std/iter/trait.IntoIterator.html
pub struct IntoIter<'bump, T> {
phantom: PhantomData<&'bump [T]>,
ptr: *const T,
end: *const T,
}
impl<'bump, T: fmt::Debug> fmt::Debug for IntoIter<'bump, T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_tuple("IntoIter").field(&self.as_slice()).finish()
}
}
impl<'bump, T: 'bump> IntoIter<'bump, T> {
/// Returns the remaining items of this iterator as a slice.
///
/// # Examples
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let vec = bumpalo::vec![in &b; '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']);
/// ```
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
///
/// ```
/// use bumpalo::{Bump, collections::Vec};
///
/// let b = Bump::new();
///
/// let vec = bumpalo::vec![in &b; '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');
/// ```
pub fn as_mut_slice(&mut self) -> &mut [T] {
unsafe { slice::from_raw_parts_mut(self.ptr as *mut T, self.len()) }
}
}
unsafe impl<'bump, T: Send> Send for IntoIter<'bump, T> {}
unsafe impl<'bump, T: Sync> Sync for IntoIter<'bump, T> {}
impl<'bump, T: 'bump> Iterator for IntoIter<'bump, T> {
type Item = T;
#[inline]
fn next(&mut self) -> Option<T> {
unsafe {
if self.ptr as *const _ == self.end {
None
} else if mem::size_of::<T>() == 0 {
// purposefully don't use 'ptr.offset' because for
// vectors with 0-size elements this would return the
// same pointer.
self.ptr = arith_offset(self.ptr as *const i8, 1) as *mut T;
// Make up a value of this ZST.
Some(mem::zeroed())
} else {
let old = self.ptr;
self.ptr = self.ptr.offset(1);
Some(ptr::read(old))
}
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
let exact = if mem::size_of::<T>() == 0 {
(self.end as usize).wrapping_sub(self.ptr as usize)
} else {
unsafe { offset_from(self.end, self.ptr) as usize }
};
(exact, Some(exact))
}
#[inline]
fn count(self) -> usize {
self.len()
}
}
impl<'bump, T: 'bump> DoubleEndedIterator for IntoIter<'bump, T> {
#[inline]
fn next_back(&mut self) -> Option<T> {
unsafe {
if self.end == self.ptr {
None
} else if mem::size_of::<T>() == 0 {
// See above for why 'ptr.offset' isn't used
self.end = arith_offset(self.end as *const i8, -1) as *mut T;
// Make up a value of this ZST.
Some(mem::zeroed())
} else {
self.end = self.end.offset(-1);
Some(ptr::read(self.end))
}
}
}
}
impl<'bump, T: 'bump> ExactSizeIterator for IntoIter<'bump, T> {}
impl<'bump, T: 'bump> FusedIterator for IntoIter<'bump, T> {}
impl<'bump, T> Drop for IntoIter<'bump, T> {
fn drop(&mut self) {
// drop all remaining elements
self.for_each(drop);
}
}
/// A draining iterator for `Vec<'bump, T>`.
///
/// This `struct` is created by the [`Vec::drain`] method.
pub struct Drain<'a, 'bump, T: 'a + 'bump> {
/// 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<'bump, T>>,
}
impl<'a, 'bump, T: 'a + 'bump + fmt::Debug> fmt::Debug for Drain<'a, 'bump, T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_tuple("Drain").field(&self.iter.as_slice()).finish()
}
}
unsafe impl<'a, 'bump, T: Sync> Sync for Drain<'a, 'bump, T> {}
unsafe impl<'a, 'bump, T: Send> Send for Drain<'a, 'bump, T> {}
impl<'a, 'bump, T> Iterator for Drain<'a, 'bump, 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()
}
}
impl<'a, 'bump, T> DoubleEndedIterator for Drain<'a, 'bump, T> {
#[inline]
fn next_back(&mut self) -> Option<T> {
self.iter
.next_back()
.map(|elt| unsafe { ptr::read(elt as *const _) })
}
}
impl<'a, 'bump, T> Drop for Drain<'a, 'bump, 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().add(tail);
let dst = source_vec.as_mut_ptr().add(start);
ptr::copy(src, dst, self.tail_len);
}
source_vec.set_len(start + self.tail_len);
}
}
}
}
impl<'a, 'bump, T> ExactSizeIterator for Drain<'a, 'bump, T> {}
impl<'a, 'bump, T> FusedIterator for Drain<'a, 'bump, T> {}
/// A splicing iterator for `Vec`.
///
/// This struct is created by the [`Vec::splice`] method. See its
/// documentation for more information.
#[derive(Debug)]
pub struct Splice<'a, 'bump, I: Iterator + 'a + 'bump> {
drain: Drain<'a, 'bump, I::Item>,
replace_with: I,
}
impl<'a, 'bump, I: Iterator> Iterator for Splice<'a, 'bump, 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()
}
}
impl<'a, 'bump, I: Iterator> DoubleEndedIterator for Splice<'a, 'bump, I> {
fn next_back(&mut self) -> Option<Self::Item> {
self.drain.next_back()
}
}
impl<'a, 'bump, I: Iterator> ExactSizeIterator for Splice<'a, 'bump, I> {}
impl<'a, 'bump, I: Iterator> Drop for Splice<'a, 'bump, 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 = Vec::new_in(self.drain.vec.as_ref().buf.bump());
collected.extend(self.replace_with.by_ref());
let mut collected = collected.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, 'bump, T> Drain<'a, 'bump, 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().add(range_start), range_end - range_start);
for place in range_slice {
if let Some(new_item) = replace_with.next() {
ptr::write(place, new_item);
vec.len += 1;
} else {
return false;
}
}
true
}
/// 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().add(self.tail_start);
let dst = vec.as_mut_ptr().add(new_tail_start);
ptr::copy(src, dst, self.tail_len);
self.tail_start = new_tail_start;
}
}
/// An iterator produced by calling [`Vec::drain_filter`].
#[derive(Debug)]
pub struct DrainFilter<'a, 'bump: 'a, T: 'a + 'bump, F>
where
F: FnMut(&mut T) -> bool,
{
vec: &'a mut Vec<'bump, T>,
idx: usize,
del: usize,
old_len: usize,
pred: F,
}
impl<'a, 'bump, T, F> Iterator for DrainFilter<'a, 'bump, 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))
}
}
impl<'a, 'bump, T, F> Drop for DrainFilter<'a, 'bump, 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);
}
}
}
Sindbad File Manager Version 1.0, Coded By Sindbad EG ~ The Terrorists