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Diffstat (limited to 'third_party/rust/bumpalo/src/collections/vec.rs')
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diff --git a/third_party/rust/bumpalo/src/collections/vec.rs b/third_party/rust/bumpalo/src/collections/vec.rs new file mode 100644 index 0000000000..312aa055b9 --- /dev/null +++ b/third_party/rust/bumpalo/src/collections/vec.rs @@ -0,0 +1,2614 @@ +// 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); + } + } +} |