2133 lines
65 KiB
Rust
2133 lines
65 KiB
Rust
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! Small vectors in various sizes. These store a certain number of elements inline, and fall back
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//! to the heap for larger allocations. This can be a useful optimization for improving cache
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//! locality and reducing allocator traffic for workloads that fit within the inline buffer.
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//!
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//! ## `no_std` support
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//!
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//! By default, `smallvec` does not depend on `std`. However, the optional
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//! `write` feature implements the `std::io::Write` trait for vectors of `u8`.
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//! When this feature is enabled, `smallvec` depends on `std`.
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//!
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//! ## Optional features
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//!
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//! ### `serde`
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//!
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//! When this optional dependency is enabled, `SmallVec` implements the `serde::Serialize` and
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//! `serde::Deserialize` traits.
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//!
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//! ### `write`
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//!
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//! When this feature is enabled, `SmallVec<[u8; _]>` implements the `std::io::Write` trait.
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//! This feature is not compatible with `#![no_std]` programs.
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//!
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//! ### `union`
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//!
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//! **This feature requires Rust 1.49.**
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//!
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//! When the `union` feature is enabled `smallvec` will track its state (inline or spilled)
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//! without the use of an enum tag, reducing the size of the `smallvec` by one machine word.
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//! This means that there is potentially no space overhead compared to `Vec`.
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//! Note that `smallvec` can still be larger than `Vec` if the inline buffer is larger than two
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//! machine words.
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//!
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//! To use this feature add `features = ["union"]` in the `smallvec` section of Cargo.toml.
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//! Note that this feature requires Rust 1.49.
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//!
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//! Tracking issue: [rust-lang/rust#55149](https://github.com/rust-lang/rust/issues/55149)
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//!
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//! ### `const_generics`
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//!
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//! **This feature requires Rust 1.51.**
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//!
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//! When this feature is enabled, `SmallVec` works with any arrays of any size, not just a fixed
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//! list of sizes.
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//!
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//! ### `const_new`
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//!
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//! **This feature requires Rust 1.51.**
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//!
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//! This feature exposes the functions [`SmallVec::new_const`], [`SmallVec::from_const`], and [`smallvec_inline`] which enables the `SmallVec` to be initialized from a const context.
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//! For details, see the
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//! [Rust Reference](https://doc.rust-lang.org/reference/const_eval.html#const-functions).
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//!
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//! ### `specialization`
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//!
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//! **This feature is unstable and requires a nightly build of the Rust toolchain.**
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//!
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//! When this feature is enabled, `SmallVec::from(slice)` has improved performance for slices
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//! of `Copy` types. (Without this feature, you can use `SmallVec::from_slice` to get optimal
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//! performance for `Copy` types.)
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//!
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//! Tracking issue: [rust-lang/rust#31844](https://github.com/rust-lang/rust/issues/31844)
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//!
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//! ### `may_dangle`
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//!
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//! **This feature is unstable and requires a nightly build of the Rust toolchain.**
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//!
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//! This feature makes the Rust compiler less strict about use of vectors that contain borrowed
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//! references. For details, see the
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//! [Rustonomicon](https://doc.rust-lang.org/1.42.0/nomicon/dropck.html#an-escape-hatch).
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//!
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//! Tracking issue: [rust-lang/rust#34761](https://github.com/rust-lang/rust/issues/34761)
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#![no_std]
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#![cfg_attr(docsrs, feature(doc_cfg))]
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#![cfg_attr(feature = "specialization", allow(incomplete_features))]
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#![cfg_attr(feature = "specialization", feature(specialization))]
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#![cfg_attr(feature = "may_dangle", feature(dropck_eyepatch))]
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#![cfg_attr(
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feature = "debugger_visualizer",
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feature(debugger_visualizer),
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debugger_visualizer(natvis_file = "../debug_metadata/smallvec.natvis")
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)]
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#![deny(missing_docs)]
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#[doc(hidden)]
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pub extern crate alloc;
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#[cfg(any(test, feature = "write"))]
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extern crate std;
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#[cfg(test)]
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mod tests;
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#[allow(deprecated)]
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use alloc::alloc::{Layout, LayoutErr};
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use alloc::boxed::Box;
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use alloc::{vec, vec::Vec};
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use core::borrow::{Borrow, BorrowMut};
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use core::cmp;
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use core::fmt;
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use core::hash::{Hash, Hasher};
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use core::hint::unreachable_unchecked;
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use core::iter::{repeat, FromIterator, FusedIterator, IntoIterator};
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use core::mem;
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use core::mem::MaybeUninit;
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use core::ops::{self, Range, RangeBounds};
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use core::ptr::{self, NonNull};
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use core::slice::{self, SliceIndex};
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#[cfg(feature = "serde")]
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use serde::{
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de::{Deserialize, Deserializer, SeqAccess, Visitor},
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ser::{Serialize, SerializeSeq, Serializer},
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};
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#[cfg(feature = "serde")]
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use core::marker::PhantomData;
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#[cfg(feature = "write")]
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use std::io;
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/// Creates a [`SmallVec`] containing the arguments.
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///
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/// `smallvec!` allows `SmallVec`s to be defined with the same syntax as array expressions.
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/// There are two forms of this macro:
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///
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/// - Create a [`SmallVec`] containing a given list of elements:
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///
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/// ```
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/// # #[macro_use] extern crate smallvec;
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/// # use smallvec::SmallVec;
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/// # fn main() {
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/// let v: SmallVec<[_; 128]> = smallvec![1, 2, 3];
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/// assert_eq!(v[0], 1);
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/// assert_eq!(v[1], 2);
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/// assert_eq!(v[2], 3);
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/// # }
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/// ```
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///
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/// - Create a [`SmallVec`] from a given element and size:
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///
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/// ```
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/// # #[macro_use] extern crate smallvec;
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/// # use smallvec::SmallVec;
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/// # fn main() {
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/// let v: SmallVec<[_; 0x8000]> = smallvec![1; 3];
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/// assert_eq!(v, SmallVec::from_buf([1, 1, 1]));
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/// # }
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/// ```
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///
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/// Note that unlike array expressions this syntax supports all elements
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/// which implement [`Clone`] and the number of elements doesn't have to be
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/// a constant.
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///
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/// This will use `clone` to duplicate an expression, so one should be careful
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/// using this with types having a nonstandard `Clone` implementation. For
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/// example, `smallvec![Rc::new(1); 5]` will create a vector of five references
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/// to the same boxed integer value, not five references pointing to independently
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/// boxed integers.
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#[macro_export]
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macro_rules! smallvec {
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// count helper: transform any expression into 1
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(@one $x:expr) => (1usize);
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($elem:expr; $n:expr) => ({
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$crate::SmallVec::from_elem($elem, $n)
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});
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($($x:expr),*$(,)*) => ({
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let count = 0usize $(+ $crate::smallvec!(@one $x))*;
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#[allow(unused_mut)]
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let mut vec = $crate::SmallVec::new();
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if count <= vec.inline_size() {
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$(vec.push($x);)*
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vec
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} else {
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$crate::SmallVec::from_vec($crate::alloc::vec![$($x,)*])
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}
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});
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}
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/// Creates an inline [`SmallVec`] containing the arguments. This macro is enabled by the feature `const_new`.
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///
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/// `smallvec_inline!` allows `SmallVec`s to be defined with the same syntax as array expressions in `const` contexts.
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/// The inline storage `A` will always be an array of the size specified by the arguments.
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/// There are two forms of this macro:
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///
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/// - Create a [`SmallVec`] containing a given list of elements:
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///
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/// ```
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/// # #[macro_use] extern crate smallvec;
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/// # use smallvec::SmallVec;
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/// # fn main() {
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/// const V: SmallVec<[i32; 3]> = smallvec_inline![1, 2, 3];
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/// assert_eq!(V[0], 1);
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/// assert_eq!(V[1], 2);
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/// assert_eq!(V[2], 3);
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/// # }
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/// ```
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///
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/// - Create a [`SmallVec`] from a given element and size:
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///
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/// ```
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/// # #[macro_use] extern crate smallvec;
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/// # use smallvec::SmallVec;
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/// # fn main() {
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/// const V: SmallVec<[i32; 3]> = smallvec_inline![1; 3];
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/// assert_eq!(V, SmallVec::from_buf([1, 1, 1]));
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/// # }
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/// ```
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///
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/// Note that the behavior mimics that of array expressions, in contrast to [`smallvec`].
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#[cfg(feature = "const_new")]
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#[cfg_attr(docsrs, doc(cfg(feature = "const_new")))]
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#[macro_export]
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macro_rules! smallvec_inline {
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// count helper: transform any expression into 1
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(@one $x:expr) => (1usize);
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($elem:expr; $n:expr) => ({
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$crate::SmallVec::<[_; $n]>::from_const([$elem; $n])
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});
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($($x:expr),+ $(,)?) => ({
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const N: usize = 0usize $(+ $crate::smallvec_inline!(@one $x))*;
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$crate::SmallVec::<[_; N]>::from_const([$($x,)*])
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});
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}
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/// `panic!()` in debug builds, optimization hint in release.
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#[cfg(not(feature = "union"))]
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macro_rules! debug_unreachable {
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() => {
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debug_unreachable!("entered unreachable code")
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};
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($e:expr) => {
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if cfg!(not(debug_assertions)) {
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unreachable_unchecked();
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} else {
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panic!($e);
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}
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};
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}
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/// Trait to be implemented by a collection that can be extended from a slice
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///
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/// ## Example
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///
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/// ```rust
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/// use smallvec::{ExtendFromSlice, SmallVec};
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///
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/// fn initialize<V: ExtendFromSlice<u8>>(v: &mut V) {
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/// v.extend_from_slice(b"Test!");
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/// }
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///
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/// let mut vec = Vec::new();
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/// initialize(&mut vec);
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/// assert_eq!(&vec, b"Test!");
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///
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/// let mut small_vec = SmallVec::<[u8; 8]>::new();
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/// initialize(&mut small_vec);
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/// assert_eq!(&small_vec as &[_], b"Test!");
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/// ```
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#[doc(hidden)]
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#[deprecated]
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pub trait ExtendFromSlice<T> {
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/// Extends a collection from a slice of its element type
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fn extend_from_slice(&mut self, other: &[T]);
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}
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#[allow(deprecated)]
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impl<T: Clone> ExtendFromSlice<T> for Vec<T> {
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fn extend_from_slice(&mut self, other: &[T]) {
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Vec::extend_from_slice(self, other)
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}
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}
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/// Error type for APIs with fallible heap allocation
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#[derive(Debug)]
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pub enum CollectionAllocErr {
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/// Overflow `usize::MAX` or other error during size computation
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CapacityOverflow,
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/// The allocator return an error
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AllocErr {
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/// The layout that was passed to the allocator
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layout: Layout,
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},
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}
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impl fmt::Display for CollectionAllocErr {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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write!(f, "Allocation error: {:?}", self)
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}
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}
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#[allow(deprecated)]
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impl From<LayoutErr> for CollectionAllocErr {
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fn from(_: LayoutErr) -> Self {
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CollectionAllocErr::CapacityOverflow
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}
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}
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fn infallible<T>(result: Result<T, CollectionAllocErr>) -> T {
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match result {
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Ok(x) => x,
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Err(CollectionAllocErr::CapacityOverflow) => panic!("capacity overflow"),
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Err(CollectionAllocErr::AllocErr { layout }) => alloc::alloc::handle_alloc_error(layout),
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}
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}
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/// FIXME: use `Layout::array` when we require a Rust version where it’s stable
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/// https://github.com/rust-lang/rust/issues/55724
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fn layout_array<T>(n: usize) -> Result<Layout, CollectionAllocErr> {
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let size = mem::size_of::<T>()
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.checked_mul(n)
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.ok_or(CollectionAllocErr::CapacityOverflow)?;
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let align = mem::align_of::<T>();
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Layout::from_size_align(size, align).map_err(|_| CollectionAllocErr::CapacityOverflow)
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}
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unsafe fn deallocate<T>(ptr: *mut T, capacity: usize) {
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// This unwrap should succeed since the same did when allocating.
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let layout = layout_array::<T>(capacity).unwrap();
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alloc::alloc::dealloc(ptr as *mut u8, layout)
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}
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/// An iterator that removes the items from a `SmallVec` and yields them by value.
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///
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/// Returned from [`SmallVec::drain`][1].
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///
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/// [1]: struct.SmallVec.html#method.drain
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pub struct Drain<'a, T: 'a + Array> {
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tail_start: usize,
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tail_len: usize,
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iter: slice::Iter<'a, T::Item>,
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vec: NonNull<SmallVec<T>>,
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}
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impl<'a, T: 'a + Array> fmt::Debug for Drain<'a, T>
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where
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T::Item: fmt::Debug,
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{
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||
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.debug_tuple("Drain").field(&self.iter.as_slice()).finish()
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}
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}
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unsafe impl<'a, T: Sync + Array> Sync for Drain<'a, T> {}
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unsafe impl<'a, T: Send + Array> Send for Drain<'a, T> {}
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impl<'a, T: 'a + Array> Iterator for Drain<'a, T> {
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type Item = T::Item;
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#[inline]
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fn next(&mut self) -> Option<T::Item> {
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self.iter
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.next()
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.map(|reference| unsafe { ptr::read(reference) })
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}
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#[inline]
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fn size_hint(&self) -> (usize, Option<usize>) {
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self.iter.size_hint()
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}
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}
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impl<'a, T: 'a + Array> DoubleEndedIterator for Drain<'a, T> {
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#[inline]
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fn next_back(&mut self) -> Option<T::Item> {
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self.iter
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.next_back()
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.map(|reference| unsafe { ptr::read(reference) })
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}
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}
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impl<'a, T: Array> ExactSizeIterator for Drain<'a, T> {
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||
#[inline]
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fn len(&self) -> usize {
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self.iter.len()
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}
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}
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|
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impl<'a, T: Array> FusedIterator for Drain<'a, T> {}
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impl<'a, T: 'a + Array> Drop for Drain<'a, T> {
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fn drop(&mut self) {
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self.for_each(drop);
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|
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if self.tail_len > 0 {
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unsafe {
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||
let source_vec = self.vec.as_mut();
|
||
|
||
// memmove back untouched tail, update to new length
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||
let start = source_vec.len();
|
||
let tail = self.tail_start;
|
||
if tail != start {
|
||
// as_mut_ptr creates a &mut, invalidating other pointers.
|
||
// This pattern avoids calling it with a pointer already present.
|
||
let ptr = source_vec.as_mut_ptr();
|
||
let src = ptr.add(tail);
|
||
let dst = ptr.add(start);
|
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ptr::copy(src, dst, self.tail_len);
|
||
}
|
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source_vec.set_len(start + self.tail_len);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
#[cfg(feature = "union")]
|
||
union SmallVecData<A: Array> {
|
||
inline: core::mem::ManuallyDrop<MaybeUninit<A>>,
|
||
heap: (*mut A::Item, usize),
|
||
}
|
||
|
||
#[cfg(all(feature = "union", feature = "const_new"))]
|
||
impl<T, const N: usize> SmallVecData<[T; N]> {
|
||
#[cfg_attr(docsrs, doc(cfg(feature = "const_new")))]
|
||
#[inline]
|
||
const fn from_const(inline: MaybeUninit<[T; N]>) -> Self {
|
||
SmallVecData {
|
||
inline: core::mem::ManuallyDrop::new(inline),
|
||
}
|
||
}
|
||
}
|
||
|
||
#[cfg(feature = "union")]
|
||
impl<A: Array> SmallVecData<A> {
|
||
#[inline]
|
||
unsafe fn inline(&self) -> *const A::Item {
|
||
self.inline.as_ptr() as *const A::Item
|
||
}
|
||
#[inline]
|
||
unsafe fn inline_mut(&mut self) -> *mut A::Item {
|
||
self.inline.as_mut_ptr() as *mut A::Item
|
||
}
|
||
#[inline]
|
||
fn from_inline(inline: MaybeUninit<A>) -> SmallVecData<A> {
|
||
SmallVecData {
|
||
inline: core::mem::ManuallyDrop::new(inline),
|
||
}
|
||
}
|
||
#[inline]
|
||
unsafe fn into_inline(self) -> MaybeUninit<A> {
|
||
core::mem::ManuallyDrop::into_inner(self.inline)
|
||
}
|
||
#[inline]
|
||
unsafe fn heap(&self) -> (*mut A::Item, usize) {
|
||
self.heap
|
||
}
|
||
#[inline]
|
||
unsafe fn heap_mut(&mut self) -> &mut (*mut A::Item, usize) {
|
||
&mut self.heap
|
||
}
|
||
#[inline]
|
||
fn from_heap(ptr: *mut A::Item, len: usize) -> SmallVecData<A> {
|
||
SmallVecData { heap: (ptr, len) }
|
||
}
|
||
}
|
||
|
||
#[cfg(not(feature = "union"))]
|
||
enum SmallVecData<A: Array> {
|
||
Inline(MaybeUninit<A>),
|
||
Heap((*mut A::Item, usize)),
|
||
}
|
||
|
||
#[cfg(all(not(feature = "union"), feature = "const_new"))]
|
||
impl<T, const N: usize> SmallVecData<[T; N]> {
|
||
#[cfg_attr(docsrs, doc(cfg(feature = "const_new")))]
|
||
#[inline]
|
||
const fn from_const(inline: MaybeUninit<[T; N]>) -> Self {
|
||
SmallVecData::Inline(inline)
|
||
}
|
||
}
|
||
|
||
#[cfg(not(feature = "union"))]
|
||
impl<A: Array> SmallVecData<A> {
|
||
#[inline]
|
||
unsafe fn inline(&self) -> *const A::Item {
|
||
match self {
|
||
SmallVecData::Inline(a) => a.as_ptr() as *const A::Item,
|
||
_ => debug_unreachable!(),
|
||
}
|
||
}
|
||
#[inline]
|
||
unsafe fn inline_mut(&mut self) -> *mut A::Item {
|
||
match self {
|
||
SmallVecData::Inline(a) => a.as_mut_ptr() as *mut A::Item,
|
||
_ => debug_unreachable!(),
|
||
}
|
||
}
|
||
#[inline]
|
||
fn from_inline(inline: MaybeUninit<A>) -> SmallVecData<A> {
|
||
SmallVecData::Inline(inline)
|
||
}
|
||
#[inline]
|
||
unsafe fn into_inline(self) -> MaybeUninit<A> {
|
||
match self {
|
||
SmallVecData::Inline(a) => a,
|
||
_ => debug_unreachable!(),
|
||
}
|
||
}
|
||
#[inline]
|
||
unsafe fn heap(&self) -> (*mut A::Item, usize) {
|
||
match self {
|
||
SmallVecData::Heap(data) => *data,
|
||
_ => debug_unreachable!(),
|
||
}
|
||
}
|
||
#[inline]
|
||
unsafe fn heap_mut(&mut self) -> &mut (*mut A::Item, usize) {
|
||
match self {
|
||
SmallVecData::Heap(data) => data,
|
||
_ => debug_unreachable!(),
|
||
}
|
||
}
|
||
#[inline]
|
||
fn from_heap(ptr: *mut A::Item, len: usize) -> SmallVecData<A> {
|
||
SmallVecData::Heap((ptr, len))
|
||
}
|
||
}
|
||
|
||
unsafe impl<A: Array + Send> Send for SmallVecData<A> {}
|
||
unsafe impl<A: Array + Sync> Sync for SmallVecData<A> {}
|
||
|
||
/// A `Vec`-like container that can store a small number of elements inline.
|
||
///
|
||
/// `SmallVec` acts like a vector, but can store a limited amount of data inline within the
|
||
/// `SmallVec` struct rather than in a separate allocation. If the data exceeds this limit, the
|
||
/// `SmallVec` will "spill" its data onto the heap, allocating a new buffer to hold it.
|
||
///
|
||
/// The amount of data that a `SmallVec` can store inline depends on its backing store. The backing
|
||
/// store can be any type that implements the `Array` trait; usually it is a small fixed-sized
|
||
/// array. For example a `SmallVec<[u64; 8]>` can hold up to eight 64-bit integers inline.
|
||
///
|
||
/// ## Example
|
||
///
|
||
/// ```rust
|
||
/// use smallvec::SmallVec;
|
||
/// let mut v = SmallVec::<[u8; 4]>::new(); // initialize an empty vector
|
||
///
|
||
/// // The vector can hold up to 4 items without spilling onto the heap.
|
||
/// v.extend(0..4);
|
||
/// assert_eq!(v.len(), 4);
|
||
/// assert!(!v.spilled());
|
||
///
|
||
/// // Pushing another element will force the buffer to spill:
|
||
/// v.push(4);
|
||
/// assert_eq!(v.len(), 5);
|
||
/// assert!(v.spilled());
|
||
/// ```
|
||
pub struct SmallVec<A: Array> {
|
||
// The capacity field is used to determine which of the storage variants is active:
|
||
// If capacity <= Self::inline_capacity() then the inline variant is used and capacity holds the current length of the vector (number of elements actually in use).
|
||
// If capacity > Self::inline_capacity() then the heap variant is used and capacity holds the size of the memory allocation.
|
||
capacity: usize,
|
||
data: SmallVecData<A>,
|
||
}
|
||
|
||
impl<A: Array> SmallVec<A> {
|
||
/// Construct an empty vector
|
||
#[inline]
|
||
pub fn new() -> SmallVec<A> {
|
||
// Try to detect invalid custom implementations of `Array`. Hopefully,
|
||
// this check should be optimized away entirely for valid ones.
|
||
assert!(
|
||
mem::size_of::<A>() == A::size() * mem::size_of::<A::Item>()
|
||
&& mem::align_of::<A>() >= mem::align_of::<A::Item>()
|
||
);
|
||
SmallVec {
|
||
capacity: 0,
|
||
data: SmallVecData::from_inline(MaybeUninit::uninit()),
|
||
}
|
||
}
|
||
|
||
/// Construct an empty vector with enough capacity pre-allocated to store at least `n`
|
||
/// elements.
|
||
///
|
||
/// Will create a heap allocation only if `n` is larger than the inline capacity.
|
||
///
|
||
/// ```
|
||
/// # use smallvec::SmallVec;
|
||
///
|
||
/// let v: SmallVec<[u8; 3]> = SmallVec::with_capacity(100);
|
||
///
|
||
/// assert!(v.is_empty());
|
||
/// assert!(v.capacity() >= 100);
|
||
/// ```
|
||
#[inline]
|
||
pub fn with_capacity(n: usize) -> Self {
|
||
let mut v = SmallVec::new();
|
||
v.reserve_exact(n);
|
||
v
|
||
}
|
||
|
||
/// Construct a new `SmallVec` from a `Vec<A::Item>`.
|
||
///
|
||
/// Elements will be copied to the inline buffer if vec.capacity() <= Self::inline_capacity().
|
||
///
|
||
/// ```rust
|
||
/// use smallvec::SmallVec;
|
||
///
|
||
/// let vec = vec![1, 2, 3, 4, 5];
|
||
/// let small_vec: SmallVec<[_; 3]> = SmallVec::from_vec(vec);
|
||
///
|
||
/// assert_eq!(&*small_vec, &[1, 2, 3, 4, 5]);
|
||
/// ```
|
||
#[inline]
|
||
pub fn from_vec(mut vec: Vec<A::Item>) -> SmallVec<A> {
|
||
if vec.capacity() <= Self::inline_capacity() {
|
||
unsafe {
|
||
let mut data = SmallVecData::<A>::from_inline(MaybeUninit::uninit());
|
||
let len = vec.len();
|
||
vec.set_len(0);
|
||
ptr::copy_nonoverlapping(vec.as_ptr(), data.inline_mut(), len);
|
||
|
||
SmallVec {
|
||
capacity: len,
|
||
data,
|
||
}
|
||
}
|
||
} else {
|
||
let (ptr, cap, len) = (vec.as_mut_ptr(), vec.capacity(), vec.len());
|
||
mem::forget(vec);
|
||
|
||
SmallVec {
|
||
capacity: cap,
|
||
data: SmallVecData::from_heap(ptr, len),
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Constructs a new `SmallVec` on the stack from an `A` without
|
||
/// copying elements.
|
||
///
|
||
/// ```rust
|
||
/// use smallvec::SmallVec;
|
||
///
|
||
/// let buf = [1, 2, 3, 4, 5];
|
||
/// let small_vec: SmallVec<_> = SmallVec::from_buf(buf);
|
||
///
|
||
/// assert_eq!(&*small_vec, &[1, 2, 3, 4, 5]);
|
||
/// ```
|
||
#[inline]
|
||
pub fn from_buf(buf: A) -> SmallVec<A> {
|
||
SmallVec {
|
||
capacity: A::size(),
|
||
data: SmallVecData::from_inline(MaybeUninit::new(buf)),
|
||
}
|
||
}
|
||
|
||
/// Constructs a new `SmallVec` on the stack from an `A` without
|
||
/// copying elements. Also sets the length, which must be less or
|
||
/// equal to the size of `buf`.
|
||
///
|
||
/// ```rust
|
||
/// use smallvec::SmallVec;
|
||
///
|
||
/// let buf = [1, 2, 3, 4, 5, 0, 0, 0];
|
||
/// let small_vec: SmallVec<_> = SmallVec::from_buf_and_len(buf, 5);
|
||
///
|
||
/// assert_eq!(&*small_vec, &[1, 2, 3, 4, 5]);
|
||
/// ```
|
||
#[inline]
|
||
pub fn from_buf_and_len(buf: A, len: usize) -> SmallVec<A> {
|
||
assert!(len <= A::size());
|
||
unsafe { SmallVec::from_buf_and_len_unchecked(MaybeUninit::new(buf), len) }
|
||
}
|
||
|
||
/// Constructs a new `SmallVec` on the stack from an `A` without
|
||
/// copying elements. Also sets the length. The user is responsible
|
||
/// for ensuring that `len <= A::size()`.
|
||
///
|
||
/// ```rust
|
||
/// use smallvec::SmallVec;
|
||
/// use std::mem::MaybeUninit;
|
||
///
|
||
/// let buf = [1, 2, 3, 4, 5, 0, 0, 0];
|
||
/// let small_vec: SmallVec<_> = unsafe {
|
||
/// SmallVec::from_buf_and_len_unchecked(MaybeUninit::new(buf), 5)
|
||
/// };
|
||
///
|
||
/// assert_eq!(&*small_vec, &[1, 2, 3, 4, 5]);
|
||
/// ```
|
||
#[inline]
|
||
pub unsafe fn from_buf_and_len_unchecked(buf: MaybeUninit<A>, len: usize) -> SmallVec<A> {
|
||
SmallVec {
|
||
capacity: len,
|
||
data: SmallVecData::from_inline(buf),
|
||
}
|
||
}
|
||
|
||
/// 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.
|
||
pub unsafe fn set_len(&mut self, new_len: usize) {
|
||
let (_, len_ptr, _) = self.triple_mut();
|
||
*len_ptr = new_len;
|
||
}
|
||
|
||
/// The maximum number of elements this vector can hold inline
|
||
#[inline]
|
||
fn inline_capacity() -> usize {
|
||
if mem::size_of::<A::Item>() > 0 {
|
||
A::size()
|
||
} else {
|
||
// For zero-size items code like `ptr.add(offset)` always returns the same pointer.
|
||
// Therefore all items are at the same address,
|
||
// and any array size has capacity for infinitely many items.
|
||
// The capacity is limited by the bit width of the length field.
|
||
//
|
||
// `Vec` also does this:
|
||
// https://github.com/rust-lang/rust/blob/1.44.0/src/liballoc/raw_vec.rs#L186
|
||
//
|
||
// In our case, this also ensures that a smallvec of zero-size items never spills,
|
||
// and we never try to allocate zero bytes which `std::alloc::alloc` disallows.
|
||
core::usize::MAX
|
||
}
|
||
}
|
||
|
||
/// The maximum number of elements this vector can hold inline
|
||
#[inline]
|
||
pub fn inline_size(&self) -> usize {
|
||
Self::inline_capacity()
|
||
}
|
||
|
||
/// The number of elements stored in the vector
|
||
#[inline]
|
||
pub fn len(&self) -> usize {
|
||
self.triple().1
|
||
}
|
||
|
||
/// Returns `true` if the vector is empty
|
||
#[inline]
|
||
pub fn is_empty(&self) -> bool {
|
||
self.len() == 0
|
||
}
|
||
|
||
/// The number of items the vector can hold without reallocating
|
||
#[inline]
|
||
pub fn capacity(&self) -> usize {
|
||
self.triple().2
|
||
}
|
||
|
||
/// Returns a tuple with (data ptr, len, capacity)
|
||
/// Useful to get all SmallVec properties with a single check of the current storage variant.
|
||
#[inline]
|
||
fn triple(&self) -> (*const A::Item, usize, usize) {
|
||
unsafe {
|
||
if self.spilled() {
|
||
let (ptr, len) = self.data.heap();
|
||
(ptr, len, self.capacity)
|
||
} else {
|
||
(self.data.inline(), self.capacity, Self::inline_capacity())
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Returns a tuple with (data ptr, len ptr, capacity)
|
||
#[inline]
|
||
fn triple_mut(&mut self) -> (*mut A::Item, &mut usize, usize) {
|
||
unsafe {
|
||
if self.spilled() {
|
||
let &mut (ptr, ref mut len_ptr) = self.data.heap_mut();
|
||
(ptr, len_ptr, self.capacity)
|
||
} else {
|
||
(
|
||
self.data.inline_mut(),
|
||
&mut self.capacity,
|
||
Self::inline_capacity(),
|
||
)
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Returns `true` if the data has spilled into a separate heap-allocated buffer.
|
||
#[inline]
|
||
pub fn spilled(&self) -> bool {
|
||
self.capacity > Self::inline_capacity()
|
||
}
|
||
|
||
/// 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.
|
||
pub fn drain<R>(&mut self, range: R) -> Drain<'_, A>
|
||
where
|
||
R: RangeBounds<usize>,
|
||
{
|
||
use core::ops::Bound::*;
|
||
|
||
let len = self.len();
|
||
let start = match range.start_bound() {
|
||
Included(&n) => n,
|
||
Excluded(&n) => n.checked_add(1).expect("Range start out of bounds"),
|
||
Unbounded => 0,
|
||
};
|
||
let end = match range.end_bound() {
|
||
Included(&n) => n.checked_add(1).expect("Range end out of bounds"),
|
||
Excluded(&n) => n,
|
||
Unbounded => len,
|
||
};
|
||
|
||
assert!(start <= end);
|
||
assert!(end <= len);
|
||
|
||
unsafe {
|
||
self.set_len(start);
|
||
|
||
let range_slice = slice::from_raw_parts(self.as_ptr().add(start), end - start);
|
||
|
||
Drain {
|
||
tail_start: end,
|
||
tail_len: len - end,
|
||
iter: range_slice.iter(),
|
||
// Since self is a &mut, passing it to a function would invalidate the slice iterator.
|
||
vec: NonNull::new_unchecked(self as *mut _),
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Append an item to the vector.
|
||
#[inline]
|
||
pub fn push(&mut self, value: A::Item) {
|
||
unsafe {
|
||
let (mut ptr, mut len, cap) = self.triple_mut();
|
||
if *len == cap {
|
||
self.reserve(1);
|
||
let &mut (heap_ptr, ref mut heap_len) = self.data.heap_mut();
|
||
ptr = heap_ptr;
|
||
len = heap_len;
|
||
}
|
||
ptr::write(ptr.add(*len), value);
|
||
*len += 1;
|
||
}
|
||
}
|
||
|
||
/// Remove an item from the end of the vector and return it, or None if empty.
|
||
#[inline]
|
||
pub fn pop(&mut self) -> Option<A::Item> {
|
||
unsafe {
|
||
let (ptr, len_ptr, _) = self.triple_mut();
|
||
if *len_ptr == 0 {
|
||
return None;
|
||
}
|
||
let last_index = *len_ptr - 1;
|
||
*len_ptr = last_index;
|
||
Some(ptr::read(ptr.add(last_index)))
|
||
}
|
||
}
|
||
|
||
/// Moves all the elements of `other` into `self`, leaving `other` empty.
|
||
///
|
||
/// # Example
|
||
///
|
||
/// ```
|
||
/// # use smallvec::{SmallVec, smallvec};
|
||
/// let mut v0: SmallVec<[u8; 16]> = smallvec![1, 2, 3];
|
||
/// let mut v1: SmallVec<[u8; 32]> = smallvec![4, 5, 6];
|
||
/// v0.append(&mut v1);
|
||
/// assert_eq!(*v0, [1, 2, 3, 4, 5, 6]);
|
||
/// assert_eq!(*v1, []);
|
||
/// ```
|
||
pub fn append<B>(&mut self, other: &mut SmallVec<B>)
|
||
where
|
||
B: Array<Item = A::Item>,
|
||
{
|
||
self.extend(other.drain(..))
|
||
}
|
||
|
||
/// Re-allocate to set the capacity to `max(new_cap, inline_size())`.
|
||
///
|
||
/// Panics if `new_cap` is less than the vector's length
|
||
/// or if the capacity computation overflows `usize`.
|
||
pub fn grow(&mut self, new_cap: usize) {
|
||
infallible(self.try_grow(new_cap))
|
||
}
|
||
|
||
/// Re-allocate to set the capacity to `max(new_cap, inline_size())`.
|
||
///
|
||
/// Panics if `new_cap` is less than the vector's length
|
||
pub fn try_grow(&mut self, new_cap: usize) -> Result<(), CollectionAllocErr> {
|
||
unsafe {
|
||
let (ptr, &mut len, cap) = self.triple_mut();
|
||
let unspilled = !self.spilled();
|
||
assert!(new_cap >= len);
|
||
if new_cap <= self.inline_size() {
|
||
if unspilled {
|
||
return Ok(());
|
||
}
|
||
self.data = SmallVecData::from_inline(MaybeUninit::uninit());
|
||
ptr::copy_nonoverlapping(ptr, self.data.inline_mut(), len);
|
||
self.capacity = len;
|
||
deallocate(ptr, cap);
|
||
} else if new_cap != cap {
|
||
let layout = layout_array::<A::Item>(new_cap)?;
|
||
debug_assert!(layout.size() > 0);
|
||
let new_alloc;
|
||
if unspilled {
|
||
new_alloc = NonNull::new(alloc::alloc::alloc(layout))
|
||
.ok_or(CollectionAllocErr::AllocErr { layout })?
|
||
.cast()
|
||
.as_ptr();
|
||
ptr::copy_nonoverlapping(ptr, new_alloc, len);
|
||
} else {
|
||
// This should never fail since the same succeeded
|
||
// when previously allocating `ptr`.
|
||
let old_layout = layout_array::<A::Item>(cap)?;
|
||
|
||
let new_ptr = alloc::alloc::realloc(ptr as *mut u8, old_layout, layout.size());
|
||
new_alloc = NonNull::new(new_ptr)
|
||
.ok_or(CollectionAllocErr::AllocErr { layout })?
|
||
.cast()
|
||
.as_ptr();
|
||
}
|
||
self.data = SmallVecData::from_heap(new_alloc, len);
|
||
self.capacity = new_cap;
|
||
}
|
||
Ok(())
|
||
}
|
||
}
|
||
|
||
/// Reserve capacity for `additional` more elements to be inserted.
|
||
///
|
||
/// May reserve more space to avoid frequent reallocations.
|
||
///
|
||
/// Panics if the capacity computation overflows `usize`.
|
||
#[inline]
|
||
pub fn reserve(&mut self, additional: usize) {
|
||
infallible(self.try_reserve(additional))
|
||
}
|
||
|
||
/// Reserve capacity for `additional` more elements to be inserted.
|
||
///
|
||
/// May reserve more space to avoid frequent reallocations.
|
||
pub fn try_reserve(&mut self, additional: usize) -> Result<(), CollectionAllocErr> {
|
||
// prefer triple_mut() even if triple() would work
|
||
// so that the optimizer removes duplicated calls to it
|
||
// from callers like insert()
|
||
let (_, &mut len, cap) = self.triple_mut();
|
||
if cap - len >= additional {
|
||
return Ok(());
|
||
}
|
||
let new_cap = len
|
||
.checked_add(additional)
|
||
.and_then(usize::checked_next_power_of_two)
|
||
.ok_or(CollectionAllocErr::CapacityOverflow)?;
|
||
self.try_grow(new_cap)
|
||
}
|
||
|
||
/// Reserve the minimum capacity for `additional` more elements to be inserted.
|
||
///
|
||
/// Panics if the new capacity overflows `usize`.
|
||
pub fn reserve_exact(&mut self, additional: usize) {
|
||
infallible(self.try_reserve_exact(additional))
|
||
}
|
||
|
||
/// Reserve the minimum capacity for `additional` more elements to be inserted.
|
||
pub fn try_reserve_exact(&mut self, additional: usize) -> Result<(), CollectionAllocErr> {
|
||
let (_, &mut len, cap) = self.triple_mut();
|
||
if cap - len >= additional {
|
||
return Ok(());
|
||
}
|
||
let new_cap = len
|
||
.checked_add(additional)
|
||
.ok_or(CollectionAllocErr::CapacityOverflow)?;
|
||
self.try_grow(new_cap)
|
||
}
|
||
|
||
/// Shrink the capacity of the vector as much as possible.
|
||
///
|
||
/// When possible, this will move data from an external heap buffer to the vector's inline
|
||
/// storage.
|
||
pub fn shrink_to_fit(&mut self) {
|
||
if !self.spilled() {
|
||
return;
|
||
}
|
||
let len = self.len();
|
||
if self.inline_size() >= len {
|
||
unsafe {
|
||
let (ptr, len) = self.data.heap();
|
||
self.data = SmallVecData::from_inline(MaybeUninit::uninit());
|
||
ptr::copy_nonoverlapping(ptr, self.data.inline_mut(), len);
|
||
deallocate(ptr, self.capacity);
|
||
self.capacity = len;
|
||
}
|
||
} else if self.capacity() > len {
|
||
self.grow(len);
|
||
}
|
||
}
|
||
|
||
/// Shorten the vector, keeping the first `len` elements and dropping the rest.
|
||
///
|
||
/// If `len` is greater than or equal to the vector's current length, this has no
|
||
/// effect.
|
||
///
|
||
/// This does not re-allocate. If you want the vector's capacity to shrink, call
|
||
/// `shrink_to_fit` after truncating.
|
||
pub fn truncate(&mut self, len: usize) {
|
||
unsafe {
|
||
let (ptr, len_ptr, _) = self.triple_mut();
|
||
while len < *len_ptr {
|
||
let last_index = *len_ptr - 1;
|
||
*len_ptr = last_index;
|
||
ptr::drop_in_place(ptr.add(last_index));
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Extracts a slice containing the entire vector.
|
||
///
|
||
/// Equivalent to `&s[..]`.
|
||
pub fn as_slice(&self) -> &[A::Item] {
|
||
self
|
||
}
|
||
|
||
/// Extracts a mutable slice of the entire vector.
|
||
///
|
||
/// Equivalent to `&mut s[..]`.
|
||
pub fn as_mut_slice(&mut self) -> &mut [A::Item] {
|
||
self
|
||
}
|
||
|
||
/// Remove the element at position `index`, replacing it with the last element.
|
||
///
|
||
/// This does not preserve ordering, but is O(1).
|
||
///
|
||
/// Panics if `index` is out of bounds.
|
||
#[inline]
|
||
pub fn swap_remove(&mut self, index: usize) -> A::Item {
|
||
let len = self.len();
|
||
self.swap(len - 1, index);
|
||
self.pop()
|
||
.unwrap_or_else(|| unsafe { unreachable_unchecked() })
|
||
}
|
||
|
||
/// Remove all elements from the vector.
|
||
#[inline]
|
||
pub fn clear(&mut self) {
|
||
self.truncate(0);
|
||
}
|
||
|
||
/// Remove and return the element at position `index`, shifting all elements after it to the
|
||
/// left.
|
||
///
|
||
/// Panics if `index` is out of bounds.
|
||
pub fn remove(&mut self, index: usize) -> A::Item {
|
||
unsafe {
|
||
let (mut ptr, len_ptr, _) = self.triple_mut();
|
||
let len = *len_ptr;
|
||
assert!(index < len);
|
||
*len_ptr = len - 1;
|
||
ptr = ptr.add(index);
|
||
let item = ptr::read(ptr);
|
||
ptr::copy(ptr.add(1), ptr, len - index - 1);
|
||
item
|
||
}
|
||
}
|
||
|
||
/// Insert an element at position `index`, shifting all elements after it to the right.
|
||
///
|
||
/// Panics if `index > len`.
|
||
pub fn insert(&mut self, index: usize, element: A::Item) {
|
||
self.reserve(1);
|
||
|
||
unsafe {
|
||
let (mut ptr, len_ptr, _) = self.triple_mut();
|
||
let len = *len_ptr;
|
||
ptr = ptr.add(index);
|
||
if index < len {
|
||
ptr::copy(ptr, ptr.add(1), len - index);
|
||
} else if index == len {
|
||
// No elements need shifting.
|
||
} else {
|
||
panic!("index exceeds length");
|
||
}
|
||
*len_ptr = len + 1;
|
||
ptr::write(ptr, element);
|
||
}
|
||
}
|
||
|
||
/// Insert multiple elements at position `index`, shifting all following elements toward the
|
||
/// back.
|
||
pub fn insert_many<I: IntoIterator<Item = A::Item>>(&mut self, index: usize, iterable: I) {
|
||
let mut iter = iterable.into_iter();
|
||
if index == self.len() {
|
||
return self.extend(iter);
|
||
}
|
||
|
||
let (lower_size_bound, _) = iter.size_hint();
|
||
assert!(lower_size_bound <= core::isize::MAX as usize); // Ensure offset is indexable
|
||
assert!(index + lower_size_bound >= index); // Protect against overflow
|
||
|
||
let mut num_added = 0;
|
||
let old_len = self.len();
|
||
assert!(index <= old_len);
|
||
|
||
unsafe {
|
||
// Reserve space for `lower_size_bound` elements.
|
||
self.reserve(lower_size_bound);
|
||
let start = self.as_mut_ptr();
|
||
let ptr = start.add(index);
|
||
|
||
// Move the trailing elements.
|
||
ptr::copy(ptr, ptr.add(lower_size_bound), old_len - index);
|
||
|
||
// In case the iterator panics, don't double-drop the items we just copied above.
|
||
self.set_len(0);
|
||
let mut guard = DropOnPanic {
|
||
start,
|
||
skip: index..(index + lower_size_bound),
|
||
len: old_len + lower_size_bound,
|
||
};
|
||
|
||
// The set_len above invalidates the previous pointers, so we must re-create them.
|
||
let start = self.as_mut_ptr();
|
||
let ptr = start.add(index);
|
||
|
||
while num_added < lower_size_bound {
|
||
let element = match iter.next() {
|
||
Some(x) => x,
|
||
None => break,
|
||
};
|
||
let cur = ptr.add(num_added);
|
||
ptr::write(cur, element);
|
||
guard.skip.start += 1;
|
||
num_added += 1;
|
||
}
|
||
|
||
if num_added < lower_size_bound {
|
||
// Iterator provided fewer elements than the hint. Move the tail backward.
|
||
ptr::copy(
|
||
ptr.add(lower_size_bound),
|
||
ptr.add(num_added),
|
||
old_len - index,
|
||
);
|
||
}
|
||
// There are no more duplicate or uninitialized slots, so the guard is not needed.
|
||
self.set_len(old_len + num_added);
|
||
mem::forget(guard);
|
||
}
|
||
|
||
// Insert any remaining elements one-by-one.
|
||
for element in iter {
|
||
self.insert(index + num_added, element);
|
||
num_added += 1;
|
||
}
|
||
|
||
struct DropOnPanic<T> {
|
||
start: *mut T,
|
||
skip: Range<usize>, // Space we copied-out-of, but haven't written-to yet.
|
||
len: usize,
|
||
}
|
||
|
||
impl<T> Drop for DropOnPanic<T> {
|
||
fn drop(&mut self) {
|
||
for i in 0..self.len {
|
||
if !self.skip.contains(&i) {
|
||
unsafe {
|
||
ptr::drop_in_place(self.start.add(i));
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Convert a SmallVec to a Vec, without reallocating if the SmallVec has already spilled onto
|
||
/// the heap.
|
||
pub fn into_vec(self) -> Vec<A::Item> {
|
||
if self.spilled() {
|
||
unsafe {
|
||
let (ptr, len) = self.data.heap();
|
||
let v = Vec::from_raw_parts(ptr, len, self.capacity);
|
||
mem::forget(self);
|
||
v
|
||
}
|
||
} else {
|
||
self.into_iter().collect()
|
||
}
|
||
}
|
||
|
||
/// Converts a `SmallVec` into a `Box<[T]>` without reallocating if the `SmallVec` has already spilled
|
||
/// onto the heap.
|
||
///
|
||
/// Note that this will drop any excess capacity.
|
||
pub fn into_boxed_slice(self) -> Box<[A::Item]> {
|
||
self.into_vec().into_boxed_slice()
|
||
}
|
||
|
||
/// Convert the SmallVec into an `A` if possible. Otherwise return `Err(Self)`.
|
||
///
|
||
/// This method returns `Err(Self)` if the SmallVec is too short (and the `A` contains uninitialized elements),
|
||
/// or if the SmallVec is too long (and all the elements were spilled to the heap).
|
||
pub fn into_inner(self) -> Result<A, Self> {
|
||
if self.spilled() || self.len() != A::size() {
|
||
// Note: A::size, not Self::inline_capacity
|
||
Err(self)
|
||
} else {
|
||
unsafe {
|
||
let data = ptr::read(&self.data);
|
||
mem::forget(self);
|
||
Ok(data.into_inline().assume_init())
|
||
}
|
||
}
|
||
}
|
||
|
||
/// 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.
|
||
pub fn retain<F: FnMut(&mut A::Item) -> bool>(&mut self, mut f: F) {
|
||
let mut del = 0;
|
||
let len = self.len();
|
||
for i in 0..len {
|
||
if !f(&mut self[i]) {
|
||
del += 1;
|
||
} else if del > 0 {
|
||
self.swap(i - del, i);
|
||
}
|
||
}
|
||
self.truncate(len - del);
|
||
}
|
||
|
||
/// Retains only the elements specified by the predicate.
|
||
///
|
||
/// This method is identical in behaviour to [`retain`]; it is included only
|
||
/// to maintain api-compatability with `std::Vec`, where the methods are
|
||
/// separate for historical reasons.
|
||
pub fn retain_mut<F: FnMut(&mut A::Item) -> bool>(&mut self, f: F) {
|
||
self.retain(f)
|
||
}
|
||
|
||
/// Removes consecutive duplicate elements.
|
||
pub fn dedup(&mut self)
|
||
where
|
||
A::Item: PartialEq<A::Item>,
|
||
{
|
||
self.dedup_by(|a, b| a == b);
|
||
}
|
||
|
||
/// Removes consecutive duplicate elements using the given equality relation.
|
||
pub fn dedup_by<F>(&mut self, mut same_bucket: F)
|
||
where
|
||
F: FnMut(&mut A::Item, &mut A::Item) -> bool,
|
||
{
|
||
// See the implementation of Vec::dedup_by in the
|
||
// standard library for an explanation of this algorithm.
|
||
let len = self.len();
|
||
if len <= 1 {
|
||
return;
|
||
}
|
||
|
||
let ptr = self.as_mut_ptr();
|
||
let mut w: usize = 1;
|
||
|
||
unsafe {
|
||
for r in 1..len {
|
||
let p_r = ptr.add(r);
|
||
let p_wm1 = ptr.add(w - 1);
|
||
if !same_bucket(&mut *p_r, &mut *p_wm1) {
|
||
if r != w {
|
||
let p_w = p_wm1.add(1);
|
||
mem::swap(&mut *p_r, &mut *p_w);
|
||
}
|
||
w += 1;
|
||
}
|
||
}
|
||
}
|
||
|
||
self.truncate(w);
|
||
}
|
||
|
||
/// Removes consecutive elements that map to the same key.
|
||
pub fn dedup_by_key<F, K>(&mut self, mut key: F)
|
||
where
|
||
F: FnMut(&mut A::Item) -> K,
|
||
K: PartialEq<K>,
|
||
{
|
||
self.dedup_by(|a, b| key(a) == key(b));
|
||
}
|
||
|
||
/// Resizes the `SmallVec` in-place so that `len` is equal to `new_len`.
|
||
///
|
||
/// If `new_len` is greater than `len`, the `SmallVec` is extended by the difference, with each
|
||
/// additional slot filled with the result of calling the closure `f`. The return values from `f`
|
||
//// will end up in the `SmallVec` in the order they have been generated.
|
||
///
|
||
/// If `new_len` is less than `len`, the `SmallVec` is simply truncated.
|
||
///
|
||
/// This method uses a closure to create new values on every push. If you'd rather `Clone` a given
|
||
/// value, use `resize`. If you want to use the `Default` trait to generate values, you can pass
|
||
/// `Default::default()` as the second argument.
|
||
///
|
||
/// Added for std::vec::Vec compatibility (added in Rust 1.33.0)
|
||
///
|
||
/// ```
|
||
/// # use smallvec::{smallvec, SmallVec};
|
||
/// let mut vec : SmallVec<[_; 4]> = smallvec![1, 2, 3];
|
||
/// vec.resize_with(5, Default::default);
|
||
/// assert_eq!(&*vec, &[1, 2, 3, 0, 0]);
|
||
///
|
||
/// let mut vec : SmallVec<[_; 4]> = smallvec![];
|
||
/// let mut p = 1;
|
||
/// vec.resize_with(4, || { p *= 2; p });
|
||
/// assert_eq!(&*vec, &[2, 4, 8, 16]);
|
||
/// ```
|
||
pub fn resize_with<F>(&mut self, new_len: usize, f: F)
|
||
where
|
||
F: FnMut() -> A::Item,
|
||
{
|
||
let old_len = self.len();
|
||
if old_len < new_len {
|
||
let mut f = f;
|
||
let additional = new_len - old_len;
|
||
self.reserve(additional);
|
||
for _ in 0..additional {
|
||
self.push(f());
|
||
}
|
||
} else if old_len > new_len {
|
||
self.truncate(new_len);
|
||
}
|
||
}
|
||
|
||
/// Creates a `SmallVec` directly from the raw components of another
|
||
/// `SmallVec`.
|
||
///
|
||
/// # Safety
|
||
///
|
||
/// This is highly unsafe, due to the number of invariants that aren't
|
||
/// checked:
|
||
///
|
||
/// * `ptr` needs to have been previously allocated via `SmallVec` for its
|
||
/// spilled storage (at least, it's highly likely to be incorrect if it
|
||
/// wasn't).
|
||
/// * `ptr`'s `A::Item` type needs to be the same size and alignment that
|
||
/// 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.
|
||
///
|
||
/// Additionally, `capacity` must be greater than the amount of inline
|
||
/// storage `A` has; that is, the new `SmallVec` must need to spill over
|
||
/// into heap allocated storage. This condition is asserted against.
|
||
///
|
||
/// The ownership of `ptr` is effectively transferred to the
|
||
/// `SmallVec` 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.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// # #[macro_use] extern crate smallvec;
|
||
/// # use smallvec::SmallVec;
|
||
/// use std::mem;
|
||
/// use std::ptr;
|
||
///
|
||
/// fn main() {
|
||
/// let mut v: SmallVec<[_; 1]> = smallvec![1, 2, 3];
|
||
///
|
||
/// // Pull out the important parts of `v`.
|
||
/// let p = v.as_mut_ptr();
|
||
/// let len = v.len();
|
||
/// let cap = v.capacity();
|
||
/// let spilled = v.spilled();
|
||
///
|
||
/// unsafe {
|
||
/// // Forget all about `v`. The heap allocation that stored the
|
||
/// // three values won't be deallocated.
|
||
/// mem::forget(v);
|
||
///
|
||
/// // Overwrite memory with [4, 5, 6].
|
||
/// //
|
||
/// // This is only safe if `spilled` is true! Otherwise, we are
|
||
/// // writing into the old `SmallVec`'s inline storage on the
|
||
/// // stack.
|
||
/// assert!(spilled);
|
||
/// for i in 0..len {
|
||
/// ptr::write(p.add(i), 4 + i);
|
||
/// }
|
||
///
|
||
/// // Put everything back together into a SmallVec with a different
|
||
/// // amount of inline storage, but which is still less than `cap`.
|
||
/// let rebuilt = SmallVec::<[_; 2]>::from_raw_parts(p, len, cap);
|
||
/// assert_eq!(&*rebuilt, &[4, 5, 6]);
|
||
/// }
|
||
/// }
|
||
#[inline]
|
||
pub unsafe fn from_raw_parts(ptr: *mut A::Item, length: usize, capacity: usize) -> SmallVec<A> {
|
||
assert!(capacity > Self::inline_capacity());
|
||
SmallVec {
|
||
capacity,
|
||
data: SmallVecData::from_heap(ptr, length),
|
||
}
|
||
}
|
||
|
||
/// Returns a raw pointer to the vector's buffer.
|
||
pub fn as_ptr(&self) -> *const A::Item {
|
||
// We shadow the slice method of the same name to avoid going through
|
||
// `deref`, which creates an intermediate reference that may place
|
||
// additional safety constraints on the contents of the slice.
|
||
self.triple().0
|
||
}
|
||
|
||
/// Returns a raw mutable pointer to the vector's buffer.
|
||
pub fn as_mut_ptr(&mut self) -> *mut A::Item {
|
||
// We shadow the slice method of the same name to avoid going through
|
||
// `deref_mut`, which creates an intermediate reference that may place
|
||
// additional safety constraints on the contents of the slice.
|
||
self.triple_mut().0
|
||
}
|
||
}
|
||
|
||
impl<A: Array> SmallVec<A>
|
||
where
|
||
A::Item: Copy,
|
||
{
|
||
/// Copy the elements from a slice into a new `SmallVec`.
|
||
///
|
||
/// For slices of `Copy` types, this is more efficient than `SmallVec::from(slice)`.
|
||
pub fn from_slice(slice: &[A::Item]) -> Self {
|
||
let len = slice.len();
|
||
if len <= Self::inline_capacity() {
|
||
SmallVec {
|
||
capacity: len,
|
||
data: SmallVecData::from_inline(unsafe {
|
||
let mut data: MaybeUninit<A> = MaybeUninit::uninit();
|
||
ptr::copy_nonoverlapping(
|
||
slice.as_ptr(),
|
||
data.as_mut_ptr() as *mut A::Item,
|
||
len,
|
||
);
|
||
data
|
||
}),
|
||
}
|
||
} else {
|
||
let mut b = slice.to_vec();
|
||
let (ptr, cap) = (b.as_mut_ptr(), b.capacity());
|
||
mem::forget(b);
|
||
SmallVec {
|
||
capacity: cap,
|
||
data: SmallVecData::from_heap(ptr, len),
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Copy elements from a slice into the vector at position `index`, shifting any following
|
||
/// elements toward the back.
|
||
///
|
||
/// For slices of `Copy` types, this is more efficient than `insert`.
|
||
pub fn insert_from_slice(&mut self, index: usize, slice: &[A::Item]) {
|
||
self.reserve(slice.len());
|
||
|
||
let len = self.len();
|
||
assert!(index <= len);
|
||
|
||
unsafe {
|
||
let slice_ptr = slice.as_ptr();
|
||
let ptr = self.as_mut_ptr().add(index);
|
||
ptr::copy(ptr, ptr.add(slice.len()), len - index);
|
||
ptr::copy_nonoverlapping(slice_ptr, ptr, slice.len());
|
||
self.set_len(len + slice.len());
|
||
}
|
||
}
|
||
|
||
/// Copy elements from a slice and append them to the vector.
|
||
///
|
||
/// For slices of `Copy` types, this is more efficient than `extend`.
|
||
#[inline]
|
||
pub fn extend_from_slice(&mut self, slice: &[A::Item]) {
|
||
let len = self.len();
|
||
self.insert_from_slice(len, slice);
|
||
}
|
||
}
|
||
|
||
impl<A: Array> SmallVec<A>
|
||
where
|
||
A::Item: Clone,
|
||
{
|
||
/// Resizes the vector so that its length is equal to `len`.
|
||
///
|
||
/// If `len` is less than the current length, the vector simply truncated.
|
||
///
|
||
/// If `len` is greater than the current length, `value` is appended to the
|
||
/// vector until its length equals `len`.
|
||
pub fn resize(&mut self, len: usize, value: A::Item) {
|
||
let old_len = self.len();
|
||
|
||
if len > old_len {
|
||
self.extend(repeat(value).take(len - old_len));
|
||
} else {
|
||
self.truncate(len);
|
||
}
|
||
}
|
||
|
||
/// Creates a `SmallVec` with `n` copies of `elem`.
|
||
/// ```
|
||
/// use smallvec::SmallVec;
|
||
///
|
||
/// let v = SmallVec::<[char; 128]>::from_elem('d', 2);
|
||
/// assert_eq!(v, SmallVec::from_buf(['d', 'd']));
|
||
/// ```
|
||
pub fn from_elem(elem: A::Item, n: usize) -> Self {
|
||
if n > Self::inline_capacity() {
|
||
vec![elem; n].into()
|
||
} else {
|
||
let mut v = SmallVec::<A>::new();
|
||
unsafe {
|
||
let (ptr, len_ptr, _) = v.triple_mut();
|
||
let mut local_len = SetLenOnDrop::new(len_ptr);
|
||
|
||
for i in 0..n {
|
||
::core::ptr::write(ptr.add(i), elem.clone());
|
||
local_len.increment_len(1);
|
||
}
|
||
}
|
||
v
|
||
}
|
||
}
|
||
}
|
||
|
||
impl<A: Array> ops::Deref for SmallVec<A> {
|
||
type Target = [A::Item];
|
||
#[inline]
|
||
fn deref(&self) -> &[A::Item] {
|
||
unsafe {
|
||
let (ptr, len, _) = self.triple();
|
||
slice::from_raw_parts(ptr, len)
|
||
}
|
||
}
|
||
}
|
||
|
||
impl<A: Array> ops::DerefMut for SmallVec<A> {
|
||
#[inline]
|
||
fn deref_mut(&mut self) -> &mut [A::Item] {
|
||
unsafe {
|
||
let (ptr, &mut len, _) = self.triple_mut();
|
||
slice::from_raw_parts_mut(ptr, len)
|
||
}
|
||
}
|
||
}
|
||
|
||
impl<A: Array> AsRef<[A::Item]> for SmallVec<A> {
|
||
#[inline]
|
||
fn as_ref(&self) -> &[A::Item] {
|
||
self
|
||
}
|
||
}
|
||
|
||
impl<A: Array> AsMut<[A::Item]> for SmallVec<A> {
|
||
#[inline]
|
||
fn as_mut(&mut self) -> &mut [A::Item] {
|
||
self
|
||
}
|
||
}
|
||
|
||
impl<A: Array> Borrow<[A::Item]> for SmallVec<A> {
|
||
#[inline]
|
||
fn borrow(&self) -> &[A::Item] {
|
||
self
|
||
}
|
||
}
|
||
|
||
impl<A: Array> BorrowMut<[A::Item]> for SmallVec<A> {
|
||
#[inline]
|
||
fn borrow_mut(&mut self) -> &mut [A::Item] {
|
||
self
|
||
}
|
||
}
|
||
|
||
#[cfg(feature = "write")]
|
||
#[cfg_attr(docsrs, doc(cfg(feature = "write")))]
|
||
impl<A: Array<Item = u8>> io::Write for SmallVec<A> {
|
||
#[inline]
|
||
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
|
||
self.extend_from_slice(buf);
|
||
Ok(buf.len())
|
||
}
|
||
|
||
#[inline]
|
||
fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
|
||
self.extend_from_slice(buf);
|
||
Ok(())
|
||
}
|
||
|
||
#[inline]
|
||
fn flush(&mut self) -> io::Result<()> {
|
||
Ok(())
|
||
}
|
||
}
|
||
|
||
#[cfg(feature = "serde")]
|
||
#[cfg_attr(docsrs, doc(cfg(feature = "serde")))]
|
||
impl<A: Array> Serialize for SmallVec<A>
|
||
where
|
||
A::Item: Serialize,
|
||
{
|
||
fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
|
||
let mut state = serializer.serialize_seq(Some(self.len()))?;
|
||
for item in self {
|
||
state.serialize_element(&item)?;
|
||
}
|
||
state.end()
|
||
}
|
||
}
|
||
|
||
#[cfg(feature = "serde")]
|
||
#[cfg_attr(docsrs, doc(cfg(feature = "serde")))]
|
||
impl<'de, A: Array> Deserialize<'de> for SmallVec<A>
|
||
where
|
||
A::Item: Deserialize<'de>,
|
||
{
|
||
fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
|
||
deserializer.deserialize_seq(SmallVecVisitor {
|
||
phantom: PhantomData,
|
||
})
|
||
}
|
||
}
|
||
|
||
#[cfg(feature = "serde")]
|
||
struct SmallVecVisitor<A> {
|
||
phantom: PhantomData<A>,
|
||
}
|
||
|
||
#[cfg(feature = "serde")]
|
||
impl<'de, A: Array> Visitor<'de> for SmallVecVisitor<A>
|
||
where
|
||
A::Item: Deserialize<'de>,
|
||
{
|
||
type Value = SmallVec<A>;
|
||
|
||
fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
formatter.write_str("a sequence")
|
||
}
|
||
|
||
fn visit_seq<B>(self, mut seq: B) -> Result<Self::Value, B::Error>
|
||
where
|
||
B: SeqAccess<'de>,
|
||
{
|
||
use serde::de::Error;
|
||
let len = seq.size_hint().unwrap_or(0);
|
||
let mut values = SmallVec::new();
|
||
values.try_reserve(len).map_err(B::Error::custom)?;
|
||
|
||
while let Some(value) = seq.next_element()? {
|
||
values.push(value);
|
||
}
|
||
|
||
Ok(values)
|
||
}
|
||
}
|
||
|
||
#[cfg(feature = "specialization")]
|
||
trait SpecFrom<A: Array, S> {
|
||
fn spec_from(slice: S) -> SmallVec<A>;
|
||
}
|
||
|
||
#[cfg(feature = "specialization")]
|
||
mod specialization;
|
||
|
||
#[cfg(feature = "arbitrary")]
|
||
mod arbitrary;
|
||
|
||
#[cfg(feature = "specialization")]
|
||
impl<'a, A: Array> SpecFrom<A, &'a [A::Item]> for SmallVec<A>
|
||
where
|
||
A::Item: Copy,
|
||
{
|
||
#[inline]
|
||
fn spec_from(slice: &'a [A::Item]) -> SmallVec<A> {
|
||
SmallVec::from_slice(slice)
|
||
}
|
||
}
|
||
|
||
impl<'a, A: Array> From<&'a [A::Item]> for SmallVec<A>
|
||
where
|
||
A::Item: Clone,
|
||
{
|
||
#[cfg(not(feature = "specialization"))]
|
||
#[inline]
|
||
fn from(slice: &'a [A::Item]) -> SmallVec<A> {
|
||
slice.iter().cloned().collect()
|
||
}
|
||
|
||
#[cfg(feature = "specialization")]
|
||
#[inline]
|
||
fn from(slice: &'a [A::Item]) -> SmallVec<A> {
|
||
SmallVec::spec_from(slice)
|
||
}
|
||
}
|
||
|
||
impl<A: Array> From<Vec<A::Item>> for SmallVec<A> {
|
||
#[inline]
|
||
fn from(vec: Vec<A::Item>) -> SmallVec<A> {
|
||
SmallVec::from_vec(vec)
|
||
}
|
||
}
|
||
|
||
impl<A: Array> From<A> for SmallVec<A> {
|
||
#[inline]
|
||
fn from(array: A) -> SmallVec<A> {
|
||
SmallVec::from_buf(array)
|
||
}
|
||
}
|
||
|
||
impl<A: Array, I: SliceIndex<[A::Item]>> ops::Index<I> for SmallVec<A> {
|
||
type Output = I::Output;
|
||
|
||
fn index(&self, index: I) -> &I::Output {
|
||
&(**self)[index]
|
||
}
|
||
}
|
||
|
||
impl<A: Array, I: SliceIndex<[A::Item]>> ops::IndexMut<I> for SmallVec<A> {
|
||
fn index_mut(&mut self, index: I) -> &mut I::Output {
|
||
&mut (&mut **self)[index]
|
||
}
|
||
}
|
||
|
||
#[allow(deprecated)]
|
||
impl<A: Array> ExtendFromSlice<A::Item> for SmallVec<A>
|
||
where
|
||
A::Item: Copy,
|
||
{
|
||
fn extend_from_slice(&mut self, other: &[A::Item]) {
|
||
SmallVec::extend_from_slice(self, other)
|
||
}
|
||
}
|
||
|
||
impl<A: Array> FromIterator<A::Item> for SmallVec<A> {
|
||
#[inline]
|
||
fn from_iter<I: IntoIterator<Item = A::Item>>(iterable: I) -> SmallVec<A> {
|
||
let mut v = SmallVec::new();
|
||
v.extend(iterable);
|
||
v
|
||
}
|
||
}
|
||
|
||
impl<A: Array> Extend<A::Item> for SmallVec<A> {
|
||
fn extend<I: IntoIterator<Item = A::Item>>(&mut self, iterable: I) {
|
||
let mut iter = iterable.into_iter();
|
||
let (lower_size_bound, _) = iter.size_hint();
|
||
self.reserve(lower_size_bound);
|
||
|
||
unsafe {
|
||
let (ptr, len_ptr, cap) = self.triple_mut();
|
||
let mut len = SetLenOnDrop::new(len_ptr);
|
||
while len.get() < cap {
|
||
if let Some(out) = iter.next() {
|
||
ptr::write(ptr.add(len.get()), out);
|
||
len.increment_len(1);
|
||
} else {
|
||
return;
|
||
}
|
||
}
|
||
}
|
||
|
||
for elem in iter {
|
||
self.push(elem);
|
||
}
|
||
}
|
||
}
|
||
|
||
impl<A: Array> fmt::Debug for SmallVec<A>
|
||
where
|
||
A::Item: fmt::Debug,
|
||
{
|
||
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
f.debug_list().entries(self.iter()).finish()
|
||
}
|
||
}
|
||
|
||
impl<A: Array> Default for SmallVec<A> {
|
||
#[inline]
|
||
fn default() -> SmallVec<A> {
|
||
SmallVec::new()
|
||
}
|
||
}
|
||
|
||
#[cfg(feature = "may_dangle")]
|
||
unsafe impl<#[may_dangle] A: Array> Drop for SmallVec<A> {
|
||
fn drop(&mut self) {
|
||
unsafe {
|
||
if self.spilled() {
|
||
let (ptr, len) = self.data.heap();
|
||
Vec::from_raw_parts(ptr, len, self.capacity);
|
||
} else {
|
||
ptr::drop_in_place(&mut self[..]);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
#[cfg(not(feature = "may_dangle"))]
|
||
impl<A: Array> Drop for SmallVec<A> {
|
||
fn drop(&mut self) {
|
||
unsafe {
|
||
if self.spilled() {
|
||
let (ptr, len) = self.data.heap();
|
||
Vec::from_raw_parts(ptr, len, self.capacity);
|
||
} else {
|
||
ptr::drop_in_place(&mut self[..]);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
impl<A: Array> Clone for SmallVec<A>
|
||
where
|
||
A::Item: Clone,
|
||
{
|
||
#[inline]
|
||
fn clone(&self) -> SmallVec<A> {
|
||
SmallVec::from(self.as_slice())
|
||
}
|
||
|
||
fn clone_from(&mut self, source: &Self) {
|
||
// Inspired from `impl Clone for Vec`.
|
||
|
||
// drop anything that will not be overwritten
|
||
self.truncate(source.len());
|
||
|
||
// self.len <= other.len due to the truncate above, so the
|
||
// slices here are always in-bounds.
|
||
let (init, tail) = source.split_at(self.len());
|
||
|
||
// reuse the contained values' allocations/resources.
|
||
self.clone_from_slice(init);
|
||
self.extend(tail.iter().cloned());
|
||
}
|
||
}
|
||
|
||
impl<A: Array, B: Array> PartialEq<SmallVec<B>> for SmallVec<A>
|
||
where
|
||
A::Item: PartialEq<B::Item>,
|
||
{
|
||
#[inline]
|
||
fn eq(&self, other: &SmallVec<B>) -> bool {
|
||
self[..] == other[..]
|
||
}
|
||
}
|
||
|
||
impl<A: Array> Eq for SmallVec<A> where A::Item: Eq {}
|
||
|
||
impl<A: Array> PartialOrd for SmallVec<A>
|
||
where
|
||
A::Item: PartialOrd,
|
||
{
|
||
#[inline]
|
||
fn partial_cmp(&self, other: &SmallVec<A>) -> Option<cmp::Ordering> {
|
||
PartialOrd::partial_cmp(&**self, &**other)
|
||
}
|
||
}
|
||
|
||
impl<A: Array> Ord for SmallVec<A>
|
||
where
|
||
A::Item: Ord,
|
||
{
|
||
#[inline]
|
||
fn cmp(&self, other: &SmallVec<A>) -> cmp::Ordering {
|
||
Ord::cmp(&**self, &**other)
|
||
}
|
||
}
|
||
|
||
impl<A: Array> Hash for SmallVec<A>
|
||
where
|
||
A::Item: Hash,
|
||
{
|
||
fn hash<H: Hasher>(&self, state: &mut H) {
|
||
(**self).hash(state)
|
||
}
|
||
}
|
||
|
||
unsafe impl<A: Array> Send for SmallVec<A> where A::Item: Send {}
|
||
|
||
/// An iterator that consumes a `SmallVec` and yields its items by value.
|
||
///
|
||
/// Returned from [`SmallVec::into_iter`][1].
|
||
///
|
||
/// [1]: struct.SmallVec.html#method.into_iter
|
||
pub struct IntoIter<A: Array> {
|
||
data: SmallVec<A>,
|
||
current: usize,
|
||
end: usize,
|
||
}
|
||
|
||
impl<A: Array> fmt::Debug for IntoIter<A>
|
||
where
|
||
A::Item: fmt::Debug,
|
||
{
|
||
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
f.debug_tuple("IntoIter").field(&self.as_slice()).finish()
|
||
}
|
||
}
|
||
|
||
impl<A: Array + Clone> Clone for IntoIter<A>
|
||
where
|
||
A::Item: Clone,
|
||
{
|
||
fn clone(&self) -> IntoIter<A> {
|
||
SmallVec::from(self.as_slice()).into_iter()
|
||
}
|
||
}
|
||
|
||
impl<A: Array> Drop for IntoIter<A> {
|
||
fn drop(&mut self) {
|
||
for _ in self {}
|
||
}
|
||
}
|
||
|
||
impl<A: Array> Iterator for IntoIter<A> {
|
||
type Item = A::Item;
|
||
|
||
#[inline]
|
||
fn next(&mut self) -> Option<A::Item> {
|
||
if self.current == self.end {
|
||
None
|
||
} else {
|
||
unsafe {
|
||
let current = self.current;
|
||
self.current += 1;
|
||
Some(ptr::read(self.data.as_ptr().add(current)))
|
||
}
|
||
}
|
||
}
|
||
|
||
#[inline]
|
||
fn size_hint(&self) -> (usize, Option<usize>) {
|
||
let size = self.end - self.current;
|
||
(size, Some(size))
|
||
}
|
||
}
|
||
|
||
impl<A: Array> DoubleEndedIterator for IntoIter<A> {
|
||
#[inline]
|
||
fn next_back(&mut self) -> Option<A::Item> {
|
||
if self.current == self.end {
|
||
None
|
||
} else {
|
||
unsafe {
|
||
self.end -= 1;
|
||
Some(ptr::read(self.data.as_ptr().add(self.end)))
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
impl<A: Array> ExactSizeIterator for IntoIter<A> {}
|
||
impl<A: Array> FusedIterator for IntoIter<A> {}
|
||
|
||
impl<A: Array> IntoIter<A> {
|
||
/// Returns the remaining items of this iterator as a slice.
|
||
pub fn as_slice(&self) -> &[A::Item] {
|
||
let len = self.end - self.current;
|
||
unsafe { core::slice::from_raw_parts(self.data.as_ptr().add(self.current), len) }
|
||
}
|
||
|
||
/// Returns the remaining items of this iterator as a mutable slice.
|
||
pub fn as_mut_slice(&mut self) -> &mut [A::Item] {
|
||
let len = self.end - self.current;
|
||
unsafe { core::slice::from_raw_parts_mut(self.data.as_mut_ptr().add(self.current), len) }
|
||
}
|
||
}
|
||
|
||
impl<A: Array> IntoIterator for SmallVec<A> {
|
||
type IntoIter = IntoIter<A>;
|
||
type Item = A::Item;
|
||
fn into_iter(mut self) -> Self::IntoIter {
|
||
unsafe {
|
||
// Set SmallVec len to zero as `IntoIter` drop handles dropping of the elements
|
||
let len = self.len();
|
||
self.set_len(0);
|
||
IntoIter {
|
||
data: self,
|
||
current: 0,
|
||
end: len,
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
impl<'a, A: Array> IntoIterator for &'a SmallVec<A> {
|
||
type IntoIter = slice::Iter<'a, A::Item>;
|
||
type Item = &'a A::Item;
|
||
fn into_iter(self) -> Self::IntoIter {
|
||
self.iter()
|
||
}
|
||
}
|
||
|
||
impl<'a, A: Array> IntoIterator for &'a mut SmallVec<A> {
|
||
type IntoIter = slice::IterMut<'a, A::Item>;
|
||
type Item = &'a mut A::Item;
|
||
fn into_iter(self) -> Self::IntoIter {
|
||
self.iter_mut()
|
||
}
|
||
}
|
||
|
||
/// Types that can be used as the backing store for a SmallVec
|
||
pub unsafe trait Array {
|
||
/// The type of the array's elements.
|
||
type Item;
|
||
/// Returns the number of items the array can hold.
|
||
fn size() -> usize;
|
||
}
|
||
|
||
/// Set the length of the vec when the `SetLenOnDrop` value goes out of scope.
|
||
///
|
||
/// Copied from https://github.com/rust-lang/rust/pull/36355
|
||
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 get(&self) -> usize {
|
||
self.local_len
|
||
}
|
||
|
||
#[inline]
|
||
fn increment_len(&mut self, increment: usize) {
|
||
self.local_len += increment;
|
||
}
|
||
}
|
||
|
||
impl<'a> Drop for SetLenOnDrop<'a> {
|
||
#[inline]
|
||
fn drop(&mut self) {
|
||
*self.len = self.local_len;
|
||
}
|
||
}
|
||
|
||
#[cfg(feature = "const_new")]
|
||
impl<T, const N: usize> SmallVec<[T; N]> {
|
||
/// Construct an empty vector.
|
||
///
|
||
/// This is a `const` version of [`SmallVec::new`] that is enabled by the feature `const_new`, with the limitation that it only works for arrays.
|
||
#[cfg_attr(docsrs, doc(cfg(feature = "const_new")))]
|
||
#[inline]
|
||
pub const fn new_const() -> Self {
|
||
SmallVec {
|
||
capacity: 0,
|
||
data: SmallVecData::from_const(MaybeUninit::uninit()),
|
||
}
|
||
}
|
||
|
||
/// The array passed as an argument is moved to be an inline version of `SmallVec`.
|
||
///
|
||
/// This is a `const` version of [`SmallVec::from_buf`] that is enabled by the feature `const_new`, with the limitation that it only works for arrays.
|
||
#[cfg_attr(docsrs, doc(cfg(feature = "const_new")))]
|
||
#[inline]
|
||
pub const fn from_const(items: [T; N]) -> Self {
|
||
SmallVec {
|
||
capacity: N,
|
||
data: SmallVecData::from_const(MaybeUninit::new(items)),
|
||
}
|
||
}
|
||
}
|
||
|
||
#[cfg(all(feature = "const_generics", not(doc)))]
|
||
#[cfg_attr(docsrs, doc(cfg(feature = "const_generics")))]
|
||
unsafe impl<T, const N: usize> Array for [T; N] {
|
||
type Item = T;
|
||
#[inline]
|
||
fn size() -> usize {
|
||
N
|
||
}
|
||
}
|
||
|
||
#[cfg(any(not(feature = "const_generics"), doc))]
|
||
macro_rules! impl_array(
|
||
($($size:expr),+) => {
|
||
$(
|
||
unsafe impl<T> Array for [T; $size] {
|
||
type Item = T;
|
||
#[inline]
|
||
fn size() -> usize { $size }
|
||
}
|
||
)+
|
||
}
|
||
);
|
||
|
||
#[cfg(any(not(feature = "const_generics"), doc))]
|
||
impl_array!(
|
||
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,
|
||
26, 27, 28, 29, 30, 31, 32, 36, 0x40, 0x60, 0x80, 0x100, 0x200, 0x400, 0x600, 0x800, 0x1000,
|
||
0x2000, 0x4000, 0x6000, 0x8000, 0x10000, 0x20000, 0x40000, 0x60000, 0x80000, 0x10_0000
|
||
);
|
||
|
||
/// Convenience trait for constructing a `SmallVec`
|
||
pub trait ToSmallVec<A: Array> {
|
||
/// Construct a new `SmallVec` from a slice.
|
||
fn to_smallvec(&self) -> SmallVec<A>;
|
||
}
|
||
|
||
impl<A: Array> ToSmallVec<A> for [A::Item]
|
||
where
|
||
A::Item: Copy,
|
||
{
|
||
#[inline]
|
||
fn to_smallvec(&self) -> SmallVec<A> {
|
||
SmallVec::from_slice(self)
|
||
}
|
||
}
|