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// Copyright 2012-2017 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.
//! Slice management and manipulation
//!
//! For more details see [`std::slice`].
//!
//! [`std::slice`]: ../../std/slice/index.html
#![stable(feature = "rust1", since = "1.0.0")]
// How this module is organized.
//
// The library infrastructure for slices is fairly messy. There's
// a lot of stuff defined here. Let's keep it clean.
//
// Since slices don't support inherent methods; all operations
// on them are defined on traits, which are then re-exported from
// the prelude for convenience. So there are a lot of traits here.
//
// The layout of this file is thus:
//
// * Slice-specific 'extension' traits and their implementations. This
// is where most of the slice API resides.
// * Implementations of a few common traits with important slice ops.
// * Definitions of a bunch of iterators.
// * Free functions.
// * The `raw` and `bytes` submodules.
// * Boilerplate trait implementations.
use cmp::Ordering::{self, Less, Equal, Greater};
use cmp;
use fmt;
use intrinsics::assume;
use iter::*;
use ops::{FnMut, Try, self};
use option::Option;
use option::Option::{None, Some};
use result::Result;
use result::Result::{Ok, Err};
use ptr;
use mem;
use marker::{Copy, Send, Sync, Sized, self};
use iter_private::TrustedRandomAccess;
#[unstable(feature = "slice_internals", issue = "0",
reason = "exposed from core to be reused in std; use the memchr crate")]
/// Pure rust memchr implementation, taken from rust-memchr
pub mod memchr;
mod rotate;
mod sort;
#[repr(C)]
union Repr<'a, T: 'a> {
rust: &'a [T],
rust_mut: &'a mut [T],
raw: FatPtr<T>,
}
#[repr(C)]
struct FatPtr<T> {
data: *const T,
len: usize,
}
//
// Extension traits
//
// Use macros to be generic over const/mut
macro_rules! slice_offset {
($ptr:expr, $by:expr) => {{
let ptr = $ptr;
if size_from_ptr(ptr) == 0 {
(ptr as *mut i8).wrapping_offset($by) as _
} else {
ptr.offset($by)
}
}};
}
// make a &T from a *const T
macro_rules! make_ref {
($ptr:expr) => {{
let ptr = $ptr;
if size_from_ptr(ptr) == 0 {
// Use a non-null pointer value
&*(1 as *mut _)
} else {
&*ptr
}
}};
}
// make a &mut T from a *mut T
macro_rules! make_ref_mut {
($ptr:expr) => {{
let ptr = $ptr;
if size_from_ptr(ptr) == 0 {
// Use a non-null pointer value
&mut *(1 as *mut _)
} else {
&mut *ptr
}
}};
}
#[lang = "slice"]
#[cfg(not(test))]
impl<T> [T] {
/// Returns the number of elements in the slice.
///
/// # Examples
///
/// ```
/// let a = [1, 2, 3];
/// assert_eq!(a.len(), 3);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
#[rustc_const_unstable(feature = "const_slice_len")]
pub const fn len(&self) -> usize {
unsafe {
Repr { rust: self }.raw.len
}
}
/// Returns `true` if the slice has a length of 0.
///
/// # Examples
///
/// ```
/// let a = [1, 2, 3];
/// assert!(!a.is_empty());
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
#[rustc_const_unstable(feature = "const_slice_len")]
pub const fn is_empty(&self) -> bool {
self.len() == 0
}
/// Returns the first element of the slice, or `None` if it is empty.
///
/// # Examples
///
/// ```
/// let v = [10, 40, 30];
/// assert_eq!(Some(&10), v.first());
///
/// let w: &[i32] = &[];
/// assert_eq!(None, w.first());
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn first(&self) -> Option<&T> {
if self.is_empty() { None } else { Some(&self[0]) }
}
/// Returns a mutable pointer to the first element of the slice, or `None` if it is empty.
///
/// # Examples
///
/// ```
/// let x = &mut [0, 1, 2];
///
/// if let Some(first) = x.first_mut() {
/// *first = 5;
/// }
/// assert_eq!(x, &[5, 1, 2]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn first_mut(&mut self) -> Option<&mut T> {
if self.is_empty() { None } else { Some(&mut self[0]) }
}
/// Returns the first and all the rest of the elements of the slice, or `None` if it is empty.
///
/// # Examples
///
/// ```
/// let x = &[0, 1, 2];
///
/// if let Some((first, elements)) = x.split_first() {
/// assert_eq!(first, &0);
/// assert_eq!(elements, &[1, 2]);
/// }
/// ```
#[stable(feature = "slice_splits", since = "1.5.0")]
#[inline]
pub fn split_first(&self) -> Option<(&T, &[T])> {
if self.is_empty() { None } else { Some((&self[0], &self[1..])) }
}
/// Returns the first and all the rest of the elements of the slice, or `None` if it is empty.
///
/// # Examples
///
/// ```
/// let x = &mut [0, 1, 2];
///
/// if let Some((first, elements)) = x.split_first_mut() {
/// *first = 3;
/// elements[0] = 4;
/// elements[1] = 5;
/// }
/// assert_eq!(x, &[3, 4, 5]);
/// ```
#[stable(feature = "slice_splits", since = "1.5.0")]
#[inline]
pub fn split_first_mut(&mut self) -> Option<(&mut T, &mut [T])> {
if self.is_empty() { None } else {
let split = self.split_at_mut(1);
Some((&mut split.0[0], split.1))
}
}
/// Returns the last and all the rest of the elements of the slice, or `None` if it is empty.
///
/// # Examples
///
/// ```
/// let x = &[0, 1, 2];
///
/// if let Some((last, elements)) = x.split_last() {
/// assert_eq!(last, &2);
/// assert_eq!(elements, &[0, 1]);
/// }
/// ```
#[stable(feature = "slice_splits", since = "1.5.0")]
#[inline]
pub fn split_last(&self) -> Option<(&T, &[T])> {
let len = self.len();
if len == 0 { None } else { Some((&self[len - 1], &self[..(len - 1)])) }
}
/// Returns the last and all the rest of the elements of the slice, or `None` if it is empty.
///
/// # Examples
///
/// ```
/// let x = &mut [0, 1, 2];
///
/// if let Some((last, elements)) = x.split_last_mut() {
/// *last = 3;
/// elements[0] = 4;
/// elements[1] = 5;
/// }
/// assert_eq!(x, &[4, 5, 3]);
/// ```
#[stable(feature = "slice_splits", since = "1.5.0")]
#[inline]
pub fn split_last_mut(&mut self) -> Option<(&mut T, &mut [T])> {
let len = self.len();
if len == 0 { None } else {
let split = self.split_at_mut(len - 1);
Some((&mut split.1[0], split.0))
}
}
/// Returns the last element of the slice, or `None` if it is empty.
///
/// # Examples
///
/// ```
/// let v = [10, 40, 30];
/// assert_eq!(Some(&30), v.last());
///
/// let w: &[i32] = &[];
/// assert_eq!(None, w.last());
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn last(&self) -> Option<&T> {
if self.is_empty() { None } else { Some(&self[self.len() - 1]) }
}
/// Returns a mutable pointer to the last item in the slice.
///
/// # Examples
///
/// ```
/// let x = &mut [0, 1, 2];
///
/// if let Some(last) = x.last_mut() {
/// *last = 10;
/// }
/// assert_eq!(x, &[0, 1, 10]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn last_mut(&mut self) -> Option<&mut T> {
let len = self.len();
if len == 0 { return None; }
Some(&mut self[len - 1])
}
/// Returns a reference to an element or subslice depending on the type of
/// index.
///
/// - If given a position, returns a reference to the element at that
/// position or `None` if out of bounds.
/// - If given a range, returns the subslice corresponding to that range,
/// or `None` if out of bounds.
///
/// # Examples
///
/// ```
/// let v = [10, 40, 30];
/// assert_eq!(Some(&40), v.get(1));
/// assert_eq!(Some(&[10, 40][..]), v.get(0..2));
/// assert_eq!(None, v.get(3));
/// assert_eq!(None, v.get(0..4));
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn get<I>(&self, index: I) -> Option<&I::Output>
where I: SliceIndex<Self>
{
index.get(self)
}
/// Returns a mutable reference to an element or subslice depending on the
/// type of index (see [`get`]) or `None` if the index is out of bounds.
///
/// [`get`]: #method.get
///
/// # Examples
///
/// ```
/// let x = &mut [0, 1, 2];
///
/// if let Some(elem) = x.get_mut(1) {
/// *elem = 42;
/// }
/// assert_eq!(x, &[0, 42, 2]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn get_mut<I>(&mut self, index: I) -> Option<&mut I::Output>
where I: SliceIndex<Self>
{
index.get_mut(self)
}
/// Returns a reference to an element or subslice, without doing bounds
/// checking.
///
/// This is generally not recommended, use with caution! For a safe
/// alternative see [`get`].
///
/// [`get`]: #method.get
///
/// # Examples
///
/// ```
/// let x = &[1, 2, 4];
///
/// unsafe {
/// assert_eq!(x.get_unchecked(1), &2);
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub unsafe fn get_unchecked<I>(&self, index: I) -> &I::Output
where I: SliceIndex<Self>
{
index.get_unchecked(self)
}
/// Returns a mutable reference to an element or subslice, without doing
/// bounds checking.
///
/// This is generally not recommended, use with caution! For a safe
/// alternative see [`get_mut`].
///
/// [`get_mut`]: #method.get_mut
///
/// # Examples
///
/// ```
/// let x = &mut [1, 2, 4];
///
/// unsafe {
/// let elem = x.get_unchecked_mut(1);
/// *elem = 13;
/// }
/// assert_eq!(x, &[1, 13, 4]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub unsafe fn get_unchecked_mut<I>(&mut self, index: I) -> &mut I::Output
where I: SliceIndex<Self>
{
index.get_unchecked_mut(self)
}
/// Returns a raw pointer to the slice's buffer.
///
/// The caller must ensure that the slice outlives the pointer this
/// function returns, or else it will end up pointing to garbage.
///
/// Modifying the container referenced by this slice may cause its buffer
/// to be reallocated, which would also make any pointers to it invalid.
///
/// # Examples
///
/// ```
/// let x = &[1, 2, 4];
/// let x_ptr = x.as_ptr();
///
/// unsafe {
/// for i in 0..x.len() {
/// assert_eq!(x.get_unchecked(i), &*x_ptr.offset(i as isize));
/// }
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
#[rustc_const_unstable(feature = "const_slice_as_ptr")]
pub const fn as_ptr(&self) -> *const T {
self as *const [T] as *const T
}
/// Returns an unsafe mutable pointer to the slice's buffer.
///
/// The caller must ensure that the slice outlives the pointer this
/// function returns, or else it will end up pointing to garbage.
///
/// Modifying the container referenced by this slice may cause its buffer
/// to be reallocated, which would also make any pointers to it invalid.
///
/// # Examples
///
/// ```
/// let x = &mut [1, 2, 4];
/// let x_ptr = x.as_mut_ptr();
///
/// unsafe {
/// for i in 0..x.len() {
/// *x_ptr.offset(i as isize) += 2;
/// }
/// }
/// assert_eq!(x, &[3, 4, 6]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn as_mut_ptr(&mut self) -> *mut T {
self as *mut [T] as *mut T
}
/// Swaps two elements in the slice.
///
/// # Arguments
///
/// * a - The index of the first element
/// * b - The index of the second element
///
/// # Panics
///
/// Panics if `a` or `b` are out of bounds.
///
/// # Examples
///
/// ```
/// let mut v = ["a", "b", "c", "d"];
/// v.swap(1, 3);
/// assert!(v == ["a", "d", "c", "b"]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn swap(&mut self, a: usize, b: usize) {
unsafe {
// Can't take two mutable loans from one vector, so instead just cast
// them to their raw pointers to do the swap
let pa: *mut T = &mut self[a];
let pb: *mut T = &mut self[b];
ptr::swap(pa, pb);
}
}
/// Reverses the order of elements in the slice, in place.
///
/// # Examples
///
/// ```
/// let mut v = [1, 2, 3];
/// v.reverse();
/// assert!(v == [3, 2, 1]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn reverse(&mut self) {
let mut i: usize = 0;
let ln = self.len();
// For very small types, all the individual reads in the normal
// path perform poorly. We can do better, given efficient unaligned
// load/store, by loading a larger chunk and reversing a register.
// Ideally LLVM would do this for us, as it knows better than we do
// whether unaligned reads are efficient (since that changes between
// different ARM versions, for example) and what the best chunk size
// would be. Unfortunately, as of LLVM 4.0 (2017-05) it only unrolls
// the loop, so we need to do this ourselves. (Hypothesis: reverse
// is troublesome because the sides can be aligned differently --
// will be, when the length is odd -- so there's no way of emitting
// pre- and postludes to use fully-aligned SIMD in the middle.)
let fast_unaligned =
cfg!(any(target_arch = "x86", target_arch = "x86_64"));
if fast_unaligned && mem::size_of::<T>() == 1 {
// Use the llvm.bswap intrinsic to reverse u8s in a usize
let chunk = mem::size_of::<usize>();
while i + chunk - 1 < ln / 2 {
unsafe {
let pa: *mut T = self.get_unchecked_mut(i);
let pb: *mut T = self.get_unchecked_mut(ln - i - chunk);
let va = ptr::read_unaligned(pa as *mut usize);
let vb = ptr::read_unaligned(pb as *mut usize);
ptr::write_unaligned(pa as *mut usize, vb.swap_bytes());
ptr::write_unaligned(pb as *mut usize, va.swap_bytes());
}
i += chunk;
}
}
if fast_unaligned && mem::size_of::<T>() == 2 {
// Use rotate-by-16 to reverse u16s in a u32
let chunk = mem::size_of::<u32>() / 2;
while i + chunk - 1 < ln / 2 {
unsafe {
let pa: *mut T = self.get_unchecked_mut(i);
let pb: *mut T = self.get_unchecked_mut(ln - i - chunk);
let va = ptr::read_unaligned(pa as *mut u32);
let vb = ptr::read_unaligned(pb as *mut u32);
ptr::write_unaligned(pa as *mut u32, vb.rotate_left(16));
ptr::write_unaligned(pb as *mut u32, va.rotate_left(16));
}
i += chunk;
}
}
while i < ln / 2 {
// Unsafe swap to avoid the bounds check in safe swap.
unsafe {
let pa: *mut T = self.get_unchecked_mut(i);
let pb: *mut T = self.get_unchecked_mut(ln - i - 1);
ptr::swap(pa, pb);
}
i += 1;
}
}
/// Returns an iterator over the slice.
///
/// # Examples
///
/// ```
/// let x = &[1, 2, 4];
/// let mut iterator = x.iter();
///
/// assert_eq!(iterator.next(), Some(&1));
/// assert_eq!(iterator.next(), Some(&2));
/// assert_eq!(iterator.next(), Some(&4));
/// assert_eq!(iterator.next(), None);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn iter(&self) -> Iter<T> {
unsafe {
let p = if mem::size_of::<T>() == 0 {
1 as *const _
} else {
let p = self.as_ptr();
assume(!p.is_null());
p
};
Iter {
ptr: p,
end: slice_offset!(p, self.len() as isize),
_marker: marker::PhantomData
}
}
}
/// Returns an iterator that allows modifying each value.
///
/// # Examples
///
/// ```
/// let x = &mut [1, 2, 4];
/// for elem in x.iter_mut() {
/// *elem += 2;
/// }
/// assert_eq!(x, &[3, 4, 6]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn iter_mut(&mut self) -> IterMut<T> {
unsafe {
let p = if mem::size_of::<T>() == 0 {
1 as *mut _
} else {
let p = self.as_mut_ptr();
assume(!p.is_null());
p
};
IterMut {
ptr: p,
end: slice_offset!(p, self.len() as isize),
_marker: marker::PhantomData
}
}
}
/// Returns an iterator over all contiguous windows of length
/// `size`. The windows overlap. If the slice is shorter than
/// `size`, the iterator returns no values.
///
/// # Panics
///
/// Panics if `size` is 0.
///
/// # Examples
///
/// ```
/// let slice = ['r', 'u', 's', 't'];
/// let mut iter = slice.windows(2);
/// assert_eq!(iter.next().unwrap(), &['r', 'u']);
/// assert_eq!(iter.next().unwrap(), &['u', 's']);
/// assert_eq!(iter.next().unwrap(), &['s', 't']);
/// assert!(iter.next().is_none());
/// ```
///
/// If the slice is shorter than `size`:
///
/// ```
/// let slice = ['f', 'o', 'o'];
/// let mut iter = slice.windows(4);
/// assert!(iter.next().is_none());
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn windows(&self, size: usize) -> Windows<T> {
assert!(size != 0);
Windows { v: self, size: size }
}
/// Returns an iterator over `chunk_size` elements of the slice at a
/// time. The chunks are slices and do not overlap. If `chunk_size` does
/// not divide the length of the slice, then the last chunk will
/// not have length `chunk_size`.
///
/// See [`exact_chunks`] for a variant of this iterator that returns chunks
/// of always exactly `chunk_size` elements.
///
/// # Panics
///
/// Panics if `chunk_size` is 0.
///
/// # Examples
///
/// ```
/// let slice = ['l', 'o', 'r', 'e', 'm'];
/// let mut iter = slice.chunks(2);
/// assert_eq!(iter.next().unwrap(), &['l', 'o']);
/// assert_eq!(iter.next().unwrap(), &['r', 'e']);
/// assert_eq!(iter.next().unwrap(), &['m']);
/// assert!(iter.next().is_none());
/// ```
///
/// [`exact_chunks`]: #method.exact_chunks
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn chunks(&self, chunk_size: usize) -> Chunks<T> {
assert!(chunk_size != 0);
Chunks { v: self, chunk_size: chunk_size }
}
/// Returns an iterator over `chunk_size` elements of the slice at a time.
/// The chunks are mutable slices, and do not overlap. If `chunk_size` does
/// not divide the length of the slice, then the last chunk will not
/// have length `chunk_size`.
///
/// See [`exact_chunks_mut`] for a variant of this iterator that returns chunks
/// of always exactly `chunk_size` elements.
///
/// # Panics
///
/// Panics if `chunk_size` is 0.
///
/// # Examples
///
/// ```
/// let v = &mut [0, 0, 0, 0, 0];
/// let mut count = 1;
///
/// for chunk in v.chunks_mut(2) {
/// for elem in chunk.iter_mut() {
/// *elem += count;
/// }
/// count += 1;
/// }
/// assert_eq!(v, &[1, 1, 2, 2, 3]);
/// ```
///
/// [`exact_chunks_mut`]: #method.exact_chunks_mut
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<T> {
assert!(chunk_size != 0);
ChunksMut { v: self, chunk_size: chunk_size }
}
/// Returns an iterator over `chunk_size` elements of the slice at a
/// time. The chunks are slices and do not overlap. If `chunk_size` does
/// not divide the length of the slice, then the last up to `chunk_size-1`
/// elements will be omitted.
///
/// Due to each chunk having exactly `chunk_size` elements, the compiler
/// can often optimize the resulting code better than in the case of
/// [`chunks`].
///
/// # Panics
///
/// Panics if `chunk_size` is 0.
///
/// # Examples
///
/// ```
/// #![feature(exact_chunks)]
///
/// let slice = ['l', 'o', 'r', 'e', 'm'];
/// let mut iter = slice.exact_chunks(2);
/// assert_eq!(iter.next().unwrap(), &['l', 'o']);
/// assert_eq!(iter.next().unwrap(), &['r', 'e']);
/// assert!(iter.next().is_none());
/// ```
///
/// [`chunks`]: #method.chunks
#[unstable(feature = "exact_chunks", issue = "47115")]
#[inline]
pub fn exact_chunks(&self, chunk_size: usize) -> ExactChunks<T> {
assert!(chunk_size != 0);
let rem = self.len() % chunk_size;
let len = self.len() - rem;
ExactChunks { v: &self[..len], chunk_size: chunk_size}
}
/// Returns an iterator over `chunk_size` elements of the slice at a time.
/// The chunks are mutable slices, and do not overlap. If `chunk_size` does
/// not divide the length of the slice, then the last up to `chunk_size-1`
/// elements will be omitted.
///
///
/// Due to each chunk having exactly `chunk_size` elements, the compiler
/// can often optimize the resulting code better than in the case of
/// [`chunks_mut`].
///
/// # Panics
///
/// Panics if `chunk_size` is 0.
///
/// # Examples
///
/// ```
/// #![feature(exact_chunks)]
///
/// let v = &mut [0, 0, 0, 0, 0];
/// let mut count = 1;
///
/// for chunk in v.exact_chunks_mut(2) {
/// for elem in chunk.iter_mut() {
/// *elem += count;
/// }
/// count += 1;
/// }
/// assert_eq!(v, &[1, 1, 2, 2, 0]);
/// ```
///
/// [`chunks_mut`]: #method.chunks_mut
#[unstable(feature = "exact_chunks", issue = "47115")]
#[inline]
pub fn exact_chunks_mut(&mut self, chunk_size: usize) -> ExactChunksMut<T> {
assert!(chunk_size != 0);
let rem = self.len() % chunk_size;
let len = self.len() - rem;
ExactChunksMut { v: &mut self[..len], chunk_size: chunk_size}
}
/// Divides one slice into two at an index.
///
/// The first will contain all indices from `[0, mid)` (excluding
/// the index `mid` itself) and the second will contain all
/// indices from `[mid, len)` (excluding the index `len` itself).
///
/// # Panics
///
/// Panics if `mid > len`.
///
/// # Examples
///
/// ```
/// let v = [1, 2, 3, 4, 5, 6];
///
/// {
/// let (left, right) = v.split_at(0);
/// assert!(left == []);
/// assert!(right == [1, 2, 3, 4, 5, 6]);
/// }
///
/// {
/// let (left, right) = v.split_at(2);
/// assert!(left == [1, 2]);
/// assert!(right == [3, 4, 5, 6]);
/// }
///
/// {
/// let (left, right) = v.split_at(6);
/// assert!(left == [1, 2, 3, 4, 5, 6]);
/// assert!(right == []);
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn split_at(&self, mid: usize) -> (&[T], &[T]) {
(&self[..mid], &self[mid..])
}
/// Divides one mutable slice into two at an index.
///
/// The first will contain all indices from `[0, mid)` (excluding
/// the index `mid` itself) and the second will contain all
/// indices from `[mid, len)` (excluding the index `len` itself).
///
/// # Panics
///
/// Panics if `mid > len`.
///
/// # Examples
///
/// ```
/// let mut v = [1, 0, 3, 0, 5, 6];
/// // scoped to restrict the lifetime of the borrows
/// {
/// let (left, right) = v.split_at_mut(2);
/// assert!(left == [1, 0]);
/// assert!(right == [3, 0, 5, 6]);
/// left[1] = 2;
/// right[1] = 4;
/// }
/// assert!(v == [1, 2, 3, 4, 5, 6]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn split_at_mut(&mut self, mid: usize) -> (&mut [T], &mut [T]) {
let len = self.len();
let ptr = self.as_mut_ptr();
unsafe {
assert!(mid <= len);
(from_raw_parts_mut(ptr, mid),
from_raw_parts_mut(ptr.offset(mid as isize), len - mid))
}
}
/// Returns an iterator over subslices separated by elements that match
/// `pred`. The matched element is not contained in the subslices.
///
/// # Examples
///
/// ```
/// let slice = [10, 40, 33, 20];
/// let mut iter = slice.split(|num| num % 3 == 0);
///
/// assert_eq!(iter.next().unwrap(), &[10, 40]);
/// assert_eq!(iter.next().unwrap(), &[20]);
/// assert!(iter.next().is_none());
/// ```
///
/// If the first element is matched, an empty slice will be the first item
/// returned by the iterator. Similarly, if the last element in the slice
/// is matched, an empty slice will be the last item returned by the
/// iterator:
///
/// ```
/// let slice = [10, 40, 33];
/// let mut iter = slice.split(|num| num % 3 == 0);
///
/// assert_eq!(iter.next().unwrap(), &[10, 40]);
/// assert_eq!(iter.next().unwrap(), &[]);
/// assert!(iter.next().is_none());
/// ```
///
/// If two matched elements are directly adjacent, an empty slice will be
/// present between them:
///
/// ```
/// let slice = [10, 6, 33, 20];
/// let mut iter = slice.split(|num| num % 3 == 0);
///
/// assert_eq!(iter.next().unwrap(), &[10]);
/// assert_eq!(iter.next().unwrap(), &[]);
/// assert_eq!(iter.next().unwrap(), &[20]);
/// assert!(iter.next().is_none());
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn split<F>(&self, pred: F) -> Split<T, F>
where F: FnMut(&T) -> bool
{
Split {
v: self,
pred,
finished: false
}
}
/// Returns an iterator over mutable subslices separated by elements that
/// match `pred`. The matched element is not contained in the subslices.
///
/// # Examples
///
/// ```
/// let mut v = [10, 40, 30, 20, 60, 50];
///
/// for group in v.split_mut(|num| *num % 3 == 0) {
/// group[0] = 1;
/// }
/// assert_eq!(v, [1, 40, 30, 1, 60, 1]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn split_mut<F>(&mut self, pred: F) -> SplitMut<T, F>
where F: FnMut(&T) -> bool
{
SplitMut { v: self, pred: pred, finished: false }
}
/// Returns an iterator over subslices separated by elements that match
/// `pred`, starting at the end of the slice and working backwards.
/// The matched element is not contained in the subslices.
///
/// # Examples
///
/// ```
/// let slice = [11, 22, 33, 0, 44, 55];
/// let mut iter = slice.rsplit(|num| *num == 0);
///
/// assert_eq!(iter.next().unwrap(), &[44, 55]);
/// assert_eq!(iter.next().unwrap(), &[11, 22, 33]);
/// assert_eq!(iter.next(), None);
/// ```
///
/// As with `split()`, if the first or last element is matched, an empty
/// slice will be the first (or last) item returned by the iterator.
///
/// ```
/// let v = &[0, 1, 1, 2, 3, 5, 8];
/// let mut it = v.rsplit(|n| *n % 2 == 0);
/// assert_eq!(it.next().unwrap(), &[]);
/// assert_eq!(it.next().unwrap(), &[3, 5]);
/// assert_eq!(it.next().unwrap(), &[1, 1]);
/// assert_eq!(it.next().unwrap(), &[]);
/// assert_eq!(it.next(), None);
/// ```
#[stable(feature = "slice_rsplit", since = "1.27.0")]
#[inline]
pub fn rsplit<F>(&self, pred: F) -> RSplit<T, F>
where F: FnMut(&T) -> bool
{
RSplit { inner: self.split(pred) }
}
/// Returns an iterator over mutable subslices separated by elements that
/// match `pred`, starting at the end of the slice and working
/// backwards. The matched element is not contained in the subslices.
///
/// # Examples
///
/// ```
/// let mut v = [100, 400, 300, 200, 600, 500];
///
/// let mut count = 0;
/// for group in v.rsplit_mut(|num| *num % 3 == 0) {
/// count += 1;
/// group[0] = count;
/// }
/// assert_eq!(v, [3, 400, 300, 2, 600, 1]);
/// ```
///
#[stable(feature = "slice_rsplit", since = "1.27.0")]
#[inline]
pub fn rsplit_mut<F>(&mut self, pred: F) -> RSplitMut<T, F>
where F: FnMut(&T) -> bool
{
RSplitMut { inner: self.split_mut(pred) }
}
/// Returns an iterator over subslices separated by elements that match
/// `pred`, limited to returning at most `n` items. The matched element is
/// not contained in the subslices.
///
/// The last element returned, if any, will contain the remainder of the
/// slice.
///
/// # Examples
///
/// Print the slice split once by numbers divisible by 3 (i.e. `[10, 40]`,
/// `[20, 60, 50]`):
///
/// ```
/// let v = [10, 40, 30, 20, 60, 50];
///
/// for group in v.splitn(2, |num| *num % 3 == 0) {
/// println!("{:?}", group);
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn splitn<F>(&self, n: usize, pred: F) -> SplitN<T, F>
where F: FnMut(&T) -> bool
{
SplitN {
inner: GenericSplitN {
iter: self.split(pred),
count: n
}
}
}
/// Returns an iterator over subslices separated by elements that match
/// `pred`, limited to returning at most `n` items. The matched element is
/// not contained in the subslices.
///
/// The last element returned, if any, will contain the remainder of the
/// slice.
///
/// # Examples
///
/// ```
/// let mut v = [10, 40, 30, 20, 60, 50];
///
/// for group in v.splitn_mut(2, |num| *num % 3 == 0) {
/// group[0] = 1;
/// }
/// assert_eq!(v, [1, 40, 30, 1, 60, 50]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn splitn_mut<F>(&mut self, n: usize, pred: F) -> SplitNMut<T, F>
where F: FnMut(&T) -> bool
{
SplitNMut {
inner: GenericSplitN {
iter: self.split_mut(pred),
count: n
}
}
}
/// Returns an iterator over subslices separated by elements that match
/// `pred` limited to returning at most `n` items. This starts at the end of
/// the slice and works backwards. The matched element is not contained in
/// the subslices.
///
/// The last element returned, if any, will contain the remainder of the
/// slice.
///
/// # Examples
///
/// Print the slice split once, starting from the end, by numbers divisible
/// by 3 (i.e. `[50]`, `[10, 40, 30, 20]`):
///
/// ```
/// let v = [10, 40, 30, 20, 60, 50];
///
/// for group in v.rsplitn(2, |num| *num % 3 == 0) {
/// println!("{:?}", group);
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn rsplitn<F>(&self, n: usize, pred: F) -> RSplitN<T, F>
where F: FnMut(&T) -> bool
{
RSplitN {
inner: GenericSplitN {
iter: self.rsplit(pred),
count: n
}
}
}
/// Returns an iterator over subslices separated by elements that match
/// `pred` limited to returning at most `n` items. This starts at the end of
/// the slice and works backwards. The matched element is not contained in
/// the subslices.
///
/// The last element returned, if any, will contain the remainder of the
/// slice.
///
/// # Examples
///
/// ```
/// let mut s = [10, 40, 30, 20, 60, 50];
///
/// for group in s.rsplitn_mut(2, |num| *num % 3 == 0) {
/// group[0] = 1;
/// }
/// assert_eq!(s, [1, 40, 30, 20, 60, 1]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn rsplitn_mut<F>(&mut self, n: usize, pred: F) -> RSplitNMut<T, F>
where F: FnMut(&T) -> bool
{
RSplitNMut {
inner: GenericSplitN {
iter: self.rsplit_mut(pred),
count: n
}
}
}
/// Returns `true` if the slice contains an element with the given value.
///
/// # Examples
///
/// ```
/// let v = [10, 40, 30];
/// assert!(v.contains(&30));
/// assert!(!v.contains(&50));
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn contains(&self, x: &T) -> bool
where T: PartialEq
{
x.slice_contains(self)
}
/// Returns `true` if `needle` is a prefix of the slice.
///
/// # Examples
///
/// ```
/// let v = [10, 40, 30];
/// assert!(v.starts_with(&[10]));
/// assert!(v.starts_with(&[10, 40]));
/// assert!(!v.starts_with(&[50]));
/// assert!(!v.starts_with(&[10, 50]));
/// ```
///
/// Always returns `true` if `needle` is an empty slice:
///
/// ```
/// let v = &[10, 40, 30];
/// assert!(v.starts_with(&[]));
/// let v: &[u8] = &[];
/// assert!(v.starts_with(&[]));
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn starts_with(&self, needle: &[T]) -> bool
where T: PartialEq
{
let n = needle.len();
self.len() >= n && needle == &self[..n]
}
/// Returns `true` if `needle` is a suffix of the slice.
///
/// # Examples
///
/// ```
/// let v = [10, 40, 30];
/// assert!(v.ends_with(&[30]));
/// assert!(v.ends_with(&[40, 30]));
/// assert!(!v.ends_with(&[50]));
/// assert!(!v.ends_with(&[50, 30]));
/// ```
///
/// Always returns `true` if `needle` is an empty slice:
///
/// ```
/// let v = &[10, 40, 30];
/// assert!(v.ends_with(&[]));
/// let v: &[u8] = &[];
/// assert!(v.ends_with(&[]));
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn ends_with(&self, needle: &[T]) -> bool
where T: PartialEq
{
let (m, n) = (self.len(), needle.len());
m >= n && needle == &self[m-n..]
}
/// Binary searches this sorted slice for a given element.
///
/// If the value is found then `Ok` is returned, containing the
/// index of the matching element; if the value is not found then
/// `Err` is returned, containing the index where a matching
/// element could be inserted while maintaining sorted order.
///
/// # Examples
///
/// Looks up a series of four elements. The first is found, with a
/// uniquely determined position; the second and third are not
/// found; the fourth could match any position in `[1, 4]`.
///
/// ```
/// let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
///
/// assert_eq!(s.binary_search(&13), Ok(9));
/// assert_eq!(s.binary_search(&4), Err(7));
/// assert_eq!(s.binary_search(&100), Err(13));
/// let r = s.binary_search(&1);
/// assert!(match r { Ok(1..=4) => true, _ => false, });
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn binary_search(&self, x: &T) -> Result<usize, usize>
where T: Ord
{
self.binary_search_by(|p| p.cmp(x))
}
/// Binary searches this sorted slice with a comparator function.
///
/// The comparator function should implement an order consistent
/// with the sort order of the underlying slice, returning an
/// order code that indicates whether its argument is `Less`,
/// `Equal` or `Greater` the desired target.
///
/// If a matching value is found then returns `Ok`, containing
/// the index for the matched element; if no match is found then
/// `Err` is returned, containing the index where a matching
/// element could be inserted while maintaining sorted order.
///
/// # Examples
///
/// Looks up a series of four elements. The first is found, with a
/// uniquely determined position; the second and third are not
/// found; the fourth could match any position in `[1, 4]`.
///
/// ```
/// let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
///
/// let seek = 13;
/// assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Ok(9));
/// let seek = 4;
/// assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(7));
/// let seek = 100;
/// assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(13));
/// let seek = 1;
/// let r = s.binary_search_by(|probe| probe.cmp(&seek));
/// assert!(match r { Ok(1..=4) => true, _ => false, });
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn binary_search_by<'a, F>(&'a self, mut f: F) -> Result<usize, usize>
where F: FnMut(&'a T) -> Ordering
{
let s = self;
let mut size = s.len();
if size == 0 {
return Err(0);
}
let mut base = 0usize;
while size > 1 {
let half = size / 2;
let mid = base + half;
// mid is always in [0, size), that means mid is >= 0 and < size.
// mid >= 0: by definition
// mid < size: mid = size / 2 + size / 4 + size / 8 ...
let cmp = f(unsafe { s.get_unchecked(mid) });
base = if cmp == Greater { base } else { mid };
size -= half;
}
// base is always in [0, size) because base <= mid.
let cmp = f(unsafe { s.get_unchecked(base) });
if cmp == Equal { Ok(base) } else { Err(base + (cmp == Less) as usize) }
}
/// Binary searches this sorted slice with a key extraction function.
///
/// Assumes that the slice is sorted by the key, for instance with
/// [`sort_by_key`] using the same key extraction function.
///
/// If a matching value is found then returns `Ok`, containing the
/// index for the matched element; if no match is found then `Err`
/// is returned, containing the index where a matching element could
/// be inserted while maintaining sorted order.
///
/// [`sort_by_key`]: #method.sort_by_key
///
/// # Examples
///
/// Looks up a series of four elements in a slice of pairs sorted by
/// their second elements. The first is found, with a uniquely
/// determined position; the second and third are not found; the
/// fourth could match any position in `[1, 4]`.
///
/// ```
/// let s = [(0, 0), (2, 1), (4, 1), (5, 1), (3, 1),
/// (1, 2), (2, 3), (4, 5), (5, 8), (3, 13),
/// (1, 21), (2, 34), (4, 55)];
///
/// assert_eq!(s.binary_search_by_key(&13, |&(a,b)| b), Ok(9));
/// assert_eq!(s.binary_search_by_key(&4, |&(a,b)| b), Err(7));
/// assert_eq!(s.binary_search_by_key(&100, |&(a,b)| b), Err(13));
/// let r = s.binary_search_by_key(&1, |&(a,b)| b);
/// assert!(match r { Ok(1..=4) => true, _ => false, });
/// ```
#[stable(feature = "slice_binary_search_by_key", since = "1.10.0")]
#[inline]
pub fn binary_search_by_key<'a, B, F>(&'a self, b: &B, mut f: F) -> Result<usize, usize>
where F: FnMut(&'a T) -> B,
B: Ord
{
self.binary_search_by(|k| f(k).cmp(b))
}
/// Sorts the slice, but may not preserve the order of equal elements.
///
/// This sort is unstable (i.e. may reorder equal elements), in-place (i.e. does not allocate),
/// and `O(n log n)` worst-case.
///
/// # Current implementation
///
/// The current algorithm is based on [pattern-defeating quicksort][pdqsort] by Orson Peters,
/// which combines the fast average case of randomized quicksort with the fast worst case of
/// heapsort, while achieving linear time on slices with certain patterns. It uses some
/// randomization to avoid degenerate cases, but with a fixed seed to always provide
/// deterministic behavior.
///
/// It is typically faster than stable sorting, except in a few special cases, e.g. when the
/// slice consists of several concatenated sorted sequences.
///
/// # Examples
///
/// ```
/// let mut v = [-5, 4, 1, -3, 2];
///
/// v.sort_unstable();
/// assert!(v == [-5, -3, 1, 2, 4]);
/// ```
///
/// [pdqsort]: https://github.com/orlp/pdqsort
#[stable(feature = "sort_unstable", since = "1.20.0")]
#[inline]
pub fn sort_unstable(&mut self)
where T: Ord
{
sort::quicksort(self, |a, b| a.lt(b));
}
/// Sorts the slice with a comparator function, but may not preserve the order of equal
/// elements.
///
/// This sort is unstable (i.e. may reorder equal elements), in-place (i.e. does not allocate),
/// and `O(n log n)` worst-case.
///
/// # Current implementation
///
/// The current algorithm is based on [pattern-defeating quicksort][pdqsort] by Orson Peters,
/// which combines the fast average case of randomized quicksort with the fast worst case of
/// heapsort, while achieving linear time on slices with certain patterns. It uses some
/// randomization to avoid degenerate cases, but with a fixed seed to always provide
/// deterministic behavior.
///
/// It is typically faster than stable sorting, except in a few special cases, e.g. when the
/// slice consists of several concatenated sorted sequences.
///
/// # Examples
///
/// ```
/// let mut v = [5, 4, 1, 3, 2];
/// v.sort_unstable_by(|a, b| a.cmp(b));
/// assert!(v == [1, 2, 3, 4, 5]);
///
/// // reverse sorting
/// v.sort_unstable_by(|a, b| b.cmp(a));
/// assert!(v == [5, 4, 3, 2, 1]);
/// ```
///
/// [pdqsort]: https://github.com/orlp/pdqsort
#[stable(feature = "sort_unstable", since = "1.20.0")]
#[inline]
pub fn sort_unstable_by<F>(&mut self, mut compare: F)
where F: FnMut(&T, &T) -> Ordering
{
sort::quicksort(self, |a, b| compare(a, b) == Ordering::Less);
}
/// Sorts the slice with a key extraction function, but may not preserve the order of equal
/// elements.
///
/// This sort is unstable (i.e. may reorder equal elements), in-place (i.e. does not allocate),
/// and `O(m n log(m n))` worst-case, where the key function is `O(m)`.
///
/// # Current implementation
///
/// The current algorithm is based on [pattern-defeating quicksort][pdqsort] by Orson Peters,
/// which combines the fast average case of randomized quicksort with the fast worst case of
/// heapsort, while achieving linear time on slices with certain patterns. It uses some
/// randomization to avoid degenerate cases, but with a fixed seed to always provide
/// deterministic behavior.
///
/// # Examples
///
/// ```
/// let mut v = [-5i32, 4, 1, -3, 2];
///
/// v.sort_unstable_by_key(|k| k.abs());
/// assert!(v == [1, 2, -3, 4, -5]);
/// ```
///
/// [pdqsort]: https://github.com/orlp/pdqsort
#[stable(feature = "sort_unstable", since = "1.20.0")]
#[inline]
pub fn sort_unstable_by_key<K, F>(&mut self, mut f: F)
where F: FnMut(&T) -> K, K: Ord
{
sort::quicksort(self, |a, b| f(a).lt(&f(b)));
}
/// Rotates the slice in-place such that the first `mid` elements of the
/// slice move to the end while the last `self.len() - mid` elements move to
/// the front. After calling `rotate_left`, the element previously at index
/// `mid` will become the first element in the slice.
///
/// # Panics
///
/// This function will panic if `mid` is greater than the length of the
/// slice. Note that `mid == self.len()` does _not_ panic and is a no-op
/// rotation.
///
/// # Complexity
///
/// Takes linear (in `self.len()`) time.
///
/// # Examples
///
/// ```
/// let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
/// a.rotate_left(2);
/// assert_eq!(a, ['c', 'd', 'e', 'f', 'a', 'b']);
/// ```
///
/// Rotating a subslice:
///
/// ```
/// let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
/// a[1..5].rotate_left(1);
/// assert_eq!(a, ['a', 'c', 'd', 'e', 'b', 'f']);
/// ```
#[stable(feature = "slice_rotate", since = "1.26.0")]
pub fn rotate_left(&mut self, mid: usize) {
assert!(mid <= self.len());
let k = self.len() - mid;
unsafe {
let p = self.as_mut_ptr();
rotate::ptr_rotate(mid, p.offset(mid as isize), k);
}
}
/// Rotates the slice in-place such that the first `self.len() - k`
/// elements of the slice move to the end while the last `k` elements move
/// to the front. After calling `rotate_right`, the element previously at
/// index `self.len() - k` will become the first element in the slice.
///
/// # Panics
///
/// This function will panic if `k` is greater than the length of the
/// slice. Note that `k == self.len()` does _not_ panic and is a no-op
/// rotation.
///
/// # Complexity
///
/// Takes linear (in `self.len()`) time.
///
/// # Examples
///
/// ```
/// let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
/// a.rotate_right(2);
/// assert_eq!(a, ['e', 'f', 'a', 'b', 'c', 'd']);
/// ```
///
/// Rotate a subslice:
///
/// ```
/// let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
/// a[1..5].rotate_right(1);
/// assert_eq!(a, ['a', 'e', 'b', 'c', 'd', 'f']);
/// ```
#[stable(feature = "slice_rotate", since = "1.26.0")]
pub fn rotate_right(&mut self, k: usize) {
assert!(k <= self.len());
let mid = self.len() - k;
unsafe {
let p = self.as_mut_ptr();
rotate::ptr_rotate(mid, p.offset(mid as isize), k);
}
}
/// Copies the elements from `src` into `self`.
///
/// The length of `src` must be the same as `self`.
///
/// If `src` implements `Copy`, it can be more performant to use
/// [`copy_from_slice`].
///
/// # Panics
///
/// This function will panic if the two slices have different lengths.
///
/// # Examples
///
/// Cloning two elements from a slice into another:
///
/// ```
/// let src = [1, 2, 3, 4];
/// let mut dst = [0, 0];
///
/// dst.clone_from_slice(&src[2..]);
///
/// assert_eq!(src, [1, 2, 3, 4]);
/// assert_eq!(dst, [3, 4]);
/// ```
///
/// Rust enforces that there can only be one mutable reference with no
/// immutable references to a particular piece of data in a particular
/// scope. Because of this, attempting to use `clone_from_slice` on a
/// single slice will result in a compile failure:
///
/// ```compile_fail
/// let mut slice = [1, 2, 3, 4, 5];
///
/// slice[..2].clone_from_slice(&slice[3..]); // compile fail!
/// ```
///
/// To work around this, we can use [`split_at_mut`] to create two distinct
/// sub-slices from a slice:
///
/// ```
/// let mut slice = [1, 2, 3, 4, 5];
///
/// {
/// let (left, right) = slice.split_at_mut(2);
/// left.clone_from_slice(&right[1..]);
/// }
///
/// assert_eq!(slice, [4, 5, 3, 4, 5]);
/// ```
///
/// [`copy_from_slice`]: #method.copy_from_slice
/// [`split_at_mut`]: #method.split_at_mut
#[stable(feature = "clone_from_slice", since = "1.7.0")]
pub fn clone_from_slice(&mut self, src: &[T]) where T: Clone {
assert!(self.len() == src.len(),
"destination and source slices have different lengths");
// NOTE: We need to explicitly slice them to the same length
// for bounds checking to be elided, and the optimizer will
// generate memcpy for simple cases (for example T = u8).
let len = self.len();
let src = &src[..len];
for i in 0..len {
self[i].clone_from(&src[i]);
}
}
/// Copies all elements from `src` into `self`, using a memcpy.
///
/// The length of `src` must be the same as `self`.
///
/// If `src` does not implement `Copy`, use [`clone_from_slice`].
///
/// # Panics
///
/// This function will panic if the two slices have different lengths.
///
/// # Examples
///
/// Copying two elements from a slice into another:
///
/// ```
/// let src = [1, 2, 3, 4];
/// let mut dst = [0, 0];
///
/// dst.copy_from_slice(&src[2..]);
///
/// assert_eq!(src, [1, 2, 3, 4]);
/// assert_eq!(dst, [3, 4]);
/// ```
///
/// Rust enforces that there can only be one mutable reference with no
/// immutable references to a particular piece of data in a particular
/// scope. Because of this, attempting to use `copy_from_slice` on a
/// single slice will result in a compile failure:
///
/// ```compile_fail
/// let mut slice = [1, 2, 3, 4, 5];
///
/// slice[..2].copy_from_slice(&slice[3..]); // compile fail!
/// ```
///
/// To work around this, we can use [`split_at_mut`] to create two distinct
/// sub-slices from a slice:
///
/// ```
/// let mut slice = [1, 2, 3, 4, 5];
///
/// {
/// let (left, right) = slice.split_at_mut(2);
/// left.copy_from_slice(&right[1..]);
/// }
///
/// assert_eq!(slice, [4, 5, 3, 4, 5]);
/// ```
///
/// [`clone_from_slice`]: #method.clone_from_slice
/// [`split_at_mut`]: #method.split_at_mut
#[stable(feature = "copy_from_slice", since = "1.9.0")]
pub fn copy_from_slice(&mut self, src: &[T]) where T: Copy {
assert!(self.len() == src.len(),
"destination and source slices have different lengths");
unsafe {
ptr::copy_nonoverlapping(
src.as_ptr(), self.as_mut_ptr(), self.len());
}
}
/// Swaps all elements in `self` with those in `other`.
///
/// The length of `other` must be the same as `self`.
///
/// # Panics
///
/// This function will panic if the two slices have different lengths.
///
/// # Example
///
/// Swapping two elements across slices:
///
/// ```
/// let mut slice1 = [0, 0];
/// let mut slice2 = [1, 2, 3, 4];
///
/// slice1.swap_with_slice(&mut slice2[2..]);
///
/// assert_eq!(slice1, [3, 4]);
/// assert_eq!(slice2, [1, 2, 0, 0]);
/// ```
///
/// Rust enforces that there can only be one mutable reference to a
/// particular piece of data in a particular scope. Because of this,
/// attempting to use `swap_with_slice` on a single slice will result in
/// a compile failure:
///
/// ```compile_fail
/// let mut slice = [1, 2, 3, 4, 5];
/// slice[..2].swap_with_slice(&mut slice[3..]); // compile fail!
/// ```
///
/// To work around this, we can use [`split_at_mut`] to create two distinct
/// mutable sub-slices from a slice:
///
/// ```
/// let mut slice = [1, 2, 3, 4, 5];
///
/// {
/// let (left, right) = slice.split_at_mut(2);
/// left.swap_with_slice(&mut right[1..]);
/// }
///
/// assert_eq!(slice, [4, 5, 3, 1, 2]);
/// ```
///
/// [`split_at_mut`]: #method.split_at_mut
#[stable(feature = "swap_with_slice", since = "1.27.0")]
pub fn swap_with_slice(&mut self, other: &mut [T]) {
assert!(self.len() == other.len(),
"destination and source slices have different lengths");
unsafe {
ptr::swap_nonoverlapping(
self.as_mut_ptr(), other.as_mut_ptr(), self.len());
}
}
/// Function to calculate lenghts of the middle and trailing slice for `align_to{,_mut}`.
fn align_to_offsets<U>(&self) -> (usize, usize) {
// What we gonna do about `rest` is figure out what multiple of `U`s we can put in a
// lowest number of `T`s. And how many `T`s we need for each such "multiple".
//
// Consider for example T=u8 U=u16. Then we can put 1 U in 2 Ts. Simple. Now, consider
// for example a case where size_of::<T> = 16, size_of::<U> = 24. We can put 2 Us in
// place of every 3 Ts in the `rest` slice. A bit more complicated.
//
// Formula to calculate this is:
//
// Us = lcm(size_of::<T>, size_of::<U>) / size_of::<U>
// Ts = lcm(size_of::<T>, size_of::<U>) / size_of::<T>
//
// Expanded and simplified:
//
// Us = size_of::<T> / gcd(size_of::<T>, size_of::<U>)
// Ts = size_of::<U> / gcd(size_of::<T>, size_of::<U>)
//
// Luckily since all this is constant-evaluated... performance here matters not!
#[inline]
fn gcd(a: usize, b: usize) -> usize {
// iterative stein’s algorithm
// We should still make this `const fn` (and revert to recursive algorithm if we do)
// because relying on llvm to consteval all this is… well, it makes me
let (ctz_a, mut ctz_b) = unsafe {
if a == 0 { return b; }
if b == 0 { return a; }
(::intrinsics::cttz_nonzero(a), ::intrinsics::cttz_nonzero(b))
};
let k = ctz_a.min(ctz_b);
let mut a = a >> ctz_a;
let mut b = b;
loop {
// remove all factors of 2 from b
b >>= ctz_b;
if a > b {
::mem::swap(&mut a, &mut b);
}
b = b - a;
unsafe {
if b == 0 {
break;
}
ctz_b = ::intrinsics::cttz_nonzero(b);
}
}
return a << k;
}
let gcd: usize = gcd(::mem::size_of::<T>(), ::mem::size_of::<U>());
let ts: usize = ::mem::size_of::<U>() / gcd;
let us: usize = ::mem::size_of::<T>() / gcd;
// Armed with this knowledge, we can find how many `U`s we can fit!
let us_len = self.len() / ts * us;
// And how many `T`s will be in the trailing slice!
let ts_len = self.len() % ts;
return (us_len, ts_len);
}
/// Transmute the slice to a slice of another type, ensuring aligment of the types is
/// maintained.
///
/// This method splits the slice into three distinct slices: prefix, correctly aligned middle
/// slice of a new type, and the suffix slice. The middle slice will have the greatest length
/// possible for a given type and input slice.
///
/// This method has no purpose when either input element `T` or output element `U` are
/// zero-sized and will return the original slice without splitting anything.
///
/// # Unsafety
///
/// This method is essentially a `transmute` with respect to the elements in the returned
/// middle slice, so all the usual caveats pertaining to `transmute::<T, U>` also apply here.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// # #![feature(slice_align_to)]
/// unsafe {
/// let bytes: [u8; 7] = [1, 2, 3, 4, 5, 6, 7];
/// let (prefix, shorts, suffix) = bytes.align_to::<u16>();
/// // less_efficient_algorithm_for_bytes(prefix);
/// // more_efficient_algorithm_for_aligned_shorts(shorts);
/// // less_efficient_algorithm_for_bytes(suffix);
/// }
/// ```
#[unstable(feature = "slice_align_to", issue = "44488")]
pub unsafe fn align_to<U>(&self) -> (&[T], &[U], &[T]) {
// Note that most of this function will be constant-evaluated,
if ::mem::size_of::<U>() == 0 || ::mem::size_of::<T>() == 0 {
// handle ZSTs specially, which is – don't handle them at all.
return (self, &[], &[]);
}
// First, find at what point do we split between the first and 2nd slice. Easy with
// ptr.align_offset.
let ptr = self.as_ptr();
let offset = ::ptr::align_offset(ptr, ::mem::align_of::<U>());
if offset > self.len() {
return (self, &[], &[]);
} else {
let (left, rest) = self.split_at(offset);
let (us_len, ts_len) = rest.align_to_offsets::<U>();
return (left,
from_raw_parts(rest.as_ptr() as *const U, us_len),
from_raw_parts(rest.as_ptr().offset((rest.len() - ts_len) as isize), ts_len))
}
}
/// Transmute the slice to a slice of another type, ensuring aligment of the types is
/// maintained.
///
/// This method splits the slice into three distinct slices: prefix, correctly aligned middle
/// slice of a new type, and the suffix slice. The middle slice will have the greatest length
/// possible for a given type and input slice.
///
/// This method has no purpose when either input element `T` or output element `U` are
/// zero-sized and will return the original slice without splitting anything.
///
/// # Unsafety
///
/// This method is essentially a `transmute` with respect to the elements in the returned
/// middle slice, so all the usual caveats pertaining to `transmute::<T, U>` also apply here.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// # #![feature(slice_align_to)]
/// unsafe {
/// let mut bytes: [u8; 7] = [1, 2, 3, 4, 5, 6, 7];
/// let (prefix, shorts, suffix) = bytes.align_to_mut::<u16>();
/// // less_efficient_algorithm_for_bytes(prefix);
/// // more_efficient_algorithm_for_aligned_shorts(shorts);
/// // less_efficient_algorithm_for_bytes(suffix);
/// }
/// ```
#[unstable(feature = "slice_align_to", issue = "44488")]
pub unsafe fn align_to_mut<U>(&mut self) -> (&mut [T], &mut [U], &mut [T]) {
// Note that most of this function will be constant-evaluated,
if ::mem::size_of::<U>() == 0 || ::mem::size_of::<T>() == 0 {
// handle ZSTs specially, which is – don't handle them at all.
return (self, &mut [], &mut []);
}
// First, find at what point do we split between the first and 2nd slice. Easy with
// ptr.align_offset.
let ptr = self.as_ptr();
let offset = ::ptr::align_offset(ptr, ::mem::align_of::<U>());
if offset > self.len() {
return (self, &mut [], &mut []);
} else {
let (left, rest) = self.split_at_mut(offset);
let (us_len, ts_len) = rest.align_to_offsets::<U>();
let mut_ptr = rest.as_mut_ptr();
return (left,
from_raw_parts_mut(mut_ptr as *mut U, us_len),
from_raw_parts_mut(mut_ptr.offset((rest.len() - ts_len) as isize), ts_len))
}
}
}
#[lang = "slice_u8"]
#[cfg(not(test))]
impl [u8] {
/// Checks if all bytes in this slice are within the ASCII range.
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
#[inline]
pub fn is_ascii(&self) -> bool {
self.iter().all(|b| b.is_ascii())
}
/// Checks that two slices are an ASCII case-insensitive match.
///
/// Same as `to_ascii_lowercase(a) == to_ascii_lowercase(b)`,
/// but without allocating and copying temporaries.
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
#[inline]
pub fn eq_ignore_ascii_case(&self, other: &[u8]) -> bool {
self.len() == other.len() &&
self.iter().zip(other).all(|(a, b)| {
a.eq_ignore_ascii_case(b)
})
}
/// Converts this slice to its ASCII upper case equivalent in-place.
///
/// ASCII letters 'a' to 'z' are mapped to 'A' to 'Z',
/// but non-ASCII letters are unchanged.
///
/// To return a new uppercased value without modifying the existing one, use
/// [`to_ascii_uppercase`].
///
/// [`to_ascii_uppercase`]: #method.to_ascii_uppercase
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
#[inline]
pub fn make_ascii_uppercase(&mut self) {
for byte in self {
byte.make_ascii_uppercase();
}
}
/// Converts this slice to its ASCII lower case equivalent in-place.
///
/// ASCII letters 'A' to 'Z' are mapped to 'a' to 'z',
/// but non-ASCII letters are unchanged.
///
/// To return a new lowercased value without modifying the existing one, use
/// [`to_ascii_lowercase`].
///
/// [`to_ascii_lowercase`]: #method.to_ascii_lowercase
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
#[inline]
pub fn make_ascii_lowercase(&mut self) {
for byte in self {
byte.make_ascii_lowercase();
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_on_unimplemented = "slice indices are of type `usize` or ranges of `usize`"]
impl<T, I> ops::Index<I> for [T]
where I: SliceIndex<[T]>
{
type Output = I::Output;
#[inline]
fn index(&self, index: I) -> &I::Output {
index.index(self)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_on_unimplemented = "slice indices are of type `usize` or ranges of `usize`"]
impl<T, I> ops::IndexMut<I> for [T]
where I: SliceIndex<[T]>
{
#[inline]
fn index_mut(&mut self, index: I) -> &mut I::Output {
index.index_mut(self)
}
}
#[inline(never)]
#[cold]
fn slice_index_len_fail(index: usize, len: usize) -> ! {
panic!("index {} out of range for slice of length {}", index, len);
}
#[inline(never)]
#[cold]
fn slice_index_order_fail(index: usize, end: usize) -> ! {
panic!("slice index starts at {} but ends at {}", index, end);
}
#[inline(never)]
#[cold]
fn slice_index_overflow_fail() -> ! {
panic!("attempted to index slice up to maximum usize");
}
mod private_slice_index {
use super::ops;
#[stable(feature = "slice_get_slice", since = "1.28.0")]
pub trait Sealed {}
#[stable(feature = "slice_get_slice", since = "1.28.0")]
impl Sealed for usize {}
#[stable(feature = "slice_get_slice", since = "1.28.0")]
impl Sealed for ops::Range<usize> {}
#[stable(feature = "slice_get_slice", since = "1.28.0")]
impl Sealed for ops::RangeTo<usize> {}
#[stable(feature = "slice_get_slice", since = "1.28.0")]
impl Sealed for ops::RangeFrom<usize> {}
#[stable(feature = "slice_get_slice", since = "1.28.0")]
impl Sealed for ops::RangeFull {}
#[stable(feature = "slice_get_slice", since = "1.28.0")]
impl Sealed for ops::RangeInclusive<usize> {}
#[stable(feature = "slice_get_slice", since = "1.28.0")]
impl Sealed for ops::RangeToInclusive<usize> {}
}
/// A helper trait used for indexing operations.
#[stable(feature = "slice_get_slice", since = "1.28.0")]
#[rustc_on_unimplemented = "slice indices are of type `usize` or ranges of `usize`"]
pub trait SliceIndex<T: ?Sized>: private_slice_index::Sealed {
/// The output type returned by methods.
#[stable(feature = "slice_get_slice", since = "1.28.0")]
type Output: ?Sized;
/// Returns a shared reference to the output at this location, if in
/// bounds.
#[unstable(feature = "slice_index_methods", issue = "0")]
fn get(self, slice: &T) -> Option<&Self::Output>;
/// Returns a mutable reference to the output at this location, if in
/// bounds.
#[unstable(feature = "slice_index_methods", issue = "0")]
fn get_mut(self, slice: &mut T) -> Option<&mut Self::Output>;
/// Returns a shared reference to the output at this location, without
/// performing any bounds checking.
#[unstable(feature = "slice_index_methods", issue = "0")]
unsafe fn get_unchecked(self, slice: &T) -> &Self::Output;
/// Returns a mutable reference to the output at this location, without
/// performing any bounds checking.
#[unstable(feature = "slice_index_methods", issue = "0")]
unsafe fn get_unchecked_mut(self, slice: &mut T) -> &mut Self::Output;
/// Returns a shared reference to the output at this location, panicking
/// if out of bounds.
#[unstable(feature = "slice_index_methods", issue = "0")]
fn index(self, slice: &T) -> &Self::Output;
/// Returns a mutable reference to the output at this location, panicking
/// if out of bounds.
#[unstable(feature = "slice_index_methods", issue = "0")]
fn index_mut(self, slice: &mut T) -> &mut Self::Output;
}
#[stable(feature = "slice-get-slice-impls", since = "1.15.0")]
impl<T> SliceIndex<[T]> for usize {
type Output = T;
#[inline]
fn get(self, slice: &[T]) -> Option<&T> {
if self < slice.len() {
unsafe {
Some(self.get_unchecked(slice))
}
} else {
None
}
}
#[inline]
fn get_mut(self, slice: &mut [T]) -> Option<&mut T> {
if self < slice.len() {
unsafe {
Some(self.get_unchecked_mut(slice))
}
} else {
None
}
}
#[inline]
unsafe fn get_unchecked(self, slice: &[T]) -> &T {
&*slice.as_ptr().offset(self as isize)
}
#[inline]
unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut T {
&mut *slice.as_mut_ptr().offset(self as isize)
}
#[inline]
fn index(self, slice: &[T]) -> &T {
// NB: use intrinsic indexing
&(*slice)[self]
}
#[inline]
fn index_mut(self, slice: &mut [T]) -> &mut T {
// NB: use intrinsic indexing
&mut (*slice)[self]
}
}
#[stable(feature = "slice-get-slice-impls", since = "1.15.0")]
impl<T> SliceIndex<[T]> for ops::Range<usize> {
type Output = [T];
#[inline]
fn get(self, slice: &[T]) -> Option<&[T]> {
if self.start > self.end || self.end > slice.len() {
None
} else {
unsafe {
Some(self.get_unchecked(slice))
}
}
}
#[inline]
fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
if self.start > self.end || self.end > slice.len() {
None
} else {
unsafe {
Some(self.get_unchecked_mut(slice))
}
}
}
#[inline]
unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
from_raw_parts(slice.as_ptr().offset(self.start as isize), self.end - self.start)
}
#[inline]
unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
from_raw_parts_mut(slice.as_mut_ptr().offset(self.start as isize), self.end - self.start)
}
#[inline]
fn index(self, slice: &[T]) -> &[T] {
if self.start > self.end {
slice_index_order_fail(self.start, self.end);
} else if self.end > slice.len() {
slice_index_len_fail(self.end, slice.len());
}
unsafe {
self.get_unchecked(slice)
}
}
#[inline]
fn index_mut(self, slice: &mut [T]) -> &mut [T] {
if self.start > self.end {
slice_index_order_fail(self.start, self.end);
} else if self.end > slice.len() {
slice_index_len_fail(self.end, slice.len());
}
unsafe {
self.get_unchecked_mut(slice)
}
}
}
#[stable(feature = "slice-get-slice-impls", since = "1.15.0")]
impl<T> SliceIndex<[T]> for ops::RangeTo<usize> {
type Output = [T];
#[inline]
fn get(self, slice: &[T]) -> Option<&[T]> {
(0..self.end).get(slice)
}
#[inline]
fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
(0..self.end).get_mut(slice)
}
#[inline]
unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
(0..self.end).get_unchecked(slice)
}
#[inline]
unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
(0..self.end).get_unchecked_mut(slice)
}
#[inline]
fn index(self, slice: &[T]) -> &[T] {
(0..self.end).index(slice)
}
#[inline]
fn index_mut(self, slice: &mut [T]) -> &mut [T] {
(0..self.end).index_mut(slice)
}
}
#[stable(feature = "slice-get-slice-impls", since = "1.15.0")]
impl<T> SliceIndex<[T]> for ops::RangeFrom<usize> {
type Output = [T];
#[inline]
fn get(self, slice: &[T]) -> Option<&[T]> {
(self.start..slice.len()).get(slice)
}
#[inline]
fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
(self.start..slice.len()).get_mut(slice)
}
#[inline]
unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
(self.start..slice.len()).get_unchecked(slice)
}
#[inline]
unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
(self.start..slice.len()).get_unchecked_mut(slice)
}
#[inline]
fn index(self, slice: &[T]) -> &[T] {
(self.start..slice.len()).index(slice)
}
#[inline]
fn index_mut(self, slice: &mut [T]) -> &mut [T] {
(self.start..slice.len()).index_mut(slice)
}
}
#[stable(feature = "slice-get-slice-impls", since = "1.15.0")]
impl<T> SliceIndex<[T]> for ops::RangeFull {
type Output = [T];
#[inline]
fn get(self, slice: &[T]) -> Option<&[T]> {
Some(slice)
}
#[inline]
fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
Some(slice)
}
#[inline]
unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
slice
}
#[inline]
unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
slice
}
#[inline]
fn index(self, slice: &[T]) -> &[T] {
slice
}
#[inline]
fn index_mut(self, slice: &mut [T]) -> &mut [T] {
slice
}
}
#[stable(feature = "inclusive_range", since = "1.26.0")]
impl<T> SliceIndex<[T]> for ops::RangeInclusive<usize> {
type Output = [T];
#[inline]
fn get(self, slice: &[T]) -> Option<&[T]> {
if self.end == usize::max_value() { None }
else { (self.start..self.end + 1).get(slice) }
}
#[inline]
fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
if self.end == usize::max_value() { None }
else { (self.start..self.end + 1).get_mut(slice) }
}
#[inline]
unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
(self.start..self.end + 1).get_unchecked(slice)
}
#[inline]
unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
(self.start..self.end + 1).get_unchecked_mut(slice)
}
#[inline]
fn index(self, slice: &[T]) -> &[T] {
if self.end == usize::max_value() { slice_index_overflow_fail(); }
(self.start..self.end + 1).index(slice)
}
#[inline]
fn index_mut(self, slice: &mut [T]) -> &mut [T] {
if self.end == usize::max_value() { slice_index_overflow_fail(); }
(self.start..self.end + 1).index_mut(slice)
}
}
#[stable(feature = "inclusive_range", since = "1.26.0")]
impl<T> SliceIndex<[T]> for ops::RangeToInclusive<usize> {
type Output = [T];
#[inline]
fn get(self, slice: &[T]) -> Option<&[T]> {
(0..=self.end).get(slice)
}
#[inline]
fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
(0..=self.end).get_mut(slice)
}
#[inline]
unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
(0..=self.end).get_unchecked(slice)
}
#[inline]
unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
(0..=self.end).get_unchecked_mut(slice)
}
#[inline]
fn index(self, slice: &[T]) -> &[T] {
(0..=self.end).index(slice)
}
#[inline]
fn index_mut(self, slice: &mut [T]) -> &mut [T] {
(0..=self.end).index_mut(slice)
}
}
////////////////////////////////////////////////////////////////////////////////
// Common traits
////////////////////////////////////////////////////////////////////////////////
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> Default for &'a [T] {
/// Creates an empty slice.
fn default() -> &'a [T] { &[] }
}
#[stable(feature = "mut_slice_default", since = "1.5.0")]
impl<'a, T> Default for &'a mut [T] {
/// Creates a mutable empty slice.
fn default() -> &'a mut [T] { &mut [] }
}
//
// Iterators
//
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> IntoIterator for &'a [T] {
type Item = &'a T;
type IntoIter = Iter<'a, T>;
fn into_iter(self) -> Iter<'a, T> {
self.iter()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> IntoIterator for &'a mut [T] {
type Item = &'a mut T;
type IntoIter = IterMut<'a, T>;
fn into_iter(self) -> IterMut<'a, T> {
self.iter_mut()
}
}
#[inline]
fn size_from_ptr<T>(_: *const T) -> usize {
mem::size_of::<T>()
}
// The shared definition of the `Iter` and `IterMut` iterators
macro_rules! iterator {
(struct $name:ident -> $ptr:ty, $elem:ty, $mkref:ident) => {
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> Iterator for $name<'a, T> {
type Item = $elem;
#[inline]
fn next(&mut self) -> Option<$elem> {
// could be implemented with slices, but this avoids bounds checks
unsafe {
if mem::size_of::<T>() != 0 {
assume(!self.ptr.is_null());
assume(!self.end.is_null());
}
if self.ptr == self.end {
None
} else {
Some($mkref!(self.ptr.post_inc()))
}
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
let exact = unsafe { ptrdistance(self.ptr, self.end) };
(exact, Some(exact))
}
#[inline]
fn count(self) -> usize {
self.len()
}
#[inline]
fn nth(&mut self, n: usize) -> Option<$elem> {
// Call helper method. Can't put the definition here because mut versus const.
self.iter_nth(n)
}
#[inline]
fn last(mut self) -> Option<$elem> {
self.next_back()
}
#[inline]
fn try_fold<B, F, R>(&mut self, init: B, mut f: F) -> R where
Self: Sized, F: FnMut(B, Self::Item) -> R, R: Try<Ok=B>
{
// manual unrolling is needed when there are conditional exits from the loop
let mut accum = init;
unsafe {
while ptrdistance(self.ptr, self.end) >= 4 {
accum = f(accum, $mkref!(self.ptr.post_inc()))?;
accum = f(accum, $mkref!(self.ptr.post_inc()))?;
accum = f(accum, $mkref!(self.ptr.post_inc()))?;
accum = f(accum, $mkref!(self.ptr.post_inc()))?;
}
while self.ptr != self.end {
accum = f(accum, $mkref!(self.ptr.post_inc()))?;
}
}
Try::from_ok(accum)
}
#[inline]
fn fold<Acc, Fold>(mut self, init: Acc, mut f: Fold) -> Acc
where Fold: FnMut(Acc, Self::Item) -> Acc,
{
// Let LLVM unroll this, rather than using the default
// impl that would force the manual unrolling above
let mut accum = init;
while let Some(x) = self.next() {
accum = f(accum, x);
}
accum
}
#[inline]
#[rustc_inherit_overflow_checks]
fn position<P>(&mut self, mut predicate: P) -> Option<usize> where
Self: Sized,
P: FnMut(Self::Item) -> bool,
{
// The addition might panic on overflow
// Use the len of the slice to hint optimizer to remove result index bounds check.
let n = make_slice!(self.ptr, self.end).len();
self.try_fold(0, move |i, x| {
if predicate(x) { Err(i) }
else { Ok(i + 1) }
}).err()
.map(|i| {
unsafe { assume(i < n) };
i
})
}
#[inline]
fn rposition<P>(&mut self, mut predicate: P) -> Option<usize> where
P: FnMut(Self::Item) -> bool,
Self: Sized + ExactSizeIterator + DoubleEndedIterator
{
// No need for an overflow check here, because `ExactSizeIterator`
// implies that the number of elements fits into a `usize`.
// Use the len of the slice to hint optimizer to remove result index bounds check.
let n = make_slice!(self.ptr, self.end).len();
self.try_rfold(n, move |i, x| {
let i = i - 1;
if predicate(x) { Err(i) }
else { Ok(i) }
}).err()
.map(|i| {
unsafe { assume(i < n) };
i
})
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> DoubleEndedIterator for $name<'a, T> {
#[inline]
fn next_back(&mut self) -> Option<$elem> {
// could be implemented with slices, but this avoids bounds checks
unsafe {
if mem::size_of::<T>() != 0 {
assume(!self.ptr.is_null());
assume(!self.end.is_null());
}
if self.end == self.ptr {
None
} else {
Some($mkref!(self.end.pre_dec()))
}
}
}
#[inline]
fn try_rfold<B, F, R>(&mut self, init: B, mut f: F) -> R where
Self: Sized, F: FnMut(B, Self::Item) -> R, R: Try<Ok=B>
{
// manual unrolling is needed when there are conditional exits from the loop
let mut accum = init;
unsafe {
while ptrdistance(self.ptr, self.end) >= 4 {
accum = f(accum, $mkref!(self.end.pre_dec()))?;
accum = f(accum, $mkref!(self.end.pre_dec()))?;
accum = f(accum, $mkref!(self.end.pre_dec()))?;
accum = f(accum, $mkref!(self.end.pre_dec()))?;
}
while self.ptr != self.end {
accum = f(accum, $mkref!(self.end.pre_dec()))?;
}
}
Try::from_ok(accum)
}
#[inline]
fn rfold<Acc, Fold>(mut self, init: Acc, mut f: Fold) -> Acc
where Fold: FnMut(Acc, Self::Item) -> Acc,
{
// Let LLVM unroll this, rather than using the default
// impl that would force the manual unrolling above
let mut accum = init;
while let Some(x) = self.next_back() {
accum = f(accum, x);
}
accum
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl<'a, T> FusedIterator for $name<'a, T> {}
#[unstable(feature = "trusted_len", issue = "37572")]
unsafe impl<'a, T> TrustedLen for $name<'a, T> {}
}
}
macro_rules! make_slice {
($start: expr, $end: expr) => {{
let start = $start;
let diff = ($end as usize).wrapping_sub(start as usize);
if size_from_ptr(start) == 0 {
// use a non-null pointer value
unsafe { from_raw_parts(1 as *const _, diff) }
} else {
let len = diff / size_from_ptr(start);
unsafe { from_raw_parts(start, len) }
}
}}
}
macro_rules! make_mut_slice {
($start: expr, $end: expr) => {{
let start = $start;
let diff = ($end as usize).wrapping_sub(start as usize);
if size_from_ptr(start) == 0 {
// use a non-null pointer value
unsafe { from_raw_parts_mut(1 as *mut _, diff) }
} else {
let len = diff / size_from_ptr(start);
unsafe { from_raw_parts_mut(start, len) }
}
}}
}
/// Immutable slice iterator
///
/// This struct is created by the [`iter`] method on [slices].
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// // First, we declare a type which has `iter` method to get the `Iter` struct (&[usize here]):
/// let slice = &[1, 2, 3];
///
/// // Then, we iterate over it:
/// for element in slice.iter() {
/// println!("{}", element);
/// }
/// ```
///
/// [`iter`]: ../../std/primitive.slice.html#method.iter
/// [slices]: ../../std/primitive.slice.html
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Iter<'a, T: 'a> {
ptr: *const T,
end: *const T,
_marker: marker::PhantomData<&'a T>,
}
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<'a, T: 'a + fmt::Debug> fmt::Debug for Iter<'a, T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_tuple("Iter")
.field(&self.as_slice())
.finish()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
unsafe impl<'a, T: Sync> Sync for Iter<'a, T> {}
#[stable(feature = "rust1", since = "1.0.0")]
unsafe impl<'a, T: Sync> Send for Iter<'a, T> {}
impl<'a, T> Iter<'a, T> {
/// View the underlying data as a subslice of the original data.
///
/// This has the same lifetime as the original slice, and so the
/// iterator can continue to be used while this exists.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// // First, we declare a type which has the `iter` method to get the `Iter`
/// // struct (&[usize here]):
/// let slice = &[1, 2, 3];
///
/// // Then, we get the iterator:
/// let mut iter = slice.iter();
/// // So if we print what `as_slice` method returns here, we have "[1, 2, 3]":
/// println!("{:?}", iter.as_slice());
///
/// // Next, we move to the second element of the slice:
/// iter.next();
/// // Now `as_slice` returns "[2, 3]":
/// println!("{:?}", iter.as_slice());
/// ```
#[stable(feature = "iter_to_slice", since = "1.4.0")]
pub fn as_slice(&self) -> &'a [T] {
make_slice!(self.ptr, self.end)
}
// Helper function for Iter::nth
fn iter_nth(&mut self, n: usize) -> Option<&'a T> {
match self.as_slice().get(n) {
Some(elem_ref) => unsafe {
self.ptr = slice_offset!(self.ptr, (n as isize).wrapping_add(1));
Some(elem_ref)
},
None => {
self.ptr = self.end;
None
}
}
}
}
iterator!{struct Iter -> *const T, &'a T, make_ref}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> ExactSizeIterator for Iter<'a, T> {
fn is_empty(&self) -> bool {
self.ptr == self.end
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> Clone for Iter<'a, T> {
fn clone(&self) -> Iter<'a, T> { Iter { ptr: self.ptr, end: self.end, _marker: self._marker } }
}
#[stable(feature = "slice_iter_as_ref", since = "1.13.0")]
impl<'a, T> AsRef<[T]> for Iter<'a, T> {
fn as_ref(&self) -> &[T] {
self.as_slice()
}
}
/// Mutable slice iterator.
///
/// This struct is created by the [`iter_mut`] method on [slices].
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// // First, we declare a type which has `iter_mut` method to get the `IterMut`
/// // struct (&[usize here]):
/// let mut slice = &mut [1, 2, 3];
///
/// // Then, we iterate over it and increment each element value:
/// for element in slice.iter_mut() {
/// *element += 1;
/// }
///
/// // We now have "[2, 3, 4]":
/// println!("{:?}", slice);
/// ```
///
/// [`iter_mut`]: ../../std/primitive.slice.html#method.iter_mut
/// [slices]: ../../std/primitive.slice.html
#[stable(feature = "rust1", since = "1.0.0")]
pub struct IterMut<'a, T: 'a> {
ptr: *mut T,
end: *mut T,
_marker: marker::PhantomData<&'a mut T>,
}
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<'a, T: 'a + fmt::Debug> fmt::Debug for IterMut<'a, T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_tuple("IterMut")
.field(&make_slice!(self.ptr, self.end))
.finish()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
unsafe impl<'a, T: Sync> Sync for IterMut<'a, T> {}
#[stable(feature = "rust1", since = "1.0.0")]
unsafe impl<'a, T: Send> Send for IterMut<'a, T> {}
impl<'a, T> IterMut<'a, T> {
/// View the underlying data as a subslice of the original data.
///
/// To avoid creating `&mut` references that alias, this is forced
/// to consume the iterator.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// // First, we declare a type which has `iter_mut` method to get the `IterMut`
/// // struct (&[usize here]):
/// let mut slice = &mut [1, 2, 3];
///
/// {
/// // Then, we get the iterator:
/// let mut iter = slice.iter_mut();
/// // We move to next element:
/// iter.next();
/// // So if we print what `into_slice` method returns here, we have "[2, 3]":
/// println!("{:?}", iter.into_slice());
/// }
///
/// // Now let's modify a value of the slice:
/// {
/// // First we get back the iterator:
/// let mut iter = slice.iter_mut();
/// // We change the value of the first element of the slice returned by the `next` method:
/// *iter.next().unwrap() += 1;
/// }
/// // Now slice is "[2, 2, 3]":
/// println!("{:?}", slice);
/// ```
#[stable(feature = "iter_to_slice", since = "1.4.0")]
pub fn into_slice(self) -> &'a mut [T] {
make_mut_slice!(self.ptr, self.end)
}
// Helper function for IterMut::nth
fn iter_nth(&mut self, n: usize) -> Option<&'a mut T> {
match make_mut_slice!(self.ptr, self.end).get_mut(n) {
Some(elem_ref) => unsafe {
self.ptr = slice_offset!(self.ptr, (n as isize).wrapping_add(1));
Some(elem_ref)
},
None => {
self.ptr = self.end;
None
}
}
}
}
iterator!{struct IterMut -> *mut T, &'a mut T, make_ref_mut}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> ExactSizeIterator for IterMut<'a, T> {
fn is_empty(&self) -> bool {
self.ptr == self.end
}
}
// Return the number of elements of `T` from `start` to `end`.
// Return the arithmetic difference if `T` is zero size.
#[inline(always)]
unsafe fn ptrdistance<T>(start: *const T, end: *const T) -> usize {
if mem::size_of::<T>() == 0 {
(end as usize).wrapping_sub(start as usize)
} else {
end.offset_from(start) as usize
}
}
// Extension methods for raw pointers, used by the iterators
trait PointerExt : Copy {
unsafe fn slice_offset(self, i: isize) -> Self;
/// Increments `self` by 1, but returns the old value.
#[inline(always)]
unsafe fn post_inc(&mut self) -> Self {
let current = *self;
*self = self.slice_offset(1);
current
}
/// Decrements `self` by 1, and returns the new value.
#[inline(always)]
unsafe fn pre_dec(&mut self) -> Self {
*self = self.slice_offset(-1);
*self
}
}
impl<T> PointerExt for *const T {
#[inline(always)]
unsafe fn slice_offset(self, i: isize) -> Self {
slice_offset!(self, i)
}
}
impl<T> PointerExt for *mut T {
#[inline(always)]
unsafe fn slice_offset(self, i: isize) -> Self {
slice_offset!(self, i)
}
}
/// An internal abstraction over the splitting iterators, so that
/// splitn, splitn_mut etc can be implemented once.
#[doc(hidden)]
trait SplitIter: DoubleEndedIterator {
/// Marks the underlying iterator as complete, extracting the remaining
/// portion of the slice.
fn finish(&mut self) -> Option<Self::Item>;
}
/// An iterator over subslices separated by elements that match a predicate
/// function.
///
/// This struct is created by the [`split`] method on [slices].
///
/// [`split`]: ../../std/primitive.slice.html#method.split
/// [slices]: ../../std/primitive.slice.html
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Split<'a, T:'a, P> where P: FnMut(&T) -> bool {
v: &'a [T],
pred: P,
finished: bool
}
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for Split<'a, T, P> where P: FnMut(&T) -> bool {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("Split")
.field("v", &self.v)
.field("finished", &self.finished)
.finish()
}
}
// FIXME(#26925) Remove in favor of `#[derive(Clone)]`
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T, P> Clone for Split<'a, T, P> where P: Clone + FnMut(&T) -> bool {
fn clone(&self) -> Split<'a, T, P> {
Split {
v: self.v,
pred: self.pred.clone(),
finished: self.finished,
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T, P> Iterator for Split<'a, T, P> where P: FnMut(&T) -> bool {
type Item = &'a [T];
#[inline]
fn next(&mut self) -> Option<&'a [T]> {
if self.finished { return None; }
match self.v.iter().position(|x| (self.pred)(x)) {
None => self.finish(),
Some(idx) => {
let ret = Some(&self.v[..idx]);
self.v = &self.v[idx + 1..];
ret
}
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
if self.finished {
(0, Some(0))
} else {
(1, Some(self.v.len() + 1))
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T, P> DoubleEndedIterator for Split<'a, T, P> where P: FnMut(&T) -> bool {
#[inline]
fn next_back(&mut self) -> Option<&'a [T]> {
if self.finished { return None; }
match self.v.iter().rposition(|x| (self.pred)(x)) {
None => self.finish(),
Some(idx) => {
let ret = Some(&self.v[idx + 1..]);
self.v = &self.v[..idx];
ret
}
}
}
}
impl<'a, T, P> SplitIter for Split<'a, T, P> where P: FnMut(&T) -> bool {
#[inline]
fn finish(&mut self) -> Option<&'a [T]> {
if self.finished { None } else { self.finished = true; Some(self.v) }
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl<'a, T, P> FusedIterator for Split<'a, T, P> where P: FnMut(&T) -> bool {}
/// An iterator over the subslices of the vector which are separated
/// by elements that match `pred`.
///
/// This struct is created by the [`split_mut`] method on [slices].
///
/// [`split_mut`]: ../../std/primitive.slice.html#method.split_mut
/// [slices]: ../../std/primitive.slice.html
#[stable(feature = "rust1", since = "1.0.0")]
pub struct SplitMut<'a, T:'a, P> where P: FnMut(&T) -> bool {
v: &'a mut [T],
pred: P,
finished: bool
}
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("SplitMut")
.field("v", &self.v)
.field("finished", &self.finished)
.finish()
}
}
impl<'a, T, P> SplitIter for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {
#[inline]
fn finish(&mut self) -> Option<&'a mut [T]> {
if self.finished {
None
} else {
self.finished = true;
Some(mem::replace(&mut self.v, &mut []))
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T, P> Iterator for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {
type Item = &'a mut [T];
#[inline]
fn next(&mut self) -> Option<&'a mut [T]> {
if self.finished { return None; }
let idx_opt = { // work around borrowck limitations
let pred = &mut self.pred;
self.v.iter().position(|x| (*pred)(x))
};
match idx_opt {
None => self.finish(),
Some(idx) => {
let tmp = mem::replace(&mut self.v, &mut []);
let (head, tail) = tmp.split_at_mut(idx);
self.v = &mut tail[1..];
Some(head)
}
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
if self.finished {
(0, Some(0))
} else {
// if the predicate doesn't match anything, we yield one slice
// if it matches every element, we yield len+1 empty slices.
(1, Some(self.v.len() + 1))
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T, P> DoubleEndedIterator for SplitMut<'a, T, P> where
P: FnMut(&T) -> bool,
{
#[inline]
fn next_back(&mut self) -> Option<&'a mut [T]> {
if self.finished { return None; }
let idx_opt = { // work around borrowck limitations
let pred = &mut self.pred;
self.v.iter().rposition(|x| (*pred)(x))
};
match idx_opt {
None => self.finish(),
Some(idx) => {
let tmp = mem::replace(&mut self.v, &mut []);
let (head, tail) = tmp.split_at_mut(idx);
self.v = head;
Some(&mut tail[1..])
}
}
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl<'a, T, P> FusedIterator for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {}
/// An iterator over subslices separated by elements that match a predicate
/// function, starting from the end of the slice.
///
/// This struct is created by the [`rsplit`] method on [slices].
///
/// [`rsplit`]: ../../std/primitive.slice.html#method.rsplit
/// [slices]: ../../std/primitive.slice.html
#[stable(feature = "slice_rsplit", since = "1.27.0")]
#[derive(Clone)] // Is this correct, or does it incorrectly require `T: Clone`?
pub struct RSplit<'a, T:'a, P> where P: FnMut(&T) -> bool {
inner: Split<'a, T, P>
}
#[stable(feature = "slice_rsplit", since = "1.27.0")]
impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for RSplit<'a, T, P> where P: FnMut(&T) -> bool {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("RSplit")
.field("v", &self.inner.v)
.field("finished", &self.inner.finished)
.finish()
}
}
#[stable(feature = "slice_rsplit", since = "1.27.0")]
impl<'a, T, P> Iterator for RSplit<'a, T, P> where P: FnMut(&T) -> bool {
type Item = &'a [T];
#[inline]
fn next(&mut self) -> Option<&'a [T]> {
self.inner.next_back()
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
}
#[stable(feature = "slice_rsplit", since = "1.27.0")]
impl<'a, T, P> DoubleEndedIterator for RSplit<'a, T, P> where P: FnMut(&T) -> bool {
#[inline]
fn next_back(&mut self) -> Option<&'a [T]> {
self.inner.next()
}
}
#[stable(feature = "slice_rsplit", since = "1.27.0")]
impl<'a, T, P> SplitIter for RSplit<'a, T, P> where P: FnMut(&T) -> bool {
#[inline]
fn finish(&mut self) -> Option<&'a [T]> {
self.inner.finish()
}
}
#[stable(feature = "slice_rsplit", since = "1.27.0")]
impl<'a, T, P> FusedIterator for RSplit<'a, T, P> where P: FnMut(&T) -> bool {}
/// An iterator over the subslices of the vector which are separated
/// by elements that match `pred`, starting from the end of the slice.
///
/// This struct is created by the [`rsplit_mut`] method on [slices].
///
/// [`rsplit_mut`]: ../../std/primitive.slice.html#method.rsplit_mut
/// [slices]: ../../std/primitive.slice.html
#[stable(feature = "slice_rsplit", since = "1.27.0")]
pub struct RSplitMut<'a, T:'a, P> where P: FnMut(&T) -> bool {
inner: SplitMut<'a, T, P>
}
#[stable(feature = "slice_rsplit", since = "1.27.0")]
impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for RSplitMut<'a, T, P> where P: FnMut(&T) -> bool {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("RSplitMut")
.field("v", &self.inner.v)
.field("finished", &self.inner.finished)
.finish()
}
}
#[stable(feature = "slice_rsplit", since = "1.27.0")]
impl<'a, T, P> SplitIter for RSplitMut<'a, T, P> where P: FnMut(&T) -> bool {
#[inline]
fn finish(&mut self) -> Option<&'a mut [T]> {
self.inner.finish()
}
}
#[stable(feature = "slice_rsplit", since = "1.27.0")]
impl<'a, T, P> Iterator for RSplitMut<'a, T, P> where P: FnMut(&T) -> bool {
type Item = &'a mut [T];
#[inline]
fn next(&mut self) -> Option<&'a mut [T]> {
self.inner.next_back()
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
}
#[stable(feature = "slice_rsplit", since = "1.27.0")]
impl<'a, T, P> DoubleEndedIterator for RSplitMut<'a, T, P> where
P: FnMut(&T) -> bool,
{
#[inline]
fn next_back(&mut self) -> Option<&'a mut [T]> {
self.inner.next()
}
}
#[stable(feature = "slice_rsplit", since = "1.27.0")]
impl<'a, T, P> FusedIterator for RSplitMut<'a, T, P> where P: FnMut(&T) -> bool {}
/// An private iterator over subslices separated by elements that
/// match a predicate function, splitting at most a fixed number of
/// times.
#[derive(Debug)]
struct GenericSplitN<I> {
iter: I,
count: usize,
}
impl<T, I: SplitIter<Item=T>> Iterator for GenericSplitN<I> {
type Item = T;
#[inline]
fn next(&mut self) -> Option<T> {
match self.count {
0 => None,
1 => { self.count -= 1; self.iter.finish() }
_ => { self.count -= 1; self.iter.next() }
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
let (lower, upper_opt) = self.iter.size_hint();
(lower, upper_opt.map(|upper| cmp::min(self.count, upper)))
}
}
/// An iterator over subslices separated by elements that match a predicate
/// function, limited to a given number of splits.
///
/// This struct is created by the [`splitn`] method on [slices].
///
/// [`splitn`]: ../../std/primitive.slice.html#method.splitn
/// [slices]: ../../std/primitive.slice.html
#[stable(feature = "rust1", since = "1.0.0")]
pub struct SplitN<'a, T: 'a, P> where P: FnMut(&T) -> bool {
inner: GenericSplitN<Split<'a, T, P>>
}
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for SplitN<'a, T, P> where P: FnMut(&T) -> bool {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("SplitN")
.field("inner", &self.inner)
.finish()
}
}
/// An iterator over subslices separated by elements that match a
/// predicate function, limited to a given number of splits, starting
/// from the end of the slice.
///
/// This struct is created by the [`rsplitn`] method on [slices].
///
/// [`rsplitn`]: ../../std/primitive.slice.html#method.rsplitn
/// [slices]: ../../std/primitive.slice.html
#[stable(feature = "rust1", since = "1.0.0")]
pub struct RSplitN<'a, T: 'a, P> where P: FnMut(&T) -> bool {
inner: GenericSplitN<RSplit<'a, T, P>>
}
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for RSplitN<'a, T, P> where P: FnMut(&T) -> bool {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("RSplitN")
.field("inner", &self.inner)
.finish()
}
}
/// An iterator over subslices separated by elements that match a predicate
/// function, limited to a given number of splits.
///
/// This struct is created by the [`splitn_mut`] method on [slices].
///
/// [`splitn_mut`]: ../../std/primitive.slice.html#method.splitn_mut
/// [slices]: ../../std/primitive.slice.html
#[stable(feature = "rust1", since = "1.0.0")]
pub struct SplitNMut<'a, T: 'a, P> where P: FnMut(&T) -> bool {
inner: GenericSplitN<SplitMut<'a, T, P>>
}
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for SplitNMut<'a, T, P> where P: FnMut(&T) -> bool {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("SplitNMut")
.field("inner", &self.inner)
.finish()
}
}
/// An iterator over subslices separated by elements that match a
/// predicate function, limited to a given number of splits, starting
/// from the end of the slice.
///
/// This struct is created by the [`rsplitn_mut`] method on [slices].
///
/// [`rsplitn_mut`]: ../../std/primitive.slice.html#method.rsplitn_mut
/// [slices]: ../../std/primitive.slice.html
#[stable(feature = "rust1", since = "1.0.0")]
pub struct RSplitNMut<'a, T: 'a, P> where P: FnMut(&T) -> bool {
inner: GenericSplitN<RSplitMut<'a, T, P>>
}
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for RSplitNMut<'a, T, P> where P: FnMut(&T) -> bool {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("RSplitNMut")
.field("inner", &self.inner)
.finish()
}
}
macro_rules! forward_iterator {
($name:ident: $elem:ident, $iter_of:ty) => {
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, $elem, P> Iterator for $name<'a, $elem, P> where
P: FnMut(&T) -> bool
{
type Item = $iter_of;
#[inline]
fn next(&mut self) -> Option<$iter_of> {
self.inner.next()
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl<'a, $elem, P> FusedIterator for $name<'a, $elem, P>
where P: FnMut(&T) -> bool {}
}
}
forward_iterator! { SplitN: T, &'a [T] }
forward_iterator! { RSplitN: T, &'a [T] }
forward_iterator! { SplitNMut: T, &'a mut [T] }
forward_iterator! { RSplitNMut: T, &'a mut [T] }
/// An iterator over overlapping subslices of length `size`.
///
/// This struct is created by the [`windows`] method on [slices].
///
/// [`windows`]: ../../std/primitive.slice.html#method.windows
/// [slices]: ../../std/primitive.slice.html
#[derive(Debug)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Windows<'a, T:'a> {
v: &'a [T],
size: usize
}
// FIXME(#26925) Remove in favor of `#[derive(Clone)]`
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> Clone for Windows<'a, T> {
fn clone(&self) -> Windows<'a, T> {
Windows {
v: self.v,
size: self.size,
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> Iterator for Windows<'a, T> {
type Item = &'a [T];
#[inline]
fn next(&mut self) -> Option<&'a [T]> {
if self.size > self.v.len() {
None
} else {
let ret = Some(&self.v[..self.size]);
self.v = &self.v[1..];
ret
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
if self.size > self.v.len() {
(0, Some(0))
} else {
let size = self.v.len() - self.size + 1;
(size, Some(size))
}
}
#[inline]
fn count(self) -> usize {
self.len()
}
#[inline]
fn nth(&mut self, n: usize) -> Option<Self::Item> {
let (end, overflow) = self.size.overflowing_add(n);
if end > self.v.len() || overflow {
self.v = &[];
None
} else {
let nth = &self.v[n..end];
self.v = &self.v[n+1..];
Some(nth)
}
}
#[inline]
fn last(self) -> Option<Self::Item> {
if self.size > self.v.len() {
None
} else {
let start = self.v.len() - self.size;
Some(&self.v[start..])
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> DoubleEndedIterator for Windows<'a, T> {
#[inline]
fn next_back(&mut self) -> Option<&'a [T]> {
if self.size > self.v.len() {
None
} else {
let ret = Some(&self.v[self.v.len()-self.size..]);
self.v = &self.v[..self.v.len()-1];
ret
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> ExactSizeIterator for Windows<'a, T> {}
#[unstable(feature = "trusted_len", issue = "37572")]
unsafe impl<'a, T> TrustedLen for Windows<'a, T> {}
#[stable(feature = "fused", since = "1.26.0")]
impl<'a, T> FusedIterator for Windows<'a, T> {}
#[doc(hidden)]
unsafe impl<'a, T> TrustedRandomAccess for Windows<'a, T> {
unsafe fn get_unchecked(&mut self, i: usize) -> &'a [T] {
from_raw_parts(self.v.as_ptr().offset(i as isize), self.size)
}
fn may_have_side_effect() -> bool { false }
}
/// An iterator over a slice in (non-overlapping) chunks (`chunk_size` elements at a
/// time).
///
/// When the slice len is not evenly divided by the chunk size, the last slice
/// of the iteration will be the remainder.
///
/// This struct is created by the [`chunks`] method on [slices].
///
/// [`chunks`]: ../../std/primitive.slice.html#method.chunks
/// [slices]: ../../std/primitive.slice.html
#[derive(Debug)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Chunks<'a, T:'a> {
v: &'a [T],
chunk_size: usize
}
// FIXME(#26925) Remove in favor of `#[derive(Clone)]`
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> Clone for Chunks<'a, T> {
fn clone(&self) -> Chunks<'a, T> {
Chunks {
v: self.v,
chunk_size: self.chunk_size,
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> Iterator for Chunks<'a, T> {
type Item = &'a [T];
#[inline]
fn next(&mut self) -> Option<&'a [T]> {
if self.v.is_empty() {
None
} else {
let chunksz = cmp::min(self.v.len(), self.chunk_size);
let (fst, snd) = self.v.split_at(chunksz);
self.v = snd;
Some(fst)
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
if self.v.is_empty() {
(0, Some(0))
} else {
let n = self.v.len() / self.chunk_size;
let rem = self.v.len() % self.chunk_size;
let n = if rem > 0 { n+1 } else { n };
(n, Some(n))
}
}
#[inline]
fn count(self) -> usize {
self.len()
}
#[inline]
fn nth(&mut self, n: usize) -> Option<Self::Item> {
let (start, overflow) = n.overflowing_mul(self.chunk_size);
if start >= self.v.len() || overflow {
self.v = &[];
None
} else {
let end = match start.checked_add(self.chunk_size) {
Some(sum) => cmp::min(self.v.len(), sum),
None => self.v.len(),
};
let nth = &self.v[start..end];
self.v = &self.v[end..];
Some(nth)
}
}
#[inline]
fn last(self) -> Option<Self::Item> {
if self.v.is_empty() {
None
} else {
let start = (self.v.len() - 1) / self.chunk_size * self.chunk_size;
Some(&self.v[start..])
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> DoubleEndedIterator for Chunks<'a, T> {
#[inline]
fn next_back(&mut self) -> Option<&'a [T]> {
if self.v.is_empty() {
None
} else {
let remainder = self.v.len() % self.chunk_size;
let chunksz = if remainder != 0 { remainder } else { self.chunk_size };
let (fst, snd) = self.v.split_at(self.v.len() - chunksz);
self.v = fst;
Some(snd)
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> ExactSizeIterator for Chunks<'a, T> {}
#[unstable(feature = "trusted_len", issue = "37572")]
unsafe impl<'a, T> TrustedLen for Chunks<'a, T> {}
#[stable(feature = "fused", since = "1.26.0")]
impl<'a, T> FusedIterator for Chunks<'a, T> {}
#[doc(hidden)]
unsafe impl<'a, T> TrustedRandomAccess for Chunks<'a, T> {
unsafe fn get_unchecked(&mut self, i: usize) -> &'a [T] {
let start = i * self.chunk_size;
let end = match start.checked_add(self.chunk_size) {
None => self.v.len(),
Some(end) => cmp::min(end, self.v.len()),
};
from_raw_parts(self.v.as_ptr().offset(start as isize), end - start)
}
fn may_have_side_effect() -> bool { false }
}
/// An iterator over a slice in (non-overlapping) mutable chunks (`chunk_size`
/// elements at a time). When the slice len is not evenly divided by the chunk
/// size, the last slice of the iteration will be the remainder.
///
/// This struct is created by the [`chunks_mut`] method on [slices].
///
/// [`chunks_mut`]: ../../std/primitive.slice.html#method.chunks_mut
/// [slices]: ../../std/primitive.slice.html
#[derive(Debug)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct ChunksMut<'a, T:'a> {
v: &'a mut [T],
chunk_size: usize
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> Iterator for ChunksMut<'a, T> {
type Item = &'a mut [T];
#[inline]
fn next(&mut self) -> Option<&'a mut [T]> {
if self.v.is_empty() {
None
} else {
let sz = cmp::min(self.v.len(), self.chunk_size);
let tmp = mem::replace(&mut self.v, &mut []);
let (head, tail) = tmp.split_at_mut(sz);
self.v = tail;
Some(head)
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
if self.v.is_empty() {
(0, Some(0))
} else {
let n = self.v.len() / self.chunk_size;
let rem = self.v.len() % self.chunk_size;
let n = if rem > 0 { n + 1 } else { n };
(n, Some(n))
}
}
#[inline]
fn count(self) -> usize {
self.len()
}
#[inline]
fn nth(&mut self, n: usize) -> Option<&'a mut [T]> {
let (start, overflow) = n.overflowing_mul(self.chunk_size);
if start >= self.v.len() || overflow {
self.v = &mut [];
None
} else {
let end = match start.checked_add(self.chunk_size) {
Some(sum) => cmp::min(self.v.len(), sum),
None => self.v.len(),
};
let tmp = mem::replace(&mut self.v, &mut []);
let (head, tail) = tmp.split_at_mut(end);
let (_, nth) = head.split_at_mut(start);
self.v = tail;
Some(nth)
}
}
#[inline]
fn last(self) -> Option<Self::Item> {
if self.v.is_empty() {
None
} else {
let start = (self.v.len() - 1) / self.chunk_size * self.chunk_size;
Some(&mut self.v[start..])
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> DoubleEndedIterator for ChunksMut<'a, T> {
#[inline]
fn next_back(&mut self) -> Option<&'a mut [T]> {
if self.v.is_empty() {
None
} else {
let remainder = self.v.len() % self.chunk_size;
let sz = if remainder != 0 { remainder } else { self.chunk_size };
let tmp = mem::replace(&mut self.v, &mut []);
let tmp_len = tmp.len();
let (head, tail) = tmp.split_at_mut(tmp_len - sz);
self.v = head;
Some(tail)
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> ExactSizeIterator for ChunksMut<'a, T> {}
#[unstable(feature = "trusted_len", issue = "37572")]
unsafe impl<'a, T> TrustedLen for ChunksMut<'a, T> {}
#[stable(feature = "fused", since = "1.26.0")]
impl<'a, T> FusedIterator for ChunksMut<'a, T> {}
#[doc(hidden)]
unsafe impl<'a, T> TrustedRandomAccess for ChunksMut<'a, T> {
unsafe fn get_unchecked(&mut self, i: usize) -> &'a mut [T] {
let start = i * self.chunk_size;
let end = match start.checked_add(self.chunk_size) {
None => self.v.len(),
Some(end) => cmp::min(end, self.v.len()),
};
from_raw_parts_mut(self.v.as_mut_ptr().offset(start as isize), end - start)
}
fn may_have_side_effect() -> bool { false }
}
/// An iterator over a slice in (non-overlapping) chunks (`chunk_size` elements at a
/// time).
///
/// When the slice len is not evenly divided by the chunk size, the last
/// up to `chunk_size-1` elements will be omitted.
///
/// This struct is created by the [`exact_chunks`] method on [slices].
///
/// [`exact_chunks`]: ../../std/primitive.slice.html#method.exact_chunks
/// [slices]: ../../std/primitive.slice.html
#[derive(Debug)]
#[unstable(feature = "exact_chunks", issue = "47115")]
pub struct ExactChunks<'a, T:'a> {
v: &'a [T],
chunk_size: usize
}
// FIXME(#26925) Remove in favor of `#[derive(Clone)]`
#[unstable(feature = "exact_chunks", issue = "47115")]
impl<'a, T> Clone for ExactChunks<'a, T> {
fn clone(&self) -> ExactChunks<'a, T> {
ExactChunks {
v: self.v,
chunk_size: self.chunk_size,
}
}
}
#[unstable(feature = "exact_chunks", issue = "47115")]
impl<'a, T> Iterator for ExactChunks<'a, T> {
type Item = &'a [T];
#[inline]
fn next(&mut self) -> Option<&'a [T]> {
if self.v.len() < self.chunk_size {
None
} else {
let (fst, snd) = self.v.split_at(self.chunk_size);
self.v = snd;
Some(fst)
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
let n = self.v.len() / self.chunk_size;
(n, Some(n))
}
#[inline]
fn count(self) -> usize {
self.len()
}
#[inline]
fn nth(&mut self, n: usize) -> Option<Self::Item> {
let (start, overflow) = n.overflowing_mul(self.chunk_size);
if start >= self.v.len() || overflow {
self.v = &[];
None
} else {
let (_, snd) = self.v.split_at(start);
self.v = snd;
self.next()
}
}
#[inline]
fn last(mut self) -> Option<Self::Item> {
self.next_back()
}
}
#[unstable(feature = "exact_chunks", issue = "47115")]
impl<'a, T> DoubleEndedIterator for ExactChunks<'a, T> {
#[inline]
fn next_back(&mut self) -> Option<&'a [T]> {
if self.v.len() < self.chunk_size {
None
} else {
let (fst, snd) = self.v.split_at(self.v.len() - self.chunk_size);
self.v = fst;
Some(snd)
}
}
}
#[unstable(feature = "exact_chunks", issue = "47115")]
impl<'a, T> ExactSizeIterator for ExactChunks<'a, T> {
fn is_empty(&self) -> bool {
self.v.is_empty()
}
}
#[unstable(feature = "trusted_len", issue = "37572")]
unsafe impl<'a, T> TrustedLen for ExactChunks<'a, T> {}
#[unstable(feature = "exact_chunks", issue = "47115")]
impl<'a, T> FusedIterator for ExactChunks<'a, T> {}
#[doc(hidden)]
unsafe impl<'a, T> TrustedRandomAccess for ExactChunks<'a, T> {
unsafe fn get_unchecked(&mut self, i: usize) -> &'a [T] {
let start = i * self.chunk_size;
from_raw_parts(self.v.as_ptr().offset(start as isize), self.chunk_size)
}
fn may_have_side_effect() -> bool { false }
}
/// An iterator over a slice in (non-overlapping) mutable chunks (`chunk_size`
/// elements at a time). When the slice len is not evenly divided by the chunk
/// size, the last up to `chunk_size-1` elements will be omitted.
///
/// This struct is created by the [`exact_chunks_mut`] method on [slices].
///
/// [`exact_chunks_mut`]: ../../std/primitive.slice.html#method.exact_chunks_mut
/// [slices]: ../../std/primitive.slice.html
#[derive(Debug)]
#[unstable(feature = "exact_chunks", issue = "47115")]
pub struct ExactChunksMut<'a, T:'a> {
v: &'a mut [T],
chunk_size: usize
}
#[unstable(feature = "exact_chunks", issue = "47115")]
impl<'a, T> Iterator for ExactChunksMut<'a, T> {
type Item = &'a mut [T];
#[inline]
fn next(&mut self) -> Option<&'a mut [T]> {
if self.v.len() < self.chunk_size {
None
} else {
let tmp = mem::replace(&mut self.v, &mut []);
let (head, tail) = tmp.split_at_mut(self.chunk_size);
self.v = tail;
Some(head)
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
let n = self.v.len() / self.chunk_size;
(n, Some(n))
}
#[inline]
fn count(self) -> usize {
self.len()
}
#[inline]
fn nth(&mut self, n: usize) -> Option<&'a mut [T]> {
let (start, overflow) = n.overflowing_mul(self.chunk_size);
if start >= self.v.len() || overflow {
self.v = &mut [];
None
} else {
let tmp = mem::replace(&mut self.v, &mut []);
let (_, snd) = tmp.split_at_mut(start);
self.v = snd;
self.next()
}
}
#[inline]
fn last(mut self) -> Option<Self::Item> {
self.next_back()
}
}
#[unstable(feature = "exact_chunks", issue = "47115")]
impl<'a, T> DoubleEndedIterator for ExactChunksMut<'a, T> {
#[inline]
fn next_back(&mut self) -> Option<&'a mut [T]> {
if self.v.len() < self.chunk_size {
None
} else {
let tmp = mem::replace(&mut self.v, &mut []);
let tmp_len = tmp.len();
let (head, tail) = tmp.split_at_mut(tmp_len - self.chunk_size);
self.v = head;
Some(tail)
}
}
}
#[unstable(feature = "exact_chunks", issue = "47115")]
impl<'a, T> ExactSizeIterator for ExactChunksMut<'a, T> {
fn is_empty(&self) -> bool {
self.v.is_empty()
}
}
#[unstable(feature = "trusted_len", issue = "37572")]
unsafe impl<'a, T> TrustedLen for ExactChunksMut<'a, T> {}
#[unstable(feature = "exact_chunks", issue = "47115")]
impl<'a, T> FusedIterator for ExactChunksMut<'a, T> {}
#[doc(hidden)]
unsafe impl<'a, T> TrustedRandomAccess for ExactChunksMut<'a, T> {
unsafe fn get_unchecked(&mut self, i: usize) -> &'a mut [T] {
let start = i * self.chunk_size;
from_raw_parts_mut(self.v.as_mut_ptr().offset(start as isize), self.chunk_size)
}
fn may_have_side_effect() -> bool { false }
}
//
// Free functions
//
/// Forms a slice from a pointer and a length.
///
/// The `len` argument is the number of **elements**, not the number of bytes.
///
/// # Safety
///
/// This function is unsafe as there is no guarantee that the given pointer is
/// valid for `len` elements, nor whether the lifetime inferred is a suitable
/// lifetime for the returned slice.
///
/// `data` must be non-null and aligned, even for zero-length slices. One
/// reason for this is that enum layout optimizations may rely on references
/// (including slices of any length) being aligned and non-null to distinguish
/// them from other data. You can obtain a pointer that is usable as `data`
/// for zero-length slices using [`NonNull::dangling()`].
///
/// # Caveat
///
/// The lifetime for the returned slice is inferred from its usage. To
/// prevent accidental misuse, it's suggested to tie the lifetime to whichever
/// source lifetime is safe in the context, such as by providing a helper
/// function taking the lifetime of a host value for the slice, or by explicit
/// annotation.
///
/// # Examples
///
/// ```
/// use std::slice;
///
/// // manifest a slice out of thin air!
/// let ptr = 0x1234 as *const usize;
/// let amt = 10;
/// unsafe {
/// let slice = slice::from_raw_parts(ptr, amt);
/// }
/// ```
///
/// [`NonNull::dangling()`]: ../../std/ptr/struct.NonNull.html#method.dangling
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub unsafe fn from_raw_parts<'a, T>(data: *const T, len: usize) -> &'a [T] {
Repr { raw: FatPtr { data, len } }.rust
}
/// Performs the same functionality as `from_raw_parts`, except that a mutable
/// slice is returned.
///
/// This function is unsafe for the same reasons as `from_raw_parts`, as well
/// as not being able to provide a non-aliasing guarantee of the returned
/// mutable slice. `data` must be non-null and aligned even for zero-length
/// slices as with `from_raw_parts`.
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub unsafe fn from_raw_parts_mut<'a, T>(data: *mut T, len: usize) -> &'a mut [T] {
Repr { raw: FatPtr { data, len} }.rust_mut
}
/// Converts a reference to T into a slice of length 1 (without copying).
#[stable(feature = "from_ref", since = "1.28.0")]
pub fn from_ref<T>(s: &T) -> &[T] {
unsafe {
from_raw_parts(s, 1)
}
}
/// Converts a reference to T into a slice of length 1 (without copying).
#[stable(feature = "from_ref", since = "1.28.0")]
pub fn from_mut<T>(s: &mut T) -> &mut [T] {
unsafe {
from_raw_parts_mut(s, 1)
}
}
// This function is public only because there is no other way to unit test heapsort.
#[unstable(feature = "sort_internals", reason = "internal to sort module", issue = "0")]
#[doc(hidden)]
pub fn heapsort<T, F>(v: &mut [T], mut is_less: F)
where F: FnMut(&T, &T) -> bool
{
sort::heapsort(v, &mut is_less);
}
//
// Comparison traits
//
extern {
/// Calls implementation provided memcmp.
///
/// Interprets the data as u8.
///
/// Returns 0 for equal, < 0 for less than and > 0 for greater
/// than.
// FIXME(#32610): Return type should be c_int
fn memcmp(s1: *const u8, s2: *const u8, n: usize) -> i32;
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<A, B> PartialEq<[B]> for [A] where A: PartialEq<B> {
fn eq(&self, other: &[B]) -> bool {
SlicePartialEq::equal(self, other)
}
fn ne(&self, other: &[B]) -> bool {
SlicePartialEq::not_equal(self, other)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<T: Eq> Eq for [T] {}
/// Implements comparison of vectors lexicographically.
#[stable(feature = "rust1", since = "1.0.0")]
impl<T: Ord> Ord for [T] {
fn cmp(&self, other: &[T]) -> Ordering {
SliceOrd::compare(self, other)
}
}
/// Implements comparison of vectors lexicographically.
#[stable(feature = "rust1", since = "1.0.0")]
impl<T: PartialOrd> PartialOrd for [T] {
fn partial_cmp(&self, other: &[T]) -> Option<Ordering> {
SlicePartialOrd::partial_compare(self, other)
}
}
#[doc(hidden)]
// intermediate trait for specialization of slice's PartialEq
trait SlicePartialEq<B> {
fn equal(&self, other: &[B]) -> bool;
fn not_equal(&self, other: &[B]) -> bool { !self.equal(other) }
}
// Generic slice equality
impl<A, B> SlicePartialEq<B> for [A]
where A: PartialEq<B>
{
default fn equal(&self, other: &[B]) -> bool {
if self.len() != other.len() {
return false;
}
for i in 0..self.len() {
if !self[i].eq(&other[i]) {
return false;
}
}
true
}
}
// Use memcmp for bytewise equality when the types allow
impl<A> SlicePartialEq<A> for [A]
where A: PartialEq<A> + BytewiseEquality
{
fn equal(&self, other: &[A]) -> bool {
if self.len() != other.len() {
return false;
}
if self.as_ptr() == other.as_ptr() {
return true;
}
unsafe {
let size = mem::size_of_val(self);
memcmp(self.as_ptr() as *const u8,
other.as_ptr() as *const u8, size) == 0
}
}
}
#[doc(hidden)]
// intermediate trait for specialization of slice's PartialOrd
trait SlicePartialOrd<B> {
fn partial_compare(&self, other: &[B]) -> Option<Ordering>;
}
impl<A> SlicePartialOrd<A> for [A]
where A: PartialOrd
{
default fn partial_compare(&self, other: &[A]) -> Option<Ordering> {
let l = cmp::min(self.len(), other.len());
// Slice to the loop iteration range to enable bound check
// elimination in the compiler
let lhs = &self[..l];
let rhs = &other[..l];
for i in 0..l {
match lhs[i].partial_cmp(&rhs[i]) {
Some(Ordering::Equal) => (),
non_eq => return non_eq,
}
}
self.len().partial_cmp(&other.len())
}
}
impl<A> SlicePartialOrd<A> for [A]
where A: Ord
{
default fn partial_compare(&self, other: &[A]) -> Option<Ordering> {
Some(SliceOrd::compare(self, other))
}
}
#[doc(hidden)]
// intermediate trait for specialization of slice's Ord
trait SliceOrd<B> {
fn compare(&self, other: &[B]) -> Ordering;
}
impl<A> SliceOrd<A> for [A]
where A: Ord
{
default fn compare(&self, other: &[A]) -> Ordering {
let l = cmp::min(self.len(), other.len());
// Slice to the loop iteration range to enable bound check
// elimination in the compiler
let lhs = &self[..l];
let rhs = &other[..l];
for i in 0..l {
match lhs[i].cmp(&rhs[i]) {
Ordering::Equal => (),
non_eq => return non_eq,
}
}
self.len().cmp(&other.len())
}
}
// memcmp compares a sequence of unsigned bytes lexicographically.
// this matches the order we want for [u8], but no others (not even [i8]).
impl SliceOrd<u8> for [u8] {
#[inline]
fn compare(&self, other: &[u8]) -> Ordering {
let order = unsafe {
memcmp(self.as_ptr(), other.as_ptr(),
cmp::min(self.len(), other.len()))
};
if order == 0 {
self.len().cmp(&other.len())
} else if order < 0 {
Less
} else {
Greater
}
}
}
#[doc(hidden)]
/// Trait implemented for types that can be compared for equality using
/// their bytewise representation
trait BytewiseEquality { }
macro_rules! impl_marker_for {
($traitname:ident, $($ty:ty)*) => {
$(
impl $traitname for $ty { }
)*
}
}
impl_marker_for!(BytewiseEquality,
u8 i8 u16 i16 u32 i32 u64 i64 usize isize char bool);
#[doc(hidden)]
unsafe impl<'a, T> TrustedRandomAccess for Iter<'a, T> {
unsafe fn get_unchecked(&mut self, i: usize) -> &'a T {
&*self.ptr.offset(i as isize)
}
fn may_have_side_effect() -> bool { false }
}
#[doc(hidden)]
unsafe impl<'a, T> TrustedRandomAccess for IterMut<'a, T> {
unsafe fn get_unchecked(&mut self, i: usize) -> &'a mut T {
&mut *self.ptr.offset(i as isize)
}
fn may_have_side_effect() -> bool { false }
}
trait SliceContains: Sized {
fn slice_contains(&self, x: &[Self]) -> bool;
}
impl<T> SliceContains for T where T: PartialEq {
default fn slice_contains(&self, x: &[Self]) -> bool {
x.iter().any(|y| *y == *self)
}
}
impl SliceContains for u8 {
fn slice_contains(&self, x: &[Self]) -> bool {
memchr::memchr(*self, x).is_some()
}
}
impl SliceContains for i8 {
fn slice_contains(&self, x: &[Self]) -> bool {
let byte = *self as u8;
let bytes: &[u8] = unsafe { from_raw_parts(x.as_ptr() as *const u8, x.len()) };
memchr::memchr(byte, bytes).is_some()
}
}
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