1 // Copyright 2012-2017 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! Slice management and manipulation
13 //! For more details see [`std::slice`].
15 //! [`std::slice`]: ../../std/slice/index.html
17 #![stable(feature = "rust1", since = "1.0.0")]
19 // How this module is organized.
21 // The library infrastructure for slices is fairly messy. There's
22 // a lot of stuff defined here. Let's keep it clean.
24 // Since slices don't support inherent methods; all operations
25 // on them are defined on traits, which are then re-exported from
26 // the prelude for convenience. So there are a lot of traits here.
28 // The layout of this file is thus:
30 // * Slice-specific 'extension' traits and their implementations. This
31 // is where most of the slice API resides.
32 // * Implementations of a few common traits with important slice ops.
33 // * Definitions of a bunch of iterators.
35 // * The `raw` and `bytes` submodules.
36 // * Boilerplate trait implementations.
38 use cmp::Ordering::{self, Less, Equal, Greater};
41 use intrinsics::assume;
43 use ops::{FnMut, Try, self};
45 use option::Option::{None, Some};
47 use result::Result::{Ok, Err};
50 use marker::{Copy, Send, Sync, Sized, self};
51 use iter_private::TrustedRandomAccess;
53 #[unstable(feature = "slice_internals", issue = "0",
54 reason = "exposed from core to be reused in std; use the memchr crate")]
55 /// Pure rust memchr implementation, taken from rust-memchr
62 union Repr<'a, T: 'a> {
64 rust_mut: &'a mut [T],
81 /// Returns the number of elements in the slice.
86 /// let a = [1, 2, 3];
87 /// assert_eq!(a.len(), 3);
89 #[stable(feature = "rust1", since = "1.0.0")]
91 #[rustc_const_unstable(feature = "const_slice_len")]
92 pub const fn len(&self) -> usize {
94 Repr { rust: self }.raw.len
98 /// Returns `true` if the slice has a length of 0.
103 /// let a = [1, 2, 3];
104 /// assert!(!a.is_empty());
106 #[stable(feature = "rust1", since = "1.0.0")]
108 #[rustc_const_unstable(feature = "const_slice_len")]
109 pub const fn is_empty(&self) -> bool {
113 /// Returns the first element of the slice, or `None` if it is empty.
118 /// let v = [10, 40, 30];
119 /// assert_eq!(Some(&10), v.first());
121 /// let w: &[i32] = &[];
122 /// assert_eq!(None, w.first());
124 #[stable(feature = "rust1", since = "1.0.0")]
126 pub fn first(&self) -> Option<&T> {
127 if self.is_empty() { None } else { Some(&self[0]) }
130 /// Returns a mutable pointer to the first element of the slice, or `None` if it is empty.
135 /// let x = &mut [0, 1, 2];
137 /// if let Some(first) = x.first_mut() {
140 /// assert_eq!(x, &[5, 1, 2]);
142 #[stable(feature = "rust1", since = "1.0.0")]
144 pub fn first_mut(&mut self) -> Option<&mut T> {
145 if self.is_empty() { None } else { Some(&mut self[0]) }
148 /// Returns the first and all the rest of the elements of the slice, or `None` if it is empty.
153 /// let x = &[0, 1, 2];
155 /// if let Some((first, elements)) = x.split_first() {
156 /// assert_eq!(first, &0);
157 /// assert_eq!(elements, &[1, 2]);
160 #[stable(feature = "slice_splits", since = "1.5.0")]
162 pub fn split_first(&self) -> Option<(&T, &[T])> {
163 if self.is_empty() { None } else { Some((&self[0], &self[1..])) }
166 /// Returns the first and all the rest of the elements of the slice, or `None` if it is empty.
171 /// let x = &mut [0, 1, 2];
173 /// if let Some((first, elements)) = x.split_first_mut() {
178 /// assert_eq!(x, &[3, 4, 5]);
180 #[stable(feature = "slice_splits", since = "1.5.0")]
182 pub fn split_first_mut(&mut self) -> Option<(&mut T, &mut [T])> {
183 if self.is_empty() { None } else {
184 let split = self.split_at_mut(1);
185 Some((&mut split.0[0], split.1))
189 /// Returns the last and all the rest of the elements of the slice, or `None` if it is empty.
194 /// let x = &[0, 1, 2];
196 /// if let Some((last, elements)) = x.split_last() {
197 /// assert_eq!(last, &2);
198 /// assert_eq!(elements, &[0, 1]);
201 #[stable(feature = "slice_splits", since = "1.5.0")]
203 pub fn split_last(&self) -> Option<(&T, &[T])> {
204 let len = self.len();
205 if len == 0 { None } else { Some((&self[len - 1], &self[..(len - 1)])) }
208 /// Returns the last and all the rest of the elements of the slice, or `None` if it is empty.
213 /// let x = &mut [0, 1, 2];
215 /// if let Some((last, elements)) = x.split_last_mut() {
220 /// assert_eq!(x, &[4, 5, 3]);
222 #[stable(feature = "slice_splits", since = "1.5.0")]
224 pub fn split_last_mut(&mut self) -> Option<(&mut T, &mut [T])> {
225 let len = self.len();
226 if len == 0 { None } else {
227 let split = self.split_at_mut(len - 1);
228 Some((&mut split.1[0], split.0))
233 /// Returns the last element of the slice, or `None` if it is empty.
238 /// let v = [10, 40, 30];
239 /// assert_eq!(Some(&30), v.last());
241 /// let w: &[i32] = &[];
242 /// assert_eq!(None, w.last());
244 #[stable(feature = "rust1", since = "1.0.0")]
246 pub fn last(&self) -> Option<&T> {
247 if self.is_empty() { None } else { Some(&self[self.len() - 1]) }
250 /// Returns a mutable pointer to the last item in the slice.
255 /// let x = &mut [0, 1, 2];
257 /// if let Some(last) = x.last_mut() {
260 /// assert_eq!(x, &[0, 1, 10]);
262 #[stable(feature = "rust1", since = "1.0.0")]
264 pub fn last_mut(&mut self) -> Option<&mut T> {
265 let len = self.len();
266 if len == 0 { return None; }
267 Some(&mut self[len - 1])
270 /// Returns a reference to an element or subslice depending on the type of
273 /// - If given a position, returns a reference to the element at that
274 /// position or `None` if out of bounds.
275 /// - If given a range, returns the subslice corresponding to that range,
276 /// or `None` if out of bounds.
281 /// let v = [10, 40, 30];
282 /// assert_eq!(Some(&40), v.get(1));
283 /// assert_eq!(Some(&[10, 40][..]), v.get(0..2));
284 /// assert_eq!(None, v.get(3));
285 /// assert_eq!(None, v.get(0..4));
287 #[stable(feature = "rust1", since = "1.0.0")]
289 pub fn get<I>(&self, index: I) -> Option<&I::Output>
290 where I: SliceIndex<Self>
295 /// Returns a mutable reference to an element or subslice depending on the
296 /// type of index (see [`get`]) or `None` if the index is out of bounds.
298 /// [`get`]: #method.get
303 /// let x = &mut [0, 1, 2];
305 /// if let Some(elem) = x.get_mut(1) {
308 /// assert_eq!(x, &[0, 42, 2]);
310 #[stable(feature = "rust1", since = "1.0.0")]
312 pub fn get_mut<I>(&mut self, index: I) -> Option<&mut I::Output>
313 where I: SliceIndex<Self>
318 /// Returns a reference to an element or subslice, without doing bounds
321 /// This is generally not recommended, use with caution! For a safe
322 /// alternative see [`get`].
324 /// [`get`]: #method.get
329 /// let x = &[1, 2, 4];
332 /// assert_eq!(x.get_unchecked(1), &2);
335 #[stable(feature = "rust1", since = "1.0.0")]
337 pub unsafe fn get_unchecked<I>(&self, index: I) -> &I::Output
338 where I: SliceIndex<Self>
340 index.get_unchecked(self)
343 /// Returns a mutable reference to an element or subslice, without doing
346 /// This is generally not recommended, use with caution! For a safe
347 /// alternative see [`get_mut`].
349 /// [`get_mut`]: #method.get_mut
354 /// let x = &mut [1, 2, 4];
357 /// let elem = x.get_unchecked_mut(1);
360 /// assert_eq!(x, &[1, 13, 4]);
362 #[stable(feature = "rust1", since = "1.0.0")]
364 pub unsafe fn get_unchecked_mut<I>(&mut self, index: I) -> &mut I::Output
365 where I: SliceIndex<Self>
367 index.get_unchecked_mut(self)
370 /// Returns a raw pointer to the slice's buffer.
372 /// The caller must ensure that the slice outlives the pointer this
373 /// function returns, or else it will end up pointing to garbage.
375 /// Modifying the container referenced by this slice may cause its buffer
376 /// to be reallocated, which would also make any pointers to it invalid.
381 /// let x = &[1, 2, 4];
382 /// let x_ptr = x.as_ptr();
385 /// for i in 0..x.len() {
386 /// assert_eq!(x.get_unchecked(i), &*x_ptr.offset(i as isize));
390 #[stable(feature = "rust1", since = "1.0.0")]
392 #[rustc_const_unstable(feature = "const_slice_as_ptr")]
393 pub const fn as_ptr(&self) -> *const T {
394 self as *const [T] as *const T
397 /// Returns an unsafe mutable pointer to the slice's buffer.
399 /// The caller must ensure that the slice outlives the pointer this
400 /// function returns, or else it will end up pointing to garbage.
402 /// Modifying the container referenced by this slice may cause its buffer
403 /// to be reallocated, which would also make any pointers to it invalid.
408 /// let x = &mut [1, 2, 4];
409 /// let x_ptr = x.as_mut_ptr();
412 /// for i in 0..x.len() {
413 /// *x_ptr.offset(i as isize) += 2;
416 /// assert_eq!(x, &[3, 4, 6]);
418 #[stable(feature = "rust1", since = "1.0.0")]
420 pub fn as_mut_ptr(&mut self) -> *mut T {
421 self as *mut [T] as *mut T
424 /// Swaps two elements in the slice.
428 /// * a - The index of the first element
429 /// * b - The index of the second element
433 /// Panics if `a` or `b` are out of bounds.
438 /// let mut v = ["a", "b", "c", "d"];
440 /// assert!(v == ["a", "d", "c", "b"]);
442 #[stable(feature = "rust1", since = "1.0.0")]
444 pub fn swap(&mut self, a: usize, b: usize) {
446 // Can't take two mutable loans from one vector, so instead just cast
447 // them to their raw pointers to do the swap
448 let pa: *mut T = &mut self[a];
449 let pb: *mut T = &mut self[b];
454 /// Reverses the order of elements in the slice, in place.
459 /// let mut v = [1, 2, 3];
461 /// assert!(v == [3, 2, 1]);
463 #[stable(feature = "rust1", since = "1.0.0")]
465 pub fn reverse(&mut self) {
466 let mut i: usize = 0;
469 // For very small types, all the individual reads in the normal
470 // path perform poorly. We can do better, given efficient unaligned
471 // load/store, by loading a larger chunk and reversing a register.
473 // Ideally LLVM would do this for us, as it knows better than we do
474 // whether unaligned reads are efficient (since that changes between
475 // different ARM versions, for example) and what the best chunk size
476 // would be. Unfortunately, as of LLVM 4.0 (2017-05) it only unrolls
477 // the loop, so we need to do this ourselves. (Hypothesis: reverse
478 // is troublesome because the sides can be aligned differently --
479 // will be, when the length is odd -- so there's no way of emitting
480 // pre- and postludes to use fully-aligned SIMD in the middle.)
483 cfg!(any(target_arch = "x86", target_arch = "x86_64"));
485 if fast_unaligned && mem::size_of::<T>() == 1 {
486 // Use the llvm.bswap intrinsic to reverse u8s in a usize
487 let chunk = mem::size_of::<usize>();
488 while i + chunk - 1 < ln / 2 {
490 let pa: *mut T = self.get_unchecked_mut(i);
491 let pb: *mut T = self.get_unchecked_mut(ln - i - chunk);
492 let va = ptr::read_unaligned(pa as *mut usize);
493 let vb = ptr::read_unaligned(pb as *mut usize);
494 ptr::write_unaligned(pa as *mut usize, vb.swap_bytes());
495 ptr::write_unaligned(pb as *mut usize, va.swap_bytes());
501 if fast_unaligned && mem::size_of::<T>() == 2 {
502 // Use rotate-by-16 to reverse u16s in a u32
503 let chunk = mem::size_of::<u32>() / 2;
504 while i + chunk - 1 < ln / 2 {
506 let pa: *mut T = self.get_unchecked_mut(i);
507 let pb: *mut T = self.get_unchecked_mut(ln - i - chunk);
508 let va = ptr::read_unaligned(pa as *mut u32);
509 let vb = ptr::read_unaligned(pb as *mut u32);
510 ptr::write_unaligned(pa as *mut u32, vb.rotate_left(16));
511 ptr::write_unaligned(pb as *mut u32, va.rotate_left(16));
518 // Unsafe swap to avoid the bounds check in safe swap.
520 let pa: *mut T = self.get_unchecked_mut(i);
521 let pb: *mut T = self.get_unchecked_mut(ln - i - 1);
528 /// Returns an iterator over the slice.
533 /// let x = &[1, 2, 4];
534 /// let mut iterator = x.iter();
536 /// assert_eq!(iterator.next(), Some(&1));
537 /// assert_eq!(iterator.next(), Some(&2));
538 /// assert_eq!(iterator.next(), Some(&4));
539 /// assert_eq!(iterator.next(), None);
541 #[stable(feature = "rust1", since = "1.0.0")]
543 pub fn iter(&self) -> Iter<T> {
545 let ptr = self.as_ptr();
546 assume(!ptr.is_null());
548 let end = if mem::size_of::<T>() == 0 {
549 (ptr as *const u8).wrapping_offset(self.len() as isize) as *const T
551 ptr.offset(self.len() as isize)
557 _marker: marker::PhantomData
562 /// Returns an iterator that allows modifying each value.
567 /// let x = &mut [1, 2, 4];
568 /// for elem in x.iter_mut() {
571 /// assert_eq!(x, &[3, 4, 6]);
573 #[stable(feature = "rust1", since = "1.0.0")]
575 pub fn iter_mut(&mut self) -> IterMut<T> {
577 let ptr = self.as_mut_ptr();
578 assume(!ptr.is_null());
580 let end = if mem::size_of::<T>() == 0 {
581 (ptr as *mut u8).wrapping_offset(self.len() as isize) as *mut T
583 ptr.offset(self.len() as isize)
589 _marker: marker::PhantomData
594 /// Returns an iterator over all contiguous windows of length
595 /// `size`. The windows overlap. If the slice is shorter than
596 /// `size`, the iterator returns no values.
600 /// Panics if `size` is 0.
605 /// let slice = ['r', 'u', 's', 't'];
606 /// let mut iter = slice.windows(2);
607 /// assert_eq!(iter.next().unwrap(), &['r', 'u']);
608 /// assert_eq!(iter.next().unwrap(), &['u', 's']);
609 /// assert_eq!(iter.next().unwrap(), &['s', 't']);
610 /// assert!(iter.next().is_none());
613 /// If the slice is shorter than `size`:
616 /// let slice = ['f', 'o', 'o'];
617 /// let mut iter = slice.windows(4);
618 /// assert!(iter.next().is_none());
620 #[stable(feature = "rust1", since = "1.0.0")]
622 pub fn windows(&self, size: usize) -> Windows<T> {
624 Windows { v: self, size: size }
627 /// Returns an iterator over `chunk_size` elements of the slice at a
628 /// time. The chunks are slices and do not overlap. If `chunk_size` does
629 /// not divide the length of the slice, then the last chunk will
630 /// not have length `chunk_size`.
632 /// See [`exact_chunks`] for a variant of this iterator that returns chunks
633 /// of always exactly `chunk_size` elements.
637 /// Panics if `chunk_size` is 0.
642 /// let slice = ['l', 'o', 'r', 'e', 'm'];
643 /// let mut iter = slice.chunks(2);
644 /// assert_eq!(iter.next().unwrap(), &['l', 'o']);
645 /// assert_eq!(iter.next().unwrap(), &['r', 'e']);
646 /// assert_eq!(iter.next().unwrap(), &['m']);
647 /// assert!(iter.next().is_none());
650 /// [`exact_chunks`]: #method.exact_chunks
651 #[stable(feature = "rust1", since = "1.0.0")]
653 pub fn chunks(&self, chunk_size: usize) -> Chunks<T> {
654 assert!(chunk_size != 0);
655 Chunks { v: self, chunk_size: chunk_size }
658 /// Returns an iterator over `chunk_size` elements of the slice at a time.
659 /// The chunks are mutable slices, and do not overlap. If `chunk_size` does
660 /// not divide the length of the slice, then the last chunk will not
661 /// have length `chunk_size`.
663 /// See [`exact_chunks_mut`] for a variant of this iterator that returns chunks
664 /// of always exactly `chunk_size` elements.
668 /// Panics if `chunk_size` is 0.
673 /// let v = &mut [0, 0, 0, 0, 0];
674 /// let mut count = 1;
676 /// for chunk in v.chunks_mut(2) {
677 /// for elem in chunk.iter_mut() {
682 /// assert_eq!(v, &[1, 1, 2, 2, 3]);
685 /// [`exact_chunks_mut`]: #method.exact_chunks_mut
686 #[stable(feature = "rust1", since = "1.0.0")]
688 pub fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<T> {
689 assert!(chunk_size != 0);
690 ChunksMut { v: self, chunk_size: chunk_size }
693 /// Returns an iterator over `chunk_size` elements of the slice at a
694 /// time. The chunks are slices and do not overlap. If `chunk_size` does
695 /// not divide the length of the slice, then the last up to `chunk_size-1`
696 /// elements will be omitted and can be retrieved from the `remainder`
697 /// function of the iterator.
699 /// Due to each chunk having exactly `chunk_size` elements, the compiler
700 /// can often optimize the resulting code better than in the case of
705 /// Panics if `chunk_size` is 0.
710 /// #![feature(exact_chunks)]
712 /// let slice = ['l', 'o', 'r', 'e', 'm'];
713 /// let mut iter = slice.exact_chunks(2);
714 /// assert_eq!(iter.next().unwrap(), &['l', 'o']);
715 /// assert_eq!(iter.next().unwrap(), &['r', 'e']);
716 /// assert!(iter.next().is_none());
719 /// [`chunks`]: #method.chunks
720 #[unstable(feature = "exact_chunks", issue = "47115")]
722 pub fn exact_chunks(&self, chunk_size: usize) -> ExactChunks<T> {
723 assert!(chunk_size != 0);
724 let rem = self.len() % chunk_size;
725 let len = self.len() - rem;
726 let (fst, snd) = self.split_at(len);
727 ExactChunks { v: fst, rem: snd, chunk_size: chunk_size}
730 /// Returns an iterator over `chunk_size` elements of the slice at a time.
731 /// The chunks are mutable slices, and do not overlap. If `chunk_size` does
732 /// not divide the length of the slice, then the last up to `chunk_size-1`
733 /// elements will be omitted and can be retrieved from the `into_remainder`
734 /// function of the iterator.
736 /// Due to each chunk having exactly `chunk_size` elements, the compiler
737 /// can often optimize the resulting code better than in the case of
742 /// Panics if `chunk_size` is 0.
747 /// #![feature(exact_chunks)]
749 /// let v = &mut [0, 0, 0, 0, 0];
750 /// let mut count = 1;
752 /// for chunk in v.exact_chunks_mut(2) {
753 /// for elem in chunk.iter_mut() {
758 /// assert_eq!(v, &[1, 1, 2, 2, 0]);
761 /// [`chunks_mut`]: #method.chunks_mut
762 #[unstable(feature = "exact_chunks", issue = "47115")]
764 pub fn exact_chunks_mut(&mut self, chunk_size: usize) -> ExactChunksMut<T> {
765 assert!(chunk_size != 0);
766 let rem = self.len() % chunk_size;
767 let len = self.len() - rem;
768 let (fst, snd) = self.split_at_mut(len);
769 ExactChunksMut { v: fst, rem: snd, chunk_size: chunk_size}
772 /// Divides one slice into two at an index.
774 /// The first will contain all indices from `[0, mid)` (excluding
775 /// the index `mid` itself) and the second will contain all
776 /// indices from `[mid, len)` (excluding the index `len` itself).
780 /// Panics if `mid > len`.
785 /// let v = [1, 2, 3, 4, 5, 6];
788 /// let (left, right) = v.split_at(0);
789 /// assert!(left == []);
790 /// assert!(right == [1, 2, 3, 4, 5, 6]);
794 /// let (left, right) = v.split_at(2);
795 /// assert!(left == [1, 2]);
796 /// assert!(right == [3, 4, 5, 6]);
800 /// let (left, right) = v.split_at(6);
801 /// assert!(left == [1, 2, 3, 4, 5, 6]);
802 /// assert!(right == []);
805 #[stable(feature = "rust1", since = "1.0.0")]
807 pub fn split_at(&self, mid: usize) -> (&[T], &[T]) {
808 (&self[..mid], &self[mid..])
811 /// Divides one mutable slice into two at an index.
813 /// The first will contain all indices from `[0, mid)` (excluding
814 /// the index `mid` itself) and the second will contain all
815 /// indices from `[mid, len)` (excluding the index `len` itself).
819 /// Panics if `mid > len`.
824 /// let mut v = [1, 0, 3, 0, 5, 6];
825 /// // scoped to restrict the lifetime of the borrows
827 /// let (left, right) = v.split_at_mut(2);
828 /// assert!(left == [1, 0]);
829 /// assert!(right == [3, 0, 5, 6]);
833 /// assert!(v == [1, 2, 3, 4, 5, 6]);
835 #[stable(feature = "rust1", since = "1.0.0")]
837 pub fn split_at_mut(&mut self, mid: usize) -> (&mut [T], &mut [T]) {
838 let len = self.len();
839 let ptr = self.as_mut_ptr();
844 (from_raw_parts_mut(ptr, mid),
845 from_raw_parts_mut(ptr.offset(mid as isize), len - mid))
849 /// Returns an iterator over subslices separated by elements that match
850 /// `pred`. The matched element is not contained in the subslices.
855 /// let slice = [10, 40, 33, 20];
856 /// let mut iter = slice.split(|num| num % 3 == 0);
858 /// assert_eq!(iter.next().unwrap(), &[10, 40]);
859 /// assert_eq!(iter.next().unwrap(), &[20]);
860 /// assert!(iter.next().is_none());
863 /// If the first element is matched, an empty slice will be the first item
864 /// returned by the iterator. Similarly, if the last element in the slice
865 /// is matched, an empty slice will be the last item returned by the
869 /// let slice = [10, 40, 33];
870 /// let mut iter = slice.split(|num| num % 3 == 0);
872 /// assert_eq!(iter.next().unwrap(), &[10, 40]);
873 /// assert_eq!(iter.next().unwrap(), &[]);
874 /// assert!(iter.next().is_none());
877 /// If two matched elements are directly adjacent, an empty slice will be
878 /// present between them:
881 /// let slice = [10, 6, 33, 20];
882 /// let mut iter = slice.split(|num| num % 3 == 0);
884 /// assert_eq!(iter.next().unwrap(), &[10]);
885 /// assert_eq!(iter.next().unwrap(), &[]);
886 /// assert_eq!(iter.next().unwrap(), &[20]);
887 /// assert!(iter.next().is_none());
889 #[stable(feature = "rust1", since = "1.0.0")]
891 pub fn split<F>(&self, pred: F) -> Split<T, F>
892 where F: FnMut(&T) -> bool
901 /// Returns an iterator over mutable subslices separated by elements that
902 /// match `pred`. The matched element is not contained in the subslices.
907 /// let mut v = [10, 40, 30, 20, 60, 50];
909 /// for group in v.split_mut(|num| *num % 3 == 0) {
912 /// assert_eq!(v, [1, 40, 30, 1, 60, 1]);
914 #[stable(feature = "rust1", since = "1.0.0")]
916 pub fn split_mut<F>(&mut self, pred: F) -> SplitMut<T, F>
917 where F: FnMut(&T) -> bool
919 SplitMut { v: self, pred: pred, finished: false }
922 /// Returns an iterator over subslices separated by elements that match
923 /// `pred`, starting at the end of the slice and working backwards.
924 /// The matched element is not contained in the subslices.
929 /// let slice = [11, 22, 33, 0, 44, 55];
930 /// let mut iter = slice.rsplit(|num| *num == 0);
932 /// assert_eq!(iter.next().unwrap(), &[44, 55]);
933 /// assert_eq!(iter.next().unwrap(), &[11, 22, 33]);
934 /// assert_eq!(iter.next(), None);
937 /// As with `split()`, if the first or last element is matched, an empty
938 /// slice will be the first (or last) item returned by the iterator.
941 /// let v = &[0, 1, 1, 2, 3, 5, 8];
942 /// let mut it = v.rsplit(|n| *n % 2 == 0);
943 /// assert_eq!(it.next().unwrap(), &[]);
944 /// assert_eq!(it.next().unwrap(), &[3, 5]);
945 /// assert_eq!(it.next().unwrap(), &[1, 1]);
946 /// assert_eq!(it.next().unwrap(), &[]);
947 /// assert_eq!(it.next(), None);
949 #[stable(feature = "slice_rsplit", since = "1.27.0")]
951 pub fn rsplit<F>(&self, pred: F) -> RSplit<T, F>
952 where F: FnMut(&T) -> bool
954 RSplit { inner: self.split(pred) }
957 /// Returns an iterator over mutable subslices separated by elements that
958 /// match `pred`, starting at the end of the slice and working
959 /// backwards. The matched element is not contained in the subslices.
964 /// let mut v = [100, 400, 300, 200, 600, 500];
966 /// let mut count = 0;
967 /// for group in v.rsplit_mut(|num| *num % 3 == 0) {
969 /// group[0] = count;
971 /// assert_eq!(v, [3, 400, 300, 2, 600, 1]);
974 #[stable(feature = "slice_rsplit", since = "1.27.0")]
976 pub fn rsplit_mut<F>(&mut self, pred: F) -> RSplitMut<T, F>
977 where F: FnMut(&T) -> bool
979 RSplitMut { inner: self.split_mut(pred) }
982 /// Returns an iterator over subslices separated by elements that match
983 /// `pred`, limited to returning at most `n` items. The matched element is
984 /// not contained in the subslices.
986 /// The last element returned, if any, will contain the remainder of the
991 /// Print the slice split once by numbers divisible by 3 (i.e. `[10, 40]`,
995 /// let v = [10, 40, 30, 20, 60, 50];
997 /// for group in v.splitn(2, |num| *num % 3 == 0) {
998 /// println!("{:?}", group);
1001 #[stable(feature = "rust1", since = "1.0.0")]
1003 pub fn splitn<F>(&self, n: usize, pred: F) -> SplitN<T, F>
1004 where F: FnMut(&T) -> bool
1007 inner: GenericSplitN {
1008 iter: self.split(pred),
1014 /// Returns an iterator over subslices separated by elements that match
1015 /// `pred`, limited to returning at most `n` items. The matched element is
1016 /// not contained in the subslices.
1018 /// The last element returned, if any, will contain the remainder of the
1024 /// let mut v = [10, 40, 30, 20, 60, 50];
1026 /// for group in v.splitn_mut(2, |num| *num % 3 == 0) {
1029 /// assert_eq!(v, [1, 40, 30, 1, 60, 50]);
1031 #[stable(feature = "rust1", since = "1.0.0")]
1033 pub fn splitn_mut<F>(&mut self, n: usize, pred: F) -> SplitNMut<T, F>
1034 where F: FnMut(&T) -> bool
1037 inner: GenericSplitN {
1038 iter: self.split_mut(pred),
1044 /// Returns an iterator over subslices separated by elements that match
1045 /// `pred` limited to returning at most `n` items. This starts at the end of
1046 /// the slice and works backwards. The matched element is not contained in
1049 /// The last element returned, if any, will contain the remainder of the
1054 /// Print the slice split once, starting from the end, by numbers divisible
1055 /// by 3 (i.e. `[50]`, `[10, 40, 30, 20]`):
1058 /// let v = [10, 40, 30, 20, 60, 50];
1060 /// for group in v.rsplitn(2, |num| *num % 3 == 0) {
1061 /// println!("{:?}", group);
1064 #[stable(feature = "rust1", since = "1.0.0")]
1066 pub fn rsplitn<F>(&self, n: usize, pred: F) -> RSplitN<T, F>
1067 where F: FnMut(&T) -> bool
1070 inner: GenericSplitN {
1071 iter: self.rsplit(pred),
1077 /// Returns an iterator over subslices separated by elements that match
1078 /// `pred` limited to returning at most `n` items. This starts at the end of
1079 /// the slice and works backwards. The matched element is not contained in
1082 /// The last element returned, if any, will contain the remainder of the
1088 /// let mut s = [10, 40, 30, 20, 60, 50];
1090 /// for group in s.rsplitn_mut(2, |num| *num % 3 == 0) {
1093 /// assert_eq!(s, [1, 40, 30, 20, 60, 1]);
1095 #[stable(feature = "rust1", since = "1.0.0")]
1097 pub fn rsplitn_mut<F>(&mut self, n: usize, pred: F) -> RSplitNMut<T, F>
1098 where F: FnMut(&T) -> bool
1101 inner: GenericSplitN {
1102 iter: self.rsplit_mut(pred),
1108 /// Returns `true` if the slice contains an element with the given value.
1113 /// let v = [10, 40, 30];
1114 /// assert!(v.contains(&30));
1115 /// assert!(!v.contains(&50));
1117 #[stable(feature = "rust1", since = "1.0.0")]
1118 pub fn contains(&self, x: &T) -> bool
1121 x.slice_contains(self)
1124 /// Returns `true` if `needle` is a prefix of the slice.
1129 /// let v = [10, 40, 30];
1130 /// assert!(v.starts_with(&[10]));
1131 /// assert!(v.starts_with(&[10, 40]));
1132 /// assert!(!v.starts_with(&[50]));
1133 /// assert!(!v.starts_with(&[10, 50]));
1136 /// Always returns `true` if `needle` is an empty slice:
1139 /// let v = &[10, 40, 30];
1140 /// assert!(v.starts_with(&[]));
1141 /// let v: &[u8] = &[];
1142 /// assert!(v.starts_with(&[]));
1144 #[stable(feature = "rust1", since = "1.0.0")]
1145 pub fn starts_with(&self, needle: &[T]) -> bool
1148 let n = needle.len();
1149 self.len() >= n && needle == &self[..n]
1152 /// Returns `true` if `needle` is a suffix of the slice.
1157 /// let v = [10, 40, 30];
1158 /// assert!(v.ends_with(&[30]));
1159 /// assert!(v.ends_with(&[40, 30]));
1160 /// assert!(!v.ends_with(&[50]));
1161 /// assert!(!v.ends_with(&[50, 30]));
1164 /// Always returns `true` if `needle` is an empty slice:
1167 /// let v = &[10, 40, 30];
1168 /// assert!(v.ends_with(&[]));
1169 /// let v: &[u8] = &[];
1170 /// assert!(v.ends_with(&[]));
1172 #[stable(feature = "rust1", since = "1.0.0")]
1173 pub fn ends_with(&self, needle: &[T]) -> bool
1176 let (m, n) = (self.len(), needle.len());
1177 m >= n && needle == &self[m-n..]
1180 /// Binary searches this sorted slice for a given element.
1182 /// If the value is found then `Ok` is returned, containing the
1183 /// index of the matching element; if the value is not found then
1184 /// `Err` is returned, containing the index where a matching
1185 /// element could be inserted while maintaining sorted order.
1189 /// Looks up a series of four elements. The first is found, with a
1190 /// uniquely determined position; the second and third are not
1191 /// found; the fourth could match any position in `[1, 4]`.
1194 /// let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
1196 /// assert_eq!(s.binary_search(&13), Ok(9));
1197 /// assert_eq!(s.binary_search(&4), Err(7));
1198 /// assert_eq!(s.binary_search(&100), Err(13));
1199 /// let r = s.binary_search(&1);
1200 /// assert!(match r { Ok(1..=4) => true, _ => false, });
1202 #[stable(feature = "rust1", since = "1.0.0")]
1203 pub fn binary_search(&self, x: &T) -> Result<usize, usize>
1206 self.binary_search_by(|p| p.cmp(x))
1209 /// Binary searches this sorted slice with a comparator function.
1211 /// The comparator function should implement an order consistent
1212 /// with the sort order of the underlying slice, returning an
1213 /// order code that indicates whether its argument is `Less`,
1214 /// `Equal` or `Greater` the desired target.
1216 /// If a matching value is found then returns `Ok`, containing
1217 /// the index for the matched element; if no match is found then
1218 /// `Err` is returned, containing the index where a matching
1219 /// element could be inserted while maintaining sorted order.
1223 /// Looks up a series of four elements. The first is found, with a
1224 /// uniquely determined position; the second and third are not
1225 /// found; the fourth could match any position in `[1, 4]`.
1228 /// let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
1231 /// assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Ok(9));
1233 /// assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(7));
1235 /// assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(13));
1237 /// let r = s.binary_search_by(|probe| probe.cmp(&seek));
1238 /// assert!(match r { Ok(1..=4) => true, _ => false, });
1240 #[stable(feature = "rust1", since = "1.0.0")]
1242 pub fn binary_search_by<'a, F>(&'a self, mut f: F) -> Result<usize, usize>
1243 where F: FnMut(&'a T) -> Ordering
1246 let mut size = s.len();
1250 let mut base = 0usize;
1252 let half = size / 2;
1253 let mid = base + half;
1254 // mid is always in [0, size), that means mid is >= 0 and < size.
1255 // mid >= 0: by definition
1256 // mid < size: mid = size / 2 + size / 4 + size / 8 ...
1257 let cmp = f(unsafe { s.get_unchecked(mid) });
1258 base = if cmp == Greater { base } else { mid };
1261 // base is always in [0, size) because base <= mid.
1262 let cmp = f(unsafe { s.get_unchecked(base) });
1263 if cmp == Equal { Ok(base) } else { Err(base + (cmp == Less) as usize) }
1267 /// Binary searches this sorted slice with a key extraction function.
1269 /// Assumes that the slice is sorted by the key, for instance with
1270 /// [`sort_by_key`] using the same key extraction function.
1272 /// If a matching value is found then returns `Ok`, containing the
1273 /// index for the matched element; if no match is found then `Err`
1274 /// is returned, containing the index where a matching element could
1275 /// be inserted while maintaining sorted order.
1277 /// [`sort_by_key`]: #method.sort_by_key
1281 /// Looks up a series of four elements in a slice of pairs sorted by
1282 /// their second elements. The first is found, with a uniquely
1283 /// determined position; the second and third are not found; the
1284 /// fourth could match any position in `[1, 4]`.
1287 /// let s = [(0, 0), (2, 1), (4, 1), (5, 1), (3, 1),
1288 /// (1, 2), (2, 3), (4, 5), (5, 8), (3, 13),
1289 /// (1, 21), (2, 34), (4, 55)];
1291 /// assert_eq!(s.binary_search_by_key(&13, |&(a,b)| b), Ok(9));
1292 /// assert_eq!(s.binary_search_by_key(&4, |&(a,b)| b), Err(7));
1293 /// assert_eq!(s.binary_search_by_key(&100, |&(a,b)| b), Err(13));
1294 /// let r = s.binary_search_by_key(&1, |&(a,b)| b);
1295 /// assert!(match r { Ok(1..=4) => true, _ => false, });
1297 #[stable(feature = "slice_binary_search_by_key", since = "1.10.0")]
1299 pub fn binary_search_by_key<'a, B, F>(&'a self, b: &B, mut f: F) -> Result<usize, usize>
1300 where F: FnMut(&'a T) -> B,
1303 self.binary_search_by(|k| f(k).cmp(b))
1306 /// Sorts the slice, but may not preserve the order of equal elements.
1308 /// This sort is unstable (i.e. may reorder equal elements), in-place (i.e. does not allocate),
1309 /// and `O(n log n)` worst-case.
1311 /// # Current implementation
1313 /// The current algorithm is based on [pattern-defeating quicksort][pdqsort] by Orson Peters,
1314 /// which combines the fast average case of randomized quicksort with the fast worst case of
1315 /// heapsort, while achieving linear time on slices with certain patterns. It uses some
1316 /// randomization to avoid degenerate cases, but with a fixed seed to always provide
1317 /// deterministic behavior.
1319 /// It is typically faster than stable sorting, except in a few special cases, e.g. when the
1320 /// slice consists of several concatenated sorted sequences.
1325 /// let mut v = [-5, 4, 1, -3, 2];
1327 /// v.sort_unstable();
1328 /// assert!(v == [-5, -3, 1, 2, 4]);
1331 /// [pdqsort]: https://github.com/orlp/pdqsort
1332 #[stable(feature = "sort_unstable", since = "1.20.0")]
1334 pub fn sort_unstable(&mut self)
1337 sort::quicksort(self, |a, b| a.lt(b));
1340 /// Sorts the slice with a comparator function, but may not preserve the order of equal
1343 /// This sort is unstable (i.e. may reorder equal elements), in-place (i.e. does not allocate),
1344 /// and `O(n log n)` worst-case.
1346 /// # Current implementation
1348 /// The current algorithm is based on [pattern-defeating quicksort][pdqsort] by Orson Peters,
1349 /// which combines the fast average case of randomized quicksort with the fast worst case of
1350 /// heapsort, while achieving linear time on slices with certain patterns. It uses some
1351 /// randomization to avoid degenerate cases, but with a fixed seed to always provide
1352 /// deterministic behavior.
1354 /// It is typically faster than stable sorting, except in a few special cases, e.g. when the
1355 /// slice consists of several concatenated sorted sequences.
1360 /// let mut v = [5, 4, 1, 3, 2];
1361 /// v.sort_unstable_by(|a, b| a.cmp(b));
1362 /// assert!(v == [1, 2, 3, 4, 5]);
1364 /// // reverse sorting
1365 /// v.sort_unstable_by(|a, b| b.cmp(a));
1366 /// assert!(v == [5, 4, 3, 2, 1]);
1369 /// [pdqsort]: https://github.com/orlp/pdqsort
1370 #[stable(feature = "sort_unstable", since = "1.20.0")]
1372 pub fn sort_unstable_by<F>(&mut self, mut compare: F)
1373 where F: FnMut(&T, &T) -> Ordering
1375 sort::quicksort(self, |a, b| compare(a, b) == Ordering::Less);
1378 /// Sorts the slice with a key extraction function, but may not preserve the order of equal
1381 /// This sort is unstable (i.e. may reorder equal elements), in-place (i.e. does not allocate),
1382 /// and `O(m n log(m n))` worst-case, where the key function is `O(m)`.
1384 /// # Current implementation
1386 /// The current algorithm is based on [pattern-defeating quicksort][pdqsort] by Orson Peters,
1387 /// which combines the fast average case of randomized quicksort with the fast worst case of
1388 /// heapsort, while achieving linear time on slices with certain patterns. It uses some
1389 /// randomization to avoid degenerate cases, but with a fixed seed to always provide
1390 /// deterministic behavior.
1395 /// let mut v = [-5i32, 4, 1, -3, 2];
1397 /// v.sort_unstable_by_key(|k| k.abs());
1398 /// assert!(v == [1, 2, -3, 4, -5]);
1401 /// [pdqsort]: https://github.com/orlp/pdqsort
1402 #[stable(feature = "sort_unstable", since = "1.20.0")]
1404 pub fn sort_unstable_by_key<K, F>(&mut self, mut f: F)
1405 where F: FnMut(&T) -> K, K: Ord
1407 sort::quicksort(self, |a, b| f(a).lt(&f(b)));
1410 /// Rotates the slice in-place such that the first `mid` elements of the
1411 /// slice move to the end while the last `self.len() - mid` elements move to
1412 /// the front. After calling `rotate_left`, the element previously at index
1413 /// `mid` will become the first element in the slice.
1417 /// This function will panic if `mid` is greater than the length of the
1418 /// slice. Note that `mid == self.len()` does _not_ panic and is a no-op
1423 /// Takes linear (in `self.len()`) time.
1428 /// let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
1429 /// a.rotate_left(2);
1430 /// assert_eq!(a, ['c', 'd', 'e', 'f', 'a', 'b']);
1433 /// Rotating a subslice:
1436 /// let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
1437 /// a[1..5].rotate_left(1);
1438 /// assert_eq!(a, ['a', 'c', 'd', 'e', 'b', 'f']);
1440 #[stable(feature = "slice_rotate", since = "1.26.0")]
1441 pub fn rotate_left(&mut self, mid: usize) {
1442 assert!(mid <= self.len());
1443 let k = self.len() - mid;
1446 let p = self.as_mut_ptr();
1447 rotate::ptr_rotate(mid, p.offset(mid as isize), k);
1451 /// Rotates the slice in-place such that the first `self.len() - k`
1452 /// elements of the slice move to the end while the last `k` elements move
1453 /// to the front. After calling `rotate_right`, the element previously at
1454 /// index `self.len() - k` will become the first element in the slice.
1458 /// This function will panic if `k` is greater than the length of the
1459 /// slice. Note that `k == self.len()` does _not_ panic and is a no-op
1464 /// Takes linear (in `self.len()`) time.
1469 /// let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
1470 /// a.rotate_right(2);
1471 /// assert_eq!(a, ['e', 'f', 'a', 'b', 'c', 'd']);
1474 /// Rotate a subslice:
1477 /// let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
1478 /// a[1..5].rotate_right(1);
1479 /// assert_eq!(a, ['a', 'e', 'b', 'c', 'd', 'f']);
1481 #[stable(feature = "slice_rotate", since = "1.26.0")]
1482 pub fn rotate_right(&mut self, k: usize) {
1483 assert!(k <= self.len());
1484 let mid = self.len() - k;
1487 let p = self.as_mut_ptr();
1488 rotate::ptr_rotate(mid, p.offset(mid as isize), k);
1492 /// Copies the elements from `src` into `self`.
1494 /// The length of `src` must be the same as `self`.
1496 /// If `src` implements `Copy`, it can be more performant to use
1497 /// [`copy_from_slice`].
1501 /// This function will panic if the two slices have different lengths.
1505 /// Cloning two elements from a slice into another:
1508 /// let src = [1, 2, 3, 4];
1509 /// let mut dst = [0, 0];
1511 /// // Because the slices have to be the same length,
1512 /// // we slice the source slice from four elements
1513 /// // to two. It will panic if we don't do this.
1514 /// dst.clone_from_slice(&src[2..]);
1516 /// assert_eq!(src, [1, 2, 3, 4]);
1517 /// assert_eq!(dst, [3, 4]);
1520 /// Rust enforces that there can only be one mutable reference with no
1521 /// immutable references to a particular piece of data in a particular
1522 /// scope. Because of this, attempting to use `clone_from_slice` on a
1523 /// single slice will result in a compile failure:
1526 /// let mut slice = [1, 2, 3, 4, 5];
1528 /// slice[..2].clone_from_slice(&slice[3..]); // compile fail!
1531 /// To work around this, we can use [`split_at_mut`] to create two distinct
1532 /// sub-slices from a slice:
1535 /// let mut slice = [1, 2, 3, 4, 5];
1538 /// let (left, right) = slice.split_at_mut(2);
1539 /// left.clone_from_slice(&right[1..]);
1542 /// assert_eq!(slice, [4, 5, 3, 4, 5]);
1545 /// [`copy_from_slice`]: #method.copy_from_slice
1546 /// [`split_at_mut`]: #method.split_at_mut
1547 #[stable(feature = "clone_from_slice", since = "1.7.0")]
1548 pub fn clone_from_slice(&mut self, src: &[T]) where T: Clone {
1549 assert!(self.len() == src.len(),
1550 "destination and source slices have different lengths");
1551 // NOTE: We need to explicitly slice them to the same length
1552 // for bounds checking to be elided, and the optimizer will
1553 // generate memcpy for simple cases (for example T = u8).
1554 let len = self.len();
1555 let src = &src[..len];
1557 self[i].clone_from(&src[i]);
1562 /// Copies all elements from `src` into `self`, using a memcpy.
1564 /// The length of `src` must be the same as `self`.
1566 /// If `src` does not implement `Copy`, use [`clone_from_slice`].
1570 /// This function will panic if the two slices have different lengths.
1574 /// Copying two elements from a slice into another:
1577 /// let src = [1, 2, 3, 4];
1578 /// let mut dst = [0, 0];
1580 /// // Because the slices have to be the same length,
1581 /// // we slice the source slice from four elements
1582 /// // to two. It will panic if we don't do this.
1583 /// dst.copy_from_slice(&src[2..]);
1585 /// assert_eq!(src, [1, 2, 3, 4]);
1586 /// assert_eq!(dst, [3, 4]);
1589 /// Rust enforces that there can only be one mutable reference with no
1590 /// immutable references to a particular piece of data in a particular
1591 /// scope. Because of this, attempting to use `copy_from_slice` on a
1592 /// single slice will result in a compile failure:
1595 /// let mut slice = [1, 2, 3, 4, 5];
1597 /// slice[..2].copy_from_slice(&slice[3..]); // compile fail!
1600 /// To work around this, we can use [`split_at_mut`] to create two distinct
1601 /// sub-slices from a slice:
1604 /// let mut slice = [1, 2, 3, 4, 5];
1607 /// let (left, right) = slice.split_at_mut(2);
1608 /// left.copy_from_slice(&right[1..]);
1611 /// assert_eq!(slice, [4, 5, 3, 4, 5]);
1614 /// [`clone_from_slice`]: #method.clone_from_slice
1615 /// [`split_at_mut`]: #method.split_at_mut
1616 #[stable(feature = "copy_from_slice", since = "1.9.0")]
1617 pub fn copy_from_slice(&mut self, src: &[T]) where T: Copy {
1618 assert_eq!(self.len(), src.len(),
1619 "destination and source slices have different lengths");
1621 ptr::copy_nonoverlapping(
1622 src.as_ptr(), self.as_mut_ptr(), self.len());
1626 /// Swaps all elements in `self` with those in `other`.
1628 /// The length of `other` must be the same as `self`.
1632 /// This function will panic if the two slices have different lengths.
1636 /// Swapping two elements across slices:
1639 /// let mut slice1 = [0, 0];
1640 /// let mut slice2 = [1, 2, 3, 4];
1642 /// slice1.swap_with_slice(&mut slice2[2..]);
1644 /// assert_eq!(slice1, [3, 4]);
1645 /// assert_eq!(slice2, [1, 2, 0, 0]);
1648 /// Rust enforces that there can only be one mutable reference to a
1649 /// particular piece of data in a particular scope. Because of this,
1650 /// attempting to use `swap_with_slice` on a single slice will result in
1651 /// a compile failure:
1654 /// let mut slice = [1, 2, 3, 4, 5];
1655 /// slice[..2].swap_with_slice(&mut slice[3..]); // compile fail!
1658 /// To work around this, we can use [`split_at_mut`] to create two distinct
1659 /// mutable sub-slices from a slice:
1662 /// let mut slice = [1, 2, 3, 4, 5];
1665 /// let (left, right) = slice.split_at_mut(2);
1666 /// left.swap_with_slice(&mut right[1..]);
1669 /// assert_eq!(slice, [4, 5, 3, 1, 2]);
1672 /// [`split_at_mut`]: #method.split_at_mut
1673 #[stable(feature = "swap_with_slice", since = "1.27.0")]
1674 pub fn swap_with_slice(&mut self, other: &mut [T]) {
1675 assert!(self.len() == other.len(),
1676 "destination and source slices have different lengths");
1678 ptr::swap_nonoverlapping(
1679 self.as_mut_ptr(), other.as_mut_ptr(), self.len());
1683 /// Function to calculate lenghts of the middle and trailing slice for `align_to{,_mut}`.
1684 fn align_to_offsets<U>(&self) -> (usize, usize) {
1685 // What we gonna do about `rest` is figure out what multiple of `U`s we can put in a
1686 // lowest number of `T`s. And how many `T`s we need for each such "multiple".
1688 // Consider for example T=u8 U=u16. Then we can put 1 U in 2 Ts. Simple. Now, consider
1689 // for example a case where size_of::<T> = 16, size_of::<U> = 24. We can put 2 Us in
1690 // place of every 3 Ts in the `rest` slice. A bit more complicated.
1692 // Formula to calculate this is:
1694 // Us = lcm(size_of::<T>, size_of::<U>) / size_of::<U>
1695 // Ts = lcm(size_of::<T>, size_of::<U>) / size_of::<T>
1697 // Expanded and simplified:
1699 // Us = size_of::<T> / gcd(size_of::<T>, size_of::<U>)
1700 // Ts = size_of::<U> / gcd(size_of::<T>, size_of::<U>)
1702 // Luckily since all this is constant-evaluated... performance here matters not!
1704 fn gcd(a: usize, b: usize) -> usize {
1705 // iterative stein’s algorithm
1706 // We should still make this `const fn` (and revert to recursive algorithm if we do)
1707 // because relying on llvm to consteval all this is… well, it makes me
1708 let (ctz_a, mut ctz_b) = unsafe {
1709 if a == 0 { return b; }
1710 if b == 0 { return a; }
1711 (::intrinsics::cttz_nonzero(a), ::intrinsics::cttz_nonzero(b))
1713 let k = ctz_a.min(ctz_b);
1714 let mut a = a >> ctz_a;
1717 // remove all factors of 2 from b
1720 ::mem::swap(&mut a, &mut b);
1727 ctz_b = ::intrinsics::cttz_nonzero(b);
1732 let gcd: usize = gcd(::mem::size_of::<T>(), ::mem::size_of::<U>());
1733 let ts: usize = ::mem::size_of::<U>() / gcd;
1734 let us: usize = ::mem::size_of::<T>() / gcd;
1736 // Armed with this knowledge, we can find how many `U`s we can fit!
1737 let us_len = self.len() / ts * us;
1738 // And how many `T`s will be in the trailing slice!
1739 let ts_len = self.len() % ts;
1740 return (us_len, ts_len);
1743 /// Transmute the slice to a slice of another type, ensuring aligment of the types is
1746 /// This method splits the slice into three distinct slices: prefix, correctly aligned middle
1747 /// slice of a new type, and the suffix slice. The middle slice will have the greatest length
1748 /// possible for a given type and input slice.
1750 /// This method has no purpose when either input element `T` or output element `U` are
1751 /// zero-sized and will return the original slice without splitting anything.
1755 /// This method is essentially a `transmute` with respect to the elements in the returned
1756 /// middle slice, so all the usual caveats pertaining to `transmute::<T, U>` also apply here.
1763 /// # #![feature(slice_align_to)]
1765 /// let bytes: [u8; 7] = [1, 2, 3, 4, 5, 6, 7];
1766 /// let (prefix, shorts, suffix) = bytes.align_to::<u16>();
1767 /// // less_efficient_algorithm_for_bytes(prefix);
1768 /// // more_efficient_algorithm_for_aligned_shorts(shorts);
1769 /// // less_efficient_algorithm_for_bytes(suffix);
1772 #[unstable(feature = "slice_align_to", issue = "44488")]
1773 pub unsafe fn align_to<U>(&self) -> (&[T], &[U], &[T]) {
1774 // Note that most of this function will be constant-evaluated,
1775 if ::mem::size_of::<U>() == 0 || ::mem::size_of::<T>() == 0 {
1776 // handle ZSTs specially, which is – don't handle them at all.
1777 return (self, &[], &[]);
1780 // First, find at what point do we split between the first and 2nd slice. Easy with
1781 // ptr.align_offset.
1782 let ptr = self.as_ptr();
1783 let offset = ::ptr::align_offset(ptr, ::mem::align_of::<U>());
1784 if offset > self.len() {
1785 return (self, &[], &[]);
1787 let (left, rest) = self.split_at(offset);
1788 let (us_len, ts_len) = rest.align_to_offsets::<U>();
1790 from_raw_parts(rest.as_ptr() as *const U, us_len),
1791 from_raw_parts(rest.as_ptr().offset((rest.len() - ts_len) as isize), ts_len))
1795 /// Transmute the slice to a slice of another type, ensuring aligment of the types is
1798 /// This method splits the slice into three distinct slices: prefix, correctly aligned middle
1799 /// slice of a new type, and the suffix slice. The middle slice will have the greatest length
1800 /// possible for a given type and input slice.
1802 /// This method has no purpose when either input element `T` or output element `U` are
1803 /// zero-sized and will return the original slice without splitting anything.
1807 /// This method is essentially a `transmute` with respect to the elements in the returned
1808 /// middle slice, so all the usual caveats pertaining to `transmute::<T, U>` also apply here.
1815 /// # #![feature(slice_align_to)]
1817 /// let mut bytes: [u8; 7] = [1, 2, 3, 4, 5, 6, 7];
1818 /// let (prefix, shorts, suffix) = bytes.align_to_mut::<u16>();
1819 /// // less_efficient_algorithm_for_bytes(prefix);
1820 /// // more_efficient_algorithm_for_aligned_shorts(shorts);
1821 /// // less_efficient_algorithm_for_bytes(suffix);
1824 #[unstable(feature = "slice_align_to", issue = "44488")]
1825 pub unsafe fn align_to_mut<U>(&mut self) -> (&mut [T], &mut [U], &mut [T]) {
1826 // Note that most of this function will be constant-evaluated,
1827 if ::mem::size_of::<U>() == 0 || ::mem::size_of::<T>() == 0 {
1828 // handle ZSTs specially, which is – don't handle them at all.
1829 return (self, &mut [], &mut []);
1832 // First, find at what point do we split between the first and 2nd slice. Easy with
1833 // ptr.align_offset.
1834 let ptr = self.as_ptr();
1835 let offset = ::ptr::align_offset(ptr, ::mem::align_of::<U>());
1836 if offset > self.len() {
1837 return (self, &mut [], &mut []);
1839 let (left, rest) = self.split_at_mut(offset);
1840 let (us_len, ts_len) = rest.align_to_offsets::<U>();
1841 let mut_ptr = rest.as_mut_ptr();
1843 from_raw_parts_mut(mut_ptr as *mut U, us_len),
1844 from_raw_parts_mut(mut_ptr.offset((rest.len() - ts_len) as isize), ts_len))
1849 #[lang = "slice_u8"]
1852 /// Checks if all bytes in this slice are within the ASCII range.
1853 #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
1855 pub fn is_ascii(&self) -> bool {
1856 self.iter().all(|b| b.is_ascii())
1859 /// Checks that two slices are an ASCII case-insensitive match.
1861 /// Same as `to_ascii_lowercase(a) == to_ascii_lowercase(b)`,
1862 /// but without allocating and copying temporaries.
1863 #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
1865 pub fn eq_ignore_ascii_case(&self, other: &[u8]) -> bool {
1866 self.len() == other.len() &&
1867 self.iter().zip(other).all(|(a, b)| {
1868 a.eq_ignore_ascii_case(b)
1872 /// Converts this slice to its ASCII upper case equivalent in-place.
1874 /// ASCII letters 'a' to 'z' are mapped to 'A' to 'Z',
1875 /// but non-ASCII letters are unchanged.
1877 /// To return a new uppercased value without modifying the existing one, use
1878 /// [`to_ascii_uppercase`].
1880 /// [`to_ascii_uppercase`]: #method.to_ascii_uppercase
1881 #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
1883 pub fn make_ascii_uppercase(&mut self) {
1885 byte.make_ascii_uppercase();
1889 /// Converts this slice to its ASCII lower case equivalent in-place.
1891 /// ASCII letters 'A' to 'Z' are mapped to 'a' to 'z',
1892 /// but non-ASCII letters are unchanged.
1894 /// To return a new lowercased value without modifying the existing one, use
1895 /// [`to_ascii_lowercase`].
1897 /// [`to_ascii_lowercase`]: #method.to_ascii_lowercase
1898 #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
1900 pub fn make_ascii_lowercase(&mut self) {
1902 byte.make_ascii_lowercase();
1908 #[stable(feature = "rust1", since = "1.0.0")]
1909 #[rustc_on_unimplemented = "slice indices are of type `usize` or ranges of `usize`"]
1910 impl<T, I> ops::Index<I> for [T]
1911 where I: SliceIndex<[T]>
1913 type Output = I::Output;
1916 fn index(&self, index: I) -> &I::Output {
1921 #[stable(feature = "rust1", since = "1.0.0")]
1922 #[rustc_on_unimplemented = "slice indices are of type `usize` or ranges of `usize`"]
1923 impl<T, I> ops::IndexMut<I> for [T]
1924 where I: SliceIndex<[T]>
1927 fn index_mut(&mut self, index: I) -> &mut I::Output {
1928 index.index_mut(self)
1934 fn slice_index_len_fail(index: usize, len: usize) -> ! {
1935 panic!("index {} out of range for slice of length {}", index, len);
1940 fn slice_index_order_fail(index: usize, end: usize) -> ! {
1941 panic!("slice index starts at {} but ends at {}", index, end);
1946 fn slice_index_overflow_fail() -> ! {
1947 panic!("attempted to index slice up to maximum usize");
1950 mod private_slice_index {
1952 #[stable(feature = "slice_get_slice", since = "1.28.0")]
1955 #[stable(feature = "slice_get_slice", since = "1.28.0")]
1956 impl Sealed for usize {}
1957 #[stable(feature = "slice_get_slice", since = "1.28.0")]
1958 impl Sealed for ops::Range<usize> {}
1959 #[stable(feature = "slice_get_slice", since = "1.28.0")]
1960 impl Sealed for ops::RangeTo<usize> {}
1961 #[stable(feature = "slice_get_slice", since = "1.28.0")]
1962 impl Sealed for ops::RangeFrom<usize> {}
1963 #[stable(feature = "slice_get_slice", since = "1.28.0")]
1964 impl Sealed for ops::RangeFull {}
1965 #[stable(feature = "slice_get_slice", since = "1.28.0")]
1966 impl Sealed for ops::RangeInclusive<usize> {}
1967 #[stable(feature = "slice_get_slice", since = "1.28.0")]
1968 impl Sealed for ops::RangeToInclusive<usize> {}
1971 /// A helper trait used for indexing operations.
1972 #[stable(feature = "slice_get_slice", since = "1.28.0")]
1973 #[rustc_on_unimplemented = "slice indices are of type `usize` or ranges of `usize`"]
1974 pub trait SliceIndex<T: ?Sized>: private_slice_index::Sealed {
1975 /// The output type returned by methods.
1976 #[stable(feature = "slice_get_slice", since = "1.28.0")]
1977 type Output: ?Sized;
1979 /// Returns a shared reference to the output at this location, if in
1981 #[unstable(feature = "slice_index_methods", issue = "0")]
1982 fn get(self, slice: &T) -> Option<&Self::Output>;
1984 /// Returns a mutable reference to the output at this location, if in
1986 #[unstable(feature = "slice_index_methods", issue = "0")]
1987 fn get_mut(self, slice: &mut T) -> Option<&mut Self::Output>;
1989 /// Returns a shared reference to the output at this location, without
1990 /// performing any bounds checking.
1991 #[unstable(feature = "slice_index_methods", issue = "0")]
1992 unsafe fn get_unchecked(self, slice: &T) -> &Self::Output;
1994 /// Returns a mutable reference to the output at this location, without
1995 /// performing any bounds checking.
1996 #[unstable(feature = "slice_index_methods", issue = "0")]
1997 unsafe fn get_unchecked_mut(self, slice: &mut T) -> &mut Self::Output;
1999 /// Returns a shared reference to the output at this location, panicking
2000 /// if out of bounds.
2001 #[unstable(feature = "slice_index_methods", issue = "0")]
2002 fn index(self, slice: &T) -> &Self::Output;
2004 /// Returns a mutable reference to the output at this location, panicking
2005 /// if out of bounds.
2006 #[unstable(feature = "slice_index_methods", issue = "0")]
2007 fn index_mut(self, slice: &mut T) -> &mut Self::Output;
2010 #[stable(feature = "slice-get-slice-impls", since = "1.15.0")]
2011 impl<T> SliceIndex<[T]> for usize {
2015 fn get(self, slice: &[T]) -> Option<&T> {
2016 if self < slice.len() {
2018 Some(self.get_unchecked(slice))
2026 fn get_mut(self, slice: &mut [T]) -> Option<&mut T> {
2027 if self < slice.len() {
2029 Some(self.get_unchecked_mut(slice))
2037 unsafe fn get_unchecked(self, slice: &[T]) -> &T {
2038 &*slice.as_ptr().offset(self as isize)
2042 unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut T {
2043 &mut *slice.as_mut_ptr().offset(self as isize)
2047 fn index(self, slice: &[T]) -> &T {
2048 // NB: use intrinsic indexing
2053 fn index_mut(self, slice: &mut [T]) -> &mut T {
2054 // NB: use intrinsic indexing
2059 #[stable(feature = "slice-get-slice-impls", since = "1.15.0")]
2060 impl<T> SliceIndex<[T]> for ops::Range<usize> {
2064 fn get(self, slice: &[T]) -> Option<&[T]> {
2065 if self.start > self.end || self.end > slice.len() {
2069 Some(self.get_unchecked(slice))
2075 fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
2076 if self.start > self.end || self.end > slice.len() {
2080 Some(self.get_unchecked_mut(slice))
2086 unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
2087 from_raw_parts(slice.as_ptr().offset(self.start as isize), self.end - self.start)
2091 unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
2092 from_raw_parts_mut(slice.as_mut_ptr().offset(self.start as isize), self.end - self.start)
2096 fn index(self, slice: &[T]) -> &[T] {
2097 if self.start > self.end {
2098 slice_index_order_fail(self.start, self.end);
2099 } else if self.end > slice.len() {
2100 slice_index_len_fail(self.end, slice.len());
2103 self.get_unchecked(slice)
2108 fn index_mut(self, slice: &mut [T]) -> &mut [T] {
2109 if self.start > self.end {
2110 slice_index_order_fail(self.start, self.end);
2111 } else if self.end > slice.len() {
2112 slice_index_len_fail(self.end, slice.len());
2115 self.get_unchecked_mut(slice)
2120 #[stable(feature = "slice-get-slice-impls", since = "1.15.0")]
2121 impl<T> SliceIndex<[T]> for ops::RangeTo<usize> {
2125 fn get(self, slice: &[T]) -> Option<&[T]> {
2126 (0..self.end).get(slice)
2130 fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
2131 (0..self.end).get_mut(slice)
2135 unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
2136 (0..self.end).get_unchecked(slice)
2140 unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
2141 (0..self.end).get_unchecked_mut(slice)
2145 fn index(self, slice: &[T]) -> &[T] {
2146 (0..self.end).index(slice)
2150 fn index_mut(self, slice: &mut [T]) -> &mut [T] {
2151 (0..self.end).index_mut(slice)
2155 #[stable(feature = "slice-get-slice-impls", since = "1.15.0")]
2156 impl<T> SliceIndex<[T]> for ops::RangeFrom<usize> {
2160 fn get(self, slice: &[T]) -> Option<&[T]> {
2161 (self.start..slice.len()).get(slice)
2165 fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
2166 (self.start..slice.len()).get_mut(slice)
2170 unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
2171 (self.start..slice.len()).get_unchecked(slice)
2175 unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
2176 (self.start..slice.len()).get_unchecked_mut(slice)
2180 fn index(self, slice: &[T]) -> &[T] {
2181 (self.start..slice.len()).index(slice)
2185 fn index_mut(self, slice: &mut [T]) -> &mut [T] {
2186 (self.start..slice.len()).index_mut(slice)
2190 #[stable(feature = "slice-get-slice-impls", since = "1.15.0")]
2191 impl<T> SliceIndex<[T]> for ops::RangeFull {
2195 fn get(self, slice: &[T]) -> Option<&[T]> {
2200 fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
2205 unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
2210 unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
2215 fn index(self, slice: &[T]) -> &[T] {
2220 fn index_mut(self, slice: &mut [T]) -> &mut [T] {
2226 #[stable(feature = "inclusive_range", since = "1.26.0")]
2227 impl<T> SliceIndex<[T]> for ops::RangeInclusive<usize> {
2231 fn get(self, slice: &[T]) -> Option<&[T]> {
2232 if *self.end() == usize::max_value() { None }
2233 else { (*self.start()..self.end() + 1).get(slice) }
2237 fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
2238 if *self.end() == usize::max_value() { None }
2239 else { (*self.start()..self.end() + 1).get_mut(slice) }
2243 unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
2244 (*self.start()..self.end() + 1).get_unchecked(slice)
2248 unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
2249 (*self.start()..self.end() + 1).get_unchecked_mut(slice)
2253 fn index(self, slice: &[T]) -> &[T] {
2254 if *self.end() == usize::max_value() { slice_index_overflow_fail(); }
2255 (*self.start()..self.end() + 1).index(slice)
2259 fn index_mut(self, slice: &mut [T]) -> &mut [T] {
2260 if *self.end() == usize::max_value() { slice_index_overflow_fail(); }
2261 (*self.start()..self.end() + 1).index_mut(slice)
2265 #[stable(feature = "inclusive_range", since = "1.26.0")]
2266 impl<T> SliceIndex<[T]> for ops::RangeToInclusive<usize> {
2270 fn get(self, slice: &[T]) -> Option<&[T]> {
2271 (0..=self.end).get(slice)
2275 fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
2276 (0..=self.end).get_mut(slice)
2280 unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
2281 (0..=self.end).get_unchecked(slice)
2285 unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
2286 (0..=self.end).get_unchecked_mut(slice)
2290 fn index(self, slice: &[T]) -> &[T] {
2291 (0..=self.end).index(slice)
2295 fn index_mut(self, slice: &mut [T]) -> &mut [T] {
2296 (0..=self.end).index_mut(slice)
2300 ////////////////////////////////////////////////////////////////////////////////
2302 ////////////////////////////////////////////////////////////////////////////////
2304 #[stable(feature = "rust1", since = "1.0.0")]
2305 impl<'a, T> Default for &'a [T] {
2306 /// Creates an empty slice.
2307 fn default() -> &'a [T] { &[] }
2310 #[stable(feature = "mut_slice_default", since = "1.5.0")]
2311 impl<'a, T> Default for &'a mut [T] {
2312 /// Creates a mutable empty slice.
2313 fn default() -> &'a mut [T] { &mut [] }
2320 #[stable(feature = "rust1", since = "1.0.0")]
2321 impl<'a, T> IntoIterator for &'a [T] {
2323 type IntoIter = Iter<'a, T>;
2325 fn into_iter(self) -> Iter<'a, T> {
2330 #[stable(feature = "rust1", since = "1.0.0")]
2331 impl<'a, T> IntoIterator for &'a mut [T] {
2332 type Item = &'a mut T;
2333 type IntoIter = IterMut<'a, T>;
2335 fn into_iter(self) -> IterMut<'a, T> {
2340 // Macro helper functions
2342 fn size_from_ptr<T>(_: *const T) -> usize {
2346 // Inlining is_empty and len makes a huge performance difference
2347 macro_rules! is_empty {
2348 // The way we encode the length of a ZST iterator, this works both for ZST
2350 ($self: ident) => {$self.ptr == $self.end}
2353 ($self: ident) => {{
2354 let start = $self.ptr;
2355 if size_from_ptr(start) == 0 {
2356 ($self.end as usize).wrapping_sub(start as usize)
2358 $self.end.offset_from(start) as usize
2362 // To get rid of some bounds checks (see `position`), for some reason it
2363 // makes a difference to compute the length in this way.
2364 // (Tested by `codegen/slice-position-bounds-check`.)
2366 ($self: ident) => {{
2367 let start = $self.ptr;
2368 let diff = ($self.end as usize).wrapping_sub(start as usize);
2369 let size = size_from_ptr(start);
2373 // Using division instead of `offset_from` helps LLVM remove bounds checks
2379 // The shared definition of the `Iter` and `IterMut` iterators
2380 macro_rules! iterator {
2381 (struct $name:ident -> $ptr:ty, $elem:ty, $raw_mut:tt, $( $mut_:tt )*) => {
2382 impl<'a, T> $name<'a, T> {
2383 // Helper function for creating a slice from the iterator.
2385 fn make_slice(&self) -> &'a [T] {
2386 unsafe { from_raw_parts(self.ptr, len2!(self)) }
2389 // Helper function for moving the start of the iterator forwards by `offset` elements,
2390 // returning the old start.
2391 // Unsafe because the offset must be in-bounds or one-past-the-end.
2393 unsafe fn post_inc_start(&mut self, offset: isize) -> * $raw_mut T {
2394 if mem::size_of::<T>() == 0 {
2395 // This is *reducing* the length. `ptr` never changes with ZST.
2396 self.end = (self.end as * $raw_mut u8).wrapping_offset(-offset) as * $raw_mut T;
2400 self.ptr = self.ptr.offset(offset);
2405 // Helper function for moving the end of the iterator backwards by `offset` elements,
2406 // returning the new end.
2407 // Unsafe because the offset must be in-bounds or one-past-the-end.
2409 unsafe fn pre_dec_end(&mut self, offset: isize) -> * $raw_mut T {
2410 if mem::size_of::<T>() == 0 {
2411 self.end = (self.end as * $raw_mut u8).wrapping_offset(-offset) as * $raw_mut T;
2414 self.end = self.end.offset(-offset);
2420 #[stable(feature = "rust1", since = "1.0.0")]
2421 impl<'a, T> ExactSizeIterator for $name<'a, T> {
2423 fn len(&self) -> usize {
2424 unsafe { len!(self) }
2428 fn is_empty(&self) -> bool {
2433 #[stable(feature = "rust1", since = "1.0.0")]
2434 impl<'a, T> Iterator for $name<'a, T> {
2438 fn next(&mut self) -> Option<$elem> {
2439 // could be implemented with slices, but this avoids bounds checks
2441 assume(!self.ptr.is_null());
2442 if mem::size_of::<T>() != 0 {
2443 assume(!self.end.is_null());
2445 if is_empty!(self) {
2448 Some(& $( $mut_ )* *self.post_inc_start(1))
2454 fn size_hint(&self) -> (usize, Option<usize>) {
2455 let exact = unsafe { len!(self) };
2456 (exact, Some(exact))
2460 fn count(self) -> usize {
2465 fn nth(&mut self, n: usize) -> Option<$elem> {
2466 if n >= unsafe { len!(self) } {
2467 // This iterator is now empty.
2468 if mem::size_of::<T>() == 0 {
2469 // We have to do it this way as `ptr` may never be 0, but `end`
2470 // could be (due to wrapping).
2471 self.end = self.ptr;
2473 self.ptr = self.end;
2477 // We are in bounds. `offset` does the right thing even for ZSTs.
2479 let elem = Some(& $( $mut_ )* *self.ptr.offset(n as isize));
2480 self.post_inc_start((n as isize).wrapping_add(1));
2486 fn last(mut self) -> Option<$elem> {
2491 fn try_fold<B, F, R>(&mut self, init: B, mut f: F) -> R where
2492 Self: Sized, F: FnMut(B, Self::Item) -> R, R: Try<Ok=B>
2494 // manual unrolling is needed when there are conditional exits from the loop
2495 let mut accum = init;
2497 while len!(self) >= 4 {
2498 accum = f(accum, & $( $mut_ )* *self.post_inc_start(1))?;
2499 accum = f(accum, & $( $mut_ )* *self.post_inc_start(1))?;
2500 accum = f(accum, & $( $mut_ )* *self.post_inc_start(1))?;
2501 accum = f(accum, & $( $mut_ )* *self.post_inc_start(1))?;
2503 while !is_empty!(self) {
2504 accum = f(accum, & $( $mut_ )* *self.post_inc_start(1))?;
2511 fn fold<Acc, Fold>(mut self, init: Acc, mut f: Fold) -> Acc
2512 where Fold: FnMut(Acc, Self::Item) -> Acc,
2514 // Let LLVM unroll this, rather than using the default
2515 // impl that would force the manual unrolling above
2516 let mut accum = init;
2517 while let Some(x) = self.next() {
2518 accum = f(accum, x);
2524 #[rustc_inherit_overflow_checks]
2525 fn position<P>(&mut self, mut predicate: P) -> Option<usize> where
2527 P: FnMut(Self::Item) -> bool,
2529 // The addition might panic on overflow.
2530 let n = len2!(self);
2531 self.try_fold(0, move |i, x| {
2532 if predicate(x) { Err(i) }
2536 unsafe { assume(i < n) };
2542 fn rposition<P>(&mut self, mut predicate: P) -> Option<usize> where
2543 P: FnMut(Self::Item) -> bool,
2544 Self: Sized + ExactSizeIterator + DoubleEndedIterator
2546 // No need for an overflow check here, because `ExactSizeIterator`
2547 let n = len2!(self);
2548 self.try_rfold(n, move |i, x| {
2550 if predicate(x) { Err(i) }
2554 unsafe { assume(i < n) };
2560 #[stable(feature = "rust1", since = "1.0.0")]
2561 impl<'a, T> DoubleEndedIterator for $name<'a, T> {
2563 fn next_back(&mut self) -> Option<$elem> {
2564 // could be implemented with slices, but this avoids bounds checks
2566 assume(!self.ptr.is_null());
2567 if mem::size_of::<T>() != 0 {
2568 assume(!self.end.is_null());
2570 if is_empty!(self) {
2573 Some(& $( $mut_ )* *self.pre_dec_end(1))
2579 fn try_rfold<B, F, R>(&mut self, init: B, mut f: F) -> R where
2580 Self: Sized, F: FnMut(B, Self::Item) -> R, R: Try<Ok=B>
2582 // manual unrolling is needed when there are conditional exits from the loop
2583 let mut accum = init;
2585 while len!(self) >= 4 {
2586 accum = f(accum, & $( $mut_ )* *self.pre_dec_end(1))?;
2587 accum = f(accum, & $( $mut_ )* *self.pre_dec_end(1))?;
2588 accum = f(accum, & $( $mut_ )* *self.pre_dec_end(1))?;
2589 accum = f(accum, & $( $mut_ )* *self.pre_dec_end(1))?;
2591 // inlining is_empty everywhere makes a huge performance difference
2592 while !is_empty!(self) {
2593 accum = f(accum, & $( $mut_ )* *self.pre_dec_end(1))?;
2600 fn rfold<Acc, Fold>(mut self, init: Acc, mut f: Fold) -> Acc
2601 where Fold: FnMut(Acc, Self::Item) -> Acc,
2603 // Let LLVM unroll this, rather than using the default
2604 // impl that would force the manual unrolling above
2605 let mut accum = init;
2606 while let Some(x) = self.next_back() {
2607 accum = f(accum, x);
2613 #[stable(feature = "fused", since = "1.26.0")]
2614 impl<'a, T> FusedIterator for $name<'a, T> {}
2616 #[unstable(feature = "trusted_len", issue = "37572")]
2617 unsafe impl<'a, T> TrustedLen for $name<'a, T> {}
2621 /// Immutable slice iterator
2623 /// This struct is created by the [`iter`] method on [slices].
2630 /// // First, we declare a type which has `iter` method to get the `Iter` struct (&[usize here]):
2631 /// let slice = &[1, 2, 3];
2633 /// // Then, we iterate over it:
2634 /// for element in slice.iter() {
2635 /// println!("{}", element);
2639 /// [`iter`]: ../../std/primitive.slice.html#method.iter
2640 /// [slices]: ../../std/primitive.slice.html
2641 #[stable(feature = "rust1", since = "1.0.0")]
2642 pub struct Iter<'a, T: 'a> {
2644 end: *const T, // If T is a ZST, this is actually ptr+len. This encoding is picked so that
2645 // ptr == end is a quick test for the Iterator being empty, that works
2646 // for both ZST and non-ZST.
2647 _marker: marker::PhantomData<&'a T>,
2650 #[stable(feature = "core_impl_debug", since = "1.9.0")]
2651 impl<'a, T: 'a + fmt::Debug> fmt::Debug for Iter<'a, T> {
2652 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
2653 f.debug_tuple("Iter")
2654 .field(&self.as_slice())
2659 #[stable(feature = "rust1", since = "1.0.0")]
2660 unsafe impl<'a, T: Sync> Sync for Iter<'a, T> {}
2661 #[stable(feature = "rust1", since = "1.0.0")]
2662 unsafe impl<'a, T: Sync> Send for Iter<'a, T> {}
2664 impl<'a, T> Iter<'a, T> {
2665 /// View the underlying data as a subslice of the original data.
2667 /// This has the same lifetime as the original slice, and so the
2668 /// iterator can continue to be used while this exists.
2675 /// // First, we declare a type which has the `iter` method to get the `Iter`
2676 /// // struct (&[usize here]):
2677 /// let slice = &[1, 2, 3];
2679 /// // Then, we get the iterator:
2680 /// let mut iter = slice.iter();
2681 /// // So if we print what `as_slice` method returns here, we have "[1, 2, 3]":
2682 /// println!("{:?}", iter.as_slice());
2684 /// // Next, we move to the second element of the slice:
2686 /// // Now `as_slice` returns "[2, 3]":
2687 /// println!("{:?}", iter.as_slice());
2689 #[stable(feature = "iter_to_slice", since = "1.4.0")]
2690 pub fn as_slice(&self) -> &'a [T] {
2695 iterator!{struct Iter -> *const T, &'a T, const, /* no mut */}
2697 #[stable(feature = "rust1", since = "1.0.0")]
2698 impl<'a, T> Clone for Iter<'a, T> {
2699 fn clone(&self) -> Iter<'a, T> { Iter { ptr: self.ptr, end: self.end, _marker: self._marker } }
2702 #[stable(feature = "slice_iter_as_ref", since = "1.13.0")]
2703 impl<'a, T> AsRef<[T]> for Iter<'a, T> {
2704 fn as_ref(&self) -> &[T] {
2709 /// Mutable slice iterator.
2711 /// This struct is created by the [`iter_mut`] method on [slices].
2718 /// // First, we declare a type which has `iter_mut` method to get the `IterMut`
2719 /// // struct (&[usize here]):
2720 /// let mut slice = &mut [1, 2, 3];
2722 /// // Then, we iterate over it and increment each element value:
2723 /// for element in slice.iter_mut() {
2727 /// // We now have "[2, 3, 4]":
2728 /// println!("{:?}", slice);
2731 /// [`iter_mut`]: ../../std/primitive.slice.html#method.iter_mut
2732 /// [slices]: ../../std/primitive.slice.html
2733 #[stable(feature = "rust1", since = "1.0.0")]
2734 pub struct IterMut<'a, T: 'a> {
2736 end: *mut T, // If T is a ZST, this is actually ptr+len. This encoding is picked so that
2737 // ptr == end is a quick test for the Iterator being empty, that works
2738 // for both ZST and non-ZST.
2739 _marker: marker::PhantomData<&'a mut T>,
2742 #[stable(feature = "core_impl_debug", since = "1.9.0")]
2743 impl<'a, T: 'a + fmt::Debug> fmt::Debug for IterMut<'a, T> {
2744 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
2745 f.debug_tuple("IterMut")
2746 .field(&self.make_slice())
2751 #[stable(feature = "rust1", since = "1.0.0")]
2752 unsafe impl<'a, T: Sync> Sync for IterMut<'a, T> {}
2753 #[stable(feature = "rust1", since = "1.0.0")]
2754 unsafe impl<'a, T: Send> Send for IterMut<'a, T> {}
2756 impl<'a, T> IterMut<'a, T> {
2757 /// View the underlying data as a subslice of the original data.
2759 /// To avoid creating `&mut` references that alias, this is forced
2760 /// to consume the iterator.
2767 /// // First, we declare a type which has `iter_mut` method to get the `IterMut`
2768 /// // struct (&[usize here]):
2769 /// let mut slice = &mut [1, 2, 3];
2772 /// // Then, we get the iterator:
2773 /// let mut iter = slice.iter_mut();
2774 /// // We move to next element:
2776 /// // So if we print what `into_slice` method returns here, we have "[2, 3]":
2777 /// println!("{:?}", iter.into_slice());
2780 /// // Now let's modify a value of the slice:
2782 /// // First we get back the iterator:
2783 /// let mut iter = slice.iter_mut();
2784 /// // We change the value of the first element of the slice returned by the `next` method:
2785 /// *iter.next().unwrap() += 1;
2787 /// // Now slice is "[2, 2, 3]":
2788 /// println!("{:?}", slice);
2790 #[stable(feature = "iter_to_slice", since = "1.4.0")]
2791 pub fn into_slice(self) -> &'a mut [T] {
2792 unsafe { from_raw_parts_mut(self.ptr, len2!(self)) }
2796 iterator!{struct IterMut -> *mut T, &'a mut T, mut, mut}
2798 /// An internal abstraction over the splitting iterators, so that
2799 /// splitn, splitn_mut etc can be implemented once.
2801 trait SplitIter: DoubleEndedIterator {
2802 /// Marks the underlying iterator as complete, extracting the remaining
2803 /// portion of the slice.
2804 fn finish(&mut self) -> Option<Self::Item>;
2807 /// An iterator over subslices separated by elements that match a predicate
2810 /// This struct is created by the [`split`] method on [slices].
2812 /// [`split`]: ../../std/primitive.slice.html#method.split
2813 /// [slices]: ../../std/primitive.slice.html
2814 #[stable(feature = "rust1", since = "1.0.0")]
2815 pub struct Split<'a, T:'a, P> where P: FnMut(&T) -> bool {
2821 #[stable(feature = "core_impl_debug", since = "1.9.0")]
2822 impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for Split<'a, T, P> where P: FnMut(&T) -> bool {
2823 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
2824 f.debug_struct("Split")
2825 .field("v", &self.v)
2826 .field("finished", &self.finished)
2831 // FIXME(#26925) Remove in favor of `#[derive(Clone)]`
2832 #[stable(feature = "rust1", since = "1.0.0")]
2833 impl<'a, T, P> Clone for Split<'a, T, P> where P: Clone + FnMut(&T) -> bool {
2834 fn clone(&self) -> Split<'a, T, P> {
2837 pred: self.pred.clone(),
2838 finished: self.finished,
2843 #[stable(feature = "rust1", since = "1.0.0")]
2844 impl<'a, T, P> Iterator for Split<'a, T, P> where P: FnMut(&T) -> bool {
2845 type Item = &'a [T];
2848 fn next(&mut self) -> Option<&'a [T]> {
2849 if self.finished { return None; }
2851 match self.v.iter().position(|x| (self.pred)(x)) {
2852 None => self.finish(),
2854 let ret = Some(&self.v[..idx]);
2855 self.v = &self.v[idx + 1..];
2862 fn size_hint(&self) -> (usize, Option<usize>) {
2866 (1, Some(self.v.len() + 1))
2871 #[stable(feature = "rust1", since = "1.0.0")]
2872 impl<'a, T, P> DoubleEndedIterator for Split<'a, T, P> where P: FnMut(&T) -> bool {
2874 fn next_back(&mut self) -> Option<&'a [T]> {
2875 if self.finished { return None; }
2877 match self.v.iter().rposition(|x| (self.pred)(x)) {
2878 None => self.finish(),
2880 let ret = Some(&self.v[idx + 1..]);
2881 self.v = &self.v[..idx];
2888 impl<'a, T, P> SplitIter for Split<'a, T, P> where P: FnMut(&T) -> bool {
2890 fn finish(&mut self) -> Option<&'a [T]> {
2891 if self.finished { None } else { self.finished = true; Some(self.v) }
2895 #[stable(feature = "fused", since = "1.26.0")]
2896 impl<'a, T, P> FusedIterator for Split<'a, T, P> where P: FnMut(&T) -> bool {}
2898 /// An iterator over the subslices of the vector which are separated
2899 /// by elements that match `pred`.
2901 /// This struct is created by the [`split_mut`] method on [slices].
2903 /// [`split_mut`]: ../../std/primitive.slice.html#method.split_mut
2904 /// [slices]: ../../std/primitive.slice.html
2905 #[stable(feature = "rust1", since = "1.0.0")]
2906 pub struct SplitMut<'a, T:'a, P> where P: FnMut(&T) -> bool {
2912 #[stable(feature = "core_impl_debug", since = "1.9.0")]
2913 impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {
2914 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
2915 f.debug_struct("SplitMut")
2916 .field("v", &self.v)
2917 .field("finished", &self.finished)
2922 impl<'a, T, P> SplitIter for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {
2924 fn finish(&mut self) -> Option<&'a mut [T]> {
2928 self.finished = true;
2929 Some(mem::replace(&mut self.v, &mut []))
2934 #[stable(feature = "rust1", since = "1.0.0")]
2935 impl<'a, T, P> Iterator for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {
2936 type Item = &'a mut [T];
2939 fn next(&mut self) -> Option<&'a mut [T]> {
2940 if self.finished { return None; }
2942 let idx_opt = { // work around borrowck limitations
2943 let pred = &mut self.pred;
2944 self.v.iter().position(|x| (*pred)(x))
2947 None => self.finish(),
2949 let tmp = mem::replace(&mut self.v, &mut []);
2950 let (head, tail) = tmp.split_at_mut(idx);
2951 self.v = &mut tail[1..];
2958 fn size_hint(&self) -> (usize, Option<usize>) {
2962 // if the predicate doesn't match anything, we yield one slice
2963 // if it matches every element, we yield len+1 empty slices.
2964 (1, Some(self.v.len() + 1))
2969 #[stable(feature = "rust1", since = "1.0.0")]
2970 impl<'a, T, P> DoubleEndedIterator for SplitMut<'a, T, P> where
2971 P: FnMut(&T) -> bool,
2974 fn next_back(&mut self) -> Option<&'a mut [T]> {
2975 if self.finished { return None; }
2977 let idx_opt = { // work around borrowck limitations
2978 let pred = &mut self.pred;
2979 self.v.iter().rposition(|x| (*pred)(x))
2982 None => self.finish(),
2984 let tmp = mem::replace(&mut self.v, &mut []);
2985 let (head, tail) = tmp.split_at_mut(idx);
2987 Some(&mut tail[1..])
2993 #[stable(feature = "fused", since = "1.26.0")]
2994 impl<'a, T, P> FusedIterator for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {}
2996 /// An iterator over subslices separated by elements that match a predicate
2997 /// function, starting from the end of the slice.
2999 /// This struct is created by the [`rsplit`] method on [slices].
3001 /// [`rsplit`]: ../../std/primitive.slice.html#method.rsplit
3002 /// [slices]: ../../std/primitive.slice.html
3003 #[stable(feature = "slice_rsplit", since = "1.27.0")]
3004 #[derive(Clone)] // Is this correct, or does it incorrectly require `T: Clone`?
3005 pub struct RSplit<'a, T:'a, P> where P: FnMut(&T) -> bool {
3006 inner: Split<'a, T, P>
3009 #[stable(feature = "slice_rsplit", since = "1.27.0")]
3010 impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for RSplit<'a, T, P> where P: FnMut(&T) -> bool {
3011 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
3012 f.debug_struct("RSplit")
3013 .field("v", &self.inner.v)
3014 .field("finished", &self.inner.finished)
3019 #[stable(feature = "slice_rsplit", since = "1.27.0")]
3020 impl<'a, T, P> Iterator for RSplit<'a, T, P> where P: FnMut(&T) -> bool {
3021 type Item = &'a [T];
3024 fn next(&mut self) -> Option<&'a [T]> {
3025 self.inner.next_back()
3029 fn size_hint(&self) -> (usize, Option<usize>) {
3030 self.inner.size_hint()
3034 #[stable(feature = "slice_rsplit", since = "1.27.0")]
3035 impl<'a, T, P> DoubleEndedIterator for RSplit<'a, T, P> where P: FnMut(&T) -> bool {
3037 fn next_back(&mut self) -> Option<&'a [T]> {
3042 #[stable(feature = "slice_rsplit", since = "1.27.0")]
3043 impl<'a, T, P> SplitIter for RSplit<'a, T, P> where P: FnMut(&T) -> bool {
3045 fn finish(&mut self) -> Option<&'a [T]> {
3050 #[stable(feature = "slice_rsplit", since = "1.27.0")]
3051 impl<'a, T, P> FusedIterator for RSplit<'a, T, P> where P: FnMut(&T) -> bool {}
3053 /// An iterator over the subslices of the vector which are separated
3054 /// by elements that match `pred`, starting from the end of the slice.
3056 /// This struct is created by the [`rsplit_mut`] method on [slices].
3058 /// [`rsplit_mut`]: ../../std/primitive.slice.html#method.rsplit_mut
3059 /// [slices]: ../../std/primitive.slice.html
3060 #[stable(feature = "slice_rsplit", since = "1.27.0")]
3061 pub struct RSplitMut<'a, T:'a, P> where P: FnMut(&T) -> bool {
3062 inner: SplitMut<'a, T, P>
3065 #[stable(feature = "slice_rsplit", since = "1.27.0")]
3066 impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for RSplitMut<'a, T, P> where P: FnMut(&T) -> bool {
3067 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
3068 f.debug_struct("RSplitMut")
3069 .field("v", &self.inner.v)
3070 .field("finished", &self.inner.finished)
3075 #[stable(feature = "slice_rsplit", since = "1.27.0")]
3076 impl<'a, T, P> SplitIter for RSplitMut<'a, T, P> where P: FnMut(&T) -> bool {
3078 fn finish(&mut self) -> Option<&'a mut [T]> {
3083 #[stable(feature = "slice_rsplit", since = "1.27.0")]
3084 impl<'a, T, P> Iterator for RSplitMut<'a, T, P> where P: FnMut(&T) -> bool {
3085 type Item = &'a mut [T];
3088 fn next(&mut self) -> Option<&'a mut [T]> {
3089 self.inner.next_back()
3093 fn size_hint(&self) -> (usize, Option<usize>) {
3094 self.inner.size_hint()
3098 #[stable(feature = "slice_rsplit", since = "1.27.0")]
3099 impl<'a, T, P> DoubleEndedIterator for RSplitMut<'a, T, P> where
3100 P: FnMut(&T) -> bool,
3103 fn next_back(&mut self) -> Option<&'a mut [T]> {
3108 #[stable(feature = "slice_rsplit", since = "1.27.0")]
3109 impl<'a, T, P> FusedIterator for RSplitMut<'a, T, P> where P: FnMut(&T) -> bool {}
3111 /// An private iterator over subslices separated by elements that
3112 /// match a predicate function, splitting at most a fixed number of
3115 struct GenericSplitN<I> {
3120 impl<T, I: SplitIter<Item=T>> Iterator for GenericSplitN<I> {
3124 fn next(&mut self) -> Option<T> {
3127 1 => { self.count -= 1; self.iter.finish() }
3128 _ => { self.count -= 1; self.iter.next() }
3133 fn size_hint(&self) -> (usize, Option<usize>) {
3134 let (lower, upper_opt) = self.iter.size_hint();
3135 (lower, upper_opt.map(|upper| cmp::min(self.count, upper)))
3139 /// An iterator over subslices separated by elements that match a predicate
3140 /// function, limited to a given number of splits.
3142 /// This struct is created by the [`splitn`] method on [slices].
3144 /// [`splitn`]: ../../std/primitive.slice.html#method.splitn
3145 /// [slices]: ../../std/primitive.slice.html
3146 #[stable(feature = "rust1", since = "1.0.0")]
3147 pub struct SplitN<'a, T: 'a, P> where P: FnMut(&T) -> bool {
3148 inner: GenericSplitN<Split<'a, T, P>>
3151 #[stable(feature = "core_impl_debug", since = "1.9.0")]
3152 impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for SplitN<'a, T, P> where P: FnMut(&T) -> bool {
3153 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
3154 f.debug_struct("SplitN")
3155 .field("inner", &self.inner)
3160 /// An iterator over subslices separated by elements that match a
3161 /// predicate function, limited to a given number of splits, starting
3162 /// from the end of the slice.
3164 /// This struct is created by the [`rsplitn`] method on [slices].
3166 /// [`rsplitn`]: ../../std/primitive.slice.html#method.rsplitn
3167 /// [slices]: ../../std/primitive.slice.html
3168 #[stable(feature = "rust1", since = "1.0.0")]
3169 pub struct RSplitN<'a, T: 'a, P> where P: FnMut(&T) -> bool {
3170 inner: GenericSplitN<RSplit<'a, T, P>>
3173 #[stable(feature = "core_impl_debug", since = "1.9.0")]
3174 impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for RSplitN<'a, T, P> where P: FnMut(&T) -> bool {
3175 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
3176 f.debug_struct("RSplitN")
3177 .field("inner", &self.inner)
3182 /// An iterator over subslices separated by elements that match a predicate
3183 /// function, limited to a given number of splits.
3185 /// This struct is created by the [`splitn_mut`] method on [slices].
3187 /// [`splitn_mut`]: ../../std/primitive.slice.html#method.splitn_mut
3188 /// [slices]: ../../std/primitive.slice.html
3189 #[stable(feature = "rust1", since = "1.0.0")]
3190 pub struct SplitNMut<'a, T: 'a, P> where P: FnMut(&T) -> bool {
3191 inner: GenericSplitN<SplitMut<'a, T, P>>
3194 #[stable(feature = "core_impl_debug", since = "1.9.0")]
3195 impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for SplitNMut<'a, T, P> where P: FnMut(&T) -> bool {
3196 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
3197 f.debug_struct("SplitNMut")
3198 .field("inner", &self.inner)
3203 /// An iterator over subslices separated by elements that match a
3204 /// predicate function, limited to a given number of splits, starting
3205 /// from the end of the slice.
3207 /// This struct is created by the [`rsplitn_mut`] method on [slices].
3209 /// [`rsplitn_mut`]: ../../std/primitive.slice.html#method.rsplitn_mut
3210 /// [slices]: ../../std/primitive.slice.html
3211 #[stable(feature = "rust1", since = "1.0.0")]
3212 pub struct RSplitNMut<'a, T: 'a, P> where P: FnMut(&T) -> bool {
3213 inner: GenericSplitN<RSplitMut<'a, T, P>>
3216 #[stable(feature = "core_impl_debug", since = "1.9.0")]
3217 impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for RSplitNMut<'a, T, P> where P: FnMut(&T) -> bool {
3218 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
3219 f.debug_struct("RSplitNMut")
3220 .field("inner", &self.inner)
3225 macro_rules! forward_iterator {
3226 ($name:ident: $elem:ident, $iter_of:ty) => {
3227 #[stable(feature = "rust1", since = "1.0.0")]
3228 impl<'a, $elem, P> Iterator for $name<'a, $elem, P> where
3229 P: FnMut(&T) -> bool
3231 type Item = $iter_of;
3234 fn next(&mut self) -> Option<$iter_of> {
3239 fn size_hint(&self) -> (usize, Option<usize>) {
3240 self.inner.size_hint()
3244 #[stable(feature = "fused", since = "1.26.0")]
3245 impl<'a, $elem, P> FusedIterator for $name<'a, $elem, P>
3246 where P: FnMut(&T) -> bool {}
3250 forward_iterator! { SplitN: T, &'a [T] }
3251 forward_iterator! { RSplitN: T, &'a [T] }
3252 forward_iterator! { SplitNMut: T, &'a mut [T] }
3253 forward_iterator! { RSplitNMut: T, &'a mut [T] }
3255 /// An iterator over overlapping subslices of length `size`.
3257 /// This struct is created by the [`windows`] method on [slices].
3259 /// [`windows`]: ../../std/primitive.slice.html#method.windows
3260 /// [slices]: ../../std/primitive.slice.html
3262 #[stable(feature = "rust1", since = "1.0.0")]
3263 pub struct Windows<'a, T:'a> {
3268 // FIXME(#26925) Remove in favor of `#[derive(Clone)]`
3269 #[stable(feature = "rust1", since = "1.0.0")]
3270 impl<'a, T> Clone for Windows<'a, T> {
3271 fn clone(&self) -> Windows<'a, T> {
3279 #[stable(feature = "rust1", since = "1.0.0")]
3280 impl<'a, T> Iterator for Windows<'a, T> {
3281 type Item = &'a [T];
3284 fn next(&mut self) -> Option<&'a [T]> {
3285 if self.size > self.v.len() {
3288 let ret = Some(&self.v[..self.size]);
3289 self.v = &self.v[1..];
3295 fn size_hint(&self) -> (usize, Option<usize>) {
3296 if self.size > self.v.len() {
3299 let size = self.v.len() - self.size + 1;
3305 fn count(self) -> usize {
3310 fn nth(&mut self, n: usize) -> Option<Self::Item> {
3311 let (end, overflow) = self.size.overflowing_add(n);
3312 if end > self.v.len() || overflow {
3316 let nth = &self.v[n..end];
3317 self.v = &self.v[n+1..];
3323 fn last(self) -> Option<Self::Item> {
3324 if self.size > self.v.len() {
3327 let start = self.v.len() - self.size;
3328 Some(&self.v[start..])
3333 #[stable(feature = "rust1", since = "1.0.0")]
3334 impl<'a, T> DoubleEndedIterator for Windows<'a, T> {
3336 fn next_back(&mut self) -> Option<&'a [T]> {
3337 if self.size > self.v.len() {
3340 let ret = Some(&self.v[self.v.len()-self.size..]);
3341 self.v = &self.v[..self.v.len()-1];
3347 #[stable(feature = "rust1", since = "1.0.0")]
3348 impl<'a, T> ExactSizeIterator for Windows<'a, T> {}
3350 #[unstable(feature = "trusted_len", issue = "37572")]
3351 unsafe impl<'a, T> TrustedLen for Windows<'a, T> {}
3353 #[stable(feature = "fused", since = "1.26.0")]
3354 impl<'a, T> FusedIterator for Windows<'a, T> {}
3357 unsafe impl<'a, T> TrustedRandomAccess for Windows<'a, T> {
3358 unsafe fn get_unchecked(&mut self, i: usize) -> &'a [T] {
3359 from_raw_parts(self.v.as_ptr().offset(i as isize), self.size)
3361 fn may_have_side_effect() -> bool { false }
3364 /// An iterator over a slice in (non-overlapping) chunks (`chunk_size` elements at a
3367 /// When the slice len is not evenly divided by the chunk size, the last slice
3368 /// of the iteration will be the remainder.
3370 /// This struct is created by the [`chunks`] method on [slices].
3372 /// [`chunks`]: ../../std/primitive.slice.html#method.chunks
3373 /// [slices]: ../../std/primitive.slice.html
3375 #[stable(feature = "rust1", since = "1.0.0")]
3376 pub struct Chunks<'a, T:'a> {
3381 // FIXME(#26925) Remove in favor of `#[derive(Clone)]`
3382 #[stable(feature = "rust1", since = "1.0.0")]
3383 impl<'a, T> Clone for Chunks<'a, T> {
3384 fn clone(&self) -> Chunks<'a, T> {
3387 chunk_size: self.chunk_size,
3392 #[stable(feature = "rust1", since = "1.0.0")]
3393 impl<'a, T> Iterator for Chunks<'a, T> {
3394 type Item = &'a [T];
3397 fn next(&mut self) -> Option<&'a [T]> {
3398 if self.v.is_empty() {
3401 let chunksz = cmp::min(self.v.len(), self.chunk_size);
3402 let (fst, snd) = self.v.split_at(chunksz);
3409 fn size_hint(&self) -> (usize, Option<usize>) {
3410 if self.v.is_empty() {
3413 let n = self.v.len() / self.chunk_size;
3414 let rem = self.v.len() % self.chunk_size;
3415 let n = if rem > 0 { n+1 } else { n };
3421 fn count(self) -> usize {
3426 fn nth(&mut self, n: usize) -> Option<Self::Item> {
3427 let (start, overflow) = n.overflowing_mul(self.chunk_size);
3428 if start >= self.v.len() || overflow {
3432 let end = match start.checked_add(self.chunk_size) {
3433 Some(sum) => cmp::min(self.v.len(), sum),
3434 None => self.v.len(),
3436 let nth = &self.v[start..end];
3437 self.v = &self.v[end..];
3443 fn last(self) -> Option<Self::Item> {
3444 if self.v.is_empty() {
3447 let start = (self.v.len() - 1) / self.chunk_size * self.chunk_size;
3448 Some(&self.v[start..])
3453 #[stable(feature = "rust1", since = "1.0.0")]
3454 impl<'a, T> DoubleEndedIterator for Chunks<'a, T> {
3456 fn next_back(&mut self) -> Option<&'a [T]> {
3457 if self.v.is_empty() {
3460 let remainder = self.v.len() % self.chunk_size;
3461 let chunksz = if remainder != 0 { remainder } else { self.chunk_size };
3462 let (fst, snd) = self.v.split_at(self.v.len() - chunksz);
3469 #[stable(feature = "rust1", since = "1.0.0")]
3470 impl<'a, T> ExactSizeIterator for Chunks<'a, T> {}
3472 #[unstable(feature = "trusted_len", issue = "37572")]
3473 unsafe impl<'a, T> TrustedLen for Chunks<'a, T> {}
3475 #[stable(feature = "fused", since = "1.26.0")]
3476 impl<'a, T> FusedIterator for Chunks<'a, T> {}
3479 unsafe impl<'a, T> TrustedRandomAccess for Chunks<'a, T> {
3480 unsafe fn get_unchecked(&mut self, i: usize) -> &'a [T] {
3481 let start = i * self.chunk_size;
3482 let end = match start.checked_add(self.chunk_size) {
3483 None => self.v.len(),
3484 Some(end) => cmp::min(end, self.v.len()),
3486 from_raw_parts(self.v.as_ptr().offset(start as isize), end - start)
3488 fn may_have_side_effect() -> bool { false }
3491 /// An iterator over a slice in (non-overlapping) mutable chunks (`chunk_size`
3492 /// elements at a time). When the slice len is not evenly divided by the chunk
3493 /// size, the last slice of the iteration will be the remainder.
3495 /// This struct is created by the [`chunks_mut`] method on [slices].
3497 /// [`chunks_mut`]: ../../std/primitive.slice.html#method.chunks_mut
3498 /// [slices]: ../../std/primitive.slice.html
3500 #[stable(feature = "rust1", since = "1.0.0")]
3501 pub struct ChunksMut<'a, T:'a> {
3506 #[stable(feature = "rust1", since = "1.0.0")]
3507 impl<'a, T> Iterator for ChunksMut<'a, T> {
3508 type Item = &'a mut [T];
3511 fn next(&mut self) -> Option<&'a mut [T]> {
3512 if self.v.is_empty() {
3515 let sz = cmp::min(self.v.len(), self.chunk_size);
3516 let tmp = mem::replace(&mut self.v, &mut []);
3517 let (head, tail) = tmp.split_at_mut(sz);
3524 fn size_hint(&self) -> (usize, Option<usize>) {
3525 if self.v.is_empty() {
3528 let n = self.v.len() / self.chunk_size;
3529 let rem = self.v.len() % self.chunk_size;
3530 let n = if rem > 0 { n + 1 } else { n };
3536 fn count(self) -> usize {
3541 fn nth(&mut self, n: usize) -> Option<&'a mut [T]> {
3542 let (start, overflow) = n.overflowing_mul(self.chunk_size);
3543 if start >= self.v.len() || overflow {
3547 let end = match start.checked_add(self.chunk_size) {
3548 Some(sum) => cmp::min(self.v.len(), sum),
3549 None => self.v.len(),
3551 let tmp = mem::replace(&mut self.v, &mut []);
3552 let (head, tail) = tmp.split_at_mut(end);
3553 let (_, nth) = head.split_at_mut(start);
3560 fn last(self) -> Option<Self::Item> {
3561 if self.v.is_empty() {
3564 let start = (self.v.len() - 1) / self.chunk_size * self.chunk_size;
3565 Some(&mut self.v[start..])
3570 #[stable(feature = "rust1", since = "1.0.0")]
3571 impl<'a, T> DoubleEndedIterator for ChunksMut<'a, T> {
3573 fn next_back(&mut self) -> Option<&'a mut [T]> {
3574 if self.v.is_empty() {
3577 let remainder = self.v.len() % self.chunk_size;
3578 let sz = if remainder != 0 { remainder } else { self.chunk_size };
3579 let tmp = mem::replace(&mut self.v, &mut []);
3580 let tmp_len = tmp.len();
3581 let (head, tail) = tmp.split_at_mut(tmp_len - sz);
3588 #[stable(feature = "rust1", since = "1.0.0")]
3589 impl<'a, T> ExactSizeIterator for ChunksMut<'a, T> {}
3591 #[unstable(feature = "trusted_len", issue = "37572")]
3592 unsafe impl<'a, T> TrustedLen for ChunksMut<'a, T> {}
3594 #[stable(feature = "fused", since = "1.26.0")]
3595 impl<'a, T> FusedIterator for ChunksMut<'a, T> {}
3598 unsafe impl<'a, T> TrustedRandomAccess for ChunksMut<'a, T> {
3599 unsafe fn get_unchecked(&mut self, i: usize) -> &'a mut [T] {
3600 let start = i * self.chunk_size;
3601 let end = match start.checked_add(self.chunk_size) {
3602 None => self.v.len(),
3603 Some(end) => cmp::min(end, self.v.len()),
3605 from_raw_parts_mut(self.v.as_mut_ptr().offset(start as isize), end - start)
3607 fn may_have_side_effect() -> bool { false }
3610 /// An iterator over a slice in (non-overlapping) chunks (`chunk_size` elements at a
3613 /// When the slice len is not evenly divided by the chunk size, the last
3614 /// up to `chunk_size-1` elements will be omitted but can be retrieved from
3615 /// the [`remainder`] function from the iterator.
3617 /// This struct is created by the [`exact_chunks`] method on [slices].
3619 /// [`exact_chunks`]: ../../std/primitive.slice.html#method.exact_chunks
3620 /// [`remainder`]: ../../std/slice/struct.ExactChunks.html#method.remainder
3621 /// [slices]: ../../std/primitive.slice.html
3623 #[unstable(feature = "exact_chunks", issue = "47115")]
3624 pub struct ExactChunks<'a, T:'a> {
3630 #[unstable(feature = "exact_chunks", issue = "47115")]
3631 impl<'a, T> ExactChunks<'a, T> {
3632 /// Return the remainder of the original slice that is not going to be
3633 /// returned by the iterator. The returned slice has at most `chunk_size-1`
3635 pub fn remainder(&self) -> &'a [T] {
3640 // FIXME(#26925) Remove in favor of `#[derive(Clone)]`
3641 #[unstable(feature = "exact_chunks", issue = "47115")]
3642 impl<'a, T> Clone for ExactChunks<'a, T> {
3643 fn clone(&self) -> ExactChunks<'a, T> {
3647 chunk_size: self.chunk_size,
3652 #[unstable(feature = "exact_chunks", issue = "47115")]
3653 impl<'a, T> Iterator for ExactChunks<'a, T> {
3654 type Item = &'a [T];
3657 fn next(&mut self) -> Option<&'a [T]> {
3658 if self.v.len() < self.chunk_size {
3661 let (fst, snd) = self.v.split_at(self.chunk_size);
3668 fn size_hint(&self) -> (usize, Option<usize>) {
3669 let n = self.v.len() / self.chunk_size;
3674 fn count(self) -> usize {
3679 fn nth(&mut self, n: usize) -> Option<Self::Item> {
3680 let (start, overflow) = n.overflowing_mul(self.chunk_size);
3681 if start >= self.v.len() || overflow {
3685 let (_, snd) = self.v.split_at(start);
3692 fn last(mut self) -> Option<Self::Item> {
3697 #[unstable(feature = "exact_chunks", issue = "47115")]
3698 impl<'a, T> DoubleEndedIterator for ExactChunks<'a, T> {
3700 fn next_back(&mut self) -> Option<&'a [T]> {
3701 if self.v.len() < self.chunk_size {
3704 let (fst, snd) = self.v.split_at(self.v.len() - self.chunk_size);
3711 #[unstable(feature = "exact_chunks", issue = "47115")]
3712 impl<'a, T> ExactSizeIterator for ExactChunks<'a, T> {
3713 fn is_empty(&self) -> bool {
3718 #[unstable(feature = "trusted_len", issue = "37572")]
3719 unsafe impl<'a, T> TrustedLen for ExactChunks<'a, T> {}
3721 #[unstable(feature = "exact_chunks", issue = "47115")]
3722 impl<'a, T> FusedIterator for ExactChunks<'a, T> {}
3725 unsafe impl<'a, T> TrustedRandomAccess for ExactChunks<'a, T> {
3726 unsafe fn get_unchecked(&mut self, i: usize) -> &'a [T] {
3727 let start = i * self.chunk_size;
3728 from_raw_parts(self.v.as_ptr().offset(start as isize), self.chunk_size)
3730 fn may_have_side_effect() -> bool { false }
3733 /// An iterator over a slice in (non-overlapping) mutable chunks (`chunk_size`
3734 /// elements at a time).
3736 /// When the slice len is not evenly divided by the chunk size, the last up to
3737 /// `chunk_size-1` elements will be omitted but can be retrieved from the
3738 /// [`into_remainder`] function from the iterator.
3740 /// This struct is created by the [`exact_chunks_mut`] method on [slices].
3742 /// [`exact_chunks_mut`]: ../../std/primitive.slice.html#method.exact_chunks_mut
3743 /// [`into_remainder`]: ../../std/slice/struct.ExactChunksMut.html#method.into_remainder
3744 /// [slices]: ../../std/primitive.slice.html
3746 #[unstable(feature = "exact_chunks", issue = "47115")]
3747 pub struct ExactChunksMut<'a, T:'a> {
3753 #[unstable(feature = "exact_chunks", issue = "47115")]
3754 impl<'a, T> ExactChunksMut<'a, T> {
3755 /// Return the remainder of the original slice that is not going to be
3756 /// returned by the iterator. The returned slice has at most `chunk_size-1`
3758 pub fn into_remainder(self) -> &'a mut [T] {
3763 #[unstable(feature = "exact_chunks", issue = "47115")]
3764 impl<'a, T> Iterator for ExactChunksMut<'a, T> {
3765 type Item = &'a mut [T];
3768 fn next(&mut self) -> Option<&'a mut [T]> {
3769 if self.v.len() < self.chunk_size {
3772 let tmp = mem::replace(&mut self.v, &mut []);
3773 let (head, tail) = tmp.split_at_mut(self.chunk_size);
3780 fn size_hint(&self) -> (usize, Option<usize>) {
3781 let n = self.v.len() / self.chunk_size;
3786 fn count(self) -> usize {
3791 fn nth(&mut self, n: usize) -> Option<&'a mut [T]> {
3792 let (start, overflow) = n.overflowing_mul(self.chunk_size);
3793 if start >= self.v.len() || overflow {
3797 let tmp = mem::replace(&mut self.v, &mut []);
3798 let (_, snd) = tmp.split_at_mut(start);
3805 fn last(mut self) -> Option<Self::Item> {
3810 #[unstable(feature = "exact_chunks", issue = "47115")]
3811 impl<'a, T> DoubleEndedIterator for ExactChunksMut<'a, T> {
3813 fn next_back(&mut self) -> Option<&'a mut [T]> {
3814 if self.v.len() < self.chunk_size {
3817 let tmp = mem::replace(&mut self.v, &mut []);
3818 let tmp_len = tmp.len();
3819 let (head, tail) = tmp.split_at_mut(tmp_len - self.chunk_size);
3826 #[unstable(feature = "exact_chunks", issue = "47115")]
3827 impl<'a, T> ExactSizeIterator for ExactChunksMut<'a, T> {
3828 fn is_empty(&self) -> bool {
3833 #[unstable(feature = "trusted_len", issue = "37572")]
3834 unsafe impl<'a, T> TrustedLen for ExactChunksMut<'a, T> {}
3836 #[unstable(feature = "exact_chunks", issue = "47115")]
3837 impl<'a, T> FusedIterator for ExactChunksMut<'a, T> {}
3840 unsafe impl<'a, T> TrustedRandomAccess for ExactChunksMut<'a, T> {
3841 unsafe fn get_unchecked(&mut self, i: usize) -> &'a mut [T] {
3842 let start = i * self.chunk_size;
3843 from_raw_parts_mut(self.v.as_mut_ptr().offset(start as isize), self.chunk_size)
3845 fn may_have_side_effect() -> bool { false }
3852 /// Forms a slice from a pointer and a length.
3854 /// The `len` argument is the number of **elements**, not the number of bytes.
3858 /// This function is unsafe as there is no guarantee that the given pointer is
3859 /// valid for `len` elements, nor whether the lifetime inferred is a suitable
3860 /// lifetime for the returned slice.
3862 /// `data` must be non-null and aligned, even for zero-length slices. One
3863 /// reason for this is that enum layout optimizations may rely on references
3864 /// (including slices of any length) being aligned and non-null to distinguish
3865 /// them from other data. You can obtain a pointer that is usable as `data`
3866 /// for zero-length slices using [`NonNull::dangling()`].
3870 /// The lifetime for the returned slice is inferred from its usage. To
3871 /// prevent accidental misuse, it's suggested to tie the lifetime to whichever
3872 /// source lifetime is safe in the context, such as by providing a helper
3873 /// function taking the lifetime of a host value for the slice, or by explicit
3881 /// // manifest a slice for a single element
3883 /// let ptr = &x as *const _;
3884 /// let slice = unsafe { slice::from_raw_parts(ptr, 1) };
3885 /// assert_eq!(slice[0], 42);
3888 /// [`NonNull::dangling()`]: ../../std/ptr/struct.NonNull.html#method.dangling
3890 #[stable(feature = "rust1", since = "1.0.0")]
3891 pub unsafe fn from_raw_parts<'a, T>(data: *const T, len: usize) -> &'a [T] {
3892 Repr { raw: FatPtr { data, len } }.rust
3895 /// Performs the same functionality as `from_raw_parts`, except that a mutable
3896 /// slice is returned.
3898 /// This function is unsafe for the same reasons as `from_raw_parts`, as well
3899 /// as not being able to provide a non-aliasing guarantee of the returned
3900 /// mutable slice. `data` must be non-null and aligned even for zero-length
3901 /// slices as with `from_raw_parts`.
3903 #[stable(feature = "rust1", since = "1.0.0")]
3904 pub unsafe fn from_raw_parts_mut<'a, T>(data: *mut T, len: usize) -> &'a mut [T] {
3905 Repr { raw: FatPtr { data, len} }.rust_mut
3908 /// Converts a reference to T into a slice of length 1 (without copying).
3909 #[stable(feature = "from_ref", since = "1.28.0")]
3910 pub fn from_ref<T>(s: &T) -> &[T] {
3912 from_raw_parts(s, 1)
3916 /// Converts a reference to T into a slice of length 1 (without copying).
3917 #[stable(feature = "from_ref", since = "1.28.0")]
3918 pub fn from_mut<T>(s: &mut T) -> &mut [T] {
3920 from_raw_parts_mut(s, 1)
3924 // This function is public only because there is no other way to unit test heapsort.
3925 #[unstable(feature = "sort_internals", reason = "internal to sort module", issue = "0")]
3927 pub fn heapsort<T, F>(v: &mut [T], mut is_less: F)
3928 where F: FnMut(&T, &T) -> bool
3930 sort::heapsort(v, &mut is_less);
3934 // Comparison traits
3938 /// Calls implementation provided memcmp.
3940 /// Interprets the data as u8.
3942 /// Returns 0 for equal, < 0 for less than and > 0 for greater
3944 // FIXME(#32610): Return type should be c_int
3945 fn memcmp(s1: *const u8, s2: *const u8, n: usize) -> i32;
3948 #[stable(feature = "rust1", since = "1.0.0")]
3949 impl<A, B> PartialEq<[B]> for [A] where A: PartialEq<B> {
3950 fn eq(&self, other: &[B]) -> bool {
3951 SlicePartialEq::equal(self, other)
3954 fn ne(&self, other: &[B]) -> bool {
3955 SlicePartialEq::not_equal(self, other)
3959 #[stable(feature = "rust1", since = "1.0.0")]
3960 impl<T: Eq> Eq for [T] {}
3962 /// Implements comparison of vectors lexicographically.
3963 #[stable(feature = "rust1", since = "1.0.0")]
3964 impl<T: Ord> Ord for [T] {
3965 fn cmp(&self, other: &[T]) -> Ordering {
3966 SliceOrd::compare(self, other)
3970 /// Implements comparison of vectors lexicographically.
3971 #[stable(feature = "rust1", since = "1.0.0")]
3972 impl<T: PartialOrd> PartialOrd for [T] {
3973 fn partial_cmp(&self, other: &[T]) -> Option<Ordering> {
3974 SlicePartialOrd::partial_compare(self, other)
3979 // intermediate trait for specialization of slice's PartialEq
3980 trait SlicePartialEq<B> {
3981 fn equal(&self, other: &[B]) -> bool;
3983 fn not_equal(&self, other: &[B]) -> bool { !self.equal(other) }
3986 // Generic slice equality
3987 impl<A, B> SlicePartialEq<B> for [A]
3988 where A: PartialEq<B>
3990 default fn equal(&self, other: &[B]) -> bool {
3991 if self.len() != other.len() {
3995 for i in 0..self.len() {
3996 if !self[i].eq(&other[i]) {
4005 // Use memcmp for bytewise equality when the types allow
4006 impl<A> SlicePartialEq<A> for [A]
4007 where A: PartialEq<A> + BytewiseEquality
4009 fn equal(&self, other: &[A]) -> bool {
4010 if self.len() != other.len() {
4013 if self.as_ptr() == other.as_ptr() {
4017 let size = mem::size_of_val(self);
4018 memcmp(self.as_ptr() as *const u8,
4019 other.as_ptr() as *const u8, size) == 0
4025 // intermediate trait for specialization of slice's PartialOrd
4026 trait SlicePartialOrd<B> {
4027 fn partial_compare(&self, other: &[B]) -> Option<Ordering>;
4030 impl<A> SlicePartialOrd<A> for [A]
4033 default fn partial_compare(&self, other: &[A]) -> Option<Ordering> {
4034 let l = cmp::min(self.len(), other.len());
4036 // Slice to the loop iteration range to enable bound check
4037 // elimination in the compiler
4038 let lhs = &self[..l];
4039 let rhs = &other[..l];
4042 match lhs[i].partial_cmp(&rhs[i]) {
4043 Some(Ordering::Equal) => (),
4044 non_eq => return non_eq,
4048 self.len().partial_cmp(&other.len())
4052 impl<A> SlicePartialOrd<A> for [A]
4055 default fn partial_compare(&self, other: &[A]) -> Option<Ordering> {
4056 Some(SliceOrd::compare(self, other))
4061 // intermediate trait for specialization of slice's Ord
4063 fn compare(&self, other: &[B]) -> Ordering;
4066 impl<A> SliceOrd<A> for [A]
4069 default fn compare(&self, other: &[A]) -> Ordering {
4070 let l = cmp::min(self.len(), other.len());
4072 // Slice to the loop iteration range to enable bound check
4073 // elimination in the compiler
4074 let lhs = &self[..l];
4075 let rhs = &other[..l];
4078 match lhs[i].cmp(&rhs[i]) {
4079 Ordering::Equal => (),
4080 non_eq => return non_eq,
4084 self.len().cmp(&other.len())
4088 // memcmp compares a sequence of unsigned bytes lexicographically.
4089 // this matches the order we want for [u8], but no others (not even [i8]).
4090 impl SliceOrd<u8> for [u8] {
4092 fn compare(&self, other: &[u8]) -> Ordering {
4093 let order = unsafe {
4094 memcmp(self.as_ptr(), other.as_ptr(),
4095 cmp::min(self.len(), other.len()))
4098 self.len().cmp(&other.len())
4099 } else if order < 0 {
4108 /// Trait implemented for types that can be compared for equality using
4109 /// their bytewise representation
4110 trait BytewiseEquality { }
4112 macro_rules! impl_marker_for {
4113 ($traitname:ident, $($ty:ty)*) => {
4115 impl $traitname for $ty { }
4120 impl_marker_for!(BytewiseEquality,
4121 u8 i8 u16 i16 u32 i32 u64 i64 usize isize char bool);
4124 unsafe impl<'a, T> TrustedRandomAccess for Iter<'a, T> {
4125 unsafe fn get_unchecked(&mut self, i: usize) -> &'a T {
4126 &*self.ptr.offset(i as isize)
4128 fn may_have_side_effect() -> bool { false }
4132 unsafe impl<'a, T> TrustedRandomAccess for IterMut<'a, T> {
4133 unsafe fn get_unchecked(&mut self, i: usize) -> &'a mut T {
4134 &mut *self.ptr.offset(i as isize)
4136 fn may_have_side_effect() -> bool { false }
4139 trait SliceContains: Sized {
4140 fn slice_contains(&self, x: &[Self]) -> bool;
4143 impl<T> SliceContains for T where T: PartialEq {
4144 default fn slice_contains(&self, x: &[Self]) -> bool {
4145 x.iter().any(|y| *y == *self)
4149 impl SliceContains for u8 {
4150 fn slice_contains(&self, x: &[Self]) -> bool {
4151 memchr::memchr(*self, x).is_some()
4155 impl SliceContains for i8 {
4156 fn slice_contains(&self, x: &[Self]) -> bool {
4157 let byte = *self as u8;
4158 let bytes: &[u8] = unsafe { from_raw_parts(x.as_ptr() as *const u8, x.len()) };
4159 memchr::memchr(byte, bytes).is_some()