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 reexported 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.
39 use cmp::Ordering::{self, Less, Equal, Greater};
42 use intrinsics::assume;
44 use ops::{FnMut, self};
46 use option::Option::{None, Some};
48 use result::Result::{Ok, Err};
51 use marker::{Copy, Send, Sync, Sized, self};
52 use iter_private::TrustedRandomAccess;
67 /// Extension methods for slices.
68 #[unstable(feature = "core_slice_ext",
69 reason = "stable interface provided by `impl [T]` in later crates",
71 #[allow(missing_docs)] // documented elsewhere
75 #[stable(feature = "core", since = "1.6.0")]
76 fn split_at(&self, mid: usize) -> (&[Self::Item], &[Self::Item]);
78 #[stable(feature = "core", since = "1.6.0")]
79 fn iter(&self) -> Iter<Self::Item>;
81 #[stable(feature = "core", since = "1.6.0")]
82 fn split<P>(&self, pred: P) -> Split<Self::Item, P>
83 where P: FnMut(&Self::Item) -> bool;
85 #[unstable(feature = "slice_rsplit", issue = "41020")]
86 fn rsplit<P>(&self, pred: P) -> RSplit<Self::Item, P>
87 where P: FnMut(&Self::Item) -> bool;
89 #[stable(feature = "core", since = "1.6.0")]
90 fn splitn<P>(&self, n: usize, pred: P) -> SplitN<Self::Item, P>
91 where P: FnMut(&Self::Item) -> bool;
93 #[stable(feature = "core", since = "1.6.0")]
94 fn rsplitn<P>(&self, n: usize, pred: P) -> RSplitN<Self::Item, P>
95 where P: FnMut(&Self::Item) -> bool;
97 #[stable(feature = "core", since = "1.6.0")]
98 fn windows(&self, size: usize) -> Windows<Self::Item>;
100 #[stable(feature = "core", since = "1.6.0")]
101 fn chunks(&self, size: usize) -> Chunks<Self::Item>;
103 #[stable(feature = "core", since = "1.6.0")]
104 fn get<I>(&self, index: I) -> Option<&I::Output>
105 where I: SliceIndex<Self>;
106 #[stable(feature = "core", since = "1.6.0")]
107 fn first(&self) -> Option<&Self::Item>;
109 #[stable(feature = "core", since = "1.6.0")]
110 fn split_first(&self) -> Option<(&Self::Item, &[Self::Item])>;
112 #[stable(feature = "core", since = "1.6.0")]
113 fn split_last(&self) -> Option<(&Self::Item, &[Self::Item])>;
115 #[stable(feature = "core", since = "1.6.0")]
116 fn last(&self) -> Option<&Self::Item>;
118 #[stable(feature = "core", since = "1.6.0")]
119 unsafe fn get_unchecked<I>(&self, index: I) -> &I::Output
120 where I: SliceIndex<Self>;
121 #[stable(feature = "core", since = "1.6.0")]
122 fn as_ptr(&self) -> *const Self::Item;
124 #[stable(feature = "core", since = "1.6.0")]
125 fn binary_search<Q: ?Sized>(&self, x: &Q) -> Result<usize, usize>
126 where Self::Item: Borrow<Q>,
129 #[stable(feature = "core", since = "1.6.0")]
130 fn binary_search_by<'a, F>(&'a self, f: F) -> Result<usize, usize>
131 where F: FnMut(&'a Self::Item) -> Ordering;
133 #[stable(feature = "slice_binary_search_by_key", since = "1.10.0")]
134 fn binary_search_by_key<'a, B, F, Q: ?Sized>(&'a self, b: &Q, f: F) -> Result<usize, usize>
135 where F: FnMut(&'a Self::Item) -> B,
139 #[stable(feature = "core", since = "1.6.0")]
140 fn len(&self) -> usize;
142 #[stable(feature = "core", since = "1.6.0")]
143 fn is_empty(&self) -> bool { self.len() == 0 }
145 #[stable(feature = "core", since = "1.6.0")]
146 fn get_mut<I>(&mut self, index: I) -> Option<&mut I::Output>
147 where I: SliceIndex<Self>;
148 #[stable(feature = "core", since = "1.6.0")]
149 fn iter_mut(&mut self) -> IterMut<Self::Item>;
151 #[stable(feature = "core", since = "1.6.0")]
152 fn first_mut(&mut self) -> Option<&mut Self::Item>;
154 #[stable(feature = "core", since = "1.6.0")]
155 fn split_first_mut(&mut self) -> Option<(&mut Self::Item, &mut [Self::Item])>;
157 #[stable(feature = "core", since = "1.6.0")]
158 fn split_last_mut(&mut self) -> Option<(&mut Self::Item, &mut [Self::Item])>;
160 #[stable(feature = "core", since = "1.6.0")]
161 fn last_mut(&mut self) -> Option<&mut Self::Item>;
163 #[stable(feature = "core", since = "1.6.0")]
164 fn split_mut<P>(&mut self, pred: P) -> SplitMut<Self::Item, P>
165 where P: FnMut(&Self::Item) -> bool;
167 #[unstable(feature = "slice_rsplit", issue = "41020")]
168 fn rsplit_mut<P>(&mut self, pred: P) -> RSplitMut<Self::Item, P>
169 where P: FnMut(&Self::Item) -> bool;
171 #[stable(feature = "core", since = "1.6.0")]
172 fn splitn_mut<P>(&mut self, n: usize, pred: P) -> SplitNMut<Self::Item, P>
173 where P: FnMut(&Self::Item) -> bool;
175 #[stable(feature = "core", since = "1.6.0")]
176 fn rsplitn_mut<P>(&mut self, n: usize, pred: P) -> RSplitNMut<Self::Item, P>
177 where P: FnMut(&Self::Item) -> bool;
179 #[stable(feature = "core", since = "1.6.0")]
180 fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<Self::Item>;
182 #[stable(feature = "core", since = "1.6.0")]
183 fn swap(&mut self, a: usize, b: usize);
185 #[stable(feature = "core", since = "1.6.0")]
186 fn split_at_mut(&mut self, mid: usize) -> (&mut [Self::Item], &mut [Self::Item]);
188 #[stable(feature = "core", since = "1.6.0")]
189 fn reverse(&mut self);
191 #[stable(feature = "core", since = "1.6.0")]
192 unsafe fn get_unchecked_mut<I>(&mut self, index: I) -> &mut I::Output
193 where I: SliceIndex<Self>;
194 #[stable(feature = "core", since = "1.6.0")]
195 fn as_mut_ptr(&mut self) -> *mut Self::Item;
197 #[stable(feature = "core", since = "1.6.0")]
198 fn contains(&self, x: &Self::Item) -> bool where Self::Item: PartialEq;
200 #[stable(feature = "core", since = "1.6.0")]
201 fn starts_with(&self, needle: &[Self::Item]) -> bool where Self::Item: PartialEq;
203 #[stable(feature = "core", since = "1.6.0")]
204 fn ends_with(&self, needle: &[Self::Item]) -> bool where Self::Item: PartialEq;
206 #[unstable(feature = "slice_rotate", issue = "41891")]
207 fn rotate(&mut self, mid: usize);
209 #[stable(feature = "clone_from_slice", since = "1.7.0")]
210 fn clone_from_slice(&mut self, src: &[Self::Item]) where Self::Item: Clone;
212 #[stable(feature = "copy_from_slice", since = "1.9.0")]
213 fn copy_from_slice(&mut self, src: &[Self::Item]) where Self::Item: Copy;
215 #[stable(feature = "sort_unstable", since = "1.20.0")]
216 fn sort_unstable(&mut self)
217 where Self::Item: Ord;
219 #[stable(feature = "sort_unstable", since = "1.20.0")]
220 fn sort_unstable_by<F>(&mut self, compare: F)
221 where F: FnMut(&Self::Item, &Self::Item) -> Ordering;
223 #[stable(feature = "sort_unstable", since = "1.20.0")]
224 fn sort_unstable_by_key<B, F>(&mut self, f: F)
225 where F: FnMut(&Self::Item) -> B,
229 // Use macros to be generic over const/mut
230 macro_rules! slice_offset {
231 ($ptr:expr, $by:expr) => {{
233 if size_from_ptr(ptr) == 0 {
234 (ptr as *mut i8).wrapping_offset($by) as _
241 // make a &T from a *const T
242 macro_rules! make_ref {
245 if size_from_ptr(ptr) == 0 {
246 // Use a non-null pointer value
254 // make a &mut T from a *mut T
255 macro_rules! make_ref_mut {
258 if size_from_ptr(ptr) == 0 {
259 // Use a non-null pointer value
267 #[unstable(feature = "core_slice_ext",
268 reason = "stable interface provided by `impl [T]` in later crates",
270 impl<T> SliceExt for [T] {
274 fn split_at(&self, mid: usize) -> (&[T], &[T]) {
275 (&self[..mid], &self[mid..])
279 fn iter(&self) -> Iter<T> {
281 let p = if mem::size_of::<T>() == 0 {
284 let p = self.as_ptr();
285 assume(!p.is_null());
291 end: slice_offset!(p, self.len() as isize),
292 _marker: marker::PhantomData
298 fn split<P>(&self, pred: P) -> Split<T, P>
299 where P: FnMut(&T) -> bool
309 fn rsplit<P>(&self, pred: P) -> RSplit<T, P>
310 where P: FnMut(&T) -> bool
312 RSplit { inner: self.split(pred) }
316 fn splitn<P>(&self, n: usize, pred: P) -> SplitN<T, P>
317 where P: FnMut(&T) -> bool
320 inner: GenericSplitN {
321 iter: self.split(pred),
328 fn rsplitn<P>(&self, n: usize, pred: P) -> RSplitN<T, P>
329 where P: FnMut(&T) -> bool
332 inner: GenericSplitN {
333 iter: self.rsplit(pred),
340 fn windows(&self, size: usize) -> Windows<T> {
342 Windows { v: self, size: size }
346 fn chunks(&self, size: usize) -> Chunks<T> {
348 Chunks { v: self, size: size }
352 fn get<I>(&self, index: I) -> Option<&I::Output>
353 where I: SliceIndex<[T]>
359 fn first(&self) -> Option<&T> {
360 if self.is_empty() { None } else { Some(&self[0]) }
364 fn split_first(&self) -> Option<(&T, &[T])> {
365 if self.is_empty() { None } else { Some((&self[0], &self[1..])) }
369 fn split_last(&self) -> Option<(&T, &[T])> {
370 let len = self.len();
371 if len == 0 { None } else { Some((&self[len - 1], &self[..(len - 1)])) }
375 fn last(&self) -> Option<&T> {
376 if self.is_empty() { None } else { Some(&self[self.len() - 1]) }
380 unsafe fn get_unchecked<I>(&self, index: I) -> &I::Output
381 where I: SliceIndex<[T]>
383 index.get_unchecked(self)
387 fn as_ptr(&self) -> *const T {
388 self as *const [T] as *const T
391 fn binary_search_by<'a, F>(&'a self, mut f: F) -> Result<usize, usize>
392 where F: FnMut(&'a T) -> Ordering
394 let mut base = 0usize;
398 let (head, tail) = s.split_at(s.len() >> 1);
404 base += head.len() + 1;
408 Equal => return Ok(base + head.len()),
414 fn len(&self) -> usize {
416 mem::transmute::<&[T], Repr<T>>(self).len
421 fn get_mut<I>(&mut self, index: I) -> Option<&mut I::Output>
422 where I: SliceIndex<[T]>
428 fn split_at_mut(&mut self, mid: usize) -> (&mut [T], &mut [T]) {
429 let len = self.len();
430 let ptr = self.as_mut_ptr();
435 (from_raw_parts_mut(ptr, mid),
436 from_raw_parts_mut(ptr.offset(mid as isize), len - mid))
441 fn iter_mut(&mut self) -> IterMut<T> {
443 let p = if mem::size_of::<T>() == 0 {
446 let p = self.as_mut_ptr();
447 assume(!p.is_null());
453 end: slice_offset!(p, self.len() as isize),
454 _marker: marker::PhantomData
460 fn last_mut(&mut self) -> Option<&mut T> {
461 let len = self.len();
462 if len == 0 { return None; }
463 Some(&mut self[len - 1])
467 fn first_mut(&mut self) -> Option<&mut T> {
468 if self.is_empty() { None } else { Some(&mut self[0]) }
472 fn split_first_mut(&mut self) -> Option<(&mut T, &mut [T])> {
473 if self.is_empty() { None } else {
474 let split = self.split_at_mut(1);
475 Some((&mut split.0[0], split.1))
480 fn split_last_mut(&mut self) -> Option<(&mut T, &mut [T])> {
481 let len = self.len();
482 if len == 0 { None } else {
483 let split = self.split_at_mut(len - 1);
484 Some((&mut split.1[0], split.0))
489 fn split_mut<P>(&mut self, pred: P) -> SplitMut<T, P>
490 where P: FnMut(&T) -> bool
492 SplitMut { v: self, pred: pred, finished: false }
496 fn rsplit_mut<P>(&mut self, pred: P) -> RSplitMut<T, P>
497 where P: FnMut(&T) -> bool
499 RSplitMut { inner: self.split_mut(pred) }
503 fn splitn_mut<P>(&mut self, n: usize, pred: P) -> SplitNMut<T, P>
504 where P: FnMut(&T) -> bool
507 inner: GenericSplitN {
508 iter: self.split_mut(pred),
515 fn rsplitn_mut<P>(&mut self, n: usize, pred: P) -> RSplitNMut<T, P> where
516 P: FnMut(&T) -> bool,
519 inner: GenericSplitN {
520 iter: self.rsplit_mut(pred),
527 fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<T> {
528 assert!(chunk_size > 0);
529 ChunksMut { v: self, chunk_size: chunk_size }
533 fn swap(&mut self, a: usize, b: usize) {
535 // Can't take two mutable loans from one vector, so instead just cast
536 // them to their raw pointers to do the swap
537 let pa: *mut T = &mut self[a];
538 let pb: *mut T = &mut self[b];
543 fn reverse(&mut self) {
544 let mut i: usize = 0;
547 // For very small types, all the individual reads in the normal
548 // path perform poorly. We can do better, given efficient unaligned
549 // load/store, by loading a larger chunk and reversing a register.
551 // Ideally LLVM would do this for us, as it knows better than we do
552 // whether unaligned reads are efficient (since that changes between
553 // different ARM versions, for example) and what the best chunk size
554 // would be. Unfortunately, as of LLVM 4.0 (2017-05) it only unrolls
555 // the loop, so we need to do this ourselves. (Hypothesis: reverse
556 // is troublesome because the sides can be aligned differently --
557 // will be, when the length is odd -- so there's no way of emitting
558 // pre- and postludes to use fully-aligned SIMD in the middle.)
561 cfg!(any(target_arch = "x86", target_arch = "x86_64"));
563 if fast_unaligned && mem::size_of::<T>() == 1 {
564 // Use the llvm.bswap intrinsic to reverse u8s in a usize
565 let chunk = mem::size_of::<usize>();
566 while i + chunk - 1 < ln / 2 {
568 let pa: *mut T = self.get_unchecked_mut(i);
569 let pb: *mut T = self.get_unchecked_mut(ln - i - chunk);
570 let va = ptr::read_unaligned(pa as *mut usize);
571 let vb = ptr::read_unaligned(pb as *mut usize);
572 ptr::write_unaligned(pa as *mut usize, vb.swap_bytes());
573 ptr::write_unaligned(pb as *mut usize, va.swap_bytes());
579 if fast_unaligned && mem::size_of::<T>() == 2 {
580 // Use rotate-by-16 to reverse u16s in a u32
581 let chunk = mem::size_of::<u32>() / 2;
582 while i + chunk - 1 < ln / 2 {
584 let pa: *mut T = self.get_unchecked_mut(i);
585 let pb: *mut T = self.get_unchecked_mut(ln - i - chunk);
586 let va = ptr::read_unaligned(pa as *mut u32);
587 let vb = ptr::read_unaligned(pb as *mut u32);
588 ptr::write_unaligned(pa as *mut u32, vb.rotate_left(16));
589 ptr::write_unaligned(pb as *mut u32, va.rotate_left(16));
596 // Unsafe swap to avoid the bounds check in safe swap.
598 let pa: *mut T = self.get_unchecked_mut(i);
599 let pb: *mut T = self.get_unchecked_mut(ln - i - 1);
607 unsafe fn get_unchecked_mut<I>(&mut self, index: I) -> &mut I::Output
608 where I: SliceIndex<[T]>
610 index.get_unchecked_mut(self)
614 fn as_mut_ptr(&mut self) -> *mut T {
615 self as *mut [T] as *mut T
619 fn contains(&self, x: &T) -> bool where T: PartialEq {
620 self.iter().any(|elt| *x == *elt)
624 fn starts_with(&self, needle: &[T]) -> bool where T: PartialEq {
625 let n = needle.len();
626 self.len() >= n && needle == &self[..n]
630 fn ends_with(&self, needle: &[T]) -> bool where T: PartialEq {
631 let (m, n) = (self.len(), needle.len());
632 m >= n && needle == &self[m-n..]
635 fn binary_search<Q: ?Sized>(&self, x: &Q) -> Result<usize, usize>
639 self.binary_search_by(|p| p.borrow().cmp(x))
642 fn rotate(&mut self, mid: usize) {
643 assert!(mid <= self.len());
644 let k = self.len() - mid;
647 let p = self.as_mut_ptr();
648 rotate::ptr_rotate(mid, p.offset(mid as isize), k);
653 fn clone_from_slice(&mut self, src: &[T]) where T: Clone {
654 assert!(self.len() == src.len(),
655 "destination and source slices have different lengths");
656 // NOTE: We need to explicitly slice them to the same length
657 // for bounds checking to be elided, and the optimizer will
658 // generate memcpy for simple cases (for example T = u8).
659 let len = self.len();
660 let src = &src[..len];
662 self[i].clone_from(&src[i]);
667 fn copy_from_slice(&mut self, src: &[T]) where T: Copy {
668 assert!(self.len() == src.len(),
669 "destination and source slices have different lengths");
671 ptr::copy_nonoverlapping(
672 src.as_ptr(), self.as_mut_ptr(), self.len());
677 fn binary_search_by_key<'a, B, F, Q: ?Sized>(&'a self, b: &Q, mut f: F) -> Result<usize, usize>
678 where F: FnMut(&'a Self::Item) -> B,
682 self.binary_search_by(|k| f(k).borrow().cmp(b))
686 fn sort_unstable(&mut self)
687 where Self::Item: Ord
689 sort::quicksort(self, |a, b| a.lt(b));
693 fn sort_unstable_by<F>(&mut self, mut compare: F)
694 where F: FnMut(&Self::Item, &Self::Item) -> Ordering
696 sort::quicksort(self, |a, b| compare(a, b) == Ordering::Less);
700 fn sort_unstable_by_key<B, F>(&mut self, mut f: F)
701 where F: FnMut(&Self::Item) -> B,
704 sort::quicksort(self, |a, b| f(a).lt(&f(b)));
708 #[stable(feature = "rust1", since = "1.0.0")]
709 #[rustc_on_unimplemented = "slice indices are of type `usize` or ranges of `usize`"]
710 impl<T, I> ops::Index<I> for [T]
711 where I: SliceIndex<[T]>
713 type Output = I::Output;
716 fn index(&self, index: I) -> &I::Output {
721 #[stable(feature = "rust1", since = "1.0.0")]
722 #[rustc_on_unimplemented = "slice indices are of type `usize` or ranges of `usize`"]
723 impl<T, I> ops::IndexMut<I> for [T]
724 where I: SliceIndex<[T]>
727 fn index_mut(&mut self, index: I) -> &mut I::Output {
728 index.index_mut(self)
734 fn slice_index_len_fail(index: usize, len: usize) -> ! {
735 panic!("index {} out of range for slice of length {}", index, len);
740 fn slice_index_order_fail(index: usize, end: usize) -> ! {
741 panic!("slice index starts at {} but ends at {}", index, end);
744 /// A helper trait used for indexing operations.
745 #[unstable(feature = "slice_get_slice", issue = "35729")]
746 #[rustc_on_unimplemented = "slice indices are of type `usize` or ranges of `usize`"]
747 pub trait SliceIndex<T: ?Sized> {
748 /// The output type returned by methods.
751 /// Returns a shared reference to the output at this location, if in
753 fn get(self, slice: &T) -> Option<&Self::Output>;
755 /// Returns a mutable reference to the output at this location, if in
757 fn get_mut(self, slice: &mut T) -> Option<&mut Self::Output>;
759 /// Returns a shared reference to the output at this location, without
760 /// performing any bounds checking.
761 unsafe fn get_unchecked(self, slice: &T) -> &Self::Output;
763 /// Returns a mutable reference to the output at this location, without
764 /// performing any bounds checking.
765 unsafe fn get_unchecked_mut(self, slice: &mut T) -> &mut Self::Output;
767 /// Returns a shared reference to the output at this location, panicking
768 /// if out of bounds.
769 fn index(self, slice: &T) -> &Self::Output;
771 /// Returns a mutable reference to the output at this location, panicking
772 /// if out of bounds.
773 fn index_mut(self, slice: &mut T) -> &mut Self::Output;
776 #[stable(feature = "slice-get-slice-impls", since = "1.15.0")]
777 impl<T> SliceIndex<[T]> for usize {
781 fn get(self, slice: &[T]) -> Option<&T> {
782 if self < slice.len() {
784 Some(self.get_unchecked(slice))
792 fn get_mut(self, slice: &mut [T]) -> Option<&mut T> {
793 if self < slice.len() {
795 Some(self.get_unchecked_mut(slice))
803 unsafe fn get_unchecked(self, slice: &[T]) -> &T {
804 &*slice.as_ptr().offset(self as isize)
808 unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut T {
809 &mut *slice.as_mut_ptr().offset(self as isize)
813 fn index(self, slice: &[T]) -> &T {
814 // NB: use intrinsic indexing
819 fn index_mut(self, slice: &mut [T]) -> &mut T {
820 // NB: use intrinsic indexing
825 #[stable(feature = "slice-get-slice-impls", since = "1.15.0")]
826 impl<T> SliceIndex<[T]> for ops::Range<usize> {
830 fn get(self, slice: &[T]) -> Option<&[T]> {
831 if self.start > self.end || self.end > slice.len() {
835 Some(self.get_unchecked(slice))
841 fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
842 if self.start > self.end || self.end > slice.len() {
846 Some(self.get_unchecked_mut(slice))
852 unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
853 from_raw_parts(slice.as_ptr().offset(self.start as isize), self.end - self.start)
857 unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
858 from_raw_parts_mut(slice.as_mut_ptr().offset(self.start as isize), self.end - self.start)
862 fn index(self, slice: &[T]) -> &[T] {
863 if self.start > self.end {
864 slice_index_order_fail(self.start, self.end);
865 } else if self.end > slice.len() {
866 slice_index_len_fail(self.end, slice.len());
869 self.get_unchecked(slice)
874 fn index_mut(self, slice: &mut [T]) -> &mut [T] {
875 if self.start > self.end {
876 slice_index_order_fail(self.start, self.end);
877 } else if self.end > slice.len() {
878 slice_index_len_fail(self.end, slice.len());
881 self.get_unchecked_mut(slice)
886 #[stable(feature = "slice-get-slice-impls", since = "1.15.0")]
887 impl<T> SliceIndex<[T]> for ops::RangeTo<usize> {
891 fn get(self, slice: &[T]) -> Option<&[T]> {
892 (0..self.end).get(slice)
896 fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
897 (0..self.end).get_mut(slice)
901 unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
902 (0..self.end).get_unchecked(slice)
906 unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
907 (0..self.end).get_unchecked_mut(slice)
911 fn index(self, slice: &[T]) -> &[T] {
912 (0..self.end).index(slice)
916 fn index_mut(self, slice: &mut [T]) -> &mut [T] {
917 (0..self.end).index_mut(slice)
921 #[stable(feature = "slice-get-slice-impls", since = "1.15.0")]
922 impl<T> SliceIndex<[T]> for ops::RangeFrom<usize> {
926 fn get(self, slice: &[T]) -> Option<&[T]> {
927 (self.start..slice.len()).get(slice)
931 fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
932 (self.start..slice.len()).get_mut(slice)
936 unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
937 (self.start..slice.len()).get_unchecked(slice)
941 unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
942 (self.start..slice.len()).get_unchecked_mut(slice)
946 fn index(self, slice: &[T]) -> &[T] {
947 (self.start..slice.len()).index(slice)
951 fn index_mut(self, slice: &mut [T]) -> &mut [T] {
952 (self.start..slice.len()).index_mut(slice)
956 #[stable(feature = "slice-get-slice-impls", since = "1.15.0")]
957 impl<T> SliceIndex<[T]> for ops::RangeFull {
961 fn get(self, slice: &[T]) -> Option<&[T]> {
966 fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
971 unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
976 unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
981 fn index(self, slice: &[T]) -> &[T] {
986 fn index_mut(self, slice: &mut [T]) -> &mut [T] {
992 #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
993 impl<T> SliceIndex<[T]> for ops::RangeInclusive<usize> {
997 fn get(self, slice: &[T]) -> Option<&[T]> {
998 if self.end == usize::max_value() { None }
999 else { (self.start..self.end + 1).get(slice) }
1003 fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
1004 if self.end == usize::max_value() { None }
1005 else { (self.start..self.end + 1).get_mut(slice) }
1009 unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
1010 (self.start..self.end + 1).get_unchecked(slice)
1014 unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
1015 (self.start..self.end + 1).get_unchecked_mut(slice)
1019 fn index(self, slice: &[T]) -> &[T] {
1020 assert!(self.end != usize::max_value(),
1021 "attempted to index slice up to maximum usize");
1022 (self.start..self.end + 1).index(slice)
1026 fn index_mut(self, slice: &mut [T]) -> &mut [T] {
1027 assert!(self.end != usize::max_value(),
1028 "attempted to index slice up to maximum usize");
1029 (self.start..self.end + 1).index_mut(slice)
1033 #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
1034 impl<T> SliceIndex<[T]> for ops::RangeToInclusive<usize> {
1038 fn get(self, slice: &[T]) -> Option<&[T]> {
1039 (0...self.end).get(slice)
1043 fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
1044 (0...self.end).get_mut(slice)
1048 unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
1049 (0...self.end).get_unchecked(slice)
1053 unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
1054 (0...self.end).get_unchecked_mut(slice)
1058 fn index(self, slice: &[T]) -> &[T] {
1059 (0...self.end).index(slice)
1063 fn index_mut(self, slice: &mut [T]) -> &mut [T] {
1064 (0...self.end).index_mut(slice)
1068 ////////////////////////////////////////////////////////////////////////////////
1070 ////////////////////////////////////////////////////////////////////////////////
1072 #[stable(feature = "rust1", since = "1.0.0")]
1073 impl<'a, T> Default for &'a [T] {
1074 /// Creates an empty slice.
1075 fn default() -> &'a [T] { &[] }
1078 #[stable(feature = "mut_slice_default", since = "1.5.0")]
1079 impl<'a, T> Default for &'a mut [T] {
1080 /// Creates a mutable empty slice.
1081 fn default() -> &'a mut [T] { &mut [] }
1088 #[stable(feature = "rust1", since = "1.0.0")]
1089 impl<'a, T> IntoIterator for &'a [T] {
1091 type IntoIter = Iter<'a, T>;
1093 fn into_iter(self) -> Iter<'a, T> {
1098 #[stable(feature = "rust1", since = "1.0.0")]
1099 impl<'a, T> IntoIterator for &'a mut [T] {
1100 type Item = &'a mut T;
1101 type IntoIter = IterMut<'a, T>;
1103 fn into_iter(self) -> IterMut<'a, T> {
1109 fn size_from_ptr<T>(_: *const T) -> usize {
1113 // The shared definition of the `Iter` and `IterMut` iterators
1114 macro_rules! iterator {
1115 (struct $name:ident -> $ptr:ty, $elem:ty, $mkref:ident) => {
1116 #[stable(feature = "rust1", since = "1.0.0")]
1117 impl<'a, T> Iterator for $name<'a, T> {
1121 fn next(&mut self) -> Option<$elem> {
1122 // could be implemented with slices, but this avoids bounds checks
1124 if mem::size_of::<T>() != 0 {
1125 assume(!self.ptr.is_null());
1126 assume(!self.end.is_null());
1128 if self.ptr == self.end {
1131 Some($mkref!(self.ptr.post_inc()))
1137 fn size_hint(&self) -> (usize, Option<usize>) {
1138 let exact = ptrdistance(self.ptr, self.end);
1139 (exact, Some(exact))
1143 fn count(self) -> usize {
1148 fn nth(&mut self, n: usize) -> Option<$elem> {
1149 // Call helper method. Can't put the definition here because mut versus const.
1154 fn last(mut self) -> Option<$elem> {
1158 fn all<F>(&mut self, mut predicate: F) -> bool
1159 where F: FnMut(Self::Item) -> bool,
1161 self.search_while(true, move |elt| {
1163 SearchWhile::Continue
1165 SearchWhile::Done(false)
1170 fn any<F>(&mut self, mut predicate: F) -> bool
1171 where F: FnMut(Self::Item) -> bool,
1173 !self.all(move |elt| !predicate(elt))
1176 fn find<F>(&mut self, mut predicate: F) -> Option<Self::Item>
1177 where F: FnMut(&Self::Item) -> bool,
1179 self.search_while(None, move |elt| {
1180 if predicate(&elt) {
1181 SearchWhile::Done(Some(elt))
1183 SearchWhile::Continue
1188 fn position<F>(&mut self, mut predicate: F) -> Option<usize>
1189 where F: FnMut(Self::Item) -> bool,
1192 self.search_while(None, move |elt| {
1194 SearchWhile::Done(Some(index))
1197 SearchWhile::Continue
1202 fn rposition<F>(&mut self, mut predicate: F) -> Option<usize>
1203 where F: FnMut(Self::Item) -> bool,
1205 let mut index = self.len();
1206 self.rsearch_while(None, move |elt| {
1209 SearchWhile::Done(Some(index))
1211 SearchWhile::Continue
1217 #[stable(feature = "rust1", since = "1.0.0")]
1218 impl<'a, T> DoubleEndedIterator for $name<'a, T> {
1220 fn next_back(&mut self) -> Option<$elem> {
1221 // could be implemented with slices, but this avoids bounds checks
1223 if mem::size_of::<T>() != 0 {
1224 assume(!self.ptr.is_null());
1225 assume(!self.end.is_null());
1227 if self.end == self.ptr {
1230 Some($mkref!(self.end.pre_dec()))
1235 fn rfind<F>(&mut self, mut predicate: F) -> Option<Self::Item>
1236 where F: FnMut(&Self::Item) -> bool,
1238 self.rsearch_while(None, move |elt| {
1239 if predicate(&elt) {
1240 SearchWhile::Done(Some(elt))
1242 SearchWhile::Continue
1249 // search_while is a generalization of the internal iteration methods.
1250 impl<'a, T> $name<'a, T> {
1251 // search through the iterator's element using the closure `g`.
1252 // if no element was found, return `default`.
1253 fn search_while<Acc, G>(&mut self, default: Acc, mut g: G) -> Acc
1255 G: FnMut($elem) -> SearchWhile<Acc>
1257 // manual unrolling is needed when there are conditional exits from the loop
1259 while ptrdistance(self.ptr, self.end) >= 4 {
1260 search_while!(g($mkref!(self.ptr.post_inc())));
1261 search_while!(g($mkref!(self.ptr.post_inc())));
1262 search_while!(g($mkref!(self.ptr.post_inc())));
1263 search_while!(g($mkref!(self.ptr.post_inc())));
1265 while self.ptr != self.end {
1266 search_while!(g($mkref!(self.ptr.post_inc())));
1272 fn rsearch_while<Acc, G>(&mut self, default: Acc, mut g: G) -> Acc
1274 G: FnMut($elem) -> SearchWhile<Acc>
1277 while ptrdistance(self.ptr, self.end) >= 4 {
1278 search_while!(g($mkref!(self.end.pre_dec())));
1279 search_while!(g($mkref!(self.end.pre_dec())));
1280 search_while!(g($mkref!(self.end.pre_dec())));
1281 search_while!(g($mkref!(self.end.pre_dec())));
1283 while self.ptr != self.end {
1284 search_while!(g($mkref!(self.end.pre_dec())));
1293 macro_rules! make_slice {
1294 ($start: expr, $end: expr) => {{
1296 let diff = ($end as usize).wrapping_sub(start as usize);
1297 if size_from_ptr(start) == 0 {
1298 // use a non-null pointer value
1299 unsafe { from_raw_parts(1 as *const _, diff) }
1301 let len = diff / size_from_ptr(start);
1302 unsafe { from_raw_parts(start, len) }
1307 macro_rules! make_mut_slice {
1308 ($start: expr, $end: expr) => {{
1310 let diff = ($end as usize).wrapping_sub(start as usize);
1311 if size_from_ptr(start) == 0 {
1312 // use a non-null pointer value
1313 unsafe { from_raw_parts_mut(1 as *mut _, diff) }
1315 let len = diff / size_from_ptr(start);
1316 unsafe { from_raw_parts_mut(start, len) }
1321 // An enum used for controlling the execution of `.search_while()`.
1322 enum SearchWhile<T> {
1323 // Continue searching
1325 // Fold is complete and will return this value
1329 // helper macro for search while's control flow
1330 macro_rules! search_while {
1333 SearchWhile::Continue => { }
1334 SearchWhile::Done(done) => return done,
1339 /// Immutable slice iterator
1341 /// This struct is created by the [`iter`] method on [slices].
1348 /// // First, we declare a type which has `iter` method to get the `Iter` struct (&[usize here]):
1349 /// let slice = &[1, 2, 3];
1351 /// // Then, we iterate over it:
1352 /// for element in slice.iter() {
1353 /// println!("{}", element);
1357 /// [`iter`]: ../../std/primitive.slice.html#method.iter
1358 /// [slices]: ../../std/primitive.slice.html
1359 #[stable(feature = "rust1", since = "1.0.0")]
1360 pub struct Iter<'a, T: 'a> {
1363 _marker: marker::PhantomData<&'a T>,
1366 #[stable(feature = "core_impl_debug", since = "1.9.0")]
1367 impl<'a, T: 'a + fmt::Debug> fmt::Debug for Iter<'a, T> {
1368 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1369 f.debug_tuple("Iter")
1370 .field(&self.as_slice())
1375 #[stable(feature = "rust1", since = "1.0.0")]
1376 unsafe impl<'a, T: Sync> Sync for Iter<'a, T> {}
1377 #[stable(feature = "rust1", since = "1.0.0")]
1378 unsafe impl<'a, T: Sync> Send for Iter<'a, T> {}
1380 impl<'a, T> Iter<'a, T> {
1381 /// View the underlying data as a subslice of the original data.
1383 /// This has the same lifetime as the original slice, and so the
1384 /// iterator can continue to be used while this exists.
1391 /// // First, we declare a type which has the `iter` method to get the `Iter`
1392 /// // struct (&[usize here]):
1393 /// let slice = &[1, 2, 3];
1395 /// // Then, we get the iterator:
1396 /// let mut iter = slice.iter();
1397 /// // So if we print what `as_slice` method returns here, we have "[1, 2, 3]":
1398 /// println!("{:?}", iter.as_slice());
1400 /// // Next, we move to the second element of the slice:
1402 /// // Now `as_slice` returns "[2, 3]":
1403 /// println!("{:?}", iter.as_slice());
1405 #[stable(feature = "iter_to_slice", since = "1.4.0")]
1406 pub fn as_slice(&self) -> &'a [T] {
1407 make_slice!(self.ptr, self.end)
1410 // Helper function for Iter::nth
1411 fn iter_nth(&mut self, n: usize) -> Option<&'a T> {
1412 match self.as_slice().get(n) {
1413 Some(elem_ref) => unsafe {
1414 self.ptr = slice_offset!(self.ptr, (n as isize).wrapping_add(1));
1418 self.ptr = self.end;
1425 iterator!{struct Iter -> *const T, &'a T, make_ref}
1427 #[stable(feature = "rust1", since = "1.0.0")]
1428 impl<'a, T> ExactSizeIterator for Iter<'a, T> {
1429 fn is_empty(&self) -> bool {
1430 self.ptr == self.end
1434 #[unstable(feature = "fused", issue = "35602")]
1435 impl<'a, T> FusedIterator for Iter<'a, T> {}
1437 #[unstable(feature = "trusted_len", issue = "37572")]
1438 unsafe impl<'a, T> TrustedLen for Iter<'a, T> {}
1440 #[stable(feature = "rust1", since = "1.0.0")]
1441 impl<'a, T> Clone for Iter<'a, T> {
1442 fn clone(&self) -> Iter<'a, T> { Iter { ptr: self.ptr, end: self.end, _marker: self._marker } }
1445 #[stable(feature = "slice_iter_as_ref", since = "1.13.0")]
1446 impl<'a, T> AsRef<[T]> for Iter<'a, T> {
1447 fn as_ref(&self) -> &[T] {
1452 /// Mutable slice iterator.
1454 /// This struct is created by the [`iter_mut`] method on [slices].
1461 /// // First, we declare a type which has `iter_mut` method to get the `IterMut`
1462 /// // struct (&[usize here]):
1463 /// let mut slice = &mut [1, 2, 3];
1465 /// // Then, we iterate over it and increment each element value:
1466 /// for element in slice.iter_mut() {
1470 /// // We now have "[2, 3, 4]":
1471 /// println!("{:?}", slice);
1474 /// [`iter_mut`]: ../../std/primitive.slice.html#method.iter_mut
1475 /// [slices]: ../../std/primitive.slice.html
1476 #[stable(feature = "rust1", since = "1.0.0")]
1477 pub struct IterMut<'a, T: 'a> {
1480 _marker: marker::PhantomData<&'a mut T>,
1483 #[stable(feature = "core_impl_debug", since = "1.9.0")]
1484 impl<'a, T: 'a + fmt::Debug> fmt::Debug for IterMut<'a, T> {
1485 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1486 f.debug_tuple("IterMut")
1487 .field(&make_slice!(self.ptr, self.end))
1492 #[stable(feature = "rust1", since = "1.0.0")]
1493 unsafe impl<'a, T: Sync> Sync for IterMut<'a, T> {}
1494 #[stable(feature = "rust1", since = "1.0.0")]
1495 unsafe impl<'a, T: Send> Send for IterMut<'a, T> {}
1497 impl<'a, T> IterMut<'a, T> {
1498 /// View the underlying data as a subslice of the original data.
1500 /// To avoid creating `&mut` references that alias, this is forced
1501 /// to consume the iterator. Consider using the `Slice` and
1502 /// `SliceMut` implementations for obtaining slices with more
1503 /// restricted lifetimes that do not consume the iterator.
1510 /// // First, we declare a type which has `iter_mut` method to get the `IterMut`
1511 /// // struct (&[usize here]):
1512 /// let mut slice = &mut [1, 2, 3];
1515 /// // Then, we get the iterator:
1516 /// let mut iter = slice.iter_mut();
1517 /// // We move to next element:
1519 /// // So if we print what `into_slice` method returns here, we have "[2, 3]":
1520 /// println!("{:?}", iter.into_slice());
1523 /// // Now let's modify a value of the slice:
1525 /// // First we get back the iterator:
1526 /// let mut iter = slice.iter_mut();
1527 /// // We change the value of the first element of the slice returned by the `next` method:
1528 /// *iter.next().unwrap() += 1;
1530 /// // Now slice is "[2, 2, 3]":
1531 /// println!("{:?}", slice);
1533 #[stable(feature = "iter_to_slice", since = "1.4.0")]
1534 pub fn into_slice(self) -> &'a mut [T] {
1535 make_mut_slice!(self.ptr, self.end)
1538 // Helper function for IterMut::nth
1539 fn iter_nth(&mut self, n: usize) -> Option<&'a mut T> {
1540 match make_mut_slice!(self.ptr, self.end).get_mut(n) {
1541 Some(elem_ref) => unsafe {
1542 self.ptr = slice_offset!(self.ptr, (n as isize).wrapping_add(1));
1546 self.ptr = self.end;
1553 iterator!{struct IterMut -> *mut T, &'a mut T, make_ref_mut}
1555 #[stable(feature = "rust1", since = "1.0.0")]
1556 impl<'a, T> ExactSizeIterator for IterMut<'a, T> {
1557 fn is_empty(&self) -> bool {
1558 self.ptr == self.end
1562 #[unstable(feature = "fused", issue = "35602")]
1563 impl<'a, T> FusedIterator for IterMut<'a, T> {}
1565 #[unstable(feature = "trusted_len", issue = "37572")]
1566 unsafe impl<'a, T> TrustedLen for IterMut<'a, T> {}
1569 // Return the number of elements of `T` from `start` to `end`.
1570 // Return the arithmetic difference if `T` is zero size.
1572 fn ptrdistance<T>(start: *const T, end: *const T) -> usize {
1573 match start.offset_to(end) {
1574 Some(x) => x as usize,
1575 None => (end as usize).wrapping_sub(start as usize),
1579 // Extension methods for raw pointers, used by the iterators
1580 trait PointerExt : Copy {
1581 unsafe fn slice_offset(self, i: isize) -> Self;
1583 /// Increments `self` by 1, but returns the old value.
1585 unsafe fn post_inc(&mut self) -> Self {
1586 let current = *self;
1587 *self = self.slice_offset(1);
1591 /// Decrements `self` by 1, and returns the new value.
1593 unsafe fn pre_dec(&mut self) -> Self {
1594 *self = self.slice_offset(-1);
1599 impl<T> PointerExt for *const T {
1601 unsafe fn slice_offset(self, i: isize) -> Self {
1602 slice_offset!(self, i)
1606 impl<T> PointerExt for *mut T {
1608 unsafe fn slice_offset(self, i: isize) -> Self {
1609 slice_offset!(self, i)
1613 /// An internal abstraction over the splitting iterators, so that
1614 /// splitn, splitn_mut etc can be implemented once.
1616 trait SplitIter: DoubleEndedIterator {
1617 /// Marks the underlying iterator as complete, extracting the remaining
1618 /// portion of the slice.
1619 fn finish(&mut self) -> Option<Self::Item>;
1622 /// An iterator over subslices separated by elements that match a predicate
1625 /// This struct is created by the [`split`] method on [slices].
1627 /// [`split`]: ../../std/primitive.slice.html#method.split
1628 /// [slices]: ../../std/primitive.slice.html
1629 #[stable(feature = "rust1", since = "1.0.0")]
1630 pub struct Split<'a, T:'a, P> where P: FnMut(&T) -> bool {
1636 #[stable(feature = "core_impl_debug", since = "1.9.0")]
1637 impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for Split<'a, T, P> where P: FnMut(&T) -> bool {
1638 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1639 f.debug_struct("Split")
1640 .field("v", &self.v)
1641 .field("finished", &self.finished)
1646 // FIXME(#19839) Remove in favor of `#[derive(Clone)]`
1647 #[stable(feature = "rust1", since = "1.0.0")]
1648 impl<'a, T, P> Clone for Split<'a, T, P> where P: Clone + FnMut(&T) -> bool {
1649 fn clone(&self) -> Split<'a, T, P> {
1652 pred: self.pred.clone(),
1653 finished: self.finished,
1658 #[stable(feature = "rust1", since = "1.0.0")]
1659 impl<'a, T, P> Iterator for Split<'a, T, P> where P: FnMut(&T) -> bool {
1660 type Item = &'a [T];
1663 fn next(&mut self) -> Option<&'a [T]> {
1664 if self.finished { return None; }
1666 match self.v.iter().position(|x| (self.pred)(x)) {
1667 None => self.finish(),
1669 let ret = Some(&self.v[..idx]);
1670 self.v = &self.v[idx + 1..];
1677 fn size_hint(&self) -> (usize, Option<usize>) {
1681 (1, Some(self.v.len() + 1))
1686 #[stable(feature = "rust1", since = "1.0.0")]
1687 impl<'a, T, P> DoubleEndedIterator for Split<'a, T, P> where P: FnMut(&T) -> bool {
1689 fn next_back(&mut self) -> Option<&'a [T]> {
1690 if self.finished { return None; }
1692 match self.v.iter().rposition(|x| (self.pred)(x)) {
1693 None => self.finish(),
1695 let ret = Some(&self.v[idx + 1..]);
1696 self.v = &self.v[..idx];
1703 impl<'a, T, P> SplitIter for Split<'a, T, P> where P: FnMut(&T) -> bool {
1705 fn finish(&mut self) -> Option<&'a [T]> {
1706 if self.finished { None } else { self.finished = true; Some(self.v) }
1710 #[unstable(feature = "fused", issue = "35602")]
1711 impl<'a, T, P> FusedIterator for Split<'a, T, P> where P: FnMut(&T) -> bool {}
1713 /// An iterator over the subslices of the vector which are separated
1714 /// by elements that match `pred`.
1716 /// This struct is created by the [`split_mut`] method on [slices].
1718 /// [`split_mut`]: ../../std/primitive.slice.html#method.split_mut
1719 /// [slices]: ../../std/primitive.slice.html
1720 #[stable(feature = "rust1", since = "1.0.0")]
1721 pub struct SplitMut<'a, T:'a, P> where P: FnMut(&T) -> bool {
1727 #[stable(feature = "core_impl_debug", since = "1.9.0")]
1728 impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {
1729 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1730 f.debug_struct("SplitMut")
1731 .field("v", &self.v)
1732 .field("finished", &self.finished)
1737 impl<'a, T, P> SplitIter for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {
1739 fn finish(&mut self) -> Option<&'a mut [T]> {
1743 self.finished = true;
1744 Some(mem::replace(&mut self.v, &mut []))
1749 #[stable(feature = "rust1", since = "1.0.0")]
1750 impl<'a, T, P> Iterator for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {
1751 type Item = &'a mut [T];
1754 fn next(&mut self) -> Option<&'a mut [T]> {
1755 if self.finished { return None; }
1757 let idx_opt = { // work around borrowck limitations
1758 let pred = &mut self.pred;
1759 self.v.iter().position(|x| (*pred)(x))
1762 None => self.finish(),
1764 let tmp = mem::replace(&mut self.v, &mut []);
1765 let (head, tail) = tmp.split_at_mut(idx);
1766 self.v = &mut tail[1..];
1773 fn size_hint(&self) -> (usize, Option<usize>) {
1777 // if the predicate doesn't match anything, we yield one slice
1778 // if it matches every element, we yield len+1 empty slices.
1779 (1, Some(self.v.len() + 1))
1784 #[stable(feature = "rust1", since = "1.0.0")]
1785 impl<'a, T, P> DoubleEndedIterator for SplitMut<'a, T, P> where
1786 P: FnMut(&T) -> bool,
1789 fn next_back(&mut self) -> Option<&'a mut [T]> {
1790 if self.finished { return None; }
1792 let idx_opt = { // work around borrowck limitations
1793 let pred = &mut self.pred;
1794 self.v.iter().rposition(|x| (*pred)(x))
1797 None => self.finish(),
1799 let tmp = mem::replace(&mut self.v, &mut []);
1800 let (head, tail) = tmp.split_at_mut(idx);
1802 Some(&mut tail[1..])
1808 #[unstable(feature = "fused", issue = "35602")]
1809 impl<'a, T, P> FusedIterator for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {}
1811 /// An iterator over subslices separated by elements that match a predicate
1812 /// function, starting from the end of the slice.
1814 /// This struct is created by the [`rsplit`] method on [slices].
1816 /// [`rsplit`]: ../../std/primitive.slice.html#method.rsplit
1817 /// [slices]: ../../std/primitive.slice.html
1818 #[unstable(feature = "slice_rsplit", issue = "41020")]
1819 #[derive(Clone)] // Is this correct, or does it incorrectly require `T: Clone`?
1820 pub struct RSplit<'a, T:'a, P> where P: FnMut(&T) -> bool {
1821 inner: Split<'a, T, P>
1824 #[unstable(feature = "slice_rsplit", issue = "41020")]
1825 impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for RSplit<'a, T, P> where P: FnMut(&T) -> bool {
1826 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1827 f.debug_struct("RSplit")
1828 .field("v", &self.inner.v)
1829 .field("finished", &self.inner.finished)
1834 #[unstable(feature = "slice_rsplit", issue = "41020")]
1835 impl<'a, T, P> Iterator for RSplit<'a, T, P> where P: FnMut(&T) -> bool {
1836 type Item = &'a [T];
1839 fn next(&mut self) -> Option<&'a [T]> {
1840 self.inner.next_back()
1844 fn size_hint(&self) -> (usize, Option<usize>) {
1845 self.inner.size_hint()
1849 #[unstable(feature = "slice_rsplit", issue = "41020")]
1850 impl<'a, T, P> DoubleEndedIterator for RSplit<'a, T, P> where P: FnMut(&T) -> bool {
1852 fn next_back(&mut self) -> Option<&'a [T]> {
1857 #[unstable(feature = "slice_rsplit", issue = "41020")]
1858 impl<'a, T, P> SplitIter for RSplit<'a, T, P> where P: FnMut(&T) -> bool {
1860 fn finish(&mut self) -> Option<&'a [T]> {
1865 //#[unstable(feature = "fused", issue = "35602")]
1866 #[unstable(feature = "slice_rsplit", issue = "41020")]
1867 impl<'a, T, P> FusedIterator for RSplit<'a, T, P> where P: FnMut(&T) -> bool {}
1869 /// An iterator over the subslices of the vector which are separated
1870 /// by elements that match `pred`, starting from the end of the slice.
1872 /// This struct is created by the [`rsplit_mut`] method on [slices].
1874 /// [`rsplit_mut`]: ../../std/primitive.slice.html#method.rsplit_mut
1875 /// [slices]: ../../std/primitive.slice.html
1876 #[unstable(feature = "slice_rsplit", issue = "41020")]
1877 pub struct RSplitMut<'a, T:'a, P> where P: FnMut(&T) -> bool {
1878 inner: SplitMut<'a, T, P>
1881 #[unstable(feature = "slice_rsplit", issue = "41020")]
1882 impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for RSplitMut<'a, T, P> where P: FnMut(&T) -> bool {
1883 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1884 f.debug_struct("RSplitMut")
1885 .field("v", &self.inner.v)
1886 .field("finished", &self.inner.finished)
1891 #[unstable(feature = "slice_rsplit", issue = "41020")]
1892 impl<'a, T, P> SplitIter for RSplitMut<'a, T, P> where P: FnMut(&T) -> bool {
1894 fn finish(&mut self) -> Option<&'a mut [T]> {
1899 #[unstable(feature = "slice_rsplit", issue = "41020")]
1900 impl<'a, T, P> Iterator for RSplitMut<'a, T, P> where P: FnMut(&T) -> bool {
1901 type Item = &'a mut [T];
1904 fn next(&mut self) -> Option<&'a mut [T]> {
1905 self.inner.next_back()
1909 fn size_hint(&self) -> (usize, Option<usize>) {
1910 self.inner.size_hint()
1914 #[unstable(feature = "slice_rsplit", issue = "41020")]
1915 impl<'a, T, P> DoubleEndedIterator for RSplitMut<'a, T, P> where
1916 P: FnMut(&T) -> bool,
1919 fn next_back(&mut self) -> Option<&'a mut [T]> {
1924 //#[unstable(feature = "fused", issue = "35602")]
1925 #[unstable(feature = "slice_rsplit", issue = "41020")]
1926 impl<'a, T, P> FusedIterator for RSplitMut<'a, T, P> where P: FnMut(&T) -> bool {}
1928 /// An private iterator over subslices separated by elements that
1929 /// match a predicate function, splitting at most a fixed number of
1932 struct GenericSplitN<I> {
1937 impl<T, I: SplitIter<Item=T>> Iterator for GenericSplitN<I> {
1941 fn next(&mut self) -> Option<T> {
1944 1 => { self.count -= 1; self.iter.finish() }
1945 _ => { self.count -= 1; self.iter.next() }
1950 fn size_hint(&self) -> (usize, Option<usize>) {
1951 let (lower, upper_opt) = self.iter.size_hint();
1952 (lower, upper_opt.map(|upper| cmp::min(self.count, upper)))
1956 /// An iterator over subslices separated by elements that match a predicate
1957 /// function, limited to a given number of splits.
1959 /// This struct is created by the [`splitn`] method on [slices].
1961 /// [`splitn`]: ../../std/primitive.slice.html#method.splitn
1962 /// [slices]: ../../std/primitive.slice.html
1963 #[stable(feature = "rust1", since = "1.0.0")]
1964 pub struct SplitN<'a, T: 'a, P> where P: FnMut(&T) -> bool {
1965 inner: GenericSplitN<Split<'a, T, P>>
1968 #[stable(feature = "core_impl_debug", since = "1.9.0")]
1969 impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for SplitN<'a, T, P> where P: FnMut(&T) -> bool {
1970 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1971 f.debug_struct("SplitN")
1972 .field("inner", &self.inner)
1977 /// An iterator over subslices separated by elements that match a
1978 /// predicate function, limited to a given number of splits, starting
1979 /// from the end of the slice.
1981 /// This struct is created by the [`rsplitn`] method on [slices].
1983 /// [`rsplitn`]: ../../std/primitive.slice.html#method.rsplitn
1984 /// [slices]: ../../std/primitive.slice.html
1985 #[stable(feature = "rust1", since = "1.0.0")]
1986 pub struct RSplitN<'a, T: 'a, P> where P: FnMut(&T) -> bool {
1987 inner: GenericSplitN<RSplit<'a, T, P>>
1990 #[stable(feature = "core_impl_debug", since = "1.9.0")]
1991 impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for RSplitN<'a, T, P> where P: FnMut(&T) -> bool {
1992 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1993 f.debug_struct("RSplitN")
1994 .field("inner", &self.inner)
1999 /// An iterator over subslices separated by elements that match a predicate
2000 /// function, limited to a given number of splits.
2002 /// This struct is created by the [`splitn_mut`] method on [slices].
2004 /// [`splitn_mut`]: ../../std/primitive.slice.html#method.splitn_mut
2005 /// [slices]: ../../std/primitive.slice.html
2006 #[stable(feature = "rust1", since = "1.0.0")]
2007 pub struct SplitNMut<'a, T: 'a, P> where P: FnMut(&T) -> bool {
2008 inner: GenericSplitN<SplitMut<'a, T, P>>
2011 #[stable(feature = "core_impl_debug", since = "1.9.0")]
2012 impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for SplitNMut<'a, T, P> where P: FnMut(&T) -> bool {
2013 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
2014 f.debug_struct("SplitNMut")
2015 .field("inner", &self.inner)
2020 /// An iterator over subslices separated by elements that match a
2021 /// predicate function, limited to a given number of splits, starting
2022 /// from the end of the slice.
2024 /// This struct is created by the [`rsplitn_mut`] method on [slices].
2026 /// [`rsplitn_mut`]: ../../std/primitive.slice.html#method.rsplitn_mut
2027 /// [slices]: ../../std/primitive.slice.html
2028 #[stable(feature = "rust1", since = "1.0.0")]
2029 pub struct RSplitNMut<'a, T: 'a, P> where P: FnMut(&T) -> bool {
2030 inner: GenericSplitN<RSplitMut<'a, T, P>>
2033 #[stable(feature = "core_impl_debug", since = "1.9.0")]
2034 impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for RSplitNMut<'a, T, P> where P: FnMut(&T) -> bool {
2035 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
2036 f.debug_struct("RSplitNMut")
2037 .field("inner", &self.inner)
2042 macro_rules! forward_iterator {
2043 ($name:ident: $elem:ident, $iter_of:ty) => {
2044 #[stable(feature = "rust1", since = "1.0.0")]
2045 impl<'a, $elem, P> Iterator for $name<'a, $elem, P> where
2046 P: FnMut(&T) -> bool
2048 type Item = $iter_of;
2051 fn next(&mut self) -> Option<$iter_of> {
2056 fn size_hint(&self) -> (usize, Option<usize>) {
2057 self.inner.size_hint()
2061 #[unstable(feature = "fused", issue = "35602")]
2062 impl<'a, $elem, P> FusedIterator for $name<'a, $elem, P>
2063 where P: FnMut(&T) -> bool {}
2067 forward_iterator! { SplitN: T, &'a [T] }
2068 forward_iterator! { RSplitN: T, &'a [T] }
2069 forward_iterator! { SplitNMut: T, &'a mut [T] }
2070 forward_iterator! { RSplitNMut: T, &'a mut [T] }
2072 /// An iterator over overlapping subslices of length `size`.
2074 /// This struct is created by the [`windows`] method on [slices].
2076 /// [`windows`]: ../../std/primitive.slice.html#method.windows
2077 /// [slices]: ../../std/primitive.slice.html
2079 #[stable(feature = "rust1", since = "1.0.0")]
2080 pub struct Windows<'a, T:'a> {
2085 // FIXME(#19839) Remove in favor of `#[derive(Clone)]`
2086 #[stable(feature = "rust1", since = "1.0.0")]
2087 impl<'a, T> Clone for Windows<'a, T> {
2088 fn clone(&self) -> Windows<'a, T> {
2096 #[stable(feature = "rust1", since = "1.0.0")]
2097 impl<'a, T> Iterator for Windows<'a, T> {
2098 type Item = &'a [T];
2101 fn next(&mut self) -> Option<&'a [T]> {
2102 if self.size > self.v.len() {
2105 let ret = Some(&self.v[..self.size]);
2106 self.v = &self.v[1..];
2112 fn size_hint(&self) -> (usize, Option<usize>) {
2113 if self.size > self.v.len() {
2116 let size = self.v.len() - self.size + 1;
2122 fn count(self) -> usize {
2127 fn nth(&mut self, n: usize) -> Option<Self::Item> {
2128 let (end, overflow) = self.size.overflowing_add(n);
2129 if end > self.v.len() || overflow {
2133 let nth = &self.v[n..end];
2134 self.v = &self.v[n+1..];
2140 fn last(self) -> Option<Self::Item> {
2141 if self.size > self.v.len() {
2144 let start = self.v.len() - self.size;
2145 Some(&self.v[start..])
2150 #[stable(feature = "rust1", since = "1.0.0")]
2151 impl<'a, T> DoubleEndedIterator for Windows<'a, T> {
2153 fn next_back(&mut self) -> Option<&'a [T]> {
2154 if self.size > self.v.len() {
2157 let ret = Some(&self.v[self.v.len()-self.size..]);
2158 self.v = &self.v[..self.v.len()-1];
2164 #[stable(feature = "rust1", since = "1.0.0")]
2165 impl<'a, T> ExactSizeIterator for Windows<'a, T> {}
2167 #[unstable(feature = "fused", issue = "35602")]
2168 impl<'a, T> FusedIterator for Windows<'a, T> {}
2170 /// An iterator over a slice in (non-overlapping) chunks (`size` elements at a
2173 /// When the slice len is not evenly divided by the chunk size, the last slice
2174 /// of the iteration will be the remainder.
2176 /// This struct is created by the [`chunks`] method on [slices].
2178 /// [`chunks`]: ../../std/primitive.slice.html#method.chunks
2179 /// [slices]: ../../std/primitive.slice.html
2181 #[stable(feature = "rust1", since = "1.0.0")]
2182 pub struct Chunks<'a, T:'a> {
2187 // FIXME(#19839) Remove in favor of `#[derive(Clone)]`
2188 #[stable(feature = "rust1", since = "1.0.0")]
2189 impl<'a, T> Clone for Chunks<'a, T> {
2190 fn clone(&self) -> Chunks<'a, T> {
2198 #[stable(feature = "rust1", since = "1.0.0")]
2199 impl<'a, T> Iterator for Chunks<'a, T> {
2200 type Item = &'a [T];
2203 fn next(&mut self) -> Option<&'a [T]> {
2204 if self.v.is_empty() {
2207 let chunksz = cmp::min(self.v.len(), self.size);
2208 let (fst, snd) = self.v.split_at(chunksz);
2215 fn size_hint(&self) -> (usize, Option<usize>) {
2216 if self.v.is_empty() {
2219 let n = self.v.len() / self.size;
2220 let rem = self.v.len() % self.size;
2221 let n = if rem > 0 { n+1 } else { n };
2227 fn count(self) -> usize {
2232 fn nth(&mut self, n: usize) -> Option<Self::Item> {
2233 let (start, overflow) = n.overflowing_mul(self.size);
2234 if start >= self.v.len() || overflow {
2238 let end = match start.checked_add(self.size) {
2239 Some(sum) => cmp::min(self.v.len(), sum),
2240 None => self.v.len(),
2242 let nth = &self.v[start..end];
2243 self.v = &self.v[end..];
2249 fn last(self) -> Option<Self::Item> {
2250 if self.v.is_empty() {
2253 let start = (self.v.len() - 1) / self.size * self.size;
2254 Some(&self.v[start..])
2259 #[stable(feature = "rust1", since = "1.0.0")]
2260 impl<'a, T> DoubleEndedIterator for Chunks<'a, T> {
2262 fn next_back(&mut self) -> Option<&'a [T]> {
2263 if self.v.is_empty() {
2266 let remainder = self.v.len() % self.size;
2267 let chunksz = if remainder != 0 { remainder } else { self.size };
2268 let (fst, snd) = self.v.split_at(self.v.len() - chunksz);
2275 #[stable(feature = "rust1", since = "1.0.0")]
2276 impl<'a, T> ExactSizeIterator for Chunks<'a, T> {}
2278 #[unstable(feature = "fused", issue = "35602")]
2279 impl<'a, T> FusedIterator for Chunks<'a, T> {}
2281 /// An iterator over a slice in (non-overlapping) mutable chunks (`size`
2282 /// elements at a time). When the slice len is not evenly divided by the chunk
2283 /// size, the last slice of the iteration will be the remainder.
2285 /// This struct is created by the [`chunks_mut`] method on [slices].
2287 /// [`chunks_mut`]: ../../std/primitive.slice.html#method.chunks_mut
2288 /// [slices]: ../../std/primitive.slice.html
2290 #[stable(feature = "rust1", since = "1.0.0")]
2291 pub struct ChunksMut<'a, T:'a> {
2296 #[stable(feature = "rust1", since = "1.0.0")]
2297 impl<'a, T> Iterator for ChunksMut<'a, T> {
2298 type Item = &'a mut [T];
2301 fn next(&mut self) -> Option<&'a mut [T]> {
2302 if self.v.is_empty() {
2305 let sz = cmp::min(self.v.len(), self.chunk_size);
2306 let tmp = mem::replace(&mut self.v, &mut []);
2307 let (head, tail) = tmp.split_at_mut(sz);
2314 fn size_hint(&self) -> (usize, Option<usize>) {
2315 if self.v.is_empty() {
2318 let n = self.v.len() / self.chunk_size;
2319 let rem = self.v.len() % self.chunk_size;
2320 let n = if rem > 0 { n + 1 } else { n };
2326 fn count(self) -> usize {
2331 fn nth(&mut self, n: usize) -> Option<&'a mut [T]> {
2332 let (start, overflow) = n.overflowing_mul(self.chunk_size);
2333 if start >= self.v.len() || overflow {
2337 let end = match start.checked_add(self.chunk_size) {
2338 Some(sum) => cmp::min(self.v.len(), sum),
2339 None => self.v.len(),
2341 let tmp = mem::replace(&mut self.v, &mut []);
2342 let (head, tail) = tmp.split_at_mut(end);
2343 let (_, nth) = head.split_at_mut(start);
2350 fn last(self) -> Option<Self::Item> {
2351 if self.v.is_empty() {
2354 let start = (self.v.len() - 1) / self.chunk_size * self.chunk_size;
2355 Some(&mut self.v[start..])
2360 #[stable(feature = "rust1", since = "1.0.0")]
2361 impl<'a, T> DoubleEndedIterator for ChunksMut<'a, T> {
2363 fn next_back(&mut self) -> Option<&'a mut [T]> {
2364 if self.v.is_empty() {
2367 let remainder = self.v.len() % self.chunk_size;
2368 let sz = if remainder != 0 { remainder } else { self.chunk_size };
2369 let tmp = mem::replace(&mut self.v, &mut []);
2370 let tmp_len = tmp.len();
2371 let (head, tail) = tmp.split_at_mut(tmp_len - sz);
2378 #[stable(feature = "rust1", since = "1.0.0")]
2379 impl<'a, T> ExactSizeIterator for ChunksMut<'a, T> {}
2381 #[unstable(feature = "fused", issue = "35602")]
2382 impl<'a, T> FusedIterator for ChunksMut<'a, T> {}
2388 /// Forms a slice from a pointer and a length.
2390 /// The `len` argument is the number of **elements**, not the number of bytes.
2394 /// This function is unsafe as there is no guarantee that the given pointer is
2395 /// valid for `len` elements, nor whether the lifetime inferred is a suitable
2396 /// lifetime for the returned slice.
2398 /// `p` must be non-null, even for zero-length slices, because non-zero bits
2399 /// are required to distinguish between a zero-length slice within `Some()`
2400 /// from `None`. `p` can be a bogus non-dereferencable pointer, such as `0x1`,
2401 /// for zero-length slices, though.
2405 /// The lifetime for the returned slice is inferred from its usage. To
2406 /// prevent accidental misuse, it's suggested to tie the lifetime to whichever
2407 /// source lifetime is safe in the context, such as by providing a helper
2408 /// function taking the lifetime of a host value for the slice, or by explicit
2416 /// // manifest a slice out of thin air!
2417 /// let ptr = 0x1234 as *const usize;
2420 /// let slice = slice::from_raw_parts(ptr, amt);
2424 #[stable(feature = "rust1", since = "1.0.0")]
2425 pub unsafe fn from_raw_parts<'a, T>(p: *const T, len: usize) -> &'a [T] {
2426 mem::transmute(Repr { data: p, len: len })
2429 /// Performs the same functionality as `from_raw_parts`, except that a mutable
2430 /// slice is returned.
2432 /// This function is unsafe for the same reasons as `from_raw_parts`, as well
2433 /// as not being able to provide a non-aliasing guarantee of the returned
2434 /// mutable slice. `p` must be non-null even for zero-length slices as with
2435 /// `from_raw_parts`.
2437 #[stable(feature = "rust1", since = "1.0.0")]
2438 pub unsafe fn from_raw_parts_mut<'a, T>(p: *mut T, len: usize) -> &'a mut [T] {
2439 mem::transmute(Repr { data: p, len: len })
2442 // This function is public only because there is no other way to unit test heapsort.
2443 #[unstable(feature = "sort_internals", reason = "internal to sort module", issue = "0")]
2445 pub fn heapsort<T, F>(v: &mut [T], mut is_less: F)
2446 where F: FnMut(&T, &T) -> bool
2448 sort::heapsort(v, &mut is_less);
2452 // Comparison traits
2456 /// Calls implementation provided memcmp.
2458 /// Interprets the data as u8.
2460 /// Returns 0 for equal, < 0 for less than and > 0 for greater
2462 // FIXME(#32610): Return type should be c_int
2463 fn memcmp(s1: *const u8, s2: *const u8, n: usize) -> i32;
2466 #[stable(feature = "rust1", since = "1.0.0")]
2467 impl<A, B> PartialEq<[B]> for [A] where A: PartialEq<B> {
2468 fn eq(&self, other: &[B]) -> bool {
2469 SlicePartialEq::equal(self, other)
2472 fn ne(&self, other: &[B]) -> bool {
2473 SlicePartialEq::not_equal(self, other)
2477 #[stable(feature = "rust1", since = "1.0.0")]
2478 impl<T: Eq> Eq for [T] {}
2480 /// Implements comparison of vectors lexicographically.
2481 #[stable(feature = "rust1", since = "1.0.0")]
2482 impl<T: Ord> Ord for [T] {
2483 fn cmp(&self, other: &[T]) -> Ordering {
2484 SliceOrd::compare(self, other)
2488 /// Implements comparison of vectors lexicographically.
2489 #[stable(feature = "rust1", since = "1.0.0")]
2490 impl<T: PartialOrd> PartialOrd for [T] {
2491 fn partial_cmp(&self, other: &[T]) -> Option<Ordering> {
2492 SlicePartialOrd::partial_compare(self, other)
2497 // intermediate trait for specialization of slice's PartialEq
2498 trait SlicePartialEq<B> {
2499 fn equal(&self, other: &[B]) -> bool;
2501 fn not_equal(&self, other: &[B]) -> bool { !self.equal(other) }
2504 // Generic slice equality
2505 impl<A, B> SlicePartialEq<B> for [A]
2506 where A: PartialEq<B>
2508 default fn equal(&self, other: &[B]) -> bool {
2509 if self.len() != other.len() {
2513 for i in 0..self.len() {
2514 if !self[i].eq(&other[i]) {
2523 // Use memcmp for bytewise equality when the types allow
2524 impl<A> SlicePartialEq<A> for [A]
2525 where A: PartialEq<A> + BytewiseEquality
2527 fn equal(&self, other: &[A]) -> bool {
2528 if self.len() != other.len() {
2531 if self.as_ptr() == other.as_ptr() {
2535 let size = mem::size_of_val(self);
2536 memcmp(self.as_ptr() as *const u8,
2537 other.as_ptr() as *const u8, size) == 0
2543 // intermediate trait for specialization of slice's PartialOrd
2544 trait SlicePartialOrd<B> {
2545 fn partial_compare(&self, other: &[B]) -> Option<Ordering>;
2548 impl<A> SlicePartialOrd<A> for [A]
2551 default fn partial_compare(&self, other: &[A]) -> Option<Ordering> {
2552 let l = cmp::min(self.len(), other.len());
2554 // Slice to the loop iteration range to enable bound check
2555 // elimination in the compiler
2556 let lhs = &self[..l];
2557 let rhs = &other[..l];
2560 match lhs[i].partial_cmp(&rhs[i]) {
2561 Some(Ordering::Equal) => (),
2562 non_eq => return non_eq,
2566 self.len().partial_cmp(&other.len())
2570 impl<A> SlicePartialOrd<A> for [A]
2573 default fn partial_compare(&self, other: &[A]) -> Option<Ordering> {
2574 Some(SliceOrd::compare(self, other))
2579 // intermediate trait for specialization of slice's Ord
2581 fn compare(&self, other: &[B]) -> Ordering;
2584 impl<A> SliceOrd<A> for [A]
2587 default fn compare(&self, other: &[A]) -> Ordering {
2588 let l = cmp::min(self.len(), other.len());
2590 // Slice to the loop iteration range to enable bound check
2591 // elimination in the compiler
2592 let lhs = &self[..l];
2593 let rhs = &other[..l];
2596 match lhs[i].cmp(&rhs[i]) {
2597 Ordering::Equal => (),
2598 non_eq => return non_eq,
2602 self.len().cmp(&other.len())
2606 // memcmp compares a sequence of unsigned bytes lexicographically.
2607 // this matches the order we want for [u8], but no others (not even [i8]).
2608 impl SliceOrd<u8> for [u8] {
2610 fn compare(&self, other: &[u8]) -> Ordering {
2611 let order = unsafe {
2612 memcmp(self.as_ptr(), other.as_ptr(),
2613 cmp::min(self.len(), other.len()))
2616 self.len().cmp(&other.len())
2617 } else if order < 0 {
2626 /// Trait implemented for types that can be compared for equality using
2627 /// their bytewise representation
2628 trait BytewiseEquality { }
2630 macro_rules! impl_marker_for {
2631 ($traitname:ident, $($ty:ty)*) => {
2633 impl $traitname for $ty { }
2638 impl_marker_for!(BytewiseEquality,
2639 u8 i8 u16 i16 u32 i32 u64 i64 usize isize char bool);
2642 unsafe impl<'a, T> TrustedRandomAccess for Iter<'a, T> {
2643 unsafe fn get_unchecked(&mut self, i: usize) -> &'a T {
2644 &*self.ptr.offset(i as isize)
2646 fn may_have_side_effect() -> bool { false }
2650 unsafe impl<'a, T> TrustedRandomAccess for IterMut<'a, T> {
2651 unsafe fn get_unchecked(&mut self, i: usize) -> &'a mut T {
2652 &mut *self.ptr.offset(i as isize)
2654 fn may_have_side_effect() -> bool { false }