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 = "123456789")]
207 fn rotate(&mut self, mid: usize) -> 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 #[unstable(feature = "sort_unstable", issue = "40585")]
216 fn sort_unstable(&mut self)
217 where Self::Item: Ord;
219 #[unstable(feature = "sort_unstable", issue = "40585")]
220 fn sort_unstable_by<F>(&mut self, compare: F)
221 where F: FnMut(&Self::Item, &Self::Item) -> Ordering;
223 #[unstable(feature = "sort_unstable", issue = "40585")]
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) -> 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);
655 fn clone_from_slice(&mut self, src: &[T]) where T: Clone {
656 assert!(self.len() == src.len(),
657 "destination and source slices have different lengths");
658 // NOTE: We need to explicitly slice them to the same length
659 // for bounds checking to be elided, and the optimizer will
660 // generate memcpy for simple cases (for example T = u8).
661 let len = self.len();
662 let src = &src[..len];
664 self[i].clone_from(&src[i]);
669 fn copy_from_slice(&mut self, src: &[T]) where T: Copy {
670 assert!(self.len() == src.len(),
671 "destination and source slices have different lengths");
673 ptr::copy_nonoverlapping(
674 src.as_ptr(), self.as_mut_ptr(), self.len());
679 fn binary_search_by_key<'a, B, F, Q: ?Sized>(&'a self, b: &Q, mut f: F) -> Result<usize, usize>
680 where F: FnMut(&'a Self::Item) -> B,
684 self.binary_search_by(|k| f(k).borrow().cmp(b))
688 fn sort_unstable(&mut self)
689 where Self::Item: Ord
691 sort::quicksort(self, |a, b| a.lt(b));
695 fn sort_unstable_by<F>(&mut self, mut compare: F)
696 where F: FnMut(&Self::Item, &Self::Item) -> Ordering
698 sort::quicksort(self, |a, b| compare(a, b) == Ordering::Less);
702 fn sort_unstable_by_key<B, F>(&mut self, mut f: F)
703 where F: FnMut(&Self::Item) -> B,
706 sort::quicksort(self, |a, b| f(a).lt(&f(b)));
710 #[stable(feature = "rust1", since = "1.0.0")]
711 #[rustc_on_unimplemented = "slice indices are of type `usize` or ranges of `usize`"]
712 impl<T, I> ops::Index<I> for [T]
713 where I: SliceIndex<[T]>
715 type Output = I::Output;
718 fn index(&self, index: I) -> &I::Output {
723 #[stable(feature = "rust1", since = "1.0.0")]
724 #[rustc_on_unimplemented = "slice indices are of type `usize` or ranges of `usize`"]
725 impl<T, I> ops::IndexMut<I> for [T]
726 where I: SliceIndex<[T]>
729 fn index_mut(&mut self, index: I) -> &mut I::Output {
730 index.index_mut(self)
736 fn slice_index_len_fail(index: usize, len: usize) -> ! {
737 panic!("index {} out of range for slice of length {}", index, len);
742 fn slice_index_order_fail(index: usize, end: usize) -> ! {
743 panic!("slice index starts at {} but ends at {}", index, end);
746 /// A helper trait used for indexing operations.
747 #[unstable(feature = "slice_get_slice", issue = "35729")]
748 #[rustc_on_unimplemented = "slice indices are of type `usize` or ranges of `usize`"]
749 pub trait SliceIndex<T: ?Sized> {
750 /// The output type returned by methods.
753 /// Returns a shared reference to the output at this location, if in
755 fn get(self, slice: &T) -> Option<&Self::Output>;
757 /// Returns a mutable reference to the output at this location, if in
759 fn get_mut(self, slice: &mut T) -> Option<&mut Self::Output>;
761 /// Returns a shared reference to the output at this location, without
762 /// performing any bounds checking.
763 unsafe fn get_unchecked(self, slice: &T) -> &Self::Output;
765 /// Returns a mutable reference to the output at this location, without
766 /// performing any bounds checking.
767 unsafe fn get_unchecked_mut(self, slice: &mut T) -> &mut Self::Output;
769 /// Returns a shared reference to the output at this location, panicking
770 /// if out of bounds.
771 fn index(self, slice: &T) -> &Self::Output;
773 /// Returns a mutable reference to the output at this location, panicking
774 /// if out of bounds.
775 fn index_mut(self, slice: &mut T) -> &mut Self::Output;
778 #[stable(feature = "slice-get-slice-impls", since = "1.15.0")]
779 impl<T> SliceIndex<[T]> for usize {
783 fn get(self, slice: &[T]) -> Option<&T> {
784 if self < slice.len() {
786 Some(self.get_unchecked(slice))
794 fn get_mut(self, slice: &mut [T]) -> Option<&mut T> {
795 if self < slice.len() {
797 Some(self.get_unchecked_mut(slice))
805 unsafe fn get_unchecked(self, slice: &[T]) -> &T {
806 &*slice.as_ptr().offset(self as isize)
810 unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut T {
811 &mut *slice.as_mut_ptr().offset(self as isize)
815 fn index(self, slice: &[T]) -> &T {
816 // NB: use intrinsic indexing
821 fn index_mut(self, slice: &mut [T]) -> &mut T {
822 // NB: use intrinsic indexing
827 #[stable(feature = "slice-get-slice-impls", since = "1.15.0")]
828 impl<T> SliceIndex<[T]> for ops::Range<usize> {
832 fn get(self, slice: &[T]) -> Option<&[T]> {
833 if self.start > self.end || self.end > slice.len() {
837 Some(self.get_unchecked(slice))
843 fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
844 if self.start > self.end || self.end > slice.len() {
848 Some(self.get_unchecked_mut(slice))
854 unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
855 from_raw_parts(slice.as_ptr().offset(self.start as isize), self.end - self.start)
859 unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
860 from_raw_parts_mut(slice.as_mut_ptr().offset(self.start as isize), self.end - self.start)
864 fn index(self, slice: &[T]) -> &[T] {
865 if self.start > self.end {
866 slice_index_order_fail(self.start, self.end);
867 } else if self.end > slice.len() {
868 slice_index_len_fail(self.end, slice.len());
871 self.get_unchecked(slice)
876 fn index_mut(self, slice: &mut [T]) -> &mut [T] {
877 if self.start > self.end {
878 slice_index_order_fail(self.start, self.end);
879 } else if self.end > slice.len() {
880 slice_index_len_fail(self.end, slice.len());
883 self.get_unchecked_mut(slice)
888 #[stable(feature = "slice-get-slice-impls", since = "1.15.0")]
889 impl<T> SliceIndex<[T]> for ops::RangeTo<usize> {
893 fn get(self, slice: &[T]) -> Option<&[T]> {
894 (0..self.end).get(slice)
898 fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
899 (0..self.end).get_mut(slice)
903 unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
904 (0..self.end).get_unchecked(slice)
908 unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
909 (0..self.end).get_unchecked_mut(slice)
913 fn index(self, slice: &[T]) -> &[T] {
914 (0..self.end).index(slice)
918 fn index_mut(self, slice: &mut [T]) -> &mut [T] {
919 (0..self.end).index_mut(slice)
923 #[stable(feature = "slice-get-slice-impls", since = "1.15.0")]
924 impl<T> SliceIndex<[T]> for ops::RangeFrom<usize> {
928 fn get(self, slice: &[T]) -> Option<&[T]> {
929 (self.start..slice.len()).get(slice)
933 fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
934 (self.start..slice.len()).get_mut(slice)
938 unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
939 (self.start..slice.len()).get_unchecked(slice)
943 unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
944 (self.start..slice.len()).get_unchecked_mut(slice)
948 fn index(self, slice: &[T]) -> &[T] {
949 (self.start..slice.len()).index(slice)
953 fn index_mut(self, slice: &mut [T]) -> &mut [T] {
954 (self.start..slice.len()).index_mut(slice)
958 #[stable(feature = "slice-get-slice-impls", since = "1.15.0")]
959 impl<T> SliceIndex<[T]> for ops::RangeFull {
963 fn get(self, slice: &[T]) -> Option<&[T]> {
968 fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
973 unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
978 unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
983 fn index(self, slice: &[T]) -> &[T] {
988 fn index_mut(self, slice: &mut [T]) -> &mut [T] {
994 #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
995 impl<T> SliceIndex<[T]> for ops::RangeInclusive<usize> {
999 fn get(self, slice: &[T]) -> Option<&[T]> {
1001 ops::RangeInclusive::Empty { .. } => Some(&[]),
1002 ops::RangeInclusive::NonEmpty { end, .. } if end == usize::max_value() => None,
1003 ops::RangeInclusive::NonEmpty { start, end } => (start..end + 1).get(slice),
1008 fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
1010 ops::RangeInclusive::Empty { .. } => Some(&mut []),
1011 ops::RangeInclusive::NonEmpty { end, .. } if end == usize::max_value() => None,
1012 ops::RangeInclusive::NonEmpty { start, end } => (start..end + 1).get_mut(slice),
1017 unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
1019 ops::RangeInclusive::Empty { .. } => &[],
1020 ops::RangeInclusive::NonEmpty { start, end } => (start..end + 1).get_unchecked(slice),
1025 unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
1027 ops::RangeInclusive::Empty { .. } => &mut [],
1028 ops::RangeInclusive::NonEmpty { start, end } => {
1029 (start..end + 1).get_unchecked_mut(slice)
1035 fn index(self, slice: &[T]) -> &[T] {
1037 ops::RangeInclusive::Empty { .. } => &[],
1038 ops::RangeInclusive::NonEmpty { end, .. } if end == usize::max_value() => {
1039 panic!("attempted to index slice up to maximum usize");
1041 ops::RangeInclusive::NonEmpty { start, end } => (start..end + 1).index(slice),
1046 fn index_mut(self, slice: &mut [T]) -> &mut [T] {
1048 ops::RangeInclusive::Empty { .. } => &mut [],
1049 ops::RangeInclusive::NonEmpty { end, .. } if end == usize::max_value() => {
1050 panic!("attempted to index slice up to maximum usize");
1052 ops::RangeInclusive::NonEmpty { start, end } => (start..end + 1).index_mut(slice),
1057 #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
1058 impl<T> SliceIndex<[T]> for ops::RangeToInclusive<usize> {
1062 fn get(self, slice: &[T]) -> Option<&[T]> {
1063 (0...self.end).get(slice)
1067 fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
1068 (0...self.end).get_mut(slice)
1072 unsafe fn get_unchecked(self, slice: &[T]) -> &[T] {
1073 (0...self.end).get_unchecked(slice)
1077 unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T] {
1078 (0...self.end).get_unchecked_mut(slice)
1082 fn index(self, slice: &[T]) -> &[T] {
1083 (0...self.end).index(slice)
1087 fn index_mut(self, slice: &mut [T]) -> &mut [T] {
1088 (0...self.end).index_mut(slice)
1092 ////////////////////////////////////////////////////////////////////////////////
1094 ////////////////////////////////////////////////////////////////////////////////
1096 #[stable(feature = "rust1", since = "1.0.0")]
1097 impl<'a, T> Default for &'a [T] {
1098 /// Creates an empty slice.
1099 fn default() -> &'a [T] { &[] }
1102 #[stable(feature = "mut_slice_default", since = "1.5.0")]
1103 impl<'a, T> Default for &'a mut [T] {
1104 /// Creates a mutable empty slice.
1105 fn default() -> &'a mut [T] { &mut [] }
1112 #[stable(feature = "rust1", since = "1.0.0")]
1113 impl<'a, T> IntoIterator for &'a [T] {
1115 type IntoIter = Iter<'a, T>;
1117 fn into_iter(self) -> Iter<'a, T> {
1122 #[stable(feature = "rust1", since = "1.0.0")]
1123 impl<'a, T> IntoIterator for &'a mut [T] {
1124 type Item = &'a mut T;
1125 type IntoIter = IterMut<'a, T>;
1127 fn into_iter(self) -> IterMut<'a, T> {
1133 fn size_from_ptr<T>(_: *const T) -> usize {
1137 // The shared definition of the `Iter` and `IterMut` iterators
1138 macro_rules! iterator {
1139 (struct $name:ident -> $ptr:ty, $elem:ty, $mkref:ident) => {
1140 #[stable(feature = "rust1", since = "1.0.0")]
1141 impl<'a, T> Iterator for $name<'a, T> {
1145 fn next(&mut self) -> Option<$elem> {
1146 // could be implemented with slices, but this avoids bounds checks
1148 if mem::size_of::<T>() != 0 {
1149 assume(!self.ptr.is_null());
1150 assume(!self.end.is_null());
1152 if self.ptr == self.end {
1155 Some($mkref!(self.ptr.post_inc()))
1161 fn size_hint(&self) -> (usize, Option<usize>) {
1162 let exact = ptrdistance(self.ptr, self.end);
1163 (exact, Some(exact))
1167 fn count(self) -> usize {
1172 fn nth(&mut self, n: usize) -> Option<$elem> {
1173 // Call helper method. Can't put the definition here because mut versus const.
1178 fn last(mut self) -> Option<$elem> {
1182 fn all<F>(&mut self, mut predicate: F) -> bool
1183 where F: FnMut(Self::Item) -> bool,
1185 self.search_while(true, move |elt| {
1187 SearchWhile::Continue
1189 SearchWhile::Done(false)
1194 fn any<F>(&mut self, mut predicate: F) -> bool
1195 where F: FnMut(Self::Item) -> bool,
1197 !self.all(move |elt| !predicate(elt))
1200 fn find<F>(&mut self, mut predicate: F) -> Option<Self::Item>
1201 where F: FnMut(&Self::Item) -> bool,
1203 self.search_while(None, move |elt| {
1204 if predicate(&elt) {
1205 SearchWhile::Done(Some(elt))
1207 SearchWhile::Continue
1212 fn position<F>(&mut self, mut predicate: F) -> Option<usize>
1213 where F: FnMut(Self::Item) -> bool,
1216 self.search_while(None, move |elt| {
1218 SearchWhile::Done(Some(index))
1221 SearchWhile::Continue
1226 fn rposition<F>(&mut self, mut predicate: F) -> Option<usize>
1227 where F: FnMut(Self::Item) -> bool,
1229 let mut index = self.len();
1230 self.rsearch_while(None, move |elt| {
1233 SearchWhile::Done(Some(index))
1235 SearchWhile::Continue
1241 #[stable(feature = "rust1", since = "1.0.0")]
1242 impl<'a, T> DoubleEndedIterator for $name<'a, T> {
1244 fn next_back(&mut self) -> Option<$elem> {
1245 // could be implemented with slices, but this avoids bounds checks
1247 if mem::size_of::<T>() != 0 {
1248 assume(!self.ptr.is_null());
1249 assume(!self.end.is_null());
1251 if self.end == self.ptr {
1254 Some($mkref!(self.end.pre_dec()))
1259 fn rfind<F>(&mut self, mut predicate: F) -> Option<Self::Item>
1260 where F: FnMut(&Self::Item) -> bool,
1262 self.rsearch_while(None, move |elt| {
1263 if predicate(&elt) {
1264 SearchWhile::Done(Some(elt))
1266 SearchWhile::Continue
1273 // search_while is a generalization of the internal iteration methods.
1274 impl<'a, T> $name<'a, T> {
1275 // search through the iterator's element using the closure `g`.
1276 // if no element was found, return `default`.
1277 fn search_while<Acc, G>(&mut self, default: Acc, mut g: G) -> Acc
1279 G: FnMut($elem) -> SearchWhile<Acc>
1281 // manual unrolling is needed when there are conditional exits from the loop
1283 while ptrdistance(self.ptr, self.end) >= 4 {
1284 search_while!(g($mkref!(self.ptr.post_inc())));
1285 search_while!(g($mkref!(self.ptr.post_inc())));
1286 search_while!(g($mkref!(self.ptr.post_inc())));
1287 search_while!(g($mkref!(self.ptr.post_inc())));
1289 while self.ptr != self.end {
1290 search_while!(g($mkref!(self.ptr.post_inc())));
1296 fn rsearch_while<Acc, G>(&mut self, default: Acc, mut g: G) -> Acc
1298 G: FnMut($elem) -> SearchWhile<Acc>
1301 while ptrdistance(self.ptr, self.end) >= 4 {
1302 search_while!(g($mkref!(self.end.pre_dec())));
1303 search_while!(g($mkref!(self.end.pre_dec())));
1304 search_while!(g($mkref!(self.end.pre_dec())));
1305 search_while!(g($mkref!(self.end.pre_dec())));
1307 while self.ptr != self.end {
1308 search_while!(g($mkref!(self.end.pre_dec())));
1317 macro_rules! make_slice {
1318 ($start: expr, $end: expr) => {{
1320 let diff = ($end as usize).wrapping_sub(start as usize);
1321 if size_from_ptr(start) == 0 {
1322 // use a non-null pointer value
1323 unsafe { from_raw_parts(1 as *const _, diff) }
1325 let len = diff / size_from_ptr(start);
1326 unsafe { from_raw_parts(start, len) }
1331 macro_rules! make_mut_slice {
1332 ($start: expr, $end: expr) => {{
1334 let diff = ($end as usize).wrapping_sub(start as usize);
1335 if size_from_ptr(start) == 0 {
1336 // use a non-null pointer value
1337 unsafe { from_raw_parts_mut(1 as *mut _, diff) }
1339 let len = diff / size_from_ptr(start);
1340 unsafe { from_raw_parts_mut(start, len) }
1345 // An enum used for controlling the execution of `.search_while()`.
1346 enum SearchWhile<T> {
1347 // Continue searching
1349 // Fold is complete and will return this value
1353 // helper macro for search while's control flow
1354 macro_rules! search_while {
1357 SearchWhile::Continue => { }
1358 SearchWhile::Done(done) => return done,
1363 /// Immutable slice iterator
1365 /// This struct is created by the [`iter`] method on [slices].
1372 /// // First, we declare a type which has `iter` method to get the `Iter` struct (&[usize here]):
1373 /// let slice = &[1, 2, 3];
1375 /// // Then, we iterate over it:
1376 /// for element in slice.iter() {
1377 /// println!("{}", element);
1381 /// [`iter`]: ../../std/primitive.slice.html#method.iter
1382 /// [slices]: ../../std/primitive.slice.html
1383 #[stable(feature = "rust1", since = "1.0.0")]
1384 pub struct Iter<'a, T: 'a> {
1387 _marker: marker::PhantomData<&'a T>,
1390 #[stable(feature = "core_impl_debug", since = "1.9.0")]
1391 impl<'a, T: 'a + fmt::Debug> fmt::Debug for Iter<'a, T> {
1392 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1393 f.debug_tuple("Iter")
1394 .field(&self.as_slice())
1399 #[stable(feature = "rust1", since = "1.0.0")]
1400 unsafe impl<'a, T: Sync> Sync for Iter<'a, T> {}
1401 #[stable(feature = "rust1", since = "1.0.0")]
1402 unsafe impl<'a, T: Sync> Send for Iter<'a, T> {}
1404 impl<'a, T> Iter<'a, T> {
1405 /// View the underlying data as a subslice of the original data.
1407 /// This has the same lifetime as the original slice, and so the
1408 /// iterator can continue to be used while this exists.
1415 /// // First, we declare a type which has the `iter` method to get the `Iter`
1416 /// // struct (&[usize here]):
1417 /// let slice = &[1, 2, 3];
1419 /// // Then, we get the iterator:
1420 /// let mut iter = slice.iter();
1421 /// // So if we print what `as_slice` method returns here, we have "[1, 2, 3]":
1422 /// println!("{:?}", iter.as_slice());
1424 /// // Next, we move to the second element of the slice:
1426 /// // Now `as_slice` returns "[2, 3]":
1427 /// println!("{:?}", iter.as_slice());
1429 #[stable(feature = "iter_to_slice", since = "1.4.0")]
1430 pub fn as_slice(&self) -> &'a [T] {
1431 make_slice!(self.ptr, self.end)
1434 // Helper function for Iter::nth
1435 fn iter_nth(&mut self, n: usize) -> Option<&'a T> {
1436 match self.as_slice().get(n) {
1437 Some(elem_ref) => unsafe {
1438 self.ptr = slice_offset!(self.ptr, (n as isize).wrapping_add(1));
1442 self.ptr = self.end;
1449 iterator!{struct Iter -> *const T, &'a T, make_ref}
1451 #[stable(feature = "rust1", since = "1.0.0")]
1452 impl<'a, T> ExactSizeIterator for Iter<'a, T> {
1453 fn is_empty(&self) -> bool {
1454 self.ptr == self.end
1458 #[unstable(feature = "fused", issue = "35602")]
1459 impl<'a, T> FusedIterator for Iter<'a, T> {}
1461 #[unstable(feature = "trusted_len", issue = "37572")]
1462 unsafe impl<'a, T> TrustedLen for Iter<'a, T> {}
1464 #[stable(feature = "rust1", since = "1.0.0")]
1465 impl<'a, T> Clone for Iter<'a, T> {
1466 fn clone(&self) -> Iter<'a, T> { Iter { ptr: self.ptr, end: self.end, _marker: self._marker } }
1469 #[stable(feature = "slice_iter_as_ref", since = "1.12.0")]
1470 impl<'a, T> AsRef<[T]> for Iter<'a, T> {
1471 fn as_ref(&self) -> &[T] {
1476 /// Mutable slice iterator.
1478 /// This struct is created by the [`iter_mut`] method on [slices].
1485 /// // First, we declare a type which has `iter_mut` method to get the `IterMut`
1486 /// // struct (&[usize here]):
1487 /// let mut slice = &mut [1, 2, 3];
1489 /// // Then, we iterate over it and increment each element value:
1490 /// for element in slice.iter_mut() {
1494 /// // We now have "[2, 3, 4]":
1495 /// println!("{:?}", slice);
1498 /// [`iter_mut`]: ../../std/primitive.slice.html#method.iter_mut
1499 /// [slices]: ../../std/primitive.slice.html
1500 #[stable(feature = "rust1", since = "1.0.0")]
1501 pub struct IterMut<'a, T: 'a> {
1504 _marker: marker::PhantomData<&'a mut T>,
1507 #[stable(feature = "core_impl_debug", since = "1.9.0")]
1508 impl<'a, T: 'a + fmt::Debug> fmt::Debug for IterMut<'a, T> {
1509 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1510 f.debug_tuple("IterMut")
1511 .field(&make_slice!(self.ptr, self.end))
1516 #[stable(feature = "rust1", since = "1.0.0")]
1517 unsafe impl<'a, T: Sync> Sync for IterMut<'a, T> {}
1518 #[stable(feature = "rust1", since = "1.0.0")]
1519 unsafe impl<'a, T: Send> Send for IterMut<'a, T> {}
1521 impl<'a, T> IterMut<'a, T> {
1522 /// View the underlying data as a subslice of the original data.
1524 /// To avoid creating `&mut` references that alias, this is forced
1525 /// to consume the iterator. Consider using the `Slice` and
1526 /// `SliceMut` implementations for obtaining slices with more
1527 /// restricted lifetimes that do not consume the iterator.
1534 /// // First, we declare a type which has `iter_mut` method to get the `IterMut`
1535 /// // struct (&[usize here]):
1536 /// let mut slice = &mut [1, 2, 3];
1539 /// // Then, we get the iterator:
1540 /// let mut iter = slice.iter_mut();
1541 /// // We move to next element:
1543 /// // So if we print what `into_slice` method returns here, we have "[2, 3]":
1544 /// println!("{:?}", iter.into_slice());
1547 /// // Now let's modify a value of the slice:
1549 /// // First we get back the iterator:
1550 /// let mut iter = slice.iter_mut();
1551 /// // We change the value of the first element of the slice returned by the `next` method:
1552 /// *iter.next().unwrap() += 1;
1554 /// // Now slice is "[2, 2, 3]":
1555 /// println!("{:?}", slice);
1557 #[stable(feature = "iter_to_slice", since = "1.4.0")]
1558 pub fn into_slice(self) -> &'a mut [T] {
1559 make_mut_slice!(self.ptr, self.end)
1562 // Helper function for IterMut::nth
1563 fn iter_nth(&mut self, n: usize) -> Option<&'a mut T> {
1564 match make_mut_slice!(self.ptr, self.end).get_mut(n) {
1565 Some(elem_ref) => unsafe {
1566 self.ptr = slice_offset!(self.ptr, (n as isize).wrapping_add(1));
1570 self.ptr = self.end;
1577 iterator!{struct IterMut -> *mut T, &'a mut T, make_ref_mut}
1579 #[stable(feature = "rust1", since = "1.0.0")]
1580 impl<'a, T> ExactSizeIterator for IterMut<'a, T> {
1581 fn is_empty(&self) -> bool {
1582 self.ptr == self.end
1586 #[unstable(feature = "fused", issue = "35602")]
1587 impl<'a, T> FusedIterator for IterMut<'a, T> {}
1589 #[unstable(feature = "trusted_len", issue = "37572")]
1590 unsafe impl<'a, T> TrustedLen for IterMut<'a, T> {}
1593 // Return the number of elements of `T` from `start` to `end`.
1594 // Return the arithmetic difference if `T` is zero size.
1596 fn ptrdistance<T>(start: *const T, end: *const T) -> usize {
1597 match start.offset_to(end) {
1598 Some(x) => x as usize,
1599 None => (end as usize).wrapping_sub(start as usize),
1603 // Extension methods for raw pointers, used by the iterators
1604 trait PointerExt : Copy {
1605 unsafe fn slice_offset(self, i: isize) -> Self;
1607 /// Increments `self` by 1, but returns the old value.
1609 unsafe fn post_inc(&mut self) -> Self {
1610 let current = *self;
1611 *self = self.slice_offset(1);
1615 /// Decrements `self` by 1, and returns the new value.
1617 unsafe fn pre_dec(&mut self) -> Self {
1618 *self = self.slice_offset(-1);
1623 impl<T> PointerExt for *const T {
1625 unsafe fn slice_offset(self, i: isize) -> Self {
1626 slice_offset!(self, i)
1630 impl<T> PointerExt for *mut T {
1632 unsafe fn slice_offset(self, i: isize) -> Self {
1633 slice_offset!(self, i)
1637 /// An internal abstraction over the splitting iterators, so that
1638 /// splitn, splitn_mut etc can be implemented once.
1640 trait SplitIter: DoubleEndedIterator {
1641 /// Marks the underlying iterator as complete, extracting the remaining
1642 /// portion of the slice.
1643 fn finish(&mut self) -> Option<Self::Item>;
1646 /// An iterator over subslices separated by elements that match a predicate
1649 /// This struct is created by the [`split`] method on [slices].
1651 /// [`split`]: ../../std/primitive.slice.html#method.split
1652 /// [slices]: ../../std/primitive.slice.html
1653 #[stable(feature = "rust1", since = "1.0.0")]
1654 pub struct Split<'a, T:'a, P> where P: FnMut(&T) -> bool {
1660 #[stable(feature = "core_impl_debug", since = "1.9.0")]
1661 impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for Split<'a, T, P> where P: FnMut(&T) -> bool {
1662 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1663 f.debug_struct("Split")
1664 .field("v", &self.v)
1665 .field("finished", &self.finished)
1670 // FIXME(#19839) Remove in favor of `#[derive(Clone)]`
1671 #[stable(feature = "rust1", since = "1.0.0")]
1672 impl<'a, T, P> Clone for Split<'a, T, P> where P: Clone + FnMut(&T) -> bool {
1673 fn clone(&self) -> Split<'a, T, P> {
1676 pred: self.pred.clone(),
1677 finished: self.finished,
1682 #[stable(feature = "rust1", since = "1.0.0")]
1683 impl<'a, T, P> Iterator for Split<'a, T, P> where P: FnMut(&T) -> bool {
1684 type Item = &'a [T];
1687 fn next(&mut self) -> Option<&'a [T]> {
1688 if self.finished { return None; }
1690 match self.v.iter().position(|x| (self.pred)(x)) {
1691 None => self.finish(),
1693 let ret = Some(&self.v[..idx]);
1694 self.v = &self.v[idx + 1..];
1701 fn size_hint(&self) -> (usize, Option<usize>) {
1705 (1, Some(self.v.len() + 1))
1710 #[stable(feature = "rust1", since = "1.0.0")]
1711 impl<'a, T, P> DoubleEndedIterator for Split<'a, T, P> where P: FnMut(&T) -> bool {
1713 fn next_back(&mut self) -> Option<&'a [T]> {
1714 if self.finished { return None; }
1716 match self.v.iter().rposition(|x| (self.pred)(x)) {
1717 None => self.finish(),
1719 let ret = Some(&self.v[idx + 1..]);
1720 self.v = &self.v[..idx];
1727 impl<'a, T, P> SplitIter for Split<'a, T, P> where P: FnMut(&T) -> bool {
1729 fn finish(&mut self) -> Option<&'a [T]> {
1730 if self.finished { None } else { self.finished = true; Some(self.v) }
1734 #[unstable(feature = "fused", issue = "35602")]
1735 impl<'a, T, P> FusedIterator for Split<'a, T, P> where P: FnMut(&T) -> bool {}
1737 /// An iterator over the subslices of the vector which are separated
1738 /// by elements that match `pred`.
1740 /// This struct is created by the [`split_mut`] method on [slices].
1742 /// [`split_mut`]: ../../std/primitive.slice.html#method.split_mut
1743 /// [slices]: ../../std/primitive.slice.html
1744 #[stable(feature = "rust1", since = "1.0.0")]
1745 pub struct SplitMut<'a, T:'a, P> where P: FnMut(&T) -> bool {
1751 #[stable(feature = "core_impl_debug", since = "1.9.0")]
1752 impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {
1753 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1754 f.debug_struct("SplitMut")
1755 .field("v", &self.v)
1756 .field("finished", &self.finished)
1761 impl<'a, T, P> SplitIter for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {
1763 fn finish(&mut self) -> Option<&'a mut [T]> {
1767 self.finished = true;
1768 Some(mem::replace(&mut self.v, &mut []))
1773 #[stable(feature = "rust1", since = "1.0.0")]
1774 impl<'a, T, P> Iterator for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {
1775 type Item = &'a mut [T];
1778 fn next(&mut self) -> Option<&'a mut [T]> {
1779 if self.finished { return None; }
1781 let idx_opt = { // work around borrowck limitations
1782 let pred = &mut self.pred;
1783 self.v.iter().position(|x| (*pred)(x))
1786 None => self.finish(),
1788 let tmp = mem::replace(&mut self.v, &mut []);
1789 let (head, tail) = tmp.split_at_mut(idx);
1790 self.v = &mut tail[1..];
1797 fn size_hint(&self) -> (usize, Option<usize>) {
1801 // if the predicate doesn't match anything, we yield one slice
1802 // if it matches every element, we yield len+1 empty slices.
1803 (1, Some(self.v.len() + 1))
1808 #[stable(feature = "rust1", since = "1.0.0")]
1809 impl<'a, T, P> DoubleEndedIterator for SplitMut<'a, T, P> where
1810 P: FnMut(&T) -> bool,
1813 fn next_back(&mut self) -> Option<&'a mut [T]> {
1814 if self.finished { return None; }
1816 let idx_opt = { // work around borrowck limitations
1817 let pred = &mut self.pred;
1818 self.v.iter().rposition(|x| (*pred)(x))
1821 None => self.finish(),
1823 let tmp = mem::replace(&mut self.v, &mut []);
1824 let (head, tail) = tmp.split_at_mut(idx);
1826 Some(&mut tail[1..])
1832 #[unstable(feature = "fused", issue = "35602")]
1833 impl<'a, T, P> FusedIterator for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {}
1835 /// An iterator over subslices separated by elements that match a predicate
1836 /// function, starting from the end of the slice.
1838 /// This struct is created by the [`rsplit`] method on [slices].
1840 /// [`rsplit`]: ../../std/primitive.slice.html#method.rsplit
1841 /// [slices]: ../../std/primitive.slice.html
1842 #[unstable(feature = "slice_rsplit", issue = "41020")]
1843 #[derive(Clone)] // Is this correct, or does it incorrectly require `T: Clone`?
1844 pub struct RSplit<'a, T:'a, P> where P: FnMut(&T) -> bool {
1845 inner: Split<'a, T, P>
1848 #[unstable(feature = "slice_rsplit", issue = "41020")]
1849 impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for RSplit<'a, T, P> where P: FnMut(&T) -> bool {
1850 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1851 f.debug_struct("RSplit")
1852 .field("v", &self.inner.v)
1853 .field("finished", &self.inner.finished)
1858 #[unstable(feature = "slice_rsplit", issue = "41020")]
1859 impl<'a, T, P> Iterator for RSplit<'a, T, P> where P: FnMut(&T) -> bool {
1860 type Item = &'a [T];
1863 fn next(&mut self) -> Option<&'a [T]> {
1864 self.inner.next_back()
1868 fn size_hint(&self) -> (usize, Option<usize>) {
1869 self.inner.size_hint()
1873 #[unstable(feature = "slice_rsplit", issue = "41020")]
1874 impl<'a, T, P> DoubleEndedIterator for RSplit<'a, T, P> where P: FnMut(&T) -> bool {
1876 fn next_back(&mut self) -> Option<&'a [T]> {
1881 #[unstable(feature = "slice_rsplit", issue = "41020")]
1882 impl<'a, T, P> SplitIter for RSplit<'a, T, P> where P: FnMut(&T) -> bool {
1884 fn finish(&mut self) -> Option<&'a [T]> {
1889 //#[unstable(feature = "fused", issue = "35602")]
1890 #[unstable(feature = "slice_rsplit", issue = "41020")]
1891 impl<'a, T, P> FusedIterator for RSplit<'a, T, P> where P: FnMut(&T) -> bool {}
1893 /// An iterator over the subslices of the vector which are separated
1894 /// by elements that match `pred`, starting from the end of the slice.
1896 /// This struct is created by the [`rsplit_mut`] method on [slices].
1898 /// [`rsplit_mut`]: ../../std/primitive.slice.html#method.rsplit_mut
1899 /// [slices]: ../../std/primitive.slice.html
1900 #[unstable(feature = "slice_rsplit", issue = "41020")]
1901 pub struct RSplitMut<'a, T:'a, P> where P: FnMut(&T) -> bool {
1902 inner: SplitMut<'a, T, P>
1905 #[unstable(feature = "slice_rsplit", issue = "41020")]
1906 impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for RSplitMut<'a, T, P> where P: FnMut(&T) -> bool {
1907 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1908 f.debug_struct("RSplitMut")
1909 .field("v", &self.inner.v)
1910 .field("finished", &self.inner.finished)
1915 #[unstable(feature = "slice_rsplit", issue = "41020")]
1916 impl<'a, T, P> SplitIter for RSplitMut<'a, T, P> where P: FnMut(&T) -> bool {
1918 fn finish(&mut self) -> Option<&'a mut [T]> {
1923 #[unstable(feature = "slice_rsplit", issue = "41020")]
1924 impl<'a, T, P> Iterator for RSplitMut<'a, T, P> where P: FnMut(&T) -> bool {
1925 type Item = &'a mut [T];
1928 fn next(&mut self) -> Option<&'a mut [T]> {
1929 self.inner.next_back()
1933 fn size_hint(&self) -> (usize, Option<usize>) {
1934 self.inner.size_hint()
1938 #[unstable(feature = "slice_rsplit", issue = "41020")]
1939 impl<'a, T, P> DoubleEndedIterator for RSplitMut<'a, T, P> where
1940 P: FnMut(&T) -> bool,
1943 fn next_back(&mut self) -> Option<&'a mut [T]> {
1948 //#[unstable(feature = "fused", issue = "35602")]
1949 #[unstable(feature = "slice_rsplit", issue = "41020")]
1950 impl<'a, T, P> FusedIterator for RSplitMut<'a, T, P> where P: FnMut(&T) -> bool {}
1952 /// An private iterator over subslices separated by elements that
1953 /// match a predicate function, splitting at most a fixed number of
1956 struct GenericSplitN<I> {
1961 impl<T, I: SplitIter<Item=T>> Iterator for GenericSplitN<I> {
1965 fn next(&mut self) -> Option<T> {
1968 1 => { self.count -= 1; self.iter.finish() }
1969 _ => { self.count -= 1; self.iter.next() }
1974 fn size_hint(&self) -> (usize, Option<usize>) {
1975 let (lower, upper_opt) = self.iter.size_hint();
1976 (lower, upper_opt.map(|upper| cmp::min(self.count, upper)))
1980 /// An iterator over subslices separated by elements that match a predicate
1981 /// function, limited to a given number of splits.
1983 /// This struct is created by the [`splitn`] method on [slices].
1985 /// [`splitn`]: ../../std/primitive.slice.html#method.splitn
1986 /// [slices]: ../../std/primitive.slice.html
1987 #[stable(feature = "rust1", since = "1.0.0")]
1988 pub struct SplitN<'a, T: 'a, P> where P: FnMut(&T) -> bool {
1989 inner: GenericSplitN<Split<'a, T, P>>
1992 #[stable(feature = "core_impl_debug", since = "1.9.0")]
1993 impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for SplitN<'a, T, P> where P: FnMut(&T) -> bool {
1994 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1995 f.debug_struct("SplitN")
1996 .field("inner", &self.inner)
2001 /// An iterator over subslices separated by elements that match a
2002 /// predicate function, limited to a given number of splits, starting
2003 /// from the end of the slice.
2005 /// This struct is created by the [`rsplitn`] method on [slices].
2007 /// [`rsplitn`]: ../../std/primitive.slice.html#method.rsplitn
2008 /// [slices]: ../../std/primitive.slice.html
2009 #[stable(feature = "rust1", since = "1.0.0")]
2010 pub struct RSplitN<'a, T: 'a, P> where P: FnMut(&T) -> bool {
2011 inner: GenericSplitN<RSplit<'a, T, P>>
2014 #[stable(feature = "core_impl_debug", since = "1.9.0")]
2015 impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for RSplitN<'a, T, P> where P: FnMut(&T) -> bool {
2016 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
2017 f.debug_struct("RSplitN")
2018 .field("inner", &self.inner)
2023 /// An iterator over subslices separated by elements that match a predicate
2024 /// function, limited to a given number of splits.
2026 /// This struct is created by the [`splitn_mut`] method on [slices].
2028 /// [`splitn_mut`]: ../../std/primitive.slice.html#method.splitn_mut
2029 /// [slices]: ../../std/primitive.slice.html
2030 #[stable(feature = "rust1", since = "1.0.0")]
2031 pub struct SplitNMut<'a, T: 'a, P> where P: FnMut(&T) -> bool {
2032 inner: GenericSplitN<SplitMut<'a, T, P>>
2035 #[stable(feature = "core_impl_debug", since = "1.9.0")]
2036 impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for SplitNMut<'a, T, P> where P: FnMut(&T) -> bool {
2037 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
2038 f.debug_struct("SplitNMut")
2039 .field("inner", &self.inner)
2044 /// An iterator over subslices separated by elements that match a
2045 /// predicate function, limited to a given number of splits, starting
2046 /// from the end of the slice.
2048 /// This struct is created by the [`rsplitn_mut`] method on [slices].
2050 /// [`rsplitn_mut`]: ../../std/primitive.slice.html#method.rsplitn_mut
2051 /// [slices]: ../../std/primitive.slice.html
2052 #[stable(feature = "rust1", since = "1.0.0")]
2053 pub struct RSplitNMut<'a, T: 'a, P> where P: FnMut(&T) -> bool {
2054 inner: GenericSplitN<RSplitMut<'a, T, P>>
2057 #[stable(feature = "core_impl_debug", since = "1.9.0")]
2058 impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for RSplitNMut<'a, T, P> where P: FnMut(&T) -> bool {
2059 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
2060 f.debug_struct("RSplitNMut")
2061 .field("inner", &self.inner)
2066 macro_rules! forward_iterator {
2067 ($name:ident: $elem:ident, $iter_of:ty) => {
2068 #[stable(feature = "rust1", since = "1.0.0")]
2069 impl<'a, $elem, P> Iterator for $name<'a, $elem, P> where
2070 P: FnMut(&T) -> bool
2072 type Item = $iter_of;
2075 fn next(&mut self) -> Option<$iter_of> {
2080 fn size_hint(&self) -> (usize, Option<usize>) {
2081 self.inner.size_hint()
2085 #[unstable(feature = "fused", issue = "35602")]
2086 impl<'a, $elem, P> FusedIterator for $name<'a, $elem, P>
2087 where P: FnMut(&T) -> bool {}
2091 forward_iterator! { SplitN: T, &'a [T] }
2092 forward_iterator! { RSplitN: T, &'a [T] }
2093 forward_iterator! { SplitNMut: T, &'a mut [T] }
2094 forward_iterator! { RSplitNMut: T, &'a mut [T] }
2096 /// An iterator over overlapping subslices of length `size`.
2098 /// This struct is created by the [`windows`] method on [slices].
2100 /// [`windows`]: ../../std/primitive.slice.html#method.windows
2101 /// [slices]: ../../std/primitive.slice.html
2103 #[stable(feature = "rust1", since = "1.0.0")]
2104 pub struct Windows<'a, T:'a> {
2109 // FIXME(#19839) Remove in favor of `#[derive(Clone)]`
2110 #[stable(feature = "rust1", since = "1.0.0")]
2111 impl<'a, T> Clone for Windows<'a, T> {
2112 fn clone(&self) -> Windows<'a, T> {
2120 #[stable(feature = "rust1", since = "1.0.0")]
2121 impl<'a, T> Iterator for Windows<'a, T> {
2122 type Item = &'a [T];
2125 fn next(&mut self) -> Option<&'a [T]> {
2126 if self.size > self.v.len() {
2129 let ret = Some(&self.v[..self.size]);
2130 self.v = &self.v[1..];
2136 fn size_hint(&self) -> (usize, Option<usize>) {
2137 if self.size > self.v.len() {
2140 let size = self.v.len() - self.size + 1;
2146 fn count(self) -> usize {
2151 fn nth(&mut self, n: usize) -> Option<Self::Item> {
2152 let (end, overflow) = self.size.overflowing_add(n);
2153 if end > self.v.len() || overflow {
2157 let nth = &self.v[n..end];
2158 self.v = &self.v[n+1..];
2164 fn last(self) -> Option<Self::Item> {
2165 if self.size > self.v.len() {
2168 let start = self.v.len() - self.size;
2169 Some(&self.v[start..])
2174 #[stable(feature = "rust1", since = "1.0.0")]
2175 impl<'a, T> DoubleEndedIterator for Windows<'a, T> {
2177 fn next_back(&mut self) -> Option<&'a [T]> {
2178 if self.size > self.v.len() {
2181 let ret = Some(&self.v[self.v.len()-self.size..]);
2182 self.v = &self.v[..self.v.len()-1];
2188 #[stable(feature = "rust1", since = "1.0.0")]
2189 impl<'a, T> ExactSizeIterator for Windows<'a, T> {}
2191 #[unstable(feature = "fused", issue = "35602")]
2192 impl<'a, T> FusedIterator for Windows<'a, T> {}
2194 /// An iterator over a slice in (non-overlapping) chunks (`size` elements at a
2197 /// When the slice len is not evenly divided by the chunk size, the last slice
2198 /// of the iteration will be the remainder.
2200 /// This struct is created by the [`chunks`] method on [slices].
2202 /// [`chunks`]: ../../std/primitive.slice.html#method.chunks
2203 /// [slices]: ../../std/primitive.slice.html
2205 #[stable(feature = "rust1", since = "1.0.0")]
2206 pub struct Chunks<'a, T:'a> {
2211 // FIXME(#19839) Remove in favor of `#[derive(Clone)]`
2212 #[stable(feature = "rust1", since = "1.0.0")]
2213 impl<'a, T> Clone for Chunks<'a, T> {
2214 fn clone(&self) -> Chunks<'a, T> {
2222 #[stable(feature = "rust1", since = "1.0.0")]
2223 impl<'a, T> Iterator for Chunks<'a, T> {
2224 type Item = &'a [T];
2227 fn next(&mut self) -> Option<&'a [T]> {
2228 if self.v.is_empty() {
2231 let chunksz = cmp::min(self.v.len(), self.size);
2232 let (fst, snd) = self.v.split_at(chunksz);
2239 fn size_hint(&self) -> (usize, Option<usize>) {
2240 if self.v.is_empty() {
2243 let n = self.v.len() / self.size;
2244 let rem = self.v.len() % self.size;
2245 let n = if rem > 0 { n+1 } else { n };
2251 fn count(self) -> usize {
2256 fn nth(&mut self, n: usize) -> Option<Self::Item> {
2257 let (start, overflow) = n.overflowing_mul(self.size);
2258 if start >= self.v.len() || overflow {
2262 let end = match start.checked_add(self.size) {
2263 Some(sum) => cmp::min(self.v.len(), sum),
2264 None => self.v.len(),
2266 let nth = &self.v[start..end];
2267 self.v = &self.v[end..];
2273 fn last(self) -> Option<Self::Item> {
2274 if self.v.is_empty() {
2277 let start = (self.v.len() - 1) / self.size * self.size;
2278 Some(&self.v[start..])
2283 #[stable(feature = "rust1", since = "1.0.0")]
2284 impl<'a, T> DoubleEndedIterator for Chunks<'a, T> {
2286 fn next_back(&mut self) -> Option<&'a [T]> {
2287 if self.v.is_empty() {
2290 let remainder = self.v.len() % self.size;
2291 let chunksz = if remainder != 0 { remainder } else { self.size };
2292 let (fst, snd) = self.v.split_at(self.v.len() - chunksz);
2299 #[stable(feature = "rust1", since = "1.0.0")]
2300 impl<'a, T> ExactSizeIterator for Chunks<'a, T> {}
2302 #[unstable(feature = "fused", issue = "35602")]
2303 impl<'a, T> FusedIterator for Chunks<'a, T> {}
2305 /// An iterator over a slice in (non-overlapping) mutable chunks (`size`
2306 /// elements at a time). When the slice len is not evenly divided by the chunk
2307 /// size, the last slice of the iteration will be the remainder.
2309 /// This struct is created by the [`chunks_mut`] method on [slices].
2311 /// [`chunks_mut`]: ../../std/primitive.slice.html#method.chunks_mut
2312 /// [slices]: ../../std/primitive.slice.html
2314 #[stable(feature = "rust1", since = "1.0.0")]
2315 pub struct ChunksMut<'a, T:'a> {
2320 #[stable(feature = "rust1", since = "1.0.0")]
2321 impl<'a, T> Iterator for ChunksMut<'a, T> {
2322 type Item = &'a mut [T];
2325 fn next(&mut self) -> Option<&'a mut [T]> {
2326 if self.v.is_empty() {
2329 let sz = cmp::min(self.v.len(), self.chunk_size);
2330 let tmp = mem::replace(&mut self.v, &mut []);
2331 let (head, tail) = tmp.split_at_mut(sz);
2338 fn size_hint(&self) -> (usize, Option<usize>) {
2339 if self.v.is_empty() {
2342 let n = self.v.len() / self.chunk_size;
2343 let rem = self.v.len() % self.chunk_size;
2344 let n = if rem > 0 { n + 1 } else { n };
2350 fn count(self) -> usize {
2355 fn nth(&mut self, n: usize) -> Option<&'a mut [T]> {
2356 let (start, overflow) = n.overflowing_mul(self.chunk_size);
2357 if start >= self.v.len() || overflow {
2361 let end = match start.checked_add(self.chunk_size) {
2362 Some(sum) => cmp::min(self.v.len(), sum),
2363 None => self.v.len(),
2365 let tmp = mem::replace(&mut self.v, &mut []);
2366 let (head, tail) = tmp.split_at_mut(end);
2367 let (_, nth) = head.split_at_mut(start);
2374 fn last(self) -> Option<Self::Item> {
2375 if self.v.is_empty() {
2378 let start = (self.v.len() - 1) / self.chunk_size * self.chunk_size;
2379 Some(&mut self.v[start..])
2384 #[stable(feature = "rust1", since = "1.0.0")]
2385 impl<'a, T> DoubleEndedIterator for ChunksMut<'a, T> {
2387 fn next_back(&mut self) -> Option<&'a mut [T]> {
2388 if self.v.is_empty() {
2391 let remainder = self.v.len() % self.chunk_size;
2392 let sz = if remainder != 0 { remainder } else { self.chunk_size };
2393 let tmp = mem::replace(&mut self.v, &mut []);
2394 let tmp_len = tmp.len();
2395 let (head, tail) = tmp.split_at_mut(tmp_len - sz);
2402 #[stable(feature = "rust1", since = "1.0.0")]
2403 impl<'a, T> ExactSizeIterator for ChunksMut<'a, T> {}
2405 #[unstable(feature = "fused", issue = "35602")]
2406 impl<'a, T> FusedIterator for ChunksMut<'a, T> {}
2412 /// Forms a slice from a pointer and a length.
2414 /// The `len` argument is the number of **elements**, not the number of bytes.
2418 /// This function is unsafe as there is no guarantee that the given pointer is
2419 /// valid for `len` elements, nor whether the lifetime inferred is a suitable
2420 /// lifetime for the returned slice.
2422 /// `p` must be non-null, even for zero-length slices, because non-zero bits
2423 /// are required to distinguish between a zero-length slice within `Some()`
2424 /// from `None`. `p` can be a bogus non-dereferencable pointer, such as `0x1`,
2425 /// for zero-length slices, though.
2429 /// The lifetime for the returned slice is inferred from its usage. To
2430 /// prevent accidental misuse, it's suggested to tie the lifetime to whichever
2431 /// source lifetime is safe in the context, such as by providing a helper
2432 /// function taking the lifetime of a host value for the slice, or by explicit
2440 /// // manifest a slice out of thin air!
2441 /// let ptr = 0x1234 as *const usize;
2444 /// let slice = slice::from_raw_parts(ptr, amt);
2448 #[stable(feature = "rust1", since = "1.0.0")]
2449 pub unsafe fn from_raw_parts<'a, T>(p: *const T, len: usize) -> &'a [T] {
2450 mem::transmute(Repr { data: p, len: len })
2453 /// Performs the same functionality as `from_raw_parts`, except that a mutable
2454 /// slice is returned.
2456 /// This function is unsafe for the same reasons as `from_raw_parts`, as well
2457 /// as not being able to provide a non-aliasing guarantee of the returned
2458 /// mutable slice. `p` must be non-null even for zero-length slices as with
2459 /// `from_raw_parts`.
2461 #[stable(feature = "rust1", since = "1.0.0")]
2462 pub unsafe fn from_raw_parts_mut<'a, T>(p: *mut T, len: usize) -> &'a mut [T] {
2463 mem::transmute(Repr { data: p, len: len })
2466 // This function is public only because there is no other way to unit test heapsort.
2467 #[unstable(feature = "sort_internals", reason = "internal to sort module", issue = "0")]
2469 pub fn heapsort<T, F>(v: &mut [T], mut is_less: F)
2470 where F: FnMut(&T, &T) -> bool
2472 sort::heapsort(v, &mut is_less);
2476 // Comparison traits
2480 /// Calls implementation provided memcmp.
2482 /// Interprets the data as u8.
2484 /// Returns 0 for equal, < 0 for less than and > 0 for greater
2486 // FIXME(#32610): Return type should be c_int
2487 fn memcmp(s1: *const u8, s2: *const u8, n: usize) -> i32;
2490 #[stable(feature = "rust1", since = "1.0.0")]
2491 impl<A, B> PartialEq<[B]> for [A] where A: PartialEq<B> {
2492 fn eq(&self, other: &[B]) -> bool {
2493 SlicePartialEq::equal(self, other)
2496 fn ne(&self, other: &[B]) -> bool {
2497 SlicePartialEq::not_equal(self, other)
2501 #[stable(feature = "rust1", since = "1.0.0")]
2502 impl<T: Eq> Eq for [T] {}
2504 /// Implements comparison of vectors lexicographically.
2505 #[stable(feature = "rust1", since = "1.0.0")]
2506 impl<T: Ord> Ord for [T] {
2507 fn cmp(&self, other: &[T]) -> Ordering {
2508 SliceOrd::compare(self, other)
2512 /// Implements comparison of vectors lexicographically.
2513 #[stable(feature = "rust1", since = "1.0.0")]
2514 impl<T: PartialOrd> PartialOrd for [T] {
2515 fn partial_cmp(&self, other: &[T]) -> Option<Ordering> {
2516 SlicePartialOrd::partial_compare(self, other)
2521 // intermediate trait for specialization of slice's PartialEq
2522 trait SlicePartialEq<B> {
2523 fn equal(&self, other: &[B]) -> bool;
2525 fn not_equal(&self, other: &[B]) -> bool { !self.equal(other) }
2528 // Generic slice equality
2529 impl<A, B> SlicePartialEq<B> for [A]
2530 where A: PartialEq<B>
2532 default fn equal(&self, other: &[B]) -> bool {
2533 if self.len() != other.len() {
2537 for i in 0..self.len() {
2538 if !self[i].eq(&other[i]) {
2547 // Use memcmp for bytewise equality when the types allow
2548 impl<A> SlicePartialEq<A> for [A]
2549 where A: PartialEq<A> + BytewiseEquality
2551 fn equal(&self, other: &[A]) -> bool {
2552 if self.len() != other.len() {
2555 if self.as_ptr() == other.as_ptr() {
2559 let size = mem::size_of_val(self);
2560 memcmp(self.as_ptr() as *const u8,
2561 other.as_ptr() as *const u8, size) == 0
2567 // intermediate trait for specialization of slice's PartialOrd
2568 trait SlicePartialOrd<B> {
2569 fn partial_compare(&self, other: &[B]) -> Option<Ordering>;
2572 impl<A> SlicePartialOrd<A> for [A]
2575 default fn partial_compare(&self, other: &[A]) -> Option<Ordering> {
2576 let l = cmp::min(self.len(), other.len());
2578 // Slice to the loop iteration range to enable bound check
2579 // elimination in the compiler
2580 let lhs = &self[..l];
2581 let rhs = &other[..l];
2584 match lhs[i].partial_cmp(&rhs[i]) {
2585 Some(Ordering::Equal) => (),
2586 non_eq => return non_eq,
2590 self.len().partial_cmp(&other.len())
2594 impl<A> SlicePartialOrd<A> for [A]
2597 default fn partial_compare(&self, other: &[A]) -> Option<Ordering> {
2598 Some(SliceOrd::compare(self, other))
2603 // intermediate trait for specialization of slice's Ord
2605 fn compare(&self, other: &[B]) -> Ordering;
2608 impl<A> SliceOrd<A> for [A]
2611 default fn compare(&self, other: &[A]) -> Ordering {
2612 let l = cmp::min(self.len(), other.len());
2614 // Slice to the loop iteration range to enable bound check
2615 // elimination in the compiler
2616 let lhs = &self[..l];
2617 let rhs = &other[..l];
2620 match lhs[i].cmp(&rhs[i]) {
2621 Ordering::Equal => (),
2622 non_eq => return non_eq,
2626 self.len().cmp(&other.len())
2630 // memcmp compares a sequence of unsigned bytes lexicographically.
2631 // this matches the order we want for [u8], but no others (not even [i8]).
2632 impl SliceOrd<u8> for [u8] {
2634 fn compare(&self, other: &[u8]) -> Ordering {
2635 let order = unsafe {
2636 memcmp(self.as_ptr(), other.as_ptr(),
2637 cmp::min(self.len(), other.len()))
2640 self.len().cmp(&other.len())
2641 } else if order < 0 {
2650 /// Trait implemented for types that can be compared for equality using
2651 /// their bytewise representation
2652 trait BytewiseEquality { }
2654 macro_rules! impl_marker_for {
2655 ($traitname:ident, $($ty:ty)*) => {
2657 impl $traitname for $ty { }
2662 impl_marker_for!(BytewiseEquality,
2663 u8 i8 u16 i16 u32 i32 u64 i64 usize isize char bool);
2666 unsafe impl<'a, T> TrustedRandomAccess for Iter<'a, T> {
2667 unsafe fn get_unchecked(&mut self, i: usize) -> &'a T {
2668 &*self.ptr.offset(i as isize)
2670 fn may_have_side_effect() -> bool { false }
2674 unsafe impl<'a, T> TrustedRandomAccess for IterMut<'a, T> {
2675 unsafe fn get_unchecked(&mut self, i: usize) -> &'a mut T {
2676 &mut *self.ptr.offset(i as isize)
2678 fn may_have_side_effect() -> bool { false }