1 // Copyright 2012-2015 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 //! A dynamically-sized view into a contiguous sequence, `[T]`.
13 //! Slices are a view into a block of memory represented as a pointer and a
18 //! let vec = vec![1, 2, 3];
19 //! let int_slice = &vec[..];
20 //! // coercing an array to a slice
21 //! let str_slice: &[&str] = &["one", "two", "three"];
24 //! Slices are either mutable or shared. The shared slice type is `&[T]`,
25 //! while the mutable slice type is `&mut [T]`, where `T` represents the element
26 //! type. For example, you can mutate the block of memory that a mutable slice
30 //! let x = &mut [1, 2, 3];
32 //! assert_eq!(x, &[1, 7, 3]);
35 //! Here are some of the things this module contains:
39 //! There are several structs that are useful for slices, such as `Iter`, which
40 //! represents iteration over a slice.
42 //! ## Trait Implementations
44 //! There are several implementations of common traits for slices. Some examples
48 //! * `Eq`, `Ord` - for slices whose element type are `Eq` or `Ord`.
49 //! * `Hash` - for slices whose element type is `Hash`
53 //! The slices implement `IntoIterator`. The iterator yields references to the
57 //! let numbers = &[0, 1, 2];
58 //! for n in numbers {
59 //! println!("{} is a number!", n);
63 //! The mutable slice yields mutable references to the elements:
66 //! let mut scores = [7, 8, 9];
67 //! for score in &mut scores[..] {
72 //! This iterator yields mutable references to the slice's elements, so while
73 //! the element type of the slice is `i32`, the element type of the iterator is
76 //! * `.iter()` and `.iter_mut()` are the explicit methods to return the default
78 //! * Further methods that return iterators are `.split()`, `.splitn()`,
79 //! `.chunks()`, `.windows()` and more.
81 //! *[See also the slice primitive type](../../std/primitive.slice.html).*
82 #![stable(feature = "rust1", since = "1.0.0")]
84 // Many of the usings in this module are only used in the test configuration.
85 // It's cleaner to just turn off the unused_imports warning than to fix them.
86 #![cfg_attr(test, allow(unused_imports, dead_code))]
88 use alloc
::boxed
::Box
;
89 use core
::cmp
::Ordering
::{self, Greater, Less}
;
91 use core
::mem
::size_of
;
94 use core
::slice
as core_slice
;
96 use borrow
::{Borrow, BorrowMut, ToOwned}
;
99 #[stable(feature = "rust1", since = "1.0.0")]
100 pub use core
::slice
::{Chunks, Windows}
;
101 #[stable(feature = "rust1", since = "1.0.0")]
102 pub use core
::slice
::{Iter, IterMut}
;
103 #[stable(feature = "rust1", since = "1.0.0")]
104 pub use core
::slice
::{SplitMut, ChunksMut, Split}
;
105 #[stable(feature = "rust1", since = "1.0.0")]
106 pub use core
::slice
::{SplitN, RSplitN, SplitNMut, RSplitNMut}
;
107 #[stable(feature = "rust1", since = "1.0.0")]
108 pub use core
::slice
::{from_raw_parts, from_raw_parts_mut}
;
110 ////////////////////////////////////////////////////////////////////////////////
111 // Basic slice extension methods
112 ////////////////////////////////////////////////////////////////////////////////
114 // HACK(japaric) needed for the implementation of `vec!` macro during testing
115 // NB see the hack module in this file for more details
117 pub use self::hack
::into_vec
;
119 // HACK(japaric) needed for the implementation of `Vec::clone` during testing
120 // NB see the hack module in this file for more details
122 pub use self::hack
::to_vec
;
124 // HACK(japaric): With cfg(test) `impl [T]` is not available, these three
125 // functions are actually methods that are in `impl [T]` but not in
126 // `core::slice::SliceExt` - we need to supply these functions for the
127 // `test_permutations` test
129 use alloc
::boxed
::Box
;
133 use string
::ToString
;
136 pub fn into_vec
<T
>(mut b
: Box
<[T
]>) -> Vec
<T
> {
138 let xs
= Vec
::from_raw_parts(b
.as_mut_ptr(), b
.len(), b
.len());
145 pub fn to_vec
<T
>(s
: &[T
]) -> Vec
<T
>
148 let mut vector
= Vec
::with_capacity(s
.len());
149 vector
.extend_from_slice(s
);
157 /// Returns the number of elements in the slice.
162 /// let a = [1, 2, 3];
163 /// assert_eq!(a.len(), 3);
165 #[stable(feature = "rust1", since = "1.0.0")]
167 pub fn len(&self) -> usize {
168 core_slice
::SliceExt
::len(self)
171 /// Returns true if the slice has a length of 0
176 /// let a = [1, 2, 3];
177 /// assert!(!a.is_empty());
179 #[stable(feature = "rust1", since = "1.0.0")]
181 pub fn is_empty(&self) -> bool
{
182 core_slice
::SliceExt
::is_empty(self)
185 /// Returns the first element of a slice, or `None` if it is empty.
190 /// let v = [10, 40, 30];
191 /// assert_eq!(Some(&10), v.first());
193 /// let w: &[i32] = &[];
194 /// assert_eq!(None, w.first());
196 #[stable(feature = "rust1", since = "1.0.0")]
198 pub fn first(&self) -> Option
<&T
> {
199 core_slice
::SliceExt
::first(self)
202 /// Returns a mutable pointer to the first element of a slice, or `None` if it is empty.
207 /// let x = &mut [0, 1, 2];
209 /// if let Some(first) = x.first_mut() {
212 /// assert_eq!(x, &[5, 1, 2]);
214 #[stable(feature = "rust1", since = "1.0.0")]
216 pub fn first_mut(&mut self) -> Option
<&mut T
> {
217 core_slice
::SliceExt
::first_mut(self)
220 /// Returns the first and all the rest of the elements of a slice.
225 /// let x = &[0, 1, 2];
227 /// if let Some((first, elements)) = x.split_first() {
228 /// assert_eq!(first, &0);
229 /// assert_eq!(elements, &[1, 2]);
232 #[stable(feature = "slice_splits", since = "1.5.0")]
234 pub fn split_first(&self) -> Option
<(&T
, &[T
])> {
235 core_slice
::SliceExt
::split_first(self)
238 /// Returns the first and all the rest of the elements of a slice.
243 /// let x = &mut [0, 1, 2];
245 /// if let Some((first, elements)) = x.split_first_mut() {
250 /// assert_eq!(x, &[3, 4, 5]);
252 #[stable(feature = "slice_splits", since = "1.5.0")]
254 pub fn split_first_mut(&mut self) -> Option
<(&mut T
, &mut [T
])> {
255 core_slice
::SliceExt
::split_first_mut(self)
258 /// Returns the last and all the rest of the elements of a slice.
263 /// let x = &[0, 1, 2];
265 /// if let Some((last, elements)) = x.split_last() {
266 /// assert_eq!(last, &2);
267 /// assert_eq!(elements, &[0, 1]);
270 #[stable(feature = "slice_splits", since = "1.5.0")]
272 pub fn split_last(&self) -> Option
<(&T
, &[T
])> {
273 core_slice
::SliceExt
::split_last(self)
277 /// Returns the last and all the rest of the elements of a slice.
282 /// let x = &mut [0, 1, 2];
284 /// if let Some((last, elements)) = x.split_last_mut() {
289 /// assert_eq!(x, &[4, 5, 3]);
291 #[stable(feature = "slice_splits", since = "1.5.0")]
293 pub fn split_last_mut(&mut self) -> Option
<(&mut T
, &mut [T
])> {
294 core_slice
::SliceExt
::split_last_mut(self)
297 /// Returns the last element of a slice, or `None` if it is empty.
302 /// let v = [10, 40, 30];
303 /// assert_eq!(Some(&30), v.last());
305 /// let w: &[i32] = &[];
306 /// assert_eq!(None, w.last());
308 #[stable(feature = "rust1", since = "1.0.0")]
310 pub fn last(&self) -> Option
<&T
> {
311 core_slice
::SliceExt
::last(self)
314 /// Returns a mutable pointer to the last item in the slice.
319 /// let x = &mut [0, 1, 2];
321 /// if let Some(last) = x.last_mut() {
324 /// assert_eq!(x, &[0, 1, 10]);
326 #[stable(feature = "rust1", since = "1.0.0")]
328 pub fn last_mut(&mut self) -> Option
<&mut T
> {
329 core_slice
::SliceExt
::last_mut(self)
332 /// Returns the element of a slice at the given index, or `None` if the
333 /// index is out of bounds.
338 /// let v = [10, 40, 30];
339 /// assert_eq!(Some(&40), v.get(1));
340 /// assert_eq!(None, v.get(3));
342 #[stable(feature = "rust1", since = "1.0.0")]
344 pub fn get(&self, index
: usize) -> Option
<&T
> {
345 core_slice
::SliceExt
::get(self, index
)
348 /// Returns a mutable reference to the element at the given index.
353 /// let x = &mut [0, 1, 2];
355 /// if let Some(elem) = x.get_mut(1) {
358 /// assert_eq!(x, &[0, 42, 2]);
360 /// or `None` if the index is out of bounds
361 #[stable(feature = "rust1", since = "1.0.0")]
363 pub fn get_mut(&mut self, index
: usize) -> Option
<&mut T
> {
364 core_slice
::SliceExt
::get_mut(self, index
)
367 /// Returns a pointer to the element at the given index, without doing
368 /// bounds checking. So use it very carefully!
373 /// let x = &[1, 2, 4];
376 /// assert_eq!(x.get_unchecked(1), &2);
379 #[stable(feature = "rust1", since = "1.0.0")]
381 pub unsafe fn get_unchecked(&self, index
: usize) -> &T
{
382 core_slice
::SliceExt
::get_unchecked(self, index
)
385 /// Returns an unsafe mutable pointer to the element in index. So use it
391 /// let x = &mut [1, 2, 4];
394 /// let elem = x.get_unchecked_mut(1);
397 /// assert_eq!(x, &[1, 13, 4]);
399 #[stable(feature = "rust1", since = "1.0.0")]
401 pub unsafe fn get_unchecked_mut(&mut self, index
: usize) -> &mut T
{
402 core_slice
::SliceExt
::get_unchecked_mut(self, index
)
405 /// Returns an raw pointer to the slice's buffer
407 /// The caller must ensure that the slice outlives the pointer this
408 /// function returns, or else it will end up pointing to garbage.
410 /// Modifying the slice may cause its buffer to be reallocated, which
411 /// would also make any pointers to it invalid.
416 /// let x = &[1, 2, 4];
417 /// let x_ptr = x.as_ptr();
420 /// for i in 0..x.len() {
421 /// assert_eq!(x.get_unchecked(i), &*x_ptr.offset(i as isize));
425 #[stable(feature = "rust1", since = "1.0.0")]
427 pub fn as_ptr(&self) -> *const T
{
428 core_slice
::SliceExt
::as_ptr(self)
431 /// Returns an unsafe mutable pointer to the slice's buffer.
433 /// The caller must ensure that the slice outlives the pointer this
434 /// function returns, or else it will end up pointing to garbage.
436 /// Modifying the slice may cause its buffer to be reallocated, which
437 /// would also make any pointers to it invalid.
442 /// let x = &mut [1, 2, 4];
443 /// let x_ptr = x.as_mut_ptr();
446 /// for i in 0..x.len() {
447 /// *x_ptr.offset(i as isize) += 2;
450 /// assert_eq!(x, &[3, 4, 6]);
452 #[stable(feature = "rust1", since = "1.0.0")]
454 pub fn as_mut_ptr(&mut self) -> *mut T
{
455 core_slice
::SliceExt
::as_mut_ptr(self)
458 /// Swaps two elements in a slice.
462 /// * a - The index of the first element
463 /// * b - The index of the second element
467 /// Panics if `a` or `b` are out of bounds.
472 /// let mut v = ["a", "b", "c", "d"];
474 /// assert!(v == ["a", "d", "c", "b"]);
476 #[stable(feature = "rust1", since = "1.0.0")]
478 pub fn swap(&mut self, a
: usize, b
: usize) {
479 core_slice
::SliceExt
::swap(self, a
, b
)
482 /// Reverse the order of elements in a slice, in place.
487 /// let mut v = [1, 2, 3];
489 /// assert!(v == [3, 2, 1]);
491 #[stable(feature = "rust1", since = "1.0.0")]
493 pub fn reverse(&mut self) {
494 core_slice
::SliceExt
::reverse(self)
497 /// Returns an iterator over the slice.
502 /// let x = &[1, 2, 4];
503 /// let mut iterator = x.iter();
505 /// assert_eq!(iterator.next(), Some(&1));
506 /// assert_eq!(iterator.next(), Some(&2));
507 /// assert_eq!(iterator.next(), Some(&4));
508 /// assert_eq!(iterator.next(), None);
510 #[stable(feature = "rust1", since = "1.0.0")]
512 pub fn iter(&self) -> Iter
<T
> {
513 core_slice
::SliceExt
::iter(self)
516 /// Returns an iterator that allows modifying each value.
521 /// let x = &mut [1, 2, 4];
523 /// let iterator = x.iter_mut();
525 /// for elem in iterator {
529 /// assert_eq!(x, &[3, 4, 6]);
531 #[stable(feature = "rust1", since = "1.0.0")]
533 pub fn iter_mut(&mut self) -> IterMut
<T
> {
534 core_slice
::SliceExt
::iter_mut(self)
537 /// Returns an iterator over all contiguous windows of length
538 /// `size`. The windows overlap. If the slice is shorter than
539 /// `size`, the iterator returns no values.
543 /// Panics if `size` is 0.
548 /// let slice = ['r', 'u', 's', 't'];
549 /// let mut iter = slice.windows(2);
550 /// assert_eq!(iter.next().unwrap(), &['r', 'u']);
551 /// assert_eq!(iter.next().unwrap(), &['u', 's']);
552 /// assert_eq!(iter.next().unwrap(), &['s', 't']);
553 /// assert!(iter.next().is_none());
556 /// If the slice is shorter than `size`:
559 /// let slice = ['f', 'o', 'o'];
560 /// let mut iter = slice.windows(4);
561 /// assert!(iter.next().is_none());
563 #[stable(feature = "rust1", since = "1.0.0")]
565 pub fn windows(&self, size
: usize) -> Windows
<T
> {
566 core_slice
::SliceExt
::windows(self, size
)
569 /// Returns an iterator over `size` elements of the slice at a
570 /// time. The chunks are slices and do not overlap. If `size` does not divide the
571 /// length of the slice, then the last chunk will not have length
576 /// Panics if `size` is 0.
581 /// let slice = ['l', 'o', 'r', 'e', 'm'];
582 /// let mut iter = slice.chunks(2);
583 /// assert_eq!(iter.next().unwrap(), &['l', 'o']);
584 /// assert_eq!(iter.next().unwrap(), &['r', 'e']);
585 /// assert_eq!(iter.next().unwrap(), &['m']);
586 /// assert!(iter.next().is_none());
588 #[stable(feature = "rust1", since = "1.0.0")]
590 pub fn chunks(&self, size
: usize) -> Chunks
<T
> {
591 core_slice
::SliceExt
::chunks(self, size
)
594 /// Returns an iterator over `chunk_size` elements of the slice at a time.
595 /// The chunks are mutable slices, and do not overlap. If `chunk_size` does
596 /// not divide the length of the slice, then the last chunk will not
597 /// have length `chunk_size`.
601 /// Panics if `chunk_size` is 0.
606 /// let v = &mut [0, 0, 0, 0, 0];
607 /// let mut count = 1;
609 /// for chunk in v.chunks_mut(2) {
610 /// for elem in chunk.iter_mut() {
615 /// assert_eq!(v, &[1, 1, 2, 2, 3]);
617 #[stable(feature = "rust1", since = "1.0.0")]
619 pub fn chunks_mut(&mut self, chunk_size
: usize) -> ChunksMut
<T
> {
620 core_slice
::SliceExt
::chunks_mut(self, chunk_size
)
623 /// Divides one slice into two at an index.
625 /// The first will contain all indices from `[0, mid)` (excluding
626 /// the index `mid` itself) and the second will contain all
627 /// indices from `[mid, len)` (excluding the index `len` itself).
631 /// Panics if `mid > len`.
636 /// let v = [10, 40, 30, 20, 50];
637 /// let (v1, v2) = v.split_at(2);
638 /// assert_eq!([10, 40], v1);
639 /// assert_eq!([30, 20, 50], v2);
641 #[stable(feature = "rust1", since = "1.0.0")]
643 pub fn split_at(&self, mid
: usize) -> (&[T
], &[T
]) {
644 core_slice
::SliceExt
::split_at(self, mid
)
647 /// Divides one `&mut` into two at an index.
649 /// The first will contain all indices from `[0, mid)` (excluding
650 /// the index `mid` itself) and the second will contain all
651 /// indices from `[mid, len)` (excluding the index `len` itself).
655 /// Panics if `mid > len`.
660 /// let mut v = [1, 2, 3, 4, 5, 6];
662 /// // scoped to restrict the lifetime of the borrows
664 /// let (left, right) = v.split_at_mut(0);
665 /// assert!(left == []);
666 /// assert!(right == [1, 2, 3, 4, 5, 6]);
670 /// let (left, right) = v.split_at_mut(2);
671 /// assert!(left == [1, 2]);
672 /// assert!(right == [3, 4, 5, 6]);
676 /// let (left, right) = v.split_at_mut(6);
677 /// assert!(left == [1, 2, 3, 4, 5, 6]);
678 /// assert!(right == []);
681 #[stable(feature = "rust1", since = "1.0.0")]
683 pub fn split_at_mut(&mut self, mid
: usize) -> (&mut [T
], &mut [T
]) {
684 core_slice
::SliceExt
::split_at_mut(self, mid
)
687 /// Returns an iterator over subslices separated by elements that match
688 /// `pred`. The matched element is not contained in the subslices.
693 /// let slice = [10, 40, 33, 20];
694 /// let mut iter = slice.split(|num| num % 3 == 0);
696 /// assert_eq!(iter.next().unwrap(), &[10, 40]);
697 /// assert_eq!(iter.next().unwrap(), &[20]);
698 /// assert!(iter.next().is_none());
701 /// If the first element is matched, an empty slice will be the first item
702 /// returned by the iterator. Similarly, if the last element in the slice
703 /// is matched, an empty slice will be the last item returned by the
707 /// let slice = [10, 40, 33];
708 /// let mut iter = slice.split(|num| num % 3 == 0);
710 /// assert_eq!(iter.next().unwrap(), &[10, 40]);
711 /// assert_eq!(iter.next().unwrap(), &[]);
712 /// assert!(iter.next().is_none());
715 /// If two matched elements are directly adjacent, an empty slice will be
716 /// present between them:
719 /// let slice = [10, 6, 33, 20];
720 /// let mut iter = slice.split(|num| num % 3 == 0);
722 /// assert_eq!(iter.next().unwrap(), &[10]);
723 /// assert_eq!(iter.next().unwrap(), &[]);
724 /// assert_eq!(iter.next().unwrap(), &[20]);
725 /// assert!(iter.next().is_none());
727 #[stable(feature = "rust1", since = "1.0.0")]
729 pub fn split
<F
>(&self, pred
: F
) -> Split
<T
, F
>
730 where F
: FnMut(&T
) -> bool
732 core_slice
::SliceExt
::split(self, pred
)
735 /// Returns an iterator over mutable subslices separated by elements that
736 /// match `pred`. The matched element is not contained in the subslices.
741 /// let mut v = [10, 40, 30, 20, 60, 50];
743 /// for group in v.split_mut(|num| *num % 3 == 0) {
746 /// assert_eq!(v, [1, 40, 30, 1, 60, 1]);
748 #[stable(feature = "rust1", since = "1.0.0")]
750 pub fn split_mut
<F
>(&mut self, pred
: F
) -> SplitMut
<T
, F
>
751 where F
: FnMut(&T
) -> bool
753 core_slice
::SliceExt
::split_mut(self, pred
)
756 /// Returns an iterator over subslices separated by elements that match
757 /// `pred`, limited to returning at most `n` items. The matched element is
758 /// not contained in the subslices.
760 /// The last element returned, if any, will contain the remainder of the
765 /// Print the slice split once by numbers divisible by 3 (i.e. `[10, 40]`,
769 /// let v = [10, 40, 30, 20, 60, 50];
771 /// for group in v.splitn(2, |num| *num % 3 == 0) {
772 /// println!("{:?}", group);
775 #[stable(feature = "rust1", since = "1.0.0")]
777 pub fn splitn
<F
>(&self, n
: usize, pred
: F
) -> SplitN
<T
, F
>
778 where F
: FnMut(&T
) -> bool
780 core_slice
::SliceExt
::splitn(self, n
, pred
)
783 /// Returns an iterator over subslices separated by elements that match
784 /// `pred`, limited to returning at most `n` items. The matched element is
785 /// not contained in the subslices.
787 /// The last element returned, if any, will contain the remainder of the
793 /// let mut v = [10, 40, 30, 20, 60, 50];
795 /// for group in v.splitn_mut(2, |num| *num % 3 == 0) {
798 /// assert_eq!(v, [1, 40, 30, 1, 60, 50]);
800 #[stable(feature = "rust1", since = "1.0.0")]
802 pub fn splitn_mut
<F
>(&mut self, n
: usize, pred
: F
) -> SplitNMut
<T
, F
>
803 where F
: FnMut(&T
) -> bool
805 core_slice
::SliceExt
::splitn_mut(self, n
, pred
)
808 /// Returns an iterator over subslices separated by elements that match
809 /// `pred` limited to returning at most `n` items. This starts at the end of
810 /// the slice and works backwards. The matched element is not contained in
813 /// The last element returned, if any, will contain the remainder of the
818 /// Print the slice split once, starting from the end, by numbers divisible
819 /// by 3 (i.e. `[50]`, `[10, 40, 30, 20]`):
822 /// let v = [10, 40, 30, 20, 60, 50];
824 /// for group in v.rsplitn(2, |num| *num % 3 == 0) {
825 /// println!("{:?}", group);
828 #[stable(feature = "rust1", since = "1.0.0")]
830 pub fn rsplitn
<F
>(&self, n
: usize, pred
: F
) -> RSplitN
<T
, F
>
831 where F
: FnMut(&T
) -> bool
833 core_slice
::SliceExt
::rsplitn(self, n
, pred
)
836 /// Returns an iterator over subslices separated by elements that match
837 /// `pred` limited to returning at most `n` items. This starts at the end of
838 /// the slice and works backwards. The matched element is not contained in
841 /// The last element returned, if any, will contain the remainder of the
847 /// let mut s = [10, 40, 30, 20, 60, 50];
849 /// for group in s.rsplitn_mut(2, |num| *num % 3 == 0) {
852 /// assert_eq!(s, [1, 40, 30, 20, 60, 1]);
854 #[stable(feature = "rust1", since = "1.0.0")]
856 pub fn rsplitn_mut
<F
>(&mut self, n
: usize, pred
: F
) -> RSplitNMut
<T
, F
>
857 where F
: FnMut(&T
) -> bool
859 core_slice
::SliceExt
::rsplitn_mut(self, n
, pred
)
862 /// Returns true if the slice contains an element with the given value.
867 /// let v = [10, 40, 30];
868 /// assert!(v.contains(&30));
869 /// assert!(!v.contains(&50));
871 #[stable(feature = "rust1", since = "1.0.0")]
872 pub fn contains(&self, x
: &T
) -> bool
875 core_slice
::SliceExt
::contains(self, x
)
878 /// Returns true if `needle` is a prefix of the slice.
883 /// let v = [10, 40, 30];
884 /// assert!(v.starts_with(&[10]));
885 /// assert!(v.starts_with(&[10, 40]));
886 /// assert!(!v.starts_with(&[50]));
887 /// assert!(!v.starts_with(&[10, 50]));
889 #[stable(feature = "rust1", since = "1.0.0")]
890 pub fn starts_with(&self, needle
: &[T
]) -> bool
893 core_slice
::SliceExt
::starts_with(self, needle
)
896 /// Returns true if `needle` is a suffix of the slice.
901 /// let v = [10, 40, 30];
902 /// assert!(v.ends_with(&[30]));
903 /// assert!(v.ends_with(&[40, 30]));
904 /// assert!(!v.ends_with(&[50]));
905 /// assert!(!v.ends_with(&[50, 30]));
907 #[stable(feature = "rust1", since = "1.0.0")]
908 pub fn ends_with(&self, needle
: &[T
]) -> bool
911 core_slice
::SliceExt
::ends_with(self, needle
)
914 /// Binary search a sorted slice for a given element.
916 /// If the value is found then `Ok` is returned, containing the
917 /// index of the matching element; if the value is not found then
918 /// `Err` is returned, containing the index where a matching
919 /// element could be inserted while maintaining sorted order.
923 /// Looks up a series of four elements. The first is found, with a
924 /// uniquely determined position; the second and third are not
925 /// found; the fourth could match any position in `[1,4]`.
928 /// let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
930 /// assert_eq!(s.binary_search(&13), Ok(9));
931 /// assert_eq!(s.binary_search(&4), Err(7));
932 /// assert_eq!(s.binary_search(&100), Err(13));
933 /// let r = s.binary_search(&1);
934 /// assert!(match r { Ok(1...4) => true, _ => false, });
936 #[stable(feature = "rust1", since = "1.0.0")]
937 pub fn binary_search(&self, x
: &T
) -> Result
<usize, usize>
940 core_slice
::SliceExt
::binary_search(self, x
)
943 /// Binary search a sorted slice with a comparator function.
945 /// The comparator function should implement an order consistent
946 /// with the sort order of the underlying slice, returning an
947 /// order code that indicates whether its argument is `Less`,
948 /// `Equal` or `Greater` the desired target.
950 /// If a matching value is found then returns `Ok`, containing
951 /// the index for the matched element; if no match is found then
952 /// `Err` is returned, containing the index where a matching
953 /// element could be inserted while maintaining sorted order.
957 /// Looks up a series of four elements. The first is found, with a
958 /// uniquely determined position; the second and third are not
959 /// found; the fourth could match any position in `[1,4]`.
962 /// let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
965 /// assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Ok(9));
967 /// assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(7));
969 /// assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(13));
971 /// let r = s.binary_search_by(|probe| probe.cmp(&seek));
972 /// assert!(match r { Ok(1...4) => true, _ => false, });
974 #[stable(feature = "rust1", since = "1.0.0")]
976 pub fn binary_search_by
<'a
, F
>(&'a
self, f
: F
) -> Result
<usize, usize>
977 where F
: FnMut(&'a T
) -> Ordering
979 core_slice
::SliceExt
::binary_search_by(self, f
)
982 /// Binary search a sorted slice with a key extraction function.
984 /// Assumes that the slice is sorted by the key, for instance with
985 /// `sort_by_key` using the same key extraction function.
987 /// If a matching value is found then returns `Ok`, containing the
988 /// index for the matched element; if no match is found then `Err`
989 /// is returned, containing the index where a matching element could
990 /// be inserted while maintaining sorted order.
994 /// Looks up a series of four elements in a slice of pairs sorted by
995 /// their second elements. The first is found, with a uniquely
996 /// determined position; the second and third are not found; the
997 /// fourth could match any position in `[1,4]`.
1000 /// let s = [(0, 0), (2, 1), (4, 1), (5, 1), (3, 1),
1001 /// (1, 2), (2, 3), (4, 5), (5, 8), (3, 13),
1002 /// (1, 21), (2, 34), (4, 55)];
1004 /// assert_eq!(s.binary_search_by_key(&13, |&(a,b)| b), Ok(9));
1005 /// assert_eq!(s.binary_search_by_key(&4, |&(a,b)| b), Err(7));
1006 /// assert_eq!(s.binary_search_by_key(&100, |&(a,b)| b), Err(13));
1007 /// let r = s.binary_search_by_key(&1, |&(a,b)| b);
1008 /// assert!(match r { Ok(1...4) => true, _ => false, });
1010 #[stable(feature = "slice_binary_search_by_key", since = "1.10.0")]
1012 pub fn binary_search_by_key
<'a
, B
, F
>(&'a
self, b
: &B
, f
: F
) -> Result
<usize, usize>
1013 where F
: FnMut(&'a T
) -> B
,
1016 core_slice
::SliceExt
::binary_search_by_key(self, b
, f
)
1019 /// This is equivalent to `self.sort_by(|a, b| a.cmp(b))`.
1021 /// This sort is stable and `O(n log n)` worst-case but allocates
1022 /// approximately `2 * n` where `n` is the length of `self`.
1027 /// let mut v = [-5, 4, 1, -3, 2];
1030 /// assert!(v == [-5, -3, 1, 2, 4]);
1032 #[stable(feature = "rust1", since = "1.0.0")]
1034 pub fn sort(&mut self)
1037 self.sort_by(|a
, b
| a
.cmp(b
))
1040 /// Sorts the slice, in place, using `f` to extract a key by which to
1041 /// order the sort by.
1043 /// This sort is stable and `O(n log n)` worst-case but allocates
1044 /// approximately `2 * n`, where `n` is the length of `self`.
1049 /// let mut v = [-5i32, 4, 1, -3, 2];
1051 /// v.sort_by_key(|k| k.abs());
1052 /// assert!(v == [1, 2, -3, 4, -5]);
1054 #[stable(feature = "slice_sort_by_key", since = "1.7.0")]
1056 pub fn sort_by_key
<B
, F
>(&mut self, mut f
: F
)
1057 where F
: FnMut(&T
) -> B
, B
: Ord
1059 self.sort_by(|a
, b
| f(a
).cmp(&f(b
)))
1062 /// Sorts the slice, in place, using `compare` to compare
1065 /// This sort is stable and `O(n log n)` worst-case but allocates
1066 /// approximately `2 * n`, where `n` is the length of `self`.
1071 /// let mut v = [5, 4, 1, 3, 2];
1072 /// v.sort_by(|a, b| a.cmp(b));
1073 /// assert!(v == [1, 2, 3, 4, 5]);
1075 /// // reverse sorting
1076 /// v.sort_by(|a, b| b.cmp(a));
1077 /// assert!(v == [5, 4, 3, 2, 1]);
1079 #[stable(feature = "rust1", since = "1.0.0")]
1081 pub fn sort_by
<F
>(&mut self, compare
: F
)
1082 where F
: FnMut(&T
, &T
) -> Ordering
1084 merge_sort(self, compare
)
1087 /// Copies the elements from `src` into `self`.
1089 /// The length of `src` must be the same as `self`.
1093 /// This function will panic if the two slices have different lengths.
1098 /// let mut dst = [0, 0, 0];
1099 /// let src = [1, 2, 3];
1101 /// dst.clone_from_slice(&src);
1102 /// assert!(dst == [1, 2, 3]);
1104 #[stable(feature = "clone_from_slice", since = "1.7.0")]
1105 pub fn clone_from_slice(&mut self, src
: &[T
]) where T
: Clone
{
1106 core_slice
::SliceExt
::clone_from_slice(self, src
)
1109 /// Copies all elements from `src` into `self`, using a memcpy.
1111 /// The length of `src` must be the same as `self`.
1115 /// This function will panic if the two slices have different lengths.
1120 /// let mut dst = [0, 0, 0];
1121 /// let src = [1, 2, 3];
1123 /// dst.copy_from_slice(&src);
1124 /// assert_eq!(src, dst);
1126 #[stable(feature = "copy_from_slice", since = "1.9.0")]
1127 pub fn copy_from_slice(&mut self, src
: &[T
]) where T
: Copy
{
1128 core_slice
::SliceExt
::copy_from_slice(self, src
)
1132 /// Copies `self` into a new `Vec`.
1137 /// let s = [10, 40, 30];
1138 /// let x = s.to_vec();
1139 /// // Here, `s` and `x` can be modified independently.
1141 #[stable(feature = "rust1", since = "1.0.0")]
1143 pub fn to_vec(&self) -> Vec
<T
>
1146 // NB see hack module in this file
1150 /// Converts `self` into a vector without clones or allocation.
1155 /// let s: Box<[i32]> = Box::new([10, 40, 30]);
1156 /// let x = s.into_vec();
1157 /// // `s` cannot be used anymore because it has been converted into `x`.
1159 /// assert_eq!(x, vec!(10, 40, 30));
1161 #[stable(feature = "rust1", since = "1.0.0")]
1163 pub fn into_vec(self: Box
<Self>) -> Vec
<T
> {
1164 // NB see hack module in this file
1165 hack
::into_vec(self)
1169 ////////////////////////////////////////////////////////////////////////////////
1170 // Extension traits for slices over specific kinds of data
1171 ////////////////////////////////////////////////////////////////////////////////
1172 #[unstable(feature = "slice_concat_ext",
1173 reason
= "trait should not have to exist",
1175 /// An extension trait for concatenating slices
1176 pub trait SliceConcatExt
<T
: ?Sized
> {
1177 #[unstable(feature = "slice_concat_ext",
1178 reason
= "trait should not have to exist",
1180 /// The resulting type after concatenation
1183 /// Flattens a slice of `T` into a single value `Self::Output`.
1188 /// assert_eq!(["hello", "world"].concat(), "helloworld");
1190 #[stable(feature = "rust1", since = "1.0.0")]
1191 fn concat(&self) -> Self::Output
;
1193 /// Flattens a slice of `T` into a single value `Self::Output`, placing a
1194 /// given separator between each.
1199 /// assert_eq!(["hello", "world"].join(" "), "hello world");
1201 #[stable(feature = "rename_connect_to_join", since = "1.3.0")]
1202 fn join(&self, sep
: &T
) -> Self::Output
;
1204 #[stable(feature = "rust1", since = "1.0.0")]
1205 #[rustc_deprecated(since = "1.3.0", reason = "renamed to join")]
1206 fn connect(&self, sep
: &T
) -> Self::Output
;
1209 #[unstable(feature = "slice_concat_ext",
1210 reason
= "trait should not have to exist",
1212 impl<T
: Clone
, V
: Borrow
<[T
]>> SliceConcatExt
<T
> for [V
] {
1213 type Output
= Vec
<T
>;
1215 fn concat(&self) -> Vec
<T
> {
1216 let size
= self.iter().fold(0, |acc
, v
| acc
+ v
.borrow().len());
1217 let mut result
= Vec
::with_capacity(size
);
1219 result
.extend_from_slice(v
.borrow())
1224 fn join(&self, sep
: &T
) -> Vec
<T
> {
1225 let size
= self.iter().fold(0, |acc
, v
| acc
+ v
.borrow().len());
1226 let mut result
= Vec
::with_capacity(size
+ self.len());
1227 let mut first
= true;
1232 result
.push(sep
.clone())
1234 result
.extend_from_slice(v
.borrow())
1239 fn connect(&self, sep
: &T
) -> Vec
<T
> {
1244 ////////////////////////////////////////////////////////////////////////////////
1245 // Standard trait implementations for slices
1246 ////////////////////////////////////////////////////////////////////////////////
1248 #[stable(feature = "rust1", since = "1.0.0")]
1249 impl<T
> Borrow
<[T
]> for Vec
<T
> {
1250 fn borrow(&self) -> &[T
] {
1255 #[stable(feature = "rust1", since = "1.0.0")]
1256 impl<T
> BorrowMut
<[T
]> for Vec
<T
> {
1257 fn borrow_mut(&mut self) -> &mut [T
] {
1262 #[stable(feature = "rust1", since = "1.0.0")]
1263 impl<T
: Clone
> ToOwned
for [T
] {
1264 type Owned
= Vec
<T
>;
1266 fn to_owned(&self) -> Vec
<T
> {
1270 // HACK(japaric): with cfg(test) the inherent `[T]::to_vec`, which is required for this method
1271 // definition, is not available. Since we don't require this method for testing purposes, I'll
1273 // NB see the slice::hack module in slice.rs for more information
1275 fn to_owned(&self) -> Vec
<T
> {
1276 panic
!("not available with cfg(test)")
1280 ////////////////////////////////////////////////////////////////////////////////
1282 ////////////////////////////////////////////////////////////////////////////////
1284 fn insertion_sort
<T
, F
>(v
: &mut [T
], mut compare
: F
)
1285 where F
: FnMut(&T
, &T
) -> Ordering
1287 let len
= v
.len() as isize;
1288 let buf_v
= v
.as_mut_ptr();
1292 // j satisfies: 0 <= j <= i;
1295 // `i` is in bounds.
1296 let read_ptr
= buf_v
.offset(i
) as *const T
;
1298 // find where to insert, we need to do strict <,
1299 // rather than <=, to maintain stability.
1301 // 0 <= j - 1 < len, so .offset(j - 1) is in bounds.
1302 while j
> 0 && compare(&*read_ptr
, &*buf_v
.offset(j
- 1)) == Less
{
1306 // shift everything to the right, to make space to
1307 // insert this value.
1309 // j + 1 could be `len` (for the last `i`), but in
1310 // that case, `i == j` so we don't copy. The
1311 // `.offset(j)` is always in bounds.
1314 let tmp
= ptr
::read(read_ptr
);
1315 ptr
::copy(&*buf_v
.offset(j
), buf_v
.offset(j
+ 1), (i
- j
) as usize);
1316 ptr
::copy_nonoverlapping(&tmp
, buf_v
.offset(j
), 1);
1323 fn merge_sort
<T
, F
>(v
: &mut [T
], mut compare
: F
)
1324 where F
: FnMut(&T
, &T
) -> Ordering
1326 // warning: this wildly uses unsafe.
1327 const BASE_INSERTION
: usize = 32;
1328 const LARGE_INSERTION
: usize = 16;
1330 // FIXME #12092: smaller insertion runs seems to make sorting
1331 // vectors of large elements a little faster on some platforms,
1332 // but hasn't been tested/tuned extensively
1333 let insertion
= if size_of
::<T
>() <= 16 {
1341 // short vectors get sorted in-place via insertion sort to avoid allocations
1342 if len
<= insertion
{
1343 insertion_sort(v
, compare
);
1347 // allocate some memory to use as scratch memory, we keep the
1348 // length 0 so we can keep shallow copies of the contents of `v`
1349 // without risking the dtors running on an object twice if
1350 // `compare` panics.
1351 let mut working_space
= Vec
::with_capacity(2 * len
);
1352 // these both are buffers of length `len`.
1353 let mut buf_dat
= working_space
.as_mut_ptr();
1354 let mut buf_tmp
= unsafe { buf_dat.offset(len as isize) }
;
1357 let buf_v
= v
.as_ptr();
1359 // step 1. sort short runs with insertion sort. This takes the
1360 // values from `v` and sorts them into `buf_dat`, leaving that
1361 // with sorted runs of length INSERTION.
1363 // We could hardcode the sorting comparisons here, and we could
1364 // manipulate/step the pointers themselves, rather than repeatedly
1366 for start
in (0..len
).step_by(insertion
) {
1367 // start <= i < len;
1368 for i
in start
..cmp
::min(start
+ insertion
, len
) {
1369 // j satisfies: start <= j <= i;
1370 let mut j
= i
as isize;
1372 // `i` is in bounds.
1373 let read_ptr
= buf_v
.offset(i
as isize);
1375 // find where to insert, we need to do strict <,
1376 // rather than <=, to maintain stability.
1378 // start <= j - 1 < len, so .offset(j - 1) is in
1380 while j
> start
as isize && compare(&*read_ptr
, &*buf_dat
.offset(j
- 1)) == Less
{
1384 // shift everything to the right, to make space to
1385 // insert this value.
1387 // j + 1 could be `len` (for the last `i`), but in
1388 // that case, `i == j` so we don't copy. The
1389 // `.offset(j)` is always in bounds.
1390 ptr
::copy(&*buf_dat
.offset(j
), buf_dat
.offset(j
+ 1), i
- j
as usize);
1391 ptr
::copy_nonoverlapping(read_ptr
, buf_dat
.offset(j
), 1);
1396 // step 2. merge the sorted runs.
1397 let mut width
= insertion
;
1399 // merge the sorted runs of length `width` in `buf_dat` two at
1400 // a time, placing the result in `buf_tmp`.
1402 // 0 <= start <= len.
1403 for start
in (0..len
).step_by(2 * width
) {
1404 // manipulate pointers directly for speed (rather than
1405 // using a `for` loop with `range` and `.offset` inside
1408 // the end of the first run & start of the
1409 // second. Offset of `len` is defined, since this is
1410 // precisely one byte past the end of the object.
1411 let right_start
= buf_dat
.offset(cmp
::min(start
+ width
, len
) as isize);
1412 // end of the second. Similar reasoning to the above re safety.
1413 let right_end_idx
= cmp
::min(start
+ 2 * width
, len
);
1414 let right_end
= buf_dat
.offset(right_end_idx
as isize);
1416 // the pointers to the elements under consideration
1417 // from the two runs.
1419 // both of these are in bounds.
1420 let mut left
= buf_dat
.offset(start
as isize);
1421 let mut right
= right_start
;
1423 // where we're putting the results, it is a run of
1424 // length `2*width`, so we step it once for each step
1425 // of either `left` or `right`. `buf_tmp` has length
1426 // `len`, so these are in bounds.
1427 let mut out
= buf_tmp
.offset(start
as isize);
1428 let out_end
= buf_tmp
.offset(right_end_idx
as isize);
1430 // If left[last] <= right[0], they are already in order:
1431 // fast-forward the left side (the right side is handled
1433 // If `right` is not empty then left is not empty, and
1434 // the offsets are in bounds.
1435 if right
!= right_end
&& compare(&*right
.offset(-1), &*right
) != Greater
{
1436 let elems
= (right_start
as usize - left
as usize) / mem
::size_of
::<T
>();
1437 ptr
::copy_nonoverlapping(&*left
, out
, elems
);
1438 out
= out
.offset(elems
as isize);
1442 while out
< out_end
{
1443 // Either the left or the right run are exhausted,
1444 // so just copy the remainder from the other run
1445 // and move on; this gives a huge speed-up (order
1446 // of 25%) for mostly sorted vectors (the best
1448 if left
== right_start
{
1449 // the number remaining in this run.
1450 let elems
= (right_end
as usize - right
as usize) / mem
::size_of
::<T
>();
1451 ptr
::copy_nonoverlapping(&*right
, out
, elems
);
1453 } else if right
== right_end
{
1454 let elems
= (right_start
as usize - left
as usize) / mem
::size_of
::<T
>();
1455 ptr
::copy_nonoverlapping(&*left
, out
, elems
);
1459 // check which side is smaller, and that's the
1460 // next element for the new run.
1462 // `left < right_start` and `right < right_end`,
1463 // so these are valid.
1464 let to_copy
= if compare(&*left
, &*right
) == Greater
{
1469 ptr
::copy_nonoverlapping(&*to_copy
, out
, 1);
1475 mem
::swap(&mut buf_dat
, &mut buf_tmp
);
1480 // write the result to `v` in one go, so that there are never two copies
1481 // of the same object in `v`.
1483 ptr
::copy_nonoverlapping(&*buf_dat
, v
.as_mut_ptr(), len
);
1486 // increment the pointer, returning the old pointer.
1488 unsafe fn step
<T
>(ptr
: &mut *mut T
) -> *mut T
{
1490 *ptr
= ptr
.offset(1);