1 // Copyright 2012-2014 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 `std::slice`.
15 #![stable(feature = "rust1", since = "1.0.0")]
17 // How this module is organized.
19 // The library infrastructure for slices is fairly messy. There's
20 // a lot of stuff defined here. Let's keep it clean.
22 // Since slices don't support inherent methods; all operations
23 // on them are defined on traits, which are then reexported from
24 // the prelude for convenience. So there are a lot of traits here.
26 // The layout of this file is thus:
28 // * Slice-specific 'extension' traits and their implementations. This
29 // is where most of the slice API resides.
30 // * Implementations of a few common traits with important slice ops.
31 // * Definitions of a bunch of iterators.
33 // * The `raw` and `bytes` submodules.
34 // * Boilerplate trait implementations.
37 use cmp::{Ordering, PartialEq, PartialOrd, Eq, Ord};
38 use cmp::Ordering::{Less, Equal, Greater};
41 use intrinsics::assume;
43 use ops::{FnMut, self, Index};
46 use option::Option::{None, Some};
48 use result::Result::{Ok, Err};
51 use marker::{Copy, Send, Sync, self};
53 // Avoid conflicts with *both* the Slice trait (buggy) and the `slice::raw` module.
54 use raw::Slice as RawSlice;
61 /// Extension methods for slices.
62 #[unstable(feature = "core_slice_ext",
63 reason = "stable interface provided by `impl [T]` in later crates",
65 #[allow(missing_docs)] // documented elsewhere
69 #[stable(feature = "core", since = "1.6.0")]
70 fn split_at(&self, mid: usize) -> (&[Self::Item], &[Self::Item]);
71 #[stable(feature = "core", since = "1.6.0")]
72 fn iter(&self) -> Iter<Self::Item>;
73 #[stable(feature = "core", since = "1.6.0")]
74 fn split<P>(&self, pred: P) -> Split<Self::Item, P>
75 where P: FnMut(&Self::Item) -> bool;
76 #[stable(feature = "core", since = "1.6.0")]
77 fn splitn<P>(&self, n: usize, pred: P) -> SplitN<Self::Item, P>
78 where P: FnMut(&Self::Item) -> bool;
79 #[stable(feature = "core", since = "1.6.0")]
80 fn rsplitn<P>(&self, n: usize, pred: P) -> RSplitN<Self::Item, P>
81 where P: FnMut(&Self::Item) -> bool;
82 #[stable(feature = "core", since = "1.6.0")]
83 fn windows(&self, size: usize) -> Windows<Self::Item>;
84 #[stable(feature = "core", since = "1.6.0")]
85 fn chunks(&self, size: usize) -> Chunks<Self::Item>;
86 #[stable(feature = "core", since = "1.6.0")]
87 fn get(&self, index: usize) -> Option<&Self::Item>;
88 #[stable(feature = "core", since = "1.6.0")]
89 fn first(&self) -> Option<&Self::Item>;
90 #[stable(feature = "core", since = "1.6.0")]
91 fn split_first(&self) -> Option<(&Self::Item, &[Self::Item])>;
92 #[stable(feature = "core", since = "1.6.0")]
93 fn split_last(&self) -> Option<(&Self::Item, &[Self::Item])>;
94 #[stable(feature = "core", since = "1.6.0")]
95 fn last(&self) -> Option<&Self::Item>;
96 #[stable(feature = "core", since = "1.6.0")]
97 unsafe fn get_unchecked(&self, index: usize) -> &Self::Item;
98 #[stable(feature = "core", since = "1.6.0")]
99 fn as_ptr(&self) -> *const Self::Item;
100 #[stable(feature = "core", since = "1.6.0")]
101 fn binary_search(&self, x: &Self::Item) -> Result<usize, usize>
102 where Self::Item: Ord;
103 #[stable(feature = "core", since = "1.6.0")]
104 fn binary_search_by<F>(&self, f: F) -> Result<usize, usize>
105 where F: FnMut(&Self::Item) -> Ordering;
106 #[stable(feature = "core", since = "1.6.0")]
107 fn len(&self) -> usize;
108 #[stable(feature = "core", since = "1.6.0")]
109 fn is_empty(&self) -> bool { self.len() == 0 }
110 #[stable(feature = "core", since = "1.6.0")]
111 fn get_mut(&mut self, index: usize) -> Option<&mut Self::Item>;
112 #[stable(feature = "core", since = "1.6.0")]
113 fn iter_mut(&mut self) -> IterMut<Self::Item>;
114 #[stable(feature = "core", since = "1.6.0")]
115 fn first_mut(&mut self) -> Option<&mut Self::Item>;
116 #[stable(feature = "core", since = "1.6.0")]
117 fn split_first_mut(&mut self) -> Option<(&mut Self::Item, &mut [Self::Item])>;
118 #[stable(feature = "core", since = "1.6.0")]
119 fn split_last_mut(&mut self) -> Option<(&mut Self::Item, &mut [Self::Item])>;
120 #[stable(feature = "core", since = "1.6.0")]
121 fn last_mut(&mut self) -> Option<&mut Self::Item>;
122 #[stable(feature = "core", since = "1.6.0")]
123 fn split_mut<P>(&mut self, pred: P) -> SplitMut<Self::Item, P>
124 where P: FnMut(&Self::Item) -> bool;
125 #[stable(feature = "core", since = "1.6.0")]
126 fn splitn_mut<P>(&mut self, n: usize, pred: P) -> SplitNMut<Self::Item, P>
127 where P: FnMut(&Self::Item) -> bool;
128 #[stable(feature = "core", since = "1.6.0")]
129 fn rsplitn_mut<P>(&mut self, n: usize, pred: P) -> RSplitNMut<Self::Item, P>
130 where P: FnMut(&Self::Item) -> bool;
131 #[stable(feature = "core", since = "1.6.0")]
132 fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<Self::Item>;
133 #[stable(feature = "core", since = "1.6.0")]
134 fn swap(&mut self, a: usize, b: usize);
135 #[stable(feature = "core", since = "1.6.0")]
136 fn split_at_mut(&mut self, mid: usize) -> (&mut [Self::Item], &mut [Self::Item]);
137 #[stable(feature = "core", since = "1.6.0")]
138 fn reverse(&mut self);
139 #[stable(feature = "core", since = "1.6.0")]
140 unsafe fn get_unchecked_mut(&mut self, index: usize) -> &mut Self::Item;
141 #[stable(feature = "core", since = "1.6.0")]
142 fn as_mut_ptr(&mut self) -> *mut Self::Item;
144 #[stable(feature = "core", since = "1.6.0")]
145 fn contains(&self, x: &Self::Item) -> bool where Self::Item: PartialEq;
147 #[stable(feature = "core", since = "1.6.0")]
148 fn starts_with(&self, needle: &[Self::Item]) -> bool where Self::Item: PartialEq;
150 #[stable(feature = "core", since = "1.6.0")]
151 fn ends_with(&self, needle: &[Self::Item]) -> bool where Self::Item: PartialEq;
153 #[stable(feature = "clone_from_slice", since = "1.7.0")]
154 fn clone_from_slice(&mut self, &[Self::Item]) where Self::Item: Clone;
155 #[unstable(feature = "copy_from_slice", issue = "31755")]
156 fn copy_from_slice(&mut self, src: &[Self::Item]) where Self::Item: Copy;
159 // Use macros to be generic over const/mut
160 macro_rules! slice_offset {
161 ($ptr:expr, $by:expr) => {{
163 if size_from_ptr(ptr) == 0 {
164 ::intrinsics::arith_offset(ptr as *mut i8, $by) as *mut _
171 macro_rules! slice_ref {
174 if size_from_ptr(ptr) == 0 {
175 // Use a non-null pointer value
183 #[unstable(feature = "core_slice_ext",
184 reason = "stable interface provided by `impl [T]` in later crates",
186 impl<T> SliceExt for [T] {
190 fn split_at(&self, mid: usize) -> (&[T], &[T]) {
191 (&self[..mid], &self[mid..])
195 fn iter(&self) -> Iter<T> {
197 let p = if mem::size_of::<T>() == 0 {
200 let p = self.as_ptr();
201 assume(!p.is_null());
207 end: slice_offset!(p, self.len() as isize),
208 _marker: marker::PhantomData
214 fn split<P>(&self, pred: P) -> Split<T, P> where P: FnMut(&T) -> bool {
223 fn splitn<P>(&self, n: usize, pred: P) -> SplitN<T, P> where
224 P: FnMut(&T) -> bool,
227 inner: GenericSplitN {
228 iter: self.split(pred),
236 fn rsplitn<P>(&self, n: usize, pred: P) -> RSplitN<T, P> where
237 P: FnMut(&T) -> bool,
240 inner: GenericSplitN {
241 iter: self.split(pred),
249 fn windows(&self, size: usize) -> Windows<T> {
251 Windows { v: self, size: size }
255 fn chunks(&self, size: usize) -> Chunks<T> {
257 Chunks { v: self, size: size }
261 fn get(&self, index: usize) -> Option<&T> {
262 if index < self.len() { Some(&self[index]) } else { None }
266 fn first(&self) -> Option<&T> {
267 if self.is_empty() { None } else { Some(&self[0]) }
271 fn split_first(&self) -> Option<(&T, &[T])> {
272 if self.is_empty() { None } else { Some((&self[0], &self[1..])) }
276 fn split_last(&self) -> Option<(&T, &[T])> {
277 let len = self.len();
278 if len == 0 { None } else { Some((&self[len - 1], &self[..(len - 1)])) }
282 fn last(&self) -> Option<&T> {
283 if self.is_empty() { None } else { Some(&self[self.len() - 1]) }
287 unsafe fn get_unchecked(&self, index: usize) -> &T {
288 &*(self.repr().data.offset(index as isize))
292 fn as_ptr(&self) -> *const T {
296 fn binary_search_by<F>(&self, mut f: F) -> Result<usize, usize> where
297 F: FnMut(&T) -> Ordering
299 let mut base = 0usize;
303 let (head, tail) = s.split_at(s.len() >> 1);
309 base += head.len() + 1;
313 Equal => return Ok(base + head.len()),
319 fn len(&self) -> usize { self.repr().len }
322 fn get_mut(&mut self, index: usize) -> Option<&mut T> {
323 if index < self.len() { Some(&mut self[index]) } else { None }
327 fn split_at_mut(&mut self, mid: usize) -> (&mut [T], &mut [T]) {
328 let len = self.len();
329 let ptr = self.as_mut_ptr();
334 (from_raw_parts_mut(ptr, mid),
335 from_raw_parts_mut(ptr.offset(mid as isize), len - mid))
340 fn iter_mut(&mut self) -> IterMut<T> {
342 let p = if mem::size_of::<T>() == 0 {
345 let p = self.as_mut_ptr();
346 assume(!p.is_null());
352 end: slice_offset!(p, self.len() as isize),
353 _marker: marker::PhantomData
359 fn last_mut(&mut self) -> Option<&mut T> {
360 let len = self.len();
361 if len == 0 { return None; }
362 Some(&mut self[len - 1])
366 fn first_mut(&mut self) -> Option<&mut T> {
367 if self.is_empty() { None } else { Some(&mut self[0]) }
371 fn split_first_mut(&mut self) -> Option<(&mut T, &mut [T])> {
372 if self.is_empty() { None } else {
373 let split = self.split_at_mut(1);
374 Some((&mut split.0[0], split.1))
379 fn split_last_mut(&mut self) -> Option<(&mut T, &mut [T])> {
380 let len = self.len();
381 if len == 0 { None } else {
382 let split = self.split_at_mut(len - 1);
383 Some((&mut split.1[0], split.0))
388 fn split_mut<P>(&mut self, pred: P) -> SplitMut<T, P> where P: FnMut(&T) -> bool {
389 SplitMut { v: self, pred: pred, finished: false }
393 fn splitn_mut<P>(&mut self, n: usize, pred: P) -> SplitNMut<T, P> where
397 inner: GenericSplitN {
398 iter: self.split_mut(pred),
406 fn rsplitn_mut<P>(&mut self, n: usize, pred: P) -> RSplitNMut<T, P> where
407 P: FnMut(&T) -> bool,
410 inner: GenericSplitN {
411 iter: self.split_mut(pred),
419 fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<T> {
420 assert!(chunk_size > 0);
421 ChunksMut { v: self, chunk_size: chunk_size }
425 fn swap(&mut self, a: usize, b: usize) {
427 // Can't take two mutable loans from one vector, so instead just cast
428 // them to their raw pointers to do the swap
429 let pa: *mut T = &mut self[a];
430 let pb: *mut T = &mut self[b];
435 fn reverse(&mut self) {
436 let mut i: usize = 0;
439 // Unsafe swap to avoid the bounds check in safe swap.
441 let pa: *mut T = self.get_unchecked_mut(i);
442 let pb: *mut T = self.get_unchecked_mut(ln - i - 1);
450 unsafe fn get_unchecked_mut(&mut self, index: usize) -> &mut T {
451 &mut *(self.repr().data as *mut T).offset(index as isize)
455 fn as_mut_ptr(&mut self) -> *mut T {
456 self.repr().data as *mut T
460 fn contains(&self, x: &T) -> bool where T: PartialEq {
461 self.iter().any(|elt| *x == *elt)
465 fn starts_with(&self, needle: &[T]) -> bool where T: PartialEq {
466 let n = needle.len();
467 self.len() >= n && needle == &self[..n]
471 fn ends_with(&self, needle: &[T]) -> bool where T: PartialEq {
472 let (m, n) = (self.len(), needle.len());
473 m >= n && needle == &self[m-n..]
476 fn binary_search(&self, x: &T) -> Result<usize, usize> where T: Ord {
477 self.binary_search_by(|p| p.cmp(x))
481 fn clone_from_slice(&mut self, src: &[T]) where T: Clone {
482 assert!(self.len() == src.len(),
483 "destination and source slices have different lengths");
484 // NOTE: We need to explicitly slice them to the same length
485 // for bounds checking to be elided, and the optimizer will
486 // generate memcpy for simple cases (for example T = u8).
487 let len = self.len();
488 let src = &src[..len];
490 self[i].clone_from(&src[i]);
495 fn copy_from_slice(&mut self, src: &[T]) where T: Copy {
496 assert!(self.len() == src.len(),
497 "destination and source slices have different lengths");
499 ptr::copy_nonoverlapping(
500 src.as_ptr(), self.as_mut_ptr(), self.len());
505 #[stable(feature = "rust1", since = "1.0.0")]
506 impl<T> ops::Index<usize> for [T] {
509 fn index(&self, index: usize) -> &T {
510 assert!(index < self.len());
511 unsafe { self.get_unchecked(index) }
515 #[stable(feature = "rust1", since = "1.0.0")]
516 impl<T> ops::IndexMut<usize> for [T] {
518 fn index_mut(&mut self, index: usize) -> &mut T {
519 assert!(index < self.len());
520 unsafe { self.get_unchecked_mut(index) }
526 fn slice_index_len_fail(index: usize, len: usize) -> ! {
527 panic!("index {} out of range for slice of length {}", index, len);
532 fn slice_index_order_fail(index: usize, end: usize) -> ! {
533 panic!("slice index starts at {} but ends at {}", index, end);
536 // FIXME implement indexing with inclusive ranges
538 #[stable(feature = "rust1", since = "1.0.0")]
539 impl<T> ops::Index<ops::Range<usize>> for [T] {
543 fn index(&self, index: ops::Range<usize>) -> &[T] {
544 if index.start > index.end {
545 slice_index_order_fail(index.start, index.end);
546 } else if index.end > self.len() {
547 slice_index_len_fail(index.end, self.len());
551 self.as_ptr().offset(index.start as isize),
552 index.end - index.start
557 #[stable(feature = "rust1", since = "1.0.0")]
558 impl<T> ops::Index<ops::RangeTo<usize>> for [T] {
562 fn index(&self, index: ops::RangeTo<usize>) -> &[T] {
563 self.index(0 .. index.end)
566 #[stable(feature = "rust1", since = "1.0.0")]
567 impl<T> ops::Index<ops::RangeFrom<usize>> for [T] {
571 fn index(&self, index: ops::RangeFrom<usize>) -> &[T] {
572 self.index(index.start .. self.len())
575 #[stable(feature = "rust1", since = "1.0.0")]
576 impl<T> ops::Index<RangeFull> for [T] {
580 fn index(&self, _index: RangeFull) -> &[T] {
585 #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
586 impl<T> ops::Index<ops::RangeInclusive<usize>> for [T] {
590 fn index(&self, index: ops::RangeInclusive<usize>) -> &[T] {
592 ops::RangeInclusive::Empty { .. } => &[],
593 ops::RangeInclusive::NonEmpty { end, .. } if end == usize::max_value() =>
594 panic!("attempted to index slice up to maximum usize"),
595 ops::RangeInclusive::NonEmpty { start, end } =>
596 self.index(start .. end+1)
600 #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
601 impl<T> ops::Index<ops::RangeToInclusive<usize>> for [T] {
605 fn index(&self, index: ops::RangeToInclusive<usize>) -> &[T] {
606 // SNAP 4d3eebf change this to `0...index.end`
607 self.index(ops::RangeInclusive::NonEmpty { start: 0, end: index.end })
611 #[stable(feature = "rust1", since = "1.0.0")]
612 impl<T> ops::IndexMut<ops::Range<usize>> for [T] {
614 fn index_mut(&mut self, index: ops::Range<usize>) -> &mut [T] {
615 if index.start > index.end {
616 slice_index_order_fail(index.start, index.end);
617 } else if index.end > self.len() {
618 slice_index_len_fail(index.end, self.len());
622 self.as_mut_ptr().offset(index.start as isize),
623 index.end - index.start
628 #[stable(feature = "rust1", since = "1.0.0")]
629 impl<T> ops::IndexMut<ops::RangeTo<usize>> for [T] {
631 fn index_mut(&mut self, index: ops::RangeTo<usize>) -> &mut [T] {
632 self.index_mut(0 .. index.end)
635 #[stable(feature = "rust1", since = "1.0.0")]
636 impl<T> ops::IndexMut<ops::RangeFrom<usize>> for [T] {
638 fn index_mut(&mut self, index: ops::RangeFrom<usize>) -> &mut [T] {
639 let len = self.len();
640 self.index_mut(index.start .. len)
643 #[stable(feature = "rust1", since = "1.0.0")]
644 impl<T> ops::IndexMut<RangeFull> for [T] {
646 fn index_mut(&mut self, _index: RangeFull) -> &mut [T] {
651 #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
652 impl<T> ops::IndexMut<ops::RangeInclusive<usize>> for [T] {
654 fn index_mut(&mut self, index: ops::RangeInclusive<usize>) -> &mut [T] {
656 ops::RangeInclusive::Empty { .. } => &mut [],
657 ops::RangeInclusive::NonEmpty { end, .. } if end == usize::max_value() =>
658 panic!("attempted to index slice up to maximum usize"),
659 ops::RangeInclusive::NonEmpty { start, end } =>
660 self.index_mut(start .. end+1)
664 #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
665 impl<T> ops::IndexMut<ops::RangeToInclusive<usize>> for [T] {
667 fn index_mut(&mut self, index: ops::RangeToInclusive<usize>) -> &mut [T] {
668 // SNAP 4d3eebf change this to `0...index.end`
669 self.index_mut(ops::RangeInclusive::NonEmpty { start: 0, end: index.end })
673 ////////////////////////////////////////////////////////////////////////////////
675 ////////////////////////////////////////////////////////////////////////////////
677 #[stable(feature = "rust1", since = "1.0.0")]
678 impl<'a, T> Default for &'a [T] {
679 fn default() -> &'a [T] { &[] }
682 #[stable(feature = "mut_slice_default", since = "1.5.0")]
683 impl<'a, T> Default for &'a mut [T] {
684 fn default() -> &'a mut [T] { &mut [] }
691 #[stable(feature = "rust1", since = "1.0.0")]
692 impl<'a, T> IntoIterator for &'a [T] {
694 type IntoIter = Iter<'a, T>;
696 fn into_iter(self) -> Iter<'a, T> {
701 #[stable(feature = "rust1", since = "1.0.0")]
702 impl<'a, T> IntoIterator for &'a mut [T] {
703 type Item = &'a mut T;
704 type IntoIter = IterMut<'a, T>;
706 fn into_iter(self) -> IterMut<'a, T> {
712 fn size_from_ptr<T>(_: *const T) -> usize {
716 // The shared definition of the `Iter` and `IterMut` iterators
717 macro_rules! iterator {
718 (struct $name:ident -> $ptr:ty, $elem:ty) => {
719 #[stable(feature = "rust1", since = "1.0.0")]
720 impl<'a, T> Iterator for $name<'a, T> {
724 fn next(&mut self) -> Option<$elem> {
725 // could be implemented with slices, but this avoids bounds checks
727 if mem::size_of::<T>() != 0 {
728 assume(!self.ptr.is_null());
729 assume(!self.end.is_null());
731 if self.ptr == self.end {
735 self.ptr = slice_offset!(self.ptr, 1);
736 Some(slice_ref!(old))
742 fn size_hint(&self) -> (usize, Option<usize>) {
743 let diff = (self.end as usize).wrapping_sub(self.ptr as usize);
744 let size = mem::size_of::<T>();
745 let exact = diff / (if size == 0 {1} else {size});
750 fn count(self) -> usize {
755 fn nth(&mut self, n: usize) -> Option<$elem> {
756 // Call helper method. Can't put the definition here because mut versus const.
761 fn last(mut self) -> Option<$elem> {
766 #[stable(feature = "rust1", since = "1.0.0")]
767 impl<'a, T> DoubleEndedIterator for $name<'a, T> {
769 fn next_back(&mut self) -> Option<$elem> {
770 // could be implemented with slices, but this avoids bounds checks
772 if mem::size_of::<T>() != 0 {
773 assume(!self.ptr.is_null());
774 assume(!self.end.is_null());
776 if self.end == self.ptr {
779 self.end = slice_offset!(self.end, -1);
780 Some(slice_ref!(self.end))
788 macro_rules! make_slice {
789 ($start: expr, $end: expr) => {{
791 let diff = ($end as usize).wrapping_sub(start as usize);
792 if size_from_ptr(start) == 0 {
793 // use a non-null pointer value
794 unsafe { from_raw_parts(1 as *const _, diff) }
796 let len = diff / size_from_ptr(start);
797 unsafe { from_raw_parts(start, len) }
802 macro_rules! make_mut_slice {
803 ($start: expr, $end: expr) => {{
805 let diff = ($end as usize).wrapping_sub(start as usize);
806 if size_from_ptr(start) == 0 {
807 // use a non-null pointer value
808 unsafe { from_raw_parts_mut(1 as *mut _, diff) }
810 let len = diff / size_from_ptr(start);
811 unsafe { from_raw_parts_mut(start, len) }
816 /// Immutable slice iterator
817 #[stable(feature = "rust1", since = "1.0.0")]
818 pub struct Iter<'a, T: 'a> {
821 _marker: marker::PhantomData<&'a T>,
824 #[stable(feature = "rust1", since = "1.0.0")]
825 unsafe impl<'a, T: Sync> Sync for Iter<'a, T> {}
826 #[stable(feature = "rust1", since = "1.0.0")]
827 unsafe impl<'a, T: Sync> Send for Iter<'a, T> {}
829 impl<'a, T> Iter<'a, T> {
830 /// View the underlying data as a subslice of the original data.
832 /// This has the same lifetime as the original slice, and so the
833 /// iterator can continue to be used while this exists.
834 #[stable(feature = "iter_to_slice", since = "1.4.0")]
835 pub fn as_slice(&self) -> &'a [T] {
836 make_slice!(self.ptr, self.end)
839 // Helper function for Iter::nth
840 fn iter_nth(&mut self, n: usize) -> Option<&'a T> {
841 match self.as_slice().get(n) {
842 Some(elem_ref) => unsafe {
843 self.ptr = slice_offset!(self.ptr, (n as isize).wrapping_add(1));
854 iterator!{struct Iter -> *const T, &'a T}
856 #[stable(feature = "rust1", since = "1.0.0")]
857 impl<'a, T> ExactSizeIterator for Iter<'a, T> {}
859 #[stable(feature = "rust1", since = "1.0.0")]
860 impl<'a, T> Clone for Iter<'a, T> {
861 fn clone(&self) -> Iter<'a, T> { Iter { ptr: self.ptr, end: self.end, _marker: self._marker } }
864 /// Mutable slice iterator.
865 #[stable(feature = "rust1", since = "1.0.0")]
866 pub struct IterMut<'a, T: 'a> {
869 _marker: marker::PhantomData<&'a mut T>,
872 #[stable(feature = "rust1", since = "1.0.0")]
873 unsafe impl<'a, T: Sync> Sync for IterMut<'a, T> {}
874 #[stable(feature = "rust1", since = "1.0.0")]
875 unsafe impl<'a, T: Send> Send for IterMut<'a, T> {}
877 impl<'a, T> IterMut<'a, T> {
878 /// View the underlying data as a subslice of the original data.
880 /// To avoid creating `&mut` references that alias, this is forced
881 /// to consume the iterator. Consider using the `Slice` and
882 /// `SliceMut` implementations for obtaining slices with more
883 /// restricted lifetimes that do not consume the iterator.
884 #[stable(feature = "iter_to_slice", since = "1.4.0")]
885 pub fn into_slice(self) -> &'a mut [T] {
886 make_mut_slice!(self.ptr, self.end)
889 // Helper function for IterMut::nth
890 fn iter_nth(&mut self, n: usize) -> Option<&'a mut T> {
891 match make_mut_slice!(self.ptr, self.end).get_mut(n) {
892 Some(elem_ref) => unsafe {
893 self.ptr = slice_offset!(self.ptr, (n as isize).wrapping_add(1));
904 iterator!{struct IterMut -> *mut T, &'a mut T}
906 #[stable(feature = "rust1", since = "1.0.0")]
907 impl<'a, T> ExactSizeIterator for IterMut<'a, T> {}
909 /// An internal abstraction over the splitting iterators, so that
910 /// splitn, splitn_mut etc can be implemented once.
911 trait SplitIter: DoubleEndedIterator {
912 /// Mark the underlying iterator as complete, extracting the remaining
913 /// portion of the slice.
914 fn finish(&mut self) -> Option<Self::Item>;
917 /// An iterator over subslices separated by elements that match a predicate
919 #[stable(feature = "rust1", since = "1.0.0")]
920 pub struct Split<'a, T:'a, P> where P: FnMut(&T) -> bool {
926 // FIXME(#19839) Remove in favor of `#[derive(Clone)]`
927 #[stable(feature = "rust1", since = "1.0.0")]
928 impl<'a, T, P> Clone for Split<'a, T, P> where P: Clone + FnMut(&T) -> bool {
929 fn clone(&self) -> Split<'a, T, P> {
932 pred: self.pred.clone(),
933 finished: self.finished,
938 #[stable(feature = "rust1", since = "1.0.0")]
939 impl<'a, T, P> Iterator for Split<'a, T, P> where P: FnMut(&T) -> bool {
943 fn next(&mut self) -> Option<&'a [T]> {
944 if self.finished { return None; }
946 match self.v.iter().position(|x| (self.pred)(x)) {
947 None => self.finish(),
949 let ret = Some(&self.v[..idx]);
950 self.v = &self.v[idx + 1..];
957 fn size_hint(&self) -> (usize, Option<usize>) {
961 (1, Some(self.v.len() + 1))
966 #[stable(feature = "rust1", since = "1.0.0")]
967 impl<'a, T, P> DoubleEndedIterator for Split<'a, T, P> where P: FnMut(&T) -> bool {
969 fn next_back(&mut self) -> Option<&'a [T]> {
970 if self.finished { return None; }
972 match self.v.iter().rposition(|x| (self.pred)(x)) {
973 None => self.finish(),
975 let ret = Some(&self.v[idx + 1..]);
976 self.v = &self.v[..idx];
983 impl<'a, T, P> SplitIter for Split<'a, T, P> where P: FnMut(&T) -> bool {
985 fn finish(&mut self) -> Option<&'a [T]> {
986 if self.finished { None } else { self.finished = true; Some(self.v) }
990 /// An iterator over the subslices of the vector which are separated
991 /// by elements that match `pred`.
992 #[stable(feature = "rust1", since = "1.0.0")]
993 pub struct SplitMut<'a, T:'a, P> where P: FnMut(&T) -> bool {
999 impl<'a, T, P> SplitIter for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {
1001 fn finish(&mut self) -> Option<&'a mut [T]> {
1005 self.finished = true;
1006 Some(mem::replace(&mut self.v, &mut []))
1011 #[stable(feature = "rust1", since = "1.0.0")]
1012 impl<'a, T, P> Iterator for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {
1013 type Item = &'a mut [T];
1016 fn next(&mut self) -> Option<&'a mut [T]> {
1017 if self.finished { return None; }
1019 let idx_opt = { // work around borrowck limitations
1020 let pred = &mut self.pred;
1021 self.v.iter().position(|x| (*pred)(x))
1024 None => self.finish(),
1026 let tmp = mem::replace(&mut self.v, &mut []);
1027 let (head, tail) = tmp.split_at_mut(idx);
1028 self.v = &mut tail[1..];
1035 fn size_hint(&self) -> (usize, Option<usize>) {
1039 // if the predicate doesn't match anything, we yield one slice
1040 // if it matches every element, we yield len+1 empty slices.
1041 (1, Some(self.v.len() + 1))
1046 #[stable(feature = "rust1", since = "1.0.0")]
1047 impl<'a, T, P> DoubleEndedIterator for SplitMut<'a, T, P> where
1048 P: FnMut(&T) -> bool,
1051 fn next_back(&mut self) -> Option<&'a mut [T]> {
1052 if self.finished { return None; }
1054 let idx_opt = { // work around borrowck limitations
1055 let pred = &mut self.pred;
1056 self.v.iter().rposition(|x| (*pred)(x))
1059 None => self.finish(),
1061 let tmp = mem::replace(&mut self.v, &mut []);
1062 let (head, tail) = tmp.split_at_mut(idx);
1064 Some(&mut tail[1..])
1070 /// An private iterator over subslices separated by elements that
1071 /// match a predicate function, splitting at most a fixed number of
1073 struct GenericSplitN<I> {
1079 impl<T, I: SplitIter<Item=T>> Iterator for GenericSplitN<I> {
1083 fn next(&mut self) -> Option<T> {
1086 1 => { self.count -= 1; self.iter.finish() }
1089 if self.invert {self.iter.next_back()} else {self.iter.next()}
1095 fn size_hint(&self) -> (usize, Option<usize>) {
1096 let (lower, upper_opt) = self.iter.size_hint();
1097 (lower, upper_opt.map(|upper| cmp::min(self.count, upper)))
1101 /// An iterator over subslices separated by elements that match a predicate
1102 /// function, limited to a given number of splits.
1103 #[stable(feature = "rust1", since = "1.0.0")]
1104 pub struct SplitN<'a, T: 'a, P> where P: FnMut(&T) -> bool {
1105 inner: GenericSplitN<Split<'a, T, P>>
1108 /// An iterator over subslices separated by elements that match a
1109 /// predicate function, limited to a given number of splits, starting
1110 /// from the end of the slice.
1111 #[stable(feature = "rust1", since = "1.0.0")]
1112 pub struct RSplitN<'a, T: 'a, P> where P: FnMut(&T) -> bool {
1113 inner: GenericSplitN<Split<'a, T, P>>
1116 /// An iterator over subslices separated by elements that match a predicate
1117 /// function, limited to a given number of splits.
1118 #[stable(feature = "rust1", since = "1.0.0")]
1119 pub struct SplitNMut<'a, T: 'a, P> where P: FnMut(&T) -> bool {
1120 inner: GenericSplitN<SplitMut<'a, T, P>>
1123 /// An iterator over subslices separated by elements that match a
1124 /// predicate function, limited to a given number of splits, starting
1125 /// from the end of the slice.
1126 #[stable(feature = "rust1", since = "1.0.0")]
1127 pub struct RSplitNMut<'a, T: 'a, P> where P: FnMut(&T) -> bool {
1128 inner: GenericSplitN<SplitMut<'a, T, P>>
1131 macro_rules! forward_iterator {
1132 ($name:ident: $elem:ident, $iter_of:ty) => {
1133 #[stable(feature = "rust1", since = "1.0.0")]
1134 impl<'a, $elem, P> Iterator for $name<'a, $elem, P> where
1135 P: FnMut(&T) -> bool
1137 type Item = $iter_of;
1140 fn next(&mut self) -> Option<$iter_of> {
1145 fn size_hint(&self) -> (usize, Option<usize>) {
1146 self.inner.size_hint()
1152 forward_iterator! { SplitN: T, &'a [T] }
1153 forward_iterator! { RSplitN: T, &'a [T] }
1154 forward_iterator! { SplitNMut: T, &'a mut [T] }
1155 forward_iterator! { RSplitNMut: T, &'a mut [T] }
1157 /// An iterator over overlapping subslices of length `size`.
1158 #[stable(feature = "rust1", since = "1.0.0")]
1159 pub struct Windows<'a, T:'a> {
1164 // FIXME(#19839) Remove in favor of `#[derive(Clone)]`
1165 #[stable(feature = "rust1", since = "1.0.0")]
1166 impl<'a, T> Clone for Windows<'a, T> {
1167 fn clone(&self) -> Windows<'a, T> {
1175 #[stable(feature = "rust1", since = "1.0.0")]
1176 impl<'a, T> Iterator for Windows<'a, T> {
1177 type Item = &'a [T];
1180 fn next(&mut self) -> Option<&'a [T]> {
1181 if self.size > self.v.len() {
1184 let ret = Some(&self.v[..self.size]);
1185 self.v = &self.v[1..];
1191 fn size_hint(&self) -> (usize, Option<usize>) {
1192 if self.size > self.v.len() {
1195 let size = self.v.len() - self.size + 1;
1201 fn count(self) -> usize {
1206 fn nth(&mut self, n: usize) -> Option<Self::Item> {
1207 let (end, overflow) = self.size.overflowing_add(n);
1208 if end > self.v.len() || overflow {
1212 let nth = &self.v[n..end];
1213 self.v = &self.v[n+1..];
1219 fn last(self) -> Option<Self::Item> {
1220 if self.size > self.v.len() {
1223 let start = self.v.len() - self.size;
1224 Some(&self.v[start..])
1229 #[stable(feature = "rust1", since = "1.0.0")]
1230 impl<'a, T> DoubleEndedIterator for Windows<'a, T> {
1232 fn next_back(&mut self) -> Option<&'a [T]> {
1233 if self.size > self.v.len() {
1236 let ret = Some(&self.v[self.v.len()-self.size..]);
1237 self.v = &self.v[..self.v.len()-1];
1243 #[stable(feature = "rust1", since = "1.0.0")]
1244 impl<'a, T> ExactSizeIterator for Windows<'a, T> {}
1246 /// An iterator over a slice in (non-overlapping) chunks (`size` elements at a
1249 /// When the slice len is not evenly divided by the chunk size, the last slice
1250 /// of the iteration will be the remainder.
1251 #[stable(feature = "rust1", since = "1.0.0")]
1252 pub struct Chunks<'a, T:'a> {
1257 // FIXME(#19839) Remove in favor of `#[derive(Clone)]`
1258 #[stable(feature = "rust1", since = "1.0.0")]
1259 impl<'a, T> Clone for Chunks<'a, T> {
1260 fn clone(&self) -> Chunks<'a, T> {
1268 #[stable(feature = "rust1", since = "1.0.0")]
1269 impl<'a, T> Iterator for Chunks<'a, T> {
1270 type Item = &'a [T];
1273 fn next(&mut self) -> Option<&'a [T]> {
1274 if self.v.is_empty() {
1277 let chunksz = cmp::min(self.v.len(), self.size);
1278 let (fst, snd) = self.v.split_at(chunksz);
1285 fn size_hint(&self) -> (usize, Option<usize>) {
1286 if self.v.is_empty() {
1289 let n = self.v.len() / self.size;
1290 let rem = self.v.len() % self.size;
1291 let n = if rem > 0 { n+1 } else { n };
1297 fn count(self) -> usize {
1302 fn nth(&mut self, n: usize) -> Option<Self::Item> {
1303 let (start, overflow) = n.overflowing_mul(self.size);
1304 if start >= self.v.len() || overflow {
1308 let end = match start.checked_add(self.size) {
1309 Some(sum) => cmp::min(self.v.len(), sum),
1310 None => self.v.len(),
1312 let nth = &self.v[start..end];
1313 self.v = &self.v[end..];
1319 fn last(self) -> Option<Self::Item> {
1320 if self.v.is_empty() {
1323 let start = (self.v.len() - 1) / self.size * self.size;
1324 Some(&self.v[start..])
1329 #[stable(feature = "rust1", since = "1.0.0")]
1330 impl<'a, T> DoubleEndedIterator for Chunks<'a, T> {
1332 fn next_back(&mut self) -> Option<&'a [T]> {
1333 if self.v.is_empty() {
1336 let remainder = self.v.len() % self.size;
1337 let chunksz = if remainder != 0 { remainder } else { self.size };
1338 let (fst, snd) = self.v.split_at(self.v.len() - chunksz);
1345 #[stable(feature = "rust1", since = "1.0.0")]
1346 impl<'a, T> ExactSizeIterator for Chunks<'a, T> {}
1348 /// An iterator over a slice in (non-overlapping) mutable chunks (`size`
1349 /// elements at a time). When the slice len is not evenly divided by the chunk
1350 /// size, the last slice of the iteration will be the remainder.
1351 #[stable(feature = "rust1", since = "1.0.0")]
1352 pub struct ChunksMut<'a, T:'a> {
1357 #[stable(feature = "rust1", since = "1.0.0")]
1358 impl<'a, T> Iterator for ChunksMut<'a, T> {
1359 type Item = &'a mut [T];
1362 fn next(&mut self) -> Option<&'a mut [T]> {
1363 if self.v.is_empty() {
1366 let sz = cmp::min(self.v.len(), self.chunk_size);
1367 let tmp = mem::replace(&mut self.v, &mut []);
1368 let (head, tail) = tmp.split_at_mut(sz);
1375 fn size_hint(&self) -> (usize, Option<usize>) {
1376 if self.v.is_empty() {
1379 let n = self.v.len() / self.chunk_size;
1380 let rem = self.v.len() % self.chunk_size;
1381 let n = if rem > 0 { n + 1 } else { n };
1387 fn count(self) -> usize {
1392 fn nth(&mut self, n: usize) -> Option<&'a mut [T]> {
1393 let (start, overflow) = n.overflowing_mul(self.chunk_size);
1394 if start >= self.v.len() || overflow {
1398 let end = match start.checked_add(self.chunk_size) {
1399 Some(sum) => cmp::min(self.v.len(), sum),
1400 None => self.v.len(),
1402 let tmp = mem::replace(&mut self.v, &mut []);
1403 let (head, tail) = tmp.split_at_mut(end);
1404 let (_, nth) = head.split_at_mut(start);
1411 fn last(self) -> Option<Self::Item> {
1412 if self.v.is_empty() {
1415 let start = (self.v.len() - 1) / self.chunk_size * self.chunk_size;
1416 Some(&mut self.v[start..])
1421 #[stable(feature = "rust1", since = "1.0.0")]
1422 impl<'a, T> DoubleEndedIterator for ChunksMut<'a, T> {
1424 fn next_back(&mut self) -> Option<&'a mut [T]> {
1425 if self.v.is_empty() {
1428 let remainder = self.v.len() % self.chunk_size;
1429 let sz = if remainder != 0 { remainder } else { self.chunk_size };
1430 let tmp = mem::replace(&mut self.v, &mut []);
1431 let tmp_len = tmp.len();
1432 let (head, tail) = tmp.split_at_mut(tmp_len - sz);
1439 #[stable(feature = "rust1", since = "1.0.0")]
1440 impl<'a, T> ExactSizeIterator for ChunksMut<'a, T> {}
1446 /// Forms a slice from a pointer and a length.
1448 /// The `len` argument is the number of **elements**, not the number of bytes.
1452 /// This function is unsafe as there is no guarantee that the given pointer is
1453 /// valid for `len` elements, nor whether the lifetime inferred is a suitable
1454 /// lifetime for the returned slice.
1456 /// `p` must be non-null, even for zero-length slices.
1460 /// The lifetime for the returned slice is inferred from its usage. To
1461 /// prevent accidental misuse, it's suggested to tie the lifetime to whichever
1462 /// source lifetime is safe in the context, such as by providing a helper
1463 /// function taking the lifetime of a host value for the slice, or by explicit
1471 /// // manifest a slice out of thin air!
1472 /// let ptr = 0x1234 as *const usize;
1475 /// let slice = slice::from_raw_parts(ptr, amt);
1479 #[stable(feature = "rust1", since = "1.0.0")]
1480 pub unsafe fn from_raw_parts<'a, T>(p: *const T, len: usize) -> &'a [T] {
1481 mem::transmute(RawSlice { data: p, len: len })
1484 /// Performs the same functionality as `from_raw_parts`, except that a mutable
1485 /// slice is returned.
1487 /// This function is unsafe for the same reasons as `from_raw_parts`, as well
1488 /// as not being able to provide a non-aliasing guarantee of the returned
1491 #[stable(feature = "rust1", since = "1.0.0")]
1492 pub unsafe fn from_raw_parts_mut<'a, T>(p: *mut T, len: usize) -> &'a mut [T] {
1493 mem::transmute(RawSlice { data: p, len: len })
1500 /// Operations on `[u8]`.
1501 #[unstable(feature = "slice_bytes", reason = "needs review",
1503 #[rustc_deprecated(reason = "unidiomatic functions not pulling their weight",
1505 #[allow(deprecated)]
1508 use slice::SliceExt;
1510 /// A trait for operations on mutable `[u8]`s.
1511 pub trait MutableByteVector {
1512 /// Sets all bytes of the receiver to the given value.
1513 fn set_memory(&mut self, value: u8);
1516 impl MutableByteVector for [u8] {
1518 fn set_memory(&mut self, value: u8) {
1519 unsafe { ptr::write_bytes(self.as_mut_ptr(), value, self.len()) };
1523 /// Copies data from `src` to `dst`
1525 /// Panics if the length of `dst` is less than the length of `src`.
1527 pub fn copy_memory(src: &[u8], dst: &mut [u8]) {
1528 let len_src = src.len();
1529 assert!(dst.len() >= len_src);
1530 // `dst` is unaliasable, so we know statically it doesn't overlap
1533 ptr::copy_nonoverlapping(src.as_ptr(),
1543 // Boilerplate traits
1546 #[stable(feature = "rust1", since = "1.0.0")]
1547 impl<A, B> PartialEq<[B]> for [A] where A: PartialEq<B> {
1548 fn eq(&self, other: &[B]) -> bool {
1549 if self.len() != other.len() {
1553 for i in 0..self.len() {
1554 if !self[i].eq(&other[i]) {
1561 fn ne(&self, other: &[B]) -> bool {
1562 if self.len() != other.len() {
1566 for i in 0..self.len() {
1567 if self[i].ne(&other[i]) {
1576 #[stable(feature = "rust1", since = "1.0.0")]
1577 impl<T: Eq> Eq for [T] {}
1579 #[stable(feature = "rust1", since = "1.0.0")]
1580 impl<T: Ord> Ord for [T] {
1581 fn cmp(&self, other: &[T]) -> Ordering {
1582 let l = cmp::min(self.len(), other.len());
1584 // Slice to the loop iteration range to enable bound check
1585 // elimination in the compiler
1586 let lhs = &self[..l];
1587 let rhs = &other[..l];
1590 match lhs[i].cmp(&rhs[i]) {
1591 Ordering::Equal => (),
1592 non_eq => return non_eq,
1596 self.len().cmp(&other.len())
1600 #[stable(feature = "rust1", since = "1.0.0")]
1601 impl<T: PartialOrd> PartialOrd for [T] {
1602 fn partial_cmp(&self, other: &[T]) -> Option<Ordering> {
1603 let l = cmp::min(self.len(), other.len());
1605 // Slice to the loop iteration range to enable bound check
1606 // elimination in the compiler
1607 let lhs = &self[..l];
1608 let rhs = &other[..l];
1611 match lhs[i].partial_cmp(&rhs[i]) {
1612 Some(Ordering::Equal) => (),
1613 non_eq => return non_eq,
1617 self.len().partial_cmp(&other.len())