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::{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;
157 // Use macros to be generic over const/mut
158 macro_rules! slice_offset {
159 ($ptr:expr, $by:expr) => {{
161 if size_from_ptr(ptr) == 0 {
162 ::intrinsics::arith_offset(ptr as *mut i8, $by) as *mut _
169 macro_rules! slice_ref {
172 if size_from_ptr(ptr) == 0 {
173 // Use a non-null pointer value
181 #[unstable(feature = "core_slice_ext",
182 reason = "stable interface provided by `impl [T]` in later crates",
184 impl<T> SliceExt for [T] {
188 fn split_at(&self, mid: usize) -> (&[T], &[T]) {
189 (&self[..mid], &self[mid..])
193 fn iter(&self) -> Iter<T> {
195 let p = if mem::size_of::<T>() == 0 {
198 let p = self.as_ptr();
199 assume(!p.is_null());
205 end: slice_offset!(p, self.len() as isize),
206 _marker: marker::PhantomData
212 fn split<P>(&self, pred: P) -> Split<T, P> where P: FnMut(&T) -> bool {
221 fn splitn<P>(&self, n: usize, pred: P) -> SplitN<T, P> where
222 P: FnMut(&T) -> bool,
225 inner: GenericSplitN {
226 iter: self.split(pred),
234 fn rsplitn<P>(&self, n: usize, pred: P) -> RSplitN<T, P> where
235 P: FnMut(&T) -> bool,
238 inner: GenericSplitN {
239 iter: self.split(pred),
247 fn windows(&self, size: usize) -> Windows<T> {
249 Windows { v: self, size: size }
253 fn chunks(&self, size: usize) -> Chunks<T> {
255 Chunks { v: self, size: size }
259 fn get(&self, index: usize) -> Option<&T> {
260 if index < self.len() { Some(&self[index]) } else { None }
264 fn first(&self) -> Option<&T> {
265 if self.is_empty() { None } else { Some(&self[0]) }
269 fn split_first(&self) -> Option<(&T, &[T])> {
270 if self.is_empty() { None } else { Some((&self[0], &self[1..])) }
274 fn split_last(&self) -> Option<(&T, &[T])> {
275 let len = self.len();
276 if len == 0 { None } else { Some((&self[len - 1], &self[..(len - 1)])) }
280 fn last(&self) -> Option<&T> {
281 if self.is_empty() { None } else { Some(&self[self.len() - 1]) }
285 unsafe fn get_unchecked(&self, index: usize) -> &T {
286 &*(self.repr().data.offset(index as isize))
290 fn as_ptr(&self) -> *const T {
294 fn binary_search_by<F>(&self, mut f: F) -> Result<usize, usize> where
295 F: FnMut(&T) -> Ordering
297 let mut base = 0usize;
301 let (head, tail) = s.split_at(s.len() >> 1);
307 base += head.len() + 1;
311 Equal => return Ok(base + head.len()),
317 fn len(&self) -> usize { self.repr().len }
320 fn get_mut(&mut self, index: usize) -> Option<&mut T> {
321 if index < self.len() { Some(&mut self[index]) } else { None }
325 fn split_at_mut(&mut self, mid: usize) -> (&mut [T], &mut [T]) {
326 let len = self.len();
327 let ptr = self.as_mut_ptr();
332 (from_raw_parts_mut(ptr, mid),
333 from_raw_parts_mut(ptr.offset(mid as isize), len - mid))
338 fn iter_mut(&mut self) -> IterMut<T> {
340 let p = if mem::size_of::<T>() == 0 {
343 let p = self.as_mut_ptr();
344 assume(!p.is_null());
350 end: slice_offset!(p, self.len() as isize),
351 _marker: marker::PhantomData
357 fn last_mut(&mut self) -> Option<&mut T> {
358 let len = self.len();
359 if len == 0 { return None; }
360 Some(&mut self[len - 1])
364 fn first_mut(&mut self) -> Option<&mut T> {
365 if self.is_empty() { None } else { Some(&mut self[0]) }
369 fn split_first_mut(&mut self) -> Option<(&mut T, &mut [T])> {
370 if self.is_empty() { None } else {
371 let split = self.split_at_mut(1);
372 Some((&mut split.0[0], split.1))
377 fn split_last_mut(&mut self) -> Option<(&mut T, &mut [T])> {
378 let len = self.len();
379 if len == 0 { None } else {
380 let split = self.split_at_mut(len - 1);
381 Some((&mut split.1[0], split.0))
386 fn split_mut<P>(&mut self, pred: P) -> SplitMut<T, P> where P: FnMut(&T) -> bool {
387 SplitMut { v: self, pred: pred, finished: false }
391 fn splitn_mut<P>(&mut self, n: usize, pred: P) -> SplitNMut<T, P> where
395 inner: GenericSplitN {
396 iter: self.split_mut(pred),
404 fn rsplitn_mut<P>(&mut self, n: usize, pred: P) -> RSplitNMut<T, P> where
405 P: FnMut(&T) -> bool,
408 inner: GenericSplitN {
409 iter: self.split_mut(pred),
417 fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<T> {
418 assert!(chunk_size > 0);
419 ChunksMut { v: self, chunk_size: chunk_size }
423 fn swap(&mut self, a: usize, b: usize) {
425 // Can't take two mutable loans from one vector, so instead just cast
426 // them to their raw pointers to do the swap
427 let pa: *mut T = &mut self[a];
428 let pb: *mut T = &mut self[b];
433 fn reverse(&mut self) {
434 let mut i: usize = 0;
437 // Unsafe swap to avoid the bounds check in safe swap.
439 let pa: *mut T = self.get_unchecked_mut(i);
440 let pb: *mut T = self.get_unchecked_mut(ln - i - 1);
448 unsafe fn get_unchecked_mut(&mut self, index: usize) -> &mut T {
449 &mut *(self.repr().data as *mut T).offset(index as isize)
453 fn as_mut_ptr(&mut self) -> *mut T {
454 self.repr().data as *mut T
458 fn contains(&self, x: &T) -> bool where T: PartialEq {
459 self.iter().any(|elt| *x == *elt)
463 fn starts_with(&self, needle: &[T]) -> bool where T: PartialEq {
464 let n = needle.len();
465 self.len() >= n && needle == &self[..n]
469 fn ends_with(&self, needle: &[T]) -> bool where T: PartialEq {
470 let (m, n) = (self.len(), needle.len());
471 m >= n && needle == &self[m-n..]
474 fn binary_search(&self, x: &T) -> Result<usize, usize> where T: Ord {
475 self.binary_search_by(|p| p.cmp(x))
479 fn clone_from_slice(&mut self, src: &[T]) where T: Clone {
480 assert!(self.len() == src.len(),
481 "destination and source slices have different lengths");
482 // NOTE: We need to explicitly slice them to the same length
483 // for bounds checking to be elided, and the optimizer will
484 // generate memcpy for simple cases (for example T = u8).
485 let len = self.len();
486 let src = &src[..len];
488 self[i].clone_from(&src[i]);
493 #[stable(feature = "rust1", since = "1.0.0")]
494 impl<T> ops::Index<usize> for [T] {
497 fn index(&self, index: usize) -> &T {
498 assert!(index < self.len());
499 unsafe { self.get_unchecked(index) }
503 #[stable(feature = "rust1", since = "1.0.0")]
504 impl<T> ops::IndexMut<usize> for [T] {
506 fn index_mut(&mut self, index: usize) -> &mut T {
507 assert!(index < self.len());
508 unsafe { self.get_unchecked_mut(index) }
514 fn slice_index_len_fail(index: usize, len: usize) -> ! {
515 panic!("index {} out of range for slice of length {}", index, len);
520 fn slice_index_order_fail(index: usize, end: usize) -> ! {
521 panic!("slice index starts at {} but ends at {}", index, end);
524 #[stable(feature = "rust1", since = "1.0.0")]
525 impl<T> ops::Index<ops::Range<usize>> for [T] {
529 fn index(&self, index: ops::Range<usize>) -> &[T] {
530 if index.start > index.end {
531 slice_index_order_fail(index.start, index.end);
532 } else if index.end > self.len() {
533 slice_index_len_fail(index.end, self.len());
537 self.as_ptr().offset(index.start as isize),
538 index.end - index.start
543 #[stable(feature = "rust1", since = "1.0.0")]
544 impl<T> ops::Index<ops::RangeTo<usize>> for [T] {
548 fn index(&self, index: ops::RangeTo<usize>) -> &[T] {
549 self.index(ops::Range{ start: 0, end: index.end })
552 #[stable(feature = "rust1", since = "1.0.0")]
553 impl<T> ops::Index<ops::RangeFrom<usize>> for [T] {
557 fn index(&self, index: ops::RangeFrom<usize>) -> &[T] {
558 self.index(ops::Range{ start: index.start, end: self.len() })
561 #[stable(feature = "rust1", since = "1.0.0")]
562 impl<T> ops::Index<RangeFull> for [T] {
566 fn index(&self, _index: RangeFull) -> &[T] {
571 #[stable(feature = "rust1", since = "1.0.0")]
572 impl<T> ops::IndexMut<ops::Range<usize>> for [T] {
574 fn index_mut(&mut self, index: ops::Range<usize>) -> &mut [T] {
575 if index.start > index.end {
576 slice_index_order_fail(index.start, index.end);
577 } else if index.end > self.len() {
578 slice_index_len_fail(index.end, self.len());
582 self.as_mut_ptr().offset(index.start as isize),
583 index.end - index.start
588 #[stable(feature = "rust1", since = "1.0.0")]
589 impl<T> ops::IndexMut<ops::RangeTo<usize>> for [T] {
591 fn index_mut(&mut self, index: ops::RangeTo<usize>) -> &mut [T] {
592 self.index_mut(ops::Range{ start: 0, end: index.end })
595 #[stable(feature = "rust1", since = "1.0.0")]
596 impl<T> ops::IndexMut<ops::RangeFrom<usize>> for [T] {
598 fn index_mut(&mut self, index: ops::RangeFrom<usize>) -> &mut [T] {
599 let len = self.len();
600 self.index_mut(ops::Range{ start: index.start, end: len })
603 #[stable(feature = "rust1", since = "1.0.0")]
604 impl<T> ops::IndexMut<RangeFull> for [T] {
606 fn index_mut(&mut self, _index: RangeFull) -> &mut [T] {
612 ////////////////////////////////////////////////////////////////////////////////
614 ////////////////////////////////////////////////////////////////////////////////
616 #[stable(feature = "rust1", since = "1.0.0")]
617 impl<'a, T> Default for &'a [T] {
618 fn default() -> &'a [T] { &[] }
621 #[stable(feature = "mut_slice_default", since = "1.5.0")]
622 impl<'a, T> Default for &'a mut [T] {
623 fn default() -> &'a mut [T] { &mut [] }
630 #[stable(feature = "rust1", since = "1.0.0")]
631 impl<'a, T> IntoIterator for &'a [T] {
633 type IntoIter = Iter<'a, T>;
635 fn into_iter(self) -> Iter<'a, T> {
640 #[stable(feature = "rust1", since = "1.0.0")]
641 impl<'a, T> IntoIterator for &'a mut [T] {
642 type Item = &'a mut T;
643 type IntoIter = IterMut<'a, T>;
645 fn into_iter(self) -> IterMut<'a, T> {
651 fn size_from_ptr<T>(_: *const T) -> usize {
655 // The shared definition of the `Iter` and `IterMut` iterators
656 macro_rules! iterator {
657 (struct $name:ident -> $ptr:ty, $elem:ty) => {
658 #[stable(feature = "rust1", since = "1.0.0")]
659 impl<'a, T> Iterator for $name<'a, T> {
663 fn next(&mut self) -> Option<$elem> {
664 // could be implemented with slices, but this avoids bounds checks
666 if mem::size_of::<T>() != 0 {
667 assume(!self.ptr.is_null());
668 assume(!self.end.is_null());
670 if self.ptr == self.end {
674 self.ptr = slice_offset!(self.ptr, 1);
675 Some(slice_ref!(old))
681 fn size_hint(&self) -> (usize, Option<usize>) {
682 let diff = (self.end as usize).wrapping_sub(self.ptr as usize);
683 let size = mem::size_of::<T>();
684 let exact = diff / (if size == 0 {1} else {size});
689 fn count(self) -> usize {
694 fn nth(&mut self, n: usize) -> Option<$elem> {
695 // Call helper method. Can't put the definition here because mut versus const.
700 fn last(mut self) -> Option<$elem> {
705 #[stable(feature = "rust1", since = "1.0.0")]
706 impl<'a, T> DoubleEndedIterator for $name<'a, T> {
708 fn next_back(&mut self) -> Option<$elem> {
709 // could be implemented with slices, but this avoids bounds checks
711 if mem::size_of::<T>() != 0 {
712 assume(!self.ptr.is_null());
713 assume(!self.end.is_null());
715 if self.end == self.ptr {
718 self.end = slice_offset!(self.end, -1);
719 Some(slice_ref!(self.end))
727 macro_rules! make_slice {
728 ($start: expr, $end: expr) => {{
730 let diff = ($end as usize).wrapping_sub(start as usize);
731 if size_from_ptr(start) == 0 {
732 // use a non-null pointer value
733 unsafe { from_raw_parts(1 as *const _, diff) }
735 let len = diff / size_from_ptr(start);
736 unsafe { from_raw_parts(start, len) }
741 macro_rules! make_mut_slice {
742 ($start: expr, $end: expr) => {{
744 let diff = ($end as usize).wrapping_sub(start as usize);
745 if size_from_ptr(start) == 0 {
746 // use a non-null pointer value
747 unsafe { from_raw_parts_mut(1 as *mut _, diff) }
749 let len = diff / size_from_ptr(start);
750 unsafe { from_raw_parts_mut(start, len) }
755 /// Immutable slice iterator
756 #[stable(feature = "rust1", since = "1.0.0")]
757 pub struct Iter<'a, T: 'a> {
760 _marker: marker::PhantomData<&'a T>,
763 #[stable(feature = "rust1", since = "1.0.0")]
764 unsafe impl<'a, T: Sync> Sync for Iter<'a, T> {}
765 #[stable(feature = "rust1", since = "1.0.0")]
766 unsafe impl<'a, T: Sync> Send for Iter<'a, T> {}
768 impl<'a, T> Iter<'a, T> {
769 /// View the underlying data as a subslice of the original data.
771 /// This has the same lifetime as the original slice, and so the
772 /// iterator can continue to be used while this exists.
773 #[stable(feature = "iter_to_slice", since = "1.4.0")]
774 pub fn as_slice(&self) -> &'a [T] {
775 make_slice!(self.ptr, self.end)
778 // Helper function for Iter::nth
779 fn iter_nth(&mut self, n: usize) -> Option<&'a T> {
780 match self.as_slice().get(n) {
781 Some(elem_ref) => unsafe {
782 self.ptr = slice_offset!(self.ptr, (n as isize).wrapping_add(1));
793 iterator!{struct Iter -> *const T, &'a T}
795 #[stable(feature = "rust1", since = "1.0.0")]
796 impl<'a, T> ExactSizeIterator for Iter<'a, T> {}
798 #[stable(feature = "rust1", since = "1.0.0")]
799 impl<'a, T> Clone for Iter<'a, T> {
800 fn clone(&self) -> Iter<'a, T> { Iter { ptr: self.ptr, end: self.end, _marker: self._marker } }
803 /// Mutable slice iterator.
804 #[stable(feature = "rust1", since = "1.0.0")]
805 pub struct IterMut<'a, T: 'a> {
808 _marker: marker::PhantomData<&'a mut T>,
811 #[stable(feature = "rust1", since = "1.0.0")]
812 unsafe impl<'a, T: Sync> Sync for IterMut<'a, T> {}
813 #[stable(feature = "rust1", since = "1.0.0")]
814 unsafe impl<'a, T: Send> Send for IterMut<'a, T> {}
816 impl<'a, T> IterMut<'a, T> {
817 /// View the underlying data as a subslice of the original data.
819 /// To avoid creating `&mut` references that alias, this is forced
820 /// to consume the iterator. Consider using the `Slice` and
821 /// `SliceMut` implementations for obtaining slices with more
822 /// restricted lifetimes that do not consume the iterator.
823 #[stable(feature = "iter_to_slice", since = "1.4.0")]
824 pub fn into_slice(self) -> &'a mut [T] {
825 make_mut_slice!(self.ptr, self.end)
828 // Helper function for IterMut::nth
829 fn iter_nth(&mut self, n: usize) -> Option<&'a mut T> {
830 match make_mut_slice!(self.ptr, self.end).get_mut(n) {
831 Some(elem_ref) => unsafe {
832 self.ptr = slice_offset!(self.ptr, (n as isize).wrapping_add(1));
843 iterator!{struct IterMut -> *mut T, &'a mut T}
845 #[stable(feature = "rust1", since = "1.0.0")]
846 impl<'a, T> ExactSizeIterator for IterMut<'a, T> {}
848 /// An internal abstraction over the splitting iterators, so that
849 /// splitn, splitn_mut etc can be implemented once.
850 trait SplitIter: DoubleEndedIterator {
851 /// Mark the underlying iterator as complete, extracting the remaining
852 /// portion of the slice.
853 fn finish(&mut self) -> Option<Self::Item>;
856 /// An iterator over subslices separated by elements that match a predicate
858 #[stable(feature = "rust1", since = "1.0.0")]
859 pub struct Split<'a, T:'a, P> where P: FnMut(&T) -> bool {
865 // FIXME(#19839) Remove in favor of `#[derive(Clone)]`
866 #[stable(feature = "rust1", since = "1.0.0")]
867 impl<'a, T, P> Clone for Split<'a, T, P> where P: Clone + FnMut(&T) -> bool {
868 fn clone(&self) -> Split<'a, T, P> {
871 pred: self.pred.clone(),
872 finished: self.finished,
877 #[stable(feature = "rust1", since = "1.0.0")]
878 impl<'a, T, P> Iterator for Split<'a, T, P> where P: FnMut(&T) -> bool {
882 fn next(&mut self) -> Option<&'a [T]> {
883 if self.finished { return None; }
885 match self.v.iter().position(|x| (self.pred)(x)) {
886 None => self.finish(),
888 let ret = Some(&self.v[..idx]);
889 self.v = &self.v[idx + 1..];
896 fn size_hint(&self) -> (usize, Option<usize>) {
900 (1, Some(self.v.len() + 1))
905 #[stable(feature = "rust1", since = "1.0.0")]
906 impl<'a, T, P> DoubleEndedIterator for Split<'a, T, P> where P: FnMut(&T) -> bool {
908 fn next_back(&mut self) -> Option<&'a [T]> {
909 if self.finished { return None; }
911 match self.v.iter().rposition(|x| (self.pred)(x)) {
912 None => self.finish(),
914 let ret = Some(&self.v[idx + 1..]);
915 self.v = &self.v[..idx];
922 impl<'a, T, P> SplitIter for Split<'a, T, P> where P: FnMut(&T) -> bool {
924 fn finish(&mut self) -> Option<&'a [T]> {
925 if self.finished { None } else { self.finished = true; Some(self.v) }
929 /// An iterator over the subslices of the vector which are separated
930 /// by elements that match `pred`.
931 #[stable(feature = "rust1", since = "1.0.0")]
932 pub struct SplitMut<'a, T:'a, P> where P: FnMut(&T) -> bool {
938 impl<'a, T, P> SplitIter for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {
940 fn finish(&mut self) -> Option<&'a mut [T]> {
944 self.finished = true;
945 Some(mem::replace(&mut self.v, &mut []))
950 #[stable(feature = "rust1", since = "1.0.0")]
951 impl<'a, T, P> Iterator for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {
952 type Item = &'a mut [T];
955 fn next(&mut self) -> Option<&'a mut [T]> {
956 if self.finished { return None; }
958 let idx_opt = { // work around borrowck limitations
959 let pred = &mut self.pred;
960 self.v.iter().position(|x| (*pred)(x))
963 None => self.finish(),
965 let tmp = mem::replace(&mut self.v, &mut []);
966 let (head, tail) = tmp.split_at_mut(idx);
967 self.v = &mut tail[1..];
974 fn size_hint(&self) -> (usize, Option<usize>) {
978 // if the predicate doesn't match anything, we yield one slice
979 // if it matches every element, we yield len+1 empty slices.
980 (1, Some(self.v.len() + 1))
985 #[stable(feature = "rust1", since = "1.0.0")]
986 impl<'a, T, P> DoubleEndedIterator for SplitMut<'a, T, P> where
987 P: FnMut(&T) -> bool,
990 fn next_back(&mut self) -> Option<&'a mut [T]> {
991 if self.finished { return None; }
993 let idx_opt = { // work around borrowck limitations
994 let pred = &mut self.pred;
995 self.v.iter().rposition(|x| (*pred)(x))
998 None => self.finish(),
1000 let tmp = mem::replace(&mut self.v, &mut []);
1001 let (head, tail) = tmp.split_at_mut(idx);
1003 Some(&mut tail[1..])
1009 /// An private iterator over subslices separated by elements that
1010 /// match a predicate function, splitting at most a fixed number of
1012 struct GenericSplitN<I> {
1018 impl<T, I: SplitIter<Item=T>> Iterator for GenericSplitN<I> {
1022 fn next(&mut self) -> Option<T> {
1025 1 => { self.count -= 1; self.iter.finish() }
1028 if self.invert {self.iter.next_back()} else {self.iter.next()}
1034 fn size_hint(&self) -> (usize, Option<usize>) {
1035 let (lower, upper_opt) = self.iter.size_hint();
1036 (lower, upper_opt.map(|upper| cmp::min(self.count, upper)))
1040 /// An iterator over subslices separated by elements that match a predicate
1041 /// function, limited to a given number of splits.
1042 #[stable(feature = "rust1", since = "1.0.0")]
1043 pub struct SplitN<'a, T: 'a, P> where P: FnMut(&T) -> bool {
1044 inner: GenericSplitN<Split<'a, T, P>>
1047 /// An iterator over subslices separated by elements that match a
1048 /// predicate function, limited to a given number of splits, starting
1049 /// from the end of the slice.
1050 #[stable(feature = "rust1", since = "1.0.0")]
1051 pub struct RSplitN<'a, T: 'a, P> where P: FnMut(&T) -> bool {
1052 inner: GenericSplitN<Split<'a, T, P>>
1055 /// An iterator over subslices separated by elements that match a predicate
1056 /// function, limited to a given number of splits.
1057 #[stable(feature = "rust1", since = "1.0.0")]
1058 pub struct SplitNMut<'a, T: 'a, P> where P: FnMut(&T) -> bool {
1059 inner: GenericSplitN<SplitMut<'a, T, P>>
1062 /// An iterator over subslices separated by elements that match a
1063 /// predicate function, limited to a given number of splits, starting
1064 /// from the end of the slice.
1065 #[stable(feature = "rust1", since = "1.0.0")]
1066 pub struct RSplitNMut<'a, T: 'a, P> where P: FnMut(&T) -> bool {
1067 inner: GenericSplitN<SplitMut<'a, T, P>>
1070 macro_rules! forward_iterator {
1071 ($name:ident: $elem:ident, $iter_of:ty) => {
1072 #[stable(feature = "rust1", since = "1.0.0")]
1073 impl<'a, $elem, P> Iterator for $name<'a, $elem, P> where
1074 P: FnMut(&T) -> bool
1076 type Item = $iter_of;
1079 fn next(&mut self) -> Option<$iter_of> {
1084 fn size_hint(&self) -> (usize, Option<usize>) {
1085 self.inner.size_hint()
1091 forward_iterator! { SplitN: T, &'a [T] }
1092 forward_iterator! { RSplitN: T, &'a [T] }
1093 forward_iterator! { SplitNMut: T, &'a mut [T] }
1094 forward_iterator! { RSplitNMut: T, &'a mut [T] }
1096 /// An iterator over overlapping subslices of length `size`.
1097 #[stable(feature = "rust1", since = "1.0.0")]
1098 pub struct Windows<'a, T:'a> {
1103 // FIXME(#19839) Remove in favor of `#[derive(Clone)]`
1104 #[stable(feature = "rust1", since = "1.0.0")]
1105 impl<'a, T> Clone for Windows<'a, T> {
1106 fn clone(&self) -> Windows<'a, T> {
1114 #[stable(feature = "rust1", since = "1.0.0")]
1115 impl<'a, T> Iterator for Windows<'a, T> {
1116 type Item = &'a [T];
1119 fn next(&mut self) -> Option<&'a [T]> {
1120 if self.size > self.v.len() {
1123 let ret = Some(&self.v[..self.size]);
1124 self.v = &self.v[1..];
1130 fn size_hint(&self) -> (usize, Option<usize>) {
1131 if self.size > self.v.len() {
1134 let size = self.v.len() - self.size + 1;
1140 fn count(self) -> usize {
1145 fn nth(&mut self, n: usize) -> Option<Self::Item> {
1146 let (end, overflow) = self.size.overflowing_add(n);
1147 if end > self.v.len() || overflow {
1151 let nth = &self.v[n..end];
1152 self.v = &self.v[n+1..];
1158 fn last(self) -> Option<Self::Item> {
1159 if self.size > self.v.len() {
1162 let start = self.v.len() - self.size;
1163 Some(&self.v[start..])
1168 #[stable(feature = "rust1", since = "1.0.0")]
1169 impl<'a, T> DoubleEndedIterator for Windows<'a, T> {
1171 fn next_back(&mut self) -> Option<&'a [T]> {
1172 if self.size > self.v.len() {
1175 let ret = Some(&self.v[self.v.len()-self.size..]);
1176 self.v = &self.v[..self.v.len()-1];
1182 #[stable(feature = "rust1", since = "1.0.0")]
1183 impl<'a, T> ExactSizeIterator for Windows<'a, T> {}
1185 /// An iterator over a slice in (non-overlapping) chunks (`size` elements at a
1188 /// When the slice len is not evenly divided by the chunk size, the last slice
1189 /// of the iteration will be the remainder.
1190 #[stable(feature = "rust1", since = "1.0.0")]
1191 pub struct Chunks<'a, T:'a> {
1196 // FIXME(#19839) Remove in favor of `#[derive(Clone)]`
1197 #[stable(feature = "rust1", since = "1.0.0")]
1198 impl<'a, T> Clone for Chunks<'a, T> {
1199 fn clone(&self) -> Chunks<'a, T> {
1207 #[stable(feature = "rust1", since = "1.0.0")]
1208 impl<'a, T> Iterator for Chunks<'a, T> {
1209 type Item = &'a [T];
1212 fn next(&mut self) -> Option<&'a [T]> {
1213 if self.v.is_empty() {
1216 let chunksz = cmp::min(self.v.len(), self.size);
1217 let (fst, snd) = self.v.split_at(chunksz);
1224 fn size_hint(&self) -> (usize, Option<usize>) {
1225 if self.v.is_empty() {
1228 let n = self.v.len() / self.size;
1229 let rem = self.v.len() % self.size;
1230 let n = if rem > 0 { n+1 } else { n };
1236 fn count(self) -> usize {
1241 fn nth(&mut self, n: usize) -> Option<Self::Item> {
1242 let (start, overflow) = n.overflowing_mul(self.size);
1243 if start >= self.v.len() || overflow {
1247 let end = match start.checked_add(self.size) {
1248 Some(sum) => cmp::min(self.v.len(), sum),
1249 None => self.v.len(),
1251 let nth = &self.v[start..end];
1252 self.v = &self.v[end..];
1258 fn last(self) -> Option<Self::Item> {
1259 if self.v.is_empty() {
1262 let start = (self.v.len() - 1) / self.size * self.size;
1263 Some(&self.v[start..])
1268 #[stable(feature = "rust1", since = "1.0.0")]
1269 impl<'a, T> DoubleEndedIterator for Chunks<'a, T> {
1271 fn next_back(&mut self) -> Option<&'a [T]> {
1272 if self.v.is_empty() {
1275 let remainder = self.v.len() % self.size;
1276 let chunksz = if remainder != 0 { remainder } else { self.size };
1277 let (fst, snd) = self.v.split_at(self.v.len() - chunksz);
1284 #[stable(feature = "rust1", since = "1.0.0")]
1285 impl<'a, T> ExactSizeIterator for Chunks<'a, T> {}
1287 /// An iterator over a slice in (non-overlapping) mutable chunks (`size`
1288 /// elements at a time). When the slice len is not evenly divided by the chunk
1289 /// size, the last slice of the iteration will be the remainder.
1290 #[stable(feature = "rust1", since = "1.0.0")]
1291 pub struct ChunksMut<'a, T:'a> {
1296 #[stable(feature = "rust1", since = "1.0.0")]
1297 impl<'a, T> Iterator for ChunksMut<'a, T> {
1298 type Item = &'a mut [T];
1301 fn next(&mut self) -> Option<&'a mut [T]> {
1302 if self.v.is_empty() {
1305 let sz = cmp::min(self.v.len(), self.chunk_size);
1306 let tmp = mem::replace(&mut self.v, &mut []);
1307 let (head, tail) = tmp.split_at_mut(sz);
1314 fn size_hint(&self) -> (usize, Option<usize>) {
1315 if self.v.is_empty() {
1318 let n = self.v.len() / self.chunk_size;
1319 let rem = self.v.len() % self.chunk_size;
1320 let n = if rem > 0 { n + 1 } else { n };
1326 fn count(self) -> usize {
1331 fn nth(&mut self, n: usize) -> Option<&'a mut [T]> {
1332 let (start, overflow) = n.overflowing_mul(self.chunk_size);
1333 if start >= self.v.len() || overflow {
1337 let end = match start.checked_add(self.chunk_size) {
1338 Some(sum) => cmp::min(self.v.len(), sum),
1339 None => self.v.len(),
1341 let tmp = mem::replace(&mut self.v, &mut []);
1342 let (head, tail) = tmp.split_at_mut(end);
1343 let (_, nth) = head.split_at_mut(start);
1350 fn last(self) -> Option<Self::Item> {
1351 if self.v.is_empty() {
1354 let start = (self.v.len() - 1) / self.chunk_size * self.chunk_size;
1355 Some(&mut self.v[start..])
1360 #[stable(feature = "rust1", since = "1.0.0")]
1361 impl<'a, T> DoubleEndedIterator for ChunksMut<'a, T> {
1363 fn next_back(&mut self) -> Option<&'a mut [T]> {
1364 if self.v.is_empty() {
1367 let remainder = self.v.len() % self.chunk_size;
1368 let sz = if remainder != 0 { remainder } else { self.chunk_size };
1369 let tmp = mem::replace(&mut self.v, &mut []);
1370 let tmp_len = tmp.len();
1371 let (head, tail) = tmp.split_at_mut(tmp_len - sz);
1378 #[stable(feature = "rust1", since = "1.0.0")]
1379 impl<'a, T> ExactSizeIterator for ChunksMut<'a, T> {}
1385 /// Forms a slice from a pointer and a length.
1387 /// The `len` argument is the number of **elements**, not the number of bytes.
1391 /// This function is unsafe as there is no guarantee that the given pointer is
1392 /// valid for `len` elements, nor whether the lifetime inferred is a suitable
1393 /// lifetime for the returned slice.
1395 /// `p` must be non-null, even for zero-length slices.
1399 /// The lifetime for the returned slice is inferred from its usage. To
1400 /// prevent accidental misuse, it's suggested to tie the lifetime to whichever
1401 /// source lifetime is safe in the context, such as by providing a helper
1402 /// function taking the lifetime of a host value for the slice, or by explicit
1410 /// // manifest a slice out of thin air!
1411 /// let ptr = 0x1234 as *const usize;
1414 /// let slice = slice::from_raw_parts(ptr, amt);
1418 #[stable(feature = "rust1", since = "1.0.0")]
1419 pub unsafe fn from_raw_parts<'a, T>(p: *const T, len: usize) -> &'a [T] {
1420 mem::transmute(RawSlice { data: p, len: len })
1423 /// Performs the same functionality as `from_raw_parts`, except that a mutable
1424 /// slice is returned.
1426 /// This function is unsafe for the same reasons as `from_raw_parts`, as well
1427 /// as not being able to provide a non-aliasing guarantee of the returned
1430 #[stable(feature = "rust1", since = "1.0.0")]
1431 pub unsafe fn from_raw_parts_mut<'a, T>(p: *mut T, len: usize) -> &'a mut [T] {
1432 mem::transmute(RawSlice { data: p, len: len })
1439 /// Operations on `[u8]`.
1440 #[unstable(feature = "slice_bytes", reason = "needs review",
1442 #[rustc_deprecated(reason = "unidiomatic functions not pulling their weight",
1444 #[allow(deprecated)]
1447 use slice::SliceExt;
1449 /// A trait for operations on mutable `[u8]`s.
1450 pub trait MutableByteVector {
1451 /// Sets all bytes of the receiver to the given value.
1452 fn set_memory(&mut self, value: u8);
1455 impl MutableByteVector for [u8] {
1457 fn set_memory(&mut self, value: u8) {
1458 unsafe { ptr::write_bytes(self.as_mut_ptr(), value, self.len()) };
1462 /// Copies data from `src` to `dst`
1464 /// Panics if the length of `dst` is less than the length of `src`.
1466 pub fn copy_memory(src: &[u8], dst: &mut [u8]) {
1467 let len_src = src.len();
1468 assert!(dst.len() >= len_src);
1469 // `dst` is unaliasable, so we know statically it doesn't overlap
1472 ptr::copy_nonoverlapping(src.as_ptr(),
1482 // Boilerplate traits
1485 #[stable(feature = "rust1", since = "1.0.0")]
1486 impl<A, B> PartialEq<[B]> for [A] where A: PartialEq<B> {
1487 fn eq(&self, other: &[B]) -> bool {
1488 if self.len() != other.len() {
1492 for i in 0..self.len() {
1493 if !self[i].eq(&other[i]) {
1500 fn ne(&self, other: &[B]) -> bool {
1501 if self.len() != other.len() {
1505 for i in 0..self.len() {
1506 if self[i].ne(&other[i]) {
1515 #[stable(feature = "rust1", since = "1.0.0")]
1516 impl<T: Eq> Eq for [T] {}
1518 #[stable(feature = "rust1", since = "1.0.0")]
1519 impl<T: Ord> Ord for [T] {
1520 fn cmp(&self, other: &[T]) -> Ordering {
1521 let l = cmp::min(self.len(), other.len());
1523 // Slice to the loop iteration range to enable bound check
1524 // elimination in the compiler
1525 let lhs = &self[..l];
1526 let rhs = &other[..l];
1529 match lhs[i].cmp(&rhs[i]) {
1530 Ordering::Equal => (),
1531 non_eq => return non_eq,
1535 self.len().cmp(&other.len())
1539 #[stable(feature = "rust1", since = "1.0.0")]
1540 impl<T: PartialOrd> PartialOrd for [T] {
1541 fn partial_cmp(&self, other: &[T]) -> Option<Ordering> {
1542 let l = cmp::min(self.len(), other.len());
1544 // Slice to the loop iteration range to enable bound check
1545 // elimination in the compiler
1546 let lhs = &self[..l];
1547 let rhs = &other[..l];
1550 match lhs[i].partial_cmp(&rhs[i]) {
1551 Some(Ordering::Equal) => (),
1552 non_eq => return non_eq,
1556 self.len().partial_cmp(&other.len())