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 : usize = 0;
298 let mut lim : usize = self.len();
301 let ix = base + (lim >> 1);
303 Equal => return Ok(ix),
316 fn len(&self) -> usize { self.repr().len }
319 fn get_mut(&mut self, index: usize) -> Option<&mut T> {
320 if index < self.len() { Some(&mut self[index]) } else { None }
324 fn split_at_mut(&mut self, mid: usize) -> (&mut [T], &mut [T]) {
325 let len = self.len();
326 let ptr = self.as_mut_ptr();
331 (from_raw_parts_mut(ptr, mid),
332 from_raw_parts_mut(ptr.offset(mid as isize), len - mid))
337 fn iter_mut(&mut self) -> IterMut<T> {
339 let p = if mem::size_of::<T>() == 0 {
342 let p = self.as_mut_ptr();
343 assume(!p.is_null());
349 end: slice_offset!(p, self.len() as isize),
350 _marker: marker::PhantomData
356 fn last_mut(&mut self) -> Option<&mut T> {
357 let len = self.len();
358 if len == 0 { return None; }
359 Some(&mut self[len - 1])
363 fn first_mut(&mut self) -> Option<&mut T> {
364 if self.is_empty() { None } else { Some(&mut self[0]) }
368 fn split_first_mut(&mut self) -> Option<(&mut T, &mut [T])> {
369 if self.is_empty() { None } else {
370 let split = self.split_at_mut(1);
371 Some((&mut split.0[0], split.1))
376 fn split_last_mut(&mut self) -> Option<(&mut T, &mut [T])> {
377 let len = self.len();
378 if len == 0 { None } else {
379 let split = self.split_at_mut(len - 1);
380 Some((&mut split.1[0], split.0))
385 fn split_mut<P>(&mut self, pred: P) -> SplitMut<T, P> where P: FnMut(&T) -> bool {
386 SplitMut { v: self, pred: pred, finished: false }
390 fn splitn_mut<P>(&mut self, n: usize, pred: P) -> SplitNMut<T, P> where
394 inner: GenericSplitN {
395 iter: self.split_mut(pred),
403 fn rsplitn_mut<P>(&mut self, n: usize, pred: P) -> RSplitNMut<T, P> where
404 P: FnMut(&T) -> bool,
407 inner: GenericSplitN {
408 iter: self.split_mut(pred),
416 fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<T> {
417 assert!(chunk_size > 0);
418 ChunksMut { v: self, chunk_size: chunk_size }
422 fn swap(&mut self, a: usize, b: usize) {
424 // Can't take two mutable loans from one vector, so instead just cast
425 // them to their raw pointers to do the swap
426 let pa: *mut T = &mut self[a];
427 let pb: *mut T = &mut self[b];
432 fn reverse(&mut self) {
433 let mut i: usize = 0;
436 // Unsafe swap to avoid the bounds check in safe swap.
438 let pa: *mut T = self.get_unchecked_mut(i);
439 let pb: *mut T = self.get_unchecked_mut(ln - i - 1);
447 unsafe fn get_unchecked_mut(&mut self, index: usize) -> &mut T {
448 &mut *(self.repr().data as *mut T).offset(index as isize)
452 fn as_mut_ptr(&mut self) -> *mut T {
453 self.repr().data as *mut T
457 fn contains(&self, x: &T) -> bool where T: PartialEq {
458 self.iter().any(|elt| *x == *elt)
462 fn starts_with(&self, needle: &[T]) -> bool where T: PartialEq {
463 let n = needle.len();
464 self.len() >= n && needle == &self[..n]
468 fn ends_with(&self, needle: &[T]) -> bool where T: PartialEq {
469 let (m, n) = (self.len(), needle.len());
470 m >= n && needle == &self[m-n..]
473 fn binary_search(&self, x: &T) -> Result<usize, usize> where T: Ord {
474 self.binary_search_by(|p| p.cmp(x))
478 fn clone_from_slice(&mut self, src: &[T]) where T: Clone {
479 assert!(self.len() == src.len(),
480 "destination and source slices have different lengths");
481 // NOTE: We need to explicitly slice them to the same length
482 // for bounds checking to be elided, and the optimizer will
483 // generate memcpy for simple cases (for example T = u8).
484 let len = self.len();
485 let src = &src[..len];
487 self[i].clone_from(&src[i]);
492 #[stable(feature = "rust1", since = "1.0.0")]
493 impl<T> ops::Index<usize> for [T] {
496 fn index(&self, index: usize) -> &T {
497 assert!(index < self.len());
498 unsafe { self.get_unchecked(index) }
502 #[stable(feature = "rust1", since = "1.0.0")]
503 impl<T> ops::IndexMut<usize> for [T] {
505 fn index_mut(&mut self, index: usize) -> &mut T {
506 assert!(index < self.len());
507 unsafe { self.get_unchecked_mut(index) }
513 fn slice_index_len_fail(index: usize, len: usize) -> ! {
514 panic!("index {} out of range for slice of length {}", index, len);
519 fn slice_index_order_fail(index: usize, end: usize) -> ! {
520 panic!("slice index starts at {} but ends at {}", index, end);
523 #[stable(feature = "rust1", since = "1.0.0")]
524 impl<T> ops::Index<ops::Range<usize>> for [T] {
528 fn index(&self, index: ops::Range<usize>) -> &[T] {
529 if index.start > index.end {
530 slice_index_order_fail(index.start, index.end);
531 } else if index.end > self.len() {
532 slice_index_len_fail(index.end, self.len());
536 self.as_ptr().offset(index.start as isize),
537 index.end - index.start
542 #[stable(feature = "rust1", since = "1.0.0")]
543 impl<T> ops::Index<ops::RangeTo<usize>> for [T] {
547 fn index(&self, index: ops::RangeTo<usize>) -> &[T] {
548 self.index(ops::Range{ start: 0, end: index.end })
551 #[stable(feature = "rust1", since = "1.0.0")]
552 impl<T> ops::Index<ops::RangeFrom<usize>> for [T] {
556 fn index(&self, index: ops::RangeFrom<usize>) -> &[T] {
557 self.index(ops::Range{ start: index.start, end: self.len() })
560 #[stable(feature = "rust1", since = "1.0.0")]
561 impl<T> ops::Index<RangeFull> for [T] {
565 fn index(&self, _index: RangeFull) -> &[T] {
570 #[stable(feature = "rust1", since = "1.0.0")]
571 impl<T> ops::IndexMut<ops::Range<usize>> for [T] {
573 fn index_mut(&mut self, index: ops::Range<usize>) -> &mut [T] {
574 if index.start > index.end {
575 slice_index_order_fail(index.start, index.end);
576 } else if index.end > self.len() {
577 slice_index_len_fail(index.end, self.len());
581 self.as_mut_ptr().offset(index.start as isize),
582 index.end - index.start
587 #[stable(feature = "rust1", since = "1.0.0")]
588 impl<T> ops::IndexMut<ops::RangeTo<usize>> for [T] {
590 fn index_mut(&mut self, index: ops::RangeTo<usize>) -> &mut [T] {
591 self.index_mut(ops::Range{ start: 0, end: index.end })
594 #[stable(feature = "rust1", since = "1.0.0")]
595 impl<T> ops::IndexMut<ops::RangeFrom<usize>> for [T] {
597 fn index_mut(&mut self, index: ops::RangeFrom<usize>) -> &mut [T] {
598 let len = self.len();
599 self.index_mut(ops::Range{ start: index.start, end: len })
602 #[stable(feature = "rust1", since = "1.0.0")]
603 impl<T> ops::IndexMut<RangeFull> for [T] {
605 fn index_mut(&mut self, _index: RangeFull) -> &mut [T] {
611 ////////////////////////////////////////////////////////////////////////////////
613 ////////////////////////////////////////////////////////////////////////////////
615 #[stable(feature = "rust1", since = "1.0.0")]
616 impl<'a, T> Default for &'a [T] {
617 fn default() -> &'a [T] { &[] }
620 #[stable(feature = "mut_slice_default", since = "1.5.0")]
621 impl<'a, T> Default for &'a mut [T] {
622 fn default() -> &'a mut [T] { &mut [] }
629 #[stable(feature = "rust1", since = "1.0.0")]
630 impl<'a, T> IntoIterator for &'a [T] {
632 type IntoIter = Iter<'a, T>;
634 fn into_iter(self) -> Iter<'a, T> {
639 #[stable(feature = "rust1", since = "1.0.0")]
640 impl<'a, T> IntoIterator for &'a mut [T] {
641 type Item = &'a mut T;
642 type IntoIter = IterMut<'a, T>;
644 fn into_iter(self) -> IterMut<'a, T> {
650 fn size_from_ptr<T>(_: *const T) -> usize {
654 // The shared definition of the `Iter` and `IterMut` iterators
655 macro_rules! iterator {
656 (struct $name:ident -> $ptr:ty, $elem:ty) => {
657 #[stable(feature = "rust1", since = "1.0.0")]
658 impl<'a, T> Iterator for $name<'a, T> {
662 fn next(&mut self) -> Option<$elem> {
663 // could be implemented with slices, but this avoids bounds checks
665 if mem::size_of::<T>() != 0 {
666 assume(!self.ptr.is_null());
667 assume(!self.end.is_null());
669 if self.ptr == self.end {
673 self.ptr = slice_offset!(self.ptr, 1);
674 Some(slice_ref!(old))
680 fn size_hint(&self) -> (usize, Option<usize>) {
681 let diff = (self.end as usize).wrapping_sub(self.ptr as usize);
682 let size = mem::size_of::<T>();
683 let exact = diff / (if size == 0 {1} else {size});
688 fn count(self) -> usize {
693 fn nth(&mut self, n: usize) -> Option<$elem> {
694 // Call helper method. Can't put the definition here because mut versus const.
699 fn last(mut self) -> Option<$elem> {
704 #[stable(feature = "rust1", since = "1.0.0")]
705 impl<'a, T> DoubleEndedIterator for $name<'a, T> {
707 fn next_back(&mut self) -> Option<$elem> {
708 // could be implemented with slices, but this avoids bounds checks
710 if mem::size_of::<T>() != 0 {
711 assume(!self.ptr.is_null());
712 assume(!self.end.is_null());
714 if self.end == self.ptr {
717 self.end = slice_offset!(self.end, -1);
718 Some(slice_ref!(self.end))
726 macro_rules! make_slice {
727 ($start: expr, $end: expr) => {{
729 let diff = ($end as usize).wrapping_sub(start as usize);
730 if size_from_ptr(start) == 0 {
731 // use a non-null pointer value
732 unsafe { from_raw_parts(1 as *const _, diff) }
734 let len = diff / size_from_ptr(start);
735 unsafe { from_raw_parts(start, len) }
740 macro_rules! make_mut_slice {
741 ($start: expr, $end: expr) => {{
743 let diff = ($end as usize).wrapping_sub(start as usize);
744 if size_from_ptr(start) == 0 {
745 // use a non-null pointer value
746 unsafe { from_raw_parts_mut(1 as *mut _, diff) }
748 let len = diff / size_from_ptr(start);
749 unsafe { from_raw_parts_mut(start, len) }
754 /// Immutable slice iterator
755 #[stable(feature = "rust1", since = "1.0.0")]
756 pub struct Iter<'a, T: 'a> {
759 _marker: marker::PhantomData<&'a T>,
762 #[stable(feature = "rust1", since = "1.0.0")]
763 unsafe impl<'a, T: Sync> Sync for Iter<'a, T> {}
764 #[stable(feature = "rust1", since = "1.0.0")]
765 unsafe impl<'a, T: Sync> Send for Iter<'a, T> {}
767 impl<'a, T> Iter<'a, T> {
768 /// View the underlying data as a subslice of the original data.
770 /// This has the same lifetime as the original slice, and so the
771 /// iterator can continue to be used while this exists.
772 #[stable(feature = "iter_to_slice", since = "1.4.0")]
773 pub fn as_slice(&self) -> &'a [T] {
774 make_slice!(self.ptr, self.end)
777 // Helper function for Iter::nth
778 fn iter_nth(&mut self, n: usize) -> Option<&'a T> {
779 match self.as_slice().get(n) {
780 Some(elem_ref) => unsafe {
781 self.ptr = slice_offset!(self.ptr, (n as isize).wrapping_add(1));
792 iterator!{struct Iter -> *const T, &'a T}
794 #[stable(feature = "rust1", since = "1.0.0")]
795 impl<'a, T> ExactSizeIterator for Iter<'a, T> {}
797 #[stable(feature = "rust1", since = "1.0.0")]
798 impl<'a, T> Clone for Iter<'a, T> {
799 fn clone(&self) -> Iter<'a, T> { Iter { ptr: self.ptr, end: self.end, _marker: self._marker } }
802 /// Mutable slice iterator.
803 #[stable(feature = "rust1", since = "1.0.0")]
804 pub struct IterMut<'a, T: 'a> {
807 _marker: marker::PhantomData<&'a mut T>,
810 #[stable(feature = "rust1", since = "1.0.0")]
811 unsafe impl<'a, T: Sync> Sync for IterMut<'a, T> {}
812 #[stable(feature = "rust1", since = "1.0.0")]
813 unsafe impl<'a, T: Send> Send for IterMut<'a, T> {}
815 impl<'a, T> IterMut<'a, T> {
816 /// View the underlying data as a subslice of the original data.
818 /// To avoid creating `&mut` references that alias, this is forced
819 /// to consume the iterator. Consider using the `Slice` and
820 /// `SliceMut` implementations for obtaining slices with more
821 /// restricted lifetimes that do not consume the iterator.
822 #[stable(feature = "iter_to_slice", since = "1.4.0")]
823 pub fn into_slice(self) -> &'a mut [T] {
824 make_mut_slice!(self.ptr, self.end)
827 // Helper function for IterMut::nth
828 fn iter_nth(&mut self, n: usize) -> Option<&'a mut T> {
829 match make_mut_slice!(self.ptr, self.end).get_mut(n) {
830 Some(elem_ref) => unsafe {
831 self.ptr = slice_offset!(self.ptr, (n as isize).wrapping_add(1));
842 iterator!{struct IterMut -> *mut T, &'a mut T}
844 #[stable(feature = "rust1", since = "1.0.0")]
845 impl<'a, T> ExactSizeIterator for IterMut<'a, T> {}
847 /// An internal abstraction over the splitting iterators, so that
848 /// splitn, splitn_mut etc can be implemented once.
849 trait SplitIter: DoubleEndedIterator {
850 /// Mark the underlying iterator as complete, extracting the remaining
851 /// portion of the slice.
852 fn finish(&mut self) -> Option<Self::Item>;
855 /// An iterator over subslices separated by elements that match a predicate
857 #[stable(feature = "rust1", since = "1.0.0")]
858 pub struct Split<'a, T:'a, P> where P: FnMut(&T) -> bool {
864 // FIXME(#19839) Remove in favor of `#[derive(Clone)]`
865 #[stable(feature = "rust1", since = "1.0.0")]
866 impl<'a, T, P> Clone for Split<'a, T, P> where P: Clone + FnMut(&T) -> bool {
867 fn clone(&self) -> Split<'a, T, P> {
870 pred: self.pred.clone(),
871 finished: self.finished,
876 #[stable(feature = "rust1", since = "1.0.0")]
877 impl<'a, T, P> Iterator for Split<'a, T, P> where P: FnMut(&T) -> bool {
881 fn next(&mut self) -> Option<&'a [T]> {
882 if self.finished { return None; }
884 match self.v.iter().position(|x| (self.pred)(x)) {
885 None => self.finish(),
887 let ret = Some(&self.v[..idx]);
888 self.v = &self.v[idx + 1..];
895 fn size_hint(&self) -> (usize, Option<usize>) {
899 (1, Some(self.v.len() + 1))
904 #[stable(feature = "rust1", since = "1.0.0")]
905 impl<'a, T, P> DoubleEndedIterator for Split<'a, T, P> where P: FnMut(&T) -> bool {
907 fn next_back(&mut self) -> Option<&'a [T]> {
908 if self.finished { return None; }
910 match self.v.iter().rposition(|x| (self.pred)(x)) {
911 None => self.finish(),
913 let ret = Some(&self.v[idx + 1..]);
914 self.v = &self.v[..idx];
921 impl<'a, T, P> SplitIter for Split<'a, T, P> where P: FnMut(&T) -> bool {
923 fn finish(&mut self) -> Option<&'a [T]> {
924 if self.finished { None } else { self.finished = true; Some(self.v) }
928 /// An iterator over the subslices of the vector which are separated
929 /// by elements that match `pred`.
930 #[stable(feature = "rust1", since = "1.0.0")]
931 pub struct SplitMut<'a, T:'a, P> where P: FnMut(&T) -> bool {
937 impl<'a, T, P> SplitIter for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {
939 fn finish(&mut self) -> Option<&'a mut [T]> {
943 self.finished = true;
944 Some(mem::replace(&mut self.v, &mut []))
949 #[stable(feature = "rust1", since = "1.0.0")]
950 impl<'a, T, P> Iterator for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {
951 type Item = &'a mut [T];
954 fn next(&mut self) -> Option<&'a mut [T]> {
955 if self.finished { return None; }
957 let idx_opt = { // work around borrowck limitations
958 let pred = &mut self.pred;
959 self.v.iter().position(|x| (*pred)(x))
962 None => self.finish(),
964 let tmp = mem::replace(&mut self.v, &mut []);
965 let (head, tail) = tmp.split_at_mut(idx);
966 self.v = &mut tail[1..];
973 fn size_hint(&self) -> (usize, Option<usize>) {
977 // if the predicate doesn't match anything, we yield one slice
978 // if it matches every element, we yield len+1 empty slices.
979 (1, Some(self.v.len() + 1))
984 #[stable(feature = "rust1", since = "1.0.0")]
985 impl<'a, T, P> DoubleEndedIterator for SplitMut<'a, T, P> where
986 P: FnMut(&T) -> bool,
989 fn next_back(&mut self) -> Option<&'a mut [T]> {
990 if self.finished { return None; }
992 let idx_opt = { // work around borrowck limitations
993 let pred = &mut self.pred;
994 self.v.iter().rposition(|x| (*pred)(x))
997 None => self.finish(),
999 let tmp = mem::replace(&mut self.v, &mut []);
1000 let (head, tail) = tmp.split_at_mut(idx);
1002 Some(&mut tail[1..])
1008 /// An private iterator over subslices separated by elements that
1009 /// match a predicate function, splitting at most a fixed number of
1011 struct GenericSplitN<I> {
1017 impl<T, I: SplitIter<Item=T>> Iterator for GenericSplitN<I> {
1021 fn next(&mut self) -> Option<T> {
1024 1 => { self.count -= 1; self.iter.finish() }
1027 if self.invert {self.iter.next_back()} else {self.iter.next()}
1033 fn size_hint(&self) -> (usize, Option<usize>) {
1034 let (lower, upper_opt) = self.iter.size_hint();
1035 (lower, upper_opt.map(|upper| cmp::min(self.count, upper)))
1039 /// An iterator over subslices separated by elements that match a predicate
1040 /// function, limited to a given number of splits.
1041 #[stable(feature = "rust1", since = "1.0.0")]
1042 pub struct SplitN<'a, T: 'a, P> where P: FnMut(&T) -> bool {
1043 inner: GenericSplitN<Split<'a, T, P>>
1046 /// An iterator over subslices separated by elements that match a
1047 /// predicate function, limited to a given number of splits, starting
1048 /// from the end of the slice.
1049 #[stable(feature = "rust1", since = "1.0.0")]
1050 pub struct RSplitN<'a, T: 'a, P> where P: FnMut(&T) -> bool {
1051 inner: GenericSplitN<Split<'a, T, P>>
1054 /// An iterator over subslices separated by elements that match a predicate
1055 /// function, limited to a given number of splits.
1056 #[stable(feature = "rust1", since = "1.0.0")]
1057 pub struct SplitNMut<'a, T: 'a, P> where P: FnMut(&T) -> bool {
1058 inner: GenericSplitN<SplitMut<'a, T, P>>
1061 /// An iterator over subslices separated by elements that match a
1062 /// predicate function, limited to a given number of splits, starting
1063 /// from the end of the slice.
1064 #[stable(feature = "rust1", since = "1.0.0")]
1065 pub struct RSplitNMut<'a, T: 'a, P> where P: FnMut(&T) -> bool {
1066 inner: GenericSplitN<SplitMut<'a, T, P>>
1069 macro_rules! forward_iterator {
1070 ($name:ident: $elem:ident, $iter_of:ty) => {
1071 #[stable(feature = "rust1", since = "1.0.0")]
1072 impl<'a, $elem, P> Iterator for $name<'a, $elem, P> where
1073 P: FnMut(&T) -> bool
1075 type Item = $iter_of;
1078 fn next(&mut self) -> Option<$iter_of> {
1083 fn size_hint(&self) -> (usize, Option<usize>) {
1084 self.inner.size_hint()
1090 forward_iterator! { SplitN: T, &'a [T] }
1091 forward_iterator! { RSplitN: T, &'a [T] }
1092 forward_iterator! { SplitNMut: T, &'a mut [T] }
1093 forward_iterator! { RSplitNMut: T, &'a mut [T] }
1095 /// An iterator over overlapping subslices of length `size`.
1096 #[stable(feature = "rust1", since = "1.0.0")]
1097 pub struct Windows<'a, T:'a> {
1102 // FIXME(#19839) Remove in favor of `#[derive(Clone)]`
1103 #[stable(feature = "rust1", since = "1.0.0")]
1104 impl<'a, T> Clone for Windows<'a, T> {
1105 fn clone(&self) -> Windows<'a, T> {
1113 #[stable(feature = "rust1", since = "1.0.0")]
1114 impl<'a, T> Iterator for Windows<'a, T> {
1115 type Item = &'a [T];
1118 fn next(&mut self) -> Option<&'a [T]> {
1119 if self.size > self.v.len() {
1122 let ret = Some(&self.v[..self.size]);
1123 self.v = &self.v[1..];
1129 fn size_hint(&self) -> (usize, Option<usize>) {
1130 if self.size > self.v.len() {
1133 let size = self.v.len() - self.size + 1;
1139 fn count(self) -> usize {
1144 fn nth(&mut self, n: usize) -> Option<Self::Item> {
1145 let (end, overflow) = self.size.overflowing_add(n);
1146 if end > self.v.len() || overflow {
1150 let nth = &self.v[n..end];
1151 self.v = &self.v[n+1..];
1157 fn last(self) -> Option<Self::Item> {
1158 if self.size > self.v.len() {
1161 let start = self.v.len() - self.size;
1162 Some(&self.v[start..])
1167 #[stable(feature = "rust1", since = "1.0.0")]
1168 impl<'a, T> DoubleEndedIterator for Windows<'a, T> {
1170 fn next_back(&mut self) -> Option<&'a [T]> {
1171 if self.size > self.v.len() {
1174 let ret = Some(&self.v[self.v.len()-self.size..]);
1175 self.v = &self.v[..self.v.len()-1];
1181 #[stable(feature = "rust1", since = "1.0.0")]
1182 impl<'a, T> ExactSizeIterator for Windows<'a, T> {}
1184 /// An iterator over a slice in (non-overlapping) chunks (`size` elements at a
1187 /// When the slice len is not evenly divided by the chunk size, the last slice
1188 /// of the iteration will be the remainder.
1189 #[stable(feature = "rust1", since = "1.0.0")]
1190 pub struct Chunks<'a, T:'a> {
1195 // FIXME(#19839) Remove in favor of `#[derive(Clone)]`
1196 #[stable(feature = "rust1", since = "1.0.0")]
1197 impl<'a, T> Clone for Chunks<'a, T> {
1198 fn clone(&self) -> Chunks<'a, T> {
1206 #[stable(feature = "rust1", since = "1.0.0")]
1207 impl<'a, T> Iterator for Chunks<'a, T> {
1208 type Item = &'a [T];
1211 fn next(&mut self) -> Option<&'a [T]> {
1212 if self.v.is_empty() {
1215 let chunksz = cmp::min(self.v.len(), self.size);
1216 let (fst, snd) = self.v.split_at(chunksz);
1223 fn size_hint(&self) -> (usize, Option<usize>) {
1224 if self.v.is_empty() {
1227 let n = self.v.len() / self.size;
1228 let rem = self.v.len() % self.size;
1229 let n = if rem > 0 { n+1 } else { n };
1235 fn count(self) -> usize {
1240 fn nth(&mut self, n: usize) -> Option<Self::Item> {
1241 let (start, overflow) = n.overflowing_mul(self.size);
1242 if start >= self.v.len() || overflow {
1246 let end = match start.checked_add(self.size) {
1247 Some(sum) => cmp::min(self.v.len(), sum),
1248 None => self.v.len(),
1250 let nth = &self.v[start..end];
1251 self.v = &self.v[end..];
1257 fn last(self) -> Option<Self::Item> {
1258 if self.v.is_empty() {
1261 let start = (self.v.len() - 1) / self.size * self.size;
1262 Some(&self.v[start..])
1267 #[stable(feature = "rust1", since = "1.0.0")]
1268 impl<'a, T> DoubleEndedIterator for Chunks<'a, T> {
1270 fn next_back(&mut self) -> Option<&'a [T]> {
1271 if self.v.is_empty() {
1274 let remainder = self.v.len() % self.size;
1275 let chunksz = if remainder != 0 { remainder } else { self.size };
1276 let (fst, snd) = self.v.split_at(self.v.len() - chunksz);
1283 #[stable(feature = "rust1", since = "1.0.0")]
1284 impl<'a, T> ExactSizeIterator for Chunks<'a, T> {}
1286 /// An iterator over a slice in (non-overlapping) mutable chunks (`size`
1287 /// elements at a time). When the slice len is not evenly divided by the chunk
1288 /// size, the last slice of the iteration will be the remainder.
1289 #[stable(feature = "rust1", since = "1.0.0")]
1290 pub struct ChunksMut<'a, T:'a> {
1295 #[stable(feature = "rust1", since = "1.0.0")]
1296 impl<'a, T> Iterator for ChunksMut<'a, T> {
1297 type Item = &'a mut [T];
1300 fn next(&mut self) -> Option<&'a mut [T]> {
1301 if self.v.is_empty() {
1304 let sz = cmp::min(self.v.len(), self.chunk_size);
1305 let tmp = mem::replace(&mut self.v, &mut []);
1306 let (head, tail) = tmp.split_at_mut(sz);
1313 fn size_hint(&self) -> (usize, Option<usize>) {
1314 if self.v.is_empty() {
1317 let n = self.v.len() / self.chunk_size;
1318 let rem = self.v.len() % self.chunk_size;
1319 let n = if rem > 0 { n + 1 } else { n };
1325 fn count(self) -> usize {
1330 fn nth(&mut self, n: usize) -> Option<&'a mut [T]> {
1331 let (start, overflow) = n.overflowing_mul(self.chunk_size);
1332 if start >= self.v.len() || overflow {
1336 let end = match start.checked_add(self.chunk_size) {
1337 Some(sum) => cmp::min(self.v.len(), sum),
1338 None => self.v.len(),
1340 let tmp = mem::replace(&mut self.v, &mut []);
1341 let (head, tail) = tmp.split_at_mut(end);
1342 let (_, nth) = head.split_at_mut(start);
1349 fn last(self) -> Option<Self::Item> {
1350 if self.v.is_empty() {
1353 let start = (self.v.len() - 1) / self.chunk_size * self.chunk_size;
1354 Some(&mut self.v[start..])
1359 #[stable(feature = "rust1", since = "1.0.0")]
1360 impl<'a, T> DoubleEndedIterator for ChunksMut<'a, T> {
1362 fn next_back(&mut self) -> Option<&'a mut [T]> {
1363 if self.v.is_empty() {
1366 let remainder = self.v.len() % self.chunk_size;
1367 let sz = if remainder != 0 { remainder } else { self.chunk_size };
1368 let tmp = mem::replace(&mut self.v, &mut []);
1369 let tmp_len = tmp.len();
1370 let (head, tail) = tmp.split_at_mut(tmp_len - sz);
1377 #[stable(feature = "rust1", since = "1.0.0")]
1378 impl<'a, T> ExactSizeIterator for ChunksMut<'a, T> {}
1384 /// Forms a slice from a pointer and a length.
1386 /// The `len` argument is the number of **elements**, not the number of bytes.
1390 /// This function is unsafe as there is no guarantee that the given pointer is
1391 /// valid for `len` elements, nor whether the lifetime inferred is a suitable
1392 /// lifetime for the returned slice.
1394 /// `p` must be non-null, even for zero-length slices.
1398 /// The lifetime for the returned slice is inferred from its usage. To
1399 /// prevent accidental misuse, it's suggested to tie the lifetime to whichever
1400 /// source lifetime is safe in the context, such as by providing a helper
1401 /// function taking the lifetime of a host value for the slice, or by explicit
1409 /// // manifest a slice out of thin air!
1410 /// let ptr = 0x1234 as *const usize;
1413 /// let slice = slice::from_raw_parts(ptr, amt);
1417 #[stable(feature = "rust1", since = "1.0.0")]
1418 pub unsafe fn from_raw_parts<'a, T>(p: *const T, len: usize) -> &'a [T] {
1419 mem::transmute(RawSlice { data: p, len: len })
1422 /// Performs the same functionality as `from_raw_parts`, except that a mutable
1423 /// slice is returned.
1425 /// This function is unsafe for the same reasons as `from_raw_parts`, as well
1426 /// as not being able to provide a non-aliasing guarantee of the returned
1429 #[stable(feature = "rust1", since = "1.0.0")]
1430 pub unsafe fn from_raw_parts_mut<'a, T>(p: *mut T, len: usize) -> &'a mut [T] {
1431 mem::transmute(RawSlice { data: p, len: len })
1438 /// Operations on `[u8]`.
1439 #[unstable(feature = "slice_bytes", reason = "needs review",
1441 #[rustc_deprecated(reason = "unidiomatic functions not pulling their weight",
1443 #[allow(deprecated)]
1446 use slice::SliceExt;
1448 /// A trait for operations on mutable `[u8]`s.
1449 pub trait MutableByteVector {
1450 /// Sets all bytes of the receiver to the given value.
1451 fn set_memory(&mut self, value: u8);
1454 impl MutableByteVector for [u8] {
1456 fn set_memory(&mut self, value: u8) {
1457 unsafe { ptr::write_bytes(self.as_mut_ptr(), value, self.len()) };
1461 /// Copies data from `src` to `dst`
1463 /// Panics if the length of `dst` is less than the length of `src`.
1465 pub fn copy_memory(src: &[u8], dst: &mut [u8]) {
1466 let len_src = src.len();
1467 assert!(dst.len() >= len_src);
1468 // `dst` is unaliasable, so we know statically it doesn't overlap
1471 ptr::copy_nonoverlapping(src.as_ptr(),
1481 // Boilerplate traits
1484 #[stable(feature = "rust1", since = "1.0.0")]
1485 impl<A, B> PartialEq<[B]> for [A] where A: PartialEq<B> {
1486 fn eq(&self, other: &[B]) -> bool {
1487 if self.len() != other.len() {
1491 for i in 0..self.len() {
1492 if !self[i].eq(&other[i]) {
1499 fn ne(&self, other: &[B]) -> bool {
1500 if self.len() != other.len() {
1504 for i in 0..self.len() {
1505 if self[i].ne(&other[i]) {
1514 #[stable(feature = "rust1", since = "1.0.0")]
1515 impl<T: Eq> Eq for [T] {}
1517 #[stable(feature = "rust1", since = "1.0.0")]
1518 impl<T: Ord> Ord for [T] {
1519 fn cmp(&self, other: &[T]) -> Ordering {
1520 let l = cmp::min(self.len(), other.len());
1522 // Slice to the loop iteration range to enable bound check
1523 // elimination in the compiler
1524 let lhs = &self[..l];
1525 let rhs = &other[..l];
1528 match lhs[i].cmp(&rhs[i]) {
1529 Ordering::Equal => (),
1530 non_eq => return non_eq,
1534 self.len().cmp(&other.len())
1538 #[stable(feature = "rust1", since = "1.0.0")]
1539 impl<T: PartialOrd> PartialOrd for [T] {
1540 fn partial_cmp(&self, other: &[T]) -> Option<Ordering> {
1541 let l = cmp::min(self.len(), other.len());
1543 // Slice to the loop iteration range to enable bound check
1544 // elimination in the compiler
1545 let lhs = &self[..l];
1546 let rhs = &other[..l];
1549 match lhs[i].partial_cmp(&rhs[i]) {
1550 Some(Ordering::Equal) => (),
1551 non_eq => return non_eq,
1555 self.len().partial_cmp(&other.len())