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// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! Slice management and manipulation
//!
//! For more details `std::slice`.
#![stable(feature = "rust1", since = "1.0.0")]
// How this module is organized.
//
// The library infrastructure for slices is fairly messy. There's
// a lot of stuff defined here. Let's keep it clean.
//
// Since slices don't support inherent methods; all operations
// on them are defined on traits, which are then reexported from
// the prelude for convenience. So there are a lot of traits here.
//
// The layout of this file is thus:
//
// * Slice-specific 'extension' traits and their implementations. This
// is where most of the slice API resides.
// * Implementations of a few common traits with important slice ops.
// * Definitions of a bunch of iterators.
// * Free functions.
// * The `raw` and `bytes` submodules.
// * Boilerplate trait implementations.
use cmp::Ordering::{self, Less, Equal, Greater};
use cmp;
use fmt;
use intrinsics::assume;
use iter::*;
use ops::{self, RangeFull};
use ptr;
use mem;
use marker;
use iter_private::TrustedRandomAccess;
#[repr(C)]
struct Repr<T> {
pub data: *const T,
pub len: usize,
}
//
// Extension traits
//
/// Extension methods for slices.
#[unstable(feature = "core_slice_ext",
reason = "stable interface provided by `impl [T]` in later crates",
issue = "32110")]
#[allow(missing_docs)] // documented elsewhere
pub trait SliceExt {
type Item;
#[stable(feature = "core", since = "1.6.0")]
fn split_at(&self, mid: usize) -> (&[Self::Item], &[Self::Item]);
#[stable(feature = "core", since = "1.6.0")]
fn iter(&self) -> Iter<Self::Item>;
#[stable(feature = "core", since = "1.6.0")]
fn split<P>(&self, pred: P) -> Split<Self::Item, P>
where P: FnMut(&Self::Item) -> bool;
#[stable(feature = "core", since = "1.6.0")]
fn splitn<P>(&self, n: usize, pred: P) -> SplitN<Self::Item, P>
where P: FnMut(&Self::Item) -> bool;
#[stable(feature = "core", since = "1.6.0")]
fn rsplitn<P>(&self, n: usize, pred: P) -> RSplitN<Self::Item, P>
where P: FnMut(&Self::Item) -> bool;
#[stable(feature = "core", since = "1.6.0")]
fn windows(&self, size: usize) -> Windows<Self::Item>;
#[stable(feature = "core", since = "1.6.0")]
fn chunks(&self, size: usize) -> Chunks<Self::Item>;
#[stable(feature = "core", since = "1.6.0")]
fn get(&self, index: usize) -> Option<&Self::Item>;
#[stable(feature = "core", since = "1.6.0")]
fn first(&self) -> Option<&Self::Item>;
#[stable(feature = "core", since = "1.6.0")]
fn split_first(&self) -> Option<(&Self::Item, &[Self::Item])>;
#[stable(feature = "core", since = "1.6.0")]
fn split_last(&self) -> Option<(&Self::Item, &[Self::Item])>;
#[stable(feature = "core", since = "1.6.0")]
fn last(&self) -> Option<&Self::Item>;
#[stable(feature = "core", since = "1.6.0")]
unsafe fn get_unchecked(&self, index: usize) -> &Self::Item;
#[stable(feature = "core", since = "1.6.0")]
fn as_ptr(&self) -> *const Self::Item;
#[stable(feature = "core", since = "1.6.0")]
fn binary_search(&self, x: &Self::Item) -> Result<usize, usize>
where Self::Item: Ord;
#[stable(feature = "core", since = "1.6.0")]
fn binary_search_by<'a, F>(&'a self, f: F) -> Result<usize, usize>
where F: FnMut(&'a Self::Item) -> Ordering;
#[stable(feature = "slice_binary_search_by_key", since = "1.10.0")]
fn binary_search_by_key<'a, B, F>(&'a self, b: &B, f: F) -> Result<usize, usize>
where F: FnMut(&'a Self::Item) -> B,
B: Ord;
#[stable(feature = "core", since = "1.6.0")]
fn len(&self) -> usize;
#[stable(feature = "core", since = "1.6.0")]
fn is_empty(&self) -> bool { self.len() == 0 }
#[stable(feature = "core", since = "1.6.0")]
fn get_mut(&mut self, index: usize) -> Option<&mut Self::Item>;
#[stable(feature = "core", since = "1.6.0")]
fn iter_mut(&mut self) -> IterMut<Self::Item>;
#[stable(feature = "core", since = "1.6.0")]
fn first_mut(&mut self) -> Option<&mut Self::Item>;
#[stable(feature = "core", since = "1.6.0")]
fn split_first_mut(&mut self) -> Option<(&mut Self::Item, &mut [Self::Item])>;
#[stable(feature = "core", since = "1.6.0")]
fn split_last_mut(&mut self) -> Option<(&mut Self::Item, &mut [Self::Item])>;
#[stable(feature = "core", since = "1.6.0")]
fn last_mut(&mut self) -> Option<&mut Self::Item>;
#[stable(feature = "core", since = "1.6.0")]
fn split_mut<P>(&mut self, pred: P) -> SplitMut<Self::Item, P>
where P: FnMut(&Self::Item) -> bool;
#[stable(feature = "core", since = "1.6.0")]
fn splitn_mut<P>(&mut self, n: usize, pred: P) -> SplitNMut<Self::Item, P>
where P: FnMut(&Self::Item) -> bool;
#[stable(feature = "core", since = "1.6.0")]
fn rsplitn_mut<P>(&mut self, n: usize, pred: P) -> RSplitNMut<Self::Item, P>
where P: FnMut(&Self::Item) -> bool;
#[stable(feature = "core", since = "1.6.0")]
fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<Self::Item>;
#[stable(feature = "core", since = "1.6.0")]
fn swap(&mut self, a: usize, b: usize);
#[stable(feature = "core", since = "1.6.0")]
fn split_at_mut(&mut self, mid: usize) -> (&mut [Self::Item], &mut [Self::Item]);
#[stable(feature = "core", since = "1.6.0")]
fn reverse(&mut self);
#[stable(feature = "core", since = "1.6.0")]
unsafe fn get_unchecked_mut(&mut self, index: usize) -> &mut Self::Item;
#[stable(feature = "core", since = "1.6.0")]
fn as_mut_ptr(&mut self) -> *mut Self::Item;
#[stable(feature = "core", since = "1.6.0")]
fn contains(&self, x: &Self::Item) -> bool where Self::Item: PartialEq;
#[stable(feature = "core", since = "1.6.0")]
fn starts_with(&self, needle: &[Self::Item]) -> bool where Self::Item: PartialEq;
#[stable(feature = "core", since = "1.6.0")]
fn ends_with(&self, needle: &[Self::Item]) -> bool where Self::Item: PartialEq;
#[stable(feature = "clone_from_slice", since = "1.7.0")]
fn clone_from_slice(&mut self, src: &[Self::Item]) where Self::Item: Clone;
#[stable(feature = "copy_from_slice", since = "1.9.0")]
fn copy_from_slice(&mut self, src: &[Self::Item]) where Self::Item: Copy;
}
// Use macros to be generic over const/mut
macro_rules! slice_offset {
($ptr:expr, $by:expr) => {{
let ptr = $ptr;
if size_from_ptr(ptr) == 0 {
::intrinsics::arith_offset(ptr as *mut i8, $by) as *mut _
} else {
ptr.offset($by)
}
}};
}
macro_rules! slice_ref {
($ptr:expr) => {{
let ptr = $ptr;
if size_from_ptr(ptr) == 0 {
// Use a non-null pointer value
&mut *(1 as *mut _)
} else {
mem::transmute(ptr)
}
}};
}
#[unstable(feature = "core_slice_ext",
reason = "stable interface provided by `impl [T]` in later crates",
issue = "32110")]
impl<T> SliceExt for [T] {
type Item = T;
#[inline]
fn split_at(&self, mid: usize) -> (&[T], &[T]) {
(&self[..mid], &self[mid..])
}
#[inline]
fn iter(&self) -> Iter<T> {
unsafe {
let p = if mem::size_of::<T>() == 0 {
1 as *const _
} else {
let p = self.as_ptr();
assume(!p.is_null());
p
};
Iter {
ptr: p,
end: slice_offset!(p, self.len() as isize),
_marker: marker::PhantomData
}
}
}
#[inline]
fn split<P>(&self, pred: P) -> Split<T, P> where P: FnMut(&T) -> bool {
Split {
v: self,
pred: pred,
finished: false
}
}
#[inline]
fn splitn<P>(&self, n: usize, pred: P) -> SplitN<T, P> where
P: FnMut(&T) -> bool,
{
SplitN {
inner: GenericSplitN {
iter: self.split(pred),
count: n,
invert: false
}
}
}
#[inline]
fn rsplitn<P>(&self, n: usize, pred: P) -> RSplitN<T, P> where
P: FnMut(&T) -> bool,
{
RSplitN {
inner: GenericSplitN {
iter: self.split(pred),
count: n,
invert: true
}
}
}
#[inline]
fn windows(&self, size: usize) -> Windows<T> {
assert!(size != 0);
Windows { v: self, size: size }
}
#[inline]
fn chunks(&self, size: usize) -> Chunks<T> {
assert!(size != 0);
Chunks { v: self, size: size }
}
#[inline]
fn get(&self, index: usize) -> Option<&T> {
if index < self.len() { Some(&self[index]) } else { None }
}
#[inline]
fn first(&self) -> Option<&T> {
if self.is_empty() { None } else { Some(&self[0]) }
}
#[inline]
fn split_first(&self) -> Option<(&T, &[T])> {
if self.is_empty() { None } else { Some((&self[0], &self[1..])) }
}
#[inline]
fn split_last(&self) -> Option<(&T, &[T])> {
let len = self.len();
if len == 0 { None } else { Some((&self[len - 1], &self[..(len - 1)])) }
}
#[inline]
fn last(&self) -> Option<&T> {
if self.is_empty() { None } else { Some(&self[self.len() - 1]) }
}
#[inline]
unsafe fn get_unchecked(&self, index: usize) -> &T {
&*(self.as_ptr().offset(index as isize))
}
#[inline]
fn as_ptr(&self) -> *const T {
self as *const [T] as *const T
}
fn binary_search_by<'a, F>(&'a self, mut f: F) -> Result<usize, usize>
where F: FnMut(&'a T) -> Ordering
{
let mut base = 0usize;
let mut s = self;
loop {
let (head, tail) = s.split_at(s.len() >> 1);
if tail.is_empty() {
return Err(base)
}
match f(&tail[0]) {
Less => {
base += head.len() + 1;
s = &tail[1..];
}
Greater => s = head,
Equal => return Ok(base + head.len()),
}
}
}
#[inline]
fn len(&self) -> usize {
unsafe {
mem::transmute::<&[T], Repr<T>>(self).len
}
}
#[inline]
fn get_mut(&mut self, index: usize) -> Option<&mut T> {
if index < self.len() { Some(&mut self[index]) } else { None }
}
#[inline]
fn split_at_mut(&mut self, mid: usize) -> (&mut [T], &mut [T]) {
let len = self.len();
let ptr = self.as_mut_ptr();
unsafe {
assert!(mid <= len);
(from_raw_parts_mut(ptr, mid),
from_raw_parts_mut(ptr.offset(mid as isize), len - mid))
}
}
#[inline]
fn iter_mut(&mut self) -> IterMut<T> {
unsafe {
let p = if mem::size_of::<T>() == 0 {
1 as *mut _
} else {
let p = self.as_mut_ptr();
assume(!p.is_null());
p
};
IterMut {
ptr: p,
end: slice_offset!(p, self.len() as isize),
_marker: marker::PhantomData
}
}
}
#[inline]
fn last_mut(&mut self) -> Option<&mut T> {
let len = self.len();
if len == 0 { return None; }
Some(&mut self[len - 1])
}
#[inline]
fn first_mut(&mut self) -> Option<&mut T> {
if self.is_empty() { None } else { Some(&mut self[0]) }
}
#[inline]
fn split_first_mut(&mut self) -> Option<(&mut T, &mut [T])> {
if self.is_empty() { None } else {
let split = self.split_at_mut(1);
Some((&mut split.0[0], split.1))
}
}
#[inline]
fn split_last_mut(&mut self) -> Option<(&mut T, &mut [T])> {
let len = self.len();
if len == 0 { None } else {
let split = self.split_at_mut(len - 1);
Some((&mut split.1[0], split.0))
}
}
#[inline]
fn split_mut<P>(&mut self, pred: P) -> SplitMut<T, P> where P: FnMut(&T) -> bool {
SplitMut { v: self, pred: pred, finished: false }
}
#[inline]
fn splitn_mut<P>(&mut self, n: usize, pred: P) -> SplitNMut<T, P> where
P: FnMut(&T) -> bool
{
SplitNMut {
inner: GenericSplitN {
iter: self.split_mut(pred),
count: n,
invert: false
}
}
}
#[inline]
fn rsplitn_mut<P>(&mut self, n: usize, pred: P) -> RSplitNMut<T, P> where
P: FnMut(&T) -> bool,
{
RSplitNMut {
inner: GenericSplitN {
iter: self.split_mut(pred),
count: n,
invert: true
}
}
}
#[inline]
fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<T> {
assert!(chunk_size > 0);
ChunksMut { v: self, chunk_size: chunk_size }
}
#[inline]
fn swap(&mut self, a: usize, b: usize) {
unsafe {
// Can't take two mutable loans from one vector, so instead just cast
// them to their raw pointers to do the swap
let pa: *mut T = &mut self[a];
let pb: *mut T = &mut self[b];
ptr::swap(pa, pb);
}
}
fn reverse(&mut self) {
let mut i: usize = 0;
let ln = self.len();
while i < ln / 2 {
// Unsafe swap to avoid the bounds check in safe swap.
unsafe {
let pa: *mut T = self.get_unchecked_mut(i);
let pb: *mut T = self.get_unchecked_mut(ln - i - 1);
ptr::swap(pa, pb);
}
i += 1;
}
}
#[inline]
unsafe fn get_unchecked_mut(&mut self, index: usize) -> &mut T {
&mut *self.as_mut_ptr().offset(index as isize)
}
#[inline]
fn as_mut_ptr(&mut self) -> *mut T {
self as *mut [T] as *mut T
}
#[inline]
fn contains(&self, x: &T) -> bool where T: PartialEq {
self.iter().any(|elt| *x == *elt)
}
#[inline]
fn starts_with(&self, needle: &[T]) -> bool where T: PartialEq {
let n = needle.len();
self.len() >= n && needle == &self[..n]
}
#[inline]
fn ends_with(&self, needle: &[T]) -> bool where T: PartialEq {
let (m, n) = (self.len(), needle.len());
m >= n && needle == &self[m-n..]
}
fn binary_search(&self, x: &T) -> Result<usize, usize> where T: Ord {
self.binary_search_by(|p| p.cmp(x))
}
#[inline]
fn clone_from_slice(&mut self, src: &[T]) where T: Clone {
assert!(self.len() == src.len(),
"destination and source slices have different lengths");
// NOTE: We need to explicitly slice them to the same length
// for bounds checking to be elided, and the optimizer will
// generate memcpy for simple cases (for example T = u8).
let len = self.len();
let src = &src[..len];
for i in 0..len {
self[i].clone_from(&src[i]);
}
}
#[inline]
fn copy_from_slice(&mut self, src: &[T]) where T: Copy {
assert!(self.len() == src.len(),
"destination and source slices have different lengths");
unsafe {
ptr::copy_nonoverlapping(
src.as_ptr(), self.as_mut_ptr(), self.len());
}
}
#[inline]
fn binary_search_by_key<'a, B, F>(&'a self, b: &B, mut f: F) -> Result<usize, usize>
where F: FnMut(&'a Self::Item) -> B,
B: Ord
{
self.binary_search_by(|k| f(k).cmp(b))
}
}
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_on_unimplemented = "slice indices are of type `usize`"]
impl<T> ops::Index<usize> for [T] {
type Output = T;
fn index(&self, index: usize) -> &T {
// NB built-in indexing
&(*self)[index]
}
}
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_on_unimplemented = "slice indices are of type `usize`"]
impl<T> ops::IndexMut<usize> for [T] {
#[inline]
fn index_mut(&mut self, index: usize) -> &mut T {
// NB built-in indexing
&mut (*self)[index]
}
}
#[inline(never)]
#[cold]
fn slice_index_len_fail(index: usize, len: usize) -> ! {
panic!("index {} out of range for slice of length {}", index, len);
}
#[inline(never)]
#[cold]
fn slice_index_order_fail(index: usize, end: usize) -> ! {
panic!("slice index starts at {} but ends at {}", index, end);
}
/// Implements slicing with syntax `&self[begin .. end]`.
///
/// Returns a slice of self for the index range [`begin`..`end`).
///
/// This operation is `O(1)`.
///
/// # Panics
///
/// Requires that `begin <= end` and `end <= self.len()`,
/// otherwise slicing will panic.
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_on_unimplemented = "slice indices are of type `usize`"]
impl<T> ops::Index<ops::Range<usize>> for [T] {
type Output = [T];
#[inline]
fn index(&self, index: ops::Range<usize>) -> &[T] {
if index.start > index.end {
slice_index_order_fail(index.start, index.end);
} else if index.end > self.len() {
slice_index_len_fail(index.end, self.len());
}
unsafe {
from_raw_parts (
self.as_ptr().offset(index.start as isize),
index.end - index.start
)
}
}
}
/// Implements slicing with syntax `&self[.. end]`.
///
/// Returns a slice of self from the beginning until but not including
/// the index `end`.
///
/// Equivalent to `&self[0 .. end]`
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_on_unimplemented = "slice indices are of type `usize`"]
impl<T> ops::Index<ops::RangeTo<usize>> for [T] {
type Output = [T];
#[inline]
fn index(&self, index: ops::RangeTo<usize>) -> &[T] {
self.index(0 .. index.end)
}
}
/// Implements slicing with syntax `&self[begin ..]`.
///
/// Returns a slice of self from and including the index `begin` until the end.
///
/// Equivalent to `&self[begin .. self.len()]`
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_on_unimplemented = "slice indices are of type `usize`"]
impl<T> ops::Index<ops::RangeFrom<usize>> for [T] {
type Output = [T];
#[inline]
fn index(&self, index: ops::RangeFrom<usize>) -> &[T] {
self.index(index.start .. self.len())
}
}
/// Implements slicing with syntax `&self[..]`.
///
/// Returns a slice of the whole slice. This operation cannot panic.
///
/// Equivalent to `&self[0 .. self.len()]`
#[stable(feature = "rust1", since = "1.0.0")]
impl<T> ops::Index<RangeFull> for [T] {
type Output = [T];
#[inline]
fn index(&self, _index: RangeFull) -> &[T] {
self
}
}
#[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
#[rustc_on_unimplemented = "slice indices are of type `usize`"]
impl<T> ops::Index<ops::RangeInclusive<usize>> for [T] {
type Output = [T];
#[inline]
fn index(&self, index: ops::RangeInclusive<usize>) -> &[T] {
match index {
ops::RangeInclusive::Empty { .. } => &[],
ops::RangeInclusive::NonEmpty { end, .. } if end == usize::max_value() =>
panic!("attempted to index slice up to maximum usize"),
ops::RangeInclusive::NonEmpty { start, end } =>
self.index(start .. end+1)
}
}
}
#[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
#[rustc_on_unimplemented = "slice indices are of type `usize`"]
impl<T> ops::Index<ops::RangeToInclusive<usize>> for [T] {
type Output = [T];
#[inline]
fn index(&self, index: ops::RangeToInclusive<usize>) -> &[T] {
self.index(0...index.end)
}
}
/// Implements mutable slicing with syntax `&mut self[begin .. end]`.
///
/// Returns a slice of self for the index range [`begin`..`end`).
///
/// This operation is `O(1)`.
///
/// # Panics
///
/// Requires that `begin <= end` and `end <= self.len()`,
/// otherwise slicing will panic.
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_on_unimplemented = "slice indices are of type `usize`"]
impl<T> ops::IndexMut<ops::Range<usize>> for [T] {
#[inline]
fn index_mut(&mut self, index: ops::Range<usize>) -> &mut [T] {
if index.start > index.end {
slice_index_order_fail(index.start, index.end);
} else if index.end > self.len() {
slice_index_len_fail(index.end, self.len());
}
unsafe {
from_raw_parts_mut(
self.as_mut_ptr().offset(index.start as isize),
index.end - index.start
)
}
}
}
/// Implements mutable slicing with syntax `&mut self[.. end]`.
///
/// Returns a slice of self from the beginning until but not including
/// the index `end`.
///
/// Equivalent to `&mut self[0 .. end]`
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_on_unimplemented = "slice indices are of type `usize`"]
impl<T> ops::IndexMut<ops::RangeTo<usize>> for [T] {
#[inline]
fn index_mut(&mut self, index: ops::RangeTo<usize>) -> &mut [T] {
self.index_mut(0 .. index.end)
}
}
/// Implements mutable slicing with syntax `&mut self[begin ..]`.
///
/// Returns a slice of self from and including the index `begin` until the end.
///
/// Equivalent to `&mut self[begin .. self.len()]`
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_on_unimplemented = "slice indices are of type `usize`"]
impl<T> ops::IndexMut<ops::RangeFrom<usize>> for [T] {
#[inline]
fn index_mut(&mut self, index: ops::RangeFrom<usize>) -> &mut [T] {
let len = self.len();
self.index_mut(index.start .. len)
}
}
/// Implements mutable slicing with syntax `&mut self[..]`.
///
/// Returns a slice of the whole slice. This operation can not panic.
///
/// Equivalent to `&mut self[0 .. self.len()]`
#[stable(feature = "rust1", since = "1.0.0")]
impl<T> ops::IndexMut<RangeFull> for [T] {
#[inline]
fn index_mut(&mut self, _index: RangeFull) -> &mut [T] {
self
}
}
#[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
#[rustc_on_unimplemented = "slice indices are of type `usize`"]
impl<T> ops::IndexMut<ops::RangeInclusive<usize>> for [T] {
#[inline]
fn index_mut(&mut self, index: ops::RangeInclusive<usize>) -> &mut [T] {
match index {
ops::RangeInclusive::Empty { .. } => &mut [],
ops::RangeInclusive::NonEmpty { end, .. } if end == usize::max_value() =>
panic!("attempted to index slice up to maximum usize"),
ops::RangeInclusive::NonEmpty { start, end } =>
self.index_mut(start .. end+1)
}
}
}
#[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
#[rustc_on_unimplemented = "slice indices are of type `usize`"]
impl<T> ops::IndexMut<ops::RangeToInclusive<usize>> for [T] {
#[inline]
fn index_mut(&mut self, index: ops::RangeToInclusive<usize>) -> &mut [T] {
self.index_mut(0...index.end)
}
}
////////////////////////////////////////////////////////////////////////////////
// Common traits
////////////////////////////////////////////////////////////////////////////////
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> Default for &'a [T] {
/// Creates an empty slice.
fn default() -> &'a [T] { &[] }
}
#[stable(feature = "mut_slice_default", since = "1.5.0")]
impl<'a, T> Default for &'a mut [T] {
/// Creates a mutable empty slice.
fn default() -> &'a mut [T] { &mut [] }
}
//
// Iterators
//
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> IntoIterator for &'a [T] {
type Item = &'a T;
type IntoIter = Iter<'a, T>;
fn into_iter(self) -> Iter<'a, T> {
self.iter()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> IntoIterator for &'a mut [T] {
type Item = &'a mut T;
type IntoIter = IterMut<'a, T>;
fn into_iter(self) -> IterMut<'a, T> {
self.iter_mut()
}
}
#[inline(always)]
fn size_from_ptr<T>(_: *const T) -> usize {
mem::size_of::<T>()
}
// The shared definition of the `Iter` and `IterMut` iterators
macro_rules! iterator {
(struct $name:ident -> $ptr:ty, $elem:ty) => {
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> Iterator for $name<'a, T> {
type Item = $elem;
#[inline]
fn next(&mut self) -> Option<$elem> {
// could be implemented with slices, but this avoids bounds checks
unsafe {
if mem::size_of::<T>() != 0 {
assume(!self.ptr.is_null());
assume(!self.end.is_null());
}
if self.ptr == self.end {
None
} else {
let old = self.ptr;
self.ptr = slice_offset!(self.ptr, 1);
Some(slice_ref!(old))
}
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
let diff = (self.end as usize).wrapping_sub(self.ptr as usize);
let size = mem::size_of::<T>();
let exact = diff / (if size == 0 {1} else {size});
(exact, Some(exact))
}
#[inline]
fn count(self) -> usize {
self.len()
}
#[inline]
fn nth(&mut self, n: usize) -> Option<$elem> {
// Call helper method. Can't put the definition here because mut versus const.
self.iter_nth(n)
}
#[inline]
fn last(mut self) -> Option<$elem> {
self.next_back()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> DoubleEndedIterator for $name<'a, T> {
#[inline]
fn next_back(&mut self) -> Option<$elem> {
// could be implemented with slices, but this avoids bounds checks
unsafe {
if mem::size_of::<T>() != 0 {
assume(!self.ptr.is_null());
assume(!self.end.is_null());
}
if self.end == self.ptr {
None
} else {
self.end = slice_offset!(self.end, -1);
Some(slice_ref!(self.end))
}
}
}
}
}
}
macro_rules! make_slice {
($start: expr, $end: expr) => {{
let start = $start;
let diff = ($end as usize).wrapping_sub(start as usize);
if size_from_ptr(start) == 0 {
// use a non-null pointer value
unsafe { from_raw_parts(1 as *const _, diff) }
} else {
let len = diff / size_from_ptr(start);
unsafe { from_raw_parts(start, len) }
}
}}
}
macro_rules! make_mut_slice {
($start: expr, $end: expr) => {{
let start = $start;
let diff = ($end as usize).wrapping_sub(start as usize);
if size_from_ptr(start) == 0 {
// use a non-null pointer value
unsafe { from_raw_parts_mut(1 as *mut _, diff) }
} else {
let len = diff / size_from_ptr(start);
unsafe { from_raw_parts_mut(start, len) }
}
}}
}
/// Immutable slice iterator
///
/// This struct is created by the [`iter`] method on [slices].
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// // First, we declare a type which has `iter` method to get the `Iter` struct (&[usize here]):
/// let slice = &[1, 2, 3];
///
/// // Then, we iterate over it:
/// for element in slice.iter() {
/// println!("{}", element);
/// }
/// ```
///
/// [`iter`]: ../../std/primitive.slice.html#method.iter
/// [slices]: ../../std/primitive.slice.html
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Iter<'a, T: 'a> {
ptr: *const T,
end: *const T,
_marker: marker::PhantomData<&'a T>,
}
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<'a, T: 'a + fmt::Debug> fmt::Debug for Iter<'a, T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_tuple("Iter")
.field(&self.as_slice())
.finish()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
unsafe impl<'a, T: Sync> Sync for Iter<'a, T> {}
#[stable(feature = "rust1", since = "1.0.0")]
unsafe impl<'a, T: Sync> Send for Iter<'a, T> {}
impl<'a, T> Iter<'a, T> {
/// View the underlying data as a subslice of the original data.
///
/// This has the same lifetime as the original slice, and so the
/// iterator can continue to be used while this exists.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// // First, we declare a type which has the `iter` method to get the `Iter`
/// // struct (&[usize here]):
/// let slice = &[1, 2, 3];
///
/// // Then, we get the iterator:
/// let mut iter = slice.iter();
/// // So if we print what `as_slice` method returns here, we have "[1, 2, 3]":
/// println!("{:?}", iter.as_slice());
///
/// // Next, we move to the second element of the slice:
/// iter.next();
/// // Now `as_slice` returns "[2, 3]":
/// println!("{:?}", iter.as_slice());
/// ```
#[stable(feature = "iter_to_slice", since = "1.4.0")]
pub fn as_slice(&self) -> &'a [T] {
make_slice!(self.ptr, self.end)
}
// Helper function for Iter::nth
fn iter_nth(&mut self, n: usize) -> Option<&'a T> {
match self.as_slice().get(n) {
Some(elem_ref) => unsafe {
self.ptr = slice_offset!(self.ptr, (n as isize).wrapping_add(1));
Some(elem_ref)
},
None => {
self.ptr = self.end;
None
}
}
}
}
iterator!{struct Iter -> *const T, &'a T}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> ExactSizeIterator for Iter<'a, T> {}
#[unstable(feature = "fused", issue = "35602")]
impl<'a, T> FusedIterator for Iter<'a, T> {}
#[unstable(feature = "trusted_len", issue = "37572")]
unsafe impl<'a, T> TrustedLen for Iter<'a, T> {}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> Clone for Iter<'a, T> {
fn clone(&self) -> Iter<'a, T> { Iter { ptr: self.ptr, end: self.end, _marker: self._marker } }
}
#[stable(feature = "slice_iter_as_ref", since = "1.12.0")]
impl<'a, T> AsRef<[T]> for Iter<'a, T> {
fn as_ref(&self) -> &[T] {
self.as_slice()
}
}
/// Mutable slice iterator.
///
/// This struct is created by the [`iter_mut`] method on [slices].
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// // First, we declare a type which has `iter_mut` method to get the `IterMut`
/// // struct (&[usize here]):
/// let mut slice = &mut [1, 2, 3];
///
/// // Then, we iterate over it and increment each element value:
/// for element in slice.iter_mut() {
/// *element += 1;
/// }
///
/// // We now have "[2, 3, 4]":
/// println!("{:?}", slice);
/// ```
///
/// [`iter_mut`]: ../../std/primitive.slice.html#method.iter_mut
/// [slices]: ../../std/primitive.slice.html
#[stable(feature = "rust1", since = "1.0.0")]
pub struct IterMut<'a, T: 'a> {
ptr: *mut T,
end: *mut T,
_marker: marker::PhantomData<&'a mut T>,
}
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<'a, T: 'a + fmt::Debug> fmt::Debug for IterMut<'a, T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_tuple("IterMut")
.field(&make_slice!(self.ptr, self.end))
.finish()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
unsafe impl<'a, T: Sync> Sync for IterMut<'a, T> {}
#[stable(feature = "rust1", since = "1.0.0")]
unsafe impl<'a, T: Send> Send for IterMut<'a, T> {}
impl<'a, T> IterMut<'a, T> {
/// View the underlying data as a subslice of the original data.
///
/// To avoid creating `&mut` references that alias, this is forced
/// to consume the iterator. Consider using the `Slice` and
/// `SliceMut` implementations for obtaining slices with more
/// restricted lifetimes that do not consume the iterator.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// // First, we declare a type which has `iter_mut` method to get the `IterMut`
/// // struct (&[usize here]):
/// let mut slice = &mut [1, 2, 3];
///
/// {
/// // Then, we get the iterator:
/// let mut iter = slice.iter_mut();
/// // We move to next element:
/// iter.next();
/// // So if we print what `into_slice` method returns here, we have "[2, 3]":
/// println!("{:?}", iter.into_slice());
/// }
///
/// // Now let's modify a value of the slice:
/// {
/// // First we get back the iterator:
/// let mut iter = slice.iter_mut();
/// // We change the value of the first element of the slice returned by the `next` method:
/// *iter.next().unwrap() += 1;
/// }
/// // Now slice is "[2, 2, 3]":
/// println!("{:?}", slice);
/// ```
#[stable(feature = "iter_to_slice", since = "1.4.0")]
pub fn into_slice(self) -> &'a mut [T] {
make_mut_slice!(self.ptr, self.end)
}
// Helper function for IterMut::nth
fn iter_nth(&mut self, n: usize) -> Option<&'a mut T> {
match make_mut_slice!(self.ptr, self.end).get_mut(n) {
Some(elem_ref) => unsafe {
self.ptr = slice_offset!(self.ptr, (n as isize).wrapping_add(1));
Some(elem_ref)
},
None => {
self.ptr = self.end;
None
}
}
}
}
iterator!{struct IterMut -> *mut T, &'a mut T}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> ExactSizeIterator for IterMut<'a, T> {}
#[unstable(feature = "fused", issue = "35602")]
impl<'a, T> FusedIterator for IterMut<'a, T> {}
#[unstable(feature = "trusted_len", issue = "37572")]
unsafe impl<'a, T> TrustedLen for IterMut<'a, T> {}
/// An internal abstraction over the splitting iterators, so that
/// splitn, splitn_mut etc can be implemented once.
#[doc(hidden)]
trait SplitIter: DoubleEndedIterator {
/// Mark the underlying iterator as complete, extracting the remaining
/// portion of the slice.
fn finish(&mut self) -> Option<Self::Item>;
}
/// An iterator over subslices separated by elements that match a predicate
/// function.
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Split<'a, T:'a, P> where P: FnMut(&T) -> bool {
v: &'a [T],
pred: P,
finished: bool
}
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for Split<'a, T, P> where P: FnMut(&T) -> bool {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("Split")
.field("v", &self.v)
.field("finished", &self.finished)
.finish()
}
}
// FIXME(#19839) Remove in favor of `#[derive(Clone)]`
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T, P> Clone for Split<'a, T, P> where P: Clone + FnMut(&T) -> bool {
fn clone(&self) -> Split<'a, T, P> {
Split {
v: self.v,
pred: self.pred.clone(),
finished: self.finished,
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T, P> Iterator for Split<'a, T, P> where P: FnMut(&T) -> bool {
type Item = &'a [T];
#[inline]
fn next(&mut self) -> Option<&'a [T]> {
if self.finished { return None; }
match self.v.iter().position(|x| (self.pred)(x)) {
None => self.finish(),
Some(idx) => {
let ret = Some(&self.v[..idx]);
self.v = &self.v[idx + 1..];
ret
}
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
if self.finished {
(0, Some(0))
} else {
(1, Some(self.v.len() + 1))
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T, P> DoubleEndedIterator for Split<'a, T, P> where P: FnMut(&T) -> bool {
#[inline]
fn next_back(&mut self) -> Option<&'a [T]> {
if self.finished { return None; }
match self.v.iter().rposition(|x| (self.pred)(x)) {
None => self.finish(),
Some(idx) => {
let ret = Some(&self.v[idx + 1..]);
self.v = &self.v[..idx];
ret
}
}
}
}
impl<'a, T, P> SplitIter for Split<'a, T, P> where P: FnMut(&T) -> bool {
#[inline]
fn finish(&mut self) -> Option<&'a [T]> {
if self.finished { None } else { self.finished = true; Some(self.v) }
}
}
#[unstable(feature = "fused", issue = "35602")]
impl<'a, T, P> FusedIterator for Split<'a, T, P> where P: FnMut(&T) -> bool {}
/// An iterator over the subslices of the vector which are separated
/// by elements that match `pred`.
#[stable(feature = "rust1", since = "1.0.0")]
pub struct SplitMut<'a, T:'a, P> where P: FnMut(&T) -> bool {
v: &'a mut [T],
pred: P,
finished: bool
}
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("SplitMut")
.field("v", &self.v)
.field("finished", &self.finished)
.finish()
}
}
impl<'a, T, P> SplitIter for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {
#[inline]
fn finish(&mut self) -> Option<&'a mut [T]> {
if self.finished {
None
} else {
self.finished = true;
Some(mem::replace(&mut self.v, &mut []))
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T, P> Iterator for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {
type Item = &'a mut [T];
#[inline]
fn next(&mut self) -> Option<&'a mut [T]> {
if self.finished { return None; }
let idx_opt = { // work around borrowck limitations
let pred = &mut self.pred;
self.v.iter().position(|x| (*pred)(x))
};
match idx_opt {
None => self.finish(),
Some(idx) => {
let tmp = mem::replace(&mut self.v, &mut []);
let (head, tail) = tmp.split_at_mut(idx);
self.v = &mut tail[1..];
Some(head)
}
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
if self.finished {
(0, Some(0))
} else {
// if the predicate doesn't match anything, we yield one slice
// if it matches every element, we yield len+1 empty slices.
(1, Some(self.v.len() + 1))
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T, P> DoubleEndedIterator for SplitMut<'a, T, P> where
P: FnMut(&T) -> bool,
{
#[inline]
fn next_back(&mut self) -> Option<&'a mut [T]> {
if self.finished { return None; }
let idx_opt = { // work around borrowck limitations
let pred = &mut self.pred;
self.v.iter().rposition(|x| (*pred)(x))
};
match idx_opt {
None => self.finish(),
Some(idx) => {
let tmp = mem::replace(&mut self.v, &mut []);
let (head, tail) = tmp.split_at_mut(idx);
self.v = head;
Some(&mut tail[1..])
}
}
}
}
#[unstable(feature = "fused", issue = "35602")]
impl<'a, T, P> FusedIterator for SplitMut<'a, T, P> where P: FnMut(&T) -> bool {}
/// An private iterator over subslices separated by elements that
/// match a predicate function, splitting at most a fixed number of
/// times.
#[derive(Debug)]
struct GenericSplitN<I> {
iter: I,
count: usize,
invert: bool
}
impl<T, I: SplitIter<Item=T>> Iterator for GenericSplitN<I> {
type Item = T;
#[inline]
fn next(&mut self) -> Option<T> {
match self.count {
0 => None,
1 => { self.count -= 1; self.iter.finish() }
_ => {
self.count -= 1;
if self.invert {self.iter.next_back()} else {self.iter.next()}
}
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
let (lower, upper_opt) = self.iter.size_hint();
(lower, upper_opt.map(|upper| cmp::min(self.count, upper)))
}
}
/// An iterator over subslices separated by elements that match a predicate
/// function, limited to a given number of splits.
#[stable(feature = "rust1", since = "1.0.0")]
pub struct SplitN<'a, T: 'a, P> where P: FnMut(&T) -> bool {
inner: GenericSplitN<Split<'a, T, P>>
}
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for SplitN<'a, T, P> where P: FnMut(&T) -> bool {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("SplitN")
.field("inner", &self.inner)
.finish()
}
}
/// An iterator over subslices separated by elements that match a
/// predicate function, limited to a given number of splits, starting
/// from the end of the slice.
#[stable(feature = "rust1", since = "1.0.0")]
pub struct RSplitN<'a, T: 'a, P> where P: FnMut(&T) -> bool {
inner: GenericSplitN<Split<'a, T, P>>
}
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for RSplitN<'a, T, P> where P: FnMut(&T) -> bool {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("RSplitN")
.field("inner", &self.inner)
.finish()
}
}
/// An iterator over subslices separated by elements that match a predicate
/// function, limited to a given number of splits.
#[stable(feature = "rust1", since = "1.0.0")]
pub struct SplitNMut<'a, T: 'a, P> where P: FnMut(&T) -> bool {
inner: GenericSplitN<SplitMut<'a, T, P>>
}
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for SplitNMut<'a, T, P> where P: FnMut(&T) -> bool {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("SplitNMut")
.field("inner", &self.inner)
.finish()
}
}
/// An iterator over subslices separated by elements that match a
/// predicate function, limited to a given number of splits, starting
/// from the end of the slice.
#[stable(feature = "rust1", since = "1.0.0")]
pub struct RSplitNMut<'a, T: 'a, P> where P: FnMut(&T) -> bool {
inner: GenericSplitN<SplitMut<'a, T, P>>
}
#[stable(feature = "core_impl_debug", since = "1.9.0")]
impl<'a, T: 'a + fmt::Debug, P> fmt::Debug for RSplitNMut<'a, T, P> where P: FnMut(&T) -> bool {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("RSplitNMut")
.field("inner", &self.inner)
.finish()
}
}
macro_rules! forward_iterator {
($name:ident: $elem:ident, $iter_of:ty) => {
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, $elem, P> Iterator for $name<'a, $elem, P> where
P: FnMut(&T) -> bool
{
type Item = $iter_of;
#[inline]
fn next(&mut self) -> Option<$iter_of> {
self.inner.next()
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
}
#[unstable(feature = "fused", issue = "35602")]
impl<'a, $elem, P> FusedIterator for $name<'a, $elem, P>
where P: FnMut(&T) -> bool {}
}
}
forward_iterator! { SplitN: T, &'a [T] }
forward_iterator! { RSplitN: T, &'a [T] }
forward_iterator! { SplitNMut: T, &'a mut [T] }
forward_iterator! { RSplitNMut: T, &'a mut [T] }
/// An iterator over overlapping subslices of length `size`.
#[derive(Debug)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Windows<'a, T:'a> {
v: &'a [T],
size: usize
}
// FIXME(#19839) Remove in favor of `#[derive(Clone)]`
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> Clone for Windows<'a, T> {
fn clone(&self) -> Windows<'a, T> {
Windows {
v: self.v,
size: self.size,
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> Iterator for Windows<'a, T> {
type Item = &'a [T];
#[inline]
fn next(&mut self) -> Option<&'a [T]> {
if self.size > self.v.len() {
None
} else {
let ret = Some(&self.v[..self.size]);
self.v = &self.v[1..];
ret
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
if self.size > self.v.len() {
(0, Some(0))
} else {
let size = self.v.len() - self.size + 1;
(size, Some(size))
}
}
#[inline]
fn count(self) -> usize {
self.len()
}
#[inline]
fn nth(&mut self, n: usize) -> Option<Self::Item> {
let (end, overflow) = self.size.overflowing_add(n);
if end > self.v.len() || overflow {
self.v = &[];
None
} else {
let nth = &self.v[n..end];
self.v = &self.v[n+1..];
Some(nth)
}
}
#[inline]
fn last(self) -> Option<Self::Item> {
if self.size > self.v.len() {
None
} else {
let start = self.v.len() - self.size;
Some(&self.v[start..])
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> DoubleEndedIterator for Windows<'a, T> {
#[inline]
fn next_back(&mut self) -> Option<&'a [T]> {
if self.size > self.v.len() {
None
} else {
let ret = Some(&self.v[self.v.len()-self.size..]);
self.v = &self.v[..self.v.len()-1];
ret
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> ExactSizeIterator for Windows<'a, T> {}
#[unstable(feature = "fused", issue = "35602")]
impl<'a, T> FusedIterator for Windows<'a, T> {}
/// An iterator over a slice in (non-overlapping) chunks (`size` elements at a
/// time).
///
/// When the slice len is not evenly divided by the chunk size, the last slice
/// of the iteration will be the remainder.
#[derive(Debug)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Chunks<'a, T:'a> {
v: &'a [T],
size: usize
}
// FIXME(#19839) Remove in favor of `#[derive(Clone)]`
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> Clone for Chunks<'a, T> {
fn clone(&self) -> Chunks<'a, T> {
Chunks {
v: self.v,
size: self.size,
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> Iterator for Chunks<'a, T> {
type Item = &'a [T];
#[inline]
fn next(&mut self) -> Option<&'a [T]> {
if self.v.is_empty() {
None
} else {
let chunksz = cmp::min(self.v.len(), self.size);
let (fst, snd) = self.v.split_at(chunksz);
self.v = snd;
Some(fst)
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
if self.v.is_empty() {
(0, Some(0))
} else {
let n = self.v.len() / self.size;
let rem = self.v.len() % self.size;
let n = if rem > 0 { n+1 } else { n };
(n, Some(n))
}
}
#[inline]
fn count(self) -> usize {
self.len()
}
#[inline]
fn nth(&mut self, n: usize) -> Option<Self::Item> {
let (start, overflow) = n.overflowing_mul(self.size);
if start >= self.v.len() || overflow {
self.v = &[];
None
} else {
let end = match start.checked_add(self.size) {
Some(sum) => cmp::min(self.v.len(), sum),
None => self.v.len(),
};
let nth = &self.v[start..end];
self.v = &self.v[end..];
Some(nth)
}
}
#[inline]
fn last(self) -> Option<Self::Item> {
if self.v.is_empty() {
None
} else {
let start = (self.v.len() - 1) / self.size * self.size;
Some(&self.v[start..])
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> DoubleEndedIterator for Chunks<'a, T> {
#[inline]
fn next_back(&mut self) -> Option<&'a [T]> {
if self.v.is_empty() {
None
} else {
let remainder = self.v.len() % self.size;
let chunksz = if remainder != 0 { remainder } else { self.size };
let (fst, snd) = self.v.split_at(self.v.len() - chunksz);
self.v = fst;
Some(snd)
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> ExactSizeIterator for Chunks<'a, T> {}
#[unstable(feature = "fused", issue = "35602")]
impl<'a, T> FusedIterator for Chunks<'a, T> {}
/// An iterator over a slice in (non-overlapping) mutable chunks (`size`
/// elements at a time). When the slice len is not evenly divided by the chunk
/// size, the last slice of the iteration will be the remainder.
#[derive(Debug)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct ChunksMut<'a, T:'a> {
v: &'a mut [T],
chunk_size: usize
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> Iterator for ChunksMut<'a, T> {
type Item = &'a mut [T];
#[inline]
fn next(&mut self) -> Option<&'a mut [T]> {
if self.v.is_empty() {
None
} else {
let sz = cmp::min(self.v.len(), self.chunk_size);
let tmp = mem::replace(&mut self.v, &mut []);
let (head, tail) = tmp.split_at_mut(sz);
self.v = tail;
Some(head)
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
if self.v.is_empty() {
(0, Some(0))
} else {
let n = self.v.len() / self.chunk_size;
let rem = self.v.len() % self.chunk_size;
let n = if rem > 0 { n + 1 } else { n };
(n, Some(n))
}
}
#[inline]
fn count(self) -> usize {
self.len()
}
#[inline]
fn nth(&mut self, n: usize) -> Option<&'a mut [T]> {
let (start, overflow) = n.overflowing_mul(self.chunk_size);
if start >= self.v.len() || overflow {
self.v = &mut [];
None
} else {
let end = match start.checked_add(self.chunk_size) {
Some(sum) => cmp::min(self.v.len(), sum),
None => self.v.len(),
};
let tmp = mem::replace(&mut self.v, &mut []);
let (head, tail) = tmp.split_at_mut(end);
let (_, nth) = head.split_at_mut(start);
self.v = tail;
Some(nth)
}
}
#[inline]
fn last(self) -> Option<Self::Item> {
if self.v.is_empty() {
None
} else {
let start = (self.v.len() - 1) / self.chunk_size * self.chunk_size;
Some(&mut self.v[start..])
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> DoubleEndedIterator for ChunksMut<'a, T> {
#[inline]
fn next_back(&mut self) -> Option<&'a mut [T]> {
if self.v.is_empty() {
None
} else {
let remainder = self.v.len() % self.chunk_size;
let sz = if remainder != 0 { remainder } else { self.chunk_size };
let tmp = mem::replace(&mut self.v, &mut []);
let tmp_len = tmp.len();
let (head, tail) = tmp.split_at_mut(tmp_len - sz);
self.v = head;
Some(tail)
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, T> ExactSizeIterator for ChunksMut<'a, T> {}
#[unstable(feature = "fused", issue = "35602")]
impl<'a, T> FusedIterator for ChunksMut<'a, T> {}
//
// Free functions
//
/// Forms a slice from a pointer and a length.
///
/// The `len` argument is the number of **elements**, not the number of bytes.
///
/// # Safety
///
/// This function is unsafe as there is no guarantee that the given pointer is
/// valid for `len` elements, nor whether the lifetime inferred is a suitable
/// lifetime for the returned slice.
///
/// `p` must be non-null, even for zero-length slices.
///
/// # Caveat
///
/// The lifetime for the returned slice is inferred from its usage. To
/// prevent accidental misuse, it's suggested to tie the lifetime to whichever
/// source lifetime is safe in the context, such as by providing a helper
/// function taking the lifetime of a host value for the slice, or by explicit
/// annotation.
///
/// # Examples
///
/// ```
/// use std::slice;
///
/// // manifest a slice out of thin air!
/// let ptr = 0x1234 as *const usize;
/// let amt = 10;
/// unsafe {
/// let slice = slice::from_raw_parts(ptr, amt);
/// }
/// ```
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub unsafe fn from_raw_parts<'a, T>(p: *const T, len: usize) -> &'a [T] {
mem::transmute(Repr { data: p, len: len })
}
/// Performs the same functionality as `from_raw_parts`, except that a mutable
/// slice is returned.
///
/// This function is unsafe for the same reasons as `from_raw_parts`, as well
/// as not being able to provide a non-aliasing guarantee of the returned
/// mutable slice.
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub unsafe fn from_raw_parts_mut<'a, T>(p: *mut T, len: usize) -> &'a mut [T] {
mem::transmute(Repr { data: p, len: len })
}
//
// Comparison traits
//
extern {
/// Call implementation provided memcmp
///
/// Interprets the data as u8.
///
/// Return 0 for equal, < 0 for less than and > 0 for greater
/// than.
// FIXME(#32610): Return type should be c_int
fn memcmp(s1: *const u8, s2: *const u8, n: usize) -> i32;
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<A, B> PartialEq<[B]> for [A] where A: PartialEq<B> {
fn eq(&self, other: &[B]) -> bool {
SlicePartialEq::equal(self, other)
}
fn ne(&self, other: &[B]) -> bool {
SlicePartialEq::not_equal(self, other)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<T: Eq> Eq for [T] {}
#[stable(feature = "rust1", since = "1.0.0")]
impl<T: Ord> Ord for [T] {
fn cmp(&self, other: &[T]) -> Ordering {
SliceOrd::compare(self, other)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<T: PartialOrd> PartialOrd for [T] {
fn partial_cmp(&self, other: &[T]) -> Option<Ordering> {
SlicePartialOrd::partial_compare(self, other)
}
}
#[doc(hidden)]
// intermediate trait for specialization of slice's PartialEq
trait SlicePartialEq<B> {
fn equal(&self, other: &[B]) -> bool;
fn not_equal(&self, other: &[B]) -> bool { !self.equal(other) }
}
// Generic slice equality
impl<A, B> SlicePartialEq<B> for [A]
where A: PartialEq<B>
{
default fn equal(&self, other: &[B]) -> bool {
if self.len() != other.len() {
return false;
}
for i in 0..self.len() {
if !self[i].eq(&other[i]) {
return false;
}
}
true
}
}
// Use memcmp for bytewise equality when the types allow
impl<A> SlicePartialEq<A> for [A]
where A: PartialEq<A> + BytewiseEquality
{
fn equal(&self, other: &[A]) -> bool {
if self.len() != other.len() {
return false;
}
if self.as_ptr() == other.as_ptr() {
return true;
}
unsafe {
let size = mem::size_of_val(self);
memcmp(self.as_ptr() as *const u8,
other.as_ptr() as *const u8, size) == 0
}
}
}
#[doc(hidden)]
// intermediate trait for specialization of slice's PartialOrd
trait SlicePartialOrd<B> {
fn partial_compare(&self, other: &[B]) -> Option<Ordering>;
}
impl<A> SlicePartialOrd<A> for [A]
where A: PartialOrd
{
default fn partial_compare(&self, other: &[A]) -> Option<Ordering> {
let l = cmp::min(self.len(), other.len());
// Slice to the loop iteration range to enable bound check
// elimination in the compiler
let lhs = &self[..l];
let rhs = &other[..l];
for i in 0..l {
match lhs[i].partial_cmp(&rhs[i]) {
Some(Ordering::Equal) => (),
non_eq => return non_eq,
}
}
self.len().partial_cmp(&other.len())
}
}
impl SlicePartialOrd<u8> for [u8] {
#[inline]
fn partial_compare(&self, other: &[u8]) -> Option<Ordering> {
Some(SliceOrd::compare(self, other))
}
}
#[doc(hidden)]
// intermediate trait for specialization of slice's Ord
trait SliceOrd<B> {
fn compare(&self, other: &[B]) -> Ordering;
}
impl<A> SliceOrd<A> for [A]
where A: Ord
{
default fn compare(&self, other: &[A]) -> Ordering {
let l = cmp::min(self.len(), other.len());
// Slice to the loop iteration range to enable bound check
// elimination in the compiler
let lhs = &self[..l];
let rhs = &other[..l];
for i in 0..l {
match lhs[i].cmp(&rhs[i]) {
Ordering::Equal => (),
non_eq => return non_eq,
}
}
self.len().cmp(&other.len())
}
}
// memcmp compares a sequence of unsigned bytes lexicographically.
// this matches the order we want for [u8], but no others (not even [i8]).
impl SliceOrd<u8> for [u8] {
#[inline]
fn compare(&self, other: &[u8]) -> Ordering {
let order = unsafe {
memcmp(self.as_ptr(), other.as_ptr(),
cmp::min(self.len(), other.len()))
};
if order == 0 {
self.len().cmp(&other.len())
} else if order < 0 {
Less
} else {
Greater
}
}
}
#[doc(hidden)]
/// Trait implemented for types that can be compared for equality using
/// their bytewise representation
trait BytewiseEquality { }
macro_rules! impl_marker_for {
($traitname:ident, $($ty:ty)*) => {
$(
impl $traitname for $ty { }
)*
}
}
impl_marker_for!(BytewiseEquality,
u8 i8 u16 i16 u32 i32 u64 i64 usize isize char bool);
#[doc(hidden)]
unsafe impl<'a, T> TrustedRandomAccess for Iter<'a, T> {
unsafe fn get_unchecked(&mut self, i: usize) -> &'a T {
&*self.ptr.offset(i as isize)
}
fn may_have_side_effect() -> bool { false }
}
#[doc(hidden)]
unsafe impl<'a, T> TrustedRandomAccess for IterMut<'a, T> {
unsafe fn get_unchecked(&mut self, i: usize) -> &'a mut T {
&mut *self.ptr.offset(i as isize)
}
fn may_have_side_effect() -> bool { false }
}
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