| // Copyright 2012-2015 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. |
| |
| //! A dynamically-sized view into a contiguous sequence, `[T]`. |
| //! |
| //! Slices are a view into a block of memory represented as a pointer and a |
| //! length. |
| //! |
| //! ``` |
| //! // slicing a Vec |
| //! let vec = vec![1, 2, 3]; |
| //! let int_slice = &vec[..]; |
| //! // coercing an array to a slice |
| //! let str_slice: &[&str] = &["one", "two", "three"]; |
| //! ``` |
| //! |
| //! Slices are either mutable or shared. The shared slice type is `&[T]`, |
| //! while the mutable slice type is `&mut [T]`, where `T` represents the element |
| //! type. For example, you can mutate the block of memory that a mutable slice |
| //! points to: |
| //! |
| //! ``` |
| //! let x = &mut [1, 2, 3]; |
| //! x[1] = 7; |
| //! assert_eq!(x, &[1, 7, 3]); |
| //! ``` |
| //! |
| //! Here are some of the things this module contains: |
| //! |
| //! ## Structs |
| //! |
| //! There are several structs that are useful for slices, such as `Iter`, which |
| //! represents iteration over a slice. |
| //! |
| //! ## Trait Implementations |
| //! |
| //! There are several implementations of common traits for slices. Some examples |
| //! include: |
| //! |
| //! * `Clone` |
| //! * `Eq`, `Ord` - for slices whose element type are `Eq` or `Ord`. |
| //! * `Hash` - for slices whose element type is `Hash` |
| //! |
| //! ## Iteration |
| //! |
| //! The slices implement `IntoIterator`. The iterator yields references to the |
| //! slice elements. |
| //! |
| //! ``` |
| //! let numbers = &[0, 1, 2]; |
| //! for n in numbers { |
| //! println!("{} is a number!", n); |
| //! } |
| //! ``` |
| //! |
| //! The mutable slice yields mutable references to the elements: |
| //! |
| //! ``` |
| //! let mut scores = [7, 8, 9]; |
| //! for score in &mut scores[..] { |
| //! *score += 1; |
| //! } |
| //! ``` |
| //! |
| //! This iterator yields mutable references to the slice's elements, so while |
| //! the element type of the slice is `i32`, the element type of the iterator is |
| //! `&mut i32`. |
| //! |
| //! * `.iter()` and `.iter_mut()` are the explicit methods to return the default |
| //! iterators. |
| //! * Further methods that return iterators are `.split()`, `.splitn()`, |
| //! `.chunks()`, `.windows()` and more. |
| //! |
| //! *[See also the slice primitive type](../../std/primitive.slice.html).* |
| #![stable(feature = "rust1", since = "1.0.0")] |
| |
| // Many of the usings in this module are only used in the test configuration. |
| // It's cleaner to just turn off the unused_imports warning than to fix them. |
| #![cfg_attr(test, allow(unused_imports, dead_code))] |
| |
| use alloc::boxed::Box; |
| use core::cmp::Ordering::{self, Greater, Less}; |
| use core::cmp; |
| use core::mem::size_of; |
| use core::mem; |
| use core::ptr; |
| use core::slice as core_slice; |
| |
| use borrow::{Borrow, BorrowMut, ToOwned}; |
| use vec::Vec; |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub use core::slice::{Chunks, Windows}; |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub use core::slice::{Iter, IterMut}; |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub use core::slice::{SplitMut, ChunksMut, Split}; |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub use core::slice::{SplitN, RSplitN, SplitNMut, RSplitNMut}; |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub use core::slice::{from_raw_parts, from_raw_parts_mut}; |
| |
| //////////////////////////////////////////////////////////////////////////////// |
| // Basic slice extension methods |
| //////////////////////////////////////////////////////////////////////////////// |
| |
| // HACK(japaric) needed for the implementation of `vec!` macro during testing |
| // NB see the hack module in this file for more details |
| #[cfg(test)] |
| pub use self::hack::into_vec; |
| |
| // HACK(japaric) needed for the implementation of `Vec::clone` during testing |
| // NB see the hack module in this file for more details |
| #[cfg(test)] |
| pub use self::hack::to_vec; |
| |
| // HACK(japaric): With cfg(test) `impl [T]` is not available, these three |
| // functions are actually methods that are in `impl [T]` but not in |
| // `core::slice::SliceExt` - we need to supply these functions for the |
| // `test_permutations` test |
| mod hack { |
| use alloc::boxed::Box; |
| use core::mem; |
| |
| #[cfg(test)] |
| use string::ToString; |
| use vec::Vec; |
| |
| pub fn into_vec<T>(mut b: Box<[T]>) -> Vec<T> { |
| unsafe { |
| let xs = Vec::from_raw_parts(b.as_mut_ptr(), b.len(), b.len()); |
| mem::forget(b); |
| xs |
| } |
| } |
| |
| #[inline] |
| pub fn to_vec<T>(s: &[T]) -> Vec<T> |
| where T: Clone |
| { |
| let mut vector = Vec::with_capacity(s.len()); |
| vector.extend_from_slice(s); |
| vector |
| } |
| } |
| |
| #[lang = "slice"] |
| #[cfg(not(test))] |
| impl<T> [T] { |
| /// Returns the number of elements in the slice. |
| /// |
| /// # Example |
| /// |
| /// ``` |
| /// let a = [1, 2, 3]; |
| /// assert_eq!(a.len(), 3); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn len(&self) -> usize { |
| core_slice::SliceExt::len(self) |
| } |
| |
| /// Returns true if the slice has a length of 0 |
| /// |
| /// # Example |
| /// |
| /// ``` |
| /// let a = [1, 2, 3]; |
| /// assert!(!a.is_empty()); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn is_empty(&self) -> bool { |
| core_slice::SliceExt::is_empty(self) |
| } |
| |
| /// Returns the first element of a slice, or `None` if it is empty. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let v = [10, 40, 30]; |
| /// assert_eq!(Some(&10), v.first()); |
| /// |
| /// let w: &[i32] = &[]; |
| /// assert_eq!(None, w.first()); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn first(&self) -> Option<&T> { |
| core_slice::SliceExt::first(self) |
| } |
| |
| /// Returns a mutable pointer to the first element of a slice, or `None` if it is empty. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let x = &mut [0, 1, 2]; |
| /// |
| /// if let Some(first) = x.first_mut() { |
| /// *first = 5; |
| /// } |
| /// assert_eq!(x, &[5, 1, 2]); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn first_mut(&mut self) -> Option<&mut T> { |
| core_slice::SliceExt::first_mut(self) |
| } |
| |
| /// Returns the first and all the rest of the elements of a slice. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let x = &[0, 1, 2]; |
| /// |
| /// if let Some((first, elements)) = x.split_first() { |
| /// assert_eq!(first, &0); |
| /// assert_eq!(elements, &[1, 2]); |
| /// } |
| /// ``` |
| #[stable(feature = "slice_splits", since = "1.5.0")] |
| #[inline] |
| pub fn split_first(&self) -> Option<(&T, &[T])> { |
| core_slice::SliceExt::split_first(self) |
| } |
| |
| /// Returns the first and all the rest of the elements of a slice. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let x = &mut [0, 1, 2]; |
| /// |
| /// if let Some((first, elements)) = x.split_first_mut() { |
| /// *first = 3; |
| /// elements[0] = 4; |
| /// elements[1] = 5; |
| /// } |
| /// assert_eq!(x, &[3, 4, 5]); |
| /// ``` |
| #[stable(feature = "slice_splits", since = "1.5.0")] |
| #[inline] |
| pub fn split_first_mut(&mut self) -> Option<(&mut T, &mut [T])> { |
| core_slice::SliceExt::split_first_mut(self) |
| } |
| |
| /// Returns the last and all the rest of the elements of a slice. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let x = &[0, 1, 2]; |
| /// |
| /// if let Some((last, elements)) = x.split_last() { |
| /// assert_eq!(last, &2); |
| /// assert_eq!(elements, &[0, 1]); |
| /// } |
| /// ``` |
| #[stable(feature = "slice_splits", since = "1.5.0")] |
| #[inline] |
| pub fn split_last(&self) -> Option<(&T, &[T])> { |
| core_slice::SliceExt::split_last(self) |
| |
| } |
| |
| /// Returns the last and all the rest of the elements of a slice. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let x = &mut [0, 1, 2]; |
| /// |
| /// if let Some((last, elements)) = x.split_last_mut() { |
| /// *last = 3; |
| /// elements[0] = 4; |
| /// elements[1] = 5; |
| /// } |
| /// assert_eq!(x, &[4, 5, 3]); |
| /// ``` |
| #[stable(feature = "slice_splits", since = "1.5.0")] |
| #[inline] |
| pub fn split_last_mut(&mut self) -> Option<(&mut T, &mut [T])> { |
| core_slice::SliceExt::split_last_mut(self) |
| } |
| |
| /// Returns the last element of a slice, or `None` if it is empty. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let v = [10, 40, 30]; |
| /// assert_eq!(Some(&30), v.last()); |
| /// |
| /// let w: &[i32] = &[]; |
| /// assert_eq!(None, w.last()); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn last(&self) -> Option<&T> { |
| core_slice::SliceExt::last(self) |
| } |
| |
| /// Returns a mutable pointer to the last item in the slice. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let x = &mut [0, 1, 2]; |
| /// |
| /// if let Some(last) = x.last_mut() { |
| /// *last = 10; |
| /// } |
| /// assert_eq!(x, &[0, 1, 10]); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn last_mut(&mut self) -> Option<&mut T> { |
| core_slice::SliceExt::last_mut(self) |
| } |
| |
| /// Returns the element of a slice at the given index, or `None` if the |
| /// index is out of bounds. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let v = [10, 40, 30]; |
| /// assert_eq!(Some(&40), v.get(1)); |
| /// assert_eq!(None, v.get(3)); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn get(&self, index: usize) -> Option<&T> { |
| core_slice::SliceExt::get(self, index) |
| } |
| |
| /// Returns a mutable reference to the element at the given index. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let x = &mut [0, 1, 2]; |
| /// |
| /// if let Some(elem) = x.get_mut(1) { |
| /// *elem = 42; |
| /// } |
| /// assert_eq!(x, &[0, 42, 2]); |
| /// ``` |
| /// or `None` if the index is out of bounds |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn get_mut(&mut self, index: usize) -> Option<&mut T> { |
| core_slice::SliceExt::get_mut(self, index) |
| } |
| |
| /// Returns a pointer to the element at the given index, without doing |
| /// bounds checking. So use it very carefully! |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let x = &[1, 2, 4]; |
| /// |
| /// unsafe { |
| /// assert_eq!(x.get_unchecked(1), &2); |
| /// } |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub unsafe fn get_unchecked(&self, index: usize) -> &T { |
| core_slice::SliceExt::get_unchecked(self, index) |
| } |
| |
| /// Returns an unsafe mutable pointer to the element in index. So use it |
| /// very carefully! |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let x = &mut [1, 2, 4]; |
| /// |
| /// unsafe { |
| /// let elem = x.get_unchecked_mut(1); |
| /// *elem = 13; |
| /// } |
| /// assert_eq!(x, &[1, 13, 4]); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub unsafe fn get_unchecked_mut(&mut self, index: usize) -> &mut T { |
| core_slice::SliceExt::get_unchecked_mut(self, index) |
| } |
| |
| /// Returns an raw pointer to the slice's buffer |
| /// |
| /// The caller must ensure that the slice outlives the pointer this |
| /// function returns, or else it will end up pointing to garbage. |
| /// |
| /// Modifying the slice may cause its buffer to be reallocated, which |
| /// would also make any pointers to it invalid. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let x = &[1, 2, 4]; |
| /// let x_ptr = x.as_ptr(); |
| /// |
| /// unsafe { |
| /// for i in 0..x.len() { |
| /// assert_eq!(x.get_unchecked(i), &*x_ptr.offset(i as isize)); |
| /// } |
| /// } |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn as_ptr(&self) -> *const T { |
| core_slice::SliceExt::as_ptr(self) |
| } |
| |
| /// Returns an unsafe mutable pointer to the slice's buffer. |
| /// |
| /// The caller must ensure that the slice outlives the pointer this |
| /// function returns, or else it will end up pointing to garbage. |
| /// |
| /// Modifying the slice may cause its buffer to be reallocated, which |
| /// would also make any pointers to it invalid. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let x = &mut [1, 2, 4]; |
| /// let x_ptr = x.as_mut_ptr(); |
| /// |
| /// unsafe { |
| /// for i in 0..x.len() { |
| /// *x_ptr.offset(i as isize) += 2; |
| /// } |
| /// } |
| /// assert_eq!(x, &[3, 4, 6]); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn as_mut_ptr(&mut self) -> *mut T { |
| core_slice::SliceExt::as_mut_ptr(self) |
| } |
| |
| /// Swaps two elements in a slice. |
| /// |
| /// # Arguments |
| /// |
| /// * a - The index of the first element |
| /// * b - The index of the second element |
| /// |
| /// # Panics |
| /// |
| /// Panics if `a` or `b` are out of bounds. |
| /// |
| /// # Examples |
| /// |
| /// ```rust |
| /// let mut v = ["a", "b", "c", "d"]; |
| /// v.swap(1, 3); |
| /// assert!(v == ["a", "d", "c", "b"]); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn swap(&mut self, a: usize, b: usize) { |
| core_slice::SliceExt::swap(self, a, b) |
| } |
| |
| /// Reverse the order of elements in a slice, in place. |
| /// |
| /// # Example |
| /// |
| /// ```rust |
| /// let mut v = [1, 2, 3]; |
| /// v.reverse(); |
| /// assert!(v == [3, 2, 1]); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn reverse(&mut self) { |
| core_slice::SliceExt::reverse(self) |
| } |
| |
| /// Returns an iterator over the slice. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let x = &[1, 2, 4]; |
| /// let mut iterator = x.iter(); |
| /// |
| /// assert_eq!(iterator.next(), Some(&1)); |
| /// assert_eq!(iterator.next(), Some(&2)); |
| /// assert_eq!(iterator.next(), Some(&4)); |
| /// assert_eq!(iterator.next(), None); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn iter(&self) -> Iter<T> { |
| core_slice::SliceExt::iter(self) |
| } |
| |
| /// Returns an iterator that allows modifying each value. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let x = &mut [1, 2, 4]; |
| /// { |
| /// let iterator = x.iter_mut(); |
| /// |
| /// for elem in iterator { |
| /// *elem += 2; |
| /// } |
| /// } |
| /// assert_eq!(x, &[3, 4, 6]); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn iter_mut(&mut self) -> IterMut<T> { |
| core_slice::SliceExt::iter_mut(self) |
| } |
| |
| /// Returns an iterator over all contiguous windows of length |
| /// `size`. The windows overlap. If the slice is shorter than |
| /// `size`, the iterator returns no values. |
| /// |
| /// # Panics |
| /// |
| /// Panics if `size` is 0. |
| /// |
| /// # Example |
| /// |
| /// ``` |
| /// let slice = ['r', 'u', 's', 't']; |
| /// let mut iter = slice.windows(2); |
| /// assert_eq!(iter.next().unwrap(), &['r', 'u']); |
| /// assert_eq!(iter.next().unwrap(), &['u', 's']); |
| /// assert_eq!(iter.next().unwrap(), &['s', 't']); |
| /// assert!(iter.next().is_none()); |
| /// ``` |
| /// |
| /// If the slice is shorter than `size`: |
| /// |
| /// ``` |
| /// let slice = ['f', 'o', 'o']; |
| /// let mut iter = slice.windows(4); |
| /// assert!(iter.next().is_none()); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn windows(&self, size: usize) -> Windows<T> { |
| core_slice::SliceExt::windows(self, size) |
| } |
| |
| /// Returns an iterator over `size` elements of the slice at a |
| /// time. The chunks are slices and do not overlap. If `size` does not divide the |
| /// length of the slice, then the last chunk will not have length |
| /// `size`. |
| /// |
| /// # Panics |
| /// |
| /// Panics if `size` is 0. |
| /// |
| /// # Example |
| /// |
| /// ``` |
| /// let slice = ['l', 'o', 'r', 'e', 'm']; |
| /// let mut iter = slice.chunks(2); |
| /// assert_eq!(iter.next().unwrap(), &['l', 'o']); |
| /// assert_eq!(iter.next().unwrap(), &['r', 'e']); |
| /// assert_eq!(iter.next().unwrap(), &['m']); |
| /// assert!(iter.next().is_none()); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn chunks(&self, size: usize) -> Chunks<T> { |
| core_slice::SliceExt::chunks(self, size) |
| } |
| |
| /// Returns an iterator over `chunk_size` elements of the slice at a time. |
| /// The chunks are mutable slices, and do not overlap. If `chunk_size` does |
| /// not divide the length of the slice, then the last chunk will not |
| /// have length `chunk_size`. |
| /// |
| /// # Panics |
| /// |
| /// Panics if `chunk_size` is 0. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let v = &mut [0, 0, 0, 0, 0]; |
| /// let mut count = 1; |
| /// |
| /// for chunk in v.chunks_mut(2) { |
| /// for elem in chunk.iter_mut() { |
| /// *elem += count; |
| /// } |
| /// count += 1; |
| /// } |
| /// assert_eq!(v, &[1, 1, 2, 2, 3]); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<T> { |
| core_slice::SliceExt::chunks_mut(self, chunk_size) |
| } |
| |
| /// Divides one slice into two at an index. |
| /// |
| /// The first will contain all indices from `[0, mid)` (excluding |
| /// the index `mid` itself) and the second will contain all |
| /// indices from `[mid, len)` (excluding the index `len` itself). |
| /// |
| /// # Panics |
| /// |
| /// Panics if `mid > len`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let v = [10, 40, 30, 20, 50]; |
| /// let (v1, v2) = v.split_at(2); |
| /// assert_eq!([10, 40], v1); |
| /// assert_eq!([30, 20, 50], v2); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn split_at(&self, mid: usize) -> (&[T], &[T]) { |
| core_slice::SliceExt::split_at(self, mid) |
| } |
| |
| /// Divides one `&mut` into two at an index. |
| /// |
| /// The first will contain all indices from `[0, mid)` (excluding |
| /// the index `mid` itself) and the second will contain all |
| /// indices from `[mid, len)` (excluding the index `len` itself). |
| /// |
| /// # Panics |
| /// |
| /// Panics if `mid > len`. |
| /// |
| /// # Examples |
| /// |
| /// ```rust |
| /// let mut v = [1, 2, 3, 4, 5, 6]; |
| /// |
| /// // scoped to restrict the lifetime of the borrows |
| /// { |
| /// let (left, right) = v.split_at_mut(0); |
| /// assert!(left == []); |
| /// assert!(right == [1, 2, 3, 4, 5, 6]); |
| /// } |
| /// |
| /// { |
| /// let (left, right) = v.split_at_mut(2); |
| /// assert!(left == [1, 2]); |
| /// assert!(right == [3, 4, 5, 6]); |
| /// } |
| /// |
| /// { |
| /// let (left, right) = v.split_at_mut(6); |
| /// assert!(left == [1, 2, 3, 4, 5, 6]); |
| /// assert!(right == []); |
| /// } |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn split_at_mut(&mut self, mid: usize) -> (&mut [T], &mut [T]) { |
| core_slice::SliceExt::split_at_mut(self, mid) |
| } |
| |
| /// Returns an iterator over subslices separated by elements that match |
| /// `pred`. The matched element is not contained in the subslices. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let slice = [10, 40, 33, 20]; |
| /// let mut iter = slice.split(|num| num % 3 == 0); |
| /// |
| /// assert_eq!(iter.next().unwrap(), &[10, 40]); |
| /// assert_eq!(iter.next().unwrap(), &[20]); |
| /// assert!(iter.next().is_none()); |
| /// ``` |
| /// |
| /// If the first element is matched, an empty slice will be the first item |
| /// returned by the iterator. Similarly, if the last element in the slice |
| /// is matched, an empty slice will be the last item returned by the |
| /// iterator: |
| /// |
| /// ``` |
| /// let slice = [10, 40, 33]; |
| /// let mut iter = slice.split(|num| num % 3 == 0); |
| /// |
| /// assert_eq!(iter.next().unwrap(), &[10, 40]); |
| /// assert_eq!(iter.next().unwrap(), &[]); |
| /// assert!(iter.next().is_none()); |
| /// ``` |
| /// |
| /// If two matched elements are directly adjacent, an empty slice will be |
| /// present between them: |
| /// |
| /// ``` |
| /// let slice = [10, 6, 33, 20]; |
| /// let mut iter = slice.split(|num| num % 3 == 0); |
| /// |
| /// assert_eq!(iter.next().unwrap(), &[10]); |
| /// assert_eq!(iter.next().unwrap(), &[]); |
| /// assert_eq!(iter.next().unwrap(), &[20]); |
| /// assert!(iter.next().is_none()); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn split<F>(&self, pred: F) -> Split<T, F> |
| where F: FnMut(&T) -> bool |
| { |
| core_slice::SliceExt::split(self, pred) |
| } |
| |
| /// Returns an iterator over mutable subslices separated by elements that |
| /// match `pred`. The matched element is not contained in the subslices. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let mut v = [10, 40, 30, 20, 60, 50]; |
| /// |
| /// for group in v.split_mut(|num| *num % 3 == 0) { |
| /// group[0] = 1; |
| /// } |
| /// assert_eq!(v, [1, 40, 30, 1, 60, 1]); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn split_mut<F>(&mut self, pred: F) -> SplitMut<T, F> |
| where F: FnMut(&T) -> bool |
| { |
| core_slice::SliceExt::split_mut(self, pred) |
| } |
| |
| /// Returns an iterator over subslices separated by elements that match |
| /// `pred`, limited to returning at most `n` items. The matched element is |
| /// not contained in the subslices. |
| /// |
| /// The last element returned, if any, will contain the remainder of the |
| /// slice. |
| /// |
| /// # Examples |
| /// |
| /// Print the slice split once by numbers divisible by 3 (i.e. `[10, 40]`, |
| /// `[20, 60, 50]`): |
| /// |
| /// ``` |
| /// let v = [10, 40, 30, 20, 60, 50]; |
| /// |
| /// for group in v.splitn(2, |num| *num % 3 == 0) { |
| /// println!("{:?}", group); |
| /// } |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn splitn<F>(&self, n: usize, pred: F) -> SplitN<T, F> |
| where F: FnMut(&T) -> bool |
| { |
| core_slice::SliceExt::splitn(self, n, pred) |
| } |
| |
| /// Returns an iterator over subslices separated by elements that match |
| /// `pred`, limited to returning at most `n` items. The matched element is |
| /// not contained in the subslices. |
| /// |
| /// The last element returned, if any, will contain the remainder of the |
| /// slice. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let mut v = [10, 40, 30, 20, 60, 50]; |
| /// |
| /// for group in v.splitn_mut(2, |num| *num % 3 == 0) { |
| /// group[0] = 1; |
| /// } |
| /// assert_eq!(v, [1, 40, 30, 1, 60, 50]); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn splitn_mut<F>(&mut self, n: usize, pred: F) -> SplitNMut<T, F> |
| where F: FnMut(&T) -> bool |
| { |
| core_slice::SliceExt::splitn_mut(self, n, pred) |
| } |
| |
| /// Returns an iterator over subslices separated by elements that match |
| /// `pred` limited to returning at most `n` items. This starts at the end of |
| /// the slice and works backwards. The matched element is not contained in |
| /// the subslices. |
| /// |
| /// The last element returned, if any, will contain the remainder of the |
| /// slice. |
| /// |
| /// # Examples |
| /// |
| /// Print the slice split once, starting from the end, by numbers divisible |
| /// by 3 (i.e. `[50]`, `[10, 40, 30, 20]`): |
| /// |
| /// ``` |
| /// let v = [10, 40, 30, 20, 60, 50]; |
| /// |
| /// for group in v.rsplitn(2, |num| *num % 3 == 0) { |
| /// println!("{:?}", group); |
| /// } |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn rsplitn<F>(&self, n: usize, pred: F) -> RSplitN<T, F> |
| where F: FnMut(&T) -> bool |
| { |
| core_slice::SliceExt::rsplitn(self, n, pred) |
| } |
| |
| /// Returns an iterator over subslices separated by elements that match |
| /// `pred` limited to returning at most `n` items. This starts at the end of |
| /// the slice and works backwards. The matched element is not contained in |
| /// the subslices. |
| /// |
| /// The last element returned, if any, will contain the remainder of the |
| /// slice. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let mut s = [10, 40, 30, 20, 60, 50]; |
| /// |
| /// for group in s.rsplitn_mut(2, |num| *num % 3 == 0) { |
| /// group[0] = 1; |
| /// } |
| /// assert_eq!(s, [1, 40, 30, 20, 60, 1]); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn rsplitn_mut<F>(&mut self, n: usize, pred: F) -> RSplitNMut<T, F> |
| where F: FnMut(&T) -> bool |
| { |
| core_slice::SliceExt::rsplitn_mut(self, n, pred) |
| } |
| |
| /// Returns true if the slice contains an element with the given value. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let v = [10, 40, 30]; |
| /// assert!(v.contains(&30)); |
| /// assert!(!v.contains(&50)); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn contains(&self, x: &T) -> bool |
| where T: PartialEq |
| { |
| core_slice::SliceExt::contains(self, x) |
| } |
| |
| /// Returns true if `needle` is a prefix of the slice. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let v = [10, 40, 30]; |
| /// assert!(v.starts_with(&[10])); |
| /// assert!(v.starts_with(&[10, 40])); |
| /// assert!(!v.starts_with(&[50])); |
| /// assert!(!v.starts_with(&[10, 50])); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn starts_with(&self, needle: &[T]) -> bool |
| where T: PartialEq |
| { |
| core_slice::SliceExt::starts_with(self, needle) |
| } |
| |
| /// Returns true if `needle` is a suffix of the slice. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let v = [10, 40, 30]; |
| /// assert!(v.ends_with(&[30])); |
| /// assert!(v.ends_with(&[40, 30])); |
| /// assert!(!v.ends_with(&[50])); |
| /// assert!(!v.ends_with(&[50, 30])); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn ends_with(&self, needle: &[T]) -> bool |
| where T: PartialEq |
| { |
| core_slice::SliceExt::ends_with(self, needle) |
| } |
| |
| /// Binary search a sorted slice for a given element. |
| /// |
| /// If the value is found then `Ok` is returned, containing the |
| /// index of the matching element; if the value is not found then |
| /// `Err` is returned, containing the index where a matching |
| /// element could be inserted while maintaining sorted order. |
| /// |
| /// # Example |
| /// |
| /// Looks up a series of four elements. The first is found, with a |
| /// uniquely determined position; the second and third are not |
| /// found; the fourth could match any position in `[1,4]`. |
| /// |
| /// ```rust |
| /// let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55]; |
| /// |
| /// assert_eq!(s.binary_search(&13), Ok(9)); |
| /// assert_eq!(s.binary_search(&4), Err(7)); |
| /// assert_eq!(s.binary_search(&100), Err(13)); |
| /// let r = s.binary_search(&1); |
| /// assert!(match r { Ok(1...4) => true, _ => false, }); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn binary_search(&self, x: &T) -> Result<usize, usize> |
| where T: Ord |
| { |
| core_slice::SliceExt::binary_search(self, x) |
| } |
| |
| /// Binary search a sorted slice with a comparator function. |
| /// |
| /// The comparator function should implement an order consistent |
| /// with the sort order of the underlying slice, returning an |
| /// order code that indicates whether its argument is `Less`, |
| /// `Equal` or `Greater` the desired target. |
| /// |
| /// If a matching value is found then returns `Ok`, containing |
| /// the index for the matched element; if no match is found then |
| /// `Err` is returned, containing the index where a matching |
| /// element could be inserted while maintaining sorted order. |
| /// |
| /// # Example |
| /// |
| /// Looks up a series of four elements. The first is found, with a |
| /// uniquely determined position; the second and third are not |
| /// found; the fourth could match any position in `[1,4]`. |
| /// |
| /// ```rust |
| /// let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55]; |
| /// |
| /// let seek = 13; |
| /// assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Ok(9)); |
| /// let seek = 4; |
| /// assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(7)); |
| /// let seek = 100; |
| /// assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(13)); |
| /// let seek = 1; |
| /// let r = s.binary_search_by(|probe| probe.cmp(&seek)); |
| /// assert!(match r { Ok(1...4) => true, _ => false, }); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn binary_search_by<F>(&self, f: F) -> Result<usize, usize> |
| where F: FnMut(&T) -> Ordering |
| { |
| core_slice::SliceExt::binary_search_by(self, f) |
| } |
| |
| /// Binary search a sorted slice with a key extraction function. |
| /// |
| /// Assumes that the slice is sorted by the key, for instance with |
| /// `sort_by_key` using the same key extraction function. |
| /// |
| /// If a matching value is found then returns `Ok`, containing the |
| /// index for the matched element; if no match is found then `Err` |
| /// is returned, containing the index where a matching element could |
| /// be inserted while maintaining sorted order. |
| /// |
| /// # Examples |
| /// |
| /// Looks up a series of four elements in a slice of pairs sorted by |
| /// their second elements. The first is found, with a uniquely |
| /// determined position; the second and third are not found; the |
| /// fourth could match any position in `[1,4]`. |
| /// |
| /// ```rust |
| /// let s = [(0, 0), (2, 1), (4, 1), (5, 1), (3, 1), |
| /// (1, 2), (2, 3), (4, 5), (5, 8), (3, 13), |
| /// (1, 21), (2, 34), (4, 55)]; |
| /// |
| /// assert_eq!(s.binary_search_by_key(&13, |&(a,b)| b), Ok(9)); |
| /// assert_eq!(s.binary_search_by_key(&4, |&(a,b)| b), Err(7)); |
| /// assert_eq!(s.binary_search_by_key(&100, |&(a,b)| b), Err(13)); |
| /// let r = s.binary_search_by_key(&1, |&(a,b)| b); |
| /// assert!(match r { Ok(1...4) => true, _ => false, }); |
| /// ``` |
| #[stable(feature = "slice_binary_search_by_key", since = "1.10.0")] |
| #[inline] |
| pub fn binary_search_by_key<B, F>(&self, b: &B, f: F) -> Result<usize, usize> |
| where F: FnMut(&T) -> B, |
| B: Ord |
| { |
| core_slice::SliceExt::binary_search_by_key(self, b, f) |
| } |
| |
| /// This is equivalent to `self.sort_by(|a, b| a.cmp(b))`. |
| /// |
| /// This sort is stable and `O(n log n)` worst-case but allocates |
| /// approximately `2 * n` where `n` is the length of `self`. |
| /// |
| /// # Examples |
| /// |
| /// ```rust |
| /// let mut v = [-5, 4, 1, -3, 2]; |
| /// |
| /// v.sort(); |
| /// assert!(v == [-5, -3, 1, 2, 4]); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn sort(&mut self) |
| where T: Ord |
| { |
| self.sort_by(|a, b| a.cmp(b)) |
| } |
| |
| /// Sorts the slice, in place, using `key` to extract a key by which to |
| /// order the sort by. |
| /// |
| /// This sort is stable and `O(n log n)` worst-case but allocates |
| /// approximately `2 * n`, where `n` is the length of `self`. |
| /// |
| /// # Examples |
| /// |
| /// ```rust |
| /// let mut v = [-5i32, 4, 1, -3, 2]; |
| /// |
| /// v.sort_by_key(|k| k.abs()); |
| /// assert!(v == [1, 2, -3, 4, -5]); |
| /// ``` |
| #[stable(feature = "slice_sort_by_key", since = "1.7.0")] |
| #[inline] |
| pub fn sort_by_key<B, F>(&mut self, mut f: F) |
| where F: FnMut(&T) -> B, B: Ord |
| { |
| self.sort_by(|a, b| f(a).cmp(&f(b))) |
| } |
| |
| /// Sorts the slice, in place, using `compare` to compare |
| /// elements. |
| /// |
| /// This sort is stable and `O(n log n)` worst-case but allocates |
| /// approximately `2 * n`, where `n` is the length of `self`. |
| /// |
| /// # Examples |
| /// |
| /// ```rust |
| /// let mut v = [5, 4, 1, 3, 2]; |
| /// v.sort_by(|a, b| a.cmp(b)); |
| /// assert!(v == [1, 2, 3, 4, 5]); |
| /// |
| /// // reverse sorting |
| /// v.sort_by(|a, b| b.cmp(a)); |
| /// assert!(v == [5, 4, 3, 2, 1]); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn sort_by<F>(&mut self, compare: F) |
| where F: FnMut(&T, &T) -> Ordering |
| { |
| merge_sort(self, compare) |
| } |
| |
| /// Copies the elements from `src` into `self`. |
| /// |
| /// The length of `src` must be the same as `self`. |
| /// |
| /// # Panics |
| /// |
| /// This function will panic if the two slices have different lengths. |
| /// |
| /// # Example |
| /// |
| /// ```rust |
| /// let mut dst = [0, 0, 0]; |
| /// let src = [1, 2, 3]; |
| /// |
| /// dst.clone_from_slice(&src); |
| /// assert!(dst == [1, 2, 3]); |
| /// ``` |
| #[stable(feature = "clone_from_slice", since = "1.7.0")] |
| pub fn clone_from_slice(&mut self, src: &[T]) where T: Clone { |
| core_slice::SliceExt::clone_from_slice(self, src) |
| } |
| |
| /// Copies all elements from `src` into `self`, using a memcpy. |
| /// |
| /// The length of `src` must be the same as `self`. |
| /// |
| /// # Panics |
| /// |
| /// This function will panic if the two slices have different lengths. |
| /// |
| /// # Example |
| /// |
| /// ```rust |
| /// let mut dst = [0, 0, 0]; |
| /// let src = [1, 2, 3]; |
| /// |
| /// dst.copy_from_slice(&src); |
| /// assert_eq!(src, dst); |
| /// ``` |
| #[stable(feature = "copy_from_slice", since = "1.9.0")] |
| pub fn copy_from_slice(&mut self, src: &[T]) where T: Copy { |
| core_slice::SliceExt::copy_from_slice(self, src) |
| } |
| |
| |
| /// Copies `self` into a new `Vec`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let s = [10, 40, 30]; |
| /// let x = s.to_vec(); |
| /// // Here, `s` and `x` can be modified independently. |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn to_vec(&self) -> Vec<T> |
| where T: Clone |
| { |
| // NB see hack module in this file |
| hack::to_vec(self) |
| } |
| |
| /// Converts `self` into a vector without clones or allocation. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// let s: Box<[i32]> = Box::new([10, 40, 30]); |
| /// let x = s.into_vec(); |
| /// // `s` cannot be used anymore because it has been converted into `x`. |
| /// |
| /// assert_eq!(x, vec!(10, 40, 30)); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn into_vec(self: Box<Self>) -> Vec<T> { |
| // NB see hack module in this file |
| hack::into_vec(self) |
| } |
| } |
| |
| //////////////////////////////////////////////////////////////////////////////// |
| // Extension traits for slices over specific kinds of data |
| //////////////////////////////////////////////////////////////////////////////// |
| #[unstable(feature = "slice_concat_ext", |
| reason = "trait should not have to exist", |
| issue = "27747")] |
| /// An extension trait for concatenating slices |
| pub trait SliceConcatExt<T: ?Sized> { |
| #[unstable(feature = "slice_concat_ext", |
| reason = "trait should not have to exist", |
| issue = "27747")] |
| /// The resulting type after concatenation |
| type Output; |
| |
| /// Flattens a slice of `T` into a single value `Self::Output`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// assert_eq!(["hello", "world"].concat(), "helloworld"); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| fn concat(&self) -> Self::Output; |
| |
| /// Flattens a slice of `T` into a single value `Self::Output`, placing a |
| /// given separator between each. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// assert_eq!(["hello", "world"].join(" "), "hello world"); |
| /// ``` |
| #[stable(feature = "rename_connect_to_join", since = "1.3.0")] |
| fn join(&self, sep: &T) -> Self::Output; |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[rustc_deprecated(since = "1.3.0", reason = "renamed to join")] |
| fn connect(&self, sep: &T) -> Self::Output; |
| } |
| |
| #[unstable(feature = "slice_concat_ext", |
| reason = "trait should not have to exist", |
| issue = "27747")] |
| impl<T: Clone, V: Borrow<[T]>> SliceConcatExt<T> for [V] { |
| type Output = Vec<T>; |
| |
| fn concat(&self) -> Vec<T> { |
| let size = self.iter().fold(0, |acc, v| acc + v.borrow().len()); |
| let mut result = Vec::with_capacity(size); |
| for v in self { |
| result.extend_from_slice(v.borrow()) |
| } |
| result |
| } |
| |
| fn join(&self, sep: &T) -> Vec<T> { |
| let size = self.iter().fold(0, |acc, v| acc + v.borrow().len()); |
| let mut result = Vec::with_capacity(size + self.len()); |
| let mut first = true; |
| for v in self { |
| if first { |
| first = false |
| } else { |
| result.push(sep.clone()) |
| } |
| result.extend_from_slice(v.borrow()) |
| } |
| result |
| } |
| |
| fn connect(&self, sep: &T) -> Vec<T> { |
| self.join(sep) |
| } |
| } |
| |
| //////////////////////////////////////////////////////////////////////////////// |
| // Standard trait implementations for slices |
| //////////////////////////////////////////////////////////////////////////////// |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T> Borrow<[T]> for Vec<T> { |
| fn borrow(&self) -> &[T] { |
| &self[..] |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T> BorrowMut<[T]> for Vec<T> { |
| fn borrow_mut(&mut self) -> &mut [T] { |
| &mut self[..] |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T: Clone> ToOwned for [T] { |
| type Owned = Vec<T>; |
| #[cfg(not(test))] |
| fn to_owned(&self) -> Vec<T> { |
| self.to_vec() |
| } |
| |
| // HACK(japaric): with cfg(test) the inherent `[T]::to_vec`, which is required for this method |
| // definition, is not available. Since we don't require this method for testing purposes, I'll |
| // just stub it |
| // NB see the slice::hack module in slice.rs for more information |
| #[cfg(test)] |
| fn to_owned(&self) -> Vec<T> { |
| panic!("not available with cfg(test)") |
| } |
| } |
| |
| //////////////////////////////////////////////////////////////////////////////// |
| // Sorting |
| //////////////////////////////////////////////////////////////////////////////// |
| |
| fn insertion_sort<T, F>(v: &mut [T], mut compare: F) |
| where F: FnMut(&T, &T) -> Ordering |
| { |
| let len = v.len() as isize; |
| let buf_v = v.as_mut_ptr(); |
| |
| // 1 <= i < len; |
| for i in 1..len { |
| // j satisfies: 0 <= j <= i; |
| let mut j = i; |
| unsafe { |
| // `i` is in bounds. |
| let read_ptr = buf_v.offset(i) as *const T; |
| |
| // find where to insert, we need to do strict <, |
| // rather than <=, to maintain stability. |
| |
| // 0 <= j - 1 < len, so .offset(j - 1) is in bounds. |
| while j > 0 && compare(&*read_ptr, &*buf_v.offset(j - 1)) == Less { |
| j -= 1; |
| } |
| |
| // shift everything to the right, to make space to |
| // insert this value. |
| |
| // j + 1 could be `len` (for the last `i`), but in |
| // that case, `i == j` so we don't copy. The |
| // `.offset(j)` is always in bounds. |
| |
| if i != j { |
| let tmp = ptr::read(read_ptr); |
| ptr::copy(&*buf_v.offset(j), buf_v.offset(j + 1), (i - j) as usize); |
| ptr::copy_nonoverlapping(&tmp, buf_v.offset(j), 1); |
| mem::forget(tmp); |
| } |
| } |
| } |
| } |
| |
| fn merge_sort<T, F>(v: &mut [T], mut compare: F) |
| where F: FnMut(&T, &T) -> Ordering |
| { |
| // warning: this wildly uses unsafe. |
| const BASE_INSERTION: usize = 32; |
| const LARGE_INSERTION: usize = 16; |
| |
| // FIXME #12092: smaller insertion runs seems to make sorting |
| // vectors of large elements a little faster on some platforms, |
| // but hasn't been tested/tuned extensively |
| let insertion = if size_of::<T>() <= 16 { |
| BASE_INSERTION |
| } else { |
| LARGE_INSERTION |
| }; |
| |
| let len = v.len(); |
| |
| // short vectors get sorted in-place via insertion sort to avoid allocations |
| if len <= insertion { |
| insertion_sort(v, compare); |
| return; |
| } |
| |
| // allocate some memory to use as scratch memory, we keep the |
| // length 0 so we can keep shallow copies of the contents of `v` |
| // without risking the dtors running on an object twice if |
| // `compare` panics. |
| let mut working_space = Vec::with_capacity(2 * len); |
| // these both are buffers of length `len`. |
| let mut buf_dat = working_space.as_mut_ptr(); |
| let mut buf_tmp = unsafe { buf_dat.offset(len as isize) }; |
| |
| // length `len`. |
| let buf_v = v.as_ptr(); |
| |
| // step 1. sort short runs with insertion sort. This takes the |
| // values from `v` and sorts them into `buf_dat`, leaving that |
| // with sorted runs of length INSERTION. |
| |
| // We could hardcode the sorting comparisons here, and we could |
| // manipulate/step the pointers themselves, rather than repeatedly |
| // .offset-ing. |
| for start in (0..len).step_by(insertion) { |
| // start <= i < len; |
| for i in start..cmp::min(start + insertion, len) { |
| // j satisfies: start <= j <= i; |
| let mut j = i as isize; |
| unsafe { |
| // `i` is in bounds. |
| let read_ptr = buf_v.offset(i as isize); |
| |
| // find where to insert, we need to do strict <, |
| // rather than <=, to maintain stability. |
| |
| // start <= j - 1 < len, so .offset(j - 1) is in |
| // bounds. |
| while j > start as isize && compare(&*read_ptr, &*buf_dat.offset(j - 1)) == Less { |
| j -= 1; |
| } |
| |
| // shift everything to the right, to make space to |
| // insert this value. |
| |
| // j + 1 could be `len` (for the last `i`), but in |
| // that case, `i == j` so we don't copy. The |
| // `.offset(j)` is always in bounds. |
| ptr::copy(&*buf_dat.offset(j), buf_dat.offset(j + 1), i - j as usize); |
| ptr::copy_nonoverlapping(read_ptr, buf_dat.offset(j), 1); |
| } |
| } |
| } |
| |
| // step 2. merge the sorted runs. |
| let mut width = insertion; |
| while width < len { |
| // merge the sorted runs of length `width` in `buf_dat` two at |
| // a time, placing the result in `buf_tmp`. |
| |
| // 0 <= start <= len. |
| for start in (0..len).step_by(2 * width) { |
| // manipulate pointers directly for speed (rather than |
| // using a `for` loop with `range` and `.offset` inside |
| // that loop). |
| unsafe { |
| // the end of the first run & start of the |
| // second. Offset of `len` is defined, since this is |
| // precisely one byte past the end of the object. |
| let right_start = buf_dat.offset(cmp::min(start + width, len) as isize); |
| // end of the second. Similar reasoning to the above re safety. |
| let right_end_idx = cmp::min(start + 2 * width, len); |
| let right_end = buf_dat.offset(right_end_idx as isize); |
| |
| // the pointers to the elements under consideration |
| // from the two runs. |
| |
| // both of these are in bounds. |
| let mut left = buf_dat.offset(start as isize); |
| let mut right = right_start; |
| |
| // where we're putting the results, it is a run of |
| // length `2*width`, so we step it once for each step |
| // of either `left` or `right`. `buf_tmp` has length |
| // `len`, so these are in bounds. |
| let mut out = buf_tmp.offset(start as isize); |
| let out_end = buf_tmp.offset(right_end_idx as isize); |
| |
| // If left[last] <= right[0], they are already in order: |
| // fast-forward the left side (the right side is handled |
| // in the loop). |
| // If `right` is not empty then left is not empty, and |
| // the offsets are in bounds. |
| if right != right_end && compare(&*right.offset(-1), &*right) != Greater { |
| let elems = (right_start as usize - left as usize) / mem::size_of::<T>(); |
| ptr::copy_nonoverlapping(&*left, out, elems); |
| out = out.offset(elems as isize); |
| left = right_start; |
| } |
| |
| while out < out_end { |
| // Either the left or the right run are exhausted, |
| // so just copy the remainder from the other run |
| // and move on; this gives a huge speed-up (order |
| // of 25%) for mostly sorted vectors (the best |
| // case). |
| if left == right_start { |
| // the number remaining in this run. |
| let elems = (right_end as usize - right as usize) / mem::size_of::<T>(); |
| ptr::copy_nonoverlapping(&*right, out, elems); |
| break; |
| } else if right == right_end { |
| let elems = (right_start as usize - left as usize) / mem::size_of::<T>(); |
| ptr::copy_nonoverlapping(&*left, out, elems); |
| break; |
| } |
| |
| // check which side is smaller, and that's the |
| // next element for the new run. |
| |
| // `left < right_start` and `right < right_end`, |
| // so these are valid. |
| let to_copy = if compare(&*left, &*right) == Greater { |
| step(&mut right) |
| } else { |
| step(&mut left) |
| }; |
| ptr::copy_nonoverlapping(&*to_copy, out, 1); |
| step(&mut out); |
| } |
| } |
| } |
| |
| mem::swap(&mut buf_dat, &mut buf_tmp); |
| |
| width *= 2; |
| } |
| |
| // write the result to `v` in one go, so that there are never two copies |
| // of the same object in `v`. |
| unsafe { |
| ptr::copy_nonoverlapping(&*buf_dat, v.as_mut_ptr(), len); |
| } |
| |
| // increment the pointer, returning the old pointer. |
| #[inline(always)] |
| unsafe fn step<T>(ptr: &mut *mut T) -> *mut T { |
| let old = *ptr; |
| *ptr = ptr.offset(1); |
| old |
| } |
| } |
