2058 lines
65 KiB
Rust
2058 lines
65 KiB
Rust
// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! VecDeque is a double-ended queue, which is implemented with the help of a
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//! growing ring buffer.
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//!
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//! This queue has `O(1)` amortized inserts and removals from both ends of the
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//! container. It also has `O(1)` indexing like a vector. The contained elements
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//! are not required to be copyable, and the queue will be sendable if the
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//! contained type is sendable.
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#![stable(feature = "rust1", since = "1.0.0")]
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use core::prelude::*;
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use core::cmp::Ordering;
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use core::fmt;
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use core::iter::{self, repeat, FromIterator, RandomAccessIterator};
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use core::mem;
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use core::ops::{Index, IndexMut};
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use core::ptr::{self, Unique};
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use core::slice;
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use core::hash::{Hash, Hasher};
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use core::cmp;
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use alloc::heap;
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const INITIAL_CAPACITY: usize = 7; // 2^3 - 1
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const MINIMUM_CAPACITY: usize = 1; // 2 - 1
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/// `VecDeque` is a growable ring buffer, which can be used as a
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/// double-ended queue efficiently.
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///
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/// The "default" usage of this type as a queue is to use `push_back` to add to the queue, and
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/// `pop_front` to remove from the queue. `extend` and `append` push onto the back in this manner,
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/// and iterating over `VecDeque` goes front to back.
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#[stable(feature = "rust1", since = "1.0.0")]
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pub struct VecDeque<T> {
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// tail and head are pointers into the buffer. Tail always points
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// to the first element that could be read, Head always points
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// to where data should be written.
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// If tail == head the buffer is empty. The length of the ringbuffer
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// is defined as the distance between the two.
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tail: usize,
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head: usize,
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cap: usize,
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ptr: Unique<T>,
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<T: Clone> Clone for VecDeque<T> {
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fn clone(&self) -> VecDeque<T> {
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self.iter().cloned().collect()
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<T> Drop for VecDeque<T> {
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fn drop(&mut self) {
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self.clear();
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unsafe {
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if mem::size_of::<T>() != 0 {
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heap::deallocate(*self.ptr as *mut u8,
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self.cap * mem::size_of::<T>(),
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mem::align_of::<T>())
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}
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}
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<T> Default for VecDeque<T> {
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#[inline]
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fn default() -> VecDeque<T> { VecDeque::new() }
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}
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impl<T> VecDeque<T> {
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/// Turn ptr into a slice
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#[inline]
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unsafe fn buffer_as_slice(&self) -> &[T] {
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slice::from_raw_parts(*self.ptr, self.cap)
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}
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/// Turn ptr into a mut slice
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#[inline]
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unsafe fn buffer_as_mut_slice(&mut self) -> &mut [T] {
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slice::from_raw_parts_mut(*self.ptr, self.cap)
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}
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/// Moves an element out of the buffer
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#[inline]
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unsafe fn buffer_read(&mut self, off: usize) -> T {
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ptr::read(self.ptr.offset(off as isize))
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}
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/// Writes an element into the buffer, moving it.
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#[inline]
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unsafe fn buffer_write(&mut self, off: usize, t: T) {
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ptr::write(self.ptr.offset(off as isize), t);
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}
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/// Returns true iff the buffer is at capacity
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#[inline]
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fn is_full(&self) -> bool { self.cap - self.len() == 1 }
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/// Returns the index in the underlying buffer for a given logical element
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/// index.
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#[inline]
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fn wrap_index(&self, idx: usize) -> usize { wrap_index(idx, self.cap) }
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/// Returns the index in the underlying buffer for a given logical element
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/// index + addend.
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#[inline]
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fn wrap_add(&self, idx: usize, addend: usize) -> usize {
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wrap_index(idx.wrapping_add(addend), self.cap)
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}
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/// Returns the index in the underlying buffer for a given logical element
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/// index - subtrahend.
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#[inline]
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fn wrap_sub(&self, idx: usize, subtrahend: usize) -> usize {
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wrap_index(idx.wrapping_sub(subtrahend), self.cap)
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}
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/// Copies a contiguous block of memory len long from src to dst
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#[inline]
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unsafe fn copy(&self, dst: usize, src: usize, len: usize) {
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debug_assert!(dst + len <= self.cap, "dst={} src={} len={} cap={}", dst, src, len,
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self.cap);
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debug_assert!(src + len <= self.cap, "dst={} src={} len={} cap={}", dst, src, len,
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self.cap);
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ptr::copy(
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self.ptr.offset(src as isize),
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self.ptr.offset(dst as isize),
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len);
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}
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/// Copies a contiguous block of memory len long from src to dst
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#[inline]
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unsafe fn copy_nonoverlapping(&self, dst: usize, src: usize, len: usize) {
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debug_assert!(dst + len <= self.cap, "dst={} src={} len={} cap={}", dst, src, len,
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self.cap);
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debug_assert!(src + len <= self.cap, "dst={} src={} len={} cap={}", dst, src, len,
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self.cap);
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ptr::copy_nonoverlapping(
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self.ptr.offset(src as isize),
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self.ptr.offset(dst as isize),
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len);
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}
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}
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impl<T> VecDeque<T> {
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/// Creates an empty `VecDeque`.
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn new() -> VecDeque<T> {
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VecDeque::with_capacity(INITIAL_CAPACITY)
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}
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/// Creates an empty `VecDeque` with space for at least `n` elements.
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn with_capacity(n: usize) -> VecDeque<T> {
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// +1 since the ringbuffer always leaves one space empty
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let cap = cmp::max(n + 1, MINIMUM_CAPACITY + 1).next_power_of_two();
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assert!(cap > n, "capacity overflow");
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let size = cap.checked_mul(mem::size_of::<T>())
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.expect("capacity overflow");
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let ptr = unsafe {
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if mem::size_of::<T>() != 0 {
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let ptr = heap::allocate(size, mem::align_of::<T>()) as *mut T;;
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if ptr.is_null() { ::alloc::oom() }
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Unique::new(ptr)
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} else {
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Unique::new(heap::EMPTY as *mut T)
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}
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};
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VecDeque {
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tail: 0,
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head: 0,
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cap: cap,
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ptr: ptr,
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}
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}
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/// Retrieves an element in the `VecDeque` by index.
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///
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/// # Examples
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///
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/// ```
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/// use std::collections::VecDeque;
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///
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/// let mut buf = VecDeque::new();
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/// buf.push_back(3);
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/// buf.push_back(4);
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/// buf.push_back(5);
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/// assert_eq!(buf.get(1).unwrap(), &4);
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn get(&self, i: usize) -> Option<&T> {
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if i < self.len() {
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let idx = self.wrap_add(self.tail, i);
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unsafe { Some(&*self.ptr.offset(idx as isize)) }
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} else {
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None
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}
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}
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/// Retrieves an element in the `VecDeque` mutably by index.
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///
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/// # Examples
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///
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/// ```
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/// use std::collections::VecDeque;
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///
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/// let mut buf = VecDeque::new();
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/// buf.push_back(3);
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/// buf.push_back(4);
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/// buf.push_back(5);
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/// if let Some(elem) = buf.get_mut(1) {
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/// *elem = 7;
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/// }
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///
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/// assert_eq!(buf[1], 7);
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn get_mut(&mut self, i: usize) -> Option<&mut T> {
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if i < self.len() {
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let idx = self.wrap_add(self.tail, i);
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unsafe { Some(&mut *self.ptr.offset(idx as isize)) }
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} else {
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None
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}
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}
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/// Swaps elements at indices `i` and `j`.
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///
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/// `i` and `j` may be equal.
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///
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/// Fails if there is no element with either index.
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///
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/// # Examples
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///
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/// ```
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/// use std::collections::VecDeque;
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///
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/// let mut buf = VecDeque::new();
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/// buf.push_back(3);
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/// buf.push_back(4);
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/// buf.push_back(5);
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/// buf.swap(0, 2);
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/// assert_eq!(buf[0], 5);
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/// assert_eq!(buf[2], 3);
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn swap(&mut self, i: usize, j: usize) {
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assert!(i < self.len());
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assert!(j < self.len());
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let ri = self.wrap_add(self.tail, i);
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let rj = self.wrap_add(self.tail, j);
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unsafe {
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ptr::swap(self.ptr.offset(ri as isize), self.ptr.offset(rj as isize))
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}
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}
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/// Returns the number of elements the `VecDeque` can hold without
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/// reallocating.
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///
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/// # Examples
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///
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/// ```
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/// use std::collections::VecDeque;
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///
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/// let buf: VecDeque<i32> = VecDeque::with_capacity(10);
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/// assert!(buf.capacity() >= 10);
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/// ```
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#[inline]
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn capacity(&self) -> usize { self.cap - 1 }
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/// Reserves the minimum capacity for exactly `additional` more elements to be inserted in the
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/// given `VecDeque`. Does nothing if the capacity is already sufficient.
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///
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/// Note that the allocator may give the collection more space than it requests. Therefore
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/// capacity can not be relied upon to be precisely minimal. Prefer `reserve` if future
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/// insertions are expected.
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///
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/// # Panics
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///
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/// Panics if the new capacity overflows `usize`.
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///
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/// # Examples
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///
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/// ```
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/// use std::collections::VecDeque;
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///
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/// let mut buf: VecDeque<i32> = vec![1].into_iter().collect();
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/// buf.reserve_exact(10);
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/// assert!(buf.capacity() >= 11);
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn reserve_exact(&mut self, additional: usize) {
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self.reserve(additional);
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}
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/// Reserves capacity for at least `additional` more elements to be inserted in the given
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/// `VecDeque`. The collection may reserve more space to avoid frequent reallocations.
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///
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/// # Panics
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///
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/// Panics if the new capacity overflows `usize`.
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///
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/// # Examples
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///
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/// ```
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/// use std::collections::VecDeque;
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///
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/// let mut buf: VecDeque<i32> = vec![1].into_iter().collect();
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/// buf.reserve(10);
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/// assert!(buf.capacity() >= 11);
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn reserve(&mut self, additional: usize) {
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let new_len = self.len() + additional;
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assert!(new_len + 1 > self.len(), "capacity overflow");
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if new_len > self.capacity() {
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let count = (new_len + 1).next_power_of_two();
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assert!(count >= new_len + 1);
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if mem::size_of::<T>() != 0 {
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let old = self.cap * mem::size_of::<T>();
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let new = count.checked_mul(mem::size_of::<T>())
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.expect("capacity overflow");
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unsafe {
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let ptr = heap::reallocate(*self.ptr as *mut u8,
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old,
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new,
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mem::align_of::<T>()) as *mut T;
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if ptr.is_null() { ::alloc::oom() }
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self.ptr = Unique::new(ptr);
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}
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}
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// Move the shortest contiguous section of the ring buffer
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// T H
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// [o o o o o o o . ]
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// T H
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// A [o o o o o o o . . . . . . . . . ]
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// H T
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// [o o . o o o o o ]
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// T H
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// B [. . . o o o o o o o . . . . . . ]
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// H T
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// [o o o o o . o o ]
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// H T
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// C [o o o o o . . . . . . . . . o o ]
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let oldcap = self.cap;
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self.cap = count;
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if self.tail <= self.head { // A
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// Nop
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} else if self.head < oldcap - self.tail { // B
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unsafe {
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self.copy_nonoverlapping(oldcap, 0, self.head);
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}
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self.head += oldcap;
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debug_assert!(self.head > self.tail);
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} else { // C
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let new_tail = count - (oldcap - self.tail);
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unsafe {
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self.copy_nonoverlapping(new_tail, self.tail, oldcap - self.tail);
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}
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self.tail = new_tail;
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debug_assert!(self.head < self.tail);
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}
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debug_assert!(self.head < self.cap);
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debug_assert!(self.tail < self.cap);
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debug_assert!(self.cap.count_ones() == 1);
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}
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}
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/// Shrinks the capacity of the `VecDeque` as much as possible.
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///
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/// It will drop down as close as possible to the length but the allocator may still inform the
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/// `VecDeque` that there is space for a few more elements.
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///
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/// # Examples
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///
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/// ```
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/// # #![feature(collections)]
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/// use std::collections::VecDeque;
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///
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/// let mut buf = VecDeque::with_capacity(15);
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/// buf.extend(0..4);
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/// assert_eq!(buf.capacity(), 15);
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/// buf.shrink_to_fit();
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/// assert!(buf.capacity() >= 4);
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/// ```
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pub fn shrink_to_fit(&mut self) {
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// +1 since the ringbuffer always leaves one space empty
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// len + 1 can't overflow for an existing, well-formed ringbuffer.
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let target_cap = cmp::max(self.len() + 1, MINIMUM_CAPACITY + 1).next_power_of_two();
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if target_cap < self.cap {
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// There are three cases of interest:
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// All elements are out of desired bounds
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// Elements are contiguous, and head is out of desired bounds
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// Elements are discontiguous, and tail is out of desired bounds
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//
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// At all other times, element positions are unaffected.
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//
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// Indicates that elements at the head should be moved.
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let head_outside = self.head == 0 || self.head >= target_cap;
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// Move elements from out of desired bounds (positions after target_cap)
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if self.tail >= target_cap && head_outside {
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// T H
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// [. . . . . . . . o o o o o o o . ]
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// T H
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// [o o o o o o o . ]
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unsafe {
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self.copy_nonoverlapping(0, self.tail, self.len());
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}
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self.head = self.len();
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self.tail = 0;
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} else if self.tail != 0 && self.tail < target_cap && head_outside {
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// T H
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// [. . . o o o o o o o . . . . . . ]
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// H T
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// [o o . o o o o o ]
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let len = self.wrap_sub(self.head, target_cap);
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unsafe {
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self.copy_nonoverlapping(0, target_cap, len);
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}
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self.head = len;
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debug_assert!(self.head < self.tail);
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} else if self.tail >= target_cap {
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// H T
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// [o o o o o . . . . . . . . . o o ]
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// H T
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// [o o o o o . o o ]
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debug_assert!(self.wrap_sub(self.head, 1) < target_cap);
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let len = self.cap - self.tail;
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let new_tail = target_cap - len;
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unsafe {
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self.copy_nonoverlapping(new_tail, self.tail, len);
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}
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self.tail = new_tail;
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debug_assert!(self.head < self.tail);
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}
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if mem::size_of::<T>() != 0 {
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let old = self.cap * mem::size_of::<T>();
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let new_size = target_cap * mem::size_of::<T>();
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unsafe {
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let ptr = heap::reallocate(*self.ptr as *mut u8,
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old,
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new_size,
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mem::align_of::<T>()) as *mut T;
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if ptr.is_null() { ::alloc::oom() }
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self.ptr = Unique::new(ptr);
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}
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}
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self.cap = target_cap;
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debug_assert!(self.head < self.cap);
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debug_assert!(self.tail < self.cap);
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debug_assert!(self.cap.count_ones() == 1);
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}
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}
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/// Shortens a `VecDeque`, dropping excess elements from the back.
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///
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/// If `len` is greater than the `VecDeque`'s current length, this has no
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/// effect.
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///
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/// # Examples
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///
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/// ```
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/// # #![feature(deque_extras)]
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/// use std::collections::VecDeque;
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///
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/// let mut buf = VecDeque::new();
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/// buf.push_back(5);
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|
/// buf.push_back(10);
|
|
/// buf.push_back(15);
|
|
/// buf.truncate(1);
|
|
/// assert_eq!(buf.len(), 1);
|
|
/// assert_eq!(Some(&5), buf.get(0));
|
|
/// ```
|
|
#[unstable(feature = "deque_extras",
|
|
reason = "matches collection reform specification; waiting on panic semantics")]
|
|
pub fn truncate(&mut self, len: usize) {
|
|
for _ in len..self.len() {
|
|
self.pop_back();
|
|
}
|
|
}
|
|
|
|
/// Returns a front-to-back iterator.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// use std::collections::VecDeque;
|
|
///
|
|
/// let mut buf = VecDeque::new();
|
|
/// buf.push_back(5);
|
|
/// buf.push_back(3);
|
|
/// buf.push_back(4);
|
|
/// let b: &[_] = &[&5, &3, &4];
|
|
/// let c: Vec<&i32> = buf.iter().collect();
|
|
/// assert_eq!(&c[..], b);
|
|
/// ```
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
pub fn iter(&self) -> Iter<T> {
|
|
Iter {
|
|
tail: self.tail,
|
|
head: self.head,
|
|
ring: unsafe { self.buffer_as_slice() }
|
|
}
|
|
}
|
|
|
|
/// Returns a front-to-back iterator that returns mutable references.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// use std::collections::VecDeque;
|
|
///
|
|
/// let mut buf = VecDeque::new();
|
|
/// buf.push_back(5);
|
|
/// buf.push_back(3);
|
|
/// buf.push_back(4);
|
|
/// for num in buf.iter_mut() {
|
|
/// *num = *num - 2;
|
|
/// }
|
|
/// let b: &[_] = &[&mut 3, &mut 1, &mut 2];
|
|
/// assert_eq!(&buf.iter_mut().collect::<Vec<&mut i32>>()[..], b);
|
|
/// ```
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
pub fn iter_mut(&mut self) -> IterMut<T> {
|
|
IterMut {
|
|
tail: self.tail,
|
|
head: self.head,
|
|
ring: unsafe { self.buffer_as_mut_slice() },
|
|
}
|
|
}
|
|
|
|
/// Returns a pair of slices which contain, in order, the contents of the
|
|
/// `VecDeque`.
|
|
#[inline]
|
|
#[unstable(feature = "deque_extras",
|
|
reason = "matches collection reform specification, waiting for dust to settle")]
|
|
pub fn as_slices(&self) -> (&[T], &[T]) {
|
|
unsafe {
|
|
let contiguous = self.is_contiguous();
|
|
let buf = self.buffer_as_slice();
|
|
if contiguous {
|
|
let (empty, buf) = buf.split_at(0);
|
|
(&buf[self.tail..self.head], empty)
|
|
} else {
|
|
let (mid, right) = buf.split_at(self.tail);
|
|
let (left, _) = mid.split_at(self.head);
|
|
(right, left)
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Returns a pair of slices which contain, in order, the contents of the
|
|
/// `VecDeque`.
|
|
#[inline]
|
|
#[unstable(feature = "deque_extras",
|
|
reason = "matches collection reform specification, waiting for dust to settle")]
|
|
pub fn as_mut_slices(&mut self) -> (&mut [T], &mut [T]) {
|
|
unsafe {
|
|
let contiguous = self.is_contiguous();
|
|
let head = self.head;
|
|
let tail = self.tail;
|
|
let buf = self.buffer_as_mut_slice();
|
|
|
|
if contiguous {
|
|
let (empty, buf) = buf.split_at_mut(0);
|
|
(&mut buf[tail .. head], empty)
|
|
} else {
|
|
let (mid, right) = buf.split_at_mut(tail);
|
|
let (left, _) = mid.split_at_mut(head);
|
|
|
|
(right, left)
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Returns the number of elements in the `VecDeque`.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// use std::collections::VecDeque;
|
|
///
|
|
/// let mut v = VecDeque::new();
|
|
/// assert_eq!(v.len(), 0);
|
|
/// v.push_back(1);
|
|
/// assert_eq!(v.len(), 1);
|
|
/// ```
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
pub fn len(&self) -> usize { count(self.tail, self.head, self.cap) }
|
|
|
|
/// Returns true if the buffer contains no elements
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// use std::collections::VecDeque;
|
|
///
|
|
/// let mut v = VecDeque::new();
|
|
/// assert!(v.is_empty());
|
|
/// v.push_front(1);
|
|
/// assert!(!v.is_empty());
|
|
/// ```
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
pub fn is_empty(&self) -> bool { self.len() == 0 }
|
|
|
|
/// Creates a draining iterator that clears the `VecDeque` and iterates over
|
|
/// the removed items from start to end.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// # #![feature(drain)]
|
|
/// use std::collections::VecDeque;
|
|
///
|
|
/// let mut v = VecDeque::new();
|
|
/// v.push_back(1);
|
|
/// assert_eq!(v.drain().next(), Some(1));
|
|
/// assert!(v.is_empty());
|
|
/// ```
|
|
#[inline]
|
|
#[unstable(feature = "drain",
|
|
reason = "matches collection reform specification, waiting for dust to settle")]
|
|
pub fn drain(&mut self) -> Drain<T> {
|
|
Drain {
|
|
inner: self,
|
|
}
|
|
}
|
|
|
|
/// Clears the buffer, removing all values.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// use std::collections::VecDeque;
|
|
///
|
|
/// let mut v = VecDeque::new();
|
|
/// v.push_back(1);
|
|
/// v.clear();
|
|
/// assert!(v.is_empty());
|
|
/// ```
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
#[inline]
|
|
pub fn clear(&mut self) {
|
|
self.drain();
|
|
}
|
|
|
|
/// Provides a reference to the front element, or `None` if the sequence is
|
|
/// empty.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// use std::collections::VecDeque;
|
|
///
|
|
/// let mut d = VecDeque::new();
|
|
/// assert_eq!(d.front(), None);
|
|
///
|
|
/// d.push_back(1);
|
|
/// d.push_back(2);
|
|
/// assert_eq!(d.front(), Some(&1));
|
|
/// ```
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
pub fn front(&self) -> Option<&T> {
|
|
if !self.is_empty() { Some(&self[0]) } else { None }
|
|
}
|
|
|
|
/// Provides a mutable reference to the front element, or `None` if the
|
|
/// sequence is empty.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// use std::collections::VecDeque;
|
|
///
|
|
/// let mut d = VecDeque::new();
|
|
/// assert_eq!(d.front_mut(), None);
|
|
///
|
|
/// d.push_back(1);
|
|
/// d.push_back(2);
|
|
/// match d.front_mut() {
|
|
/// Some(x) => *x = 9,
|
|
/// None => (),
|
|
/// }
|
|
/// assert_eq!(d.front(), Some(&9));
|
|
/// ```
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
pub fn front_mut(&mut self) -> Option<&mut T> {
|
|
if !self.is_empty() { Some(&mut self[0]) } else { None }
|
|
}
|
|
|
|
/// Provides a reference to the back element, or `None` if the sequence is
|
|
/// empty.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// use std::collections::VecDeque;
|
|
///
|
|
/// let mut d = VecDeque::new();
|
|
/// assert_eq!(d.back(), None);
|
|
///
|
|
/// d.push_back(1);
|
|
/// d.push_back(2);
|
|
/// assert_eq!(d.back(), Some(&2));
|
|
/// ```
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
pub fn back(&self) -> Option<&T> {
|
|
if !self.is_empty() { Some(&self[self.len() - 1]) } else { None }
|
|
}
|
|
|
|
/// Provides a mutable reference to the back element, or `None` if the
|
|
/// sequence is empty.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// use std::collections::VecDeque;
|
|
///
|
|
/// let mut d = VecDeque::new();
|
|
/// assert_eq!(d.back(), None);
|
|
///
|
|
/// d.push_back(1);
|
|
/// d.push_back(2);
|
|
/// match d.back_mut() {
|
|
/// Some(x) => *x = 9,
|
|
/// None => (),
|
|
/// }
|
|
/// assert_eq!(d.back(), Some(&9));
|
|
/// ```
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
pub fn back_mut(&mut self) -> Option<&mut T> {
|
|
let len = self.len();
|
|
if !self.is_empty() { Some(&mut self[len - 1]) } else { None }
|
|
}
|
|
|
|
/// Removes the first element and returns it, or `None` if the sequence is
|
|
/// empty.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// use std::collections::VecDeque;
|
|
///
|
|
/// let mut d = VecDeque::new();
|
|
/// d.push_back(1);
|
|
/// d.push_back(2);
|
|
///
|
|
/// assert_eq!(d.pop_front(), Some(1));
|
|
/// assert_eq!(d.pop_front(), Some(2));
|
|
/// assert_eq!(d.pop_front(), None);
|
|
/// ```
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
pub fn pop_front(&mut self) -> Option<T> {
|
|
if self.is_empty() {
|
|
None
|
|
} else {
|
|
let tail = self.tail;
|
|
self.tail = self.wrap_add(self.tail, 1);
|
|
unsafe { Some(self.buffer_read(tail)) }
|
|
}
|
|
}
|
|
|
|
/// Inserts an element first in the sequence.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// use std::collections::VecDeque;
|
|
///
|
|
/// let mut d = VecDeque::new();
|
|
/// d.push_front(1);
|
|
/// d.push_front(2);
|
|
/// assert_eq!(d.front(), Some(&2));
|
|
/// ```
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
pub fn push_front(&mut self, t: T) {
|
|
if self.is_full() {
|
|
self.reserve(1);
|
|
debug_assert!(!self.is_full());
|
|
}
|
|
|
|
self.tail = self.wrap_sub(self.tail, 1);
|
|
let tail = self.tail;
|
|
unsafe { self.buffer_write(tail, t); }
|
|
}
|
|
|
|
/// Appends an element to the back of a buffer
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// use std::collections::VecDeque;
|
|
///
|
|
/// let mut buf = VecDeque::new();
|
|
/// buf.push_back(1);
|
|
/// buf.push_back(3);
|
|
/// assert_eq!(3, *buf.back().unwrap());
|
|
/// ```
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
pub fn push_back(&mut self, t: T) {
|
|
if self.is_full() {
|
|
self.reserve(1);
|
|
debug_assert!(!self.is_full());
|
|
}
|
|
|
|
let head = self.head;
|
|
self.head = self.wrap_add(self.head, 1);
|
|
unsafe { self.buffer_write(head, t) }
|
|
}
|
|
|
|
/// Removes the last element from a buffer and returns it, or `None` if
|
|
/// it is empty.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// use std::collections::VecDeque;
|
|
///
|
|
/// let mut buf = VecDeque::new();
|
|
/// assert_eq!(buf.pop_back(), None);
|
|
/// buf.push_back(1);
|
|
/// buf.push_back(3);
|
|
/// assert_eq!(buf.pop_back(), Some(3));
|
|
/// ```
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
pub fn pop_back(&mut self) -> Option<T> {
|
|
if self.is_empty() {
|
|
None
|
|
} else {
|
|
self.head = self.wrap_sub(self.head, 1);
|
|
let head = self.head;
|
|
unsafe { Some(self.buffer_read(head)) }
|
|
}
|
|
}
|
|
|
|
#[inline]
|
|
fn is_contiguous(&self) -> bool {
|
|
self.tail <= self.head
|
|
}
|
|
|
|
/// Removes an element from anywhere in the `VecDeque` and returns it, replacing it with the
|
|
/// last element.
|
|
///
|
|
/// This does not preserve ordering, but is O(1).
|
|
///
|
|
/// Returns `None` if `index` is out of bounds.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// # #![feature(deque_extras)]
|
|
/// use std::collections::VecDeque;
|
|
///
|
|
/// let mut buf = VecDeque::new();
|
|
/// assert_eq!(buf.swap_back_remove(0), None);
|
|
/// buf.push_back(5);
|
|
/// buf.push_back(99);
|
|
/// buf.push_back(15);
|
|
/// buf.push_back(20);
|
|
/// buf.push_back(10);
|
|
/// assert_eq!(buf.swap_back_remove(1), Some(99));
|
|
/// ```
|
|
#[unstable(feature = "deque_extras",
|
|
reason = "the naming of this function may be altered")]
|
|
pub fn swap_back_remove(&mut self, index: usize) -> Option<T> {
|
|
let length = self.len();
|
|
if length > 0 && index < length - 1 {
|
|
self.swap(index, length - 1);
|
|
} else if index >= length {
|
|
return None;
|
|
}
|
|
self.pop_back()
|
|
}
|
|
|
|
/// Removes an element from anywhere in the `VecDeque` and returns it,
|
|
/// replacing it with the first element.
|
|
///
|
|
/// This does not preserve ordering, but is O(1).
|
|
///
|
|
/// Returns `None` if `index` is out of bounds.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// # #![feature(deque_extras)]
|
|
/// use std::collections::VecDeque;
|
|
///
|
|
/// let mut buf = VecDeque::new();
|
|
/// assert_eq!(buf.swap_front_remove(0), None);
|
|
/// buf.push_back(15);
|
|
/// buf.push_back(5);
|
|
/// buf.push_back(10);
|
|
/// buf.push_back(99);
|
|
/// buf.push_back(20);
|
|
/// assert_eq!(buf.swap_front_remove(3), Some(99));
|
|
/// ```
|
|
#[unstable(feature = "deque_extras",
|
|
reason = "the naming of this function may be altered")]
|
|
pub fn swap_front_remove(&mut self, index: usize) -> Option<T> {
|
|
let length = self.len();
|
|
if length > 0 && index < length && index != 0 {
|
|
self.swap(index, 0);
|
|
} else if index >= length {
|
|
return None;
|
|
}
|
|
self.pop_front()
|
|
}
|
|
|
|
/// Inserts an element at position `i` within the `VecDeque`. Whichever
|
|
/// end is closer to the insertion point will be moved to make room,
|
|
/// and all the affected elements will be moved to new positions.
|
|
///
|
|
/// # Panics
|
|
///
|
|
/// Panics if `i` is greater than `VecDeque`'s length
|
|
///
|
|
/// # Examples
|
|
/// ```
|
|
/// # #![feature(collections)]
|
|
/// use std::collections::VecDeque;
|
|
///
|
|
/// let mut buf = VecDeque::new();
|
|
/// buf.push_back(10);
|
|
/// buf.push_back(12);
|
|
/// buf.insert(1,11);
|
|
/// assert_eq!(Some(&11), buf.get(1));
|
|
/// ```
|
|
pub fn insert(&mut self, i: usize, t: T) {
|
|
assert!(i <= self.len(), "index out of bounds");
|
|
if self.is_full() {
|
|
self.reserve(1);
|
|
debug_assert!(!self.is_full());
|
|
}
|
|
|
|
// Move the least number of elements in the ring buffer and insert
|
|
// the given object
|
|
//
|
|
// At most len/2 - 1 elements will be moved. O(min(n, n-i))
|
|
//
|
|
// There are three main cases:
|
|
// Elements are contiguous
|
|
// - special case when tail is 0
|
|
// Elements are discontiguous and the insert is in the tail section
|
|
// Elements are discontiguous and the insert is in the head section
|
|
//
|
|
// For each of those there are two more cases:
|
|
// Insert is closer to tail
|
|
// Insert is closer to head
|
|
//
|
|
// Key: H - self.head
|
|
// T - self.tail
|
|
// o - Valid element
|
|
// I - Insertion element
|
|
// A - The element that should be after the insertion point
|
|
// M - Indicates element was moved
|
|
|
|
let idx = self.wrap_add(self.tail, i);
|
|
|
|
let distance_to_tail = i;
|
|
let distance_to_head = self.len() - i;
|
|
|
|
let contiguous = self.is_contiguous();
|
|
|
|
match (contiguous, distance_to_tail <= distance_to_head, idx >= self.tail) {
|
|
(true, true, _) if i == 0 => {
|
|
// push_front
|
|
//
|
|
// T
|
|
// I H
|
|
// [A o o o o o o . . . . . . . . .]
|
|
//
|
|
// H T
|
|
// [A o o o o o o o . . . . . I]
|
|
//
|
|
|
|
self.tail = self.wrap_sub(self.tail, 1);
|
|
},
|
|
(true, true, _) => unsafe {
|
|
// contiguous, insert closer to tail:
|
|
//
|
|
// T I H
|
|
// [. . . o o A o o o o . . . . . .]
|
|
//
|
|
// T H
|
|
// [. . o o I A o o o o . . . . . .]
|
|
// M M
|
|
//
|
|
// contiguous, insert closer to tail and tail is 0:
|
|
//
|
|
//
|
|
// T I H
|
|
// [o o A o o o o . . . . . . . . .]
|
|
//
|
|
// H T
|
|
// [o I A o o o o o . . . . . . . o]
|
|
// M M
|
|
|
|
let new_tail = self.wrap_sub(self.tail, 1);
|
|
|
|
self.copy(new_tail, self.tail, 1);
|
|
// Already moved the tail, so we only copy `i - 1` elements.
|
|
self.copy(self.tail, self.tail + 1, i - 1);
|
|
|
|
self.tail = new_tail;
|
|
},
|
|
(true, false, _) => unsafe {
|
|
// contiguous, insert closer to head:
|
|
//
|
|
// T I H
|
|
// [. . . o o o o A o o . . . . . .]
|
|
//
|
|
// T H
|
|
// [. . . o o o o I A o o . . . . .]
|
|
// M M M
|
|
|
|
self.copy(idx + 1, idx, self.head - idx);
|
|
self.head = self.wrap_add(self.head, 1);
|
|
},
|
|
(false, true, true) => unsafe {
|
|
// discontiguous, insert closer to tail, tail section:
|
|
//
|
|
// H T I
|
|
// [o o o o o o . . . . . o o A o o]
|
|
//
|
|
// H T
|
|
// [o o o o o o . . . . o o I A o o]
|
|
// M M
|
|
|
|
self.copy(self.tail - 1, self.tail, i);
|
|
self.tail -= 1;
|
|
},
|
|
(false, false, true) => unsafe {
|
|
// discontiguous, insert closer to head, tail section:
|
|
//
|
|
// H T I
|
|
// [o o . . . . . . . o o o o o A o]
|
|
//
|
|
// H T
|
|
// [o o o . . . . . . o o o o o I A]
|
|
// M M M M
|
|
|
|
// copy elements up to new head
|
|
self.copy(1, 0, self.head);
|
|
|
|
// copy last element into empty spot at bottom of buffer
|
|
self.copy(0, self.cap - 1, 1);
|
|
|
|
// move elements from idx to end forward not including ^ element
|
|
self.copy(idx + 1, idx, self.cap - 1 - idx);
|
|
|
|
self.head += 1;
|
|
},
|
|
(false, true, false) if idx == 0 => unsafe {
|
|
// discontiguous, insert is closer to tail, head section,
|
|
// and is at index zero in the internal buffer:
|
|
//
|
|
// I H T
|
|
// [A o o o o o o o o o . . . o o o]
|
|
//
|
|
// H T
|
|
// [A o o o o o o o o o . . o o o I]
|
|
// M M M
|
|
|
|
// copy elements up to new tail
|
|
self.copy(self.tail - 1, self.tail, self.cap - self.tail);
|
|
|
|
// copy last element into empty spot at bottom of buffer
|
|
self.copy(self.cap - 1, 0, 1);
|
|
|
|
self.tail -= 1;
|
|
},
|
|
(false, true, false) => unsafe {
|
|
// discontiguous, insert closer to tail, head section:
|
|
//
|
|
// I H T
|
|
// [o o o A o o o o o o . . . o o o]
|
|
//
|
|
// H T
|
|
// [o o I A o o o o o o . . o o o o]
|
|
// M M M M M M
|
|
|
|
// copy elements up to new tail
|
|
self.copy(self.tail - 1, self.tail, self.cap - self.tail);
|
|
|
|
// copy last element into empty spot at bottom of buffer
|
|
self.copy(self.cap - 1, 0, 1);
|
|
|
|
// move elements from idx-1 to end forward not including ^ element
|
|
self.copy(0, 1, idx - 1);
|
|
|
|
self.tail -= 1;
|
|
},
|
|
(false, false, false) => unsafe {
|
|
// discontiguous, insert closer to head, head section:
|
|
//
|
|
// I H T
|
|
// [o o o o A o o . . . . . . o o o]
|
|
//
|
|
// H T
|
|
// [o o o o I A o o . . . . . o o o]
|
|
// M M M
|
|
|
|
self.copy(idx + 1, idx, self.head - idx);
|
|
self.head += 1;
|
|
}
|
|
}
|
|
|
|
// tail might've been changed so we need to recalculate
|
|
let new_idx = self.wrap_add(self.tail, i);
|
|
unsafe {
|
|
self.buffer_write(new_idx, t);
|
|
}
|
|
}
|
|
|
|
/// Removes and returns the element at position `i` from the `VecDeque`.
|
|
/// Whichever end is closer to the removal point will be moved to make
|
|
/// room, and all the affected elements will be moved to new positions.
|
|
/// Returns `None` if `i` is out of bounds.
|
|
///
|
|
/// # Examples
|
|
/// ```
|
|
/// use std::collections::VecDeque;
|
|
///
|
|
/// let mut buf = VecDeque::new();
|
|
/// buf.push_back(5);
|
|
/// buf.push_back(10);
|
|
/// buf.push_back(12);
|
|
/// buf.push_back(15);
|
|
/// buf.remove(2);
|
|
/// assert_eq!(Some(&15), buf.get(2));
|
|
/// ```
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
pub fn remove(&mut self, i: usize) -> Option<T> {
|
|
if self.is_empty() || self.len() <= i {
|
|
return None;
|
|
}
|
|
|
|
// There are three main cases:
|
|
// Elements are contiguous
|
|
// Elements are discontiguous and the removal is in the tail section
|
|
// Elements are discontiguous and the removal is in the head section
|
|
// - special case when elements are technically contiguous,
|
|
// but self.head = 0
|
|
//
|
|
// For each of those there are two more cases:
|
|
// Insert is closer to tail
|
|
// Insert is closer to head
|
|
//
|
|
// Key: H - self.head
|
|
// T - self.tail
|
|
// o - Valid element
|
|
// x - Element marked for removal
|
|
// R - Indicates element that is being removed
|
|
// M - Indicates element was moved
|
|
|
|
let idx = self.wrap_add(self.tail, i);
|
|
|
|
let elem = unsafe {
|
|
Some(self.buffer_read(idx))
|
|
};
|
|
|
|
let distance_to_tail = i;
|
|
let distance_to_head = self.len() - i;
|
|
|
|
let contiguous = self.is_contiguous();
|
|
|
|
match (contiguous, distance_to_tail <= distance_to_head, idx >= self.tail) {
|
|
(true, true, _) => unsafe {
|
|
// contiguous, remove closer to tail:
|
|
//
|
|
// T R H
|
|
// [. . . o o x o o o o . . . . . .]
|
|
//
|
|
// T H
|
|
// [. . . . o o o o o o . . . . . .]
|
|
// M M
|
|
|
|
self.copy(self.tail + 1, self.tail, i);
|
|
self.tail += 1;
|
|
},
|
|
(true, false, _) => unsafe {
|
|
// contiguous, remove closer to head:
|
|
//
|
|
// T R H
|
|
// [. . . o o o o x o o . . . . . .]
|
|
//
|
|
// T H
|
|
// [. . . o o o o o o . . . . . . .]
|
|
// M M
|
|
|
|
self.copy(idx, idx + 1, self.head - idx - 1);
|
|
self.head -= 1;
|
|
},
|
|
(false, true, true) => unsafe {
|
|
// discontiguous, remove closer to tail, tail section:
|
|
//
|
|
// H T R
|
|
// [o o o o o o . . . . . o o x o o]
|
|
//
|
|
// H T
|
|
// [o o o o o o . . . . . . o o o o]
|
|
// M M
|
|
|
|
self.copy(self.tail + 1, self.tail, i);
|
|
self.tail = self.wrap_add(self.tail, 1);
|
|
},
|
|
(false, false, false) => unsafe {
|
|
// discontiguous, remove closer to head, head section:
|
|
//
|
|
// R H T
|
|
// [o o o o x o o . . . . . . o o o]
|
|
//
|
|
// H T
|
|
// [o o o o o o . . . . . . . o o o]
|
|
// M M
|
|
|
|
self.copy(idx, idx + 1, self.head - idx - 1);
|
|
self.head -= 1;
|
|
},
|
|
(false, false, true) => unsafe {
|
|
// discontiguous, remove closer to head, tail section:
|
|
//
|
|
// H T R
|
|
// [o o o . . . . . . o o o o o x o]
|
|
//
|
|
// H T
|
|
// [o o . . . . . . . o o o o o o o]
|
|
// M M M M
|
|
//
|
|
// or quasi-discontiguous, remove next to head, tail section:
|
|
//
|
|
// H T R
|
|
// [. . . . . . . . . o o o o o x o]
|
|
//
|
|
// T H
|
|
// [. . . . . . . . . o o o o o o .]
|
|
// M
|
|
|
|
// draw in elements in the tail section
|
|
self.copy(idx, idx + 1, self.cap - idx - 1);
|
|
|
|
// Prevents underflow.
|
|
if self.head != 0 {
|
|
// copy first element into empty spot
|
|
self.copy(self.cap - 1, 0, 1);
|
|
|
|
// move elements in the head section backwards
|
|
self.copy(0, 1, self.head - 1);
|
|
}
|
|
|
|
self.head = self.wrap_sub(self.head, 1);
|
|
},
|
|
(false, true, false) => unsafe {
|
|
// discontiguous, remove closer to tail, head section:
|
|
//
|
|
// R H T
|
|
// [o o x o o o o o o o . . . o o o]
|
|
//
|
|
// H T
|
|
// [o o o o o o o o o o . . . . o o]
|
|
// M M M M M
|
|
|
|
// draw in elements up to idx
|
|
self.copy(1, 0, idx);
|
|
|
|
// copy last element into empty spot
|
|
self.copy(0, self.cap - 1, 1);
|
|
|
|
// move elements from tail to end forward, excluding the last one
|
|
self.copy(self.tail + 1, self.tail, self.cap - self.tail - 1);
|
|
|
|
self.tail = self.wrap_add(self.tail, 1);
|
|
}
|
|
}
|
|
|
|
return elem;
|
|
}
|
|
|
|
/// Splits the collection into two at the given index.
|
|
///
|
|
/// Returns a newly allocated `Self`. `self` contains elements `[0, at)`,
|
|
/// and the returned `Self` contains elements `[at, len)`.
|
|
///
|
|
/// Note that the capacity of `self` does not change.
|
|
///
|
|
/// # Panics
|
|
///
|
|
/// Panics if `at > len`
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// # #![feature(split_off)]
|
|
/// use std::collections::VecDeque;
|
|
///
|
|
/// let mut buf: VecDeque<_> = vec![1,2,3].into_iter().collect();
|
|
/// let buf2 = buf.split_off(1);
|
|
/// // buf = [1], buf2 = [2, 3]
|
|
/// assert_eq!(buf.len(), 1);
|
|
/// assert_eq!(buf2.len(), 2);
|
|
/// ```
|
|
#[inline]
|
|
#[unstable(feature = "split_off",
|
|
reason = "new API, waiting for dust to settle")]
|
|
pub fn split_off(&mut self, at: usize) -> Self {
|
|
let len = self.len();
|
|
assert!(at <= len, "`at` out of bounds");
|
|
|
|
let other_len = len - at;
|
|
let mut other = VecDeque::with_capacity(other_len);
|
|
|
|
unsafe {
|
|
let (first_half, second_half) = self.as_slices();
|
|
|
|
let first_len = first_half.len();
|
|
let second_len = second_half.len();
|
|
if at < first_len {
|
|
// `at` lies in the first half.
|
|
let amount_in_first = first_len - at;
|
|
|
|
ptr::copy_nonoverlapping(first_half.as_ptr().offset(at as isize),
|
|
*other.ptr,
|
|
amount_in_first);
|
|
|
|
// just take all of the second half.
|
|
ptr::copy_nonoverlapping(second_half.as_ptr(),
|
|
other.ptr.offset(amount_in_first as isize),
|
|
second_len);
|
|
} else {
|
|
// `at` lies in the second half, need to factor in the elements we skipped
|
|
// in the first half.
|
|
let offset = at - first_len;
|
|
let amount_in_second = second_len - offset;
|
|
ptr::copy_nonoverlapping(second_half.as_ptr().offset(offset as isize),
|
|
*other.ptr,
|
|
amount_in_second);
|
|
}
|
|
}
|
|
|
|
// Cleanup where the ends of the buffers are
|
|
self.head = self.wrap_sub(self.head, other_len);
|
|
other.head = other.wrap_index(other_len);
|
|
|
|
other
|
|
}
|
|
|
|
/// Moves all the elements of `other` into `Self`, leaving `other` empty.
|
|
///
|
|
/// # Panics
|
|
///
|
|
/// Panics if the new number of elements in self overflows a `usize`.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// # #![feature(append)]
|
|
/// use std::collections::VecDeque;
|
|
///
|
|
/// let mut buf: VecDeque<_> = vec![1, 2, 3].into_iter().collect();
|
|
/// let mut buf2: VecDeque<_> = vec![4, 5, 6].into_iter().collect();
|
|
/// buf.append(&mut buf2);
|
|
/// assert_eq!(buf.len(), 6);
|
|
/// assert_eq!(buf2.len(), 0);
|
|
/// ```
|
|
#[inline]
|
|
#[unstable(feature = "append",
|
|
reason = "new API, waiting for dust to settle")]
|
|
pub fn append(&mut self, other: &mut Self) {
|
|
// naive impl
|
|
self.extend(other.drain());
|
|
}
|
|
|
|
/// Retains only the elements specified by the predicate.
|
|
///
|
|
/// In other words, remove all elements `e` such that `f(&e)` returns false.
|
|
/// This method operates in place and preserves the order of the retained
|
|
/// elements.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// # #![feature(vec_deque_retain)]
|
|
/// use std::collections::VecDeque;
|
|
///
|
|
/// let mut buf = VecDeque::new();
|
|
/// buf.extend(1..5);
|
|
/// buf.retain(|&x| x%2 == 0);
|
|
///
|
|
/// let v: Vec<_> = buf.into_iter().collect();
|
|
/// assert_eq!(&v[..], &[2, 4]);
|
|
/// ```
|
|
#[unstable(feature = "vec_deque_retain",
|
|
reason = "new API, waiting for dust to settle")]
|
|
pub fn retain<F>(&mut self, mut f: F) where F: FnMut(&T) -> bool {
|
|
let len = self.len();
|
|
let mut del = 0;
|
|
for i in 0..len {
|
|
if !f(&self[i]) {
|
|
del += 1;
|
|
} else if del > 0 {
|
|
self.swap(i-del, i);
|
|
}
|
|
}
|
|
if del > 0 {
|
|
self.truncate(len - del);
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<T: Clone> VecDeque<T> {
|
|
/// Modifies the `VecDeque` in-place so that `len()` is equal to new_len,
|
|
/// either by removing excess elements or by appending copies of a value to the back.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// # #![feature(deque_extras)]
|
|
/// use std::collections::VecDeque;
|
|
///
|
|
/// let mut buf = VecDeque::new();
|
|
/// buf.push_back(5);
|
|
/// buf.push_back(10);
|
|
/// buf.push_back(15);
|
|
/// buf.resize(2, 0);
|
|
/// buf.resize(6, 20);
|
|
/// for (a, b) in [5, 10, 20, 20, 20, 20].iter().zip(&buf) {
|
|
/// assert_eq!(a, b);
|
|
/// }
|
|
/// ```
|
|
#[unstable(feature = "deque_extras",
|
|
reason = "matches collection reform specification; waiting on panic semantics")]
|
|
pub fn resize(&mut self, new_len: usize, value: T) {
|
|
let len = self.len();
|
|
|
|
if new_len > len {
|
|
self.extend(repeat(value).take(new_len - len))
|
|
} else {
|
|
self.truncate(new_len);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Returns the index in the underlying buffer for a given logical element index.
|
|
#[inline]
|
|
fn wrap_index(index: usize, size: usize) -> usize {
|
|
// size is always a power of 2
|
|
index & (size - 1)
|
|
}
|
|
|
|
/// Calculate the number of elements left to be read in the buffer
|
|
#[inline]
|
|
fn count(tail: usize, head: usize, size: usize) -> usize {
|
|
// size is always a power of 2
|
|
(head.wrapping_sub(tail)) & (size - 1)
|
|
}
|
|
|
|
/// `VecDeque` iterator.
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
pub struct Iter<'a, T:'a> {
|
|
ring: &'a [T],
|
|
tail: usize,
|
|
head: usize
|
|
}
|
|
|
|
// FIXME(#19839) Remove in favor of `#[derive(Clone)]`
|
|
impl<'a, T> Clone for Iter<'a, T> {
|
|
fn clone(&self) -> Iter<'a, T> {
|
|
Iter {
|
|
ring: self.ring,
|
|
tail: self.tail,
|
|
head: self.head
|
|
}
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<'a, T> Iterator for Iter<'a, T> {
|
|
type Item = &'a T;
|
|
|
|
#[inline]
|
|
fn next(&mut self) -> Option<&'a T> {
|
|
if self.tail == self.head {
|
|
return None;
|
|
}
|
|
let tail = self.tail;
|
|
self.tail = wrap_index(self.tail.wrapping_add(1), self.ring.len());
|
|
unsafe { Some(self.ring.get_unchecked(tail)) }
|
|
}
|
|
|
|
#[inline]
|
|
fn size_hint(&self) -> (usize, Option<usize>) {
|
|
let len = count(self.tail, self.head, self.ring.len());
|
|
(len, Some(len))
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<'a, T> DoubleEndedIterator for Iter<'a, T> {
|
|
#[inline]
|
|
fn next_back(&mut self) -> Option<&'a T> {
|
|
if self.tail == self.head {
|
|
return None;
|
|
}
|
|
self.head = wrap_index(self.head.wrapping_sub(1), self.ring.len());
|
|
unsafe { Some(self.ring.get_unchecked(self.head)) }
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<'a, T> ExactSizeIterator for Iter<'a, T> {}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
#[allow(deprecated)]
|
|
impl<'a, T> RandomAccessIterator for Iter<'a, T> {
|
|
#[inline]
|
|
fn indexable(&self) -> usize {
|
|
let (len, _) = self.size_hint();
|
|
len
|
|
}
|
|
|
|
#[inline]
|
|
fn idx(&mut self, j: usize) -> Option<&'a T> {
|
|
if j >= self.indexable() {
|
|
None
|
|
} else {
|
|
let idx = wrap_index(self.tail.wrapping_add(j), self.ring.len());
|
|
unsafe { Some(self.ring.get_unchecked(idx)) }
|
|
}
|
|
}
|
|
}
|
|
|
|
/// `VecDeque` mutable iterator.
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
pub struct IterMut<'a, T:'a> {
|
|
ring: &'a mut [T],
|
|
tail: usize,
|
|
head: usize,
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<'a, T> Iterator for IterMut<'a, T> {
|
|
type Item = &'a mut T;
|
|
|
|
#[inline]
|
|
fn next(&mut self) -> Option<&'a mut T> {
|
|
if self.tail == self.head {
|
|
return None;
|
|
}
|
|
let tail = self.tail;
|
|
self.tail = wrap_index(self.tail.wrapping_add(1), self.ring.len());
|
|
|
|
unsafe {
|
|
let elem = self.ring.get_unchecked_mut(tail);
|
|
Some(&mut *(elem as *mut _))
|
|
}
|
|
}
|
|
|
|
#[inline]
|
|
fn size_hint(&self) -> (usize, Option<usize>) {
|
|
let len = count(self.tail, self.head, self.ring.len());
|
|
(len, Some(len))
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<'a, T> DoubleEndedIterator for IterMut<'a, T> {
|
|
#[inline]
|
|
fn next_back(&mut self) -> Option<&'a mut T> {
|
|
if self.tail == self.head {
|
|
return None;
|
|
}
|
|
self.head = wrap_index(self.head.wrapping_sub(1), self.ring.len());
|
|
|
|
unsafe {
|
|
let elem = self.ring.get_unchecked_mut(self.head);
|
|
Some(&mut *(elem as *mut _))
|
|
}
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<'a, T> ExactSizeIterator for IterMut<'a, T> {}
|
|
|
|
/// A by-value VecDeque iterator
|
|
#[derive(Clone)]
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
pub struct IntoIter<T> {
|
|
inner: VecDeque<T>,
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<T> Iterator for IntoIter<T> {
|
|
type Item = T;
|
|
|
|
#[inline]
|
|
fn next(&mut self) -> Option<T> {
|
|
self.inner.pop_front()
|
|
}
|
|
|
|
#[inline]
|
|
fn size_hint(&self) -> (usize, Option<usize>) {
|
|
let len = self.inner.len();
|
|
(len, Some(len))
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<T> DoubleEndedIterator for IntoIter<T> {
|
|
#[inline]
|
|
fn next_back(&mut self) -> Option<T> {
|
|
self.inner.pop_back()
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<T> ExactSizeIterator for IntoIter<T> {}
|
|
|
|
/// A draining VecDeque iterator
|
|
#[unstable(feature = "drain",
|
|
reason = "matches collection reform specification, waiting for dust to settle")]
|
|
pub struct Drain<'a, T: 'a> {
|
|
inner: &'a mut VecDeque<T>,
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<'a, T: 'a> Drop for Drain<'a, T> {
|
|
fn drop(&mut self) {
|
|
for _ in self.by_ref() {}
|
|
self.inner.head = 0;
|
|
self.inner.tail = 0;
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<'a, T: 'a> Iterator for Drain<'a, T> {
|
|
type Item = T;
|
|
|
|
#[inline]
|
|
fn next(&mut self) -> Option<T> {
|
|
self.inner.pop_front()
|
|
}
|
|
|
|
#[inline]
|
|
fn size_hint(&self) -> (usize, Option<usize>) {
|
|
let len = self.inner.len();
|
|
(len, Some(len))
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<'a, T: 'a> DoubleEndedIterator for Drain<'a, T> {
|
|
#[inline]
|
|
fn next_back(&mut self) -> Option<T> {
|
|
self.inner.pop_back()
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<'a, T: 'a> ExactSizeIterator for Drain<'a, T> {}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<A: PartialEq> PartialEq for VecDeque<A> {
|
|
fn eq(&self, other: &VecDeque<A>) -> bool {
|
|
self.len() == other.len() &&
|
|
self.iter().zip(other).all(|(a, b)| a.eq(b))
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<A: Eq> Eq for VecDeque<A> {}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<A: PartialOrd> PartialOrd for VecDeque<A> {
|
|
fn partial_cmp(&self, other: &VecDeque<A>) -> Option<Ordering> {
|
|
iter::order::partial_cmp(self.iter(), other.iter())
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<A: Ord> Ord for VecDeque<A> {
|
|
#[inline]
|
|
fn cmp(&self, other: &VecDeque<A>) -> Ordering {
|
|
iter::order::cmp(self.iter(), other.iter())
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<A: Hash> Hash for VecDeque<A> {
|
|
fn hash<H: Hasher>(&self, state: &mut H) {
|
|
self.len().hash(state);
|
|
for elt in self {
|
|
elt.hash(state);
|
|
}
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<A> Index<usize> for VecDeque<A> {
|
|
type Output = A;
|
|
|
|
#[inline]
|
|
fn index(&self, i: usize) -> &A {
|
|
self.get(i).expect("Out of bounds access")
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<A> IndexMut<usize> for VecDeque<A> {
|
|
#[inline]
|
|
fn index_mut(&mut self, i: usize) -> &mut A {
|
|
self.get_mut(i).expect("Out of bounds access")
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<A> FromIterator<A> for VecDeque<A> {
|
|
fn from_iter<T: IntoIterator<Item=A>>(iterable: T) -> VecDeque<A> {
|
|
let iterator = iterable.into_iter();
|
|
let (lower, _) = iterator.size_hint();
|
|
let mut deq = VecDeque::with_capacity(lower);
|
|
deq.extend(iterator);
|
|
deq
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<T> IntoIterator for VecDeque<T> {
|
|
type Item = T;
|
|
type IntoIter = IntoIter<T>;
|
|
|
|
/// Consumes the list into a front-to-back iterator yielding elements by
|
|
/// value.
|
|
fn into_iter(self) -> IntoIter<T> {
|
|
IntoIter {
|
|
inner: self,
|
|
}
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<'a, T> IntoIterator for &'a VecDeque<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 VecDeque<T> {
|
|
type Item = &'a mut T;
|
|
type IntoIter = IterMut<'a, T>;
|
|
|
|
fn into_iter(mut self) -> IterMut<'a, T> {
|
|
self.iter_mut()
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<A> Extend<A> for VecDeque<A> {
|
|
fn extend<T: IntoIterator<Item=A>>(&mut self, iter: T) {
|
|
for elt in iter {
|
|
self.push_back(elt);
|
|
}
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "extend_ref", since = "1.2.0")]
|
|
impl<'a, T: 'a + Copy> Extend<&'a T> for VecDeque<T> {
|
|
fn extend<I: IntoIterator<Item=&'a T>>(&mut self, iter: I) {
|
|
self.extend(iter.into_iter().cloned());
|
|
}
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl<T: fmt::Debug> fmt::Debug for VecDeque<T> {
|
|
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
|
|
try!(write!(f, "["));
|
|
|
|
for (i, e) in self.iter().enumerate() {
|
|
if i != 0 { try!(write!(f, ", ")); }
|
|
try!(write!(f, "{:?}", *e));
|
|
}
|
|
|
|
write!(f, "]")
|
|
}
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod tests {
|
|
use core::iter::Iterator;
|
|
use core::option::Option::Some;
|
|
|
|
use test;
|
|
|
|
use super::VecDeque;
|
|
|
|
#[bench]
|
|
fn bench_push_back_100(b: &mut test::Bencher) {
|
|
let mut deq = VecDeque::with_capacity(101);
|
|
b.iter(|| {
|
|
for i in 0..100 {
|
|
deq.push_back(i);
|
|
}
|
|
deq.head = 0;
|
|
deq.tail = 0;
|
|
})
|
|
}
|
|
|
|
#[bench]
|
|
fn bench_push_front_100(b: &mut test::Bencher) {
|
|
let mut deq = VecDeque::with_capacity(101);
|
|
b.iter(|| {
|
|
for i in 0..100 {
|
|
deq.push_front(i);
|
|
}
|
|
deq.head = 0;
|
|
deq.tail = 0;
|
|
})
|
|
}
|
|
|
|
#[bench]
|
|
fn bench_pop_back_100(b: &mut test::Bencher) {
|
|
let mut deq= VecDeque::<i32>::with_capacity(101);
|
|
|
|
b.iter(|| {
|
|
deq.head = 100;
|
|
deq.tail = 0;
|
|
while !deq.is_empty() {
|
|
test::black_box(deq.pop_back());
|
|
}
|
|
})
|
|
}
|
|
|
|
#[bench]
|
|
fn bench_pop_front_100(b: &mut test::Bencher) {
|
|
let mut deq = VecDeque::<i32>::with_capacity(101);
|
|
|
|
b.iter(|| {
|
|
deq.head = 100;
|
|
deq.tail = 0;
|
|
while !deq.is_empty() {
|
|
test::black_box(deq.pop_front());
|
|
}
|
|
})
|
|
}
|
|
|
|
#[test]
|
|
fn test_swap_front_back_remove() {
|
|
fn test(back: bool) {
|
|
// This test checks that every single combination of tail position and length is tested.
|
|
// Capacity 15 should be large enough to cover every case.
|
|
let mut tester = VecDeque::with_capacity(15);
|
|
let usable_cap = tester.capacity();
|
|
let final_len = usable_cap / 2;
|
|
|
|
for len in 0..final_len {
|
|
let expected = if back {
|
|
(0..len).collect()
|
|
} else {
|
|
(0..len).rev().collect()
|
|
};
|
|
for tail_pos in 0..usable_cap {
|
|
tester.tail = tail_pos;
|
|
tester.head = tail_pos;
|
|
if back {
|
|
for i in 0..len * 2 {
|
|
tester.push_front(i);
|
|
}
|
|
for i in 0..len {
|
|
assert_eq!(tester.swap_back_remove(i), Some(len * 2 - 1 - i));
|
|
}
|
|
} else {
|
|
for i in 0..len * 2 {
|
|
tester.push_back(i);
|
|
}
|
|
for i in 0..len {
|
|
let idx = tester.len() - 1 - i;
|
|
assert_eq!(tester.swap_front_remove(idx), Some(len * 2 - 1 - i));
|
|
}
|
|
}
|
|
assert!(tester.tail < tester.cap);
|
|
assert!(tester.head < tester.cap);
|
|
assert_eq!(tester, expected);
|
|
}
|
|
}
|
|
}
|
|
test(true);
|
|
test(false);
|
|
}
|
|
|
|
#[test]
|
|
fn test_insert() {
|
|
// This test checks that every single combination of tail position, length, and
|
|
// insertion position is tested. Capacity 15 should be large enough to cover every case.
|
|
|
|
let mut tester = VecDeque::with_capacity(15);
|
|
// can't guarantee we got 15, so have to get what we got.
|
|
// 15 would be great, but we will definitely get 2^k - 1, for k >= 4, or else
|
|
// this test isn't covering what it wants to
|
|
let cap = tester.capacity();
|
|
|
|
|
|
// len is the length *after* insertion
|
|
for len in 1..cap {
|
|
// 0, 1, 2, .., len - 1
|
|
let expected = (0..).take(len).collect();
|
|
for tail_pos in 0..cap {
|
|
for to_insert in 0..len {
|
|
tester.tail = tail_pos;
|
|
tester.head = tail_pos;
|
|
for i in 0..len {
|
|
if i != to_insert {
|
|
tester.push_back(i);
|
|
}
|
|
}
|
|
tester.insert(to_insert, to_insert);
|
|
assert!(tester.tail < tester.cap);
|
|
assert!(tester.head < tester.cap);
|
|
assert_eq!(tester, expected);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
#[test]
|
|
fn test_remove() {
|
|
// This test checks that every single combination of tail position, length, and
|
|
// removal position is tested. Capacity 15 should be large enough to cover every case.
|
|
|
|
let mut tester = VecDeque::with_capacity(15);
|
|
// can't guarantee we got 15, so have to get what we got.
|
|
// 15 would be great, but we will definitely get 2^k - 1, for k >= 4, or else
|
|
// this test isn't covering what it wants to
|
|
let cap = tester.capacity();
|
|
|
|
// len is the length *after* removal
|
|
for len in 0..cap - 1 {
|
|
// 0, 1, 2, .., len - 1
|
|
let expected = (0..).take(len).collect();
|
|
for tail_pos in 0..cap {
|
|
for to_remove in 0..len + 1 {
|
|
tester.tail = tail_pos;
|
|
tester.head = tail_pos;
|
|
for i in 0..len {
|
|
if i == to_remove {
|
|
tester.push_back(1234);
|
|
}
|
|
tester.push_back(i);
|
|
}
|
|
if to_remove == len {
|
|
tester.push_back(1234);
|
|
}
|
|
tester.remove(to_remove);
|
|
assert!(tester.tail < tester.cap);
|
|
assert!(tester.head < tester.cap);
|
|
assert_eq!(tester, expected);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
#[test]
|
|
fn test_shrink_to_fit() {
|
|
// This test checks that every single combination of head and tail position,
|
|
// is tested. Capacity 15 should be large enough to cover every case.
|
|
|
|
let mut tester = VecDeque::with_capacity(15);
|
|
// can't guarantee we got 15, so have to get what we got.
|
|
// 15 would be great, but we will definitely get 2^k - 1, for k >= 4, or else
|
|
// this test isn't covering what it wants to
|
|
let cap = tester.capacity();
|
|
tester.reserve(63);
|
|
let max_cap = tester.capacity();
|
|
|
|
for len in 0..cap + 1 {
|
|
// 0, 1, 2, .., len - 1
|
|
let expected = (0..).take(len).collect();
|
|
for tail_pos in 0..max_cap + 1 {
|
|
tester.tail = tail_pos;
|
|
tester.head = tail_pos;
|
|
tester.reserve(63);
|
|
for i in 0..len {
|
|
tester.push_back(i);
|
|
}
|
|
tester.shrink_to_fit();
|
|
assert!(tester.capacity() <= cap);
|
|
assert!(tester.tail < tester.cap);
|
|
assert!(tester.head < tester.cap);
|
|
assert_eq!(tester, expected);
|
|
}
|
|
}
|
|
}
|
|
|
|
#[test]
|
|
fn test_split_off() {
|
|
// This test checks that every single combination of tail position, length, and
|
|
// split position is tested. Capacity 15 should be large enough to cover every case.
|
|
|
|
let mut tester = VecDeque::with_capacity(15);
|
|
// can't guarantee we got 15, so have to get what we got.
|
|
// 15 would be great, but we will definitely get 2^k - 1, for k >= 4, or else
|
|
// this test isn't covering what it wants to
|
|
let cap = tester.capacity();
|
|
|
|
// len is the length *before* splitting
|
|
for len in 0..cap {
|
|
// index to split at
|
|
for at in 0..len + 1 {
|
|
// 0, 1, 2, .., at - 1 (may be empty)
|
|
let expected_self = (0..).take(at).collect();
|
|
// at, at + 1, .., len - 1 (may be empty)
|
|
let expected_other = (at..).take(len - at).collect();
|
|
|
|
for tail_pos in 0..cap {
|
|
tester.tail = tail_pos;
|
|
tester.head = tail_pos;
|
|
for i in 0..len {
|
|
tester.push_back(i);
|
|
}
|
|
let result = tester.split_off(at);
|
|
assert!(tester.tail < tester.cap);
|
|
assert!(tester.head < tester.cap);
|
|
assert!(result.tail < result.cap);
|
|
assert!(result.head < result.cap);
|
|
assert_eq!(tester, expected_self);
|
|
assert_eq!(result, expected_other);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|