| // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| //! VecDeque is a double-ended queue, which is implemented with the help of a |
| //! growing ring buffer. |
| //! |
| //! This queue has `O(1)` amortized inserts and removals from both ends of the |
| //! container. It also has `O(1)` indexing like a vector. The contained elements |
| //! are not required to be copyable, and the queue will be sendable if the |
| //! contained type is sendable. |
| |
| #![stable(feature = "rust1", since = "1.0.0")] |
| |
| use core::cmp::Ordering; |
| use core::fmt; |
| use core::iter::{repeat, FromIterator}; |
| use core::mem; |
| use core::ops::{Index, IndexMut}; |
| use core::ptr; |
| use core::slice; |
| |
| use core::hash::{Hash, Hasher}; |
| use core::cmp; |
| |
| use alloc::raw_vec::RawVec; |
| |
| use super::range::RangeArgument; |
| use super::vec::Vec; |
| |
| const INITIAL_CAPACITY: usize = 7; // 2^3 - 1 |
| const MINIMUM_CAPACITY: usize = 1; // 2 - 1 |
| #[cfg(target_pointer_width = "32")] |
| const MAXIMUM_ZST_CAPACITY: usize = 1 << (32 - 1); // Largest possible power of two |
| #[cfg(target_pointer_width = "64")] |
| const MAXIMUM_ZST_CAPACITY: usize = 1 << (64 - 1); // Largest possible power of two |
| |
| /// `VecDeque` is a growable ring buffer, which can be used as a double-ended |
| /// queue efficiently. |
| /// |
| /// The "default" usage of this type as a queue is to use `push_back` to add to |
| /// the queue, and `pop_front` to remove from the queue. `extend` and `append` |
| /// push onto the back in this manner, and iterating over `VecDeque` goes front |
| /// to back. |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub struct VecDeque<T> { |
| // tail and head are pointers into the buffer. Tail always points |
| // to the first element that could be read, Head always points |
| // to where data should be written. |
| // If tail == head the buffer is empty. The length of the ringbuffer |
| // is defined as the distance between the two. |
| tail: usize, |
| head: usize, |
| buf: RawVec<T>, |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T: Clone> Clone for VecDeque<T> { |
| fn clone(&self) -> VecDeque<T> { |
| self.iter().cloned().collect() |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T> Drop for VecDeque<T> { |
| #[unsafe_destructor_blind_to_params] |
| fn drop(&mut self) { |
| let (front, back) = self.as_mut_slices(); |
| unsafe { |
| // use drop for [T] |
| ptr::drop_in_place(front); |
| ptr::drop_in_place(back); |
| } |
| // RawVec handles deallocation |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T> Default for VecDeque<T> { |
| #[inline] |
| fn default() -> VecDeque<T> { |
| VecDeque::new() |
| } |
| } |
| |
| impl<T> VecDeque<T> { |
| /// Marginally more convenient |
| #[inline] |
| fn ptr(&self) -> *mut T { |
| self.buf.ptr() |
| } |
| |
| /// Marginally more convenient |
| #[inline] |
| fn cap(&self) -> usize { |
| if mem::size_of::<T>() == 0 { |
| // For zero sized types, we are always at maximum capacity |
| MAXIMUM_ZST_CAPACITY |
| } else { |
| self.buf.cap() |
| } |
| } |
| |
| /// Turn ptr into a slice |
| #[inline] |
| unsafe fn buffer_as_slice(&self) -> &[T] { |
| slice::from_raw_parts(self.ptr(), self.cap()) |
| } |
| |
| /// Turn ptr into a mut slice |
| #[inline] |
| unsafe fn buffer_as_mut_slice(&mut self) -> &mut [T] { |
| slice::from_raw_parts_mut(self.ptr(), self.cap()) |
| } |
| |
| /// Moves an element out of the buffer |
| #[inline] |
| unsafe fn buffer_read(&mut self, off: usize) -> T { |
| ptr::read(self.ptr().offset(off as isize)) |
| } |
| |
| /// Writes an element into the buffer, moving it. |
| #[inline] |
| unsafe fn buffer_write(&mut self, off: usize, value: T) { |
| ptr::write(self.ptr().offset(off as isize), value); |
| } |
| |
| /// Returns true if and only if the buffer is at capacity |
| #[inline] |
| fn is_full(&self) -> bool { |
| self.cap() - self.len() == 1 |
| } |
| |
| /// Returns the index in the underlying buffer for a given logical element |
| /// index. |
| #[inline] |
| fn wrap_index(&self, idx: usize) -> usize { |
| wrap_index(idx, self.cap()) |
| } |
| |
| /// Returns the index in the underlying buffer for a given logical element |
| /// index + addend. |
| #[inline] |
| fn wrap_add(&self, idx: usize, addend: usize) -> usize { |
| wrap_index(idx.wrapping_add(addend), self.cap()) |
| } |
| |
| /// Returns the index in the underlying buffer for a given logical element |
| /// index - subtrahend. |
| #[inline] |
| fn wrap_sub(&self, idx: usize, subtrahend: usize) -> usize { |
| wrap_index(idx.wrapping_sub(subtrahend), self.cap()) |
| } |
| |
| /// Copies a contiguous block of memory len long from src to dst |
| #[inline] |
| unsafe fn copy(&self, dst: usize, src: usize, len: usize) { |
| debug_assert!(dst + len <= self.cap(), |
| "cpy dst={} src={} len={} cap={}", |
| dst, |
| src, |
| len, |
| self.cap()); |
| debug_assert!(src + len <= self.cap(), |
| "cpy dst={} src={} len={} cap={}", |
| dst, |
| src, |
| len, |
| self.cap()); |
| ptr::copy(self.ptr().offset(src as isize), |
| self.ptr().offset(dst as isize), |
| len); |
| } |
| |
| /// Copies a contiguous block of memory len long from src to dst |
| #[inline] |
| unsafe fn copy_nonoverlapping(&self, dst: usize, src: usize, len: usize) { |
| debug_assert!(dst + len <= self.cap(), |
| "cno dst={} src={} len={} cap={}", |
| dst, |
| src, |
| len, |
| self.cap()); |
| debug_assert!(src + len <= self.cap(), |
| "cno dst={} src={} len={} cap={}", |
| dst, |
| src, |
| len, |
| self.cap()); |
| ptr::copy_nonoverlapping(self.ptr().offset(src as isize), |
| self.ptr().offset(dst as isize), |
| len); |
| } |
| |
| /// Copies a potentially wrapping block of memory len long from src to dest. |
| /// (abs(dst - src) + len) must be no larger than cap() (There must be at |
| /// most one continuous overlapping region between src and dest). |
| unsafe fn wrap_copy(&self, dst: usize, src: usize, len: usize) { |
| #[allow(dead_code)] |
| fn diff(a: usize, b: usize) -> usize { |
| if a <= b { |
| b - a |
| } else { |
| a - b |
| } |
| } |
| debug_assert!(cmp::min(diff(dst, src), self.cap() - diff(dst, src)) + len <= self.cap(), |
| "wrc dst={} src={} len={} cap={}", |
| dst, |
| src, |
| len, |
| self.cap()); |
| |
| if src == dst || len == 0 { |
| return; |
| } |
| |
| let dst_after_src = self.wrap_sub(dst, src) < len; |
| |
| let src_pre_wrap_len = self.cap() - src; |
| let dst_pre_wrap_len = self.cap() - dst; |
| let src_wraps = src_pre_wrap_len < len; |
| let dst_wraps = dst_pre_wrap_len < len; |
| |
| match (dst_after_src, src_wraps, dst_wraps) { |
| (_, false, false) => { |
| // src doesn't wrap, dst doesn't wrap |
| // |
| // S . . . |
| // 1 [_ _ A A B B C C _] |
| // 2 [_ _ A A A A B B _] |
| // D . . . |
| // |
| self.copy(dst, src, len); |
| } |
| (false, false, true) => { |
| // dst before src, src doesn't wrap, dst wraps |
| // |
| // S . . . |
| // 1 [A A B B _ _ _ C C] |
| // 2 [A A B B _ _ _ A A] |
| // 3 [B B B B _ _ _ A A] |
| // . . D . |
| // |
| self.copy(dst, src, dst_pre_wrap_len); |
| self.copy(0, src + dst_pre_wrap_len, len - dst_pre_wrap_len); |
| } |
| (true, false, true) => { |
| // src before dst, src doesn't wrap, dst wraps |
| // |
| // S . . . |
| // 1 [C C _ _ _ A A B B] |
| // 2 [B B _ _ _ A A B B] |
| // 3 [B B _ _ _ A A A A] |
| // . . D . |
| // |
| self.copy(0, src + dst_pre_wrap_len, len - dst_pre_wrap_len); |
| self.copy(dst, src, dst_pre_wrap_len); |
| } |
| (false, true, false) => { |
| // dst before src, src wraps, dst doesn't wrap |
| // |
| // . . S . |
| // 1 [C C _ _ _ A A B B] |
| // 2 [C C _ _ _ B B B B] |
| // 3 [C C _ _ _ B B C C] |
| // D . . . |
| // |
| self.copy(dst, src, src_pre_wrap_len); |
| self.copy(dst + src_pre_wrap_len, 0, len - src_pre_wrap_len); |
| } |
| (true, true, false) => { |
| // src before dst, src wraps, dst doesn't wrap |
| // |
| // . . S . |
| // 1 [A A B B _ _ _ C C] |
| // 2 [A A A A _ _ _ C C] |
| // 3 [C C A A _ _ _ C C] |
| // D . . . |
| // |
| self.copy(dst + src_pre_wrap_len, 0, len - src_pre_wrap_len); |
| self.copy(dst, src, src_pre_wrap_len); |
| } |
| (false, true, true) => { |
| // dst before src, src wraps, dst wraps |
| // |
| // . . . S . |
| // 1 [A B C D _ E F G H] |
| // 2 [A B C D _ E G H H] |
| // 3 [A B C D _ E G H A] |
| // 4 [B C C D _ E G H A] |
| // . . D . . |
| // |
| debug_assert!(dst_pre_wrap_len > src_pre_wrap_len); |
| let delta = dst_pre_wrap_len - src_pre_wrap_len; |
| self.copy(dst, src, src_pre_wrap_len); |
| self.copy(dst + src_pre_wrap_len, 0, delta); |
| self.copy(0, delta, len - dst_pre_wrap_len); |
| } |
| (true, true, true) => { |
| // src before dst, src wraps, dst wraps |
| // |
| // . . S . . |
| // 1 [A B C D _ E F G H] |
| // 2 [A A B D _ E F G H] |
| // 3 [H A B D _ E F G H] |
| // 4 [H A B D _ E F F G] |
| // . . . D . |
| // |
| debug_assert!(src_pre_wrap_len > dst_pre_wrap_len); |
| let delta = src_pre_wrap_len - dst_pre_wrap_len; |
| self.copy(delta, 0, len - src_pre_wrap_len); |
| self.copy(0, self.cap() - delta, delta); |
| self.copy(dst, src, dst_pre_wrap_len); |
| } |
| } |
| } |
| |
| /// Frobs the head and tail sections around to handle the fact that we |
| /// just reallocated. Unsafe because it trusts old_cap. |
| #[inline] |
| unsafe fn handle_cap_increase(&mut self, old_cap: usize) { |
| let new_cap = self.cap(); |
| |
| // Move the shortest contiguous section of the ring buffer |
| // T H |
| // [o o o o o o o . ] |
| // T H |
| // A [o o o o o o o . . . . . . . . . ] |
| // H T |
| // [o o . o o o o o ] |
| // T H |
| // B [. . . o o o o o o o . . . . . . ] |
| // H T |
| // [o o o o o . o o ] |
| // H T |
| // C [o o o o o . . . . . . . . . o o ] |
| |
| if self.tail <= self.head { |
| // A |
| // Nop |
| } else if self.head < old_cap - self.tail { |
| // B |
| self.copy_nonoverlapping(old_cap, 0, self.head); |
| self.head += old_cap; |
| debug_assert!(self.head > self.tail); |
| } else { |
| // C |
| let new_tail = new_cap - (old_cap - self.tail); |
| self.copy_nonoverlapping(new_tail, self.tail, old_cap - self.tail); |
| self.tail = new_tail; |
| debug_assert!(self.head < self.tail); |
| } |
| debug_assert!(self.head < self.cap()); |
| debug_assert!(self.tail < self.cap()); |
| debug_assert!(self.cap().count_ones() == 1); |
| } |
| } |
| |
| impl<T> VecDeque<T> { |
| /// Creates an empty `VecDeque`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::VecDeque; |
| /// |
| /// let vector: VecDeque<u32> = VecDeque::new(); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn new() -> VecDeque<T> { |
| VecDeque::with_capacity(INITIAL_CAPACITY) |
| } |
| |
| /// Creates an empty `VecDeque` with space for at least `n` elements. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::VecDeque; |
| /// |
| /// let vector: VecDeque<u32> = VecDeque::with_capacity(10); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn with_capacity(n: usize) -> VecDeque<T> { |
| // +1 since the ringbuffer always leaves one space empty |
| let cap = cmp::max(n + 1, MINIMUM_CAPACITY + 1).next_power_of_two(); |
| assert!(cap > n, "capacity overflow"); |
| |
| VecDeque { |
| tail: 0, |
| head: 0, |
| buf: RawVec::with_capacity(cap), |
| } |
| } |
| |
| /// Retrieves an element in the `VecDeque` by index. |
| /// |
| /// Element at index 0 is the front of the queue. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::VecDeque; |
| /// |
| /// let mut buf = VecDeque::new(); |
| /// buf.push_back(3); |
| /// buf.push_back(4); |
| /// buf.push_back(5); |
| /// assert_eq!(buf.get(1), Some(&4)); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn get(&self, index: usize) -> Option<&T> { |
| if index < self.len() { |
| let idx = self.wrap_add(self.tail, index); |
| unsafe { Some(&*self.ptr().offset(idx as isize)) } |
| } else { |
| None |
| } |
| } |
| |
| /// Retrieves an element in the `VecDeque` mutably by index. |
| /// |
| /// Element at index 0 is the front of the queue. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::VecDeque; |
| /// |
| /// let mut buf = VecDeque::new(); |
| /// buf.push_back(3); |
| /// buf.push_back(4); |
| /// buf.push_back(5); |
| /// if let Some(elem) = buf.get_mut(1) { |
| /// *elem = 7; |
| /// } |
| /// |
| /// assert_eq!(buf[1], 7); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn get_mut(&mut self, index: usize) -> Option<&mut T> { |
| if index < self.len() { |
| let idx = self.wrap_add(self.tail, index); |
| unsafe { Some(&mut *self.ptr().offset(idx as isize)) } |
| } else { |
| None |
| } |
| } |
| |
| /// Swaps elements at indices `i` and `j`. |
| /// |
| /// `i` and `j` may be equal. |
| /// |
| /// Fails if there is no element with either index. |
| /// |
| /// Element at index 0 is the front of the queue. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::VecDeque; |
| /// |
| /// let mut buf = VecDeque::new(); |
| /// buf.push_back(3); |
| /// buf.push_back(4); |
| /// buf.push_back(5); |
| /// buf.swap(0, 2); |
| /// assert_eq!(buf[0], 5); |
| /// assert_eq!(buf[2], 3); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn swap(&mut self, i: usize, j: usize) { |
| assert!(i < self.len()); |
| assert!(j < self.len()); |
| let ri = self.wrap_add(self.tail, i); |
| let rj = self.wrap_add(self.tail, j); |
| unsafe { |
| ptr::swap(self.ptr().offset(ri as isize), |
| self.ptr().offset(rj as isize)) |
| } |
| } |
| |
| /// Returns the number of elements the `VecDeque` can hold without |
| /// reallocating. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::VecDeque; |
| /// |
| /// let buf: VecDeque<i32> = VecDeque::with_capacity(10); |
| /// assert!(buf.capacity() >= 10); |
| /// ``` |
| #[inline] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn capacity(&self) -> usize { |
| self.cap() - 1 |
| } |
| |
| /// Reserves the minimum capacity for exactly `additional` more elements to be inserted in the |
| /// given `VecDeque`. Does nothing if the capacity is already sufficient. |
| /// |
| /// Note that the allocator may give the collection more space than it requests. Therefore |
| /// capacity can not be relied upon to be precisely minimal. Prefer `reserve` if future |
| /// insertions are expected. |
| /// |
| /// # Panics |
| /// |
| /// Panics if the new capacity overflows `usize`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::VecDeque; |
| /// |
| /// let mut buf: VecDeque<i32> = vec![1].into_iter().collect(); |
| /// buf.reserve_exact(10); |
| /// assert!(buf.capacity() >= 11); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn reserve_exact(&mut self, additional: usize) { |
| self.reserve(additional); |
| } |
| |
| /// Reserves capacity for at least `additional` more elements to be inserted in the given |
| /// `VecDeque`. The collection may reserve more space to avoid frequent reallocations. |
| /// |
| /// # Panics |
| /// |
| /// Panics if the new capacity overflows `usize`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::VecDeque; |
| /// |
| /// let mut buf: VecDeque<i32> = vec![1].into_iter().collect(); |
| /// buf.reserve(10); |
| /// assert!(buf.capacity() >= 11); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn reserve(&mut self, additional: usize) { |
| let old_cap = self.cap(); |
| let used_cap = self.len() + 1; |
| let new_cap = used_cap.checked_add(additional) |
| .and_then(|needed_cap| needed_cap.checked_next_power_of_two()) |
| .expect("capacity overflow"); |
| |
| if new_cap > self.capacity() { |
| self.buf.reserve_exact(used_cap, new_cap - used_cap); |
| unsafe { |
| self.handle_cap_increase(old_cap); |
| } |
| } |
| } |
| |
| /// Shrinks the capacity of the `VecDeque` as much as possible. |
| /// |
| /// It will drop down as close as possible to the length but the allocator may still inform the |
| /// `VecDeque` that there is space for a few more elements. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::VecDeque; |
| /// |
| /// let mut buf = VecDeque::with_capacity(15); |
| /// buf.extend(0..4); |
| /// assert_eq!(buf.capacity(), 15); |
| /// buf.shrink_to_fit(); |
| /// assert!(buf.capacity() >= 4); |
| /// ``` |
| #[stable(feature = "deque_extras_15", since = "1.5.0")] |
| pub fn shrink_to_fit(&mut self) { |
| // +1 since the ringbuffer always leaves one space empty |
| // len + 1 can't overflow for an existing, well-formed ringbuffer. |
| let target_cap = cmp::max(self.len() + 1, MINIMUM_CAPACITY + 1).next_power_of_two(); |
| if target_cap < self.cap() { |
| // There are three cases of interest: |
| // All elements are out of desired bounds |
| // Elements are contiguous, and head is out of desired bounds |
| // Elements are discontiguous, and tail is out of desired bounds |
| // |
| // At all other times, element positions are unaffected. |
| // |
| // Indicates that elements at the head should be moved. |
| let head_outside = self.head == 0 || self.head >= target_cap; |
| // Move elements from out of desired bounds (positions after target_cap) |
| if self.tail >= target_cap && head_outside { |
| // T H |
| // [. . . . . . . . o o o o o o o . ] |
| // T H |
| // [o o o o o o o . ] |
| unsafe { |
| self.copy_nonoverlapping(0, self.tail, self.len()); |
| } |
| self.head = self.len(); |
| self.tail = 0; |
| } else if self.tail != 0 && self.tail < target_cap && head_outside { |
| // T H |
| // [. . . o o o o o o o . . . . . . ] |
| // H T |
| // [o o . o o o o o ] |
| let len = self.wrap_sub(self.head, target_cap); |
| unsafe { |
| self.copy_nonoverlapping(0, target_cap, len); |
| } |
| self.head = len; |
| debug_assert!(self.head < self.tail); |
| } else if self.tail >= target_cap { |
| // H T |
| // [o o o o o . . . . . . . . . o o ] |
| // H T |
| // [o o o o o . o o ] |
| debug_assert!(self.wrap_sub(self.head, 1) < target_cap); |
| let len = self.cap() - self.tail; |
| let new_tail = target_cap - len; |
| unsafe { |
| self.copy_nonoverlapping(new_tail, self.tail, len); |
| } |
| self.tail = new_tail; |
| debug_assert!(self.head < self.tail); |
| } |
| |
| self.buf.shrink_to_fit(target_cap); |
| |
| debug_assert!(self.head < self.cap()); |
| debug_assert!(self.tail < self.cap()); |
| debug_assert!(self.cap().count_ones() == 1); |
| } |
| } |
| |
| /// Shortens a `VecDeque`, dropping excess elements from the back. |
| /// |
| /// If `len` is greater than the `VecDeque`'s current length, this has no |
| /// effect. |
| /// |
| /// # 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.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", |
| issue = "27788")] |
| 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`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::VecDeque; |
| /// |
| /// let mut vector: VecDeque<u32> = VecDeque::new(); |
| /// |
| /// vector.push_back(0); |
| /// vector.push_back(1); |
| /// vector.push_back(2); |
| /// |
| /// assert_eq!(vector.as_slices(), (&[0u32, 1, 2] as &[u32], &[] as &[u32])); |
| /// |
| /// vector.push_front(10); |
| /// vector.push_front(9); |
| /// |
| /// assert_eq!(vector.as_slices(), (&[9u32, 10] as &[u32], &[0u32, 1, 2] as &[u32])); |
| /// ``` |
| #[inline] |
| #[stable(feature = "deque_extras_15", since = "1.5.0")] |
| 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`. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::VecDeque; |
| /// |
| /// let mut vector: VecDeque<u32> = VecDeque::new(); |
| /// |
| /// vector.push_back(0); |
| /// vector.push_back(1); |
| /// |
| /// vector.push_front(10); |
| /// vector.push_front(9); |
| /// |
| /// vector.as_mut_slices().0[0] = 42; |
| /// vector.as_mut_slices().1[0] = 24; |
| /// assert_eq!(vector.as_slices(), (&[42u32, 10] as &[u32], &[24u32, 1] as &[u32])); |
| /// ``` |
| #[inline] |
| #[stable(feature = "deque_extras_15", since = "1.5.0")] |
| 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 |
| } |
| |
| /// Create a draining iterator that removes the specified range in the |
| /// `VecDeque` and yields the removed items. |
| /// |
| /// Note 1: The element range is removed even if the iterator is not |
| /// consumed until the end. |
| /// |
| /// Note 2: It is unspecified how many elements are removed from the deque, |
| /// if the `Drain` value is not dropped, but the borrow it holds expires |
| /// (eg. due to mem::forget). |
| /// |
| /// # Panics |
| /// |
| /// Panics if the starting point is greater than the end point or if |
| /// the end point is greater than the length of the vector. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::VecDeque; |
| /// |
| /// let mut v: VecDeque<_> = vec![1, 2, 3].into_iter().collect(); |
| /// assert_eq!(vec![3].into_iter().collect::<VecDeque<_>>(), v.drain(2..).collect()); |
| /// assert_eq!(vec![1, 2].into_iter().collect::<VecDeque<_>>(), v); |
| /// |
| /// // A full range clears all contents |
| /// v.drain(..); |
| /// assert!(v.is_empty()); |
| /// ``` |
| #[inline] |
| #[stable(feature = "drain", since = "1.6.0")] |
| pub fn drain<R>(&mut self, range: R) -> Drain<T> |
| where R: RangeArgument<usize> |
| { |
| // Memory safety |
| // |
| // When the Drain is first created, the source deque is shortened to |
| // make sure no uninitialized or moved-from elements are accessible at |
| // all if the Drain's destructor never gets to run. |
| // |
| // Drain will ptr::read out the values to remove. |
| // When finished, the remaining data will be copied back to cover the hole, |
| // and the head/tail values will be restored correctly. |
| // |
| let len = self.len(); |
| let start = *range.start().unwrap_or(&0); |
| let end = *range.end().unwrap_or(&len); |
| assert!(start <= end, "drain lower bound was too large"); |
| assert!(end <= len, "drain upper bound was too large"); |
| |
| // The deque's elements are parted into three segments: |
| // * self.tail -> drain_tail |
| // * drain_tail -> drain_head |
| // * drain_head -> self.head |
| // |
| // T = self.tail; H = self.head; t = drain_tail; h = drain_head |
| // |
| // We store drain_tail as self.head, and drain_head and self.head as |
| // after_tail and after_head respectively on the Drain. This also |
| // truncates the effective array such that if the Drain is leaked, we |
| // have forgotten about the potentially moved values after the start of |
| // the drain. |
| // |
| // T t h H |
| // [. . . o o x x o o . . .] |
| // |
| let drain_tail = self.wrap_add(self.tail, start); |
| let drain_head = self.wrap_add(self.tail, end); |
| let head = self.head; |
| |
| // "forget" about the values after the start of the drain until after |
| // the drain is complete and the Drain destructor is run. |
| self.head = drain_tail; |
| |
| Drain { |
| deque: self as *mut _, |
| after_tail: drain_head, |
| after_head: head, |
| iter: Iter { |
| tail: drain_tail, |
| head: drain_head, |
| ring: unsafe { self.buffer_as_mut_slice() }, |
| }, |
| } |
| } |
| |
| /// 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(..); |
| } |
| |
| /// Returns `true` if the `VecDeque` contains an element equal to the |
| /// given value. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// #![feature(vec_deque_contains)] |
| /// |
| /// use std::collections::VecDeque; |
| /// |
| /// let mut vector: VecDeque<u32> = VecDeque::new(); |
| /// |
| /// vector.push_back(0); |
| /// vector.push_back(1); |
| /// |
| /// assert_eq!(vector.contains(&1), true); |
| /// assert_eq!(vector.contains(&10), false); |
| /// ``` |
| #[unstable(feature = "vec_deque_contains", reason = "recently added", |
| issue = "32630")] |
| pub fn contains(&self, x: &T) -> bool |
| where T: PartialEq<T> |
| { |
| let (a, b) = self.as_slices(); |
| a.contains(x) || b.contains(x) |
| } |
| |
| /// 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, value: T) { |
| if self.is_full() { |
| let old_cap = self.cap(); |
| self.buf.double(); |
| unsafe { |
| self.handle_cap_increase(old_cap); |
| } |
| debug_assert!(!self.is_full()); |
| } |
| |
| self.tail = self.wrap_sub(self.tail, 1); |
| let tail = self.tail; |
| unsafe { |
| self.buffer_write(tail, value); |
| } |
| } |
| |
| /// 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, value: T) { |
| if self.is_full() { |
| let old_cap = self.cap(); |
| self.buf.double(); |
| unsafe { |
| self.handle_cap_increase(old_cap); |
| } |
| debug_assert!(!self.is_full()); |
| } |
| |
| let head = self.head; |
| self.head = self.wrap_add(self.head, 1); |
| unsafe { self.buffer_write(head, value) } |
| } |
| |
| /// 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. |
| /// |
| /// Element at index 0 is the front of the queue. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::VecDeque; |
| /// |
| /// let mut buf = VecDeque::new(); |
| /// assert_eq!(buf.swap_remove_back(0), None); |
| /// buf.push_back(1); |
| /// buf.push_back(2); |
| /// buf.push_back(3); |
| /// |
| /// assert_eq!(buf.swap_remove_back(0), Some(1)); |
| /// assert_eq!(buf.len(), 2); |
| /// assert_eq!(buf[0], 3); |
| /// assert_eq!(buf[1], 2); |
| /// ``` |
| #[stable(feature = "deque_extras_15", since = "1.5.0")] |
| pub fn swap_remove_back(&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. |
| /// |
| /// Element at index 0 is the front of the queue. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::VecDeque; |
| /// |
| /// let mut buf = VecDeque::new(); |
| /// assert_eq!(buf.swap_remove_front(0), None); |
| /// buf.push_back(1); |
| /// buf.push_back(2); |
| /// buf.push_back(3); |
| /// |
| /// assert_eq!(buf.swap_remove_front(2), Some(3)); |
| /// assert_eq!(buf.len(), 2); |
| /// assert_eq!(buf[0], 2); |
| /// assert_eq!(buf[1], 1); |
| /// ``` |
| #[stable(feature = "deque_extras_15", since = "1.5.0")] |
| pub fn swap_remove_front(&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 `index` 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. |
| /// |
| /// Element at index 0 is the front of the queue. |
| /// |
| /// # Panics |
| /// |
| /// Panics if `index` is greater than `VecDeque`'s length |
| /// |
| /// # Examples |
| /// ``` |
| /// 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)); |
| /// ``` |
| #[stable(feature = "deque_extras_15", since = "1.5.0")] |
| pub fn insert(&mut self, index: usize, value: T) { |
| assert!(index <= self.len(), "index out of bounds"); |
| if self.is_full() { |
| let old_cap = self.cap(); |
| self.buf.double(); |
| unsafe { |
| self.handle_cap_increase(old_cap); |
| } |
| 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, index); |
| |
| let distance_to_tail = index; |
| let distance_to_head = self.len() - index; |
| |
| let contiguous = self.is_contiguous(); |
| |
| match (contiguous, |
| distance_to_tail <= distance_to_head, |
| idx >= self.tail) { |
| (true, true, _) if index == 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 `index - 1` elements. |
| self.copy(self.tail, self.tail + 1, index - 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, index); |
| 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, index); |
| unsafe { |
| self.buffer_write(new_idx, value); |
| } |
| } |
| |
| /// Removes and returns the element at `index` 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 `index` is out of bounds. |
| /// |
| /// Element at index 0 is the front of the queue. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::collections::VecDeque; |
| /// |
| /// let mut buf = VecDeque::new(); |
| /// buf.push_back(1); |
| /// buf.push_back(2); |
| /// buf.push_back(3); |
| /// |
| /// assert_eq!(buf.remove(1), Some(2)); |
| /// assert_eq!(buf.get(1), Some(&3)); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn remove(&mut self, index: usize) -> Option<T> { |
| if self.is_empty() || self.len() <= index { |
| 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, index); |
| |
| let elem = unsafe { Some(self.buffer_read(idx)) }; |
| |
| let distance_to_tail = index; |
| let distance_to_head = self.len() - index; |
| |
| 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, index); |
| 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, index); |
| 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. |
| /// |
| /// Element at index 0 is the front of the queue. |
| /// |
| /// # Panics |
| /// |
| /// Panics if `at > len` |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// 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] |
| #[stable(feature = "split_off", since = "1.4.0")] |
| 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 |
| /// |
| /// ``` |
| /// 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] |
| #[stable(feature = "append", since = "1.4.0")] |
| 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 |
| /// |
| /// ``` |
| /// 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]); |
| /// ``` |
| #[stable(feature = "vec_deque_retain", since = "1.4.0")] |
| 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", |
| issue = "27788")] |
| 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 |
| debug_assert!(size.is_power_of_two()); |
| 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)]` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| 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> {} |
| |
| /// `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 |
| #[stable(feature = "drain", since = "1.6.0")] |
| pub struct Drain<'a, T: 'a> { |
| after_tail: usize, |
| after_head: usize, |
| iter: Iter<'a, T>, |
| deque: *mut VecDeque<T>, |
| } |
| |
| #[stable(feature = "drain", since = "1.6.0")] |
| unsafe impl<'a, T: Sync> Sync for Drain<'a, T> {} |
| #[stable(feature = "drain", since = "1.6.0")] |
| unsafe impl<'a, T: Send> Send for Drain<'a, 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() {} |
| |
| let source_deque = unsafe { &mut *self.deque }; |
| |
| // T = source_deque_tail; H = source_deque_head; t = drain_tail; h = drain_head |
| // |
| // T t h H |
| // [. . . o o x x o o . . .] |
| // |
| let orig_tail = source_deque.tail; |
| let drain_tail = source_deque.head; |
| let drain_head = self.after_tail; |
| let orig_head = self.after_head; |
| |
| let tail_len = count(orig_tail, drain_tail, source_deque.cap()); |
| let head_len = count(drain_head, orig_head, source_deque.cap()); |
| |
| // Restore the original head value |
| source_deque.head = orig_head; |
| |
| match (tail_len, head_len) { |
| (0, 0) => { |
| source_deque.head = 0; |
| source_deque.tail = 0; |
| } |
| (0, _) => { |
| source_deque.tail = drain_head; |
| } |
| (_, 0) => { |
| source_deque.head = drain_tail; |
| } |
| _ => { |
| unsafe { |
| if tail_len <= head_len { |
| source_deque.tail = source_deque.wrap_sub(drain_head, tail_len); |
| source_deque.wrap_copy(source_deque.tail, orig_tail, tail_len); |
| } else { |
| source_deque.head = source_deque.wrap_add(drain_tail, head_len); |
| source_deque.wrap_copy(drain_tail, drain_head, head_len); |
| } |
| } |
| } |
| } |
| } |
| } |
| |
| #[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.iter.next().map(|elt| unsafe { ptr::read(elt) }) |
| } |
| |
| #[inline] |
| fn size_hint(&self) -> (usize, Option<usize>) { |
| self.iter.size_hint() |
| } |
| } |
| |
| #[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.iter.next_back().map(|elt| unsafe { ptr::read(elt) }) |
| } |
| } |
| |
| #[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 { |
| if self.len() != other.len() { |
| return false; |
| } |
| let (sa, sb) = self.as_slices(); |
| let (oa, ob) = other.as_slices(); |
| if sa.len() == oa.len() { |
| sa == oa && sb == ob |
| } else if sa.len() < oa.len() { |
| // Always divisible in three sections, for example: |
| // self: [a b c|d e f] |
| // other: [0 1 2 3|4 5] |
| // front = 3, mid = 1, |
| // [a b c] == [0 1 2] && [d] == [3] && [e f] == [4 5] |
| let front = sa.len(); |
| let mid = oa.len() - front; |
| |
| let (oa_front, oa_mid) = oa.split_at(front); |
| let (sb_mid, sb_back) = sb.split_at(mid); |
| debug_assert_eq!(sa.len(), oa_front.len()); |
| debug_assert_eq!(sb_mid.len(), oa_mid.len()); |
| debug_assert_eq!(sb_back.len(), ob.len()); |
| sa == oa_front && sb_mid == oa_mid && sb_back == ob |
| } else { |
| let front = oa.len(); |
| let mid = sa.len() - front; |
| |
| let (sa_front, sa_mid) = sa.split_at(front); |
| let (ob_mid, ob_back) = ob.split_at(mid); |
| debug_assert_eq!(sa_front.len(), oa.len()); |
| debug_assert_eq!(sa_mid.len(), ob_mid.len()); |
| debug_assert_eq!(sb.len(), ob_back.len()); |
| sa_front == oa && sa_mid == ob_mid && sb == ob_back |
| } |
| } |
| } |
| |
| #[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> { |
| self.iter().partial_cmp(other.iter()) |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<A: Ord> Ord for VecDeque<A> { |
| #[inline] |
| fn cmp(&self, other: &VecDeque<A>) -> Ordering { |
| self.iter().cmp(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); |
| let (a, b) = self.as_slices(); |
| Hash::hash_slice(a, state); |
| Hash::hash_slice(b, state); |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<A> Index<usize> for VecDeque<A> { |
| type Output = A; |
| |
| #[inline] |
| fn index(&self, index: usize) -> &A { |
| self.get(index).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, index: usize) -> &mut A { |
| self.get_mut(index).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>>(iter: T) -> VecDeque<A> { |
| let iterator = iter.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 { |
| f.debug_list().entries(self).finish() |
| } |
| } |
| |
| #[stable(feature = "vecdeque_vec_conversions", since = "1.10.0")] |
| impl<T> From<Vec<T>> for VecDeque<T> { |
| fn from(mut other: Vec<T>) -> Self { |
| unsafe { |
| let other_buf = other.as_mut_ptr(); |
| let mut buf = RawVec::from_raw_parts(other_buf, other.capacity()); |
| let len = other.len(); |
| mem::forget(other); |
| |
| // We need to extend the buf if it's not a power of two, too small |
| // or doesn't have at least one free space |
| if !buf.cap().is_power_of_two() |
| || (buf.cap() < (MINIMUM_CAPACITY + 1)) |
| || (buf.cap() == len) |
| { |
| let cap = cmp::max(buf.cap() + 1, MINIMUM_CAPACITY + 1).next_power_of_two(); |
| buf.reserve_exact(len, cap - len); |
| } |
| |
| VecDeque { |
| tail: 0, |
| head: len, |
| buf: buf |
| } |
| } |
| } |
| } |
| |
| #[stable(feature = "vecdeque_vec_conversions", since = "1.10.0")] |
| impl<T> From<VecDeque<T>> for Vec<T> { |
| fn from(other: VecDeque<T>) -> Self { |
| unsafe { |
| let buf = other.buf.ptr(); |
| let len = other.len(); |
| let tail = other.tail; |
| let head = other.head; |
| let cap = other.cap(); |
| |
| // Need to move the ring to the front of the buffer, as vec will expect this. |
| if other.is_contiguous() { |
| ptr::copy(buf.offset(tail as isize), buf, len); |
| } else { |
| if (tail - head) >= cmp::min((cap - tail), head) { |
| // There is enough free space in the centre for the shortest block so we can |
| // do this in at most three copy moves. |
| if (cap - tail) > head { |
| // right hand block is the long one; move that enough for the left |
| ptr::copy( |
| buf.offset(tail as isize), |
| buf.offset((tail - head) as isize), |
| cap - tail); |
| // copy left in the end |
| ptr::copy(buf, buf.offset((cap - head) as isize), head); |
| // shift the new thing to the start |
| ptr::copy(buf.offset((tail-head) as isize), buf, len); |
| } else { |
| // left hand block is the long one, we can do it in two! |
| ptr::copy(buf, buf.offset((cap-tail) as isize), head); |
| ptr::copy(buf.offset(tail as isize), buf, cap-tail); |
| } |
| } else { |
| // Need to use N swaps to move the ring |
| // We can use the space at the end of the ring as a temp store |
| |
| let mut left_edge: usize = 0; |
| let mut right_edge: usize = tail; |
| |
| // The general problem looks like this |
| // GHIJKLM...ABCDEF - before any swaps |
| // ABCDEFM...GHIJKL - after 1 pass of swaps |
| // ABCDEFGHIJM...KL - swap until the left edge reaches the temp store |
| // - then restart the algorithm with a new (smaller) store |
| // Sometimes the temp store is reached when the right edge is at the end |
| // of the buffer - this means we've hit the right order with fewer swaps! |
| // E.g |
| // EF..ABCD |
| // ABCDEF.. - after four only swaps we've finished |
| |
| while left_edge < len && right_edge != cap { |
| let mut right_offset = 0; |
| for i in left_edge..right_edge { |
| right_offset = (i - left_edge) % (cap - right_edge); |
| let src: isize = (right_edge + right_offset) as isize; |
| ptr::swap(buf.offset(i as isize), buf.offset(src)); |
| } |
| let n_ops = right_edge - left_edge; |
| left_edge += n_ops; |
| right_edge += right_offset + 1; |
| |
| } |
| } |
| |
| } |
| let out = Vec::from_raw_parts(buf, len, cap); |
| mem::forget(other); |
| out |
| } |
| } |
| } |
| |
| #[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_remove_back(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_remove_front(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_drain() { |
| let mut tester: VecDeque<usize> = VecDeque::with_capacity(7); |
| |
| let cap = tester.capacity(); |
| for len in 0..cap + 1 { |
| for tail in 0..cap + 1 { |
| for drain_start in 0..len + 1 { |
| for drain_end in drain_start..len + 1 { |
| tester.tail = tail; |
| tester.head = tail; |
| for i in 0..len { |
| tester.push_back(i); |
| } |
| |
| // Check that we drain the correct values |
| let drained: VecDeque<_> = tester.drain(drain_start..drain_end).collect(); |
| let drained_expected: VecDeque<_> = (drain_start..drain_end).collect(); |
| assert_eq!(drained, drained_expected); |
| |
| // We shouldn't have changed the capacity or made the |
| // head or tail out of bounds |
| assert_eq!(tester.capacity(), cap); |
| assert!(tester.tail < tester.cap()); |
| assert!(tester.head < tester.cap()); |
| |
| // We should see the correct values in the VecDeque |
| let expected: VecDeque<_> = (0..drain_start) |
| .chain(drain_end..len) |
| .collect(); |
| assert_eq!(expected, tester); |
| } |
| } |
| } |
| } |
| } |
| |
| #[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); |
| } |
| } |
| } |
| } |
| |
| #[test] |
| fn test_from_vec() { |
| use super::super::vec::Vec; |
| for cap in 0..35 { |
| for len in 0..cap + 1 { |
| let mut vec = Vec::with_capacity(cap); |
| vec.extend(0..len); |
| |
| let vd = VecDeque::from(vec.clone()); |
| assert!(vd.cap().is_power_of_two()); |
| assert_eq!(vd.len(), vec.len()); |
| assert!(vd.into_iter().eq(vec)); |
| } |
| } |
| } |
| |
| #[test] |
| fn test_vec_from_vecdeque() { |
| use super::super::vec::Vec; |
| |
| fn create_vec_and_test_convert(cap: usize, offset: usize, len: usize) { |
| let mut vd = VecDeque::with_capacity(cap); |
| for _ in 0..offset { |
| vd.push_back(0); |
| vd.pop_front(); |
| } |
| vd.extend(0..len); |
| |
| let vec: Vec<_> = Vec::from(vd.clone()); |
| assert_eq!(vec.len(), vd.len()); |
| assert!(vec.into_iter().eq(vd)); |
| } |
| |
| for cap_pwr in 0..7 { |
| // Make capacity as a (2^x)-1, so that the ring size is 2^x |
| let cap = (2i32.pow(cap_pwr) - 1) as usize; |
| |
| // In these cases there is enough free space to solve it with copies |
| for len in 0..((cap+1)/2) { |
| // Test contiguous cases |
| for offset in 0..(cap-len) { |
| create_vec_and_test_convert(cap, offset, len) |
| } |
| |
| // Test cases where block at end of buffer is bigger than block at start |
| for offset in (cap-len)..(cap-(len/2)) { |
| create_vec_and_test_convert(cap, offset, len) |
| } |
| |
| // Test cases where block at start of buffer is bigger than block at end |
| for offset in (cap-(len/2))..cap { |
| create_vec_and_test_convert(cap, offset, len) |
| } |
| } |
| |
| // Now there's not (necessarily) space to straighten the ring with simple copies, |
| // the ring will use swapping when: |
| // (cap + 1 - offset) > (cap + 1 - len) && (len - (cap + 1 - offset)) > (cap + 1 - len)) |
| // right block size > free space && left block size > free space |
| for len in ((cap+1)/2)..cap { |
| // Test contiguous cases |
| for offset in 0..(cap-len) { |
| create_vec_and_test_convert(cap, offset, len) |
| } |
| |
| // Test cases where block at end of buffer is bigger than block at start |
| for offset in (cap-len)..(cap-(len/2)) { |
| create_vec_and_test_convert(cap, offset, len) |
| } |
| |
| // Test cases where block at start of buffer is bigger than block at end |
| for offset in (cap-(len/2))..cap { |
| create_vec_and_test_convert(cap, offset, len) |
| } |
| } |
| } |
| } |
| } |