From 8062cfb37294082ad5825a105e47e0b7b50a7269 Mon Sep 17 00:00:00 2001 From: Charlie Fan Date: Thu, 9 Mar 2017 07:50:48 +0000 Subject: [PATCH] Implement placement-in protocol for and `VecDeque` --- src/libcollections/vec_deque.rs | 185 ++++++++++++++++++++++++---- src/libcollectionstest/lib.rs | 1 + src/libcollectionstest/vec_deque.rs | 24 +++- 3 files changed, 184 insertions(+), 26 deletions(-) diff --git a/src/libcollections/vec_deque.rs b/src/libcollections/vec_deque.rs index 8d42045ff1637..24f57c506304c 100644 --- a/src/libcollections/vec_deque.rs +++ b/src/libcollections/vec_deque.rs @@ -22,7 +22,7 @@ use core::cmp::Ordering; use core::fmt; use core::iter::{repeat, FromIterator, FusedIterator}; use core::mem; -use core::ops::{Index, IndexMut}; +use core::ops::{Index, IndexMut, Place, Placer, InPlace}; use core::ptr; use core::ptr::Shared; use core::slice; @@ -1087,14 +1087,7 @@ impl VecDeque { /// ``` #[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.grow_if_necessary(); self.tail = self.wrap_sub(self.tail, 1); let tail = self.tail; @@ -1117,14 +1110,7 @@ impl VecDeque { /// ``` #[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()); - } + self.grow_if_necessary(); let head = self.head; self.head = self.wrap_add(self.head, 1); @@ -1257,14 +1243,7 @@ impl VecDeque { #[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()); - } + self.grow_if_necessary(); // Move the least number of elements in the ring buffer and insert // the given object @@ -1762,6 +1741,69 @@ impl VecDeque { self.truncate(len - del); } } + + // This may panic or abort + #[inline] + fn grow_if_necessary(&mut self) { + if self.is_full() { + let old_cap = self.cap(); + self.buf.double(); + unsafe { + self.handle_cap_increase(old_cap); + } + debug_assert!(!self.is_full()); + } + } + + /// Returns a place for insertion at the back of the `VecDeque`. + /// + /// Using this method with placement syntax is equivalent to [`push_back`](#method.push_back), + /// but may be more efficient. + /// + /// # Examples + /// + /// ``` + /// #![feature(collection_placement)] + /// #![feature(placement_in_syntax)] + /// + /// use std::collections::VecDeque; + /// + /// let mut buf = VecDeque::new(); + /// buf.place_back() <- 3; + /// buf.place_back() <- 4; + /// assert_eq!(&buf, &[3, 4]); + /// ``` + #[unstable(feature = "collection_placement", + reason = "placement protocol is subject to change", + issue = "30172")] + pub fn place_back(&mut self) -> PlaceBack { + PlaceBack { vec_deque: self } + } + + /// Returns a place for insertion at the front of the `VecDeque`. + /// + /// Using this method with placement syntax is equivalent to [`push_front`](#method.push_front), + /// but may be more efficient. + /// + /// # Examples + /// + /// ``` + /// #![feature(collection_placement)] + /// #![feature(placement_in_syntax)] + /// + /// use std::collections::VecDeque; + /// + /// let mut buf = VecDeque::new(); + /// buf.place_front() <- 3; + /// buf.place_front() <- 4; + /// assert_eq!(&buf, &[4, 3]); + /// ``` + #[unstable(feature = "collection_placement", + reason = "placement protocol is subject to change", + issue = "30172")] + pub fn place_front(&mut self) -> PlaceFront { + PlaceFront { vec_deque: self } + } } impl VecDeque { @@ -2442,6 +2484,98 @@ impl From> for Vec { } } +/// A place for insertion at the back of a `VecDeque`. +/// +/// See [`VecDeque::place_back`](struct.VecDeque.html#method.place_back) for details. +#[must_use = "places do nothing unless written to with `<-` syntax"] +#[unstable(feature = "collection_placement", + reason = "struct name and placement protocol are subject to change", + issue = "30172")] +#[derive(Debug)] +pub struct PlaceBack<'a, T: 'a> { + vec_deque: &'a mut VecDeque, +} + +#[unstable(feature = "collection_placement", + reason = "placement protocol is subject to change", + issue = "30172")] +impl<'a, T> Placer for PlaceBack<'a, T> { + type Place = PlaceBack<'a, T>; + + fn make_place(self) -> Self { + self.vec_deque.grow_if_necessary(); + self + } +} + +#[unstable(feature = "collection_placement", + reason = "placement protocol is subject to change", + issue = "30172")] +impl<'a, T> Place for PlaceBack<'a, T> { + fn pointer(&mut self) -> *mut T { + unsafe { self.vec_deque.ptr().offset(self.vec_deque.head as isize) } + } +} + +#[unstable(feature = "collection_placement", + reason = "placement protocol is subject to change", + issue = "30172")] +impl<'a, T> InPlace for PlaceBack<'a, T> { + type Owner = &'a mut T; + + unsafe fn finalize(mut self) -> &'a mut T { + let head = self.vec_deque.head; + self.vec_deque.head = self.vec_deque.wrap_add(head, 1); + &mut *(self.vec_deque.ptr().offset(head as isize)) + } +} + +/// A place for insertion at the front of a `VecDeque`. +/// +/// See [`VecDeque::place_front`](struct.VecDeque.html#method.place_front) for details. +#[must_use = "places do nothing unless written to with `<-` syntax"] +#[unstable(feature = "collection_placement", + reason = "struct name and placement protocol are subject to change", + issue = "30172")] +#[derive(Debug)] +pub struct PlaceFront<'a, T: 'a> { + vec_deque: &'a mut VecDeque, +} + +#[unstable(feature = "collection_placement", + reason = "placement protocol is subject to change", + issue = "30172")] +impl<'a, T> Placer for PlaceFront<'a, T> { + type Place = PlaceFront<'a, T>; + + fn make_place(self) -> Self { + self.vec_deque.grow_if_necessary(); + self + } +} + +#[unstable(feature = "collection_placement", + reason = "placement protocol is subject to change", + issue = "30172")] +impl<'a, T> Place for PlaceFront<'a, T> { + fn pointer(&mut self) -> *mut T { + let tail = self.vec_deque.wrap_sub(self.vec_deque.tail, 1); + unsafe { self.vec_deque.ptr().offset(tail as isize) } + } +} + +#[unstable(feature = "collection_placement", + reason = "placement protocol is subject to change", + issue = "30172")] +impl<'a, T> InPlace for PlaceFront<'a, T> { + type Owner = &'a mut T; + + unsafe fn finalize(mut self) -> &'a mut T { + self.vec_deque.tail = self.vec_deque.wrap_sub(self.vec_deque.tail, 1); + &mut *(self.vec_deque.ptr().offset(self.vec_deque.tail as isize)) + } +} + #[cfg(test)] mod tests { use test; @@ -2797,4 +2931,5 @@ mod tests { } } } + } diff --git a/src/libcollectionstest/lib.rs b/src/libcollectionstest/lib.rs index 849d240169169..d97d9b8ab83f6 100644 --- a/src/libcollectionstest/lib.rs +++ b/src/libcollectionstest/lib.rs @@ -32,6 +32,7 @@ extern crate collections; extern crate test; extern crate std_unicode; +extern crate core; use std::hash::{Hash, Hasher}; use std::collections::hash_map::DefaultHasher; diff --git a/src/libcollectionstest/vec_deque.rs b/src/libcollectionstest/vec_deque.rs index 1541061a19842..f2935c05d4f7a 100644 --- a/src/libcollectionstest/vec_deque.rs +++ b/src/libcollectionstest/vec_deque.rs @@ -10,7 +10,7 @@ use std::collections::VecDeque; use std::fmt::Debug; -use std::collections::vec_deque::Drain; +use std::collections::vec_deque::{Drain}; use self::Taggy::*; use self::Taggypar::*; @@ -1000,3 +1000,25 @@ fn test_is_empty() { assert!(v.iter_mut().is_empty()); assert!(v.into_iter().is_empty()); } + +#[test] +fn test_placement_in() { + let mut buf: VecDeque = VecDeque::new(); + buf.place_back() <- 1; + buf.place_back() <- 2; + assert_eq!(buf, [1,2]); + + buf.place_front() <- 3; + buf.place_front() <- 4; + assert_eq!(buf, [4,3,1,2]); + + { + let ptr_head = buf.place_front() <- 5; + assert_eq!(*ptr_head, 5); + } + { + let ptr_tail = buf.place_back() <- 6; + assert_eq!(*ptr_tail, 6); + } + assert_eq!(buf, [5,4,3,1,2,6]); +}