libcollections

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+// Copyright 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.
+
+//! A contiguous growable array type with heap-allocated contents, written
+//! `Vec<T>` but pronounced 'vector.'
+//!
+//! Vectors have `O(1)` indexing, amortized `O(1)` push (to the end) and
+//! `O(1)` pop (from the end).
+//!
+//! # Examples
+//!
+//! You can explicitly create a `Vec<T>` with `new()`:
+//!
+//! ```
+//! let v: Vec<i32> = Vec::new();
+//! ```
+//!
+//! ...or by using the `vec!` macro:
+//!
+//! ```
+//! let v: Vec<i32> = vec![];
+//!
+//! let v = vec![1, 2, 3, 4, 5];
+//!
+//! let v = vec![0; 10]; // ten zeroes
+//! ```
+//!
+//! You can `push` values onto the end of a vector (which will grow the vector
+//! as needed):
+//!
+//! ```
+//! let mut v = vec![1, 2];
+//!
+//! v.push(3);
+//! ```
+//!
+//! Popping values works in much the same way:
+//!
+//! ```
+//! let mut v = vec![1, 2];
+//!
+//! let two = v.pop();
+//! ```
+//!
+//! Vectors also support indexing (through the `Index` and `IndexMut` traits):
+//!
+//! ```
+//! let mut v = vec![1, 2, 3];
+//! let three = v[2];
+//! v[1] = v[1] + 5;
+//! ```
+
+#![stable(feature = "rust1", since = "1.0.0")]
+
+use alloc::boxed::Box;
+use alloc::heap::EMPTY;
+use alloc::raw_vec::RawVec;
+use borrow::ToOwned;
+use borrow::Cow;
+use core::cmp::Ordering;
+use core::fmt;
+use core::hash::{self, Hash};
+use core::intrinsics::{arith_offset, assume};
+use core::iter::FromIterator;
+use core::mem;
+use core::ops::{Index, IndexMut};
+use core::ops;
+use core::ptr;
+use core::slice;
+
+use super::range::RangeArgument;
+
+/// A contiguous growable array type, written `Vec<T>` but pronounced 'vector.'
+///
+/// # Examples
+///
+/// ```
+/// let mut vec = Vec::new();
+/// vec.push(1);
+/// vec.push(2);
+///
+/// assert_eq!(vec.len(), 2);
+/// assert_eq!(vec[0], 1);
+///
+/// assert_eq!(vec.pop(), Some(2));
+/// assert_eq!(vec.len(), 1);
+///
+/// vec[0] = 7;
+/// assert_eq!(vec[0], 7);
+///
+/// vec.extend([1, 2, 3].iter().cloned());
+///
+/// for x in &vec {
+///     println!("{}", x);
+/// }
+/// assert_eq!(vec, [7, 1, 2, 3]);
+/// ```
+///
+/// The `vec!` macro is provided to make initialization more convenient:
+///
+/// ```
+/// let mut vec = vec![1, 2, 3];
+/// vec.push(4);
+/// assert_eq!(vec, [1, 2, 3, 4]);
+/// ```
+///
+/// It can also initialize each element of a `Vec<T>` with a given value:
+///
+/// ```
+/// let vec = vec![0; 5];
+/// assert_eq!(vec, [0, 0, 0, 0, 0]);
+/// ```
+///
+/// Use a `Vec<T>` as an efficient stack:
+///
+/// ```
+/// let mut stack = Vec::new();
+///
+/// stack.push(1);
+/// stack.push(2);
+/// stack.push(3);
+///
+/// while let Some(top) = stack.pop() {
+///     // Prints 3, 2, 1
+///     println!("{}", top);
+/// }
+/// ```
+///
+/// # Indexing
+///
+/// The Vec type allows to access values by index, because it implements the
+/// `Index` trait. An example will be more explicit:
+///
+/// ```
+/// let v = vec!(0, 2, 4, 6);
+/// println!("{}", v[1]); // it will display '2'
+/// ```
+///
+/// However be careful: if you try to access an index which isn't in the Vec,
+/// your software will panic! You cannot do this:
+///
+/// ```ignore
+/// let v = vec!(0, 2, 4, 6);
+/// println!("{}", v[6]); // it will panic!
+/// ```
+///
+/// In conclusion: always check if the index you want to get really exists
+/// before doing it.
+///
+/// # Slicing
+///
+/// A Vec can be mutable. Slices, on the other hand, are read-only objects.
+/// To get a slice, use "&". Example:
+///
+/// ```
+/// fn read_slice(slice: &[usize]) {
+///     // ...
+/// }
+///
+/// let v = vec!(0, 1);
+/// read_slice(&v);
+///
+/// // ... and that's all!
+/// // you can also do it like this:
+/// let x : &[usize] = &v;
+/// ```
+///
+/// In Rust, it's more common to pass slices as arguments rather than vectors
+/// when you just want to provide a read access. The same goes for String and
+/// &str.
+///
+/// # Capacity and reallocation
+///
+/// The capacity of a vector is the amount of space allocated for any future
+/// elements that will be added onto the vector. This is not to be confused with
+/// the *length* of a vector, which specifies the number of actual elements
+/// within the vector. If a vector's length exceeds its capacity, its capacity
+/// will automatically be increased, but its elements will have to be
+/// reallocated.
+///
+/// For example, a vector with capacity 10 and length 0 would be an empty vector
+/// with space for 10 more elements. Pushing 10 or fewer elements onto the
+/// vector will not change its capacity or cause reallocation to occur. However,
+/// if the vector's length is increased to 11, it will have to reallocate, which
+/// can be slow. For this reason, it is recommended to use `Vec::with_capacity`
+/// whenever possible to specify how big the vector is expected to get.
+///
+/// # Guarantees
+///
+/// Due to its incredibly fundamental nature, Vec makes a lot of guarantees
+/// about its design. This ensures that it's as low-overhead as possible in
+/// the general case, and can be correctly manipulated in primitive ways
+/// by unsafe code. Note that these guarantees refer to an unqualified `Vec<T>`.
+/// If additional type parameters are added (e.g. to support custom allocators),
+/// overriding their defaults may change the behavior.
+///
+/// Most fundamentally, Vec is and always will be a (pointer, capacity, length)
+/// triplet. No more, no less. The order of these fields is completely
+/// unspecified, and you should use the appropriate methods to modify these.
+/// The pointer will never be null, so this type is null-pointer-optimized.
+///
+/// However, the pointer may not actually point to allocated memory. In particular,
+/// if you construct a Vec with capacity 0 via `Vec::new()`, `vec![]`,
+/// `Vec::with_capacity(0)`, or by calling `shrink_to_fit()` on an empty Vec, it
+/// will not allocate memory. Similarly, if you store zero-sized types inside
+/// a Vec, it will not allocate space for them. *Note that in this case the
+/// Vec may not report a `capacity()` of 0*. Vec will allocate if and only
+/// if `mem::size_of::<T>() * capacity() > 0`. In general, Vec's allocation
+/// details are subtle enough that it is strongly recommended that you only
+/// free memory allocated by a Vec by creating a new Vec and dropping it.
+///
+/// If a Vec *has* allocated memory, then the memory it points to is on the heap
+/// (as defined by the allocator Rust is configured to use by default), and its
+/// pointer points to `len()` initialized elements in order (what you would see
+/// if you coerced it to a slice), followed by `capacity() - len()` logically
+/// uninitialized elements.
+///
+/// Vec will never perform a "small optimization" where elements are actually
+/// stored on the stack for two reasons:
+///
+/// * It would make it more difficult for unsafe code to correctly manipulate
+///   a Vec. The contents of a Vec wouldn't have a stable address if it were
+///   only moved, and it would be more difficult to determine if a Vec had
+///   actually allocated memory.
+///
+/// * It would penalize the general case, incurring an additional branch
+///   on every access.
+///
+/// Vec will never automatically shrink itself, even if completely empty. This
+/// ensures no unnecessary allocations or deallocations occur. Emptying a Vec
+/// and then filling it back up to the same `len()` should incur no calls to
+/// the allocator. If you wish to free up unused memory, use `shrink_to_fit`.
+///
+/// `push` and `insert` will never (re)allocate if the reported capacity is
+/// sufficient. `push` and `insert` *will* (re)allocate if `len() == capacity()`.
+/// That is, the reported capacity is completely accurate, and can be relied on.
+/// It can even be used to manually free the memory allocated by a Vec if
+/// desired. Bulk insertion methods *may* reallocate, even when not necessary.
+///
+/// Vec does not guarantee any particular growth strategy when reallocating
+/// when full, nor when `reserve` is called. The current strategy is basic
+/// and it may prove desirable to use a non-constant growth factor. Whatever
+/// strategy is used will of course guarantee `O(1)` amortized `push`.
+///
+/// `vec![x; n]`, `vec![a, b, c, d]`, and `Vec::with_capacity(n)`, will all
+/// produce a Vec with exactly the requested capacity. If `len() == capacity()`,
+/// (as is the case for the `vec!` macro), then a `Vec<T>` can be converted
+/// to and from a `Box<[T]>` without reallocating or moving the elements.
+///
+/// Vec will not specifically overwrite any data that is removed from it,
+/// but also won't specifically preserve it. Its uninitialized memory is
+/// scratch space that it may use however it wants. It will generally just do
+/// whatever is most efficient or otherwise easy to implement. Do not rely on
+/// removed data to be erased for security purposes. Even if you drop a Vec, its
+/// buffer may simply be reused by another Vec. Even if you zero a Vec's memory
+/// first, that may not actually happen because the optimizer does not consider
+/// this a side-effect that must be preserved.
+///
+/// Vec does not currently guarantee the order in which elements are dropped
+/// (the order has changed in the past, and may change again).
+///
+#[unsafe_no_drop_flag]
+#[stable(feature = "rust1", since = "1.0.0")]
+pub struct Vec<T> {
+    buf: RawVec<T>,
+    len: usize,
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Inherent methods
+////////////////////////////////////////////////////////////////////////////////
+
+impl<T> Vec<T> {
+    /// Constructs a new, empty `Vec<T>`.
+    ///
+    /// The vector will not allocate until elements are pushed onto it.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # #![allow(unused_mut)]
+    /// let mut vec: Vec<i32> = Vec::new();
+    /// ```
+    #[inline]
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub fn new() -> Vec<T> {
+        Vec {
+            buf: RawVec::new(),
+            len: 0,
+        }
+    }
+
+    /// Constructs a new, empty `Vec<T>` with the specified capacity.
+    ///
+    /// The vector will be able to hold exactly `capacity` elements without
+    /// reallocating. If `capacity` is 0, the vector will not allocate.
+    ///
+    /// It is important to note that this function does not specify the *length*
+    /// of the returned vector, but only the *capacity*. (For an explanation of
+    /// the difference between length and capacity, see the main `Vec<T>` docs
+    /// above, 'Capacity and reallocation'.)
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut vec = Vec::with_capacity(10);
+    ///
+    /// // The vector contains no items, even though it has capacity for more
+    /// assert_eq!(vec.len(), 0);
+    ///
+    /// // These are all done without reallocating...
+    /// for i in 0..10 {
+    ///     vec.push(i);
+    /// }
+    ///
+    /// // ...but this may make the vector reallocate
+    /// vec.push(11);
+    /// ```
+    #[inline]
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub fn with_capacity(capacity: usize) -> Vec<T> {
+        Vec {
+            buf: RawVec::with_capacity(capacity),
+            len: 0,
+        }
+    }
+
+    /// Creates a `Vec<T>` directly from the raw components of another vector.
+    ///
+    /// # Safety
+    ///
+    /// This is highly unsafe, due to the number of invariants that aren't
+    /// checked:
+    ///
+    /// * `ptr` needs to have been previously allocated via `String`/`Vec<T>`
+    ///   (at least, it's highly likely to be incorrect if it wasn't).
+    /// * `length` needs to be the length that less than or equal to `capacity`.
+    /// * `capacity` needs to be the capacity that the pointer was allocated with.
+    ///
+    /// Violating these may cause problems like corrupting the allocator's
+    /// internal datastructures.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::ptr;
+    /// use std::mem;
+    ///
+    /// fn main() {
+    ///     let mut v = vec![1, 2, 3];
+    ///
+    ///     // Pull out the various important pieces of information about `v`
+    ///     let p = v.as_mut_ptr();
+    ///     let len = v.len();
+    ///     let cap = v.capacity();
+    ///
+    ///     unsafe {
+    ///         // Cast `v` into the void: no destructor run, so we are in
+    ///         // complete control of the allocation to which `p` points.
+    ///         mem::forget(v);
+    ///
+    ///         // Overwrite memory with 4, 5, 6
+    ///         for i in 0..len as isize {
+    ///             ptr::write(p.offset(i), 4 + i);
+    ///         }
+    ///
+    ///         // Put everything back together into a Vec
+    ///         let rebuilt = Vec::from_raw_parts(p, len, cap);
+    ///         assert_eq!(rebuilt, [4, 5, 6]);
+    ///     }
+    /// }
+    /// ```
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub unsafe fn from_raw_parts(ptr: *mut T, length: usize, capacity: usize) -> Vec<T> {
+        Vec {
+            buf: RawVec::from_raw_parts(ptr, capacity),
+            len: length,
+        }
+    }
+
+    /// Returns the number of elements the vector can hold without
+    /// reallocating.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let vec: Vec<i32> = Vec::with_capacity(10);
+    /// assert_eq!(vec.capacity(), 10);
+    /// ```
+    #[inline]
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub fn capacity(&self) -> usize {
+        self.buf.cap()
+    }
+
+    /// Reserves capacity for at least `additional` more elements to be inserted
+    /// in the given `Vec<T>`. The collection may reserve more space to avoid
+    /// frequent reallocations.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the new capacity overflows `usize`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut vec = vec![1];
+    /// vec.reserve(10);
+    /// assert!(vec.capacity() >= 11);
+    /// ```
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub fn reserve(&mut self, additional: usize) {
+        self.buf.reserve(self.len, additional);
+    }
+
+    /// Reserves the minimum capacity for exactly `additional` more elements to
+    /// be inserted in the given `Vec<T>`. 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
+    ///
+    /// ```
+    /// let mut vec = vec![1];
+    /// vec.reserve_exact(10);
+    /// assert!(vec.capacity() >= 11);
+    /// ```
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub fn reserve_exact(&mut self, additional: usize) {
+        self.buf.reserve_exact(self.len, additional);
+    }
+
+    /// Shrinks the capacity of the vector as much as possible.
+    ///
+    /// It will drop down as close as possible to the length but the allocator
+    /// may still inform the vector that there is space for a few more elements.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut vec = Vec::with_capacity(10);
+    /// vec.extend([1, 2, 3].iter().cloned());
+    /// assert_eq!(vec.capacity(), 10);
+    /// vec.shrink_to_fit();
+    /// assert!(vec.capacity() >= 3);
+    /// ```
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub fn shrink_to_fit(&mut self) {
+        self.buf.shrink_to_fit(self.len);
+    }
+
+    /// Converts the vector into Box<[T]>.
+    ///
+    /// Note that this will drop any excess capacity. Calling this and
+    /// converting back to a vector with `into_vec()` is equivalent to calling
+    /// `shrink_to_fit()`.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub fn into_boxed_slice(mut self) -> Box<[T]> {
+        unsafe {
+            self.shrink_to_fit();
+            let buf = ptr::read(&self.buf);
+            mem::forget(self);
+            buf.into_box()
+        }
+    }
+
+    /// Shorten a vector to be `len` elements long, dropping excess elements.
+    ///
+    /// If `len` is greater than the vector's current length, this has no
+    /// effect.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut vec = vec![1, 2, 3, 4, 5];
+    /// vec.truncate(2);
+    /// assert_eq!(vec, [1, 2]);
+    /// ```
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub fn truncate(&mut self, len: usize) {
+        unsafe {
+            // drop any extra elements
+            while len < self.len {
+                // decrement len before the drop_in_place(), so a panic on Drop
+                // doesn't re-drop the just-failed value.
+                self.len -= 1;
+                let len = self.len;
+                ptr::drop_in_place(self.get_unchecked_mut(len));
+            }
+        }
+    }
+
+    /// Extracts a slice containing the entire vector.
+    ///
+    /// Equivalent to `&s[..]`.
+    #[inline]
+    #[stable(feature = "vec_as_slice", since = "1.7.0")]
+    pub fn as_slice(&self) -> &[T] {
+        self
+    }
+
+    /// Extracts a mutable slice of the entire vector.
+    ///
+    /// Equivalent to `&mut s[..]`.
+    #[inline]
+    #[stable(feature = "vec_as_slice", since = "1.7.0")]
+    pub fn as_mut_slice(&mut self) -> &mut [T] {
+        &mut self[..]
+    }
+
+    /// Sets the length of a vector.
+    ///
+    /// This will explicitly set the size of the vector, without actually
+    /// modifying its buffers, so it is up to the caller to ensure that the
+    /// vector is actually the specified size.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut v = vec![1, 2, 3, 4];
+    /// unsafe {
+    ///     v.set_len(1);
+    /// }
+    /// ```
+    #[inline]
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub unsafe fn set_len(&mut self, len: usize) {
+        self.len = len;
+    }
+
+    /// Removes an element from anywhere in the vector and return it, replacing
+    /// it with the last element.
+    ///
+    /// This does not preserve ordering, but is O(1).
+    ///
+    /// # Panics
+    ///
+    /// Panics if `index` is out of bounds.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut v = vec!["foo", "bar", "baz", "qux"];
+    ///
+    /// assert_eq!(v.swap_remove(1), "bar");
+    /// assert_eq!(v, ["foo", "qux", "baz"]);
+    ///
+    /// assert_eq!(v.swap_remove(0), "foo");
+    /// assert_eq!(v, ["baz", "qux"]);
+    /// ```
+    #[inline]
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub fn swap_remove(&mut self, index: usize) -> T {
+        let length = self.len();
+        self.swap(index, length - 1);
+        self.pop().unwrap()
+    }
+
+    /// Inserts an element at position `index` within the vector, shifting all
+    /// elements after it to the right.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `index` is greater than the vector's length.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut vec = vec![1, 2, 3];
+    /// vec.insert(1, 4);
+    /// assert_eq!(vec, [1, 4, 2, 3]);
+    /// vec.insert(4, 5);
+    /// assert_eq!(vec, [1, 4, 2, 3, 5]);
+    /// ```
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub fn insert(&mut self, index: usize, element: T) {
+        let len = self.len();
+        assert!(index <= len);
+
+        // space for the new element
+        if len == self.buf.cap() {
+            self.buf.double();
+        }
+
+        unsafe {
+            // infallible
+            // The spot to put the new value
+            {
+                let p = self.as_mut_ptr().offset(index as isize);
+                // Shift everything over to make space. (Duplicating the
+                // `index`th element into two consecutive places.)
+                ptr::copy(p, p.offset(1), len - index);
+                // Write it in, overwriting the first copy of the `index`th
+                // element.
+                ptr::write(p, element);
+            }
+            self.set_len(len + 1);
+        }
+    }
+
+    /// Removes and returns the element at position `index` within the vector,
+    /// shifting all elements after it to the left.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `index` is out of bounds.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut v = vec![1, 2, 3];
+    /// assert_eq!(v.remove(1), 2);
+    /// assert_eq!(v, [1, 3]);
+    /// ```
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub fn remove(&mut self, index: usize) -> T {
+        let len = self.len();
+        assert!(index < len);
+        unsafe {
+            // infallible
+            let ret;
+            {
+                // the place we are taking from.
+                let ptr = self.as_mut_ptr().offset(index as isize);
+                // copy it out, unsafely having a copy of the value on
+                // the stack and in the vector at the same time.
+                ret = ptr::read(ptr);
+
+                // Shift everything down to fill in that spot.
+                ptr::copy(ptr.offset(1), ptr, len - index - 1);
+            }
+            self.set_len(len - 1);
+            ret
+        }
+    }
+
+    /// 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
+    ///
+    /// ```
+    /// let mut vec = vec![1, 2, 3, 4];
+    /// vec.retain(|&x| x%2 == 0);
+    /// assert_eq!(vec, [2, 4]);
+    /// ```
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub fn retain<F>(&mut self, mut f: F)
+        where F: FnMut(&T) -> bool
+    {
+        let len = self.len();
+        let mut del = 0;
+        {
+            let v = &mut **self;
+
+            for i in 0..len {
+                if !f(&v[i]) {
+                    del += 1;
+                } else if del > 0 {
+                    v.swap(i - del, i);
+                }
+            }
+        }
+        if del > 0 {
+            self.truncate(len - del);
+        }
+    }
+
+    /// Appends an element to the back of a collection.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the number of elements in the vector overflows a `usize`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut vec = vec![1, 2];
+    /// vec.push(3);
+    /// assert_eq!(vec, [1, 2, 3]);
+    /// ```
+    #[inline]
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub fn push(&mut self, value: T) {
+        // This will panic or abort if we would allocate > isize::MAX bytes
+        // or if the length increment would overflow for zero-sized types.
+        if self.len == self.buf.cap() {
+            self.buf.double();
+        }
+        unsafe {
+            let end = self.as_mut_ptr().offset(self.len as isize);
+            ptr::write(end, value);
+            self.len += 1;
+        }
+    }
+
+    /// Removes the last element from a vector and returns it, or `None` if it
+    /// is empty.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut vec = vec![1, 2, 3];
+    /// assert_eq!(vec.pop(), Some(3));
+    /// assert_eq!(vec, [1, 2]);
+    /// ```
+    #[inline]
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub fn pop(&mut self) -> Option<T> {
+        if self.len == 0 {
+            None
+        } else {
+            unsafe {
+                self.len -= 1;
+                Some(ptr::read(self.get_unchecked(self.len())))
+            }
+        }
+    }
+
+    /// Moves all the elements of `other` into `Self`, leaving `other` empty.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the number of elements in the vector overflows a `usize`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut vec = vec![1, 2, 3];
+    /// let mut vec2 = vec![4, 5, 6];
+    /// vec.append(&mut vec2);
+    /// assert_eq!(vec, [1, 2, 3, 4, 5, 6]);
+    /// assert_eq!(vec2, []);
+    /// ```
+    #[inline]
+    #[stable(feature = "append", since = "1.4.0")]
+    pub fn append(&mut self, other: &mut Self) {
+        self.reserve(other.len());
+        let len = self.len();
+        unsafe {
+            ptr::copy_nonoverlapping(other.as_ptr(), self.get_unchecked_mut(len), other.len());
+        }
+
+        self.len += other.len();
+        unsafe {
+            other.set_len(0);
+        }
+    }
+
+    /// Create a draining iterator that removes the specified range in the vector
+    /// 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 vector,
+    /// if the `Drain` value is leaked.
+    ///
+    /// # 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
+    ///
+    /// ```
+    /// let mut v = vec![1, 2, 3];
+    /// let u: Vec<_> = v.drain(1..).collect();
+    /// assert_eq!(v, &[1]);
+    /// assert_eq!(u, &[2, 3]);
+    ///
+    /// // A full range clears the vector
+    /// v.drain(..);
+    /// assert_eq!(v, &[]);
+    /// ```
+    #[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, it shortens the length of
+        // the source vector to make sure no uninitalized 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, remaining tail of the vec is copied back to cover
+        // the hole, and the vector length is restored to the new length.
+        //
+        let len = self.len();
+        let start = *range.start().unwrap_or(&0);
+        let end = *range.end().unwrap_or(&len);
+        assert!(start <= end);
+        assert!(end <= len);
+
+        unsafe {
+            // set self.vec length's to start, to be safe in case Drain is leaked
+            self.set_len(start);
+            // Use the borrow in the IterMut to indicate borrowing behavior of the
+            // whole Drain iterator (like &mut T).
+            let range_slice = slice::from_raw_parts_mut(self.as_mut_ptr().offset(start as isize),
+                                                        end - start);
+            Drain {
+                tail_start: end,
+                tail_len: len - end,
+                iter: range_slice.iter_mut(),
+                vec: self as *mut _,
+            }
+        }
+    }
+
+    /// Clears the vector, removing all values.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut v = vec![1, 2, 3];
+    ///
+    /// v.clear();
+    ///
+    /// assert!(v.is_empty());
+    /// ```
+    #[inline]
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub fn clear(&mut self) {
+        self.truncate(0)
+    }
+
+    /// Returns the number of elements in the vector.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let a = vec![1, 2, 3];
+    /// assert_eq!(a.len(), 3);
+    /// ```
+    #[inline]
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub fn len(&self) -> usize {
+        self.len
+    }
+
+    /// Returns `true` if the vector contains no elements.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut v = Vec::new();
+    /// assert!(v.is_empty());
+    ///
+    /// v.push(1);
+    /// assert!(!v.is_empty());
+    /// ```
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
+
+    /// 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
+    ///
+    /// ```
+    /// let mut vec = vec![1,2,3];
+    /// let vec2 = vec.split_off(1);
+    /// assert_eq!(vec, [1]);
+    /// assert_eq!(vec2, [2, 3]);
+    /// ```
+    #[inline]
+    #[stable(feature = "split_off", since = "1.4.0")]
+    pub fn split_off(&mut self, at: usize) -> Self {
+        assert!(at <= self.len(), "`at` out of bounds");
+
+        let other_len = self.len - at;
+        let mut other = Vec::with_capacity(other_len);
+
+        // Unsafely `set_len` and copy items to `other`.
+        unsafe {
+            self.set_len(at);
+            other.set_len(other_len);
+
+            ptr::copy_nonoverlapping(self.as_ptr().offset(at as isize),
+                                     other.as_mut_ptr(),
+                                     other.len());
+        }
+        other
+    }
+}
+
+impl<T: Clone> Vec<T> {
+    /// Resizes the `Vec` in-place so that `len()` is equal to `new_len`.
+    ///
+    /// If `new_len` is greater than `len()`, the `Vec` is extended by the
+    /// difference, with each additional slot filled with `value`.
+    /// If `new_len` is less than `len()`, the `Vec` is simply truncated.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut vec = vec!["hello"];
+    /// vec.resize(3, "world");
+    /// assert_eq!(vec, ["hello", "world", "world"]);
+    ///
+    /// let mut vec = vec![1, 2, 3, 4];
+    /// vec.resize(2, 0);
+    /// assert_eq!(vec, [1, 2]);
+    /// ```
+    #[stable(feature = "vec_resize", since = "1.5.0")]
+    pub fn resize(&mut self, new_len: usize, value: T) {
+        let len = self.len();
+
+        if new_len > len {
+            self.extend_with_element(new_len - len, value);
+        } else {
+            self.truncate(new_len);
+        }
+    }
+
+    /// Extend the vector by `n` additional clones of `value`.
+    fn extend_with_element(&mut self, n: usize, value: T) {
+        self.reserve(n);
+
+        unsafe {
+            let len = self.len();
+            let mut ptr = self.as_mut_ptr().offset(len as isize);
+            // Write all elements except the last one
+            for i in 1..n {
+                ptr::write(ptr, value.clone());
+                ptr = ptr.offset(1);
+                // Increment the length in every step in case clone() panics
+                self.set_len(len + i);
+            }
+
+            if n > 0 {
+                // We can write the last element directly without cloning needlessly
+                ptr::write(ptr, value);
+                self.set_len(len + n);
+            }
+        }
+    }
+
+    /// Appends all elements in a slice to the `Vec`.
+    ///
+    /// Iterates over the slice `other`, clones each element, and then appends
+    /// it to this `Vec`. The `other` vector is traversed in-order.
+    ///
+    /// Note that this function is same as `extend` except that it is
+    /// specialized to work with slices instead. If and when Rust gets
+    /// specialization this function will likely be deprecated (but still
+    /// available).
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut vec = vec![1];
+    /// vec.extend_from_slice(&[2, 3, 4]);
+    /// assert_eq!(vec, [1, 2, 3, 4]);
+    /// ```
+    #[stable(feature = "vec_extend_from_slice", since = "1.6.0")]
+    pub fn extend_from_slice(&mut self, other: &[T]) {
+        self.reserve(other.len());
+
+        for i in 0..other.len() {
+            let len = self.len();
+
+            // Unsafe code so this can be optimised to a memcpy (or something
+            // similarly fast) when T is Copy. LLVM is easily confused, so any
+            // extra operations during the loop can prevent this optimisation.
+            unsafe {
+                ptr::write(self.get_unchecked_mut(len), other.get_unchecked(i).clone());
+                self.set_len(len + 1);
+            }
+        }
+    }
+}
+
+impl<T: PartialEq> Vec<T> {
+    /// Removes consecutive repeated elements in the vector.
+    ///
+    /// If the vector is sorted, this removes all duplicates.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut vec = vec![1, 2, 2, 3, 2];
+    ///
+    /// vec.dedup();
+    ///
+    /// assert_eq!(vec, [1, 2, 3, 2]);
+    /// ```
+    #[stable(feature = "rust1", since = "1.0.0")]
+    pub fn dedup(&mut self) {
+        unsafe {
+            // Although we have a mutable reference to `self`, we cannot make
+            // *arbitrary* changes. The `PartialEq` comparisons could panic, so we
+            // must ensure that the vector is in a valid state at all time.
+            //
+            // The way that we handle this is by using swaps; we iterate
+            // over all the elements, swapping as we go so that at the end
+            // the elements we wish to keep are in the front, and those we
+            // wish to reject are at the back. We can then truncate the
+            // vector. This operation is still O(n).
+            //
+            // Example: We start in this state, where `r` represents "next
+            // read" and `w` represents "next_write`.
+            //
+            //           r
+            //     +---+---+---+---+---+---+
+            //     | 0 | 1 | 1 | 2 | 3 | 3 |
+            //     +---+---+---+---+---+---+
+            //           w
+            //
+            // Comparing self[r] against self[w-1], this is not a duplicate, so
+            // we swap self[r] and self[w] (no effect as r==w) and then increment both
+            // r and w, leaving us with:
+            //
+            //               r
+            //     +---+---+---+---+---+---+
+            //     | 0 | 1 | 1 | 2 | 3 | 3 |
+            //     +---+---+---+---+---+---+
+            //               w
+            //
+            // Comparing self[r] against self[w-1], this value is a duplicate,
+            // so we increment `r` but leave everything else unchanged:
+            //
+            //                   r
+            //     +---+---+---+---+---+---+
+            //     | 0 | 1 | 1 | 2 | 3 | 3 |
+            //     +---+---+---+---+---+---+
+            //               w
+            //
+            // Comparing self[r] against self[w-1], this is not a duplicate,
+            // so swap self[r] and self[w] and advance r and w:
+            //
+            //                       r
+            //     +---+---+---+---+---+---+
+            //     | 0 | 1 | 2 | 1 | 3 | 3 |
+            //     +---+---+---+---+---+---+
+            //                   w
+            //
+            // Not a duplicate, repeat:
+            //
+            //                           r
+            //     +---+---+---+---+---+---+
+            //     | 0 | 1 | 2 | 3 | 1 | 3 |
+            //     +---+---+---+---+---+---+
+            //                       w
+            //
+            // Duplicate, advance r. End of vec. Truncate to w.
+
+            let ln = self.len();
+            if ln <= 1 {
+                return;
+            }
+
+            // Avoid bounds checks by using raw pointers.
+            let p = self.as_mut_ptr();
+            let mut r: usize = 1;
+            let mut w: usize = 1;
+
+            while r < ln {
+                let p_r = p.offset(r as isize);
+                let p_wm1 = p.offset((w - 1) as isize);
+                if *p_r != *p_wm1 {
+                    if r != w {
+                        let p_w = p_wm1.offset(1);
+                        mem::swap(&mut *p_r, &mut *p_w);
+                    }
+                    w += 1;
+                }
+                r += 1;
+            }
+
+            self.truncate(w);
+        }
+    }
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Internal methods and functions
+////////////////////////////////////////////////////////////////////////////////
+
+#[doc(hidden)]
+#[stable(feature = "rust1", since = "1.0.0")]
+pub fn from_elem<T: Clone>(elem: T, n: usize) -> Vec<T> {
+    let mut v = Vec::with_capacity(n);
+    v.extend_with_element(n, elem);
+    v
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Common trait implementations for Vec
+////////////////////////////////////////////////////////////////////////////////
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: Clone> Clone for Vec<T> {
+    #[cfg(not(test))]
+    fn clone(&self) -> Vec<T> {
+        <[T]>::to_vec(&**self)
+    }
+
+    // HACK(japaric): with cfg(test) the inherent `[T]::to_vec` method, which is
+    // required for this method definition, is not available. Instead use the
+    // `slice::to_vec`  function which is only available with cfg(test)
+    // NB see the slice::hack module in slice.rs for more information
+    #[cfg(test)]
+    fn clone(&self) -> Vec<T> {
+        ::slice::to_vec(&**self)
+    }
+
+    fn clone_from(&mut self, other: &Vec<T>) {
+        // drop anything in self that will not be overwritten
+        self.truncate(other.len());
+        let len = self.len();
+
+        // reuse the contained values' allocations/resources.
+        self.clone_from_slice(&other[..len]);
+
+        // self.len <= other.len due to the truncate above, so the
+        // slice here is always in-bounds.
+        self.extend_from_slice(&other[len..]);
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: Hash> Hash for Vec<T> {
+    #[inline]
+    fn hash<H: hash::Hasher>(&self, state: &mut H) {
+        Hash::hash(&**self, state)
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> Index<usize> for Vec<T> {
+    type Output = T;
+
+    #[inline]
+    fn index(&self, index: usize) -> &T {
+        // NB built-in indexing via `&[T]`
+        &(**self)[index]
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> IndexMut<usize> for Vec<T> {
+    #[inline]
+    fn index_mut(&mut self, index: usize) -> &mut T {
+        // NB built-in indexing via `&mut [T]`
+        &mut (**self)[index]
+    }
+}
+
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> ops::Index<ops::Range<usize>> for Vec<T> {
+    type Output = [T];
+
+    #[inline]
+    fn index(&self, index: ops::Range<usize>) -> &[T] {
+        Index::index(&**self, index)
+    }
+}
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> ops::Index<ops::RangeTo<usize>> for Vec<T> {
+    type Output = [T];
+
+    #[inline]
+    fn index(&self, index: ops::RangeTo<usize>) -> &[T] {
+        Index::index(&**self, index)
+    }
+}
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> ops::Index<ops::RangeFrom<usize>> for Vec<T> {
+    type Output = [T];
+
+    #[inline]
+    fn index(&self, index: ops::RangeFrom<usize>) -> &[T] {
+        Index::index(&**self, index)
+    }
+}
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> ops::Index<ops::RangeFull> for Vec<T> {
+    type Output = [T];
+
+    #[inline]
+    fn index(&self, _index: ops::RangeFull) -> &[T] {
+        self
+    }
+}
+#[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
+impl<T> ops::Index<ops::RangeInclusive<usize>> for Vec<T> {
+    type Output = [T];
+
+    #[inline]
+    fn index(&self, index: ops::RangeInclusive<usize>) -> &[T] {
+        Index::index(&**self, index)
+    }
+}
+#[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
+impl<T> ops::Index<ops::RangeToInclusive<usize>> for Vec<T> {
+    type Output = [T];
+
+    #[inline]
+    fn index(&self, index: ops::RangeToInclusive<usize>) -> &[T] {
+        Index::index(&**self, index)
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> ops::IndexMut<ops::Range<usize>> for Vec<T> {
+    #[inline]
+    fn index_mut(&mut self, index: ops::Range<usize>) -> &mut [T] {
+        IndexMut::index_mut(&mut **self, index)
+    }
+}
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> ops::IndexMut<ops::RangeTo<usize>> for Vec<T> {
+    #[inline]
+    fn index_mut(&mut self, index: ops::RangeTo<usize>) -> &mut [T] {
+        IndexMut::index_mut(&mut **self, index)
+    }
+}
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> ops::IndexMut<ops::RangeFrom<usize>> for Vec<T> {
+    #[inline]
+    fn index_mut(&mut self, index: ops::RangeFrom<usize>) -> &mut [T] {
+        IndexMut::index_mut(&mut **self, index)
+    }
+}
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> ops::IndexMut<ops::RangeFull> for Vec<T> {
+    #[inline]
+    fn index_mut(&mut self, _index: ops::RangeFull) -> &mut [T] {
+        self
+    }
+}
+#[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
+impl<T> ops::IndexMut<ops::RangeInclusive<usize>> for Vec<T> {
+    #[inline]
+    fn index_mut(&mut self, index: ops::RangeInclusive<usize>) -> &mut [T] {
+        IndexMut::index_mut(&mut **self, index)
+    }
+}
+#[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
+impl<T> ops::IndexMut<ops::RangeToInclusive<usize>> for Vec<T> {
+    #[inline]
+    fn index_mut(&mut self, index: ops::RangeToInclusive<usize>) -> &mut [T] {
+        IndexMut::index_mut(&mut **self, index)
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> ops::Deref for Vec<T> {
+    type Target = [T];
+
+    fn deref(&self) -> &[T] {
+        unsafe {
+            let p = self.buf.ptr();
+            assume(!p.is_null());
+            slice::from_raw_parts(p, self.len)
+        }
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> ops::DerefMut for Vec<T> {
+    fn deref_mut(&mut self) -> &mut [T] {
+        unsafe {
+            let ptr = self.buf.ptr();
+            assume(!ptr.is_null());
+            slice::from_raw_parts_mut(ptr, self.len)
+        }
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> FromIterator<T> for Vec<T> {
+    #[inline]
+    fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Vec<T> {
+        // Unroll the first iteration, as the vector is going to be
+        // expanded on this iteration in every case when the iterable is not
+        // empty, but the loop in extend_desugared() is not going to see the
+        // vector being full in the few subsequent loop iterations.
+        // So we get better branch prediction.
+        let mut iterator = iter.into_iter();
+        let mut vector = match iterator.next() {
+            None => return Vec::new(),
+            Some(element) => {
+                let (lower, _) = iterator.size_hint();
+                let mut vector = Vec::with_capacity(lower.saturating_add(1));
+                unsafe {
+                    ptr::write(vector.get_unchecked_mut(0), element);
+                    vector.set_len(1);
+                }
+                vector
+            }
+        };
+        vector.extend_desugared(iterator);
+        vector
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> IntoIterator for Vec<T> {
+    type Item = T;
+    type IntoIter = IntoIter<T>;
+
+    /// Creates a consuming iterator, that is, one that moves each value out of
+    /// the vector (from start to end). The vector cannot be used after calling
+    /// this.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let v = vec!["a".to_string(), "b".to_string()];
+    /// for s in v.into_iter() {
+    ///     // s has type String, not &String
+    ///     println!("{}", s);
+    /// }
+    /// ```
+    #[inline]
+    fn into_iter(mut self) -> IntoIter<T> {
+        unsafe {
+            let ptr = self.as_mut_ptr();
+            assume(!ptr.is_null());
+            let begin = ptr as *const T;
+            let end = if mem::size_of::<T>() == 0 {
+                arith_offset(ptr as *const i8, self.len() as isize) as *const T
+            } else {
+                ptr.offset(self.len() as isize) as *const T
+            };
+            let buf = ptr::read(&self.buf);
+            mem::forget(self);
+            IntoIter {
+                _buf: buf,
+                ptr: begin,
+                end: end,
+            }
+        }
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<'a, T> IntoIterator for &'a Vec<T> {
+    type Item = &'a T;
+    type IntoIter = slice::Iter<'a, T>;
+
+    fn into_iter(self) -> slice::Iter<'a, T> {
+        self.iter()
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<'a, T> IntoIterator for &'a mut Vec<T> {
+    type Item = &'a mut T;
+    type IntoIter = slice::IterMut<'a, T>;
+
+    fn into_iter(mut self) -> slice::IterMut<'a, T> {
+        self.iter_mut()
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> Extend<T> for Vec<T> {
+    #[inline]
+    fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I) {
+        self.extend_desugared(iter.into_iter())
+    }
+}
+
+impl<T> Vec<T> {
+    fn extend_desugared<I: Iterator<Item = T>>(&mut self, mut iterator: I) {
+        // This function should be the moral equivalent of:
+        //
+        //      for item in iterator {
+        //          self.push(item);
+        //      }
+        while let Some(element) = iterator.next() {
+            let len = self.len();
+            if len == self.capacity() {
+                let (lower, _) = iterator.size_hint();
+                self.reserve(lower.saturating_add(1));
+            }
+            unsafe {
+                ptr::write(self.get_unchecked_mut(len), element);
+                // NB can't overflow since we would have had to alloc the address space
+                self.set_len(len + 1);
+            }
+        }
+    }
+}
+
+#[stable(feature = "extend_ref", since = "1.2.0")]
+impl<'a, T: 'a + Copy> Extend<&'a T> for Vec<T> {
+    fn extend<I: IntoIterator<Item = &'a T>>(&mut self, iter: I) {
+        self.extend(iter.into_iter().cloned());
+    }
+}
+
+macro_rules! __impl_slice_eq1 {
+    ($Lhs: ty, $Rhs: ty) => {
+        __impl_slice_eq1! { $Lhs, $Rhs, Sized }
+    };
+    ($Lhs: ty, $Rhs: ty, $Bound: ident) => {
+        #[stable(feature = "rust1", since = "1.0.0")]
+        impl<'a, 'b, A: $Bound, B> PartialEq<$Rhs> for $Lhs where A: PartialEq<B> {
+            #[inline]
+            fn eq(&self, other: &$Rhs) -> bool { self[..] == other[..] }
+            #[inline]
+            fn ne(&self, other: &$Rhs) -> bool { self[..] != other[..] }
+        }
+    }
+}
+
+__impl_slice_eq1! { Vec<A>, Vec<B> }
+__impl_slice_eq1! { Vec<A>, &'b [B] }
+__impl_slice_eq1! { Vec<A>, &'b mut [B] }
+__impl_slice_eq1! { Cow<'a, [A]>, &'b [B], Clone }
+__impl_slice_eq1! { Cow<'a, [A]>, &'b mut [B], Clone }
+__impl_slice_eq1! { Cow<'a, [A]>, Vec<B>, Clone }
+
+macro_rules! array_impls {
+    ($($N: expr)+) => {
+        $(
+            // NOTE: some less important impls are omitted to reduce code bloat
+            __impl_slice_eq1! { Vec<A>, [B; $N] }
+            __impl_slice_eq1! { Vec<A>, &'b [B; $N] }
+            // __impl_slice_eq1! { Vec<A>, &'b mut [B; $N] }
+            // __impl_slice_eq1! { Cow<'a, [A]>, [B; $N], Clone }
+            // __impl_slice_eq1! { Cow<'a, [A]>, &'b [B; $N], Clone }
+            // __impl_slice_eq1! { Cow<'a, [A]>, &'b mut [B; $N], Clone }
+        )+
+    }
+}
+
+array_impls! {
+     0  1  2  3  4  5  6  7  8  9
+    10 11 12 13 14 15 16 17 18 19
+    20 21 22 23 24 25 26 27 28 29
+    30 31 32
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: PartialOrd> PartialOrd for Vec<T> {
+    #[inline]
+    fn partial_cmp(&self, other: &Vec<T>) -> Option<Ordering> {
+        PartialOrd::partial_cmp(&**self, &**other)
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: Eq> Eq for Vec<T> {}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: Ord> Ord for Vec<T> {
+    #[inline]
+    fn cmp(&self, other: &Vec<T>) -> Ordering {
+        Ord::cmp(&**self, &**other)
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> Drop for Vec<T> {
+    #[unsafe_destructor_blind_to_params]
+    fn drop(&mut self) {
+        if self.buf.unsafe_no_drop_flag_needs_drop() {
+            unsafe {
+                // use drop for [T]
+                ptr::drop_in_place(&mut self[..]);
+            }
+        }
+        // RawVec handles deallocation
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> Default for Vec<T> {
+    fn default() -> Vec<T> {
+        Vec::new()
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T: fmt::Debug> fmt::Debug for Vec<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fmt::Debug::fmt(&**self, f)
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> AsRef<Vec<T>> for Vec<T> {
+    fn as_ref(&self) -> &Vec<T> {
+        self
+    }
+}
+
+#[stable(feature = "vec_as_mut", since = "1.5.0")]
+impl<T> AsMut<Vec<T>> for Vec<T> {
+    fn as_mut(&mut self) -> &mut Vec<T> {
+        self
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> AsRef<[T]> for Vec<T> {
+    fn as_ref(&self) -> &[T] {
+        self
+    }
+}
+
+#[stable(feature = "vec_as_mut", since = "1.5.0")]
+impl<T> AsMut<[T]> for Vec<T> {
+    fn as_mut(&mut self) -> &mut [T] {
+        self
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<'a, T: Clone> From<&'a [T]> for Vec<T> {
+    #[cfg(not(test))]
+    fn from(s: &'a [T]) -> Vec<T> {
+        s.to_vec()
+    }
+    #[cfg(test)]
+    fn from(s: &'a [T]) -> Vec<T> {
+        ::slice::to_vec(s)
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<'a> From<&'a str> for Vec<u8> {
+    fn from(s: &'a str) -> Vec<u8> {
+        From::from(s.as_bytes())
+    }
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Clone-on-write
+////////////////////////////////////////////////////////////////////////////////
+
+#[stable(feature = "cow_from_vec", since = "1.7.0")]
+impl<'a, T: Clone> From<&'a [T]> for Cow<'a, [T]> {
+    fn from(s: &'a [T]) -> Cow<'a, [T]> {
+        Cow::Borrowed(s)
+    }
+}
+
+#[stable(feature = "cow_from_vec", since = "1.7.0")]
+impl<'a, T: Clone> From<Vec<T>> for Cow<'a, [T]> {
+    fn from(v: Vec<T>) -> Cow<'a, [T]> {
+        Cow::Owned(v)
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<'a, T> FromIterator<T> for Cow<'a, [T]> where T: Clone {
+    fn from_iter<I: IntoIterator<Item = T>>(it: I) -> Cow<'a, [T]> {
+        Cow::Owned(FromIterator::from_iter(it))
+    }
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Iterators
+////////////////////////////////////////////////////////////////////////////////
+
+/// An iterator that moves out of a vector.
+#[stable(feature = "rust1", since = "1.0.0")]
+pub struct IntoIter<T> {
+    _buf: RawVec<T>,
+    ptr: *const T,
+    end: *const T,
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+unsafe impl<T: Send> Send for IntoIter<T> {}
+#[stable(feature = "rust1", since = "1.0.0")]
+unsafe impl<T: Sync> Sync for IntoIter<T> {}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> Iterator for IntoIter<T> {
+    type Item = T;
+
+    #[inline]
+    fn next(&mut self) -> Option<T> {
+        unsafe {
+            if self.ptr == self.end {
+                None
+            } else {
+                if mem::size_of::<T>() == 0 {
+                    // purposefully don't use 'ptr.offset' because for
+                    // vectors with 0-size elements this would return the
+                    // same pointer.
+                    self.ptr = arith_offset(self.ptr as *const i8, 1) as *const T;
+
+                    // Use a non-null pointer value
+                    Some(ptr::read(EMPTY as *mut T))
+                } else {
+                    let old = self.ptr;
+                    self.ptr = self.ptr.offset(1);
+
+                    Some(ptr::read(old))
+                }
+            }
+        }
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let diff = (self.end as usize) - (self.ptr as usize);
+        let size = mem::size_of::<T>();
+        let exact = diff /
+                    (if size == 0 {
+                         1
+                     } else {
+                         size
+                     });
+        (exact, Some(exact))
+    }
+
+    #[inline]
+    fn count(self) -> usize {
+        self.size_hint().0
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> DoubleEndedIterator for IntoIter<T> {
+    #[inline]
+    fn next_back(&mut self) -> Option<T> {
+        unsafe {
+            if self.end == self.ptr {
+                None
+            } else {
+                if mem::size_of::<T>() == 0 {
+                    // See above for why 'ptr.offset' isn't used
+                    self.end = arith_offset(self.end as *const i8, -1) as *const T;
+
+                    // Use a non-null pointer value
+                    Some(ptr::read(EMPTY as *mut T))
+                } else {
+                    self.end = self.end.offset(-1);
+
+                    Some(ptr::read(self.end))
+                }
+            }
+        }
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> ExactSizeIterator for IntoIter<T> {}
+
+#[stable(feature = "vec_into_iter_clone", since = "1.8.0")]
+impl<T: Clone> Clone for IntoIter<T> {
+    fn clone(&self) -> IntoIter<T> {
+        unsafe {
+            slice::from_raw_parts(self.ptr, self.len()).to_owned().into_iter()
+        }
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<T> Drop for IntoIter<T> {
+    #[unsafe_destructor_blind_to_params]
+    fn drop(&mut self) {
+        // destroy the remaining elements
+        for _x in self {}
+
+        // RawVec handles deallocation
+    }
+}
+
+/// A draining iterator for `Vec<T>`.
+#[stable(feature = "drain", since = "1.6.0")]
+pub struct Drain<'a, T: 'a> {
+    /// Index of tail to preserve
+    tail_start: usize,
+    /// Length of tail
+    tail_len: usize,
+    /// Current remaining range to remove
+    iter: slice::IterMut<'a, T>,
+    vec: *mut Vec<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> Iterator for Drain<'a, T> {
+    type Item = T;
+
+    #[inline]
+    fn next(&mut self) -> Option<T> {
+        self.iter.next().map(|elt| unsafe { ptr::read(elt as *const _) })
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.iter.size_hint()
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<'a, T> DoubleEndedIterator for Drain<'a, T> {
+    #[inline]
+    fn next_back(&mut self) -> Option<T> {
+        self.iter.next_back().map(|elt| unsafe { ptr::read(elt as *const _) })
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<'a, T> Drop for Drain<'a, T> {
+    fn drop(&mut self) {
+        // exhaust self first
+        while let Some(_) = self.next() {}
+
+        if self.tail_len > 0 {
+            unsafe {
+                let source_vec = &mut *self.vec;
+                // memmove back untouched tail, update to new length
+                let start = source_vec.len();
+                let tail = self.tail_start;
+                let src = source_vec.as_ptr().offset(tail as isize);
+                let dst = source_vec.as_mut_ptr().offset(start as isize);
+                ptr::copy(src, dst, self.tail_len);
+                source_vec.set_len(start + self.tail_len);
+            }
+        }
+    }
+}
+
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<'a, T> ExactSizeIterator for Drain<'a, T> {}