moved collections from libextra into libcollections

1 files changed, 858 insertions, 0 deletions

diff --git a/src/libcollections/ringbuf.rs b/src/libcollections/ringbuf.rs
new file mode 100644
index 00000000000..933fe2048e4
--- /dev/null
+++ b/src/libcollections/ringbuf.rs
@@ -0,0 +1,858 @@
+// Copyright 2012-2013 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 double-ended queue implemented as a circular buffer
+//!
+//! RingBuf implements the trait Deque. It should be imported with `use
+//! extra::container::Deque`.
+
+use std::num;
+use std::vec;
+use std::iter::{Rev, RandomAccessIterator};
+
+use deque::Deque;
+
+use serialize::{Encodable, Decodable, Encoder, Decoder};
+
+static INITIAL_CAPACITY: uint = 8u; // 2^3
+static MINIMUM_CAPACITY: uint = 2u;
+
+/// RingBuf is a circular buffer that implements Deque.
+#[deriving(Clone)]
+pub struct RingBuf<T> {
+    priv nelts: uint,
+    priv lo: uint,
+    priv elts: ~[Option<T>]
+}
+
+impl<T> Container for RingBuf<T> {
+    /// Return the number of elements in the RingBuf
+    fn len(&self) -> uint { self.nelts }
+}
+
+impl<T> Mutable for RingBuf<T> {
+    /// Clear the RingBuf, removing all values.
+    fn clear(&mut self) {
+        for x in self.elts.mut_iter() { *x = None }
+        self.nelts = 0;
+        self.lo = 0;
+    }
+}
+
+impl<T> Deque<T> for RingBuf<T> {
+    /// Return a reference to the first element in the RingBuf
+    fn front<'a>(&'a self) -> Option<&'a T> {
+        if self.nelts > 0 { Some(self.get(0)) } else { None }
+    }
+
+    /// Return a mutable reference to the first element in the RingBuf
+    fn front_mut<'a>(&'a mut self) -> Option<&'a mut T> {
+        if self.nelts > 0 { Some(self.get_mut(0)) } else { None }
+    }
+
+    /// Return a reference to the last element in the RingBuf
+    fn back<'a>(&'a self) -> Option<&'a T> {
+        if self.nelts > 0 { Some(self.get(self.nelts - 1)) } else { None }
+    }
+
+    /// Return a mutable reference to the last element in the RingBuf
+    fn back_mut<'a>(&'a mut self) -> Option<&'a mut T> {
+        if self.nelts > 0 { Some(self.get_mut(self.nelts - 1)) } else { None }
+    }
+
+    /// Remove and return the first element in the RingBuf, or None if it is empty
+    fn pop_front(&mut self) -> Option<T> {
+        let result = self.elts[self.lo].take();
+        if result.is_some() {
+            self.lo = (self.lo + 1u) % self.elts.len();
+            self.nelts -= 1u;
+        }
+        result
+    }
+
+    /// Remove and return the last element in the RingBuf, or None if it is empty
+    fn pop_back(&mut self) -> Option<T> {
+        if self.nelts > 0 {
+            self.nelts -= 1;
+            let hi = self.raw_index(self.nelts);
+            self.elts[hi].take()
+        } else {
+            None
+        }
+    }
+
+    /// Prepend an element to the RingBuf
+    fn push_front(&mut self, t: T) {
+        if self.nelts == self.elts.len() {
+            grow(self.nelts, &mut self.lo, &mut self.elts);
+        }
+        if self.lo == 0u {
+            self.lo = self.elts.len() - 1u;
+        } else { self.lo -= 1u; }
+        self.elts[self.lo] = Some(t);
+        self.nelts += 1u;
+    }
+
+    /// Append an element to the RingBuf
+    fn push_back(&mut self, t: T) {
+        if self.nelts == self.elts.len() {
+            grow(self.nelts, &mut self.lo, &mut self.elts);
+        }
+        let hi = self.raw_index(self.nelts);
+        self.elts[hi] = Some(t);
+        self.nelts += 1u;
+    }
+}
+
+impl<T> RingBuf<T> {
+    /// Create an empty RingBuf
+    pub fn new() -> RingBuf<T> {
+        RingBuf::with_capacity(INITIAL_CAPACITY)
+    }
+
+    /// Create an empty RingBuf with space for at least `n` elements.
+    pub fn with_capacity(n: uint) -> RingBuf<T> {
+        RingBuf{nelts: 0, lo: 0,
+              elts: vec::from_fn(num::max(MINIMUM_CAPACITY, n), |_| None)}
+    }
+
+    /// Retrieve an element in the RingBuf by index
+    ///
+    /// Fails if there is no element with the given index
+    pub fn get<'a>(&'a self, i: uint) -> &'a T {
+        let idx = self.raw_index(i);
+        match self.elts[idx] {
+            None => fail!(),
+            Some(ref v) => v
+        }
+    }
+
+    /// Retrieve an element in the RingBuf by index
+    ///
+    /// Fails if there is no element with the given index
+    pub fn get_mut<'a>(&'a mut self, i: uint) -> &'a mut T {
+        let idx = self.raw_index(i);
+        match self.elts[idx] {
+            None => fail!(),
+            Some(ref mut v) => v
+        }
+    }
+
+    /// Swap elements at indices `i` and `j`
+    ///
+    /// `i` and `j` may be equal.
+    ///
+    /// Fails if there is no element with the given index
+    pub fn swap(&mut self, i: uint, j: uint) {
+        assert!(i < self.len());
+        assert!(j < self.len());
+        let ri = self.raw_index(i);
+        let rj = self.raw_index(j);
+        self.elts.swap(ri, rj);
+    }
+
+    /// Return index in underlying vec for a given logical element index
+    fn raw_index(&self, idx: uint) -> uint {
+        raw_index(self.lo, self.elts.len(), idx)
+    }
+
+    /// Reserve capacity for exactly `n` elements in the given RingBuf,
+    /// doing nothing if `self`'s capacity is already equal to or greater
+    /// than the requested capacity
+    ///
+    /// # Arguments
+    ///
+    /// * n - The number of elements to reserve space for
+    pub fn reserve_exact(&mut self, n: uint) {
+        self.elts.reserve_exact(n);
+    }
+
+    /// Reserve capacity for at least `n` elements in the given RingBuf,
+    /// over-allocating in case the caller needs to reserve additional
+    /// space.
+    ///
+    /// Do nothing if `self`'s capacity is already equal to or greater
+    /// than the requested capacity.
+    ///
+    /// # Arguments
+    ///
+    /// * n - The number of elements to reserve space for
+    pub fn reserve(&mut self, n: uint) {
+        self.elts.reserve(n);
+    }
+
+    /// Front-to-back iterator.
+    pub fn iter<'a>(&'a self) -> Items<'a, T> {
+        Items{index: 0, rindex: self.nelts, lo: self.lo, elts: self.elts}
+    }
+
+    /// Back-to-front iterator.
+    pub fn rev_iter<'a>(&'a self) -> Rev<Items<'a, T>> {
+        self.iter().rev()
+    }
+
+    /// Front-to-back iterator which returns mutable values.
+    pub fn mut_iter<'a>(&'a mut self) -> MutItems<'a, T> {
+        let start_index = raw_index(self.lo, self.elts.len(), 0);
+        let end_index = raw_index(self.lo, self.elts.len(), self.nelts);
+
+        // Divide up the array
+        if end_index <= start_index {
+            // Items to iterate goes from:
+            //    start_index to self.elts.len()
+            // and then
+            //    0 to end_index
+            let (temp, remaining1) = self.elts.mut_split_at(start_index);
+            let (remaining2, _) = temp.mut_split_at(end_index);
+            MutItems { remaining1: remaining1,
+                                 remaining2: remaining2,
+                                 nelts: self.nelts }
+        } else {
+            // Items to iterate goes from start_index to end_index:
+            let (empty, elts) = self.elts.mut_split_at(0);
+            let remaining1 = elts.mut_slice(start_index, end_index);
+            MutItems { remaining1: remaining1,
+                                 remaining2: empty,
+                                 nelts: self.nelts }
+        }
+    }
+
+    /// Back-to-front iterator which returns mutable values.
+    pub fn mut_rev_iter<'a>(&'a mut self) -> Rev<MutItems<'a, T>> {
+        self.mut_iter().rev()
+    }
+}
+
+/// RingBuf iterator
+pub struct Items<'a, T> {
+    priv lo: uint,
+    priv index: uint,
+    priv rindex: uint,
+    priv elts: &'a [Option<T>],
+}
+
+impl<'a, T> Iterator<&'a T> for Items<'a, T> {
+    #[inline]
+    fn next(&mut self) -> Option<&'a T> {
+        if self.index == self.rindex {
+            return None;
+        }
+        let raw_index = raw_index(self.lo, self.elts.len(), self.index);
+        self.index += 1;
+        Some(self.elts[raw_index].get_ref())
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (uint, Option<uint>) {
+        let len = self.rindex - self.index;
+        (len, Some(len))
+    }
+}
+
+impl<'a, T> DoubleEndedIterator<&'a T> for Items<'a, T> {
+    #[inline]
+    fn next_back(&mut self) -> Option<&'a T> {
+        if self.index == self.rindex {
+            return None;
+        }
+        self.rindex -= 1;
+        let raw_index = raw_index(self.lo, self.elts.len(), self.rindex);
+        Some(self.elts[raw_index].get_ref())
+    }
+}
+
+impl<'a, T> ExactSize<&'a T> for Items<'a, T> {}
+
+impl<'a, T> RandomAccessIterator<&'a T> for Items<'a, T> {
+    #[inline]
+    fn indexable(&self) -> uint { self.rindex - self.index }
+
+    #[inline]
+    fn idx(&self, j: uint) -> Option<&'a T> {
+        if j >= self.indexable() {
+            None
+        } else {
+            let raw_index = raw_index(self.lo, self.elts.len(), self.index + j);
+            Some(self.elts[raw_index].get_ref())
+        }
+    }
+}
+
+/// RingBuf mutable iterator
+pub struct MutItems<'a, T> {
+    priv remaining1: &'a mut [Option<T>],
+    priv remaining2: &'a mut [Option<T>],
+    priv nelts: uint,
+}
+
+impl<'a, T> Iterator<&'a mut T> for MutItems<'a, T> {
+    #[inline]
+    fn next(&mut self) -> Option<&'a mut T> {
+        if self.nelts == 0 {
+            return None;
+        }
+        let r = if self.remaining1.len() > 0 {
+            &mut self.remaining1
+        } else {
+            assert!(self.remaining2.len() > 0);
+            &mut self.remaining2
+        };
+        self.nelts -= 1;
+        Some(r.mut_shift_ref().unwrap().get_mut_ref())
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (uint, Option<uint>) {
+        (self.nelts, Some(self.nelts))
+    }
+}
+
+impl<'a, T> DoubleEndedIterator<&'a mut T> for MutItems<'a, T> {
+    #[inline]
+    fn next_back(&mut self) -> Option<&'a mut T> {
+        if self.nelts == 0 {
+            return None;
+        }
+        let r = if self.remaining2.len() > 0 {
+            &mut self.remaining2
+        } else {
+            assert!(self.remaining1.len() > 0);
+            &mut self.remaining1
+        };
+        self.nelts -= 1;
+        Some(r.mut_pop_ref().unwrap().get_mut_ref())
+    }
+}
+
+impl<'a, T> ExactSize<&'a mut T> for MutItems<'a, T> {}
+
+/// Grow is only called on full elts, so nelts is also len(elts), unlike
+/// elsewhere.
+fn grow<T>(nelts: uint, loptr: &mut uint, elts: &mut ~[Option<T>]) {
+    assert_eq!(nelts, elts.len());
+    let lo = *loptr;
+    let newlen = nelts * 2;
+    elts.reserve(newlen);
+
+    /* fill with None */
+    for _ in range(elts.len(), elts.capacity()) {
+        elts.push(None);
+    }
+
+    /*
+      Move the shortest half into the newly reserved area.
+      lo ---->|
+      nelts ----------->|
+        [o o o|o o o o o]
+      A [. . .|o o o o o o o o|. . . . .]
+      B [o o o|. . . . . . . .|o o o o o]
+     */
+
+    assert!(newlen - nelts/2 >= nelts);
+    if lo <= (nelts - lo) { // A
+        for i in range(0u, lo) {
+            elts.swap(i, nelts + i);
+        }
+    } else {                // B
+        for i in range(lo, nelts) {
+            elts.swap(i, newlen - nelts + i);
+        }
+        *loptr += newlen - nelts;
+    }
+}
+
+/// Return index in underlying vec for a given logical element index
+fn raw_index(lo: uint, len: uint, index: uint) -> uint {
+    if lo >= len - index {
+        lo + index - len
+    } else {
+        lo + index
+    }
+}
+
+impl<A: Eq> Eq for RingBuf<A> {
+    fn eq(&self, other: &RingBuf<A>) -> bool {
+        self.nelts == other.nelts &&
+            self.iter().zip(other.iter()).all(|(a, b)| a.eq(b))
+    }
+    fn ne(&self, other: &RingBuf<A>) -> bool {
+        !self.eq(other)
+    }
+}
+
+impl<A> FromIterator<A> for RingBuf<A> {
+    fn from_iterator<T: Iterator<A>>(iterator: &mut T) -> RingBuf<A> {
+        let (lower, _) = iterator.size_hint();
+        let mut deq = RingBuf::with_capacity(lower);
+        deq.extend(iterator);
+        deq
+    }
+}
+
+impl<A> Extendable<A> for RingBuf<A> {
+    fn extend<T: Iterator<A>>(&mut self, iterator: &mut T) {
+        for elt in *iterator {
+            self.push_back(elt);
+        }
+    }
+}
+
+impl<
+    S: Encoder,
+    T: Encodable<S>
+> Encodable<S> for RingBuf<T> {
+    fn encode(&self, s: &mut S) {
+        s.emit_seq(self.len(), |s| {
+            for (i, e) in self.iter().enumerate() {
+                s.emit_seq_elt(i, |s| e.encode(s));
+            }
+        })
+    }
+}
+
+impl<D:Decoder,T:Decodable<D>> Decodable<D> for RingBuf<T> {
+    fn decode(d: &mut D) -> RingBuf<T> {
+        let mut deque = RingBuf::new();
+        d.read_seq(|d, len| {
+            for i in range(0u, len) {
+                deque.push_back(d.read_seq_elt(i, |d| Decodable::decode(d)));
+            }
+        });
+        deque
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use deque::Deque;
+    use extra::test;
+    use std::clone::Clone;
+    use std::cmp::Eq;
+    use super::RingBuf;
+
+    #[test]
+    fn test_simple() {
+        let mut d = RingBuf::new();
+        assert_eq!(d.len(), 0u);
+        d.push_front(17);
+        d.push_front(42);
+        d.push_back(137);
+        assert_eq!(d.len(), 3u);
+        d.push_back(137);
+        assert_eq!(d.len(), 4u);
+        debug!("{:?}", d.front());
+        assert_eq!(*d.front().unwrap(), 42);
+        debug!("{:?}", d.back());
+        assert_eq!(*d.back().unwrap(), 137);
+        let mut i = d.pop_front();
+        debug!("{:?}", i);
+        assert_eq!(i, Some(42));
+        i = d.pop_back();
+        debug!("{:?}", i);
+        assert_eq!(i, Some(137));
+        i = d.pop_back();
+        debug!("{:?}", i);
+        assert_eq!(i, Some(137));
+        i = d.pop_back();
+        debug!("{:?}", i);
+        assert_eq!(i, Some(17));
+        assert_eq!(d.len(), 0u);
+        d.push_back(3);
+        assert_eq!(d.len(), 1u);
+        d.push_front(2);
+        assert_eq!(d.len(), 2u);
+        d.push_back(4);
+        assert_eq!(d.len(), 3u);
+        d.push_front(1);
+        assert_eq!(d.len(), 4u);
+        debug!("{:?}", d.get(0));
+        debug!("{:?}", d.get(1));
+        debug!("{:?}", d.get(2));
+        debug!("{:?}", d.get(3));
+        assert_eq!(*d.get(0), 1);
+        assert_eq!(*d.get(1), 2);
+        assert_eq!(*d.get(2), 3);
+        assert_eq!(*d.get(3), 4);
+    }
+
+    #[test]
+    fn test_boxes() {
+        let a: @int = @5;
+        let b: @int = @72;
+        let c: @int = @64;
+        let d: @int = @175;
+
+        let mut deq = RingBuf::new();
+        assert_eq!(deq.len(), 0);
+        deq.push_front(a);
+        deq.push_front(b);
+        deq.push_back(c);
+        assert_eq!(deq.len(), 3);
+        deq.push_back(d);
+        assert_eq!(deq.len(), 4);
+        assert_eq!(deq.front(), Some(&b));
+        assert_eq!(deq.back(), Some(&d));
+        assert_eq!(deq.pop_front(), Some(b));
+        assert_eq!(deq.pop_back(), Some(d));
+        assert_eq!(deq.pop_back(), Some(c));
+        assert_eq!(deq.pop_back(), Some(a));
+        assert_eq!(deq.len(), 0);
+        deq.push_back(c);
+        assert_eq!(deq.len(), 1);
+        deq.push_front(b);
+        assert_eq!(deq.len(), 2);
+        deq.push_back(d);
+        assert_eq!(deq.len(), 3);
+        deq.push_front(a);
+        assert_eq!(deq.len(), 4);
+        assert_eq!(*deq.get(0), a);
+        assert_eq!(*deq.get(1), b);
+        assert_eq!(*deq.get(2), c);
+        assert_eq!(*deq.get(3), d);
+    }
+
+    #[cfg(test)]
+    fn test_parameterized<T:Clone + Eq>(a: T, b: T, c: T, d: T) {
+        let mut deq = RingBuf::new();
+        assert_eq!(deq.len(), 0);
+        deq.push_front(a.clone());
+        deq.push_front(b.clone());
+        deq.push_back(c.clone());
+        assert_eq!(deq.len(), 3);
+        deq.push_back(d.clone());
+        assert_eq!(deq.len(), 4);
+        assert_eq!((*deq.front().unwrap()).clone(), b.clone());
+        assert_eq!((*deq.back().unwrap()).clone(), d.clone());
+        assert_eq!(deq.pop_front().unwrap(), b.clone());
+        assert_eq!(deq.pop_back().unwrap(), d.clone());
+        assert_eq!(deq.pop_back().unwrap(), c.clone());
+        assert_eq!(deq.pop_back().unwrap(), a.clone());
+        assert_eq!(deq.len(), 0);
+        deq.push_back(c.clone());
+        assert_eq!(deq.len(), 1);
+        deq.push_front(b.clone());
+        assert_eq!(deq.len(), 2);
+        deq.push_back(d.clone());
+        assert_eq!(deq.len(), 3);
+        deq.push_front(a.clone());
+        assert_eq!(deq.len(), 4);
+        assert_eq!((*deq.get(0)).clone(), a.clone());
+        assert_eq!((*deq.get(1)).clone(), b.clone());
+        assert_eq!((*deq.get(2)).clone(), c.clone());
+        assert_eq!((*deq.get(3)).clone(), d.clone());
+    }
+
+    #[test]
+    fn test_push_front_grow() {
+        let mut deq = RingBuf::new();
+        for i in range(0u, 66) {
+            deq.push_front(i);
+        }
+        assert_eq!(deq.len(), 66);
+
+        for i in range(0u, 66) {
+            assert_eq!(*deq.get(i), 65 - i);
+        }
+
+        let mut deq = RingBuf::new();
+        for i in range(0u, 66) {
+            deq.push_back(i);
+        }
+
+        for i in range(0u, 66) {
+            assert_eq!(*deq.get(i), i);
+        }
+    }
+
+    #[bench]
+    fn bench_new(b: &mut test::BenchHarness) {
+        b.iter(|| {
+            let _: RingBuf<u64> = RingBuf::new();
+        })
+    }
+
+    #[bench]
+    fn bench_push_back(b: &mut test::BenchHarness) {
+        let mut deq = RingBuf::new();
+        b.iter(|| {
+            deq.push_back(0);
+        })
+    }
+
+    #[bench]
+    fn bench_push_front(b: &mut test::BenchHarness) {
+        let mut deq = RingBuf::new();
+        b.iter(|| {
+            deq.push_front(0);
+        })
+    }
+
+    #[bench]
+    fn bench_grow(b: &mut test::BenchHarness) {
+        let mut deq = RingBuf::new();
+        b.iter(|| {
+            for _ in range(0, 65) {
+                deq.push_front(1);
+            }
+        })
+    }
+
+    #[deriving(Clone, Eq)]
+    enum Taggy {
+        One(int),
+        Two(int, int),
+        Three(int, int, int),
+    }
+
+    #[deriving(Clone, Eq)]
+    enum Taggypar<T> {
+        Onepar(int),
+        Twopar(int, int),
+        Threepar(int, int, int),
+    }
+
+    #[deriving(Clone, Eq)]
+    struct RecCy {
+        x: int,
+        y: int,
+        t: Taggy
+    }
+
+    #[test]
+    fn test_param_int() {
+        test_parameterized::<int>(5, 72, 64, 175);
+    }
+
+    #[test]
+    fn test_param_at_int() {
+        test_parameterized::<@int>(@5, @72, @64, @175);
+    }
+
+    #[test]
+    fn test_param_taggy() {
+        test_parameterized::<Taggy>(One(1), Two(1, 2), Three(1, 2, 3), Two(17, 42));
+    }
+
+    #[test]
+    fn test_param_taggypar() {
+        test_parameterized::<Taggypar<int>>(Onepar::<int>(1),
+                                            Twopar::<int>(1, 2),
+                                            Threepar::<int>(1, 2, 3),
+                                            Twopar::<int>(17, 42));
+    }
+
+    #[test]
+    fn test_param_reccy() {
+        let reccy1 = RecCy { x: 1, y: 2, t: One(1) };
+        let reccy2 = RecCy { x: 345, y: 2, t: Two(1, 2) };
+        let reccy3 = RecCy { x: 1, y: 777, t: Three(1, 2, 3) };
+        let reccy4 = RecCy { x: 19, y: 252, t: Two(17, 42) };
+        test_parameterized::<RecCy>(reccy1, reccy2, reccy3, reccy4);
+    }
+
+    #[test]
+    fn test_with_capacity() {
+        let mut d = RingBuf::with_capacity(0);
+        d.push_back(1);
+        assert_eq!(d.len(), 1);
+        let mut d = RingBuf::with_capacity(50);
+        d.push_back(1);
+        assert_eq!(d.len(), 1);
+    }
+
+    #[test]
+    fn test_reserve_exact() {
+        let mut d = RingBuf::new();
+        d.push_back(0u64);
+        d.reserve_exact(50);
+        assert_eq!(d.elts.capacity(), 50);
+        let mut d = RingBuf::new();
+        d.push_back(0u32);
+        d.reserve_exact(50);
+        assert_eq!(d.elts.capacity(), 50);
+    }
+
+    #[test]
+    fn test_reserve() {
+        let mut d = RingBuf::new();
+        d.push_back(0u64);
+        d.reserve(50);
+        assert_eq!(d.elts.capacity(), 64);
+        let mut d = RingBuf::new();
+        d.push_back(0u32);
+        d.reserve(50);
+        assert_eq!(d.elts.capacity(), 64);
+    }
+
+    #[test]
+    fn test_swap() {
+        let mut d: RingBuf<int> = range(0, 5).collect();
+        d.pop_front();
+        d.swap(0, 3);
+        assert_eq!(d.iter().map(|&x|x).collect::<~[int]>(), ~[4, 2, 3, 1]);
+    }
+
+    #[test]
+    fn test_iter() {
+        let mut d = RingBuf::new();
+        assert_eq!(d.iter().next(), None);
+        assert_eq!(d.iter().size_hint(), (0, Some(0)));
+
+        for i in range(0, 5) {
+            d.push_back(i);
+        }
+        assert_eq!(d.iter().collect::<~[&int]>(), ~[&0,&1,&2,&3,&4]);
+
+        for i in range(6, 9) {
+            d.push_front(i);
+        }
+        assert_eq!(d.iter().collect::<~[&int]>(), ~[&8,&7,&6,&0,&1,&2,&3,&4]);
+
+        let mut it = d.iter();
+        let mut len = d.len();
+        loop {
+            match it.next() {
+                None => break,
+                _ => { len -= 1; assert_eq!(it.size_hint(), (len, Some(len))) }
+            }
+        }
+    }
+
+    #[test]
+    fn test_rev_iter() {
+        let mut d = RingBuf::new();
+        assert_eq!(d.rev_iter().next(), None);
+
+        for i in range(0, 5) {
+            d.push_back(i);
+        }
+        assert_eq!(d.rev_iter().collect::<~[&int]>(), ~[&4,&3,&2,&1,&0]);
+
+        for i in range(6, 9) {
+            d.push_front(i);
+        }
+        assert_eq!(d.rev_iter().collect::<~[&int]>(), ~[&4,&3,&2,&1,&0,&6,&7,&8]);
+    }
+
+    #[test]
+    fn test_mut_rev_iter_wrap() {
+        let mut d = RingBuf::with_capacity(3);
+        assert!(d.mut_rev_iter().next().is_none());
+
+        d.push_back(1);
+        d.push_back(2);
+        d.push_back(3);
+        assert_eq!(d.pop_front(), Some(1));
+        d.push_back(4);
+
+        assert_eq!(d.mut_rev_iter().map(|x| *x).collect::<~[int]>(),
+                   ~[4, 3, 2]);
+    }
+
+    #[test]
+    fn test_mut_iter() {
+        let mut d = RingBuf::new();
+        assert!(d.mut_iter().next().is_none());
+
+        for i in range(0u, 3) {
+            d.push_front(i);
+        }
+
+        for (i, elt) in d.mut_iter().enumerate() {
+            assert_eq!(*elt, 2 - i);
+            *elt = i;
+        }
+
+        {
+            let mut it = d.mut_iter();
+            assert_eq!(*it.next().unwrap(), 0);
+            assert_eq!(*it.next().unwrap(), 1);
+            assert_eq!(*it.next().unwrap(), 2);
+            assert!(it.next().is_none());
+        }
+    }
+
+    #[test]
+    fn test_mut_rev_iter() {
+        let mut d = RingBuf::new();
+        assert!(d.mut_rev_iter().next().is_none());
+
+        for i in range(0u, 3) {
+            d.push_front(i);
+        }
+
+        for (i, elt) in d.mut_rev_iter().enumerate() {
+            assert_eq!(*elt, i);
+            *elt = i;
+        }
+
+        {
+            let mut it = d.mut_rev_iter();
+            assert_eq!(*it.next().unwrap(), 0);
+            assert_eq!(*it.next().unwrap(), 1);
+            assert_eq!(*it.next().unwrap(), 2);
+            assert!(it.next().is_none());
+        }
+    }
+
+    #[test]
+    fn test_from_iterator() {
+        use std::iter;
+        let v = ~[1,2,3,4,5,6,7];
+        let deq: RingBuf<int> = v.iter().map(|&x| x).collect();
+        let u: ~[int] = deq.iter().map(|&x| x).collect();
+        assert_eq!(u, v);
+
+        let mut seq = iter::count(0u, 2).take(256);
+        let deq: RingBuf<uint> = seq.collect();
+        for (i, &x) in deq.iter().enumerate() {
+            assert_eq!(2*i, x);
+        }
+        assert_eq!(deq.len(), 256);
+    }
+
+    #[test]
+    fn test_clone() {
+        let mut d = RingBuf::new();
+        d.push_front(17);
+        d.push_front(42);
+        d.push_back(137);
+        d.push_back(137);
+        assert_eq!(d.len(), 4u);
+        let mut e = d.clone();
+        assert_eq!(e.len(), 4u);
+        while !d.is_empty() {
+            assert_eq!(d.pop_back(), e.pop_back());
+        }
+        assert_eq!(d.len(), 0u);
+        assert_eq!(e.len(), 0u);
+    }
+
+    #[test]
+    fn test_eq() {
+        let mut d = RingBuf::new();
+        assert_eq!(&d, &RingBuf::with_capacity(0));
+        d.push_front(137);
+        d.push_front(17);
+        d.push_front(42);
+        d.push_back(137);
+        let mut e = RingBuf::with_capacity(0);
+        e.push_back(42);
+        e.push_back(17);
+        e.push_back(137);
+        e.push_back(137);
+        assert_eq!(&e, &d);
+        e.pop_back();
+        e.push_back(0);
+        assert!(e != d);
+        e.clear();
+        assert_eq!(e, RingBuf::new());
+    }
+}