Struct skiplist::ordered_skiplist::OrderedSkipList

pub struct OrderedSkipList<T> {
    // some fields omitted
}

The ordered skiplist provides a way of storing elements such that they are always sorted and at the same time provides efficient way to access, insert and remove nodes. Just like SkipList, it also provides access to indices.

By default, the OrderedSkipList uses the comparison function a.partial_cmp(b).expect("Value cannot be ordered"). This allows the list to handles all types which implement Ord and PartialOrd, though it will panic if value which cannot be ordered is inserted (such as Float::nan()).

The ordered skiplist has an associated sorting function which must be well-behaved. Specifically, given some ordering function f(a, b), it must satisfy the folowing properties:

• Be well defined: f(a, b) should always return the same value
• Be anti-symmetric: f(a, b) == Greater iff f(b, a) == Less and f(a, b) == Equal == f(b, a).
• By transitive: If f(a, b) == Greater and f(b, c) == Greater then f(a, c) == Greater.

Failure to satisfy these properties can result in unexpected behaviour at best, and at worst will cause a segfault, null deref, or some other bad behaviour.

Methods

impl<T> OrderedSkipList<T> where T: PartialOrd

fn new() -> Self

Create a new skiplist with the default default comparison function of |&a, &b| a.cmp(b).unwrap() and the default number of 16 levels. As a result, any element which cannot be ordered will cause insertion to panic.

The comparison function can always be changed with sort_by, which has essentially no cost if done before inserting any elements.

Panic

The default comparison function will cause a panic if an element is inserted which cannot be ordered (such as Float::nan()).

Examples

use skiplist::OrderedSkipList;

let mut skiplist: OrderedSkipList<i64> = OrderedSkipList::new();

fn with_capacity(capacity: usize) -> Self

Constructs a new, empty skiplist with the optimal number of levels for the intended capacity. Specifically, it uses floor(log2(capacity)) number of levels, ensuring that only a few nodes occupy the highest level.

It uses the default comparison function of |&a, &b| a.cmp(b).unwrap() and can be changed with sort_by.

Panic

The default comparison function will cause a panic if an element is inserted which cannot be ordered (such as Float::nan()).

Examples

use skiplist::OrderedSkipList;

let mut skiplist = OrderedSkipList::with_capacity(100);
skiplist.extend(0..100);

impl<T> OrderedSkipList<T>

unsafe fn with_comp<F>(f: F) -> Self where F: 'static + Fn(&T, &T) -> Ordering

Create a new skiplist using the provided function in order to determine the ordering of elements within the list. It will be generated with 16 levels.

Warning

The sorting function which must be well-behaved. Specifically, given some ordering function f(a, b), it must satisfy the folowing properties:

• Be well defined: f(a, b) should always return the same value
• Be anti-symmetric: f(a, b) == Greater iff f(b, a) == Less and f(a, b) == Equal == f(b, a).
• By transitive: If f(a, b) == Greater and f(b, c) == Greater then f(a, c) == Greater.

Failure to satisfy these properties can result in unexpected behaviour at best, and at worst will cause a segfault, null deref, or some other bad behaviour.

Examples

use skiplist::OrderedSkipList;
use std::cmp::Ordering;

// Store even number before odd ones and sort as usual within same parity group.
let mut skiplist = unsafe { OrderedSkipList::with_comp(
    |a: &u64, b: &u64|
    if a%2 == b%2 {
        a.cmp(b)
    } else if a%2 == 0 {
        Ordering::Less
    } else {
        Ordering::Greater
    })};

unsafe fn sort_by<F>(&mut self, f: F) where F: 'static + Fn(&T, &T) -> Ordering

Change the method which determines the ordering of the elements in the skiplist.

Panics

This call will panic if the ordering of the elements will be changed as a result of this new comparison method.

As a result, sort_by is best to call if the skiplist is empty or has just a single element and may panic with 2 or more elements.

Warning

The sorting function which must be well-behaved. Specifically, given some ordering function f(a, b), it must satisfy the folowing properties:

• Be well defined: f(a, b) should always return the same value
• Be anti-symmetric: f(a, b) == Greater iff f(b, a) == Less and f(a, b) == Equal == f(b, a).
• By transitive: If f(a, b) == Greater and f(b, c) == Greater then f(a, c) == Greater.

Failure to satisfy these properties can result in unexpected behaviour at best, and at worst will cause a segfault, null deref, or some other bad behaviour.

Examples

use skiplist::OrderedSkipList;

let mut skiplist = OrderedSkipList::new();
unsafe { skiplist.sort_by(|a: &i64, b: &i64| b.cmp(a)) } // All good; skiplist empty.
skiplist.insert(0);                                       // Would still be good here.
skiplist.insert(10);
unsafe { skiplist.sort_by(|a: &i64, b: &i64| a.cmp(b)) } // Panics; order would change.

fn clear(&mut self)

Clears the skiplist, removing all values.

Examples

use skiplist::OrderedSkipList;

let mut skiplist = OrderedSkipList::new();
skiplist.extend(0..10);
skiplist.clear();
assert!(skiplist.is_empty());

fn len(&self) -> usize

Returns the number of elements in the skiplist.

Examples

use skiplist::OrderedSkipList;

let mut skiplist = OrderedSkipList::new();
skiplist.extend(0..10);
assert_eq!(skiplist.len(), 10);

fn is_empty(&self) -> bool

Returns true if the skiplist contains no elements.

Examples

use skiplist::OrderedSkipList;

let mut skiplist = OrderedSkipList::new();
assert!(skiplist.is_empty());

skiplist.insert(1);
assert!(!skiplist.is_empty());

fn insert(&mut self, value: T)

Insert the element into the skiplist.

Examples

use skiplist::OrderedSkipList;

let mut skiplist = OrderedSkipList::new();

skiplist.insert(0);
skiplist.insert(5);
assert_eq!(skiplist.len(), 2);
assert!(!skiplist.is_empty());

fn front(&self) -> Option<&T>

Provides a reference to the front element, or None if the skiplist is empty.

Examples

use skiplist::OrderedSkipList;

let mut skiplist = OrderedSkipList::new();
assert_eq!(skiplist.front(), None);

skiplist.insert(1);
skiplist.insert(2);
assert_eq!(skiplist.front(), Some(&1));

fn back(&self) -> Option<&T>

Provides a reference to the back element, or None if the skiplist is empty.

Examples

use skiplist::OrderedSkipList;

let mut skiplist = OrderedSkipList::new();
assert_eq!(skiplist.back(), None);

skiplist.insert(1);
skiplist.insert(2);
assert_eq!(skiplist.back(), Some(&2));

fn get(&self, index: &usize) -> Option<&T>

Provides a reference to the element at the given index, or None if the skiplist is empty or the index is out of bounds.

Examples

use skiplist::OrderedSkipList;

let mut skiplist = OrderedSkipList::new();
assert_eq!(skiplist.get(&0), None);
skiplist.extend(0..10);
assert_eq!(skiplist.get(&0), Some(&0));
assert_eq!(skiplist.get(&10), None);

fn pop_front(&mut self) -> Option<T>

Removes the first element and returns it, or None if the sequence is empty.

Examples

use skiplist::OrderedSkipList;

let mut skiplist = OrderedSkipList::new();
skiplist.insert(1);
skiplist.insert(2);

assert_eq!(skiplist.pop_front(), Some(1));
assert_eq!(skiplist.pop_front(), Some(2));
assert_eq!(skiplist.pop_front(), None);

fn pop_back(&mut self) -> Option<T>

Removes the last element and returns it, or None if the sequence is empty.

Examples

use skiplist::OrderedSkipList;

let mut skiplist = OrderedSkipList::new();
skiplist.insert(1);
skiplist.insert(2);

assert_eq!(skiplist.pop_back(), Some(2));
assert_eq!(skiplist.pop_back(), Some(1));
assert_eq!(skiplist.pop_back(), None);

fn contains(&self, value: &T) -> bool

Returns true if the value is contained in the skiplist.

Examples

use skiplist::OrderedSkipList;

let mut skiplist = OrderedSkipList::new();
skiplist.extend(0..10);
assert!(skiplist.contains(&4));
assert!(!skiplist.contains(&15));

fn remove(&mut self, value: &T) -> Option<T>

Removes and returns an element with the same value or None if there are no such values in the skiplist.

If the skiplist contains multiple values with the desired value, the highest level one will be removed. This will results in a deterioration in the skiplist's performance if the skiplist contains many duplicated values which are very frequently inserted and removed. In such circumstances, the slower remove_first method is preferred.

Examples

use skiplist::OrderedSkipList;

let mut skiplist = OrderedSkipList::new();
skiplist.extend(0..10);
assert_eq!(skiplist.remove(&4), Some(4)); // Removes the last one
assert_eq!(skiplist.remove(&4), None); // No more '4' left

fn remove_first(&mut self, value: &T) -> Option<T>

Removes and returns an element with the same value or None if there are no such values in the skiplist.

If the skiplist contains multiple values with the desired value, the first one in the skiplist will be returned. If the skiplist contains many duplicated values which are frequently inserted and removed, this method should be preferred over remove.

Examples

use skiplist::OrderedSkipList;

let mut skiplist = OrderedSkipList::new();
for _ in 0..10 {
    skiplist.extend(0..10);
}
assert_eq!(skiplist.remove(&15), None);
for _ in 0..9 {
    for i in 0..10 {
        skiplist.remove_first(&i);
    }
}
assert_eq!(skiplist.remove_first(&4), Some(4)); // Removes the last one
assert_eq!(skiplist.remove_first(&4), None); // No more '4' left

fn remove_index(&mut self, index: &usize) -> T

Removes and returns an element with the given index.

Panics

Panics is the index is out of bounds.

Examples

use skiplist::OrderedSkipList;

let mut skiplist = OrderedSkipList::new();
skiplist.extend(0..10);
assert_eq!(skiplist.remove_index(&4), 4);
assert_eq!(skiplist.remove_index(&4), 5);

fn retain<F>(&mut self, f: F) where F: FnMut(&T) -> bool

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.

Examples

use skiplist::OrderedSkipList;

let mut skiplist = OrderedSkipList::new();
skiplist.extend(0..10);
skiplist.retain(|&x| x%2 == 0);

fn dedup(&mut self)

Removes all repeated elements in the skiplist using the skiplist's comparison function.

Examples

use skiplist::OrderedSkipList;

let mut skiplist = OrderedSkipList::new();
skiplist.extend(0..5);
skiplist.insert(3);
skiplist.dedup();

fn into_iter(self) -> IntoIter<T>

Get an owning iterator over the entries of the skiplist.

Examples

use skiplist::OrderedSkipList;

let mut skiplist = OrderedSkipList::new();
skiplist.extend(0..10);
for i in skiplist.into_iter() {
    println!("Value: {}", i);
}

fn iter(&self) -> Iter<T>

Creates an iterator over the entries of the skiplist.

Examples

use skiplist::OrderedSkipList;

let mut skiplist = OrderedSkipList::new();
skiplist.extend(0..10);
for i in skiplist.iter() {
    println!("Value: {}", i);
}

fn range(&self, min: Bound<&T>, max: Bound<&T>) -> Iter<T>

Constructs a double-ended iterator over a sub-range of elements in the skiplist, starting at min, and ending at max. If min is Unbounded, then it will be treated as "negative infinity", and if max is Unbounded, then it will be treated as "positive infinity". Thus range(Unbounded, Unbounded) will yield the whole collection.

Examples

#![feature(collections_bound)]
use skiplist::OrderedSkipList;
use std::collections::Bound::{Included, Unbounded};

let mut skiplist = OrderedSkipList::new();
skiplist.extend(0..10);
for i in skiplist.range(Included(&3), Included(&7)) {
    println!("Value: {}", i);
}
assert_eq!(Some(&4), skiplist.range(Included(&4), Unbounded).next());

Trait Implementations

impl<T: Send> Send for OrderedSkipList<T>

impl<T: Sync> Sync for OrderedSkipList<T>

impl<T> Drop for OrderedSkipList<T>

fn drop(&mut self)

impl<T: PartialOrd> Default for OrderedSkipList<T>

fn default() -> OrderedSkipList<T>

impl<A, B> PartialEq<OrderedSkipList<B>> for OrderedSkipList<A> where A: PartialEq<B>

This implementation of PartialEq only checks that the values are equal; it does not check for equivalence of other features (such as the ordering function and the node levels). Furthermore, this uses T's implementation of PartialEq and does not use the owning skiplist's comparison function.

fn eq(&self, other: &OrderedSkipList<B>) -> bool

fn ne(&self, other: &OrderedSkipList<B>) -> bool

impl<T> Eq for OrderedSkipList<T> where T: Eq

impl<A, B> PartialOrd<OrderedSkipList<B>> for OrderedSkipList<A> where A: PartialOrd<B>

fn partial_cmp(&self, other: &OrderedSkipList<B>) -> Option<Ordering>

fn lt(&self, other: &Rhs) -> bool

fn le(&self, other: &Rhs) -> bool

fn gt(&self, other: &Rhs) -> bool

fn ge(&self, other: &Rhs) -> bool

impl<T> Ord for OrderedSkipList<T> where T: Ord

fn cmp(&self, other: &OrderedSkipList<T>) -> Ordering

impl<T> Extend<T> for OrderedSkipList<T>

fn extend<I: IntoIterator<Item=T>>(&mut self, iterable: I)

impl<T> Index<usize> for OrderedSkipList<T>

type Output = T

fn index(&self, index: usize) -> &T

impl<T> Debug for OrderedSkipList<T> where T: Debug

fn fmt(&self, f: &mut Formatter) -> Result

impl<T> Display for OrderedSkipList<T> where T: Display

fn fmt(&self, f: &mut Formatter) -> Result

impl<T> IntoIterator for OrderedSkipList<T>

type Item = T

type IntoIter = IntoIter<T>

fn into_iter(self) -> IntoIter<T>

impl<'a, T> IntoIterator for &'a OrderedSkipList<T>

type Item = &'a T

type IntoIter = Iter<'a, T>

fn into_iter(self) -> Iter<'a, T>

impl<'a, T> IntoIterator for &'a mut OrderedSkipList<T>

type Item = &'a T

type IntoIter = Iter<'a, T>

fn into_iter(self) -> Iter<'a, T>

impl<T> FromIterator<T> for OrderedSkipList<T> where T: PartialOrd

fn from_iter<I>(iter: I) -> OrderedSkipList<T> where I: IntoIterator<Item=T>

impl<T: Hash> Hash for OrderedSkipList<T>

fn hash<H: Hasher>(&self, state: &mut H)

fn hash_slice<H>(data: &[Self], state: &mut H) where H: Hasher