Struct immutable_chunkmap::map::Map

pub struct Map<K: Ord + Clone, V: Clone>(_);

This Map uses a similar strategy to BTreeMap to ensure cache efficient performance on modern hardware while still providing log(N) get, insert, and remove operations.

For good performance, it is very important to understand that clone is a fundamental operation, it needs to be fast for your key and data types, because it’s going to be called a lot whenever you change the map.

Why

1. Multiple threads can read this structure even while one thread is updating it. Using a library like arc_swap you can avoid ever blocking readers.

2. Snapshotting this structure is free.

Examples

use std::string::String;
use self::immutable_chunkmap::map::Map;

let m =
   Map::new()
   .insert(String::from("1"), 1).0
   .insert(String::from("2"), 2).0
   .insert(String::from("3"), 3).0;

assert_eq!(m.get("1"), Option::Some(&1));
assert_eq!(m.get("2"), Option::Some(&2));
assert_eq!(m.get("3"), Option::Some(&3));
assert_eq!(m.get("4"), Option::None);

for (k, v) in &m {
  println!("key {}, val: {}", k, v)
}

Implementations

impl<K, V> Map<K, V>where
    K: Ord + Clone,
    V: Clone,

pub fn new() -> Self

Create a new empty map

pub fn insert_many<E: IntoIterator<Item = (K, V)>>(&self, elts: E) -> Self

This will insert many elements at once, and is potentially a lot faster than inserting one by one, especially if the data is sorted. It is just a wrapper around the more general update_many method.

#Examples

 use self::immutable_chunkmap::map::Map;

 let mut v = vec![(1, 3), (10, 1), (-12, 2), (44, 0), (50, -1)];
 v.sort_unstable_by_key(|&(k, _)| k);

 let m = Map::new().insert_many(v.iter().map(|(k, v)| (*k, *v)));

 for (k, v) in &v {
   assert_eq!(m.get(k), Option::Some(v))
 }

pub fn update_many<Q, D, E, F>(&self, elts: E, f: F) -> Selfwhere
    E: IntoIterator<Item = (Q, D)>,
    Q: Ord,
    K: Borrow<Q>,
    F: FnMut(Q, D, Option<(&K, &V)>) -> Option<(K, V)>,

This method updates multiple bindings in one call. Given an iterator of an arbitrary type (Q, D), where Q is any borrowed form of K, an update function taking Q, D, the current binding in the map, if any, and producing the new binding, if any, this method will produce a new map with updated bindings of many elements at once. It will skip intermediate node allocations where possible. If the data in elts is sorted, it will be able to skip many more intermediate allocations, and can produce a speedup of about 10x compared to inserting/updating one by one. In any case it should always be faster than inserting elements one by one, even with random unsorted keys.

#Examples

use std::iter::FromIterator;
use self::immutable_chunkmap::map::Map;

let m = Map::from_iter((0..4).map(|k| (k, k)));
let m = m.update_many(
    (0..4).map(|x| (x, ())),
    |k, (), cur| cur.map(|(_, c)| (k, c + 1))
);
assert_eq!(
    m.into_iter().map(|(k, v)| (*k, *v)).collect::<Vec<_>>(),
    vec![(0, 1), (1, 2), (2, 3), (3, 4)]
);

pub fn insert(&self, k: K, v: V) -> (Self, Option<V>)

return a new map with (k, v) inserted into it. If k already exists in the old map, the old binding will be returned, and the new map will contain the new binding. In fact this method is just a wrapper around update.

pub fn update<Q, D, F>(&self, q: Q, d: D, f: F) -> (Self, Option<V>)where
    Q: Ord,
    K: Borrow<Q>,
    F: FnMut(Q, D, Option<(&K, &V)>) -> Option<(K, V)>,

return a new map with the binding for q, which can be any borrowed form of k, updated to the result of f. If f returns None, the binding will be removed from the new map, otherwise it will be inserted. This function is more efficient than calling get and then insert, since it makes only one tree traversal instead of two. This method runs in log(N) time and space where N is the size of the map.

Examples

use self::immutable_chunkmap::map::Map;

let (m, _) = Map::new().update(0, 0, |k, d, _| Some((k, d)));
let (m, _) = m.update(1, 1, |k, d, _| Some((k, d)));
let (m, _) = m.update(2, 2, |k, d, _| Some((k, d)));
assert_eq!(m.get(&0), Some(&0));
assert_eq!(m.get(&1), Some(&1));
assert_eq!(m.get(&2), Some(&2));

let (m, _) = m.update(0, (), |k, (), v| v.map(move |(_, v)| (k, v + 1)));
assert_eq!(m.get(&0), Some(&1));
assert_eq!(m.get(&1), Some(&1));
assert_eq!(m.get(&2), Some(&2));

let (m, _) = m.update(1, (), |_, (), _| None);
assert_eq!(m.get(&0), Some(&1));
assert_eq!(m.get(&1), None);
assert_eq!(m.get(&2), Some(&2));

pub fn merge<F>(&self, other: &Map<K, V>, f: F) -> Selfwhere
    F: FnMut(&K, &V, &V) -> Option<V>,

Merge two maps together. Bindings that exist in both maps will be passed to f, which may elect to remove the binding by returning None. This function runs in O(log(n) + m) time and space, where n is the size of the largest map, and m is the number of intersecting chunks. It will never be slower than calling update_many on the first map with an iterator over the second, and will be significantly faster if the intersection is minimal or empty.

Examples

use std::iter::FromIterator;
use self::immutable_chunkmap::map::Map;

let m0 = Map::from_iter((0..10).map(|k| (k, 1)));
let m1 = Map::from_iter((10..20).map(|k| (k, 1)));
let m2 = m0.merge(&m1, |_k, _v0, _v1| panic!("no intersection expected"));

for i in 0..20 {
    assert!(m2.get(&i).is_some())
}

let m3 = Map::from_iter((5..9).map(|k| (k, 1)));
let m4 = m3.merge(&m2, |_k, v0, v1| Some(v0 + v1));

for i in 0..20 {
   assert!(
       *m4.get(&i).unwrap() ==
       *m3.get(&i).unwrap_or(&0) + *m2.get(&i).unwrap_or(&0)
   )
}

pub fn intersect<F>(&self, other: &Map<K, V>, f: F) -> Selfwhere
    F: FnMut(&K, &V, &V) -> Option<V>,

Produce a map containing the intersection (by key) of two maps. The function f runs on each intersecting element, and has the option to omit elements from the intersection by returning None, or change the value any way it likes. Runs in O(log(N) + M) time and space where N is the size of the smallest map, and M is the number of intersecting chunks.

Examples

 use std::iter::FromIterator;
 use self::immutable_chunkmap::map::Map;

 let m0 = Map::from_iter((0..100000).map(|k| (k, 1)));
 let m1 = Map::from_iter((50..30000).map(|k| (k, 1)));
 m0.invariant();
 m1.invariant();
 let m2 = m0.intersect(&m1, |_k, v0, v1| Some(v0 + v1));
 m2.invariant();

 println!("{:#?}", m2);
 for i in 0..100000 {
     if i >= 30000 || i < 50 {
         assert!(m2.get(&i).is_none());
     } else {
         println!("i: {}", i);
         assert!(*m2.get(&i).unwrap() == 2);
     }
 }

pub fn get<'a, Q: ?Sized + Ord>(&'a self, k: &Q) -> Option<&'a V>where
    K: Borrow<Q>,

lookup the mapping for k. If it doesn’t exist return None. Runs in log(N) time and constant space. where N is the size of the map.

pub fn get_key<'a, Q: ?Sized + Ord>(&'a self, k: &Q) -> Option<&'a K>where
    K: Borrow<Q>,

lookup the mapping for k. Return the key. If it doesn’t exist return None. Runs in log(N) time and constant space. where N is the size of the map.

pub fn get_full<'a, Q: ?Sized + Ord>(&'a self, k: &Q) -> Option<(&'a K, &'a V)>where
    K: Borrow<Q>,

lookup the mapping for k. Return both the key and the value. If it doesn’t exist return None. Runs in log(N) time and constant space. where N is the size of the map.

pub fn remove<Q: Sized + Ord>(&self, k: &Q) -> (Self, Option<V>)where
    K: Borrow<Q>,

return a new map with the mapping under k removed. If the binding existed in the old map return it. Runs in log(N) time and log(N) space, where N is the size of the map.

pub fn len(&self) -> usize

get the number of elements in the map O(1) time and space

pub fn range<'a, Q>(
    &'a self,
    lbound: Bound<Q>,
    ubound: Bound<Q>
) -> Iter<'a, Q, K, V>where
    Q: Ord,
    K: Borrow<Q>,

return an iterator over the subset of elements in the map that are within the specified range.

The returned iterator runs in O(log(N) + M) time, and constant space. N is the number of elements in the tree, and M is the number of elements you examine.

if lbound >= ubound the returned iterator will be empty

impl<K, V> Map<K, V>where
    K: Ord + Clone + Debug,
    V: Clone + Debug,

pub fn invariant(&self)

Trait Implementations

impl<K: Clone + Ord + Clone, V: Clone + Clone> Clone for Map<K, V>

fn clone(&self) -> Map<K, V>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<K, V> Debug for Map<K, V>where
    K: Debug + Ord + Clone,
    V: Debug + Clone,

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

Formats the value using the given formatter.

impl<K, V> Default for Map<K, V>where
    K: Ord + Clone,
    V: Clone,

fn default() -> Map<K, V>

Returns the “default value” for a type.

impl<K, V> FromIterator<(K, V)> for Map<K, V>where
    K: Ord + Clone,
    V: Clone,

fn from_iter<T: IntoIterator<Item = (K, V)>>(iter: T) -> Self

Creates a value from an iterator.

impl<K, V> Hash for Map<K, V>where
    K: Hash + Ord + Clone,
    V: Hash + Clone,

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

Feeds this value into the given Hasher.

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

Feeds a slice of this type into the given Hasher.

impl<'a, Q, K, V> Index<&'a Q> for Map<K, V>where
    Q: Ord,
    K: Ord + Clone + Borrow<Q>,
    V: Clone,

type Output = V

The returned type after indexing.

fn index(&self, k: &Q) -> &V

Performs the indexing (container[index]) operation.

impl<'a, K, V> IntoIterator for &'a Map<K, V>where
    K: 'a + Borrow<K> + Ord + Clone,
    V: 'a + Clone,

type Item = (&'a K, &'a V)

The type of the elements being iterated over.

type IntoIter = Iter<'a, K, K, V>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl<K, V> Ord for Map<K, V>where
    K: Ord + Clone,
    V: Ord + Clone,

fn cmp(&self, other: &Map<K, V>) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Selfwhere
    Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Selfwhere
    Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Selfwhere
    Self: Sized + PartialOrd<Self>,

Restrict a value to a certain interval.

impl<K, V> PartialEq<Map<K, V>> for Map<K, V>where
    K: PartialEq + Ord + Clone,
    V: PartialEq + Clone,

fn eq(&self, other: &Map<K, V>) -> bool

This method tests for self and other values to be equal, and is used by ==.

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

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<K, V> PartialOrd<Map<K, V>> for Map<K, V>where
    K: Ord + Clone,
    V: PartialOrd + Clone,

fn partial_cmp(&self, other: &Map<K, V>) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

This method tests less than (for self and other) and is used by the < operator.

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

This method tests less than or equal to (for self and other) and is used by the <= operator.

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

This method tests greater than (for self and other) and is used by the > operator.

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

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl<K, V> Eq for Map<K, V>where
    K: Eq + Ord + Clone,
    V: Eq + Clone,