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rust/src/libstd/hashmap.rs
Alex Crichton 359ac360a4 Register new snapshots 
This enables the parser error for `extern mod` => `extern crate` transitions.
2014-02-14 22:55:20 -08:00

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// Copyright 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.
//! Unordered containers, implemented as hash-tables (`HashSet` and `HashMap` types)
//!
//! The tables use a keyed hash with new random keys generated for each container, so the ordering
//! of a set of keys in a hash table is randomized.
//!
//! # Example
//!
//! ```rust
//! use std::hashmap::HashMap;
//!
//! // type inference lets us omit an explicit type signature (which
//! // would be `HashMap<&str, &str>` in this example).
//! let mut book_reviews = HashMap::new();
//!
//! // review some books.
//! book_reviews.insert("Adventures of Hucklebury Fin", "My favorite book.");
//! book_reviews.insert("Grimms' Fairy Tales", "Masterpiece.");
//! book_reviews.insert("Pride and Prejudice", "Very enjoyable.");
//! book_reviews.insert("The Adventures of Sherlock Holmes", "Eye lyked it alot.");
//!
//! // check for a specific one.
//! if !book_reviews.contains_key(& &"Les Misérables") {
//! println!("We've got {} reviews, but Les Misérables ain't one.",
//! book_reviews.len());
//! }
//!
//! // oops, this review has a lot of spelling mistakes, let's delete it.
//! book_reviews.remove(& &"The Adventures of Sherlock Holmes");
//!
//! // look up the values associated with some keys.
//! let to_find = ["Pride and Prejudice", "Alice's Adventure in Wonderland"];
//! for book in to_find.iter() {
//! match book_reviews.find(book) {
//! Some(review) => println!("{}: {}", *book, *review),
//! None => println!("{} is unreviewed.", *book)
//! }
//! }
//!
//! // iterate over everything.
//! for (book, review) in book_reviews.iter() {
//! println!("{}: \"{}\"", *book, *review);
//! }
//! ```
use container::{Container, Mutable, Map, MutableMap, Set, MutableSet};
use clone::Clone;
use cmp::{Eq, Equiv, max};
use default::Default;
use fmt;
use hash::Hash;
use iter;
use iter::{Iterator, FromIterator, Extendable};
use iter::{FilterMap, Chain, Repeat, Zip};
use mem::replace;
use num;
use option::{None, Option, Some};
use rand::Rng;
use rand;
use result::{Ok, Err};
use vec::{ImmutableVector, MutableVector, OwnedVector, Items, MutItems};
use vec_ng;
use vec_ng::Vec;
static INITIAL_CAPACITY: uint = 32u; // 2^5
struct Bucket<K,V> {
hash: uint,
key: K,
value: V,
}
/// A hash map implementation which uses linear probing along with the SipHash
/// hash function for internal state. This means that the order of all hash maps
/// is randomized by keying each hash map randomly on creation.
///
/// It is required that the keys implement the `Eq` and `Hash` traits, although
/// this can frequently be achieved by just implementing the `Eq` and
/// `IterBytes` traits as `Hash` is automatically implemented for types that
/// implement `IterBytes`.
pub struct HashMap<K,V> {
priv k0: u64,
priv k1: u64,
priv resize_at: uint,
priv size: uint,
priv buckets: Vec<Option<Bucket<K, V>>>
}
// We could rewrite FoundEntry to have type Option<&Bucket<K, V>>
// which would be nifty
enum SearchResult {
FoundEntry(uint), FoundHole(uint), TableFull
}
#[inline]
fn resize_at(capacity: uint) -> uint {
(capacity * 3) / 4
}
impl<K:Hash + Eq,V> HashMap<K, V> {
#[inline]
fn to_bucket(&self, h: uint) -> uint {
// A good hash function with entropy spread over all of the
// bits is assumed. SipHash is more than good enough.
h % self.buckets.len()
}
#[inline]
fn next_bucket(&self, idx: uint, len_buckets: uint) -> uint {
(idx + 1) % len_buckets
}
#[inline]
fn bucket_sequence(&self, hash: uint, op: |uint| -> bool) -> bool {
let start_idx = self.to_bucket(hash);
let len_buckets = self.buckets.len();
let mut idx = start_idx;
loop {
if !op(idx) { return false; }
idx = self.next_bucket(idx, len_buckets);
if idx == start_idx {
return true;
}
}
}
#[inline]
fn bucket_for_key(&self, k: &K) -> SearchResult {
let hash = k.hash_keyed(self.k0, self.k1) as uint;
self.bucket_for_key_with_hash(hash, k)
}
#[inline]
fn bucket_for_key_equiv<Q:Hash + Equiv<K>>(&self, k: &Q)
-> SearchResult {
let hash = k.hash_keyed(self.k0, self.k1) as uint;
self.bucket_for_key_with_hash_equiv(hash, k)
}
#[inline]
fn bucket_for_key_with_hash(&self,
hash: uint,
k: &K)
-> SearchResult {
let mut ret = TableFull;
self.bucket_sequence(hash, |i| {
match self.buckets.as_slice()[i] {
Some(ref bkt) if bkt.hash == hash && *k == bkt.key => {
ret = FoundEntry(i); false
},
None => { ret = FoundHole(i); false }
_ => true,
}
});
ret
}
#[inline]
fn bucket_for_key_with_hash_equiv<Q:Equiv<K>>(&self,
hash: uint,
k: &Q)
-> SearchResult {
let mut ret = TableFull;
self.bucket_sequence(hash, |i| {
match self.buckets.as_slice()[i] {
Some(ref bkt) if bkt.hash == hash && k.equiv(&bkt.key) => {
ret = FoundEntry(i); false
},
None => { ret = FoundHole(i); false }
_ => true,
}
});
ret
}
/// Expand the capacity of the array to the next power of two
/// and re-insert each of the existing buckets.
#[inline]
fn expand(&mut self) {
let new_capacity = self.buckets.len() * 2;
self.resize(new_capacity);
}
/// Expands the capacity of the array and re-insert each of the
/// existing buckets.
fn resize(&mut self, new_capacity: uint) {
self.resize_at = resize_at(new_capacity);
let old_buckets = replace(&mut self.buckets,
Vec::from_fn(new_capacity, |_| None));
self.size = 0;
for bucket in old_buckets.move_iter() {
self.insert_opt_bucket(bucket);
}
}
fn insert_opt_bucket(&mut self, bucket: Option<Bucket<K, V>>) {
match bucket {
Some(Bucket{hash: hash, key: key, value: value}) => {
self.insert_internal(hash, key, value);
}
None => {}
}
}
#[inline]
fn value_for_bucket<'a>(&'a self, idx: uint) -> &'a V {
match self.buckets.as_slice()[idx] {
Some(ref bkt) => &bkt.value,
None => fail!("HashMap::find: internal logic error"),
}
}
#[inline]
fn mut_value_for_bucket<'a>(&'a mut self, idx: uint) -> &'a mut V {
match self.buckets.as_mut_slice()[idx] {
Some(ref mut bkt) => &mut bkt.value,
None => unreachable!()
}
}
/// Inserts the key value pair into the buckets.
/// Assumes that there will be a bucket.
/// True if there was no previous entry with that key
fn insert_internal(&mut self, hash: uint, k: K, v: V) -> Option<V> {
match self.bucket_for_key_with_hash(hash, &k) {
TableFull => { fail!("Internal logic error"); }
FoundHole(idx) => {
self.buckets.as_mut_slice()[idx] = Some(Bucket{hash: hash, key: k, value: v});
self.size += 1;
None
}
FoundEntry(idx) => {
match self.buckets.as_mut_slice()[idx] {
None => { fail!("insert_internal: Internal logic error") }
Some(ref mut b) => {
b.hash = hash;
b.key = k;
Some(replace(&mut b.value, v))
}
}
}
}
}
fn pop_internal(&mut self, hash: uint, k: &K) -> Option<V> {
// Removing from an open-addressed hashtable
// is, well, painful. The problem is that
// the entry may lie on the probe path for other
// entries, so removing it would make you think that
// those probe paths are empty.
//
// To address this we basically have to keep walking,
// re-inserting entries we find until we reach an empty
// bucket. We know we will eventually reach one because
// we insert one ourselves at the beginning (the removed
// entry).
//
// I found this explanation elucidating:
// http://www.maths.lse.ac.uk/Courses/MA407/del-hash.pdf
let mut idx = match self.bucket_for_key_with_hash(hash, k) {
TableFull | FoundHole(_) => return None,
FoundEntry(idx) => idx
};
let len_buckets = self.buckets.len();
let bucket = self.buckets.as_mut_slice()[idx].take();
let value = bucket.map(|bucket| bucket.value);
/* re-inserting buckets may cause changes in size, so remember
what our new size is ahead of time before we start insertions */
let size = self.size - 1;
idx = self.next_bucket(idx, len_buckets);
while self.buckets.as_slice()[idx].is_some() {
let bucket = self.buckets.as_mut_slice()[idx].take();
self.insert_opt_bucket(bucket);
idx = self.next_bucket(idx, len_buckets);
}
self.size = size;
value
}
}
impl<K:Hash + Eq,V> Container for HashMap<K, V> {
/// Return the number of elements in the map
fn len(&self) -> uint { self.size }
}
impl<K:Hash + Eq,V> Mutable for HashMap<K, V> {
/// Clear the map, removing all key-value pairs.
fn clear(&mut self) {
for bkt in self.buckets.as_mut_slice().mut_iter() {
*bkt = None;
}
self.size = 0;
}
}
impl<K:Hash + Eq,V> Map<K, V> for HashMap<K, V> {
/// Return a reference to the value corresponding to the key
fn find<'a>(&'a self, k: &K) -> Option<&'a V> {
match self.bucket_for_key(k) {
FoundEntry(idx) => Some(self.value_for_bucket(idx)),
TableFull | FoundHole(_) => None,
}
}
}
impl<K:Hash + Eq,V> MutableMap<K, V> for HashMap<K, V> {
/// Return a mutable reference to the value corresponding to the key
fn find_mut<'a>(&'a mut self, k: &K) -> Option<&'a mut V> {
let idx = match self.bucket_for_key(k) {
FoundEntry(idx) => idx,
TableFull | FoundHole(_) => return None
};
Some(self.mut_value_for_bucket(idx))
}
/// Insert a key-value pair from the map. If the key already had a value
/// present in the map, that value is returned. Otherwise None is returned.
fn swap(&mut self, k: K, v: V) -> Option<V> {
// this could be faster.
if self.size >= self.resize_at {
// n.b.: We could also do this after searching, so
// that we do not resize if this call to insert is
// simply going to update a key in place. My sense
// though is that it's worse to have to search through
// buckets to find the right spot twice than to just
// resize in this corner case.
self.expand();
}
let hash = k.hash_keyed(self.k0, self.k1) as uint;
self.insert_internal(hash, k, v)
}
/// Removes a key from the map, returning the value at the key if the key
/// was previously in the map.
fn pop(&mut self, k: &K) -> Option<V> {
let hash = k.hash_keyed(self.k0, self.k1) as uint;
self.pop_internal(hash, k)
}
}
impl<K: Hash + Eq, V> HashMap<K, V> {
/// Create an empty HashMap
pub fn new() -> HashMap<K, V> {
HashMap::with_capacity(INITIAL_CAPACITY)
}
/// Create an empty HashMap with space for at least `capacity`
/// elements in the hash table.
pub fn with_capacity(capacity: uint) -> HashMap<K, V> {
let mut r = rand::task_rng();
HashMap::with_capacity_and_keys(r.gen(), r.gen(), capacity)
}
/// Create an empty HashMap with space for at least `capacity`
/// elements, using `k0` and `k1` as the keys.
///
/// Warning: `k0` and `k1` are normally randomly generated, and
/// are designed to allow HashMaps to be resistant to attacks that
/// cause many collisions and very poor performance. Setting them
/// manually using this function can expose a DoS attack vector.
pub fn with_capacity_and_keys(k0: u64, k1: u64, capacity: uint) -> HashMap<K, V> {
let cap = max(INITIAL_CAPACITY, capacity);
HashMap {
k0: k0, k1: k1,
resize_at: resize_at(cap),
size: 0,
buckets: Vec::from_fn(cap, |_| None)
}
}
/// Reserve space for at least `n` elements in the hash table.
pub fn reserve(&mut self, n: uint) {
if n > self.buckets.len() {
let buckets = n * 4 / 3 + 1;
self.resize(num::next_power_of_two(buckets));
}
}
/// Modify and return the value corresponding to the key in the map, or
/// insert and return a new value if it doesn't exist.
///
/// This method allows for all insertion behaviours of a hashmap,
/// see methods like `insert`, `find_or_insert` and
/// `insert_or_update_with` for less general and more friendly
/// variations of this.
///
/// # Example
///
/// ```rust
/// use std::hashmap::HashMap;
///
/// // map some strings to vectors of strings
/// let mut map = HashMap::<~str, ~[~str]>::new();
/// map.insert(~"a key", ~[~"value"]);
/// map.insert(~"z key", ~[~"value"]);
///
/// let new = ~[~"a key", ~"b key", ~"z key"];
/// for k in new.move_iter() {
/// map.mangle(k, ~"new value",
/// // if the key doesn't exist in the map yet, add it in
/// // the obvious way.
/// |_k, v| ~[v],
/// // if the key does exist either prepend or append this
/// // new value based on the first letter of the key.
/// |key, already, new| {
/// if key.starts_with("z") {
/// already.unshift(new);
/// } else {
/// already.push(new);
/// }
/// });
/// }
///
/// for (k, v) in map.iter() {
/// println!("{} -> {:?}", *k, *v);
/// }
/// ```
pub fn mangle<'a,
A>(
&'a mut self,
k: K,
a: A,
not_found: |&K, A| -> V,
found: |&K, &mut V, A|)
-> &'a mut V {
if self.size >= self.resize_at {
// n.b.: We could also do this after searching, so
// that we do not resize if this call to insert is
// simply going to update a key in place. My sense
// though is that it's worse to have to search through
// buckets to find the right spot twice than to just
// resize in this corner case.
self.expand();
}
let hash = k.hash_keyed(self.k0, self.k1) as uint;
let idx = match self.bucket_for_key_with_hash(hash, &k) {
TableFull => fail!("Internal logic error"),
FoundEntry(idx) => { found(&k, self.mut_value_for_bucket(idx), a); idx }
FoundHole(idx) => {
let v = not_found(&k, a);
self.buckets.as_mut_slice()[idx] = Some(Bucket{hash: hash, key: k, value: v});
self.size += 1;
idx
}
};
self.mut_value_for_bucket(idx)
}
/// Return the value corresponding to the key in the map, or insert
/// and return the value if it doesn't exist.
pub fn find_or_insert<'a>(&'a mut self, k: K, v: V) -> &'a mut V {
self.mangle(k, v, |_k, a| a, |_k,_v,_a| ())
}
/// Return the value corresponding to the key in the map, or create,
/// insert, and return a new value if it doesn't exist.
pub fn find_or_insert_with<'a>(&'a mut self, k: K, f: |&K| -> V)
-> &'a mut V {
self.mangle(k, (), |k,_a| f(k), |_k,_v,_a| ())
}
/// Insert a key-value pair into the map if the key is not already present.
/// Otherwise, modify the existing value for the key.
/// Returns the new or modified value for the key.
pub fn insert_or_update_with<'a>(
&'a mut self,
k: K,
v: V,
f: |&K, &mut V|)
-> &'a mut V {
self.mangle(k, v, |_k,a| a, |k,v,_a| f(k,v))
}
/// Retrieves a value for the given key, failing if the key is not
/// present.
pub fn get<'a>(&'a self, k: &K) -> &'a V {
match self.find(k) {
Some(v) => v,
None => fail!("No entry found for key: {:?}", k),
}
}
/// Retrieves a (mutable) value for the given key, failing if the key
/// is not present.
pub fn get_mut<'a>(&'a mut self, k: &K) -> &'a mut V {
match self.find_mut(k) {
Some(v) => v,
None => fail!("No entry found for key: {:?}", k),
}
}
/// Return true if the map contains a value for the specified key,
/// using equivalence
pub fn contains_key_equiv<Q:Hash + Equiv<K>>(&self, key: &Q) -> bool {
match self.bucket_for_key_equiv(key) {
FoundEntry(_) => {true}
TableFull | FoundHole(_) => {false}
}
}
/// Return the value corresponding to the key in the map, using
/// equivalence
pub fn find_equiv<'a, Q:Hash + Equiv<K>>(&'a self, k: &Q)
-> Option<&'a V> {
match self.bucket_for_key_equiv(k) {
FoundEntry(idx) => Some(self.value_for_bucket(idx)),
TableFull | FoundHole(_) => None,
}
}
/// An iterator visiting all keys in arbitrary order.
/// Iterator element type is &'a K.
pub fn keys<'a>(&'a self) -> Keys<'a, K, V> {
self.iter().map(|(k, _v)| k)
}
/// An iterator visiting all values in arbitrary order.
/// Iterator element type is &'a V.
pub fn values<'a>(&'a self) -> Values<'a, K, V> {
self.iter().map(|(_k, v)| v)
}
/// An iterator visiting all key-value pairs in arbitrary order.
/// Iterator element type is (&'a K, &'a V).
pub fn iter<'a>(&'a self) -> Entries<'a, K, V> {
Entries { iter: self.buckets.as_slice().iter() }
}
/// An iterator visiting all key-value pairs in arbitrary order,
/// with mutable references to the values.
/// Iterator element type is (&'a K, &'a mut V).
pub fn mut_iter<'a>(&'a mut self) -> MutEntries<'a, K, V> {
MutEntries { iter: self.buckets.as_mut_slice().mut_iter() }
}
/// Creates a consuming iterator, that is, one that moves each key-value
/// pair out of the map in arbitrary order. The map cannot be used after
/// calling this.
pub fn move_iter(self) -> MoveEntries<K, V> {
MoveEntries {iter: self.buckets.move_iter()}
}
}
impl<K: Hash + Eq, V: Clone> HashMap<K, V> {
/// Like `find`, but returns a copy of the value.
pub fn find_copy(&self, k: &K) -> Option<V> {
self.find(k).map(|v| (*v).clone())
}
/// Like `get`, but returns a copy of the value.
pub fn get_copy(&self, k: &K) -> V {
(*self.get(k)).clone()
}
}
impl<K:Hash + Eq,V:Eq> Eq for HashMap<K, V> {
fn eq(&self, other: &HashMap<K, V>) -> bool {
if self.len() != other.len() { return false; }
self.iter().all(|(key, value)| {
match other.find(key) {
None => false,
Some(v) => value == v
}
})
}
fn ne(&self, other: &HashMap<K, V>) -> bool { !self.eq(other) }
}
impl<K:Hash + Eq + Clone,V:Clone> Clone for HashMap<K,V> {
fn clone(&self) -> HashMap<K,V> {
let mut new_map = HashMap::with_capacity(self.len());
for (key, value) in self.iter() {
new_map.insert((*key).clone(), (*value).clone());
}
new_map
}
}
impl<A: fmt::Show + Hash + Eq, B: fmt::Show> fmt::Show for HashMap<A, B> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
if_ok!(write!(f.buf, r"\{"))
let mut first = true;
for (key, value) in self.iter() {
if first {
first = false;
} else {
if_ok!(write!(f.buf, ", "));
}
if_ok!(write!(f.buf, "{}: {}", *key, *value));
}
write!(f.buf, r"\}")
}
}
/// HashMap iterator
#[deriving(Clone)]
pub struct Entries<'a, K, V> {
priv iter: Items<'a, Option<Bucket<K, V>>>,
}
/// HashMap mutable values iterator
pub struct MutEntries<'a, K, V> {
priv iter: MutItems<'a, Option<Bucket<K, V>>>,
}
/// HashMap move iterator
pub struct MoveEntries<K, V> {
priv iter: vec_ng::MoveItems<Option<Bucket<K, V>>>,
}
/// HashMap keys iterator
pub type Keys<'a, K, V> =
iter::Map<'static, (&'a K, &'a V), &'a K, Entries<'a, K, V>>;
/// HashMap values iterator
pub type Values<'a, K, V> =
iter::Map<'static, (&'a K, &'a V), &'a V, Entries<'a, K, V>>;
/// HashSet iterator
#[deriving(Clone)]
pub struct SetItems<'a, K> {
priv iter: Items<'a, Option<Bucket<K, ()>>>,
}
/// HashSet move iterator
pub struct SetMoveItems<K> {
priv iter: vec_ng::MoveItems<Option<Bucket<K, ()>>>,
}
impl<'a, K, V> Iterator<(&'a K, &'a V)> for Entries<'a, K, V> {
#[inline]
fn next(&mut self) -> Option<(&'a K, &'a V)> {
for elt in self.iter {
match elt {
&Some(ref bucket) => return Some((&bucket.key, &bucket.value)),
&None => {},
}
}
None
}
}
impl<'a, K, V> Iterator<(&'a K, &'a mut V)> for MutEntries<'a, K, V> {
#[inline]
fn next(&mut self) -> Option<(&'a K, &'a mut V)> {
for elt in self.iter {
match elt {
&Some(ref mut bucket) => return Some((&bucket.key, &mut bucket.value)),
&None => {},
}
}
None
}
}
impl<K, V> Iterator<(K, V)> for MoveEntries<K, V> {
#[inline]
fn next(&mut self) -> Option<(K, V)> {
for elt in self.iter {
match elt {
Some(Bucket {key, value, ..}) => return Some((key, value)),
None => {},
}
}
None
}
}
impl<'a, K> Iterator<&'a K> for SetItems<'a, K> {
#[inline]
fn next(&mut self) -> Option<&'a K> {
for elt in self.iter {
match elt {
&Some(ref bucket) => return Some(&bucket.key),
&None => {},
}
}
None
}
}
impl<K> Iterator<K> for SetMoveItems<K> {
#[inline]
fn next(&mut self) -> Option<K> {
for elt in self.iter {
match elt {
Some(bucket) => return Some(bucket.key),
None => {},
}
}
None
}
}
impl<K: Eq + Hash, V> FromIterator<(K, V)> for HashMap<K, V> {
fn from_iterator<T: Iterator<(K, V)>>(iter: &mut T) -> HashMap<K, V> {
let (lower, _) = iter.size_hint();
let mut map = HashMap::with_capacity(lower);
map.extend(iter);
map
}
}
impl<K: Eq + Hash, V> Extendable<(K, V)> for HashMap<K, V> {
fn extend<T: Iterator<(K, V)>>(&mut self, iter: &mut T) {
for (k, v) in *iter {
self.insert(k, v);
}
}
}
impl<K: Eq + Hash, V> Default for HashMap<K, V> {
fn default() -> HashMap<K, V> { HashMap::new() }
}
/// An implementation of a hash set using the underlying representation of a
/// HashMap where the value is (). As with the `HashMap` type, a `HashSet`
/// requires that the elements implement the `Eq` and `Hash` traits.
pub struct HashSet<T> {
priv map: HashMap<T, ()>
}
impl<T:Hash + Eq> Eq for HashSet<T> {
fn eq(&self, other: &HashSet<T>) -> bool { self.map == other.map }
fn ne(&self, other: &HashSet<T>) -> bool { self.map != other.map }
}
impl<T:Hash + Eq> Container for HashSet<T> {
/// Return the number of elements in the set
fn len(&self) -> uint { self.map.len() }
}
impl<T:Hash + Eq> Mutable for HashSet<T> {
/// Clear the set, removing all values.
fn clear(&mut self) { self.map.clear() }
}
impl<T:Hash + Eq> Set<T> for HashSet<T> {
/// Return true if the set contains a value
fn contains(&self, value: &T) -> bool { self.map.contains_key(value) }
/// Return true if the set has no elements in common with `other`.
/// This is equivalent to checking for an empty intersection.
fn is_disjoint(&self, other: &HashSet<T>) -> bool {
self.iter().all(|v| !other.contains(v))
}
/// Return true if the set is a subset of another
fn is_subset(&self, other: &HashSet<T>) -> bool {
self.iter().all(|v| other.contains(v))
}
/// Return true if the set is a superset of another
fn is_superset(&self, other: &HashSet<T>) -> bool {
other.is_subset(self)
}
}
impl<T:Hash + Eq> MutableSet<T> for HashSet<T> {
/// Add a value to the set. Return true if the value was not already
/// present in the set.
fn insert(&mut self, value: T) -> bool { self.map.insert(value, ()) }
/// Remove a value from the set. Return true if the value was
/// present in the set.
fn remove(&mut self, value: &T) -> bool { self.map.remove(value) }
}
impl<T:Hash + Eq> HashSet<T> {
/// Create an empty HashSet
pub fn new() -> HashSet<T> {
HashSet::with_capacity(INITIAL_CAPACITY)
}
/// Create an empty HashSet with space for at least `n` elements in
/// the hash table.
pub fn with_capacity(capacity: uint) -> HashSet<T> {
HashSet { map: HashMap::with_capacity(capacity) }
}
/// Create an empty HashSet with space for at least `capacity`
/// elements in the hash table, using `k0` and `k1` as the keys.
///
/// Warning: `k0` and `k1` are normally randomly generated, and
/// are designed to allow HashSets to be resistant to attacks that
/// cause many collisions and very poor performance. Setting them
/// manually using this function can expose a DoS attack vector.
pub fn with_capacity_and_keys(k0: u64, k1: u64, capacity: uint) -> HashSet<T> {
HashSet { map: HashMap::with_capacity_and_keys(k0, k1, capacity) }
}
/// Reserve space for at least `n` elements in the hash table.
pub fn reserve(&mut self, n: uint) {
self.map.reserve(n)
}
/// Returns true if the hash set contains a value equivalent to the
/// given query value.
pub fn contains_equiv<Q:Hash + Equiv<T>>(&self, value: &Q) -> bool {
self.map.contains_key_equiv(value)
}
/// An iterator visiting all elements in arbitrary order.
/// Iterator element type is &'a T.
pub fn iter<'a>(&'a self) -> SetItems<'a, T> {
SetItems { iter: self.map.buckets.as_slice().iter() }
}
/// Creates a consuming iterator, that is, one that moves each value out
/// of the set in arbitrary order. The set cannot be used after calling
/// this.
pub fn move_iter(self) -> SetMoveItems<T> {
SetMoveItems {iter: self.map.buckets.move_iter()}
}
/// Visit the values representing the difference
pub fn difference<'a>(&'a self, other: &'a HashSet<T>) -> SetAlgebraItems<'a, T> {
Repeat::new(other)
.zip(self.iter())
.filter_map(|(other, elt)| {
if !other.contains(elt) { Some(elt) } else { None }
})
}
/// Visit the values representing the symmetric difference
pub fn symmetric_difference<'a>(&'a self, other: &'a HashSet<T>)
-> Chain<SetAlgebraItems<'a, T>, SetAlgebraItems<'a, T>> {
self.difference(other).chain(other.difference(self))
}
/// Visit the values representing the intersection
pub fn intersection<'a>(&'a self, other: &'a HashSet<T>)
-> SetAlgebraItems<'a, T> {
Repeat::new(other)
.zip(self.iter())
.filter_map(|(other, elt)| {
if other.contains(elt) { Some(elt) } else { None }
})
}
/// Visit the values representing the union
pub fn union<'a>(&'a self, other: &'a HashSet<T>)
-> Chain<SetItems<'a, T>, SetAlgebraItems<'a, T>> {
self.iter().chain(other.difference(self))
}
}
impl<T:Hash + Eq + Clone> Clone for HashSet<T> {
fn clone(&self) -> HashSet<T> {
HashSet {
map: self.map.clone()
}
}
}
impl<A: fmt::Show + Hash + Eq> fmt::Show for HashSet<A> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
if_ok!(write!(f.buf, r"\{"))
let mut first = true;
for x in self.iter() {
if first {
first = false;
} else {
if_ok!(write!(f.buf, ", "));
}
if_ok!(write!(f.buf, "{}", *x));
}
write!(f.buf, r"\}")
}
}
impl<K: Eq + Hash> FromIterator<K> for HashSet<K> {
fn from_iterator<T: Iterator<K>>(iter: &mut T) -> HashSet<K> {
let (lower, _) = iter.size_hint();
let mut set = HashSet::with_capacity(lower);
set.extend(iter);
set
}
}
impl<K: Eq + Hash> Extendable<K> for HashSet<K> {
fn extend<T: Iterator<K>>(&mut self, iter: &mut T) {
for k in *iter {
self.insert(k);
}
}
}
impl<K: Eq + Hash> Default for HashSet<K> {
fn default() -> HashSet<K> { HashSet::new() }
}
// `Repeat` is used to feed the filter closure an explicit capture
// of a reference to the other set
/// Set operations iterator
pub type SetAlgebraItems<'a, T> =
FilterMap<'static,(&'a HashSet<T>, &'a T), &'a T,
Zip<Repeat<&'a HashSet<T>>,SetItems<'a,T>>>;
#[cfg(test)]
mod test_map {
use prelude::*;
use super::*;
use fmt;
#[test]
fn test_create_capacity_zero() {
let mut m = HashMap::with_capacity(0);
assert!(m.insert(1, 1));
}
#[test]
fn test_insert() {
let mut m = HashMap::new();
assert!(m.insert(1, 2));
assert!(m.insert(2, 4));
assert_eq!(*m.get(&1), 2);
assert_eq!(*m.get(&2), 4);
}
#[test]
fn test_find_mut() {
let mut m = HashMap::new();
assert!(m.insert(1, 12));
assert!(m.insert(2, 8));
assert!(m.insert(5, 14));
let new = 100;
match m.find_mut(&5) {
None => fail!(), Some(x) => *x = new
}
assert_eq!(m.find(&5), Some(&new));
}
#[test]
fn test_insert_overwrite() {
let mut m = HashMap::new();
assert!(m.insert(1, 2));
assert_eq!(*m.get(&1), 2);
assert!(!m.insert(1, 3));
assert_eq!(*m.get(&1), 3);
}
#[test]
fn test_insert_conflicts() {
let mut m = HashMap::with_capacity(4);
assert!(m.insert(1, 2));
assert!(m.insert(5, 3));
assert!(m.insert(9, 4));
assert_eq!(*m.get(&9), 4);
assert_eq!(*m.get(&5), 3);
assert_eq!(*m.get(&1), 2);
}
#[test]
fn test_conflict_remove() {
let mut m = HashMap::with_capacity(4);
assert!(m.insert(1, 2));
assert!(m.insert(5, 3));
assert!(m.insert(9, 4));
assert!(m.remove(&1));
assert_eq!(*m.get(&9), 4);
assert_eq!(*m.get(&5), 3);
}
#[test]
fn test_is_empty() {
let mut m = HashMap::with_capacity(4);
assert!(m.insert(1, 2));
assert!(!m.is_empty());
assert!(m.remove(&1));
assert!(m.is_empty());
}
#[test]
fn test_pop() {
let mut m = HashMap::new();
m.insert(1, 2);
assert_eq!(m.pop(&1), Some(2));
assert_eq!(m.pop(&1), None);
}
#[test]
fn test_swap() {
let mut m = HashMap::new();
assert_eq!(m.swap(1, 2), None);
assert_eq!(m.swap(1, 3), Some(2));
assert_eq!(m.swap(1, 4), Some(3));
}
#[test]
fn test_find_or_insert() {
let mut m: HashMap<int,int> = HashMap::new();
assert_eq!(*m.find_or_insert(1, 2), 2);
assert_eq!(*m.find_or_insert(1, 3), 2);
}
#[test]
fn test_find_or_insert_with() {
let mut m: HashMap<int,int> = HashMap::new();
assert_eq!(*m.find_or_insert_with(1, |_| 2), 2);
assert_eq!(*m.find_or_insert_with(1, |_| 3), 2);
}
#[test]
fn test_insert_or_update_with() {
let mut m: HashMap<int,int> = HashMap::new();
assert_eq!(*m.insert_or_update_with(1, 2, |_,x| *x+=1), 2);
assert_eq!(*m.insert_or_update_with(1, 2, |_,x| *x+=1), 3);
}
#[test]
fn test_move_iter() {
let hm = {
let mut hm = HashMap::new();
hm.insert('a', 1);
hm.insert('b', 2);
hm
};
let v = hm.move_iter().collect::<~[(char, int)]>();
assert!([('a', 1), ('b', 2)] == v || [('b', 2), ('a', 1)] == v);
}
#[test]
fn test_iterate() {
let mut m = HashMap::with_capacity(4);
for i in range(0u, 32) {
assert!(m.insert(i, i*2));
}
let mut observed = 0;
for (k, v) in m.iter() {
assert_eq!(*v, *k * 2);
observed |= (1 << *k);
}
assert_eq!(observed, 0xFFFF_FFFF);
}
#[test]
fn test_keys() {
let vec = ~[(1, 'a'), (2, 'b'), (3, 'c')];
let map = vec.move_iter().collect::<HashMap<int, char>>();
let keys = map.keys().map(|&k| k).collect::<~[int]>();
assert_eq!(keys.len(), 3);
assert!(keys.contains(&1));
assert!(keys.contains(&2));
assert!(keys.contains(&3));
}
#[test]
fn test_values() {
let vec = ~[(1, 'a'), (2, 'b'), (3, 'c')];
let map = vec.move_iter().collect::<HashMap<int, char>>();
let values = map.values().map(|&v| v).collect::<~[char]>();
assert_eq!(values.len(), 3);
assert!(values.contains(&'a'));
assert!(values.contains(&'b'));
assert!(values.contains(&'c'));
}
#[test]
fn test_find() {
let mut m = HashMap::new();
assert!(m.find(&1).is_none());
m.insert(1, 2);
match m.find(&1) {
None => fail!(),
Some(v) => assert!(*v == 2)
}
}
#[test]
fn test_eq() {
let mut m1 = HashMap::new();
m1.insert(1, 2);
m1.insert(2, 3);
m1.insert(3, 4);
let mut m2 = HashMap::new();
m2.insert(1, 2);
m2.insert(2, 3);
assert!(m1 != m2);
m2.insert(3, 4);
assert_eq!(m1, m2);
}
#[test]
fn test_expand() {
let mut m = HashMap::new();
assert_eq!(m.len(), 0);
assert!(m.is_empty());
let mut i = 0u;
let old_resize_at = m.resize_at;
while old_resize_at == m.resize_at {
m.insert(i, i);
i += 1;
}
assert_eq!(m.len(), i);
assert!(!m.is_empty());
}
#[test]
fn test_find_equiv() {
let mut m = HashMap::new();
let (foo, bar, baz) = (1,2,3);
m.insert(~"foo", foo);
m.insert(~"bar", bar);
m.insert(~"baz", baz);
assert_eq!(m.find_equiv(&("foo")), Some(&foo));
assert_eq!(m.find_equiv(&("bar")), Some(&bar));
assert_eq!(m.find_equiv(&("baz")), Some(&baz));
assert_eq!(m.find_equiv(&("qux")), None);
}
#[test]
fn test_from_iter() {
let xs = ~[(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)];
let map: HashMap<int, int> = xs.iter().map(|&x| x).collect();
for &(k, v) in xs.iter() {
assert_eq!(map.find(&k), Some(&v));
}
}
struct ShowableStruct {
value: int,
}
impl fmt::Show for ShowableStruct {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f.buf, r"s{}", self.value)
}
}
#[test]
fn test_show() {
let mut table: HashMap<int, ShowableStruct> = HashMap::new();
let empty: HashMap<int, ShowableStruct> = HashMap::new();
table.insert(3, ShowableStruct { value: 4 });
table.insert(1, ShowableStruct { value: 2 });
let table_str = format!("{}", table);
assert!(table_str == ~"{1: s2, 3: s4}" || table_str == ~"{3: s4, 1: s2}");
assert_eq!(format!("{}", empty), ~"{}");
}
}
#[cfg(test)]
mod test_set {
use super::*;
use prelude::*;
use container::Container;
use vec::ImmutableEqVector;
#[test]
fn test_disjoint() {
let mut xs = HashSet::new();
let mut ys = HashSet::new();
assert!(xs.is_disjoint(&ys));
assert!(ys.is_disjoint(&xs));
assert!(xs.insert(5));
assert!(ys.insert(11));
assert!(xs.is_disjoint(&ys));
assert!(ys.is_disjoint(&xs));
assert!(xs.insert(7));
assert!(xs.insert(19));
assert!(xs.insert(4));
assert!(ys.insert(2));
assert!(ys.insert(-11));
assert!(xs.is_disjoint(&ys));
assert!(ys.is_disjoint(&xs));
assert!(ys.insert(7));
assert!(!xs.is_disjoint(&ys));
assert!(!ys.is_disjoint(&xs));
}
#[test]
fn test_subset_and_superset() {
let mut a = HashSet::new();
assert!(a.insert(0));
assert!(a.insert(5));
assert!(a.insert(11));
assert!(a.insert(7));
let mut b = HashSet::new();
assert!(b.insert(0));
assert!(b.insert(7));
assert!(b.insert(19));
assert!(b.insert(250));
assert!(b.insert(11));
assert!(b.insert(200));
assert!(!a.is_subset(&b));
assert!(!a.is_superset(&b));
assert!(!b.is_subset(&a));
assert!(!b.is_superset(&a));
assert!(b.insert(5));
assert!(a.is_subset(&b));
assert!(!a.is_superset(&b));
assert!(!b.is_subset(&a));
assert!(b.is_superset(&a));
}
#[test]
fn test_iterate() {
let mut a = HashSet::new();
for i in range(0u, 32) {
assert!(a.insert(i));
}
let mut observed = 0;
for k in a.iter() {
observed |= (1 << *k);
}
assert_eq!(observed, 0xFFFF_FFFF);
}
#[test]
fn test_intersection() {
let mut a = HashSet::new();
let mut b = HashSet::new();
assert!(a.insert(11));
assert!(a.insert(1));
assert!(a.insert(3));
assert!(a.insert(77));
assert!(a.insert(103));
assert!(a.insert(5));
assert!(a.insert(-5));
assert!(b.insert(2));
assert!(b.insert(11));
assert!(b.insert(77));
assert!(b.insert(-9));
assert!(b.insert(-42));
assert!(b.insert(5));
assert!(b.insert(3));
let mut i = 0;
let expected = [3, 5, 11, 77];
for x in a.intersection(&b) {
assert!(expected.contains(x));
i += 1
}
assert_eq!(i, expected.len());
}
#[test]
fn test_difference() {
let mut a = HashSet::new();
let mut b = HashSet::new();
assert!(a.insert(1));
assert!(a.insert(3));
assert!(a.insert(5));
assert!(a.insert(9));
assert!(a.insert(11));
assert!(b.insert(3));
assert!(b.insert(9));
let mut i = 0;
let expected = [1, 5, 11];
for x in a.difference(&b) {
assert!(expected.contains(x));
i += 1
}
assert_eq!(i, expected.len());
}
#[test]
fn test_symmetric_difference() {
let mut a = HashSet::new();
let mut b = HashSet::new();
assert!(a.insert(1));
assert!(a.insert(3));
assert!(a.insert(5));
assert!(a.insert(9));
assert!(a.insert(11));
assert!(b.insert(-2));
assert!(b.insert(3));
assert!(b.insert(9));
assert!(b.insert(14));
assert!(b.insert(22));
let mut i = 0;
let expected = [-2, 1, 5, 11, 14, 22];
for x in a.symmetric_difference(&b) {
assert!(expected.contains(x));
i += 1
}
assert_eq!(i, expected.len());
}
#[test]
fn test_union() {
let mut a = HashSet::new();
let mut b = HashSet::new();
assert!(a.insert(1));
assert!(a.insert(3));
assert!(a.insert(5));
assert!(a.insert(9));
assert!(a.insert(11));
assert!(a.insert(16));
assert!(a.insert(19));
assert!(a.insert(24));
assert!(b.insert(-2));
assert!(b.insert(1));
assert!(b.insert(5));
assert!(b.insert(9));
assert!(b.insert(13));
assert!(b.insert(19));
let mut i = 0;
let expected = [-2, 1, 3, 5, 9, 11, 13, 16, 19, 24];
for x in a.union(&b) {
assert!(expected.contains(x));
i += 1
}
assert_eq!(i, expected.len());
}
#[test]
fn test_from_iter() {
let xs = ~[1, 2, 3, 4, 5, 6, 7, 8, 9];
let set: HashSet<int> = xs.iter().map(|&x| x).collect();
for x in xs.iter() {
assert!(set.contains(x));
}
}
#[test]
fn test_move_iter() {
let hs = {
let mut hs = HashSet::new();
hs.insert('a');
hs.insert('b');
hs
};
let v = hs.move_iter().collect::<~[char]>();
assert!(['a', 'b'] == v || ['b', 'a'] == v);
}
#[test]
fn test_eq() {
let mut s1 = HashSet::new();
s1.insert(1);
s1.insert(2);
s1.insert(3);
let mut s2 = HashSet::new();
s2.insert(1);
s2.insert(2);
assert!(s1 != s2);
s2.insert(3);
assert_eq!(s1, s2);
}
#[test]
fn test_show() {
let mut set: HashSet<int> = HashSet::new();
let empty: HashSet<int> = HashSet::new();
set.insert(1);
set.insert(2);
let set_str = format!("{}", set);
assert!(set_str == ~"{1, 2}" || set_str == ~"{2, 1}");
assert_eq!(format!("{}", empty), ~"{}");
}
}
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