rust/src/libstd/collections/hashmap/set.rs
2014-10-25 23:11:17 -04:00

710 lines
20 KiB
Rust

// 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.
//
// ignore-lexer-test FIXME #15883
use clone::Clone;
use cmp::{Eq, Equiv, PartialEq};
use collections::{Collection, Mutable, Set, MutableSet, Map, MutableMap};
use default::Default;
use fmt::Show;
use fmt;
use hash::{Hash, Hasher, RandomSipHasher};
use iter::{Iterator, FromIterator, FilterMap, Chain, Repeat, Zip, Extendable};
use iter;
use option::{Some, None};
use result::{Ok, Err};
use super::{HashMap, Entries, MoveEntries, INITIAL_CAPACITY};
// Future Optimization (FIXME!)
// =============================
//
// Iteration over zero sized values is a noop. There is no need
// for `bucket.val` in the case of HashSet. I suppose we would need HKT
// to get rid of it properly.
/// 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.
///
/// # Example
///
/// ```
/// use std::collections::HashSet;
/// // Type inference lets us omit an explicit type signature (which
/// // would be `HashSet<&str>` in this example).
/// let mut books = HashSet::new();
///
/// // Add some books.
/// books.insert("A Dance With Dragons");
/// books.insert("To Kill a Mockingbird");
/// books.insert("The Odyssey");
/// books.insert("The Great Gatsby");
///
/// // Check for a specific one.
/// if !books.contains(&("The Winds of Winter")) {
/// println!("We have {} books, but The Winds of Winter ain't one.",
/// books.len());
/// }
///
/// // Remove a book.
/// books.remove(&"The Odyssey");
///
/// // Iterate over everything.
/// for book in books.iter() {
/// println!("{}", *book);
/// }
/// ```
///
/// The easiest way to use `HashSet` with a custom type is to derive
/// `Eq` and `Hash`. We must also derive `PartialEq`, this will in the
/// future be implied by `Eq`.
///
/// ```
/// use std::collections::HashSet;
/// #[deriving(Hash, Eq, PartialEq, Show)]
/// struct Viking<'a> {
/// name: &'a str,
/// power: uint,
/// }
///
/// let mut vikings = HashSet::new();
///
/// vikings.insert(Viking { name: "Einar", power: 9u });
/// vikings.insert(Viking { name: "Einar", power: 9u });
/// vikings.insert(Viking { name: "Olaf", power: 4u });
/// vikings.insert(Viking { name: "Harald", power: 8u });
///
/// // Use derived implementation to print the vikings.
/// for x in vikings.iter() {
/// println!("{}", x);
/// }
/// ```
#[deriving(Clone)]
pub struct HashSet<T, H = RandomSipHasher> {
map: HashMap<T, (), H>
}
impl<T: Hash + Eq> HashSet<T, RandomSipHasher> {
/// Create an empty HashSet.
///
/// # Example
///
/// ```
/// use std::collections::HashSet;
/// let mut set: HashSet<int> = HashSet::new();
/// ```
#[inline]
pub fn new() -> HashSet<T, RandomSipHasher> {
HashSet::with_capacity(INITIAL_CAPACITY)
}
/// Create an empty HashSet with space for at least `n` elements in
/// the hash table.
///
/// # Example
///
/// ```
/// use std::collections::HashSet;
/// let mut set: HashSet<int> = HashSet::with_capacity(10);
/// ```
#[inline]
pub fn with_capacity(capacity: uint) -> HashSet<T, RandomSipHasher> {
HashSet { map: HashMap::with_capacity(capacity) }
}
}
impl<T: Eq + Hash<S>, S, H: Hasher<S>> HashSet<T, H> {
/// Creates a new empty hash set which will use the given hasher to hash
/// keys.
///
/// The hash set is also created with the default initial capacity.
///
/// # Example
///
/// ```
/// use std::collections::HashSet;
/// use std::hash::sip::SipHasher;
///
/// let h = SipHasher::new();
/// let mut set = HashSet::with_hasher(h);
/// set.insert(2u);
/// ```
#[inline]
pub fn with_hasher(hasher: H) -> HashSet<T, H> {
HashSet::with_capacity_and_hasher(INITIAL_CAPACITY, hasher)
}
/// Create an empty HashSet with space for at least `capacity`
/// elements in the hash table, using `hasher` to hash the keys.
///
/// Warning: `hasher` is normally randomly generated, and
/// is designed to allow `HashSet`s to be resistant to attacks that
/// cause many collisions and very poor performance. Setting it
/// manually using this function can expose a DoS attack vector.
///
/// # Example
///
/// ```
/// use std::collections::HashSet;
/// use std::hash::sip::SipHasher;
///
/// let h = SipHasher::new();
/// let mut set = HashSet::with_capacity_and_hasher(10u, h);
/// set.insert(1i);
/// ```
#[inline]
pub fn with_capacity_and_hasher(capacity: uint, hasher: H) -> HashSet<T, H> {
HashSet { map: HashMap::with_capacity_and_hasher(capacity, hasher) }
}
/// Reserve space for at least `n` elements in the hash table.
///
/// # Example
///
/// ```
/// use std::collections::HashSet;
/// let mut set: HashSet<int> = HashSet::new();
/// set.reserve(10);
/// ```
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.
///
/// # Example
///
/// This is a slightly silly example where we define the number's
/// parity as the equivalance class. It is important that the
/// values hash the same, which is why we implement `Hash`.
///
/// ```
/// use std::collections::HashSet;
/// use std::hash::Hash;
/// use std::hash::sip::SipState;
///
/// #[deriving(Eq, PartialEq)]
/// struct EvenOrOdd {
/// num: uint
/// };
///
/// impl Hash for EvenOrOdd {
/// fn hash(&self, state: &mut SipState) {
/// let parity = self.num % 2;
/// parity.hash(state);
/// }
/// }
///
/// impl Equiv<EvenOrOdd> for EvenOrOdd {
/// fn equiv(&self, other: &EvenOrOdd) -> bool {
/// self.num % 2 == other.num % 2
/// }
/// }
///
/// let mut set = HashSet::new();
/// set.insert(EvenOrOdd { num: 3u });
///
/// assert!(set.contains_equiv(&EvenOrOdd { num: 3u }));
/// assert!(set.contains_equiv(&EvenOrOdd { num: 5u }));
/// assert!(!set.contains_equiv(&EvenOrOdd { num: 4u }));
/// assert!(!set.contains_equiv(&EvenOrOdd { num: 2u }));
///
/// ```
pub fn contains_equiv<Q: Hash<S> + 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.
///
/// # Example
///
/// ```
/// use std::collections::HashSet;
/// let mut set = HashSet::new();
/// set.insert("a");
/// set.insert("b");
///
/// // Will print in an arbitrary order.
/// for x in set.iter() {
/// println!("{}", x);
/// }
/// ```
pub fn iter<'a>(&'a self) -> SetItems<'a, T> {
self.map.keys()
}
/// Deprecated: use `into_iter`.
#[deprecated = "use into_iter"]
pub fn move_iter(self) -> SetMoveItems<T> {
self.into_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.
///
/// # Example
///
/// ```
/// use std::collections::HashSet;
/// let mut set = HashSet::new();
/// set.insert("a".to_string());
/// set.insert("b".to_string());
///
/// // Not possible to collect to a Vec<String> with a regular `.iter()`.
/// let v: Vec<String> = set.into_iter().collect();
///
/// // Will print in an arbitrary order.
/// for x in v.iter() {
/// println!("{}", x);
/// }
/// ```
pub fn into_iter(self) -> SetMoveItems<T> {
self.map.into_iter().map(|(k, _)| k)
}
/// Visit the values representing the difference.
///
/// # Example
///
/// ```
/// use std::collections::HashSet;
/// let a: HashSet<int> = [1i, 2, 3].iter().map(|&x| x).collect();
/// let b: HashSet<int> = [4i, 2, 3, 4].iter().map(|&x| x).collect();
///
/// // Can be seen as `a - b`.
/// for x in a.difference(&b) {
/// println!("{}", x); // Print 1
/// }
///
/// let diff: HashSet<int> = a.difference(&b).map(|&x| x).collect();
/// assert_eq!(diff, [1i].iter().map(|&x| x).collect());
///
/// // Note that difference is not symmetric,
/// // and `b - a` means something else:
/// let diff: HashSet<int> = b.difference(&a).map(|&x| x).collect();
/// assert_eq!(diff, [4i].iter().map(|&x| x).collect());
/// ```
pub fn difference<'a>(&'a self, other: &'a HashSet<T, H>) -> SetAlgebraItems<'a, T, H> {
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.
///
/// # Example
///
/// ```
/// use std::collections::HashSet;
/// let a: HashSet<int> = [1i, 2, 3].iter().map(|&x| x).collect();
/// let b: HashSet<int> = [4i, 2, 3, 4].iter().map(|&x| x).collect();
///
/// // Print 1, 4 in arbitrary order.
/// for x in a.symmetric_difference(&b) {
/// println!("{}", x);
/// }
///
/// let diff1: HashSet<int> = a.symmetric_difference(&b).map(|&x| x).collect();
/// let diff2: HashSet<int> = b.symmetric_difference(&a).map(|&x| x).collect();
///
/// assert_eq!(diff1, diff2);
/// assert_eq!(diff1, [1i, 4].iter().map(|&x| x).collect());
/// ```
pub fn symmetric_difference<'a>(&'a self, other: &'a HashSet<T, H>)
-> Chain<SetAlgebraItems<'a, T, H>, SetAlgebraItems<'a, T, H>> {
self.difference(other).chain(other.difference(self))
}
/// Visit the values representing the intersection.
///
/// # Example
///
/// ```
/// use std::collections::HashSet;
/// let a: HashSet<int> = [1i, 2, 3].iter().map(|&x| x).collect();
/// let b: HashSet<int> = [4i, 2, 3, 4].iter().map(|&x| x).collect();
///
/// // Print 2, 3 in arbitrary order.
/// for x in a.intersection(&b) {
/// println!("{}", x);
/// }
///
/// let diff: HashSet<int> = a.intersection(&b).map(|&x| x).collect();
/// assert_eq!(diff, [2i, 3].iter().map(|&x| x).collect());
/// ```
pub fn intersection<'a>(&'a self, other: &'a HashSet<T, H>)
-> SetAlgebraItems<'a, T, H> {
Repeat::new(other).zip(self.iter())
.filter_map(|(other, elt)| {
if other.contains(elt) { Some(elt) } else { None }
})
}
/// Visit the values representing the union.
///
/// # Example
///
/// ```
/// use std::collections::HashSet;
/// let a: HashSet<int> = [1i, 2, 3].iter().map(|&x| x).collect();
/// let b: HashSet<int> = [4i, 2, 3, 4].iter().map(|&x| x).collect();
///
/// // Print 1, 2, 3, 4 in arbitrary order.
/// for x in a.union(&b) {
/// println!("{}", x);
/// }
///
/// let diff: HashSet<int> = a.union(&b).map(|&x| x).collect();
/// assert_eq!(diff, [1i, 2, 3, 4].iter().map(|&x| x).collect());
/// ```
pub fn union<'a>(&'a self, other: &'a HashSet<T, H>)
-> Chain<SetItems<'a, T>, SetAlgebraItems<'a, T, H>> {
self.iter().chain(other.difference(self))
}
}
impl<T: Eq + Hash<S>, S, H: Hasher<S>> PartialEq for HashSet<T, H> {
fn eq(&self, other: &HashSet<T, H>) -> bool {
if self.len() != other.len() { return false; }
self.iter().all(|key| other.contains(key))
}
}
impl<T: Eq + Hash<S>, S, H: Hasher<S>> Eq for HashSet<T, H> {}
impl<T: Eq + Hash<S>, S, H: Hasher<S>> Collection for HashSet<T, H> {
fn len(&self) -> uint { self.map.len() }
}
impl<T: Eq + Hash<S>, S, H: Hasher<S>> Mutable for HashSet<T, H> {
fn clear(&mut self) { self.map.clear() }
}
impl<T: Eq + Hash<S>, S, H: Hasher<S>> Set<T> for HashSet<T, H> {
fn contains(&self, value: &T) -> bool { self.map.contains_key(value) }
fn is_disjoint(&self, other: &HashSet<T, H>) -> bool {
self.iter().all(|v| !other.contains(v))
}
fn is_subset(&self, other: &HashSet<T, H>) -> bool {
self.iter().all(|v| other.contains(v))
}
}
impl<T: Eq + Hash<S>, S, H: Hasher<S>> MutableSet<T> for HashSet<T, H> {
fn insert(&mut self, value: T) -> bool { self.map.insert(value, ()) }
fn remove(&mut self, value: &T) -> bool { self.map.remove(value) }
}
impl<T: Eq + Hash<S> + fmt::Show, S, H: Hasher<S>> fmt::Show for HashSet<T, H> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
try!(write!(f, "{{"));
for (i, x) in self.iter().enumerate() {
if i != 0 { try!(write!(f, ", ")); }
try!(write!(f, "{}", *x));
}
write!(f, "}}")
}
}
impl<T: Eq + Hash<S>, S, H: Hasher<S> + Default> FromIterator<T> for HashSet<T, H> {
fn from_iter<I: Iterator<T>>(iter: I) -> HashSet<T, H> {
let (lower, _) = iter.size_hint();
let mut set = HashSet::with_capacity_and_hasher(lower, Default::default());
set.extend(iter);
set
}
}
impl<T: Eq + Hash<S>, S, H: Hasher<S> + Default> Extendable<T> for HashSet<T, H> {
fn extend<I: Iterator<T>>(&mut self, mut iter: I) {
for k in iter {
self.insert(k);
}
}
}
impl<T: Eq + Hash<S>, S, H: Hasher<S> + Default> Default for HashSet<T, H> {
fn default() -> HashSet<T, H> {
HashSet::with_hasher(Default::default())
}
}
/// HashSet iterator
pub type SetItems<'a, K> =
iter::Map<'static, (&'a K, &'a ()), &'a K, Entries<'a, K, ()>>;
/// HashSet move iterator
pub type SetMoveItems<K> =
iter::Map<'static, (K, ()), K, MoveEntries<K, ()>>;
// `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, H> =
FilterMap<'static, (&'a HashSet<T, H>, &'a T), &'a T,
Zip<Repeat<&'a HashSet<T, H>>, SetItems<'a, T>>>;
#[cfg(test)]
mod test_set {
use prelude::*;
use super::HashSet;
use slice::ImmutablePartialEqSlice;
use collections::Collection;
#[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(5i));
assert!(ys.insert(11i));
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(0i));
assert!(a.insert(5));
assert!(a.insert(11));
assert!(a.insert(7));
let mut b = HashSet::new();
assert!(b.insert(0i));
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: u32 = 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(11i));
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(2i));
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(1i));
assert!(a.insert(3));
assert!(a.insert(5));
assert!(a.insert(9));
assert!(a.insert(11));
assert!(b.insert(3i));
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(1i));
assert!(a.insert(3));
assert!(a.insert(5));
assert!(a.insert(9));
assert!(a.insert(11));
assert!(b.insert(-2i));
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(1i));
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(-2i));
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 = [1i, 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.into_iter().collect::<Vec<char>>();
assert!(['a', 'b'] == v.as_slice() || ['b', 'a'] == v.as_slice());
}
#[test]
fn test_eq() {
// These constants once happened to expose a bug in insert().
// I'm keeping them around to prevent a regression.
let mut s1 = HashSet::new();
s1.insert(1i);
s1.insert(2);
s1.insert(3);
let mut s2 = HashSet::new();
s2.insert(1i);
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(1i);
set.insert(2);
let set_str = format!("{}", set);
assert!(set_str == "{1, 2}".to_string() || set_str == "{2, 1}".to_string());
assert_eq!(format!("{}", empty), "{}".to_string());
}
}