KevinMidboe/linguist
1
0
Fork 0
mirror of https://github.com/KevinMidboe/linguist.git synced 2025-10-29 17:50:22 +00:00
Code Issues Packages Projects Releases Wiki Activity
Files
35a13b363372b77542c4d712868eff29d3147a96
linguist/samples/Rust/hashmap.rs

2325 lines
71 KiB
Rust
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

// Copyright 2014-2015 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.
use self::Entry::*;
use self::SearchResult::*;
use self::VacantEntryState::*;
use borrow::Borrow;
use clone::Clone;
use cmp::{max, Eq, PartialEq};
use default::Default;
use fmt::{self, Debug};
use hash::{Hash, SipHasher};
use iter::{self, Iterator, ExactSizeIterator, IntoIterator, FromIterator, Extend, Map};
use marker::Sized;
use mem::{self, replace};
use ops::{Deref, FnMut, FnOnce, Index};
use option::Option::{self, Some, None};
use rand::{self, Rng};
use result::Result::{self, Ok, Err};
use super::table::{
self,
Bucket,
EmptyBucket,
FullBucket,
FullBucketImm,
FullBucketMut,
RawTable,
SafeHash
};
use super::table::BucketState::{
Empty,
Full,
};
use super::state::HashState;
const INITIAL_LOG2_CAP: usize = 5;
#[unstable(feature = "std_misc")]
pub const INITIAL_CAPACITY: usize = 1 << INITIAL_LOG2_CAP; // 2^5
/// The default behavior of HashMap implements a load factor of 90.9%.
/// This behavior is characterized by the following condition:
///
/// - if size > 0.909 * capacity: grow the map
#[derive(Clone)]
struct DefaultResizePolicy;
impl DefaultResizePolicy {
fn new() -> DefaultResizePolicy {
DefaultResizePolicy
}
#[inline]
fn min_capacity(&self, usable_size: usize) -> usize {
// Here, we are rephrasing the logic by specifying the lower limit
// on capacity:
//
// - if `cap < size * 1.1`: grow the map
usable_size * 11 / 10
}
/// An inverse of `min_capacity`, approximately.
#[inline]
fn usable_capacity(&self, cap: usize) -> usize {
// As the number of entries approaches usable capacity,
// min_capacity(size) must be smaller than the internal capacity,
// so that the map is not resized:
// `min_capacity(usable_capacity(x)) <= x`.
// The left-hand side can only be smaller due to flooring by integer
// division.
//
// This doesn't have to be checked for overflow since allocation size
// in bytes will overflow earlier than multiplication by 10.
cap * 10 / 11
}
}
#[test]
fn test_resize_policy() {
let rp = DefaultResizePolicy;
for n in 0..1000 {
assert!(rp.min_capacity(rp.usable_capacity(n)) <= n);
assert!(rp.usable_capacity(rp.min_capacity(n)) <= n);
}
}
// The main performance trick in this hashmap is called Robin Hood Hashing.
// It gains its excellent performance from one essential operation:
//
// If an insertion collides with an existing element, and that element's
// "probe distance" (how far away the element is from its ideal location)
// is higher than how far we've already probed, swap the elements.
//
// This massively lowers variance in probe distance, and allows us to get very
// high load factors with good performance. The 90% load factor I use is rather
// conservative.
//
// > Why a load factor of approximately 90%?
//
// In general, all the distances to initial buckets will converge on the mean.
// At a load factor of α, the odds of finding the target bucket after k
// probes is approximately 1-α^k. If we set this equal to 50% (since we converge
// on the mean) and set k=8 (64-byte cache line / 8-byte hash), α=0.92. I round
// this down to make the math easier on the CPU and avoid its FPU.
// Since on average we start the probing in the middle of a cache line, this
// strategy pulls in two cache lines of hashes on every lookup. I think that's
// pretty good, but if you want to trade off some space, it could go down to one
// cache line on average with an α of 0.84.
//
// > Wait, what? Where did you get 1-α^k from?
//
// On the first probe, your odds of a collision with an existing element is α.
// The odds of doing this twice in a row is approximately α^2. For three times,
// α^3, etc. Therefore, the odds of colliding k times is α^k. The odds of NOT
// colliding after k tries is 1-α^k.
//
// The paper from 1986 cited below mentions an implementation which keeps track
// of the distance-to-initial-bucket histogram. This approach is not suitable
// for modern architectures because it requires maintaining an internal data
// structure. This allows very good first guesses, but we are most concerned
// with guessing entire cache lines, not individual indexes. Furthermore, array
// accesses are no longer linear and in one direction, as we have now. There
// is also memory and cache pressure that this would entail that would be very
// difficult to properly see in a microbenchmark.
//
// ## Future Improvements (FIXME!)
//
// Allow the load factor to be changed dynamically and/or at initialization.
//
// Also, would it be possible for us to reuse storage when growing the
// underlying table? This is exactly the use case for 'realloc', and may
// be worth exploring.
//
// ## Future Optimizations (FIXME!)
//
// Another possible design choice that I made without any real reason is
// parameterizing the raw table over keys and values. Technically, all we need
// is the size and alignment of keys and values, and the code should be just as
// efficient (well, we might need one for power-of-two size and one for not...).
// This has the potential to reduce code bloat in rust executables, without
// really losing anything except 4 words (key size, key alignment, val size,
// val alignment) which can be passed in to every call of a `RawTable` function.
// This would definitely be an avenue worth exploring if people start complaining
// about the size of rust executables.
//
// Annotate exceedingly likely branches in `table::make_hash`
// and `search_hashed` to reduce instruction cache pressure
// and mispredictions once it becomes possible (blocked on issue #11092).
//
// Shrinking the table could simply reallocate in place after moving buckets
// to the first half.
//
// The growth algorithm (fragment of the Proof of Correctness)
// --------------------
//
// The growth algorithm is basically a fast path of the naive reinsertion-
// during-resize algorithm. Other paths should never be taken.
//
// Consider growing a robin hood hashtable of capacity n. Normally, we do this
// by allocating a new table of capacity `2n`, and then individually reinsert
// each element in the old table into the new one. This guarantees that the
// new table is a valid robin hood hashtable with all the desired statistical
// properties. Remark that the order we reinsert the elements in should not
// matter. For simplicity and efficiency, we will consider only linear
// reinsertions, which consist of reinserting all elements in the old table
// into the new one by increasing order of index. However we will not be
// starting our reinsertions from index 0 in general. If we start from index
// i, for the purpose of reinsertion we will consider all elements with real
// index j < i to have virtual index n + j.
//
// Our hash generation scheme consists of generating a 64-bit hash and
// truncating the most significant bits. When moving to the new table, we
// simply introduce a new bit to the front of the hash. Therefore, if an
// elements has ideal index i in the old table, it can have one of two ideal
// locations in the new table. If the new bit is 0, then the new ideal index
// is i. If the new bit is 1, then the new ideal index is n + i. Intuitively,
// we are producing two independent tables of size n, and for each element we
// independently choose which table to insert it into with equal probability.
// However the rather than wrapping around themselves on overflowing their
// indexes, the first table overflows into the first, and the first into the
// second. Visually, our new table will look something like:
//
// [yy_xxx_xxxx_xxx|xx_yyy_yyyy_yyy]
//
// Where x's are elements inserted into the first table, y's are elements
// inserted into the second, and _'s are empty sections. We now define a few
// key concepts that we will use later. Note that this is a very abstract
// perspective of the table. A real resized table would be at least half
// empty.
//
// Theorem: A linear robin hood reinsertion from the first ideal element
// produces identical results to a linear naive reinsertion from the same
// element.
//
// FIXME(Gankro, pczarn): review the proof and put it all in a separate README.md
/// A hash map implementation which uses linear probing with Robin
/// Hood bucket stealing.
///
/// The hashes are all keyed by the thread-local random number generator
/// on creation by default. This means that the ordering of the keys is
/// randomized, but makes the tables more resistant to
/// denial-of-service attacks (Hash DoS). This behaviour can be
/// overridden with one of the constructors.
///
/// It is required that the keys implement the `Eq` and `Hash` traits, although
/// this can frequently be achieved by using `#[derive(PartialEq, Eq, Hash)]`.
/// If you implement these yourself, it is important that the following
/// property holds:
///
/// ```text
/// k1 == k2 -> hash(k1) == hash(k2)
/// ```
///
/// In other words, if two keys are equal, their hashes must be equal.
///
/// It is a logic error for a key to be modified in such a way that the key's
/// hash, as determined by the `Hash` trait, or its equality, as determined by
/// the `Eq` trait, changes while it is in the map. This is normally only
/// possible through `Cell`, `RefCell`, global state, I/O, or unsafe code.
///
/// Relevant papers/articles:
///
/// 1. Pedro Celis. ["Robin Hood Hashing"](https://cs.uwaterloo.ca/research/tr/1986/CS-86-14.pdf)
/// 2. Emmanuel Goossaert. ["Robin Hood
/// hashing"](http://codecapsule.com/2013/11/11/robin-hood-hashing/)
/// 3. Emmanuel Goossaert. ["Robin Hood hashing: backward shift
/// deletion"](http://codecapsule.com/2013/11/17/robin-hood-hashing-backward-shift-deletion/)
///
/// # Examples
///
/// ```
/// use std::collections::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 Huckleberry Finn", "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 {
/// match book_reviews.get(book) {
/// Some(review) => println!("{}: {}", book, review),
/// None => println!("{} is unreviewed.", book)
/// }
/// }
///
/// // iterate over everything.
/// for (book, review) in &book_reviews {
/// println!("{}: \"{}\"", book, review);
/// }
/// ```
///
/// The easiest way to use `HashMap` with a custom type as key is to derive `Eq` and `Hash`.
/// We must also derive `PartialEq`.
///
/// ```
/// use std::collections::HashMap;
///
/// #[derive(Hash, Eq, PartialEq, Debug)]
/// struct Viking {
/// name: String,
/// country: String,
/// }
///
/// impl Viking {
/// /// Create a new Viking.
/// fn new(name: &str, country: &str) -> Viking {
/// Viking { name: name.to_string(), country: country.to_string() }
/// }
/// }
///
/// // Use a HashMap to store the vikings' health points.
/// let mut vikings = HashMap::new();
///
/// vikings.insert(Viking::new("Einar", "Norway"), 25);
/// vikings.insert(Viking::new("Olaf", "Denmark"), 24);
/// vikings.insert(Viking::new("Harald", "Iceland"), 12);
///
/// // Use derived implementation to print the status of the vikings.
/// for (viking, health) in &vikings {
/// println!("{:?} has {} hp", viking, health);
/// }
/// ```
#[derive(Clone)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct HashMap<K, V, S = RandomState> {
// All hashes are keyed on these values, to prevent hash collision attacks.
hash_state: S,
table: RawTable<K, V>,
resize_policy: DefaultResizePolicy,
}
/// Search for a pre-hashed key.
fn search_hashed<K, V, M, F>(table: M,
hash: SafeHash,
mut is_match: F)
-> SearchResult<K, V, M> where
M: Deref<Target=RawTable<K, V>>,
F: FnMut(&K) -> bool,
{
// This is the only function where capacity can be zero. To avoid
// undefined behaviour when Bucket::new gets the raw bucket in this
// case, immediately return the appropriate search result.
if table.capacity() == 0 {
return TableRef(table);
}
let size = table.size();
let mut probe = Bucket::new(table, hash);
let ib = probe.index();
while probe.index() != ib + size {
let full = match probe.peek() {
Empty(b) => return TableRef(b.into_table()), // hit an empty bucket
Full(b) => b
};
if full.distance() + ib < full.index() {
// We can finish the search early if we hit any bucket
// with a lower distance to initial bucket than we've probed.
return TableRef(full.into_table());
}
// If the hash doesn't match, it can't be this one..
if hash == full.hash() {
// If the key doesn't match, it can't be this one..
if is_match(full.read().0) {
return FoundExisting(full);
}
}
probe = full.next();
}
TableRef(probe.into_table())
}
fn pop_internal<K, V>(starting_bucket: FullBucketMut<K, V>) -> (K, V) {
let (empty, retkey, retval) = starting_bucket.take();
let mut gap = match empty.gap_peek() {
Some(b) => b,
None => return (retkey, retval)
};
while gap.full().distance() != 0 {
gap = match gap.shift() {
Some(b) => b,
None => break
};
}
// Now we've done all our shifting. Return the value we grabbed earlier.
(retkey, retval)
}
/// Perform robin hood bucket stealing at the given `bucket`. You must
/// also pass the position of that bucket's initial bucket so we don't have
/// to recalculate it.
///
/// `hash`, `k`, and `v` are the elements to "robin hood" into the hashtable.
fn robin_hood<'a, K: 'a, V: 'a>(mut bucket: FullBucketMut<'a, K, V>,
mut ib: usize,
mut hash: SafeHash,
mut k: K,
mut v: V)
-> &'a mut V {
let starting_index = bucket.index();
let size = {
let table = bucket.table(); // FIXME "lifetime too short".
table.size()
};
// There can be at most `size - dib` buckets to displace, because
// in the worst case, there are `size` elements and we already are
// `distance` buckets away from the initial one.
let idx_end = starting_index + size - bucket.distance();
loop {
let (old_hash, old_key, old_val) = bucket.replace(hash, k, v);
loop {
let probe = bucket.next();
assert!(probe.index() != idx_end);
let full_bucket = match probe.peek() {
Empty(bucket) => {
// Found a hole!
let b = bucket.put(old_hash, old_key, old_val);
// Now that it's stolen, just read the value's pointer
// right out of the table!
return Bucket::at_index(b.into_table(), starting_index)
.peek()
.expect_full()
.into_mut_refs()
.1;
},
Full(bucket) => bucket
};
let probe_ib = full_bucket.index() - full_bucket.distance();
bucket = full_bucket;
// Robin hood! Steal the spot.
if ib < probe_ib {
ib = probe_ib;
hash = old_hash;
k = old_key;
v = old_val;
break;
}
}
}
}
/// A result that works like Option<FullBucket<..>> but preserves
/// the reference that grants us access to the table in any case.
enum SearchResult<K, V, M> {
// This is an entry that holds the given key:
FoundExisting(FullBucket<K, V, M>),
// There was no such entry. The reference is given back:
TableRef(M)
}
impl<K, V, M> SearchResult<K, V, M> {
fn into_option(self) -> Option<FullBucket<K, V, M>> {
match self {
FoundExisting(bucket) => Some(bucket),
TableRef(_) => None
}
}
}
impl<K, V, S> HashMap<K, V, S>
where K: Eq + Hash, S: HashState
{
fn make_hash<X: ?Sized>(&self, x: &X) -> SafeHash where X: Hash {
table::make_hash(&self.hash_state, x)
}
/// Search for a key, yielding the index if it's found in the hashtable.
/// If you already have the hash for the key lying around, use
/// search_hashed.
fn search<'a, Q: ?Sized>(&'a self, q: &Q) -> Option<FullBucketImm<'a, K, V>>
where K: Borrow<Q>, Q: Eq + Hash
{
let hash = self.make_hash(q);
search_hashed(&self.table, hash, |k| q.eq(k.borrow()))
.into_option()
}
fn search_mut<'a, Q: ?Sized>(&'a mut self, q: &Q) -> Option<FullBucketMut<'a, K, V>>
where K: Borrow<Q>, Q: Eq + Hash
{
let hash = self.make_hash(q);
search_hashed(&mut self.table, hash, |k| q.eq(k.borrow()))
.into_option()
}
// The caller should ensure that invariants by Robin Hood Hashing hold.
fn insert_hashed_ordered(&mut self, hash: SafeHash, k: K, v: V) {
let cap = self.table.capacity();
let mut buckets = Bucket::new(&mut self.table, hash);
let ib = buckets.index();
while buckets.index() != ib + cap {
// We don't need to compare hashes for value swap.
// Not even DIBs for Robin Hood.
buckets = match buckets.peek() {
Empty(empty) => {
empty.put(hash, k, v);
return;
}
Full(b) => b.into_bucket()
};
buckets.next();
}
panic!("Internal HashMap error: Out of space.");
}
}
impl<K: Hash + Eq, V> HashMap<K, V, RandomState> {
/// Creates an empty HashMap.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
/// let mut map: HashMap<&str, isize> = HashMap::new();
/// ```
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub fn new() -> HashMap<K, V, RandomState> {
Default::default()
}
/// Creates an empty hash map with the given initial capacity.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
/// let mut map: HashMap<&str, isize> = HashMap::with_capacity(10);
/// ```
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub fn with_capacity(capacity: usize) -> HashMap<K, V, RandomState> {
HashMap::with_capacity_and_hash_state(capacity, Default::default())
}
}
impl<K, V, S> HashMap<K, V, S>
where K: Eq + Hash, S: HashState
{
/// Creates an empty hashmap which will use the given hasher to hash keys.
///
/// The created map has the default initial capacity.
///
/// # Examples
///
/// ```
/// # #![feature(std_misc)]
/// use std::collections::HashMap;
/// use std::collections::hash_map::RandomState;
///
/// let s = RandomState::new();
/// let mut map = HashMap::with_hash_state(s);
/// map.insert(1, 2);
/// ```
#[inline]
#[unstable(feature = "std_misc", reason = "hasher stuff is unclear")]
pub fn with_hash_state(hash_state: S) -> HashMap<K, V, S> {
HashMap {
hash_state: hash_state,
resize_policy: DefaultResizePolicy::new(),
table: RawTable::new(0),
}
}
/// Creates an empty HashMap with space for at least `capacity`
/// elements, using `hasher` to hash the keys.
///
/// Warning: `hasher` is normally randomly generated, and
/// is designed to allow HashMaps 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.
///
/// # Examples
///
/// ```
/// # #![feature(std_misc)]
/// use std::collections::HashMap;
/// use std::collections::hash_map::RandomState;
///
/// let s = RandomState::new();
/// let mut map = HashMap::with_capacity_and_hash_state(10, s);
/// map.insert(1, 2);
/// ```
#[inline]
#[unstable(feature = "std_misc", reason = "hasher stuff is unclear")]
pub fn with_capacity_and_hash_state(capacity: usize, hash_state: S)
-> HashMap<K, V, S> {
let resize_policy = DefaultResizePolicy::new();
let min_cap = max(INITIAL_CAPACITY, resize_policy.min_capacity(capacity));
let internal_cap = min_cap.checked_next_power_of_two().expect("capacity overflow");
assert!(internal_cap >= capacity, "capacity overflow");
HashMap {
hash_state: hash_state,
resize_policy: resize_policy,
table: RawTable::new(internal_cap),
}
}
/// Returns the number of elements the map can hold without reallocating.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
/// let map: HashMap<isize, isize> = HashMap::with_capacity(100);
/// assert!(map.capacity() >= 100);
/// ```
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub fn capacity(&self) -> usize {
self.resize_policy.usable_capacity(self.table.capacity())
}
/// Reserves capacity for at least `additional` more elements to be inserted
/// in the `HashMap`. The collection may reserve more space to avoid
/// frequent reallocations.
///
/// # Panics
///
/// Panics if the new allocation size overflows `usize`.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
/// let mut map: HashMap<&str, isize> = HashMap::new();
/// map.reserve(10);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn reserve(&mut self, additional: usize) {
let new_size = self.len().checked_add(additional).expect("capacity overflow");
let min_cap = self.resize_policy.min_capacity(new_size);
// An invalid value shouldn't make us run out of space. This includes
// an overflow check.
assert!(new_size <= min_cap);
if self.table.capacity() < min_cap {
let new_capacity = max(min_cap.next_power_of_two(), INITIAL_CAPACITY);
self.resize(new_capacity);
}
}
/// Resizes the internal vectors to a new capacity. It's your responsibility to:
/// 1) Make sure the new capacity is enough for all the elements, accounting
/// for the load factor.
/// 2) Ensure new_capacity is a power of two or zero.
fn resize(&mut self, new_capacity: usize) {
assert!(self.table.size() <= new_capacity);
assert!(new_capacity.is_power_of_two() || new_capacity == 0);
let mut old_table = replace(&mut self.table, RawTable::new(new_capacity));
let old_size = old_table.size();
if old_table.capacity() == 0 || old_table.size() == 0 {
return;
}
// Grow the table.
// Specialization of the other branch.
let mut bucket = Bucket::first(&mut old_table);
// "So a few of the first shall be last: for many be called,
// but few chosen."
//
// We'll most likely encounter a few buckets at the beginning that
// have their initial buckets near the end of the table. They were
// placed at the beginning as the probe wrapped around the table
// during insertion. We must skip forward to a bucket that won't
// get reinserted too early and won't unfairly steal others spot.
// This eliminates the need for robin hood.
loop {
bucket = match bucket.peek() {
Full(full) => {
if full.distance() == 0 {
// This bucket occupies its ideal spot.
// It indicates the start of another "cluster".
bucket = full.into_bucket();
break;
}
// Leaving this bucket in the last cluster for later.
full.into_bucket()
}
Empty(b) => {
// Encountered a hole between clusters.
b.into_bucket()
}
};
bucket.next();
}
// This is how the buckets might be laid out in memory:
// ($ marks an initialized bucket)
// ________________
// |$$$_$$$$$$_$$$$$|
//
// But we've skipped the entire initial cluster of buckets
// and will continue iteration in this order:
// ________________
// |$$$$$$_$$$$$
// ^ wrap around once end is reached
// ________________
// $$$_____________|
// ^ exit once table.size == 0
loop {
bucket = match bucket.peek() {
Full(bucket) => {
let h = bucket.hash();
let (b, k, v) = bucket.take();
self.insert_hashed_ordered(h, k, v);
{
let t = b.table(); // FIXME "lifetime too short".
if t.size() == 0 { break }
};
b.into_bucket()
}
Empty(b) => b.into_bucket()
};
bucket.next();
}
assert_eq!(self.table.size(), old_size);
}
/// Shrinks the capacity of the map as much as possible. It will drop
/// down as much as possible while maintaining the internal rules
/// and possibly leaving some space in accordance with the resize policy.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut map: HashMap<isize, isize> = HashMap::with_capacity(100);
/// map.insert(1, 2);
/// map.insert(3, 4);
/// assert!(map.capacity() >= 100);
/// map.shrink_to_fit();
/// assert!(map.capacity() >= 2);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn shrink_to_fit(&mut self) {
let min_capacity = self.resize_policy.min_capacity(self.len());
let min_capacity = max(min_capacity.next_power_of_two(), INITIAL_CAPACITY);
// An invalid value shouldn't make us run out of space.
debug_assert!(self.len() <= min_capacity);
if self.table.capacity() != min_capacity {
let old_table = replace(&mut self.table, RawTable::new(min_capacity));
let old_size = old_table.size();
// Shrink the table. Naive algorithm for resizing:
for (h, k, v) in old_table.into_iter() {
self.insert_hashed_nocheck(h, k, v);
}
debug_assert_eq!(self.table.size(), old_size);
}
}
/// Insert a pre-hashed key-value pair, without first checking
/// that there's enough room in the buckets. Returns a reference to the
/// newly insert value.
///
/// If the key already exists, the hashtable will be returned untouched
/// and a reference to the existing element will be returned.
fn insert_hashed_nocheck(&mut self, hash: SafeHash, k: K, v: V) -> &mut V {
self.insert_or_replace_with(hash, k, v, |_, _, _| ())
}
fn insert_or_replace_with<'a, F>(&'a mut self,
hash: SafeHash,
k: K,
v: V,
mut found_existing: F)
-> &'a mut V where
F: FnMut(&mut K, &mut V, V),
{
// Worst case, we'll find one empty bucket among `size + 1` buckets.
let size = self.table.size();
let mut probe = Bucket::new(&mut self.table, hash);
let ib = probe.index();
loop {
let mut bucket = match probe.peek() {
Empty(bucket) => {
// Found a hole!
return bucket.put(hash, k, v).into_mut_refs().1;
}
Full(bucket) => bucket
};
// hash matches?
if bucket.hash() == hash {
// key matches?
if k == *bucket.read_mut().0 {
let (bucket_k, bucket_v) = bucket.into_mut_refs();
debug_assert!(k == *bucket_k);
// Key already exists. Get its reference.
found_existing(bucket_k, bucket_v, v);
return bucket_v;
}
}
let robin_ib = bucket.index() as isize - bucket.distance() as isize;
if (ib as isize) < robin_ib {
// Found a luckier bucket than me. Better steal his spot.
return robin_hood(bucket, robin_ib as usize, hash, k, v);
}
probe = bucket.next();
assert!(probe.index() != ib + size + 1);
}
}
/// An iterator visiting all keys in arbitrary order.
/// Iterator element type is `&'a K`.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut map = HashMap::new();
/// map.insert("a", 1);
/// map.insert("b", 2);
/// map.insert("c", 3);
///
/// for key in map.keys() {
/// println!("{}", key);
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn keys<'a>(&'a self) -> Keys<'a, K, V> {
fn first<A, B>((a, _): (A, B)) -> A { a }
let first: fn((&'a K,&'a V)) -> &'a K = first; // coerce to fn ptr
Keys { inner: self.iter().map(first) }
}
/// An iterator visiting all values in arbitrary order.
/// Iterator element type is `&'a V`.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut map = HashMap::new();
/// map.insert("a", 1);
/// map.insert("b", 2);
/// map.insert("c", 3);
///
/// for val in map.values() {
/// println!("{}", val);
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn values<'a>(&'a self) -> Values<'a, K, V> {
fn second<A, B>((_, b): (A, B)) -> B { b }
let second: fn((&'a K,&'a V)) -> &'a V = second; // coerce to fn ptr
Values { inner: self.iter().map(second) }
}
/// An iterator visiting all key-value pairs in arbitrary order.
/// Iterator element type is `(&'a K, &'a V)`.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut map = HashMap::new();
/// map.insert("a", 1);
/// map.insert("b", 2);
/// map.insert("c", 3);
///
/// for (key, val) in map.iter() {
/// println!("key: {} val: {}", key, val);
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn iter(&self) -> Iter<K, V> {
Iter { inner: self.table.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)`.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut map = HashMap::new();
/// map.insert("a", 1);
/// map.insert("b", 2);
/// map.insert("c", 3);
///
/// // Update all values
/// for (_, val) in map.iter_mut() {
/// *val *= 2;
/// }
///
/// for (key, val) in map.iter() {
/// println!("key: {} val: {}", key, val);
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn iter_mut(&mut self) -> IterMut<K, V> {
IterMut { inner: self.table.iter_mut() }
}
/// Gets the given key's corresponding entry in the map for in-place manipulation.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut letters = HashMap::new();
///
/// for ch in "a short treatise on fungi".chars() {
/// let counter = letters.entry(ch).or_insert(0);
/// *counter += 1;
/// }
///
/// assert_eq!(letters[&'s'], 2);
/// assert_eq!(letters[&'t'], 3);
/// assert_eq!(letters[&'u'], 1);
/// assert_eq!(letters.get(&'y'), None);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn entry(&mut self, key: K) -> Entry<K, V> {
// Gotta resize now.
self.reserve(1);
let hash = self.make_hash(&key);
search_entry_hashed(&mut self.table, hash, key)
}
/// Returns the number of elements in the map.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut a = HashMap::new();
/// assert_eq!(a.len(), 0);
/// a.insert(1, "a");
/// assert_eq!(a.len(), 1);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn len(&self) -> usize { self.table.size() }
/// Returns true if the map contains no elements.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut a = HashMap::new();
/// assert!(a.is_empty());
/// a.insert(1, "a");
/// assert!(!a.is_empty());
/// ```
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub fn is_empty(&self) -> bool { self.len() == 0 }
/// Clears the map, returning all key-value pairs as an iterator. Keeps the
/// allocated memory for reuse.
///
/// # Examples
///
/// ```
/// # #![feature(std_misc)]
/// use std::collections::HashMap;
///
/// let mut a = HashMap::new();
/// a.insert(1, "a");
/// a.insert(2, "b");
///
/// for (k, v) in a.drain().take(1) {
/// assert!(k == 1 || k == 2);
/// assert!(v == "a" || v == "b");
/// }
///
/// assert!(a.is_empty());
/// ```
#[inline]
#[unstable(feature = "std_misc",
reason = "matches collection reform specification, waiting for dust to settle")]
pub fn drain(&mut self) -> Drain<K, V> {
fn last_two<A, B, C>((_, b, c): (A, B, C)) -> (B, C) { (b, c) }
let last_two: fn((SafeHash, K, V)) -> (K, V) = last_two; // coerce to fn pointer
Drain {
inner: self.table.drain().map(last_two),
}
}
/// Clears the map, removing all key-value pairs. Keeps the allocated memory
/// for reuse.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut a = HashMap::new();
/// a.insert(1, "a");
/// a.clear();
/// assert!(a.is_empty());
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn clear(&mut self) {
self.drain();
}
/// Returns a reference to the value corresponding to the key.
///
/// The key may be any borrowed form of the map's key type, but
/// `Hash` and `Eq` on the borrowed form *must* match those for
/// the key type.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut map = HashMap::new();
/// map.insert(1, "a");
/// assert_eq!(map.get(&1), Some(&"a"));
/// assert_eq!(map.get(&2), None);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn get<Q: ?Sized>(&self, k: &Q) -> Option<&V>
where K: Borrow<Q>, Q: Hash + Eq
{
self.search(k).map(|bucket| bucket.into_refs().1)
}
/// Returns true if the map contains a value for the specified key.
///
/// The key may be any borrowed form of the map's key type, but
/// `Hash` and `Eq` on the borrowed form *must* match those for
/// the key type.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut map = HashMap::new();
/// map.insert(1, "a");
/// assert_eq!(map.contains_key(&1), true);
/// assert_eq!(map.contains_key(&2), false);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn contains_key<Q: ?Sized>(&self, k: &Q) -> bool
where K: Borrow<Q>, Q: Hash + Eq
{
self.search(k).is_some()
}
/// Returns a mutable reference to the value corresponding to the key.
///
/// The key may be any borrowed form of the map's key type, but
/// `Hash` and `Eq` on the borrowed form *must* match those for
/// the key type.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut map = HashMap::new();
/// map.insert(1, "a");
/// if let Some(x) = map.get_mut(&1) {
/// *x = "b";
/// }
/// assert_eq!(map[&1], "b");
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn get_mut<Q: ?Sized>(&mut self, k: &Q) -> Option<&mut V>
where K: Borrow<Q>, Q: Hash + Eq
{
self.search_mut(k).map(|bucket| bucket.into_mut_refs().1)
}
/// Inserts a key-value pair into the map. If the key already had a value
/// present in the map, that value is returned. Otherwise, `None` is returned.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut map = HashMap::new();
/// assert_eq!(map.insert(37, "a"), None);
/// assert_eq!(map.is_empty(), false);
///
/// map.insert(37, "b");
/// assert_eq!(map.insert(37, "c"), Some("b"));
/// assert_eq!(map[&37], "c");
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn insert(&mut self, k: K, v: V) -> Option<V> {
let hash = self.make_hash(&k);
self.reserve(1);
let mut retval = None;
self.insert_or_replace_with(hash, k, v, |_, val_ref, val| {
retval = Some(replace(val_ref, val));
});
retval
}
/// Removes a key from the map, returning the value at the key if the key
/// was previously in the map.
///
/// The key may be any borrowed form of the map's key type, but
/// `Hash` and `Eq` on the borrowed form *must* match those for
/// the key type.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut map = HashMap::new();
/// map.insert(1, "a");
/// assert_eq!(map.remove(&1), Some("a"));
/// assert_eq!(map.remove(&1), None);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn remove<Q: ?Sized>(&mut self, k: &Q) -> Option<V>
where K: Borrow<Q>, Q: Hash + Eq
{
if self.table.size() == 0 {
return None
}
self.search_mut(k).map(|bucket| pop_internal(bucket).1)
}
}
fn search_entry_hashed<'a, K: Eq, V>(table: &'a mut RawTable<K,V>, hash: SafeHash, k: K)
-> Entry<'a, K, V>
{
// Worst case, we'll find one empty bucket among `size + 1` buckets.
let size = table.size();
let mut probe = Bucket::new(table, hash);
let ib = probe.index();
loop {
let bucket = match probe.peek() {
Empty(bucket) => {
// Found a hole!
return Vacant(VacantEntry {
hash: hash,
key: k,
elem: NoElem(bucket),
});
},
Full(bucket) => bucket
};
// hash matches?
if bucket.hash() == hash {
// key matches?
if k == *bucket.read().0 {
return Occupied(OccupiedEntry{
elem: bucket,
});
}
}
let robin_ib = bucket.index() as isize - bucket.distance() as isize;
if (ib as isize) < robin_ib {
// Found a luckier bucket than me. Better steal his spot.
return Vacant(VacantEntry {
hash: hash,
key: k,
elem: NeqElem(bucket, robin_ib as usize),
});
}
probe = bucket.next();
assert!(probe.index() != ib + size + 1);
}
}
impl<K, V, S> PartialEq for HashMap<K, V, S>
where K: Eq + Hash, V: PartialEq, S: HashState
{
fn eq(&self, other: &HashMap<K, V, S>) -> bool {
if self.len() != other.len() { return false; }
self.iter().all(|(key, value)|
other.get(key).map_or(false, |v| *value == *v)
)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V, S> Eq for HashMap<K, V, S>
where K: Eq + Hash, V: Eq, S: HashState
{}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V, S> Debug for HashMap<K, V, S>
where K: Eq + Hash + Debug, V: Debug, S: HashState
{
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_map().entries(self.iter()).finish()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V, S> Default for HashMap<K, V, S>
where K: Eq + Hash,
S: HashState + Default,
{
fn default() -> HashMap<K, V, S> {
HashMap::with_hash_state(Default::default())
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, Q: ?Sized, V, S> Index<&'a Q> for HashMap<K, V, S>
where K: Eq + Hash + Borrow<Q>,
Q: Eq + Hash,
S: HashState,
{
type Output = V;
#[inline]
fn index(&self, index: &Q) -> &V {
self.get(index).expect("no entry found for key")
}
}
/// HashMap iterator.
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Iter<'a, K: 'a, V: 'a> {
inner: table::Iter<'a, K, V>
}
// FIXME(#19839) Remove in favor of `#[derive(Clone)]`
impl<'a, K, V> Clone for Iter<'a, K, V> {
fn clone(&self) -> Iter<'a, K, V> {
Iter {
inner: self.inner.clone()
}
}
}
/// HashMap mutable values iterator.
#[stable(feature = "rust1", since = "1.0.0")]
pub struct IterMut<'a, K: 'a, V: 'a> {
inner: table::IterMut<'a, K, V>
}
/// HashMap move iterator.
#[stable(feature = "rust1", since = "1.0.0")]
pub struct IntoIter<K, V> {
inner: iter::Map<table::IntoIter<K, V>, fn((SafeHash, K, V)) -> (K, V)>
}
/// HashMap keys iterator.
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Keys<'a, K: 'a, V: 'a> {
inner: Map<Iter<'a, K, V>, fn((&'a K, &'a V)) -> &'a K>
}
// FIXME(#19839) Remove in favor of `#[derive(Clone)]`
impl<'a, K, V> Clone for Keys<'a, K, V> {
fn clone(&self) -> Keys<'a, K, V> {
Keys {
inner: self.inner.clone()
}
}
}
/// HashMap values iterator.
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Values<'a, K: 'a, V: 'a> {
inner: Map<Iter<'a, K, V>, fn((&'a K, &'a V)) -> &'a V>
}
// FIXME(#19839) Remove in favor of `#[derive(Clone)]`
impl<'a, K, V> Clone for Values<'a, K, V> {
fn clone(&self) -> Values<'a, K, V> {
Values {
inner: self.inner.clone()
}
}
}
/// HashMap drain iterator.
#[unstable(feature = "std_misc",
reason = "matches collection reform specification, waiting for dust to settle")]
pub struct Drain<'a, K: 'a, V: 'a> {
inner: iter::Map<table::Drain<'a, K, V>, fn((SafeHash, K, V)) -> (K, V)>
}
/// A view into a single occupied location in a HashMap.
#[stable(feature = "rust1", since = "1.0.0")]
pub struct OccupiedEntry<'a, K: 'a, V: 'a> {
elem: FullBucket<K, V, &'a mut RawTable<K, V>>,
}
/// A view into a single empty location in a HashMap.
#[stable(feature = "rust1", since = "1.0.0")]
pub struct VacantEntry<'a, K: 'a, V: 'a> {
hash: SafeHash,
key: K,
elem: VacantEntryState<K, V, &'a mut RawTable<K, V>>,
}
/// A view into a single location in a map, which may be vacant or occupied.
#[stable(feature = "rust1", since = "1.0.0")]
pub enum Entry<'a, K: 'a, V: 'a> {
/// An occupied Entry.
#[stable(feature = "rust1", since = "1.0.0")]
Occupied(OccupiedEntry<'a, K, V>),
/// A vacant Entry.
#[stable(feature = "rust1", since = "1.0.0")]
Vacant(VacantEntry<'a, K, V>),
}
/// Possible states of a VacantEntry.
enum VacantEntryState<K, V, M> {
/// The index is occupied, but the key to insert has precedence,
/// and will kick the current one out on insertion.
NeqElem(FullBucket<K, V, M>, usize),
/// The index is genuinely vacant.
NoElem(EmptyBucket<K, V, M>),
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V, S> IntoIterator for &'a HashMap<K, V, S>
where K: Eq + Hash, S: HashState
{
type Item = (&'a K, &'a V);
type IntoIter = Iter<'a, K, V>;
fn into_iter(self) -> Iter<'a, K, V> {
self.iter()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V, S> IntoIterator for &'a mut HashMap<K, V, S>
where K: Eq + Hash, S: HashState
{
type Item = (&'a K, &'a mut V);
type IntoIter = IterMut<'a, K, V>;
fn into_iter(mut self) -> IterMut<'a, K, V> {
self.iter_mut()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V, S> IntoIterator for HashMap<K, V, S>
where K: Eq + Hash, S: HashState
{
type Item = (K, V);
type IntoIter = IntoIter<K, V>;
/// 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.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut map = HashMap::new();
/// map.insert("a", 1);
/// map.insert("b", 2);
/// map.insert("c", 3);
///
/// // Not possible with .iter()
/// let vec: Vec<(&str, isize)> = map.into_iter().collect();
/// ```
fn into_iter(self) -> IntoIter<K, V> {
fn last_two<A, B, C>((_, b, c): (A, B, C)) -> (B, C) { (b, c) }
let last_two: fn((SafeHash, K, V)) -> (K, V) = last_two;
IntoIter {
inner: self.table.into_iter().map(last_two)
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V> Iterator for Iter<'a, K, V> {
type Item = (&'a K, &'a V);
#[inline] fn next(&mut self) -> Option<(&'a K, &'a V)> { self.inner.next() }
#[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V> ExactSizeIterator for Iter<'a, K, V> {
#[inline] fn len(&self) -> usize { self.inner.len() }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V> Iterator for IterMut<'a, K, V> {
type Item = (&'a K, &'a mut V);
#[inline] fn next(&mut self) -> Option<(&'a K, &'a mut V)> { self.inner.next() }
#[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V> ExactSizeIterator for IterMut<'a, K, V> {
#[inline] fn len(&self) -> usize { self.inner.len() }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V> Iterator for IntoIter<K, V> {
type Item = (K, V);
#[inline] fn next(&mut self) -> Option<(K, V)> { self.inner.next() }
#[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V> ExactSizeIterator for IntoIter<K, V> {
#[inline] fn len(&self) -> usize { self.inner.len() }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V> Iterator for Keys<'a, K, V> {
type Item = &'a K;
#[inline] fn next(&mut self) -> Option<(&'a K)> { self.inner.next() }
#[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V> ExactSizeIterator for Keys<'a, K, V> {
#[inline] fn len(&self) -> usize { self.inner.len() }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V> Iterator for Values<'a, K, V> {
type Item = &'a V;
#[inline] fn next(&mut self) -> Option<(&'a V)> { self.inner.next() }
#[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V> ExactSizeIterator for Values<'a, K, V> {
#[inline] fn len(&self) -> usize { self.inner.len() }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V> Iterator for Drain<'a, K, V> {
type Item = (K, V);
#[inline] fn next(&mut self) -> Option<(K, V)> { self.inner.next() }
#[inline] fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V> ExactSizeIterator for Drain<'a, K, V> {
#[inline] fn len(&self) -> usize { self.inner.len() }
}
impl<'a, K, V> Entry<'a, K, V> {
#[unstable(feature = "std_misc",
reason = "will soon be replaced by or_insert")]
#[deprecated(since = "1.0",
reason = "replaced with more ergonomic `or_insert` and `or_insert_with`")]
/// Returns a mutable reference to the entry if occupied, or the VacantEntry if vacant
pub fn get(self) -> Result<&'a mut V, VacantEntry<'a, K, V>> {
match self {
Occupied(entry) => Ok(entry.into_mut()),
Vacant(entry) => Err(entry),
}
}
#[stable(feature = "rust1", since = "1.0.0")]
/// Ensures a value is in the entry by inserting the default if empty, and returns
/// a mutable reference to the value in the entry.
pub fn or_insert(self, default: V) -> &'a mut V {
match self {
Occupied(entry) => entry.into_mut(),
Vacant(entry) => entry.insert(default),
}
}
#[stable(feature = "rust1", since = "1.0.0")]
/// Ensures a value is in the entry by inserting the result of the default function if empty,
/// and returns a mutable reference to the value in the entry.
pub fn or_insert_with<F: FnOnce() -> V>(self, default: F) -> &'a mut V {
match self {
Occupied(entry) => entry.into_mut(),
Vacant(entry) => entry.insert(default()),
}
}
}
impl<'a, K, V> OccupiedEntry<'a, K, V> {
/// Gets a reference to the value in the entry.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn get(&self) -> &V {
self.elem.read().1
}
/// Gets a mutable reference to the value in the entry.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn get_mut(&mut self) -> &mut V {
self.elem.read_mut().1
}
/// Converts the OccupiedEntry into a mutable reference to the value in the entry
/// with a lifetime bound to the map itself
#[stable(feature = "rust1", since = "1.0.0")]
pub fn into_mut(self) -> &'a mut V {
self.elem.into_mut_refs().1
}
/// Sets the value of the entry, and returns the entry's old value
#[stable(feature = "rust1", since = "1.0.0")]
pub fn insert(&mut self, mut value: V) -> V {
let old_value = self.get_mut();
mem::swap(&mut value, old_value);
value
}
/// Takes the value out of the entry, and returns it
#[stable(feature = "rust1", since = "1.0.0")]
pub fn remove(self) -> V {
pop_internal(self.elem).1
}
}
impl<'a, K: 'a, V: 'a> VacantEntry<'a, K, V> {
/// Sets the value of the entry with the VacantEntry's key,
/// and returns a mutable reference to it
#[stable(feature = "rust1", since = "1.0.0")]
pub fn insert(self, value: V) -> &'a mut V {
match self.elem {
NeqElem(bucket, ib) => {
robin_hood(bucket, ib, self.hash, self.key, value)
}
NoElem(bucket) => {
bucket.put(self.hash, self.key, value).into_mut_refs().1
}
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V, S> FromIterator<(K, V)> for HashMap<K, V, S>
where K: Eq + Hash, S: HashState + Default
{
fn from_iter<T: IntoIterator<Item=(K, V)>>(iterable: T) -> HashMap<K, V, S> {
let iter = iterable.into_iter();
let lower = iter.size_hint().0;
let mut map = HashMap::with_capacity_and_hash_state(lower,
Default::default());
map.extend(iter);
map
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V, S> Extend<(K, V)> for HashMap<K, V, S>
where K: Eq + Hash, S: HashState
{
fn extend<T: IntoIterator<Item=(K, V)>>(&mut self, iter: T) {
for (k, v) in iter {
self.insert(k, v);
}
}
}
/// `RandomState` is the default state for `HashMap` types.
///
/// A particular instance `RandomState` will create the same instances of
/// `Hasher`, but the hashers created by two different `RandomState`
/// instances are unlikely to produce the same result for the same values.
#[derive(Clone)]
#[unstable(feature = "std_misc",
reason = "hashing an hash maps may be altered")]
pub struct RandomState {
k0: u64,
k1: u64,
}
#[unstable(feature = "std_misc",
reason = "hashing an hash maps may be altered")]
impl RandomState {
/// Constructs a new `RandomState` that is initialized with random keys.
#[inline]
#[allow(deprecated)]
pub fn new() -> RandomState {
let mut r = rand::thread_rng();
RandomState { k0: r.gen(), k1: r.gen() }
}
}
#[unstable(feature = "std_misc",
reason = "hashing an hash maps may be altered")]
impl HashState for RandomState {
type Hasher = SipHasher;
#[inline]
fn hasher(&self) -> SipHasher {
SipHasher::new_with_keys(self.k0, self.k1)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl Default for RandomState {
#[inline]
fn default() -> RandomState {
RandomState::new()
}
}
#[cfg(test)]
mod test_map {
use prelude::v1::*;
use super::HashMap;
use super::Entry::{Occupied, Vacant};
use iter::{range_inclusive, repeat};
use cell::RefCell;
use rand::{thread_rng, Rng};
#[test]
fn test_create_capacity_zero() {
let mut m = HashMap::with_capacity(0);
assert!(m.insert(1, 1).is_none());
assert!(m.contains_key(&1));
assert!(!m.contains_key(&0));
}
#[test]
fn test_insert() {
let mut m = HashMap::new();
assert_eq!(m.len(), 0);
assert!(m.insert(1, 2).is_none());
assert_eq!(m.len(), 1);
assert!(m.insert(2, 4).is_none());
assert_eq!(m.len(), 2);
assert_eq!(*m.get(&1).unwrap(), 2);
assert_eq!(*m.get(&2).unwrap(), 4);
}
thread_local! { static DROP_VECTOR: RefCell<Vec<isize>> = RefCell::new(Vec::new()) }
#[derive(Hash, PartialEq, Eq)]
struct Dropable {
k: usize
}
impl Dropable {
fn new(k: usize) -> Dropable {
DROP_VECTOR.with(|slot| {
slot.borrow_mut()[k] += 1;
});
Dropable { k: k }
}
}
impl Drop for Dropable {
fn drop(&mut self) {
DROP_VECTOR.with(|slot| {
slot.borrow_mut()[self.k] -= 1;
});
}
}
impl Clone for Dropable {
fn clone(&self) -> Dropable {
Dropable::new(self.k)
}
}
#[test]
fn test_drops() {
DROP_VECTOR.with(|slot| {
*slot.borrow_mut() = repeat(0).take(200).collect();
});
{
let mut m = HashMap::new();
DROP_VECTOR.with(|v| {
for i in 0..200 {
assert_eq!(v.borrow()[i], 0);
}
});
for i in 0..100 {
let d1 = Dropable::new(i);
let d2 = Dropable::new(i+100);
m.insert(d1, d2);
}
DROP_VECTOR.with(|v| {
for i in 0..200 {
assert_eq!(v.borrow()[i], 1);
}
});
for i in 0..50 {
let k = Dropable::new(i);
let v = m.remove(&k);
assert!(v.is_some());
DROP_VECTOR.with(|v| {
assert_eq!(v.borrow()[i], 1);
assert_eq!(v.borrow()[i+100], 1);
});
}
DROP_VECTOR.with(|v| {
for i in 0..50 {
assert_eq!(v.borrow()[i], 0);
assert_eq!(v.borrow()[i+100], 0);
}
for i in 50..100 {
assert_eq!(v.borrow()[i], 1);
assert_eq!(v.borrow()[i+100], 1);
}
});
}
DROP_VECTOR.with(|v| {
for i in 0..200 {
assert_eq!(v.borrow()[i], 0);
}
});
}
#[test]
fn test_move_iter_drops() {
DROP_VECTOR.with(|v| {
*v.borrow_mut() = repeat(0).take(200).collect();
});
let hm = {
let mut hm = HashMap::new();
DROP_VECTOR.with(|v| {
for i in 0..200 {
assert_eq!(v.borrow()[i], 0);
}
});
for i in 0..100 {
let d1 = Dropable::new(i);
let d2 = Dropable::new(i+100);
hm.insert(d1, d2);
}
DROP_VECTOR.with(|v| {
for i in 0..200 {
assert_eq!(v.borrow()[i], 1);
}
});
hm
};
// By the way, ensure that cloning doesn't screw up the dropping.
drop(hm.clone());
{
let mut half = hm.into_iter().take(50);
DROP_VECTOR.with(|v| {
for i in 0..200 {
assert_eq!(v.borrow()[i], 1);
}
});
for _ in half.by_ref() {}
DROP_VECTOR.with(|v| {
let nk = (0..100).filter(|&i| {
v.borrow()[i] == 1
}).count();
let nv = (0..100).filter(|&i| {
v.borrow()[i+100] == 1
}).count();
assert_eq!(nk, 50);
assert_eq!(nv, 50);
});
};
DROP_VECTOR.with(|v| {
for i in 0..200 {
assert_eq!(v.borrow()[i], 0);
}
});
}
#[test]
fn test_empty_pop() {
let mut m: HashMap<isize, bool> = HashMap::new();
assert_eq!(m.remove(&0), None);
}
#[test]
fn test_lots_of_insertions() {
let mut m = HashMap::new();
// Try this a few times to make sure we never screw up the hashmap's
// internal state.
for _ in 0..10 {
assert!(m.is_empty());
for i in range_inclusive(1, 1000) {
assert!(m.insert(i, i).is_none());
for j in range_inclusive(1, i) {
let r = m.get(&j);
assert_eq!(r, Some(&j));
}
for j in range_inclusive(i+1, 1000) {
let r = m.get(&j);
assert_eq!(r, None);
}
}
for i in range_inclusive(1001, 2000) {
assert!(!m.contains_key(&i));
}
// remove forwards
for i in range_inclusive(1, 1000) {
assert!(m.remove(&i).is_some());
for j in range_inclusive(1, i) {
assert!(!m.contains_key(&j));
}
for j in range_inclusive(i+1, 1000) {
assert!(m.contains_key(&j));
}
}
for i in range_inclusive(1, 1000) {
assert!(!m.contains_key(&i));
}
for i in range_inclusive(1, 1000) {
assert!(m.insert(i, i).is_none());
}
// remove backwards
for i in (1..1001).rev() {
assert!(m.remove(&i).is_some());
for j in range_inclusive(i, 1000) {
assert!(!m.contains_key(&j));
}
for j in range_inclusive(1, i-1) {
assert!(m.contains_key(&j));
}
}
}
}
#[test]
fn test_find_mut() {
let mut m = HashMap::new();
assert!(m.insert(1, 12).is_none());
assert!(m.insert(2, 8).is_none());
assert!(m.insert(5, 14).is_none());
let new = 100;
match m.get_mut(&5) {
None => panic!(), Some(x) => *x = new
}
assert_eq!(m.get(&5), Some(&new));
}
#[test]
fn test_insert_overwrite() {
let mut m = HashMap::new();
assert!(m.insert(1, 2).is_none());
assert_eq!(*m.get(&1).unwrap(), 2);
assert!(!m.insert(1, 3).is_none());
assert_eq!(*m.get(&1).unwrap(), 3);
}
#[test]
fn test_insert_conflicts() {
let mut m = HashMap::with_capacity(4);
assert!(m.insert(1, 2).is_none());
assert!(m.insert(5, 3).is_none());
assert!(m.insert(9, 4).is_none());
assert_eq!(*m.get(&9).unwrap(), 4);
assert_eq!(*m.get(&5).unwrap(), 3);
assert_eq!(*m.get(&1).unwrap(), 2);
}
#[test]
fn test_conflict_remove() {
let mut m = HashMap::with_capacity(4);
assert!(m.insert(1, 2).is_none());
assert_eq!(*m.get(&1).unwrap(), 2);
assert!(m.insert(5, 3).is_none());
assert_eq!(*m.get(&1).unwrap(), 2);
assert_eq!(*m.get(&5).unwrap(), 3);
assert!(m.insert(9, 4).is_none());
assert_eq!(*m.get(&1).unwrap(), 2);
assert_eq!(*m.get(&5).unwrap(), 3);
assert_eq!(*m.get(&9).unwrap(), 4);
assert!(m.remove(&1).is_some());
assert_eq!(*m.get(&9).unwrap(), 4);
assert_eq!(*m.get(&5).unwrap(), 3);
}
#[test]
fn test_is_empty() {
let mut m = HashMap::with_capacity(4);
assert!(m.insert(1, 2).is_none());
assert!(!m.is_empty());
assert!(m.remove(&1).is_some());
assert!(m.is_empty());
}
#[test]
fn test_pop() {
let mut m = HashMap::new();
m.insert(1, 2);
assert_eq!(m.remove(&1), Some(2));
assert_eq!(m.remove(&1), None);
}
#[test]
fn test_iterate() {
let mut m = HashMap::with_capacity(4);
for i in 0..32 {
assert!(m.insert(i, i*2).is_none());
}
assert_eq!(m.len(), 32);
let mut observed: u32 = 0;
for (k, v) in &m {
assert_eq!(*v, *k * 2);
observed |= 1 << *k;
}
assert_eq!(observed, 0xFFFF_FFFF);
}
#[test]
fn test_keys() {
let vec = vec![(1, 'a'), (2, 'b'), (3, 'c')];
let map: HashMap<_, _> = vec.into_iter().collect();
let keys: Vec<_> = map.keys().cloned().collect();
assert_eq!(keys.len(), 3);
assert!(keys.contains(&1));
assert!(keys.contains(&2));
assert!(keys.contains(&3));
}
#[test]
fn test_values() {
let vec = vec![(1, 'a'), (2, 'b'), (3, 'c')];
let map: HashMap<_, _> = vec.into_iter().collect();
let values: Vec<_> = map.values().cloned().collect();
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.get(&1).is_none());
m.insert(1, 2);
match m.get(&1) {
None => panic!(),
Some(v) => assert_eq!(*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_show() {
let mut map = HashMap::new();
let empty: HashMap<i32, i32> = HashMap::new();
map.insert(1, 2);
map.insert(3, 4);
let map_str = format!("{:?}", map);
assert!(map_str == "{1: 2, 3: 4}" ||
map_str == "{3: 4, 1: 2}");
assert_eq!(format!("{:?}", empty), "{}");
}
#[test]
fn test_expand() {
let mut m = HashMap::new();
assert_eq!(m.len(), 0);
assert!(m.is_empty());
let mut i = 0;
let old_cap = m.table.capacity();
while old_cap == m.table.capacity() {
m.insert(i, i);
i += 1;
}
assert_eq!(m.len(), i);
assert!(!m.is_empty());
}
#[test]
fn test_behavior_resize_policy() {
let mut m = HashMap::new();
assert_eq!(m.len(), 0);
assert_eq!(m.table.capacity(), 0);
assert!(m.is_empty());
m.insert(0, 0);
m.remove(&0);
assert!(m.is_empty());
let initial_cap = m.table.capacity();
m.reserve(initial_cap);
let cap = m.table.capacity();
assert_eq!(cap, initial_cap * 2);
let mut i = 0;
for _ in 0..cap * 3 / 4 {
m.insert(i, i);
i += 1;
}
// three quarters full
assert_eq!(m.len(), i);
assert_eq!(m.table.capacity(), cap);
for _ in 0..cap / 4 {
m.insert(i, i);
i += 1;
}
// half full
let new_cap = m.table.capacity();
assert_eq!(new_cap, cap * 2);
for _ in 0..cap / 2 - 1 {
i -= 1;
m.remove(&i);
assert_eq!(m.table.capacity(), new_cap);
}
// A little more than one quarter full.
m.shrink_to_fit();
assert_eq!(m.table.capacity(), cap);
// again, a little more than half full
for _ in 0..cap / 2 - 1 {
i -= 1;
m.remove(&i);
}
m.shrink_to_fit();
assert_eq!(m.len(), i);
assert!(!m.is_empty());
assert_eq!(m.table.capacity(), initial_cap);
}
#[test]
fn test_reserve_shrink_to_fit() {
let mut m = HashMap::new();
m.insert(0, 0);
m.remove(&0);
assert!(m.capacity() >= m.len());
for i in 0..128 {
m.insert(i, i);
}
m.reserve(256);
let usable_cap = m.capacity();
for i in 128..(128 + 256) {
m.insert(i, i);
assert_eq!(m.capacity(), usable_cap);
}
for i in 100..(128 + 256) {
assert_eq!(m.remove(&i), Some(i));
}
m.shrink_to_fit();
assert_eq!(m.len(), 100);
assert!(!m.is_empty());
assert!(m.capacity() >= m.len());
for i in 0..100 {
assert_eq!(m.remove(&i), Some(i));
}
m.shrink_to_fit();
m.insert(0, 0);
assert_eq!(m.len(), 1);
assert!(m.capacity() >= m.len());
assert_eq!(m.remove(&0), Some(0));
}
#[test]
fn test_from_iter() {
let xs = [(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)];
let map: HashMap<_, _> = xs.iter().cloned().collect();
for &(k, v) in &xs {
assert_eq!(map.get(&k), Some(&v));
}
}
#[test]
fn test_size_hint() {
let xs = [(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)];
let map: HashMap<_, _> = xs.iter().cloned().collect();
let mut iter = map.iter();
for _ in iter.by_ref().take(3) {}
assert_eq!(iter.size_hint(), (3, Some(3)));
}
#[test]
fn test_iter_len() {
let xs = [(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)];
let map: HashMap<_, _> = xs.iter().cloned().collect();
let mut iter = map.iter();
for _ in iter.by_ref().take(3) {}
assert_eq!(iter.len(), 3);
}
#[test]
fn test_mut_size_hint() {
let xs = [(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)];
let mut map: HashMap<_, _> = xs.iter().cloned().collect();
let mut iter = map.iter_mut();
for _ in iter.by_ref().take(3) {}
assert_eq!(iter.size_hint(), (3, Some(3)));
}
#[test]
fn test_iter_mut_len() {
let xs = [(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)];
let mut map: HashMap<_, _> = xs.iter().cloned().collect();
let mut iter = map.iter_mut();
for _ in iter.by_ref().take(3) {}
assert_eq!(iter.len(), 3);
}
#[test]
fn test_index() {
let mut map = HashMap::new();
map.insert(1, 2);
map.insert(2, 1);
map.insert(3, 4);
assert_eq!(map[&2], 1);
}
#[test]
#[should_panic]
fn test_index_nonexistent() {
let mut map = HashMap::new();
map.insert(1, 2);
map.insert(2, 1);
map.insert(3, 4);
map[&4];
}
#[test]
fn test_entry(){
let xs = [(1, 10), (2, 20), (3, 30), (4, 40), (5, 50), (6, 60)];
let mut map: HashMap<_, _> = xs.iter().cloned().collect();
// Existing key (insert)
match map.entry(1) {
Vacant(_) => unreachable!(),
Occupied(mut view) => {
assert_eq!(view.get(), &10);
assert_eq!(view.insert(100), 10);
}
}
assert_eq!(map.get(&1).unwrap(), &100);
assert_eq!(map.len(), 6);
// Existing key (update)
match map.entry(2) {
Vacant(_) => unreachable!(),
Occupied(mut view) => {
let v = view.get_mut();
let new_v = (*v) * 10;
*v = new_v;
}
}
assert_eq!(map.get(&2).unwrap(), &200);
assert_eq!(map.len(), 6);
// Existing key (take)
match map.entry(3) {
Vacant(_) => unreachable!(),
Occupied(view) => {
assert_eq!(view.remove(), 30);
}
}
assert_eq!(map.get(&3), None);
assert_eq!(map.len(), 5);
// Inexistent key (insert)
match map.entry(10) {
Occupied(_) => unreachable!(),
Vacant(view) => {
assert_eq!(*view.insert(1000), 1000);
}
}
assert_eq!(map.get(&10).unwrap(), &1000);
assert_eq!(map.len(), 6);
}
#[test]
fn test_entry_take_doesnt_corrupt() {
#![allow(deprecated)] //rand
// Test for #19292
fn check(m: &HashMap<isize, ()>) {
for k in m.keys() {
assert!(m.contains_key(k),
"{} is in keys() but not in the map?", k);
}
}
let mut m = HashMap::new();
let mut rng = thread_rng();
// Populate the map with some items.
for _ in 0..50 {
let x = rng.gen_range(-10, 10);
m.insert(x, ());
}
for i in 0..1000 {
let x = rng.gen_range(-10, 10);
match m.entry(x) {
Vacant(_) => {},
Occupied(e) => {
println!("{}: remove {}", i, x);
e.remove();
},
}
check(&m);
}
}
}
Reference in New Issue View Git Blame Copy Permalink