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Diffstat (limited to 'servo/components/hashglobe/src/hash_map.rs')
| -rw-r--r-- | servo/components/hashglobe/src/hash_map.rs | 3087 |
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diff --git a/servo/components/hashglobe/src/hash_map.rs b/servo/components/hashglobe/src/hash_map.rs new file mode 100644 index 0000000000..d2893627e1 --- /dev/null +++ b/servo/components/hashglobe/src/hash_map.rs @@ -0,0 +1,3087 @@ +// 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::VacantEntryState::*; + +use std::borrow::Borrow; +use std::cmp::max; +use std::fmt::{self, Debug}; +#[allow(deprecated)] +use std::hash::{BuildHasher, Hash}; +use std::iter::FromIterator; +use std::mem::{self, replace}; +use std::ops::{Deref, Index}; + +use super::table::BucketState::{Empty, Full}; +use super::table::{self, Bucket, EmptyBucket, FullBucket, FullBucketMut, RawTable, SafeHash}; + +use crate::FailedAllocationError; + +const MIN_NONZERO_RAW_CAPACITY: usize = 32; // must be a power of two + +/// The default behavior of HashMap implements a maximum load factor of 90.9%. +#[derive(Clone)] +struct DefaultResizePolicy; + +impl DefaultResizePolicy { + fn new() -> DefaultResizePolicy { + DefaultResizePolicy + } + + /// A hash map's "capacity" is the number of elements it can hold without + /// being resized. Its "raw capacity" is the number of slots required to + /// provide that capacity, accounting for maximum loading. The raw capacity + /// is always zero or a power of two. + #[inline] + fn raw_capacity(&self, len: usize) -> usize { + if len == 0 { + 0 + } else { + // 1. Account for loading: `raw_capacity >= len * 1.1`. + // 2. Ensure it is a power of two. + // 3. Ensure it is at least the minimum size. + let mut raw_cap = len * 11 / 10; + assert!(raw_cap >= len, "raw_cap overflow"); + raw_cap = raw_cap + .checked_next_power_of_two() + .expect("raw_capacity overflow"); + raw_cap = max(MIN_NONZERO_RAW_CAPACITY, raw_cap); + raw_cap + } + } + + /// The capacity of the given raw capacity. + #[inline] + fn capacity(&self, raw_cap: usize) -> usize { + // This doesn't have to be checked for overflow since allocation size + // in bytes will overflow earlier than multiplication by 10. + // + // As per https://github.com/rust-lang/rust/pull/30991 this is updated + // to be: (raw_cap * den + den - 1) / num + (raw_cap * 10 + 10 - 1) / 11 + } +} + +// 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 +// +// Adaptive early resizing +// ---------------------- +// To protect against degenerate performance scenarios (including DOS attacks), +// the implementation includes an adaptive behavior that can resize the map +// early (before its capacity is exceeded) when suspiciously long probe sequences +// are encountered. +// +// With this algorithm in place it would be possible to turn a CPU attack into +// a memory attack due to the aggressive resizing. To prevent that the +// adaptive behavior only triggers when the map is at least half full. +// This reduces the effectiveness of the algorithm but also makes it completely safe. +// +// The previous safety measure also prevents degenerate interactions with +// really bad quality hash algorithms that can make normal inputs look like a +// DOS attack. +// +const DISPLACEMENT_THRESHOLD: usize = 128; +// +// The threshold of 128 is chosen to minimize the chance of exceeding it. +// In particular, we want that chance to be less than 10^-8 with a load of 90%. +// For displacement, the smallest constant that fits our needs is 90, +// so we round that up to 128. +// +// At a load factor of α, the odds of finding the target bucket after exactly n +// unsuccessful probes[1] are +// +// Pr_α{displacement = n} = +// (1 - α) / α * ∑_{k≥1} e^(-kα) * (kα)^(k+n) / (k + n)! * (1 - kα / (k + n + 1)) +// +// We use this formula to find the probability of triggering the adaptive behavior +// +// Pr_0.909{displacement > 128} = 1.601 * 10^-11 +// +// 1. Alfredo Viola (2005). Distributional analysis of Robin Hood linear probing +// hashing with buckets. + +/// A hash map implemented with linear probing and Robin Hood bucket stealing. +/// +/// By default, `HashMap` uses a hashing algorithm selected to provide +/// resistance against HashDoS attacks. The algorithm is randomly seeded, and a +/// reasonable best-effort is made to generate this seed from a high quality, +/// secure source of randomness provided by the host without blocking the +/// program. Because of this, the randomness of the seed depends on the output +/// quality of the system's random number generator when the seed is created. +/// In particular, seeds generated when the system's entropy pool is abnormally +/// low such as during system boot may be of a lower quality. +/// +/// The default hashing algorithm is currently SipHash 1-3, though this is +/// subject to change at any point in the future. While its performance is very +/// competitive for medium sized keys, other hashing algorithms will outperform +/// it for small keys such as integers as well as large keys such as long +/// strings, though those algorithms will typically *not* protect against +/// attacks such as HashDoS. +/// +/// The hashing algorithm can be replaced on a per-`HashMap` basis using the +/// [`default`], [`with_hasher`], and [`with_capacity_and_hasher`] methods. Many +/// alternative algorithms are available on crates.io, such as the [`fnv`] crate. +/// +/// 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); +/// } +/// ``` +/// +/// `HashMap` also implements an [`Entry API`](#method.entry), which allows +/// for more complex methods of getting, setting, updating and removing keys and +/// their values: +/// +/// ``` +/// use std::collections::HashMap; +/// +/// // type inference lets us omit an explicit type signature (which +/// // would be `HashMap<&str, u8>` in this example). +/// let mut player_stats = HashMap::new(); +/// +/// fn random_stat_buff() -> u8 { +/// // could actually return some random value here - let's just return +/// // some fixed value for now +/// 42 +/// } +/// +/// // insert a key only if it doesn't already exist +/// player_stats.entry("health").or_insert(100); +/// +/// // insert a key using a function that provides a new value only if it +/// // doesn't already exist +/// player_stats.entry("defence").or_insert_with(random_stat_buff); +/// +/// // update a key, guarding against the key possibly not being set +/// let stat = player_stats.entry("attack").or_insert(100); +/// *stat += random_stat_buff(); +/// ``` +/// +/// The easiest way to use `HashMap` with a custom type as key is to derive [`Eq`] and [`Hash`]. +/// We must also derive [`PartialEq`]. +/// +/// [`Eq`]: ../../std/cmp/trait.Eq.html +/// [`Hash`]: ../../std/hash/trait.Hash.html +/// [`PartialEq`]: ../../std/cmp/trait.PartialEq.html +/// [`RefCell`]: ../../std/cell/struct.RefCell.html +/// [`Cell`]: ../../std/cell/struct.Cell.html +/// [`default`]: #method.default +/// [`with_hasher`]: #method.with_hasher +/// [`with_capacity_and_hasher`]: #method.with_capacity_and_hasher +/// [`fnv`]: https://crates.io/crates/fnv +/// +/// ``` +/// 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); +/// } +/// ``` +/// +/// A `HashMap` with fixed list of elements can be initialized from an array: +/// +/// ``` +/// use std::collections::HashMap; +/// +/// fn main() { +/// let timber_resources: HashMap<&str, i32> = +/// [("Norway", 100), +/// ("Denmark", 50), +/// ("Iceland", 10)] +/// .iter().cloned().collect(); +/// // use the values stored in map +/// } +/// ``` + +#[derive(Clone)] +pub struct HashMap<K, V, S = RandomState> { + // All hashes are keyed on these values, to prevent hash collision attacks. + hash_builder: S, + + table: RawTable<K, V>, + + resize_policy: DefaultResizePolicy, +} + +/// Search for a pre-hashed key. +#[inline] +fn search_hashed<K, V, M, F>(table: M, hash: SafeHash, mut is_match: F) -> InternalEntry<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 behavior when Bucket::new gets the raw bucket in this + // case, immediately return the appropriate search result. + if table.capacity() == 0 { + return InternalEntry::TableIsEmpty; + } + + let size = table.size(); + let mut probe = Bucket::new(table, hash); + let mut displacement = 0; + + loop { + let full = match probe.peek() { + Empty(bucket) => { + // Found a hole! + return InternalEntry::Vacant { + hash, + elem: NoElem(bucket, displacement), + }; + }, + Full(bucket) => bucket, + }; + + let probe_displacement = full.displacement(); + + if probe_displacement < displacement { + // Found a luckier bucket than me. + // We can finish the search early if we hit any bucket + // with a lower distance to initial bucket than we've probed. + return InternalEntry::Vacant { + hash, + elem: NeqElem(full, probe_displacement), + }; + } + + // 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 InternalEntry::Occupied { elem: full }; + } + } + displacement += 1; + probe = full.next(); + debug_assert!(displacement <= size); + } +} + +fn pop_internal<K, V>(starting_bucket: FullBucketMut<K, V>) -> (K, V, &mut RawTable<K, V>) { + let (empty, retkey, retval) = starting_bucket.take(); + let mut gap = match empty.gap_peek() { + Ok(b) => b, + Err(b) => return (retkey, retval, b.into_table()), + }; + + while gap.full().displacement() != 0 { + gap = match gap.shift() { + Ok(b) => b, + Err(b) => { + return (retkey, retval, b.into_table()); + }, + }; + } + + // Now we've done all our shifting. Return the value we grabbed earlier. + (retkey, retval, gap.into_table()) +} + +/// Perform robin hood bucket stealing at the given `bucket`. You must +/// also pass that bucket's displacement so we don't have to recalculate it. +/// +/// `hash`, `key`, and `val` are the elements to "robin hood" into the hashtable. +fn robin_hood<'a, K: 'a, V: 'a>( + bucket: FullBucketMut<'a, K, V>, + mut displacement: usize, + mut hash: SafeHash, + mut key: K, + mut val: V, +) -> FullBucketMut<'a, K, V> { + let size = bucket.table().size(); + let raw_capacity = bucket.table().capacity(); + // There can be at most `size - dib` buckets to displace, because + // in the worst case, there are `size` elements and we already are + // `displacement` buckets away from the initial one. + let idx_end = (bucket.index() + size - bucket.displacement()) % raw_capacity; + // Save the *starting point*. + let mut bucket = bucket.stash(); + + loop { + let (old_hash, old_key, old_val) = bucket.replace(hash, key, val); + hash = old_hash; + key = old_key; + val = old_val; + + loop { + displacement += 1; + let probe = bucket.next(); + debug_assert_ne!(probe.index(), idx_end); + + let full_bucket = match probe.peek() { + Empty(bucket) => { + // Found a hole! + let bucket = bucket.put(hash, key, val); + // Now that it's stolen, just read the value's pointer + // right out of the table! Go back to the *starting point*. + // + // This use of `into_table` is misleading. It turns the + // bucket, which is a FullBucket on top of a + // FullBucketMut, into just one FullBucketMut. The "table" + // refers to the inner FullBucketMut in this context. + return bucket.into_table(); + }, + Full(bucket) => bucket, + }; + + let probe_displacement = full_bucket.displacement(); + + bucket = full_bucket; + + // Robin hood! Steal the spot. + if probe_displacement < displacement { + displacement = probe_displacement; + break; + } + } + } +} + +impl<K, V, S> HashMap<K, V, S> +where + K: Eq + Hash, + S: BuildHasher, +{ + fn make_hash<X: ?Sized>(&self, x: &X) -> SafeHash + where + X: Hash, + { + table::make_hash(&self.hash_builder, 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. + #[inline] + fn search<'a, Q: ?Sized>(&'a self, q: &Q) -> InternalEntry<K, V, &'a RawTable<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())) + } + + #[inline] + fn search_mut<'a, Q: ?Sized>(&'a mut self, q: &Q) -> InternalEntry<K, V, &'a mut RawTable<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())) + } + + // The caller should ensure that invariants by Robin Hood Hashing hold + // and that there's space in the underlying table. + fn insert_hashed_ordered(&mut self, hash: SafeHash, k: K, v: V) { + let mut buckets = Bucket::new(&mut self.table, hash); + let start_index = buckets.index(); + + loop { + // 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(); + debug_assert_ne!(buckets.index(), start_index); + } + } +} + +impl<K, V, S> HashMap<K, V, S> +where + K: Eq + Hash, + S: BuildHasher, +{ + /// Creates an empty `HashMap` which will use the given hash builder to hash + /// keys. + /// + /// The created map has the default initial capacity. + /// + /// Warning: `hash_builder` 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 + /// + /// ``` + /// use std::collections::HashMap; + /// use std::collections::hash_map::RandomState; + /// + /// let s = RandomState::new(); + /// let mut map = HashMap::with_hasher(s); + /// map.insert(1, 2); + /// ``` + #[inline] + pub fn try_with_hasher(hash_builder: S) -> Result<HashMap<K, V, S>, FailedAllocationError> { + Ok(HashMap { + hash_builder, + resize_policy: DefaultResizePolicy::new(), + table: RawTable::new(0)?, + }) + } + + #[inline] + pub fn with_hasher(hash_builder: S) -> HashMap<K, V, S> { + Self::try_with_hasher(hash_builder).unwrap() + } + + /// Creates an empty `HashMap` with the specified capacity, using `hash_builder` + /// to hash the keys. + /// + /// The hash map will be able to hold at least `capacity` elements without + /// reallocating. If `capacity` is 0, the hash map will not allocate. + /// + /// Warning: `hash_builder` 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 + /// + /// ``` + /// use std::collections::HashMap; + /// use std::collections::hash_map::RandomState; + /// + /// let s = RandomState::new(); + /// let mut map = HashMap::with_capacity_and_hasher(10, s); + /// map.insert(1, 2); + /// ``` + #[inline] + pub fn try_with_capacity_and_hasher( + capacity: usize, + hash_builder: S, + ) -> Result<HashMap<K, V, S>, FailedAllocationError> { + let resize_policy = DefaultResizePolicy::new(); + let raw_cap = resize_policy.raw_capacity(capacity); + Ok(HashMap { + hash_builder, + resize_policy, + table: RawTable::new(raw_cap)?, + }) + } + + pub fn with_capacity_and_hasher(capacity: usize, hash_builder: S) -> HashMap<K, V, S> { + Self::try_with_capacity_and_hasher(capacity, hash_builder).unwrap() + } + + /// Returns a reference to the map's [`BuildHasher`]. + /// + /// [`BuildHasher`]: ../../std/hash/trait.BuildHasher.html + pub fn hasher(&self) -> &S { + &self.hash_builder + } + + /// Returns the number of elements the map can hold without reallocating. + /// + /// This number is a lower bound; the `HashMap<K, V>` might be able to hold + /// more, but is guaranteed to be able to hold at least this many. + /// + /// # Examples + /// + /// ``` + /// use std::collections::HashMap; + /// let map: HashMap<isize, isize> = HashMap::with_capacity(100); + /// assert!(map.capacity() >= 100); + /// ``` + #[inline] + pub fn capacity(&self) -> usize { + self.resize_policy.capacity(self.raw_capacity()) + } + + /// Returns the hash map's raw capacity. + #[inline] + fn raw_capacity(&self) -> usize { + 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`]. + /// + /// [`usize`]: ../../std/primitive.usize.html + /// + /// # Examples + /// + /// ``` + /// use std::collections::HashMap; + /// let mut map: HashMap<&str, isize> = HashMap::new(); + /// map.reserve(10); + /// ``` + pub fn reserve(&mut self, additional: usize) { + self.try_reserve(additional).unwrap(); + } + + #[inline] + pub fn try_reserve(&mut self, additional: usize) -> Result<(), FailedAllocationError> { + let remaining = self.capacity() - self.len(); // this can't overflow + if remaining < additional { + let min_cap = self + .len() + .checked_add(additional) + .expect("reserve overflow"); + let raw_cap = self.resize_policy.raw_capacity(min_cap); + self.try_resize(raw_cap)?; + } else if self.table.tag() && remaining <= self.len() { + // Probe sequence is too long and table is half full, + // resize early to reduce probing length. + let new_capacity = self.table.capacity() * 2; + self.try_resize(new_capacity)?; + } + Ok(()) + } + + #[cold] + #[inline(never)] + fn try_resize(&mut self, new_raw_cap: usize) -> Result<(), FailedAllocationError> { + assert!(self.table.size() <= new_raw_cap); + assert!(new_raw_cap.is_power_of_two() || new_raw_cap == 0); + + let mut old_table = replace(&mut self.table, RawTable::new(new_raw_cap)?); + let old_size = old_table.size(); + + if old_table.size() == 0 { + return Ok(()); + } + + let mut bucket = Bucket::head_bucket(&mut old_table); + + // 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); + if b.table().size() == 0 { + break; + } + b.into_bucket() + }, + Empty(b) => b.into_bucket(), + }; + bucket.next(); + } + + assert_eq!(self.table.size(), old_size); + Ok(()) + } + + /// 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); + /// ``` + pub fn shrink_to_fit(&mut self) { + self.try_shrink_to_fit().unwrap(); + } + + pub fn try_shrink_to_fit(&mut self) -> Result<(), FailedAllocationError> { + let new_raw_cap = self.resize_policy.raw_capacity(self.len()); + if self.raw_capacity() != new_raw_cap { + let old_table = replace(&mut self.table, RawTable::new(new_raw_cap)?); + 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); + } + Ok(()) + } + + /// 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) -> Option<V> { + let entry = search_hashed(&mut self.table, hash, |key| *key == k).into_entry(k); + match entry { + Some(Occupied(mut elem)) => Some(elem.insert(v)), + Some(Vacant(elem)) => { + elem.insert(v); + None + }, + None => unreachable!(), + } + } + + /// An iterator visiting all keys in arbitrary order. + /// The 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); + /// } + /// ``` + pub fn keys(&self) -> Keys<K, V> { + Keys { inner: self.iter() } + } + + /// An iterator visiting all values in arbitrary order. + /// The 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); + /// } + /// ``` + pub fn values(&self) -> Values<K, V> { + Values { inner: self.iter() } + } + + /// An iterator visiting all values mutably in arbitrary order. + /// The iterator element type is `&'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); + /// + /// for val in map.values_mut() { + /// *val = *val + 10; + /// } + /// + /// for val in map.values() { + /// println!("{}", val); + /// } + /// ``` + pub fn values_mut(&mut self) -> ValuesMut<K, V> { + ValuesMut { + inner: self.iter_mut(), + } + } + + /// An iterator visiting all key-value pairs in arbitrary order. + /// The 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); + /// } + /// ``` + 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. + /// The 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 { + /// println!("key: {} val: {}", key, val); + /// } + /// ``` + 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); + /// ``` + pub fn entry(&mut self, key: K) -> Entry<K, V> { + self.try_entry(key).unwrap() + } + + #[inline(always)] + pub fn try_entry(&mut self, key: K) -> Result<Entry<K, V>, FailedAllocationError> { + // Gotta resize now. + self.try_reserve(1)?; + let hash = self.make_hash(&key); + Ok(search_hashed(&mut self.table, hash, |q| q.eq(&key)) + .into_entry(key) + .expect("unreachable")) + } + + /// 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); + /// ``` + 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] + 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 + /// + /// ``` + /// 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] + pub fn drain(&mut self) -> Drain<K, V> + where + K: 'static, + V: 'static, + { + Drain { + inner: self.table.drain(), + } + } + + /// 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()); + /// ``` + #[inline] + pub fn clear(&mut self) + where + K: 'static, + V: 'static, + { + 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. + /// + /// [`Eq`]: ../../std/cmp/trait.Eq.html + /// [`Hash`]: ../../std/hash/trait.Hash.html + /// + /// # 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); + /// ``` + pub fn get<Q: ?Sized>(&self, k: &Q) -> Option<&V> + where + K: Borrow<Q>, + Q: Hash + Eq, + { + self.search(k) + .into_occupied_bucket() + .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. + /// + /// [`Eq`]: ../../std/cmp/trait.Eq.html + /// [`Hash`]: ../../std/hash/trait.Hash.html + /// + /// # 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); + /// ``` + pub fn contains_key<Q: ?Sized>(&self, k: &Q) -> bool + where + K: Borrow<Q>, + Q: Hash + Eq, + { + self.search(k).into_occupied_bucket().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. + /// + /// [`Eq`]: ../../std/cmp/trait.Eq.html + /// [`Hash`]: ../../std/hash/trait.Hash.html + /// + /// # 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"); + /// ``` + pub fn get_mut<Q: ?Sized>(&mut self, k: &Q) -> Option<&mut V> + where + K: Borrow<Q>, + Q: Hash + Eq, + { + self.search_mut(k) + .into_occupied_bucket() + .map(|bucket| bucket.into_mut_refs().1) + } + + /// Inserts a key-value pair into the map. + /// + /// If the map did not have this key present, [`None`] is returned. + /// + /// If the map did have this key present, the value is updated, and the old + /// value is returned. The key is not updated, though; this matters for + /// types that can be `==` without being identical. See the [module-level + /// documentation] for more. + /// + /// [`None`]: ../../std/option/enum.Option.html#variant.None + /// [module-level documentation]: index.html#insert-and-complex-keys + /// + /// # 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"); + /// ``` + pub fn insert(&mut self, k: K, v: V) -> Option<V> { + self.try_insert(k, v).unwrap() + } + + #[inline] + pub fn try_insert(&mut self, k: K, v: V) -> Result<Option<V>, FailedAllocationError> { + let hash = self.make_hash(&k); + self.try_reserve(1)?; + Ok(self.insert_hashed_nocheck(hash, k, v)) + } + + /// 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. + /// + /// [`Eq`]: ../../std/cmp/trait.Eq.html + /// [`Hash`]: ../../std/hash/trait.Hash.html + /// + /// # 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); + /// ``` + 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) + .into_occupied_bucket() + .map(|bucket| pop_internal(bucket).1) + } + + /// Retains only the elements specified by the predicate. + /// + /// In other words, remove all pairs `(k, v)` such that `f(&k,&mut v)` returns `false`. + /// + /// # Examples + /// + /// ``` + /// use std::collections::HashMap; + /// + /// let mut map: HashMap<isize, isize> = (0..8).map(|x|(x, x*10)).collect(); + /// map.retain(|&k, _| k % 2 == 0); + /// assert_eq!(map.len(), 4); + /// ``` + pub fn retain<F>(&mut self, mut f: F) + where + F: FnMut(&K, &mut V) -> bool, + { + if self.table.size() == 0 { + return; + } + let mut elems_left = self.table.size(); + let mut bucket = Bucket::head_bucket(&mut self.table); + bucket.prev(); + let start_index = bucket.index(); + while elems_left != 0 { + bucket = match bucket.peek() { + Full(mut full) => { + elems_left -= 1; + let should_remove = { + let (k, v) = full.read_mut(); + !f(k, v) + }; + if should_remove { + let prev_raw = full.raw(); + let (_, _, t) = pop_internal(full); + Bucket::new_from(prev_raw, t) + } else { + full.into_bucket() + } + }, + Empty(b) => b.into_bucket(), + }; + bucket.prev(); // reverse iteration + debug_assert!(elems_left == 0 || bucket.index() != start_index); + } + } +} + +impl<K, V, S> PartialEq for HashMap<K, V, S> +where + K: Eq + Hash, + V: PartialEq, + S: BuildHasher, +{ + 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)) + } +} + +impl<K, V, S> Eq for HashMap<K, V, S> +where + K: Eq + Hash, + V: Eq, + S: BuildHasher, +{ +} + +impl<K, V, S> Debug for HashMap<K, V, S> +where + K: Eq + Hash + Debug, + V: Debug, + S: BuildHasher, +{ + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.debug_map().entries(self.iter()).finish() + } +} + +impl<K, V, S> Default for HashMap<K, V, S> +where + K: Eq + Hash, + S: BuildHasher + Default, +{ + /// Creates an empty `HashMap<K, V, S>`, with the `Default` value for the hasher. + fn default() -> HashMap<K, V, S> { + HashMap::with_hasher(Default::default()) + } +} + +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: BuildHasher, +{ + type Output = V; + + #[inline] + fn index(&self, index: &Q) -> &V { + self.get(index).expect("no entry found for key") + } +} + +/// An iterator over the entries of a `HashMap`. +/// +/// This `struct` is created by the [`iter`] method on [`HashMap`]. See its +/// documentation for more. +/// +/// [`iter`]: struct.HashMap.html#method.iter +/// [`HashMap`]: struct.HashMap.html +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(), + } + } +} + +impl<'a, K: Debug, V: Debug> fmt::Debug for Iter<'a, K, V> { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.debug_list().entries(self.clone()).finish() + } +} + +/// A mutable iterator over the entries of a `HashMap`. +/// +/// This `struct` is created by the [`iter_mut`] method on [`HashMap`]. See its +/// documentation for more. +/// +/// [`iter_mut`]: struct.HashMap.html#method.iter_mut +/// [`HashMap`]: struct.HashMap.html +pub struct IterMut<'a, K: 'a, V: 'a> { + inner: table::IterMut<'a, K, V>, +} + +/// An owning iterator over the entries of a `HashMap`. +/// +/// This `struct` is created by the [`into_iter`] method on [`HashMap`][`HashMap`] +/// (provided by the `IntoIterator` trait). See its documentation for more. +/// +/// [`into_iter`]: struct.HashMap.html#method.into_iter +/// [`HashMap`]: struct.HashMap.html +pub struct IntoIter<K, V> { + pub(super) inner: table::IntoIter<K, V>, +} + +/// An iterator over the keys of a `HashMap`. +/// +/// This `struct` is created by the [`keys`] method on [`HashMap`]. See its +/// documentation for more. +/// +/// [`keys`]: struct.HashMap.html#method.keys +/// [`HashMap`]: struct.HashMap.html +pub struct Keys<'a, K: 'a, V: 'a> { + inner: Iter<'a, K, V>, +} + +// 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(), + } + } +} + +impl<'a, K: Debug, V> fmt::Debug for Keys<'a, K, V> { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.debug_list().entries(self.clone()).finish() + } +} + +/// An iterator over the values of a `HashMap`. +/// +/// This `struct` is created by the [`values`] method on [`HashMap`]. See its +/// documentation for more. +/// +/// [`values`]: struct.HashMap.html#method.values +/// [`HashMap`]: struct.HashMap.html +pub struct Values<'a, K: 'a, V: 'a> { + inner: Iter<'a, K, 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(), + } + } +} + +impl<'a, K, V: Debug> fmt::Debug for Values<'a, K, V> { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.debug_list().entries(self.clone()).finish() + } +} + +/// A draining iterator over the entries of a `HashMap`. +/// +/// This `struct` is created by the [`drain`] method on [`HashMap`]. See its +/// documentation for more. +/// +/// [`drain`]: struct.HashMap.html#method.drain +/// [`HashMap`]: struct.HashMap.html +pub struct Drain<'a, K: 'static, V: 'static> { + pub(super) inner: table::Drain<'a, K, V>, +} + +/// A mutable iterator over the values of a `HashMap`. +/// +/// This `struct` is created by the [`values_mut`] method on [`HashMap`]. See its +/// documentation for more. +/// +/// [`values_mut`]: struct.HashMap.html#method.values_mut +/// [`HashMap`]: struct.HashMap.html +pub struct ValuesMut<'a, K: 'a, V: 'a> { + inner: IterMut<'a, K, V>, +} + +enum InternalEntry<K, V, M> { + Occupied { + elem: FullBucket<K, V, M>, + }, + Vacant { + hash: SafeHash, + elem: VacantEntryState<K, V, M>, + }, + TableIsEmpty, +} + +impl<K, V, M> InternalEntry<K, V, M> { + #[inline] + fn into_occupied_bucket(self) -> Option<FullBucket<K, V, M>> { + match self { + InternalEntry::Occupied { elem } => Some(elem), + _ => None, + } + } +} + +impl<'a, K, V> InternalEntry<K, V, &'a mut RawTable<K, V>> { + #[inline] + fn into_entry(self, key: K) -> Option<Entry<'a, K, V>> { + match self { + InternalEntry::Occupied { elem } => Some(Occupied(OccupiedEntry { + key: Some(key), + elem, + })), + InternalEntry::Vacant { hash, elem } => Some(Vacant(VacantEntry { hash, key, elem })), + InternalEntry::TableIsEmpty => None, + } + } +} + +/// A view into a single entry in a map, which may either be vacant or occupied. +/// +/// This `enum` is constructed from the [`entry`] method on [`HashMap`]. +/// +/// [`HashMap`]: struct.HashMap.html +/// [`entry`]: struct.HashMap.html#method.entry +pub enum Entry<'a, K: 'a, V: 'a> { + /// An occupied entry. + Occupied(OccupiedEntry<'a, K, V>), + + /// A vacant entry. + Vacant(VacantEntry<'a, K, V>), +} + +impl<'a, K: 'a + Debug, V: 'a + Debug> Debug for Entry<'a, K, V> { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + match *self { + Vacant(ref v) => f.debug_tuple("Entry").field(v).finish(), + Occupied(ref o) => f.debug_tuple("Entry").field(o).finish(), + } + } +} + +/// A view into an occupied entry in a `HashMap`. +/// It is part of the [`Entry`] enum. +/// +/// [`Entry`]: enum.Entry.html +pub struct OccupiedEntry<'a, K: 'a, V: 'a> { + key: Option<K>, + elem: FullBucket<K, V, &'a mut RawTable<K, V>>, +} + +impl<'a, K: 'a + Debug, V: 'a + Debug> Debug for OccupiedEntry<'a, K, V> { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.debug_struct("OccupiedEntry") + .field("key", self.key()) + .field("value", self.get()) + .finish() + } +} + +/// A view into a vacant entry in a `HashMap`. +/// It is part of the [`Entry`] enum. +/// +/// [`Entry`]: enum.Entry.html +pub struct VacantEntry<'a, K: 'a, V: 'a> { + hash: SafeHash, + key: K, + elem: VacantEntryState<K, V, &'a mut RawTable<K, V>>, +} + +impl<'a, K: 'a + Debug, V: 'a> Debug for VacantEntry<'a, K, V> { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.debug_tuple("VacantEntry").field(self.key()).finish() + } +} + +/// 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>, usize), +} + +impl<'a, K, V, S> IntoIterator for &'a HashMap<K, V, S> +where + K: Eq + Hash, + S: BuildHasher, +{ + type Item = (&'a K, &'a V); + type IntoIter = Iter<'a, K, V>; + + fn into_iter(self) -> Iter<'a, K, V> { + self.iter() + } +} + +impl<'a, K, V, S> IntoIterator for &'a mut HashMap<K, V, S> +where + K: Eq + Hash, + S: BuildHasher, +{ + type Item = (&'a K, &'a mut V); + type IntoIter = IterMut<'a, K, V>; + + fn into_iter(self) -> IterMut<'a, K, V> { + self.iter_mut() + } +} + +impl<K, V, S> IntoIterator for HashMap<K, V, S> +where + K: Eq + Hash, + S: BuildHasher, +{ + 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> { + IntoIter { + inner: self.table.into_iter(), + } + } +} + +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() + } +} +impl<'a, K, V> ExactSizeIterator for Iter<'a, K, V> { + #[inline] + fn len(&self) -> usize { + self.inner.len() + } +} + +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() + } +} +impl<'a, K, V> ExactSizeIterator for IterMut<'a, K, V> { + #[inline] + fn len(&self) -> usize { + self.inner.len() + } +} + +impl<'a, K, V> fmt::Debug for IterMut<'a, K, V> +where + K: fmt::Debug, + V: fmt::Debug, +{ + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.debug_list().entries(self.inner.iter()).finish() + } +} + +impl<K, V> Iterator for IntoIter<K, V> { + type Item = (K, V); + + #[inline] + fn next(&mut self) -> Option<(K, V)> { + self.inner.next().map(|(_, k, v)| (k, v)) + } + #[inline] + fn size_hint(&self) -> (usize, Option<usize>) { + self.inner.size_hint() + } +} +impl<K, V> ExactSizeIterator for IntoIter<K, V> { + #[inline] + fn len(&self) -> usize { + self.inner.len() + } +} + +impl<K: Debug, V: Debug> fmt::Debug for IntoIter<K, V> { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.debug_list().entries(self.inner.iter()).finish() + } +} + +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().map(|(k, _)| k) + } + #[inline] + fn size_hint(&self) -> (usize, Option<usize>) { + self.inner.size_hint() + } +} +impl<'a, K, V> ExactSizeIterator for Keys<'a, K, V> { + #[inline] + fn len(&self) -> usize { + self.inner.len() + } +} + +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().map(|(_, v)| v) + } + #[inline] + fn size_hint(&self) -> (usize, Option<usize>) { + self.inner.size_hint() + } +} +impl<'a, K, V> ExactSizeIterator for Values<'a, K, V> { + #[inline] + fn len(&self) -> usize { + self.inner.len() + } +} +impl<'a, K, V> Iterator for ValuesMut<'a, K, V> { + type Item = &'a mut V; + + #[inline] + fn next(&mut self) -> Option<&'a mut V> { + self.inner.next().map(|(_, v)| v) + } + #[inline] + fn size_hint(&self) -> (usize, Option<usize>) { + self.inner.size_hint() + } +} +impl<'a, K, V> ExactSizeIterator for ValuesMut<'a, K, V> { + #[inline] + fn len(&self) -> usize { + self.inner.len() + } +} + +impl<'a, K, V> fmt::Debug for ValuesMut<'a, K, V> +where + K: fmt::Debug, + V: fmt::Debug, +{ + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.debug_list().entries(self.inner.inner.iter()).finish() + } +} + +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().map(|(_, k, v)| (k, v)) + } + #[inline] + fn size_hint(&self) -> (usize, Option<usize>) { + self.inner.size_hint() + } +} +impl<'a, K, V> ExactSizeIterator for Drain<'a, K, V> { + #[inline] + fn len(&self) -> usize { + self.inner.len() + } +} + +impl<'a, K, V> fmt::Debug for Drain<'a, K, V> +where + K: fmt::Debug, + V: fmt::Debug, +{ + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.debug_list().entries(self.inner.iter()).finish() + } +} + +// FORK NOTE: Removed Placer impl + +impl<'a, K, V> Entry<'a, K, V> { + /// Ensures a value is in the entry by inserting the default if empty, and returns + /// a mutable reference to the value in the entry. + /// + /// # Examples + /// + /// ``` + /// use std::collections::HashMap; + /// + /// let mut map: HashMap<&str, u32> = HashMap::new(); + /// map.entry("poneyland").or_insert(12); + /// + /// assert_eq!(map["poneyland"], 12); + /// + /// *map.entry("poneyland").or_insert(12) += 10; + /// assert_eq!(map["poneyland"], 22); + /// ``` + pub fn or_insert(self, default: V) -> &'a mut V { + match self { + Occupied(entry) => entry.into_mut(), + Vacant(entry) => entry.insert(default), + } + } + + /// 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. + /// + /// # Examples + /// + /// ``` + /// use std::collections::HashMap; + /// + /// let mut map: HashMap<&str, String> = HashMap::new(); + /// let s = "hoho".to_string(); + /// + /// map.entry("poneyland").or_insert_with(|| s); + /// + /// assert_eq!(map["poneyland"], "hoho".to_string()); + /// ``` + 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()), + } + } + + /// Returns a reference to this entry's key. + /// + /// # Examples + /// + /// ``` + /// use std::collections::HashMap; + /// + /// let mut map: HashMap<&str, u32> = HashMap::new(); + /// assert_eq!(map.entry("poneyland").key(), &"poneyland"); + /// ``` + pub fn key(&self) -> &K { + match *self { + Occupied(ref entry) => entry.key(), + Vacant(ref entry) => entry.key(), + } + } +} + +impl<'a, K, V> OccupiedEntry<'a, K, V> { + /// Gets a reference to the key in the entry. + /// + /// # Examples + /// + /// ``` + /// use std::collections::HashMap; + /// + /// let mut map: HashMap<&str, u32> = HashMap::new(); + /// map.entry("poneyland").or_insert(12); + /// assert_eq!(map.entry("poneyland").key(), &"poneyland"); + /// ``` + pub fn key(&self) -> &K { + self.elem.read().0 + } + + /// Take the ownership of the key and value from the map. + /// + /// # Examples + /// + /// ``` + /// use std::collections::HashMap; + /// use std::collections::hash_map::Entry; + /// + /// let mut map: HashMap<&str, u32> = HashMap::new(); + /// map.entry("poneyland").or_insert(12); + /// + /// if let Entry::Occupied(o) = map.entry("poneyland") { + /// // We delete the entry from the map. + /// o.remove_entry(); + /// } + /// + /// assert_eq!(map.contains_key("poneyland"), false); + /// ``` + pub fn remove_entry(self) -> (K, V) { + let (k, v, _) = pop_internal(self.elem); + (k, v) + } + + /// Gets a reference to the value in the entry. + /// + /// # Examples + /// + /// ``` + /// use std::collections::HashMap; + /// use std::collections::hash_map::Entry; + /// + /// let mut map: HashMap<&str, u32> = HashMap::new(); + /// map.entry("poneyland").or_insert(12); + /// + /// if let Entry::Occupied(o) = map.entry("poneyland") { + /// assert_eq!(o.get(), &12); + /// } + /// ``` + pub fn get(&self) -> &V { + self.elem.read().1 + } + + /// Gets a mutable reference to the value in the entry. + /// + /// # Examples + /// + /// ``` + /// use std::collections::HashMap; + /// use std::collections::hash_map::Entry; + /// + /// let mut map: HashMap<&str, u32> = HashMap::new(); + /// map.entry("poneyland").or_insert(12); + /// + /// assert_eq!(map["poneyland"], 12); + /// if let Entry::Occupied(mut o) = map.entry("poneyland") { + /// *o.get_mut() += 10; + /// } + /// + /// assert_eq!(map["poneyland"], 22); + /// ``` + 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. + /// + /// # Examples + /// + /// ``` + /// use std::collections::HashMap; + /// use std::collections::hash_map::Entry; + /// + /// let mut map: HashMap<&str, u32> = HashMap::new(); + /// map.entry("poneyland").or_insert(12); + /// + /// assert_eq!(map["poneyland"], 12); + /// if let Entry::Occupied(o) = map.entry("poneyland") { + /// *o.into_mut() += 10; + /// } + /// + /// assert_eq!(map["poneyland"], 22); + /// ``` + 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. + /// + /// # Examples + /// + /// ``` + /// use std::collections::HashMap; + /// use std::collections::hash_map::Entry; + /// + /// let mut map: HashMap<&str, u32> = HashMap::new(); + /// map.entry("poneyland").or_insert(12); + /// + /// if let Entry::Occupied(mut o) = map.entry("poneyland") { + /// assert_eq!(o.insert(15), 12); + /// } + /// + /// assert_eq!(map["poneyland"], 15); + /// ``` + 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. + /// + /// # Examples + /// + /// ``` + /// use std::collections::HashMap; + /// use std::collections::hash_map::Entry; + /// + /// let mut map: HashMap<&str, u32> = HashMap::new(); + /// map.entry("poneyland").or_insert(12); + /// + /// if let Entry::Occupied(o) = map.entry("poneyland") { + /// assert_eq!(o.remove(), 12); + /// } + /// + /// assert_eq!(map.contains_key("poneyland"), false); + /// ``` + pub fn remove(self) -> V { + pop_internal(self.elem).1 + } + + /// Returns a key that was used for search. + /// + /// The key was retained for further use. + fn take_key(&mut self) -> Option<K> { + self.key.take() + } +} + +impl<'a, K: 'a, V: 'a> VacantEntry<'a, K, V> { + /// Gets a reference to the key that would be used when inserting a value + /// through the `VacantEntry`. + /// + /// # Examples + /// + /// ``` + /// use std::collections::HashMap; + /// + /// let mut map: HashMap<&str, u32> = HashMap::new(); + /// assert_eq!(map.entry("poneyland").key(), &"poneyland"); + /// ``` + pub fn key(&self) -> &K { + &self.key + } + + /// Take ownership of the key. + /// + /// # Examples + /// + /// ``` + /// use std::collections::HashMap; + /// use std::collections::hash_map::Entry; + /// + /// let mut map: HashMap<&str, u32> = HashMap::new(); + /// + /// if let Entry::Vacant(v) = map.entry("poneyland") { + /// v.into_key(); + /// } + /// ``` + pub fn into_key(self) -> K { + self.key + } + + /// Sets the value of the entry with the VacantEntry's key, + /// and returns a mutable reference to it. + /// + /// # Examples + /// + /// ``` + /// use std::collections::HashMap; + /// use std::collections::hash_map::Entry; + /// + /// let mut map: HashMap<&str, u32> = HashMap::new(); + /// + /// if let Entry::Vacant(o) = map.entry("poneyland") { + /// o.insert(37); + /// } + /// assert_eq!(map["poneyland"], 37); + /// ``` + pub fn insert(self, value: V) -> &'a mut V { + let b = match self.elem { + NeqElem(mut bucket, disp) => { + if disp >= DISPLACEMENT_THRESHOLD { + bucket.table_mut().set_tag(true); + } + robin_hood(bucket, disp, self.hash, self.key, value) + }, + NoElem(mut bucket, disp) => { + if disp >= DISPLACEMENT_THRESHOLD { + bucket.table_mut().set_tag(true); + } + bucket.put(self.hash, self.key, value) + }, + }; + b.into_mut_refs().1 + } +} + +impl<K, V, S> FromIterator<(K, V)> for HashMap<K, V, S> +where + K: Eq + Hash, + S: BuildHasher + Default, +{ + fn from_iter<T: IntoIterator<Item = (K, V)>>(iter: T) -> HashMap<K, V, S> { + let mut map = HashMap::with_hasher(Default::default()); + map.extend(iter); + map + } +} + +impl<K, V, S> Extend<(K, V)> for HashMap<K, V, S> +where + K: Eq + Hash, + S: BuildHasher, +{ + fn extend<T: IntoIterator<Item = (K, V)>>(&mut self, iter: T) { + // Keys may be already present or show multiple times in the iterator. + // Reserve the entire hint lower bound if the map is empty. + // Otherwise reserve half the hint (rounded up), so the map + // will only resize twice in the worst case. + let iter = iter.into_iter(); + let reserve = if self.is_empty() { + iter.size_hint().0 + } else { + (iter.size_hint().0 + 1) / 2 + }; + self.reserve(reserve); + for (k, v) in iter { + self.insert(k, v); + } + } +} + +impl<'a, K, V, S> Extend<(&'a K, &'a V)> for HashMap<K, V, S> +where + K: Eq + Hash + Copy, + V: Copy, + S: BuildHasher, +{ + fn extend<T: IntoIterator<Item = (&'a K, &'a V)>>(&mut self, iter: T) { + self.extend(iter.into_iter().map(|(&key, &value)| (key, value))); + } +} + +// FORK NOTE: These can be reused +pub use std::collections::hash_map::{DefaultHasher, RandomState}; + +impl<K, S, Q: ?Sized> super::Recover<Q> for HashMap<K, (), S> +where + K: Eq + Hash + Borrow<Q>, + S: BuildHasher, + Q: Eq + Hash, +{ + type Key = K; + + fn get(&self, key: &Q) -> Option<&K> { + self.search(key) + .into_occupied_bucket() + .map(|bucket| bucket.into_refs().0) + } + + fn take(&mut self, key: &Q) -> Option<K> { + if self.table.size() == 0 { + return None; + } + + self.search_mut(key) + .into_occupied_bucket() + .map(|bucket| pop_internal(bucket).0) + } + + fn replace(&mut self, key: K) -> Option<K> { + self.reserve(1); + + match self.entry(key) { + Occupied(mut occupied) => { + let key = occupied.take_key().unwrap(); + Some(mem::replace(occupied.elem.read_mut().0, key)) + }, + Vacant(vacant) => { + vacant.insert(()); + None + }, + } + } +} + +#[allow(dead_code)] +fn assert_covariance() { + fn map_key<'new>(v: HashMap<&'static str, u8>) -> HashMap<&'new str, u8> { + v + } + fn map_val<'new>(v: HashMap<u8, &'static str>) -> HashMap<u8, &'new str> { + v + } + fn iter_key<'a, 'new>(v: Iter<'a, &'static str, u8>) -> Iter<'a, &'new str, u8> { + v + } + fn iter_val<'a, 'new>(v: Iter<'a, u8, &'static str>) -> Iter<'a, u8, &'new str> { + v + } + fn into_iter_key<'new>(v: IntoIter<&'static str, u8>) -> IntoIter<&'new str, u8> { + v + } + fn into_iter_val<'new>(v: IntoIter<u8, &'static str>) -> IntoIter<u8, &'new str> { + v + } + fn keys_key<'a, 'new>(v: Keys<'a, &'static str, u8>) -> Keys<'a, &'new str, u8> { + v + } + fn keys_val<'a, 'new>(v: Keys<'a, u8, &'static str>) -> Keys<'a, u8, &'new str> { + v + } + fn values_key<'a, 'new>(v: Values<'a, &'static str, u8>) -> Values<'a, &'new str, u8> { + v + } + fn values_val<'a, 'new>(v: Values<'a, u8, &'static str>) -> Values<'a, u8, &'new str> { + v + } + fn drain<'new>( + d: Drain<'static, &'static str, &'static str>, + ) -> Drain<'new, &'new str, &'new str> { + d + } +} + +#[cfg(test)] +mod test_map { + extern crate rand; + use self::rand::{thread_rng, Rng}; + use super::Entry::{Occupied, Vacant}; + use super::HashMap; + use super::RandomState; + use cell::RefCell; + + #[test] + fn test_zero_capacities() { + type HM = HashMap<i32, i32>; + + let m = HM::new(); + assert_eq!(m.capacity(), 0); + + let m = HM::default(); + assert_eq!(m.capacity(), 0); + + let m = HM::with_hasher(RandomState::new()); + assert_eq!(m.capacity(), 0); + + let m = HM::with_capacity(0); + assert_eq!(m.capacity(), 0); + + let m = HM::with_capacity_and_hasher(0, RandomState::new()); + assert_eq!(m.capacity(), 0); + + let mut m = HM::new(); + m.insert(1, 1); + m.insert(2, 2); + m.remove(&1); + m.remove(&2); + m.shrink_to_fit(); + assert_eq!(m.capacity(), 0); + + let mut m = HM::new(); + m.reserve(0); + assert_eq!(m.capacity(), 0); + } + + #[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); + } + + #[test] + fn test_clone() { + 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); + let m2 = m.clone(); + assert_eq!(*m2.get(&1).unwrap(), 2); + assert_eq!(*m2.get(&2).unwrap(), 4); + assert_eq!(m2.len(), 2); + } + + 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() = vec![0; 200]; + }); + + { + 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_into_iter_drops() { + DROP_VECTOR.with(|v| { + *v.borrow_mut() = vec![0; 200]; + }); + + 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_remove() { + let mut m: HashMap<isize, bool> = HashMap::new(); + assert_eq!(m.remove(&0), None); + } + + #[test] + fn test_empty_entry() { + let mut m: HashMap<isize, bool> = HashMap::new(); + match m.entry(0) { + Occupied(_) => panic!(), + Vacant(_) => {}, + } + assert!(*m.entry(0).or_insert(true)); + assert_eq!(m.len(), 1); + } + + #[test] + fn test_empty_iter() { + let mut m: HashMap<isize, bool> = HashMap::new(); + assert_eq!(m.drain().next(), None); + assert_eq!(m.keys().next(), None); + assert_eq!(m.values().next(), None); + assert_eq!(m.values_mut().next(), None); + assert_eq!(m.iter().next(), None); + assert_eq!(m.iter_mut().next(), None); + assert_eq!(m.len(), 0); + assert!(m.is_empty()); + assert_eq!(m.into_iter().next(), 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 1..1001 { + assert!(m.insert(i, i).is_none()); + + for j in 1..i + 1 { + let r = m.get(&j); + assert_eq!(r, Some(&j)); + } + + for j in i + 1..1001 { + let r = m.get(&j); + assert_eq!(r, None); + } + } + + for i in 1001..2001 { + assert!(!m.contains_key(&i)); + } + + // remove forwards + for i in 1..1001 { + assert!(m.remove(&i).is_some()); + + for j in 1..i + 1 { + assert!(!m.contains_key(&j)); + } + + for j in i + 1..1001 { + assert!(m.contains_key(&j)); + } + } + + for i in 1..1001 { + assert!(!m.contains_key(&i)); + } + + for i in 1..1001 { + assert!(m.insert(i, i).is_none()); + } + + // remove backwards + for i in (1..1001).rev() { + assert!(m.remove(&i).is_some()); + + for j in i..1001 { + assert!(!m.contains_key(&j)); + } + + for j in 1..i { + 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_values_mut() { + let vec = vec![(1, 1), (2, 2), (3, 3)]; + let mut map: HashMap<_, _> = vec.into_iter().collect(); + for value in map.values_mut() { + *value = (*value) * 2 + } + let values: Vec<_> = map.values().cloned().collect(); + assert_eq!(values.len(), 3); + assert!(values.contains(&2)); + assert!(values.contains(&4)); + assert!(values.contains(&6)); + } + + #[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_ne!(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_raw_cap = m.raw_capacity(); + while old_raw_cap == m.raw_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.raw_capacity(), 0); + assert!(m.is_empty()); + + m.insert(0, 0); + m.remove(&0); + assert!(m.is_empty()); + let initial_raw_cap = m.raw_capacity(); + m.reserve(initial_raw_cap); + let raw_cap = m.raw_capacity(); + + assert_eq!(raw_cap, initial_raw_cap * 2); + + let mut i = 0; + for _ in 0..raw_cap * 3 / 4 { + m.insert(i, i); + i += 1; + } + // three quarters full + + assert_eq!(m.len(), i); + assert_eq!(m.raw_capacity(), raw_cap); + + for _ in 0..raw_cap / 4 { + m.insert(i, i); + i += 1; + } + // half full + + let new_raw_cap = m.raw_capacity(); + assert_eq!(new_raw_cap, raw_cap * 2); + + for _ in 0..raw_cap / 2 - 1 { + i -= 1; + m.remove(&i); + assert_eq!(m.raw_capacity(), new_raw_cap); + } + // A little more than one quarter full. + m.shrink_to_fit(); + assert_eq!(m.raw_capacity(), raw_cap); + // again, a little more than half full + for _ in 0..raw_cap / 2 - 1 { + i -= 1; + m.remove(&i); + } + m.shrink_to_fit(); + + assert_eq!(m.len(), i); + assert!(!m.is_empty()); + assert_eq!(m.raw_capacity(), initial_raw_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); + } + } + + #[test] + fn test_extend_ref() { + let mut a = HashMap::new(); + a.insert(1, "one"); + let mut b = HashMap::new(); + b.insert(2, "two"); + b.insert(3, "three"); + + a.extend(&b); + + assert_eq!(a.len(), 3); + assert_eq!(a[&1], "one"); + assert_eq!(a[&2], "two"); + assert_eq!(a[&3], "three"); + } + + #[test] + fn test_capacity_not_less_than_len() { + let mut a = HashMap::new(); + let mut item = 0; + + for _ in 0..116 { + a.insert(item, 0); + item += 1; + } + + assert!(a.capacity() > a.len()); + + let free = a.capacity() - a.len(); + for _ in 0..free { + a.insert(item, 0); + item += 1; + } + + assert_eq!(a.len(), a.capacity()); + + // Insert at capacity should cause allocation. + a.insert(item, 0); + assert!(a.capacity() > a.len()); + } + + #[test] + fn test_occupied_entry_key() { + let mut a = HashMap::new(); + let key = "hello there"; + let value = "value goes here"; + assert!(a.is_empty()); + a.insert(key.clone(), value.clone()); + assert_eq!(a.len(), 1); + assert_eq!(a[key], value); + + match a.entry(key.clone()) { + Vacant(_) => panic!(), + Occupied(e) => assert_eq!(key, *e.key()), + } + assert_eq!(a.len(), 1); + assert_eq!(a[key], value); + } + + #[test] + fn test_vacant_entry_key() { + let mut a = HashMap::new(); + let key = "hello there"; + let value = "value goes here"; + + assert!(a.is_empty()); + match a.entry(key.clone()) { + Occupied(_) => panic!(), + Vacant(e) => { + assert_eq!(key, *e.key()); + e.insert(value.clone()); + }, + } + assert_eq!(a.len(), 1); + assert_eq!(a[key], value); + } + + #[test] + fn test_retain() { + let mut map: HashMap<isize, isize> = (0..100).map(|x| (x, x * 10)).collect(); + + map.retain(|&k, _| k % 2 == 0); + assert_eq!(map.len(), 50); + assert_eq!(map[&2], 20); + assert_eq!(map[&4], 40); + assert_eq!(map[&6], 60); + } + + #[test] + fn test_adaptive() { + const TEST_LEN: usize = 5000; + // by cloning we get maps with the same hasher seed + let mut first = HashMap::new(); + let mut second = first.clone(); + first.extend((0..TEST_LEN).map(|i| (i, i))); + second.extend((TEST_LEN..TEST_LEN * 2).map(|i| (i, i))); + + for (&k, &v) in &second { + let prev_cap = first.capacity(); + let expect_grow = first.len() == prev_cap; + first.insert(k, v); + if !expect_grow && first.capacity() != prev_cap { + return; + } + } + panic!("Adaptive early resize failed"); + } +} |