diff options
Diffstat (limited to 'src/libstd/collections/hash')
| -rw-r--r-- | src/libstd/collections/hash/bench.rs | 130 | ||||
| -rw-r--r-- | src/libstd/collections/hash/map.rs | 2133 | ||||
| -rw-r--r-- | src/libstd/collections/hash/mod.rs | 16 | ||||
| -rw-r--r-- | src/libstd/collections/hash/set.rs | 834 | ||||
| -rw-r--r-- | src/libstd/collections/hash/table.rs | 907 |
5 files changed, 4020 insertions, 0 deletions
diff --git a/src/libstd/collections/hash/bench.rs b/src/libstd/collections/hash/bench.rs new file mode 100644 index 00000000000..62b93336a34 --- /dev/null +++ b/src/libstd/collections/hash/bench.rs @@ -0,0 +1,130 @@ +// Copyright 2014 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or +// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license +// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +#![cfg(test)] + +extern crate test; +use prelude::*; + +use self::test::Bencher; +use iter::{range_inclusive}; + +#[bench] +fn new_drop(b : &mut Bencher) { + use super::map::HashMap; + + b.iter(|| { + let m : HashMap<int, int> = HashMap::new(); + assert_eq!(m.len(), 0); + }) +} + +#[bench] +fn new_insert_drop(b : &mut Bencher) { + use super::map::HashMap; + + b.iter(|| { + let mut m = HashMap::new(); + m.insert(0i, 0i); + assert_eq!(m.len(), 1); + }) +} + +#[bench] +fn grow_by_insertion(b: &mut Bencher) { + use super::map::HashMap; + + let mut m = HashMap::new(); + + for i in range_inclusive(1i, 1000) { + m.insert(i, i); + } + + let mut k = 1001; + + b.iter(|| { + m.insert(k, k); + k += 1; + }); +} + +#[bench] +fn find_existing(b: &mut Bencher) { + use super::map::HashMap; + + let mut m = HashMap::new(); + + for i in range_inclusive(1i, 1000) { + m.insert(i, i); + } + + b.iter(|| { + for i in range_inclusive(1i, 1000) { + m.contains_key(&i); + } + }); +} + +#[bench] +fn find_nonexisting(b: &mut Bencher) { + use super::map::HashMap; + + let mut m = HashMap::new(); + + for i in range_inclusive(1i, 1000) { + m.insert(i, i); + } + + b.iter(|| { + for i in range_inclusive(1001i, 2000) { + m.contains_key(&i); + } + }); +} + +#[bench] +fn hashmap_as_queue(b: &mut Bencher) { + use super::map::HashMap; + + let mut m = HashMap::new(); + + for i in range_inclusive(1i, 1000) { + m.insert(i, i); + } + + let mut k = 1i; + + b.iter(|| { + m.pop(&k); + m.insert(k + 1000, k + 1000); + k += 1; + }); +} + +#[bench] +fn find_pop_insert(b: &mut Bencher) { + use super::map::HashMap; + + let mut m = HashMap::new(); + + for i in range_inclusive(1i, 1000) { + m.insert(i, i); + } + + let mut k = 1i; + + b.iter(|| { + m.find(&(k + 400)); + m.find(&(k + 2000)); + m.pop(&k); + m.insert(k + 1000, k + 1000); + k += 1; + }) +} diff --git a/src/libstd/collections/hash/map.rs b/src/libstd/collections/hash/map.rs new file mode 100644 index 00000000000..596e483c2f6 --- /dev/null +++ b/src/libstd/collections/hash/map.rs @@ -0,0 +1,2133 @@ +// Copyright 2014 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or +// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license +// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. +// +// ignore-lexer-test FIXME #15883 + +use clone::Clone; +use cmp::{max, Eq, Equiv, PartialEq}; +use default::Default; +use fmt::{mod, Show}; +use hash::{Hash, Hasher, RandomSipHasher}; +use iter::{mod, Iterator, FromIterator, Extendable}; +use kinds::Sized; +use mem::{mod, replace}; +use num; +use ops::{Deref, Index, IndexMut}; +use option::{Some, None, Option}; +use result::{Result, Ok, Err}; + +use super::table; +use super::table::{ + Bucket, + Empty, + EmptyBucket, + Full, + FullBucket, + FullBucketImm, + FullBucketMut, + RawTable, + SafeHash +}; + +const INITIAL_LOG2_CAP: uint = 5; +pub const INITIAL_CAPACITY: uint = 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 conditions: +/// +/// - if size > 0.909 * capacity: grow +/// - if size < 0.25 * capacity: shrink (if this won't bring capacity lower +/// than the minimum) +#[deriving(Clone)] +struct DefaultResizePolicy { + /// Doubled minimal capacity. The capacity must never drop below + /// the minimum capacity. (The check happens before the capacity + /// is potentially halved.) + minimum_capacity2: uint +} + +impl DefaultResizePolicy { + fn new(new_capacity: uint) -> DefaultResizePolicy { + DefaultResizePolicy { + minimum_capacity2: new_capacity << 1 + } + } + + #[inline] + fn capacity_range(&self, new_size: uint) -> (uint, uint) { + // Here, we are rephrasing the logic by specifying the ranges: + // + // - if `size * 1.1 < cap < size * 4`: don't resize + // - if `cap < minimum_capacity * 2`: don't shrink + // - otherwise, resize accordingly + ((new_size * 11) / 10, max(new_size << 2, self.minimum_capacity2)) + } + + #[inline] + fn reserve(&mut self, new_capacity: uint) { + self.minimum_capacity2 = new_capacity << 1; + } +} + +// 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_generic` 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. Intutively, +// 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 doc.rs + +/// A hash map implementation which uses linear probing with Robin +/// Hood bucket stealing. +/// +/// The hashes are all keyed by the task-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 `#[deriving(Eq, Hash)]`. +/// +/// 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/) +/// +/// # Example +/// +/// ``` +/// 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.iter() { +/// match book_reviews.find(book) { +/// Some(review) => println!("{}: {}", *book, *review), +/// None => println!("{} is unreviewed.", *book) +/// } +/// } +/// +/// // iterate over everything. +/// for (book, review) in book_reviews.iter() { +/// println!("{}: \"{}\"", *book, *review); +/// } +/// ``` +/// +/// The easiest way to use `HashMap` with a custom type is to derive `Eq` and `Hash`. +/// We must also derive `PartialEq`. +/// +/// ``` +/// use std::collections::HashMap; +/// +/// #[deriving(Hash, Eq, PartialEq, Show)] +/// struct Viking<'a> { +/// name: &'a str, +/// power: uint, +/// } +/// +/// let mut vikings = HashMap::new(); +/// +/// vikings.insert("Norway", Viking { name: "Einar", power: 9u }); +/// vikings.insert("Denmark", Viking { name: "Olaf", power: 4u }); +/// vikings.insert("Iceland", Viking { name: "Harald", power: 8u }); +/// +/// // Use derived implementation to print the vikings. +/// for (land, viking) in vikings.iter() { +/// println!("{} at {}", viking, land); +/// } +/// ``` +#[deriving(Clone)] +pub struct HashMap<K, V, H = RandomSipHasher> { + // All hashes are keyed on these values, to prevent hash collision attacks. + hasher: H, + + table: RawTable<K, V>, + + // We keep this at the end since it might as well have tail padding. + resize_policy: DefaultResizePolicy, +} + +/// Search for a pre-hashed key. +fn search_hashed_generic<K, V, M: Deref<RawTable<K, V>>>(table: M, + hash: &SafeHash, + is_match: |&K| -> bool) + -> SearchResult<K, V, M> { + 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() { + let matched = { + let (k, _) = full.read(); + is_match(k) + }; + + // If the key doesn't match, it can't be this one.. + if matched { + return FoundExisting(full); + } + } + + probe = full.next(); + } + + TableRef(probe.into_table()) +} + +fn search_hashed<K: Eq, V, M: Deref<RawTable<K, V>>>(table: M, hash: &SafeHash, k: &K) + -> SearchResult<K, V, M> { + search_hashed_generic(table, hash, |k_| *k == *k_) +} + +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. + return (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: uint, + 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() { + table::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! + let (_, v) = Bucket::at_index(b.into_table(), starting_index).peek() + .expect_full() + .into_mut_refs(); + return v; + }, + table::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: Eq + Hash<S>, V, S, H: Hasher<S>> HashMap<K, V, H> { + fn make_hash<Sized? X: Hash<S>>(&self, x: &X) -> SafeHash { + table::make_hash(&self.hasher, x) + } + + fn search_equiv<'a, Sized? Q: Hash<S> + Equiv<K>>(&'a self, q: &Q) + -> Option<FullBucketImm<'a, K, V>> { + let hash = self.make_hash(q); + search_hashed_generic(&self.table, &hash, |k| q.equiv(k)).into_option() + } + + fn search_equiv_mut<'a, Sized? Q: Hash<S> + Equiv<K>>(&'a mut self, q: &Q) + -> Option<FullBucketMut<'a, K, V>> { + let hash = self.make_hash(q); + search_hashed_generic(&mut self.table, &hash, |k| q.equiv(k)).into_option() + } + + /// 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>(&'a self, k: &K) -> Option<FullBucketImm<'a, K, V>> { + let hash = self.make_hash(k); + search_hashed(&self.table, &hash, k).into_option() + } + + fn search_mut<'a>(&'a mut self, k: &K) -> Option<FullBucketMut<'a, K, V>> { + let hash = self.make_hash(k); + search_hashed(&mut self.table, &hash, k).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, RandomSipHasher> { + /// Create an empty HashMap. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashMap; + /// let mut map: HashMap<&str, int> = HashMap::with_capacity(10); + /// ``` + #[inline] + pub fn new() -> HashMap<K, V, RandomSipHasher> { + let hasher = RandomSipHasher::new(); + HashMap::with_hasher(hasher) + } + + /// Creates an empty hash map with the given initial capacity. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashMap; + /// let mut map: HashMap<&str, int> = HashMap::with_capacity(10); + /// ``` + #[inline] + pub fn with_capacity(capacity: uint) -> HashMap<K, V, RandomSipHasher> { + let hasher = RandomSipHasher::new(); + HashMap::with_capacity_and_hasher(capacity, hasher) + } +} + +impl<K: Eq + Hash<S>, V, S, H: Hasher<S>> HashMap<K, V, H> { + /// Creates an empty hashmap which will use the given hasher to hash keys. + /// + /// The creates map has the default initial capacity. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashMap; + /// use std::hash::sip::SipHasher; + /// + /// let h = SipHasher::new(); + /// let mut map = HashMap::with_hasher(h); + /// map.insert(1i, 2u); + /// ``` + #[inline] + pub fn with_hasher(hasher: H) -> HashMap<K, V, H> { + HashMap { + hasher: hasher, + resize_policy: DefaultResizePolicy::new(INITIAL_CAPACITY), + table: RawTable::new(0), + } + } + + /// Create 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. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashMap; + /// use std::hash::sip::SipHasher; + /// + /// let h = SipHasher::new(); + /// let mut map = HashMap::with_capacity_and_hasher(10, h); + /// map.insert(1i, 2u); + /// ``` + #[inline] + pub fn with_capacity_and_hasher(capacity: uint, hasher: H) -> HashMap<K, V, H> { + let cap = num::next_power_of_two(max(INITIAL_CAPACITY, capacity)); + HashMap { + hasher: hasher, + resize_policy: DefaultResizePolicy::new(cap), + table: RawTable::new(cap), + } + } + + /// The hashtable will never try to shrink below this size. You can use + /// this function to reduce reallocations if your hashtable frequently + /// grows and shrinks by large amounts. + /// + /// This function has no effect on the operational semantics of the + /// hashtable, only on performance. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashMap; + /// let mut map: HashMap<&str, int> = HashMap::new(); + /// map.reserve(10); + /// ``` + pub fn reserve(&mut self, new_minimum_capacity: uint) { + let cap = num::next_power_of_two( + max(INITIAL_CAPACITY, new_minimum_capacity)); + + self.resize_policy.reserve(cap); + + if self.table.capacity() < cap { + self.resize(cap); + } + } + + /// 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. + fn resize(&mut self, new_capacity: uint) { + assert!(self.table.size() <= new_capacity); + assert!(num::is_power_of_two(new_capacity)); + + 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; + } + + if new_capacity < old_table.capacity() { + // Shrink the table. Naive algorithm for resizing: + for (h, k, v) in old_table.into_iter() { + self.insert_hashed_nocheck(h, k, v); + } + } else { + // 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); + } + + /// Performs any necessary resize operations, such that there's space for + /// new_size elements. + fn make_some_room(&mut self, new_size: uint) { + let (grow_at, shrink_at) = self.resize_policy.capacity_range(new_size); + let cap = self.table.capacity(); + + // An invalid value shouldn't make us run out of space. + debug_assert!(grow_at >= new_size); + + if cap <= grow_at { + let new_capacity = max(cap << 1, INITIAL_CAPACITY); + self.resize(new_capacity); + } else if shrink_at <= cap { + let new_capacity = cap >> 1; + self.resize(new_capacity); + } + } + + /// 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>(&'a mut self, + hash: SafeHash, + k: K, + v: V, + found_existing: |&mut K, &mut V, V|) + -> &'a mut 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! + let bucket = bucket.put(hash, k, v); + let (_, val) = bucket.into_mut_refs(); + return val; + }, + Full(bucket) => bucket + }; + + if bucket.hash() == hash { + let found_match = { + let (bucket_k, _) = bucket.read_mut(); + k == *bucket_k + }; + if found_match { + 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 int - bucket.distance() as int; + + if (ib as int) < robin_ib { + // Found a luckier bucket than me. Better steal his spot. + return robin_hood(bucket, robin_ib as uint, hash, k, v); + } + + probe = bucket.next(); + assert!(probe.index() != ib + size + 1); + } + } + + /// Retrieves a mutable value for the given key. + /// See [`find_mut`](../trait.MutableMap.html#tymethod.find_mut) for a non-panicking + /// alternative. + /// + /// # Failure + /// + /// Fails if the key is not present. + /// + /// # Example + /// + /// ``` + /// # #![allow(deprecated)] + /// use std::collections::HashMap; + /// + /// let mut map = HashMap::new(); + /// map.insert("a", 1i); + /// { + /// // val will freeze map to prevent usage during its lifetime + /// let val = map.get_mut(&"a"); + /// *val = 40; + /// } + /// assert_eq!(map["a"], 40); + /// + /// // A more direct way could be: + /// *map.get_mut(&"a") = -2; + /// assert_eq!(map["a"], -2); + /// ``` + #[deprecated = "use indexing instead: `&mut map[key]`"] + pub fn get_mut<'a>(&'a mut self, k: &K) -> &'a mut V { + &mut self[*k] + } + + /// Return true if the map contains a value for the specified key, + /// using equivalence. + /// + /// See [pop_equiv](#method.pop_equiv) for an extended example. + pub fn contains_key_equiv<Sized? Q: Hash<S> + Equiv<K>>(&self, key: &Q) -> bool { + self.search_equiv(key).is_some() + } + + /// Return the value corresponding to the key in the map, using + /// equivalence. + /// + /// See [pop_equiv](#method.pop_equiv) for an extended example. + pub fn find_equiv<'a, Sized? Q: Hash<S> + Equiv<K>>(&'a self, k: &Q) -> Option<&'a V> { + match self.search_equiv(k) { + None => None, + Some(bucket) => { + let (_, v_ref) = bucket.into_refs(); + Some(v_ref) + } + } + } + + /// Remove an equivalent key from the map, returning the value at the + /// key if the key was previously in the map. + /// + /// # Example + /// + /// This is a slightly silly example where we define the number's + /// parity as the equivalence class. It is important that the + /// values hash the same, which is why we implement `Hash`. + /// + /// ``` + /// use std::collections::HashMap; + /// use std::hash::Hash; + /// use std::hash::sip::SipState; + /// + /// #[deriving(Eq, PartialEq)] + /// struct EvenOrOdd { + /// num: uint + /// }; + /// + /// impl Hash for EvenOrOdd { + /// fn hash(&self, state: &mut SipState) { + /// let parity = self.num % 2; + /// parity.hash(state); + /// } + /// } + /// + /// impl Equiv<EvenOrOdd> for EvenOrOdd { + /// fn equiv(&self, other: &EvenOrOdd) -> bool { + /// self.num % 2 == other.num % 2 + /// } + /// } + /// + /// let mut map = HashMap::new(); + /// map.insert(EvenOrOdd { num: 3 }, "foo"); + /// + /// assert!(map.contains_key_equiv(&EvenOrOdd { num: 1 })); + /// assert!(!map.contains_key_equiv(&EvenOrOdd { num: 4 })); + /// + /// assert_eq!(map.find_equiv(&EvenOrOdd { num: 5 }), Some(&"foo")); + /// assert_eq!(map.find_equiv(&EvenOrOdd { num: 2 }), None); + /// + /// assert_eq!(map.pop_equiv(&EvenOrOdd { num: 1 }), Some("foo")); + /// assert_eq!(map.pop_equiv(&EvenOrOdd { num: 2 }), None); + /// + /// ``` + #[experimental] + pub fn pop_equiv<Sized? Q:Hash<S> + Equiv<K>>(&mut self, k: &Q) -> Option<V> { + if self.table.size() == 0 { + return None + } + + let potential_new_size = self.table.size() - 1; + self.make_some_room(potential_new_size); + + match self.search_equiv_mut(k) { + Some(bucket) => { + let (_k, val) = pop_internal(bucket); + Some(val) + } + _ => None + } + } + + /// An iterator visiting all keys in arbitrary order. + /// Iterator element type is `&'a K`. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashMap; + /// + /// let mut map = HashMap::new(); + /// map.insert("a", 1i); + /// map.insert("b", 2); + /// map.insert("c", 3); + /// + /// for key in map.keys() { + /// println!("{}", key); + /// } + /// ``` + pub fn keys(&self) -> Keys<K, V> { + self.iter().map(|(k, _v)| k) + } + + /// An iterator visiting all values in arbitrary order. + /// Iterator element type is `&'a V`. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashMap; + /// + /// let mut map = HashMap::new(); + /// map.insert("a", 1i); + /// map.insert("b", 2); + /// map.insert("c", 3); + /// + /// for key in map.values() { + /// println!("{}", key); + /// } + /// ``` + pub fn values(&self) -> Values<K, V> { + self.iter().map(|(_k, v)| v) + } + + /// An iterator visiting all key-value pairs in arbitrary order. + /// Iterator element type is `(&'a K, &'a V)`. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashMap; + /// + /// let mut map = HashMap::new(); + /// map.insert("a", 1i); + /// map.insert("b", 2); + /// map.insert("c", 3); + /// + /// for (key, val) in map.iter() { + /// println!("key: {} val: {}", key, val); + /// } + /// ``` + pub fn iter(&self) -> Entries<K, V> { + Entries { 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)`. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashMap; + /// + /// let mut map = HashMap::new(); + /// map.insert("a", 1i); + /// 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); + /// } + /// ``` + pub fn iter_mut(&mut self) -> MutEntries<K, V> { + MutEntries { inner: self.table.iter_mut() } + } + + /// 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. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashMap; + /// + /// let mut map = HashMap::new(); + /// map.insert("a", 1i); + /// map.insert("b", 2); + /// map.insert("c", 3); + /// + /// // Not possible with .iter() + /// let vec: Vec<(&str, int)> = map.into_iter().collect(); + /// ``` + pub fn into_iter(self) -> MoveEntries<K, V> { + MoveEntries { + inner: self.table.into_iter().map(|(_, k, v)| (k, v)) + } + } + + /// Gets the given key's corresponding entry in the map for in-place manipulation + pub fn entry<'a>(&'a mut self, key: K) -> Entry<'a, K, V> { + // Gotta resize now, and we don't know which direction, so try both? + let size = self.table.size(); + self.make_some_room(size + 1); + if size > 0 { + self.make_some_room(size - 1); + } + + let hash = self.make_hash(&key); + search_entry_hashed(&mut self.table, hash, key) + } + + /// Return the number of elements in the map. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashMap; + /// + /// let mut a = HashMap::new(); + /// assert_eq!(a.len(), 0); + /// a.insert(1u, "a"); + /// assert_eq!(a.len(), 1); + /// ``` + pub fn len(&self) -> uint { self.table.size() } + + /// Return true if the map contains no elements. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashMap; + /// + /// let mut a = HashMap::new(); + /// assert!(a.is_empty()); + /// a.insert(1u, "a"); + /// assert!(!a.is_empty()); + /// ``` + #[inline] + pub fn is_empty(&self) -> bool { self.len() == 0 } + + /// Clears the map, removing all key-value pairs. Keeps the allocated memory + /// for reuse. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashMap; + /// + /// let mut a = HashMap::new(); + /// a.insert(1u, "a"); + /// a.clear(); + /// assert!(a.is_empty()); + /// ``` + pub fn clear(&mut self) { + // Prevent reallocations from happening from now on. Makes it possible + // for the map to be reused but has a downside: reserves permanently. + self.resize_policy.reserve(self.table.size()); + + let cap = self.table.capacity(); + let mut buckets = Bucket::first(&mut self.table); + + while buckets.index() != cap { + buckets = match buckets.peek() { + Empty(b) => b.next(), + Full(full) => { + let (b, _, _) = full.take(); + b.next() + } + }; + } + } + + /// Returns a reference to the value corresponding to the key. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashMap; + /// + /// let mut map = HashMap::new(); + /// map.insert(1u, "a"); + /// assert_eq!(map.find(&1), Some(&"a")); + /// assert_eq!(map.find(&2), None); + /// ``` + pub fn find<'a>(&'a self, k: &K) -> Option<&'a V> { + self.search(k).map(|bucket| { + let (_, v) = bucket.into_refs(); + v + }) + } + + /// Returns true if the map contains a value for the specified key. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashMap; + /// + /// let mut map = HashMap::new(); + /// map.insert(1u, "a"); + /// assert_eq!(map.contains_key(&1), true); + /// assert_eq!(map.contains_key(&2), false); + /// ``` + pub fn contains_key(&self, k: &K) -> bool { + self.search(k).is_some() + } + + /// Returns a mutable reference to the value corresponding to the key. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashMap; + /// + /// let mut map = HashMap::new(); + /// map.insert(1u, "a"); + /// match map.find_mut(&1) { + /// Some(x) => *x = "b", + /// None => (), + /// } + /// assert_eq!(map[1], "b"); + /// ``` + pub fn find_mut<'a>(&'a mut self, k: &K) -> Option<&'a mut V> { + match self.search_mut(k) { + Some(bucket) => { + let (_, v) = bucket.into_mut_refs(); + Some(v) + } + _ => None + } + } + + /// Inserts a key-value pair into the map. An existing value for a + /// key is replaced by the new value. Returns `true` if the key did + /// not already exist in the map. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashMap; + /// + /// let mut map = HashMap::new(); + /// assert_eq!(map.insert(2u, "value"), true); + /// assert_eq!(map.insert(2, "value2"), false); + /// assert_eq!(map[2], "value2"); + /// ``` + #[inline] + pub fn insert(&mut self, key: K, value: V) -> bool { + self.swap(key, value).is_none() + } + + /// Removes a key-value pair from the map. Returns `true` if the key + /// was present in the map. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashMap; + /// + /// let mut map = HashMap::new(); + /// assert_eq!(map.remove(&1u), false); + /// map.insert(1, "a"); + /// assert_eq!(map.remove(&1), true); + /// ``` + #[inline] + pub fn remove(&mut self, key: &K) -> bool { + self.pop(key).is_some() + } + + /// Inserts a key-value pair from the map. If the key already had a value + /// present in the map, that value is returned. Otherwise, `None` is returned. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashMap; + /// + /// let mut map = HashMap::new(); + /// assert_eq!(map.swap(37u, "a"), None); + /// assert_eq!(map.is_empty(), false); + /// + /// map.insert(37, "b"); + /// assert_eq!(map.swap(37, "c"), Some("b")); + /// assert_eq!(map[37], "c"); + /// ``` + pub fn swap(&mut self, k: K, v: V) -> Option<V> { + let hash = self.make_hash(&k); + let potential_new_size = self.table.size() + 1; + self.make_some_room(potential_new_size); + + 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. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashMap; + /// + /// let mut map = HashMap::new(); + /// map.insert(1u, "a"); + /// assert_eq!(map.pop(&1), Some("a")); + /// assert_eq!(map.pop(&1), None); + /// ``` + pub fn pop(&mut self, k: &K) -> Option<V> { + if self.table.size() == 0 { + return None + } + + let potential_new_size = self.table.size() - 1; + self.make_some_room(potential_new_size); + + self.search_mut(k).map(|bucket| { + let (_k, val) = pop_internal(bucket); + val + }) + } +} + +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 + }; + + if bucket.hash() == hash { + let is_eq = { + let (bucket_k, _) = bucket.read(); + k == *bucket_k + }; + + if is_eq { + return Occupied(OccupiedEntry{ + elem: bucket, + }); + } + } + + let robin_ib = bucket.index() as int - bucket.distance() as int; + + if (ib as int) < 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 uint), + }); + } + + probe = bucket.next(); + assert!(probe.index() != ib + size + 1); + } +} + +impl<K: Eq + Hash<S>, V: Clone, S, H: Hasher<S>> HashMap<K, V, H> { + /// Return a copy of the value corresponding to the key. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashMap; + /// + /// let mut map: HashMap<uint, String> = HashMap::new(); + /// map.insert(1u, "foo".to_string()); + /// let s: String = map.find_copy(&1).unwrap(); + /// ``` + pub fn find_copy(&self, k: &K) -> Option<V> { + self.find(k).map(|v| (*v).clone()) + } + + /// Return a copy of the value corresponding to the key. + /// + /// # Failure + /// + /// Fails if the key is not present. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashMap; + /// + /// let mut map: HashMap<uint, String> = HashMap::new(); + /// map.insert(1u, "foo".to_string()); + /// let s: String = map.get_copy(&1); + /// ``` + pub fn get_copy(&self, k: &K) -> V { + self[*k].clone() + } +} + +impl<K: Eq + Hash<S>, V: PartialEq, S, H: Hasher<S>> PartialEq for HashMap<K, V, H> { + fn eq(&self, other: &HashMap<K, V, H>) -> bool { + if self.len() != other.len() { return false; } + + self.iter().all(|(key, value)| + other.find(key).map_or(false, |v| *value == *v) + ) + } +} + +impl<K: Eq + Hash<S>, V: Eq, S, H: Hasher<S>> Eq for HashMap<K, V, H> {} + +impl<K: Eq + Hash<S> + Show, V: Show, S, H: Hasher<S>> Show for HashMap<K, V, H> { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + try!(write!(f, "{{")); + + for (i, (k, v)) in self.iter().enumerate() { + if i != 0 { try!(write!(f, ", ")); } + try!(write!(f, "{}: {}", *k, *v)); + } + + write!(f, "}}") + } +} + +impl<K: Eq + Hash<S>, V, S, H: Hasher<S> + Default> Default for HashMap<K, V, H> { + fn default() -> HashMap<K, V, H> { + HashMap::with_hasher(Default::default()) + } +} + +impl<K: Eq + Hash<S>, V, S, H: Hasher<S>> Index<K, V> for HashMap<K, V, H> { + #[inline] + fn index<'a>(&'a self, index: &K) -> &'a V { + self.find(index).expect("no entry found for key") + } +} + +impl<K: Eq + Hash<S>, V, S, H: Hasher<S>> IndexMut<K, V> for HashMap<K, V, H> { + #[inline] + fn index_mut<'a>(&'a mut self, index: &K) -> &'a mut V { + match self.find_mut(index) { + Some(v) => v, + None => panic!("no entry found for key") + } + } +} + +/// HashMap iterator +pub struct Entries<'a, K: 'a, V: 'a> { + inner: table::Entries<'a, K, V> +} + +/// HashMap mutable values iterator +pub struct MutEntries<'a, K: 'a, V: 'a> { + inner: table::MutEntries<'a, K, V> +} + +/// HashMap move iterator +pub struct MoveEntries<K, V> { + inner: iter::Map<'static, (SafeHash, K, V), (K, V), table::MoveEntries<K, V>> +} + +/// A view into a single occupied location in a HashMap +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 +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 +pub enum Entry<'a, K:'a, V:'a> { + /// An occupied Entry + Occupied(OccupiedEntry<'a, K, V>), + /// A vacant Entry + 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>, uint), + /// The index is genuinely vacant + NoElem(EmptyBucket<K, V, M>), +} + +impl<'a, K, V> Iterator<(&'a K, &'a V)> for Entries<'a, K, V> { + #[inline] + fn next(&mut self) -> Option<(&'a K, &'a V)> { + self.inner.next() + } + #[inline] + fn size_hint(&self) -> (uint, Option<uint>) { + self.inner.size_hint() + } +} + +impl<'a, K, V> Iterator<(&'a K, &'a mut V)> for MutEntries<'a, K, V> { + #[inline] + fn next(&mut self) -> Option<(&'a K, &'a mut V)> { + self.inner.next() + } + #[inline] + fn size_hint(&self) -> (uint, Option<uint>) { + self.inner.size_hint() + } +} + +impl<K, V> Iterator<(K, V)> for MoveEntries<K, V> { + #[inline] + fn next(&mut self) -> Option<(K, V)> { + self.inner.next() + } + #[inline] + fn size_hint(&self) -> (uint, Option<uint>) { + self.inner.size_hint() + } +} + +impl<'a, K, V> OccupiedEntry<'a, K, V> { + /// Gets a reference to the value in the entry + pub fn get(&self) -> &V { + let (_, v) = self.elem.read(); + v + } + + /// Gets a mutable reference to the value in the entry + pub fn get_mut(&mut self) -> &mut V { + let (_, v) = self.elem.read_mut(); + v + } + + /// Converts the OccupiedEntry into a mutable reference to the value in the entry + /// with a lifetime bound to the map itself + pub fn into_mut(self) -> &'a mut V { + let (_, v) = self.elem.into_mut_refs(); + v + } + + /// Sets the value of the entry, and returns the entry's old value + pub fn set(&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 + pub fn take(self) -> V { + let (_, _, v) = self.elem.take(); + v + } +} + +impl<'a, K, V> VacantEntry<'a, K, V> { + /// Sets the value of the entry with the VacantEntry's key, + /// and returns a mutable reference to it + pub fn set(self, value: V) -> &'a mut V { + match self.elem { + NeqElem(bucket, ib) => { + robin_hood(bucket, ib, self.hash, self.key, value) + } + NoElem(bucket) => { + let full = bucket.put(self.hash, self.key, value); + let (_, v) = full.into_mut_refs(); + v + } + } + } +} + +/// HashMap keys iterator +pub type Keys<'a, K, V> = + iter::Map<'static, (&'a K, &'a V), &'a K, Entries<'a, K, V>>; + +/// HashMap values iterator +pub type Values<'a, K, V> = + iter::Map<'static, (&'a K, &'a V), &'a V, Entries<'a, K, V>>; + +impl<K: Eq + Hash<S>, V, S, H: Hasher<S> + Default> FromIterator<(K, V)> for HashMap<K, V, H> { + fn from_iter<T: Iterator<(K, V)>>(iter: T) -> HashMap<K, V, H> { + let (lower, _) = iter.size_hint(); + let mut map = HashMap::with_capacity_and_hasher(lower, Default::default()); + map.extend(iter); + map + } +} + +impl<K: Eq + Hash<S>, V, S, H: Hasher<S> + Default> Extendable<(K, V)> for HashMap<K, V, H> { + fn extend<T: Iterator<(K, V)>>(&mut self, mut iter: T) { + for (k, v) in iter { + self.insert(k, v); + } + } +} + +#[cfg(test)] +mod test_map { + use prelude::*; + + use super::HashMap; + use super::{Occupied, Vacant}; + use cmp::Equiv; + use hash; + use iter::{Iterator,range_inclusive,range_step_inclusive}; + use cell::RefCell; + + struct KindaIntLike(int); + + impl Equiv<int> for KindaIntLike { + fn equiv(&self, other: &int) -> bool { + let KindaIntLike(this) = *self; + this == *other + } + } + impl<S: hash::Writer> hash::Hash<S> for KindaIntLike { + fn hash(&self, state: &mut S) { + let KindaIntLike(this) = *self; + this.hash(state) + } + } + + #[test] + fn test_create_capacity_zero() { + let mut m = HashMap::with_capacity(0); + + assert!(m.insert(1i, 1i)); + + 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(1i, 2i)); + assert_eq!(m.len(), 1); + assert!(m.insert(2i, 4i)); + assert_eq!(m.len(), 2); + assert_eq!(*m.find(&1).unwrap(), 2); + assert_eq!(*m.find(&2).unwrap(), 4); + } + + local_data_key!(drop_vector: RefCell<Vec<int>>) + + #[deriving(Hash, PartialEq, Eq)] + struct Dropable { + k: uint + } + + impl Dropable { + fn new(k: uint) -> Dropable { + let v = drop_vector.get().unwrap(); + v.borrow_mut().as_mut_slice()[k] += 1; + + Dropable { k: k } + } + } + + impl Drop for Dropable { + fn drop(&mut self) { + let v = drop_vector.get().unwrap(); + v.borrow_mut().as_mut_slice()[self.k] -= 1; + } + } + + impl Clone for Dropable { + fn clone(&self) -> Dropable { + Dropable::new(self.k) + } + } + + #[test] + fn test_drops() { + drop_vector.replace(Some(RefCell::new(Vec::from_elem(200, 0i)))); + + { + let mut m = HashMap::new(); + + let v = drop_vector.get().unwrap(); + for i in range(0u, 200) { + assert_eq!(v.borrow().as_slice()[i], 0); + } + drop(v); + + for i in range(0u, 100) { + let d1 = Dropable::new(i); + let d2 = Dropable::new(i+100); + m.insert(d1, d2); + } + + let v = drop_vector.get().unwrap(); + for i in range(0u, 200) { + assert_eq!(v.borrow().as_slice()[i], 1); + } + drop(v); + + for i in range(0u, 50) { + let k = Dropable::new(i); + let v = m.pop(&k); + + assert!(v.is_some()); + + let v = drop_vector.get().unwrap(); + assert_eq!(v.borrow().as_slice()[i], 1); + assert_eq!(v.borrow().as_slice()[i+100], 1); + } + + let v = drop_vector.get().unwrap(); + for i in range(0u, 50) { + assert_eq!(v.borrow().as_slice()[i], 0); + assert_eq!(v.borrow().as_slice()[i+100], 0); + } + + for i in range(50u, 100) { + assert_eq!(v.borrow().as_slice()[i], 1); + assert_eq!(v.borrow().as_slice()[i+100], 1); + } + } + + let v = drop_vector.get().unwrap(); + for i in range(0u, 200) { + assert_eq!(v.borrow().as_slice()[i], 0); + } + } + + #[test] + fn test_move_iter_drops() { + drop_vector.replace(Some(RefCell::new(Vec::from_elem(200, 0i)))); + + let hm = { + let mut hm = HashMap::new(); + + let v = drop_vector.get().unwrap(); + for i in range(0u, 200) { + assert_eq!(v.borrow().as_slice()[i], 0); + } + drop(v); + + for i in range(0u, 100) { + let d1 = Dropable::new(i); + let d2 = Dropable::new(i+100); + hm.insert(d1, d2); + } + + let v = drop_vector.get().unwrap(); + for i in range(0u, 200) { + assert_eq!(v.borrow().as_slice()[i], 1); + } + drop(v); + + hm + }; + + // By the way, ensure that cloning doesn't screw up the dropping. + drop(hm.clone()); + + { + let mut half = hm.into_iter().take(50); + + let v = drop_vector.get().unwrap(); + for i in range(0u, 200) { + assert_eq!(v.borrow().as_slice()[i], 1); + } + drop(v); + + for _ in half {} + + let v = drop_vector.get().unwrap(); + let nk = range(0u, 100).filter(|&i| { + v.borrow().as_slice()[i] == 1 + }).count(); + + let nv = range(0u, 100).filter(|&i| { + v.borrow().as_slice()[i+100] == 1 + }).count(); + + assert_eq!(nk, 50); + assert_eq!(nv, 50); + }; + + let v = drop_vector.get().unwrap(); + for i in range(0u, 200) { + assert_eq!(v.borrow().as_slice()[i], 0); + } + } + + #[test] + fn test_empty_pop() { + let mut m: HashMap<int, bool> = HashMap::new(); + assert_eq!(m.pop(&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 range(0i, 10) { + assert!(m.is_empty()); + + for i in range_inclusive(1i, 1000) { + assert!(m.insert(i, i)); + + for j in range_inclusive(1, i) { + let r = m.find(&j); + assert_eq!(r, Some(&j)); + } + + for j in range_inclusive(i+1, 1000) { + let r = m.find(&j); + assert_eq!(r, None); + } + } + + for i in range_inclusive(1001i, 2000) { + assert!(!m.contains_key(&i)); + } + + // remove forwards + for i in range_inclusive(1i, 1000) { + assert!(m.remove(&i)); + + 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(1i, 1000) { + assert!(!m.contains_key(&i)); + } + + for i in range_inclusive(1i, 1000) { + assert!(m.insert(i, i)); + } + + // remove backwards + for i in range_step_inclusive(1000i, 1, -1) { + assert!(m.remove(&i)); + + 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(1i, 12i)); + assert!(m.insert(2i, 8i)); + assert!(m.insert(5i, 14i)); + let new = 100; + match m.find_mut(&5) { + None => panic!(), Some(x) => *x = new + } + assert_eq!(m.find(&5), Some(&new)); + } + + #[test] + fn test_insert_overwrite() { + let mut m = HashMap::new(); + assert!(m.insert(1i, 2i)); + assert_eq!(*m.find(&1).unwrap(), 2); + assert!(!m.insert(1i, 3i)); + assert_eq!(*m.find(&1).unwrap(), 3); + } + + #[test] + fn test_insert_conflicts() { + let mut m = HashMap::with_capacity(4); + assert!(m.insert(1i, 2i)); + assert!(m.insert(5i, 3i)); + assert!(m.insert(9i, 4i)); + assert_eq!(*m.find(&9).unwrap(), 4); + assert_eq!(*m.find(&5).unwrap(), 3); + assert_eq!(*m.find(&1).unwrap(), 2); + } + + #[test] + fn test_conflict_remove() { + let mut m = HashMap::with_capacity(4); + assert!(m.insert(1i, 2i)); + assert_eq!(*m.find(&1).unwrap(), 2); + assert!(m.insert(5, 3)); + assert_eq!(*m.find(&1).unwrap(), 2); + assert_eq!(*m.find(&5).unwrap(), 3); + assert!(m.insert(9, 4)); + assert_eq!(*m.find(&1).unwrap(), 2); + assert_eq!(*m.find(&5).unwrap(), 3); + assert_eq!(*m.find(&9).unwrap(), 4); + assert!(m.remove(&1)); + assert_eq!(*m.find(&9).unwrap(), 4); + assert_eq!(*m.find(&5).unwrap(), 3); + } + + #[test] + fn test_is_empty() { + let mut m = HashMap::with_capacity(4); + assert!(m.insert(1i, 2i)); + assert!(!m.is_empty()); + assert!(m.remove(&1)); + assert!(m.is_empty()); + } + + #[test] + fn test_pop() { + let mut m = HashMap::new(); + m.insert(1i, 2i); + assert_eq!(m.pop(&1), Some(2)); + assert_eq!(m.pop(&1), None); + } + + #[test] + #[allow(experimental)] + fn test_pop_equiv() { + let mut m = HashMap::new(); + m.insert(1i, 2i); + assert_eq!(m.pop_equiv(&KindaIntLike(1)), Some(2)); + assert_eq!(m.pop_equiv(&KindaIntLike(1)), None); + } + + #[test] + fn test_swap() { + let mut m = HashMap::new(); + assert_eq!(m.swap(1i, 2i), None); + assert_eq!(m.swap(1i, 3i), Some(2)); + assert_eq!(m.swap(1i, 4i), Some(3)); + } + + #[test] + fn test_iterate() { + let mut m = HashMap::with_capacity(4); + for i in range(0u, 32) { + assert!(m.insert(i, i*2)); + } + assert_eq!(m.len(), 32); + + let mut observed: u32 = 0; + + for (k, v) in m.iter() { + assert_eq!(*v, *k * 2); + observed |= 1 << *k; + } + assert_eq!(observed, 0xFFFF_FFFF); + } + + #[test] + fn test_keys() { + let vec = vec![(1i, 'a'), (2i, 'b'), (3i, 'c')]; + let map = vec.into_iter().collect::<HashMap<int, char>>(); + let keys = map.keys().map(|&k| k).collect::<Vec<int>>(); + assert_eq!(keys.len(), 3); + assert!(keys.contains(&1)); + assert!(keys.contains(&2)); + assert!(keys.contains(&3)); + } + + #[test] + fn test_values() { + let vec = vec![(1i, 'a'), (2i, 'b'), (3i, 'c')]; + let map = vec.into_iter().collect::<HashMap<int, char>>(); + let values = map.values().map(|&v| v).collect::<Vec<char>>(); + assert_eq!(values.len(), 3); + assert!(values.contains(&'a')); + assert!(values.contains(&'b')); + assert!(values.contains(&'c')); + } + + #[test] + fn test_find() { + let mut m = HashMap::new(); + assert!(m.find(&1i).is_none()); + m.insert(1i, 2i); + match m.find(&1) { + None => panic!(), + Some(v) => assert_eq!(*v, 2) + } + } + + #[test] + fn test_find_copy() { + let mut m = HashMap::new(); + assert!(m.find(&1i).is_none()); + + for i in range(1i, 10000) { + m.insert(i, i + 7); + match m.find_copy(&i) { + None => panic!(), + Some(v) => assert_eq!(v, i + 7) + } + for j in range(1i, i/100) { + match m.find_copy(&j) { + None => panic!(), + Some(v) => assert_eq!(v, j + 7) + } + } + } + } + + #[test] + fn test_eq() { + let mut m1 = HashMap::new(); + m1.insert(1i, 2i); + m1.insert(2i, 3i); + m1.insert(3i, 4i); + + let mut m2 = HashMap::new(); + m2.insert(1i, 2i); + m2.insert(2i, 3i); + + assert!(m1 != m2); + + m2.insert(3i, 4i); + + assert_eq!(m1, m2); + } + + #[test] + fn test_show() { + let mut map: HashMap<int, int> = HashMap::new(); + let empty: HashMap<int, int> = HashMap::new(); + + map.insert(1i, 2i); + map.insert(3i, 4i); + + let map_str = format!("{}", map); + + assert!(map_str == "{1: 2, 3: 4}".to_string() || map_str == "{3: 4, 1: 2}".to_string()); + assert_eq!(format!("{}", empty), "{}".to_string()); + } + + #[test] + fn test_expand() { + let mut m = HashMap::new(); + + assert_eq!(m.len(), 0); + assert!(m.is_empty()); + + let mut i = 0u; + 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_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 * 2); + let cap = m.table.capacity(); + + assert_eq!(cap, initial_cap * 2); + + let mut i = 0u; + for _ in range(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 range(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 range(0, cap / 2 - 1) { + i -= 1; + m.remove(&i); + assert_eq!(m.table.capacity(), new_cap); + } + // A little more than one quarter full. + // Shrinking starts as we remove more elements: + for _ in range(0, cap / 2 - 1) { + i -= 1; + m.remove(&i); + } + + assert_eq!(m.len(), i); + assert!(!m.is_empty()); + assert_eq!(m.table.capacity(), cap); + } + + #[test] + fn test_find_equiv() { + let mut m = HashMap::new(); + + let (foo, bar, baz) = (1i,2i,3i); + m.insert("foo".to_string(), foo); + m.insert("bar".to_string(), bar); + m.insert("baz".to_string(), baz); + + + assert_eq!(m.find_equiv("foo"), Some(&foo)); + assert_eq!(m.find_equiv("bar"), Some(&bar)); + assert_eq!(m.find_equiv("baz"), Some(&baz)); + + assert_eq!(m.find_equiv("qux"), None); + } + + #[test] + fn test_from_iter() { + let xs = [(1i, 1i), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)]; + + let map: HashMap<int, int> = xs.iter().map(|&x| x).collect(); + + for &(k, v) in xs.iter() { + assert_eq!(map.find(&k), Some(&v)); + } + } + + #[test] + fn test_size_hint() { + let xs = [(1i, 1i), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)]; + + let map: HashMap<int, int> = xs.iter().map(|&x| x).collect(); + + let mut iter = map.iter(); + + for _ in iter.by_ref().take(3) {} + + assert_eq!(iter.size_hint(), (3, Some(3))); + } + + #[test] + fn test_mut_size_hint() { + let xs = [(1i, 1i), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)]; + + let mut map: HashMap<int, int> = xs.iter().map(|&x| x).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_index() { + let mut map: HashMap<int, int> = HashMap::new(); + + map.insert(1, 2); + map.insert(2, 1); + map.insert(3, 4); + + assert_eq!(map[2], 1); + } + + #[test] + #[should_fail] + fn test_index_nonexistent() { + let mut map: HashMap<int, int> = HashMap::new(); + + map.insert(1, 2); + map.insert(2, 1); + map.insert(3, 4); + + map[4]; + } + + #[test] + fn test_entry(){ + let xs = [(1i, 10i), (2, 20), (3, 30), (4, 40), (5, 50), (6, 60)]; + + let mut map: HashMap<int, int> = xs.iter().map(|&x| x).collect(); + + // Existing key (insert) + match map.entry(1) { + Vacant(_) => unreachable!(), + Occupied(mut view) => { + assert_eq!(view.get(), &10); + assert_eq!(view.set(100), 10); + } + } + assert_eq!(map.find(&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.find(&2).unwrap(), &200); + assert_eq!(map.len(), 6); + + // Existing key (take) + match map.entry(3) { + Vacant(_) => unreachable!(), + Occupied(view) => { + assert_eq!(view.take(), 30); + } + } + assert_eq!(map.find(&3), None); + assert_eq!(map.len(), 5); + + + // Inexistent key (insert) + match map.entry(10) { + Occupied(_) => unreachable!(), + Vacant(view) => { + assert_eq!(*view.set(1000), 1000); + } + } + assert_eq!(map.find(&10).unwrap(), &1000); + assert_eq!(map.len(), 6); + } +} diff --git a/src/libstd/collections/hash/mod.rs b/src/libstd/collections/hash/mod.rs new file mode 100644 index 00000000000..ee3fc1e6ac3 --- /dev/null +++ b/src/libstd/collections/hash/mod.rs @@ -0,0 +1,16 @@ +// Copyright 2014 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or +// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license +// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +//! Unordered containers, implemented as hash-tables + +mod bench; +pub mod map; +pub mod set; +mod table; diff --git a/src/libstd/collections/hash/set.rs b/src/libstd/collections/hash/set.rs new file mode 100644 index 00000000000..823bd49d7a6 --- /dev/null +++ b/src/libstd/collections/hash/set.rs @@ -0,0 +1,834 @@ +// Copyright 2014 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or +// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license +// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. +// +// ignore-lexer-test FIXME #15883 + +use clone::Clone; +use cmp::{Eq, Equiv, PartialEq}; +use core::kinds::Sized; +use default::Default; +use fmt::Show; +use fmt; +use hash::{Hash, Hasher, RandomSipHasher}; +use iter::{Iterator, FromIterator, FilterMap, Chain, Repeat, Zip, Extendable}; +use iter; +use option::{Some, None}; +use result::{Ok, Err}; + +use super::map::{HashMap, Entries, MoveEntries, INITIAL_CAPACITY}; + + +// Future Optimization (FIXME!) +// ============================= +// +// Iteration over zero sized values is a noop. There is no need +// for `bucket.val` in the case of HashSet. I suppose we would need HKT +// to get rid of it properly. + +/// An implementation of a hash set using the underlying representation of a +/// HashMap where the value is (). As with the `HashMap` type, a `HashSet` +/// requires that the elements implement the `Eq` and `Hash` traits. +/// +/// # Example +/// +/// ``` +/// use std::collections::HashSet; +/// // Type inference lets us omit an explicit type signature (which +/// // would be `HashSet<&str>` in this example). +/// let mut books = HashSet::new(); +/// +/// // Add some books. +/// books.insert("A Dance With Dragons"); +/// books.insert("To Kill a Mockingbird"); +/// books.insert("The Odyssey"); +/// books.insert("The Great Gatsby"); +/// +/// // Check for a specific one. +/// if !books.contains(&("The Winds of Winter")) { +/// println!("We have {} books, but The Winds of Winter ain't one.", +/// books.len()); +/// } +/// +/// // Remove a book. +/// books.remove(&"The Odyssey"); +/// +/// // Iterate over everything. +/// for book in books.iter() { +/// println!("{}", *book); +/// } +/// ``` +/// +/// The easiest way to use `HashSet` with a custom type is to derive +/// `Eq` and `Hash`. We must also derive `PartialEq`, this will in the +/// future be implied by `Eq`. +/// +/// ``` +/// use std::collections::HashSet; +/// #[deriving(Hash, Eq, PartialEq, Show)] +/// struct Viking<'a> { +/// name: &'a str, +/// power: uint, +/// } +/// +/// let mut vikings = HashSet::new(); +/// +/// vikings.insert(Viking { name: "Einar", power: 9u }); +/// vikings.insert(Viking { name: "Einar", power: 9u }); +/// vikings.insert(Viking { name: "Olaf", power: 4u }); +/// vikings.insert(Viking { name: "Harald", power: 8u }); +/// +/// // Use derived implementation to print the vikings. +/// for x in vikings.iter() { +/// println!("{}", x); +/// } +/// ``` +#[deriving(Clone)] +pub struct HashSet<T, H = RandomSipHasher> { + map: HashMap<T, (), H> +} + +impl<T: Hash + Eq> HashSet<T, RandomSipHasher> { + /// Create an empty HashSet. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashSet; + /// let mut set: HashSet<int> = HashSet::new(); + /// ``` + #[inline] + pub fn new() -> HashSet<T, RandomSipHasher> { + HashSet::with_capacity(INITIAL_CAPACITY) + } + + /// Create an empty HashSet with space for at least `n` elements in + /// the hash table. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashSet; + /// let mut set: HashSet<int> = HashSet::with_capacity(10); + /// ``` + #[inline] + pub fn with_capacity(capacity: uint) -> HashSet<T, RandomSipHasher> { + HashSet { map: HashMap::with_capacity(capacity) } + } +} + +impl<T: Eq + Hash<S>, S, H: Hasher<S>> HashSet<T, H> { + /// Creates a new empty hash set which will use the given hasher to hash + /// keys. + /// + /// The hash set is also created with the default initial capacity. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashSet; + /// use std::hash::sip::SipHasher; + /// + /// let h = SipHasher::new(); + /// let mut set = HashSet::with_hasher(h); + /// set.insert(2u); + /// ``` + #[inline] + pub fn with_hasher(hasher: H) -> HashSet<T, H> { + HashSet::with_capacity_and_hasher(INITIAL_CAPACITY, hasher) + } + + /// Create an empty HashSet with space for at least `capacity` + /// elements in the hash table, using `hasher` to hash the keys. + /// + /// Warning: `hasher` is normally randomly generated, and + /// is designed to allow `HashSet`s to be resistant to attacks that + /// cause many collisions and very poor performance. Setting it + /// manually using this function can expose a DoS attack vector. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashSet; + /// use std::hash::sip::SipHasher; + /// + /// let h = SipHasher::new(); + /// let mut set = HashSet::with_capacity_and_hasher(10u, h); + /// set.insert(1i); + /// ``` + #[inline] + pub fn with_capacity_and_hasher(capacity: uint, hasher: H) -> HashSet<T, H> { + HashSet { map: HashMap::with_capacity_and_hasher(capacity, hasher) } + } + + /// Reserve space for at least `n` elements in the hash table. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashSet; + /// let mut set: HashSet<int> = HashSet::new(); + /// set.reserve(10); + /// ``` + pub fn reserve(&mut self, n: uint) { + self.map.reserve(n) + } + + /// Returns true if the hash set contains a value equivalent to the + /// given query value. + /// + /// # Example + /// + /// This is a slightly silly example where we define the number's + /// parity as the equivalance class. It is important that the + /// values hash the same, which is why we implement `Hash`. + /// + /// ``` + /// use std::collections::HashSet; + /// use std::hash::Hash; + /// use std::hash::sip::SipState; + /// + /// #[deriving(Eq, PartialEq)] + /// struct EvenOrOdd { + /// num: uint + /// }; + /// + /// impl Hash for EvenOrOdd { + /// fn hash(&self, state: &mut SipState) { + /// let parity = self.num % 2; + /// parity.hash(state); + /// } + /// } + /// + /// impl Equiv<EvenOrOdd> for EvenOrOdd { + /// fn equiv(&self, other: &EvenOrOdd) -> bool { + /// self.num % 2 == other.num % 2 + /// } + /// } + /// + /// let mut set = HashSet::new(); + /// set.insert(EvenOrOdd { num: 3u }); + /// + /// assert!(set.contains_equiv(&EvenOrOdd { num: 3u })); + /// assert!(set.contains_equiv(&EvenOrOdd { num: 5u })); + /// assert!(!set.contains_equiv(&EvenOrOdd { num: 4u })); + /// assert!(!set.contains_equiv(&EvenOrOdd { num: 2u })); + /// + /// ``` + pub fn contains_equiv<Sized? Q: Hash<S> + Equiv<T>>(&self, value: &Q) -> bool { + self.map.contains_key_equiv(value) + } + + /// An iterator visiting all elements in arbitrary order. + /// Iterator element type is &'a T. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashSet; + /// let mut set = HashSet::new(); + /// set.insert("a"); + /// set.insert("b"); + /// + /// // Will print in an arbitrary order. + /// for x in set.iter() { + /// println!("{}", x); + /// } + /// ``` + pub fn iter<'a>(&'a self) -> SetItems<'a, T> { + self.map.keys() + } + + /// Deprecated: use `into_iter`. + #[deprecated = "use into_iter"] + pub fn move_iter(self) -> SetMoveItems<T> { + self.into_iter() + } + + /// Creates a consuming iterator, that is, one that moves each value out + /// of the set in arbitrary order. The set cannot be used after calling + /// this. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashSet; + /// let mut set = HashSet::new(); + /// set.insert("a".to_string()); + /// set.insert("b".to_string()); + /// + /// // Not possible to collect to a Vec<String> with a regular `.iter()`. + /// let v: Vec<String> = set.into_iter().collect(); + /// + /// // Will print in an arbitrary order. + /// for x in v.iter() { + /// println!("{}", x); + /// } + /// ``` + pub fn into_iter(self) -> SetMoveItems<T> { + self.map.into_iter().map(|(k, _)| k) + } + + /// Visit the values representing the difference. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashSet; + /// let a: HashSet<int> = [1i, 2, 3].iter().map(|&x| x).collect(); + /// let b: HashSet<int> = [4i, 2, 3, 4].iter().map(|&x| x).collect(); + /// + /// // Can be seen as `a - b`. + /// for x in a.difference(&b) { + /// println!("{}", x); // Print 1 + /// } + /// + /// let diff: HashSet<int> = a.difference(&b).map(|&x| x).collect(); + /// assert_eq!(diff, [1i].iter().map(|&x| x).collect()); + /// + /// // Note that difference is not symmetric, + /// // and `b - a` means something else: + /// let diff: HashSet<int> = b.difference(&a).map(|&x| x).collect(); + /// assert_eq!(diff, [4i].iter().map(|&x| x).collect()); + /// ``` + pub fn difference<'a>(&'a self, other: &'a HashSet<T, H>) -> SetAlgebraItems<'a, T, H> { + Repeat::new(other).zip(self.iter()) + .filter_map(|(other, elt)| { + if !other.contains(elt) { Some(elt) } else { None } + }) + } + + /// Visit the values representing the symmetric difference. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashSet; + /// let a: HashSet<int> = [1i, 2, 3].iter().map(|&x| x).collect(); + /// let b: HashSet<int> = [4i, 2, 3, 4].iter().map(|&x| x).collect(); + /// + /// // Print 1, 4 in arbitrary order. + /// for x in a.symmetric_difference(&b) { + /// println!("{}", x); + /// } + /// + /// let diff1: HashSet<int> = a.symmetric_difference(&b).map(|&x| x).collect(); + /// let diff2: HashSet<int> = b.symmetric_difference(&a).map(|&x| x).collect(); + /// + /// assert_eq!(diff1, diff2); + /// assert_eq!(diff1, [1i, 4].iter().map(|&x| x).collect()); + /// ``` + pub fn symmetric_difference<'a>(&'a self, other: &'a HashSet<T, H>) + -> Chain<SetAlgebraItems<'a, T, H>, SetAlgebraItems<'a, T, H>> { + self.difference(other).chain(other.difference(self)) + } + + /// Visit the values representing the intersection. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashSet; + /// let a: HashSet<int> = [1i, 2, 3].iter().map(|&x| x).collect(); + /// let b: HashSet<int> = [4i, 2, 3, 4].iter().map(|&x| x).collect(); + /// + /// // Print 2, 3 in arbitrary order. + /// for x in a.intersection(&b) { + /// println!("{}", x); + /// } + /// + /// let diff: HashSet<int> = a.intersection(&b).map(|&x| x).collect(); + /// assert_eq!(diff, [2i, 3].iter().map(|&x| x).collect()); + /// ``` + pub fn intersection<'a>(&'a self, other: &'a HashSet<T, H>) + -> SetAlgebraItems<'a, T, H> { + Repeat::new(other).zip(self.iter()) + .filter_map(|(other, elt)| { + if other.contains(elt) { Some(elt) } else { None } + }) + } + + /// Visit the values representing the union. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashSet; + /// let a: HashSet<int> = [1i, 2, 3].iter().map(|&x| x).collect(); + /// let b: HashSet<int> = [4i, 2, 3, 4].iter().map(|&x| x).collect(); + /// + /// // Print 1, 2, 3, 4 in arbitrary order. + /// for x in a.union(&b) { + /// println!("{}", x); + /// } + /// + /// let diff: HashSet<int> = a.union(&b).map(|&x| x).collect(); + /// assert_eq!(diff, [1i, 2, 3, 4].iter().map(|&x| x).collect()); + /// ``` + pub fn union<'a>(&'a self, other: &'a HashSet<T, H>) + -> Chain<SetItems<'a, T>, SetAlgebraItems<'a, T, H>> { + self.iter().chain(other.difference(self)) + } + + /// Return the number of elements in the set + /// + /// # Example + /// + /// ``` + /// use std::collections::HashSet; + /// + /// let mut v = HashSet::new(); + /// assert_eq!(v.len(), 0); + /// v.insert(1u); + /// assert_eq!(v.len(), 1); + /// ``` + pub fn len(&self) -> uint { self.map.len() } + + /// Returns true if the set contains no elements + /// + /// # Example + /// + /// ``` + /// use std::collections::HashSet; + /// + /// let mut v = HashSet::new(); + /// assert!(v.is_empty()); + /// v.insert(1u); + /// assert!(!v.is_empty()); + /// ``` + pub fn is_empty(&self) -> bool { self.map.len() == 0 } + + /// Clears the set, removing all values. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashSet; + /// + /// let mut v = HashSet::new(); + /// v.insert(1u); + /// v.clear(); + /// assert!(v.is_empty()); + /// ``` + pub fn clear(&mut self) { self.map.clear() } + + /// Returns `true` if the set contains a value. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashSet; + /// + /// let set: HashSet<uint> = [1, 2, 3].iter().map(|&x| x).collect(); + /// assert_eq!(set.contains(&1), true); + /// assert_eq!(set.contains(&4), false); + /// ``` + pub fn contains(&self, value: &T) -> bool { self.map.contains_key(value) } + + /// Returns `true` if the set has no elements in common with `other`. + /// This is equivalent to checking for an empty intersection. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashSet; + /// + /// let a: HashSet<uint> = [1, 2, 3].iter().map(|&x| x).collect(); + /// let mut b: HashSet<uint> = HashSet::new(); + /// + /// assert_eq!(a.is_disjoint(&b), true); + /// b.insert(4); + /// assert_eq!(a.is_disjoint(&b), true); + /// b.insert(1); + /// assert_eq!(a.is_disjoint(&b), false); + /// ``` + pub fn is_disjoint(&self, other: &HashSet<T, H>) -> bool { + self.iter().all(|v| !other.contains(v)) + } + + /// Returns `true` if the set is a subset of another. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashSet; + /// + /// let sup: HashSet<uint> = [1, 2, 3].iter().map(|&x| x).collect(); + /// let mut set: HashSet<uint> = HashSet::new(); + /// + /// assert_eq!(set.is_subset(&sup), true); + /// set.insert(2); + /// assert_eq!(set.is_subset(&sup), true); + /// set.insert(4); + /// assert_eq!(set.is_subset(&sup), false); + /// ``` + pub fn is_subset(&self, other: &HashSet<T, H>) -> bool { + self.iter().all(|v| other.contains(v)) + } + + /// Returns `true` if the set is a superset of another. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashSet; + /// + /// let sub: HashSet<uint> = [1, 2].iter().map(|&x| x).collect(); + /// let mut set: HashSet<uint> = HashSet::new(); + /// + /// assert_eq!(set.is_superset(&sub), false); + /// + /// set.insert(0); + /// set.insert(1); + /// assert_eq!(set.is_superset(&sub), false); + /// + /// set.insert(2); + /// assert_eq!(set.is_superset(&sub), true); + /// ``` + #[inline] + pub fn is_superset(&self, other: &HashSet<T, H>) -> bool { + other.is_subset(self) + } + + /// Adds a value to the set. Returns `true` if the value was not already + /// present in the set. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashSet; + /// + /// let mut set = HashSet::new(); + /// + /// assert_eq!(set.insert(2u), true); + /// assert_eq!(set.insert(2), false); + /// assert_eq!(set.len(), 1); + /// ``` + pub fn insert(&mut self, value: T) -> bool { self.map.insert(value, ()) } + + /// Removes a value from the set. Returns `true` if the value was + /// present in the set. + /// + /// # Example + /// + /// ``` + /// use std::collections::HashSet; + /// + /// let mut set = HashSet::new(); + /// + /// set.insert(2u); + /// assert_eq!(set.remove(&2), true); + /// assert_eq!(set.remove(&2), false); + /// ``` + pub fn remove(&mut self, value: &T) -> bool { self.map.remove(value) } +} + +impl<T: Eq + Hash<S>, S, H: Hasher<S>> PartialEq for HashSet<T, H> { + fn eq(&self, other: &HashSet<T, H>) -> bool { + if self.len() != other.len() { return false; } + + self.iter().all(|key| other.contains(key)) + } +} + +impl<T: Eq + Hash<S>, S, H: Hasher<S>> Eq for HashSet<T, H> {} + +impl<T: Eq + Hash<S> + fmt::Show, S, H: Hasher<S>> fmt::Show for HashSet<T, H> { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + try!(write!(f, "{{")); + + for (i, x) in self.iter().enumerate() { + if i != 0 { try!(write!(f, ", ")); } + try!(write!(f, "{}", *x)); + } + + write!(f, "}}") + } +} + +impl<T: Eq + Hash<S>, S, H: Hasher<S> + Default> FromIterator<T> for HashSet<T, H> { + fn from_iter<I: Iterator<T>>(iter: I) -> HashSet<T, H> { + let (lower, _) = iter.size_hint(); + let mut set = HashSet::with_capacity_and_hasher(lower, Default::default()); + set.extend(iter); + set + } +} + +impl<T: Eq + Hash<S>, S, H: Hasher<S> + Default> Extendable<T> for HashSet<T, H> { + fn extend<I: Iterator<T>>(&mut self, mut iter: I) { + for k in iter { + self.insert(k); + } + } +} + +impl<T: Eq + Hash<S>, S, H: Hasher<S> + Default> Default for HashSet<T, H> { + fn default() -> HashSet<T, H> { + HashSet::with_hasher(Default::default()) + } +} + +/// HashSet iterator +pub type SetItems<'a, K> = + iter::Map<'static, (&'a K, &'a ()), &'a K, Entries<'a, K, ()>>; + +/// HashSet move iterator +pub type SetMoveItems<K> = + iter::Map<'static, (K, ()), K, MoveEntries<K, ()>>; + +// `Repeat` is used to feed the filter closure an explicit capture +// of a reference to the other set +/// Set operations iterator +pub type SetAlgebraItems<'a, T, H> = + FilterMap<'static, (&'a HashSet<T, H>, &'a T), &'a T, + Zip<Repeat<&'a HashSet<T, H>>, SetItems<'a, T>>>; + +#[cfg(test)] +mod test_set { + use prelude::*; + + use super::HashSet; + use slice::ImmutablePartialEqSlice; + + #[test] + fn test_disjoint() { + let mut xs = HashSet::new(); + let mut ys = HashSet::new(); + assert!(xs.is_disjoint(&ys)); + assert!(ys.is_disjoint(&xs)); + assert!(xs.insert(5i)); + assert!(ys.insert(11i)); + assert!(xs.is_disjoint(&ys)); + assert!(ys.is_disjoint(&xs)); + assert!(xs.insert(7)); + assert!(xs.insert(19)); + assert!(xs.insert(4)); + assert!(ys.insert(2)); + assert!(ys.insert(-11)); + assert!(xs.is_disjoint(&ys)); + assert!(ys.is_disjoint(&xs)); + assert!(ys.insert(7)); + assert!(!xs.is_disjoint(&ys)); + assert!(!ys.is_disjoint(&xs)); + } + + #[test] + fn test_subset_and_superset() { + let mut a = HashSet::new(); + assert!(a.insert(0i)); + assert!(a.insert(5)); + assert!(a.insert(11)); + assert!(a.insert(7)); + + let mut b = HashSet::new(); + assert!(b.insert(0i)); + assert!(b.insert(7)); + assert!(b.insert(19)); + assert!(b.insert(250)); + assert!(b.insert(11)); + assert!(b.insert(200)); + + assert!(!a.is_subset(&b)); + assert!(!a.is_superset(&b)); + assert!(!b.is_subset(&a)); + assert!(!b.is_superset(&a)); + + assert!(b.insert(5)); + + assert!(a.is_subset(&b)); + assert!(!a.is_superset(&b)); + assert!(!b.is_subset(&a)); + assert!(b.is_superset(&a)); + } + + #[test] + fn test_iterate() { + let mut a = HashSet::new(); + for i in range(0u, 32) { + assert!(a.insert(i)); + } + let mut observed: u32 = 0; + for k in a.iter() { + observed |= 1 << *k; + } + assert_eq!(observed, 0xFFFF_FFFF); + } + + #[test] + fn test_intersection() { + let mut a = HashSet::new(); + let mut b = HashSet::new(); + + assert!(a.insert(11i)); + assert!(a.insert(1)); + assert!(a.insert(3)); + assert!(a.insert(77)); + assert!(a.insert(103)); + assert!(a.insert(5)); + assert!(a.insert(-5)); + + assert!(b.insert(2i)); + assert!(b.insert(11)); + assert!(b.insert(77)); + assert!(b.insert(-9)); + assert!(b.insert(-42)); + assert!(b.insert(5)); + assert!(b.insert(3)); + + let mut i = 0; + let expected = [3, 5, 11, 77]; + for x in a.intersection(&b) { + assert!(expected.contains(x)); + i += 1 + } + assert_eq!(i, expected.len()); + } + + #[test] + fn test_difference() { + let mut a = HashSet::new(); + let mut b = HashSet::new(); + + assert!(a.insert(1i)); + assert!(a.insert(3)); + assert!(a.insert(5)); + assert!(a.insert(9)); + assert!(a.insert(11)); + + assert!(b.insert(3i)); + assert!(b.insert(9)); + + let mut i = 0; + let expected = [1, 5, 11]; + for x in a.difference(&b) { + assert!(expected.contains(x)); + i += 1 + } + assert_eq!(i, expected.len()); + } + + #[test] + fn test_symmetric_difference() { + let mut a = HashSet::new(); + let mut b = HashSet::new(); + + assert!(a.insert(1i)); + assert!(a.insert(3)); + assert!(a.insert(5)); + assert!(a.insert(9)); + assert!(a.insert(11)); + + assert!(b.insert(-2i)); + assert!(b.insert(3)); + assert!(b.insert(9)); + assert!(b.insert(14)); + assert!(b.insert(22)); + + let mut i = 0; + let expected = [-2, 1, 5, 11, 14, 22]; + for x in a.symmetric_difference(&b) { + assert!(expected.contains(x)); + i += 1 + } + assert_eq!(i, expected.len()); + } + + #[test] + fn test_union() { + let mut a = HashSet::new(); + let mut b = HashSet::new(); + + assert!(a.insert(1i)); + assert!(a.insert(3)); + assert!(a.insert(5)); + assert!(a.insert(9)); + assert!(a.insert(11)); + assert!(a.insert(16)); + assert!(a.insert(19)); + assert!(a.insert(24)); + + assert!(b.insert(-2i)); + assert!(b.insert(1)); + assert!(b.insert(5)); + assert!(b.insert(9)); + assert!(b.insert(13)); + assert!(b.insert(19)); + + let mut i = 0; + let expected = [-2, 1, 3, 5, 9, 11, 13, 16, 19, 24]; + for x in a.union(&b) { + assert!(expected.contains(x)); + i += 1 + } + assert_eq!(i, expected.len()); + } + + #[test] + fn test_from_iter() { + let xs = [1i, 2, 3, 4, 5, 6, 7, 8, 9]; + + let set: HashSet<int> = xs.iter().map(|&x| x).collect(); + + for x in xs.iter() { + assert!(set.contains(x)); + } + } + + #[test] + fn test_move_iter() { + let hs = { + let mut hs = HashSet::new(); + + hs.insert('a'); + hs.insert('b'); + + hs + }; + + let v = hs.into_iter().collect::<Vec<char>>(); + assert!(['a', 'b'] == v.as_slice() || ['b', 'a'] == v.as_slice()); + } + + #[test] + fn test_eq() { + // These constants once happened to expose a bug in insert(). + // I'm keeping them around to prevent a regression. + let mut s1 = HashSet::new(); + + s1.insert(1i); + s1.insert(2); + s1.insert(3); + + let mut s2 = HashSet::new(); + + s2.insert(1i); + s2.insert(2); + + assert!(s1 != s2); + + s2.insert(3); + + assert_eq!(s1, s2); + } + + #[test] + fn test_show() { + let mut set: HashSet<int> = HashSet::new(); + let empty: HashSet<int> = HashSet::new(); + + set.insert(1i); + set.insert(2); + + let set_str = format!("{}", set); + + assert!(set_str == "{1, 2}".to_string() || set_str == "{2, 1}".to_string()); + assert_eq!(format!("{}", empty), "{}".to_string()); + } +} diff --git a/src/libstd/collections/hash/table.rs b/src/libstd/collections/hash/table.rs new file mode 100644 index 00000000000..4d73029b7b0 --- /dev/null +++ b/src/libstd/collections/hash/table.rs @@ -0,0 +1,907 @@ +// Copyright 2014 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or +// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license +// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. +// +// ignore-lexer-test FIXME #15883 + +use clone::Clone; +use cmp; +use hash::{Hash, Hasher}; +use iter::{Iterator, count}; +use kinds::{Sized, marker}; +use mem::{min_align_of, size_of}; +use mem; +use num::{CheckedAdd, CheckedMul, is_power_of_two}; +use ops::{Deref, DerefMut, Drop}; +use option::{Some, None, Option}; +use ptr::{RawPtr, copy_nonoverlapping_memory, zero_memory}; +use ptr; +use rt::heap::{allocate, deallocate}; + +const EMPTY_BUCKET: u64 = 0u64; + +/// The raw hashtable, providing safe-ish access to the unzipped and highly +/// optimized arrays of hashes, keys, and values. +/// +/// This design uses less memory and is a lot faster than the naive +/// `Vec<Option<u64, K, V>>`, because we don't pay for the overhead of an +/// option on every element, and we get a generally more cache-aware design. +/// +/// Essential invariants of this structure: +/// +/// - if t.hashes[i] == EMPTY_BUCKET, then `Bucket::at_index(&t, i).raw` +/// points to 'undefined' contents. Don't read from it. This invariant is +/// enforced outside this module with the `EmptyBucket`, `FullBucket`, +/// and `SafeHash` types. +/// +/// - An `EmptyBucket` is only constructed at an index with +/// a hash of EMPTY_BUCKET. +/// +/// - A `FullBucket` is only constructed at an index with a +/// non-EMPTY_BUCKET hash. +/// +/// - A `SafeHash` is only constructed for non-`EMPTY_BUCKET` hash. We get +/// around hashes of zero by changing them to 0x8000_0000_0000_0000, +/// which will likely map to the same bucket, while not being confused +/// with "empty". +/// +/// - All three "arrays represented by pointers" are the same length: +/// `capacity`. This is set at creation and never changes. The arrays +/// are unzipped to save space (we don't have to pay for the padding +/// between odd sized elements, such as in a map from u64 to u8), and +/// be more cache aware (scanning through 8 hashes brings in at most +/// 2 cache lines, since they're all right beside each other). +/// +/// You can kind of think of this module/data structure as a safe wrapper +/// around just the "table" part of the hashtable. It enforces some +/// invariants at the type level and employs some performance trickery, +/// but in general is just a tricked out `Vec<Option<u64, K, V>>`. +#[unsafe_no_drop_flag] +pub struct RawTable<K, V> { + capacity: uint, + size: uint, + hashes: *mut u64, + // Because K/V do not appear directly in any of the types in the struct, + // inform rustc that in fact instances of K and V are reachable from here. + marker: marker::CovariantType<(K,V)>, +} + +struct RawBucket<K, V> { + hash: *mut u64, + key: *mut K, + val: *mut V +} + +pub struct Bucket<K, V, M> { + raw: RawBucket<K, V>, + idx: uint, + table: M +} + +pub struct EmptyBucket<K, V, M> { + raw: RawBucket<K, V>, + idx: uint, + table: M +} + +pub struct FullBucket<K, V, M> { + raw: RawBucket<K, V>, + idx: uint, + table: M +} + +pub type EmptyBucketImm<'table, K, V> = EmptyBucket<K, V, &'table RawTable<K, V>>; +pub type FullBucketImm<'table, K, V> = FullBucket<K, V, &'table RawTable<K, V>>; + +pub type EmptyBucketMut<'table, K, V> = EmptyBucket<K, V, &'table mut RawTable<K, V>>; +pub type FullBucketMut<'table, K, V> = FullBucket<K, V, &'table mut RawTable<K, V>>; + +pub enum BucketState<K, V, M> { + Empty(EmptyBucket<K, V, M>), + Full(FullBucket<K, V, M>), +} + +// A GapThenFull encapsulates the state of two consecutive buckets at once. +// The first bucket, called the gap, is known to be empty. +// The second bucket is full. +struct GapThenFull<K, V, M> { + gap: EmptyBucket<K, V, ()>, + full: FullBucket<K, V, M>, +} + +/// A hash that is not zero, since we use a hash of zero to represent empty +/// buckets. +#[deriving(PartialEq)] +pub struct SafeHash { + hash: u64, +} + +impl SafeHash { + /// Peek at the hash value, which is guaranteed to be non-zero. + #[inline(always)] + pub fn inspect(&self) -> u64 { self.hash } +} + +/// We need to remove hashes of 0. That's reserved for empty buckets. +/// This function wraps up `hash_keyed` to be the only way outside this +/// module to generate a SafeHash. +pub fn make_hash<Sized? T: Hash<S>, S, H: Hasher<S>>(hasher: &H, t: &T) -> SafeHash { + match hasher.hash(t) { + // This constant is exceedingly likely to hash to the same + // bucket, but it won't be counted as empty! Just so we can maintain + // our precious uniform distribution of initial indexes. + EMPTY_BUCKET => SafeHash { hash: 0x8000_0000_0000_0000 }, + h => SafeHash { hash: h }, + } +} + +// `replace` casts a `*u64` to a `*SafeHash`. Since we statically +// ensure that a `FullBucket` points to an index with a non-zero hash, +// and a `SafeHash` is just a `u64` with a different name, this is +// safe. +// +// This test ensures that a `SafeHash` really IS the same size as a +// `u64`. If you need to change the size of `SafeHash` (and +// consequently made this test fail), `replace` needs to be +// modified to no longer assume this. +#[test] +fn can_alias_safehash_as_u64() { + assert_eq!(size_of::<SafeHash>(), size_of::<u64>()) +} + +impl<K, V> RawBucket<K, V> { + unsafe fn offset(self, count: int) -> RawBucket<K, V> { + RawBucket { + hash: self.hash.offset(count), + key: self.key.offset(count), + val: self.val.offset(count), + } + } +} + +// For parameterizing over mutability. +impl<'t, K, V> Deref<RawTable<K, V>> for &'t RawTable<K, V> { + fn deref(&self) -> &RawTable<K, V> { + &**self + } +} + +impl<'t, K, V> Deref<RawTable<K, V>> for &'t mut RawTable<K, V> { + fn deref(&self) -> &RawTable<K,V> { + &**self + } +} + +impl<'t, K, V> DerefMut<RawTable<K, V>> for &'t mut RawTable<K, V> { + fn deref_mut(&mut self) -> &mut RawTable<K,V> { + &mut **self + } +} + +// Buckets hold references to the table. +impl<K, V, M> FullBucket<K, V, M> { + /// Borrow a reference to the table. + pub fn table(&self) -> &M { + &self.table + } + /// Move out the reference to the table. + pub fn into_table(self) -> M { + self.table + } + /// Get the raw index. + pub fn index(&self) -> uint { + self.idx + } +} + +impl<K, V, M> EmptyBucket<K, V, M> { + /// Borrow a reference to the table. + pub fn table(&self) -> &M { + &self.table + } + /// Move out the reference to the table. + pub fn into_table(self) -> M { + self.table + } +} + +impl<K, V, M> Bucket<K, V, M> { + /// Move out the reference to the table. + pub fn into_table(self) -> M { + self.table + } + /// Get the raw index. + pub fn index(&self) -> uint { + self.idx + } +} + +impl<K, V, M: Deref<RawTable<K, V>>> Bucket<K, V, M> { + pub fn new(table: M, hash: &SafeHash) -> Bucket<K, V, M> { + Bucket::at_index(table, hash.inspect() as uint) + } + + pub fn at_index(table: M, ib_index: uint) -> Bucket<K, V, M> { + let ib_index = ib_index & (table.capacity() - 1); + Bucket { + raw: unsafe { + table.first_bucket_raw().offset(ib_index as int) + }, + idx: ib_index, + table: table + } + } + + pub fn first(table: M) -> Bucket<K, V, M> { + Bucket { + raw: table.first_bucket_raw(), + idx: 0, + table: table + } + } + + /// Reads a bucket at a given index, returning an enum indicating whether + /// it's initialized or not. You need to match on this enum to get + /// the appropriate types to call most of the other functions in + /// this module. + pub fn peek(self) -> BucketState<K, V, M> { + match unsafe { *self.raw.hash } { + EMPTY_BUCKET => + Empty(EmptyBucket { + raw: self.raw, + idx: self.idx, + table: self.table + }), + _ => + Full(FullBucket { + raw: self.raw, + idx: self.idx, + table: self.table + }) + } + } + + /// Modifies the bucket pointer in place to make it point to the next slot. + pub fn next(&mut self) { + // Branchless bucket iteration step. + // As we reach the end of the table... + // We take the current idx: 0111111b + // Xor it by its increment: ^ 1000000b + // ------------ + // 1111111b + // Then AND with the capacity: & 1000000b + // ------------ + // to get the backwards offset: 1000000b + // ... and it's zero at all other times. + let maybe_wraparound_dist = (self.idx ^ (self.idx + 1)) & self.table.capacity(); + // Finally, we obtain the offset 1 or the offset -cap + 1. + let dist = 1i - (maybe_wraparound_dist as int); + + self.idx += 1; + + unsafe { + self.raw = self.raw.offset(dist); + } + } +} + +impl<K, V, M: Deref<RawTable<K, V>>> EmptyBucket<K, V, M> { + #[inline] + pub fn next(self) -> Bucket<K, V, M> { + let mut bucket = self.into_bucket(); + bucket.next(); + bucket + } + + #[inline] + pub fn into_bucket(self) -> Bucket<K, V, M> { + Bucket { + raw: self.raw, + idx: self.idx, + table: self.table + } + } + + pub fn gap_peek(self) -> Option<GapThenFull<K, V, M>> { + let gap = EmptyBucket { + raw: self.raw, + idx: self.idx, + table: () + }; + + match self.next().peek() { + Full(bucket) => { + Some(GapThenFull { + gap: gap, + full: bucket + }) + } + Empty(..) => None + } + } +} + +impl<K, V, M: DerefMut<RawTable<K, V>>> EmptyBucket<K, V, M> { + /// Puts given key and value pair, along with the key's hash, + /// into this bucket in the hashtable. Note how `self` is 'moved' into + /// this function, because this slot will no longer be empty when + /// we return! A `FullBucket` is returned for later use, pointing to + /// the newly-filled slot in the hashtable. + /// + /// Use `make_hash` to construct a `SafeHash` to pass to this function. + pub fn put(mut self, hash: SafeHash, key: K, value: V) + -> FullBucket<K, V, M> { + unsafe { + *self.raw.hash = hash.inspect(); + ptr::write(self.raw.key, key); + ptr::write(self.raw.val, value); + } + + self.table.size += 1; + + FullBucket { raw: self.raw, idx: self.idx, table: self.table } + } +} + +impl<K, V, M: Deref<RawTable<K, V>>> FullBucket<K, V, M> { + #[inline] + pub fn next(self) -> Bucket<K, V, M> { + let mut bucket = self.into_bucket(); + bucket.next(); + bucket + } + + #[inline] + pub fn into_bucket(self) -> Bucket<K, V, M> { + Bucket { + raw: self.raw, + idx: self.idx, + table: self.table + } + } + + /// Get the distance between this bucket and the 'ideal' location + /// as determined by the key's hash stored in it. + /// + /// In the cited blog posts above, this is called the "distance to + /// initial bucket", or DIB. Also known as "probe count". + pub fn distance(&self) -> uint { + // Calculates the distance one has to travel when going from + // `hash mod capacity` onwards to `idx mod capacity`, wrapping around + // if the destination is not reached before the end of the table. + (self.idx - self.hash().inspect() as uint) & (self.table.capacity() - 1) + } + + #[inline] + pub fn hash(&self) -> SafeHash { + unsafe { + SafeHash { + hash: *self.raw.hash + } + } + } + + /// Gets references to the key and value at a given index. + pub fn read(&self) -> (&K, &V) { + unsafe { + (&*self.raw.key, + &*self.raw.val) + } + } +} + +impl<K, V, M: DerefMut<RawTable<K, V>>> FullBucket<K, V, M> { + /// Removes this bucket's key and value from the hashtable. + /// + /// This works similarly to `put`, building an `EmptyBucket` out of the + /// taken bucket. + pub fn take(mut self) -> (EmptyBucket<K, V, M>, K, V) { + let key = self.raw.key as *const K; + let val = self.raw.val as *const V; + + self.table.size -= 1; + + unsafe { + *self.raw.hash = EMPTY_BUCKET; + ( + EmptyBucket { + raw: self.raw, + idx: self.idx, + table: self.table + }, + ptr::read(key), + ptr::read(val) + ) + } + } + + pub fn replace(&mut self, h: SafeHash, k: K, v: V) -> (SafeHash, K, V) { + unsafe { + let old_hash = ptr::replace(self.raw.hash as *mut SafeHash, h); + let old_key = ptr::replace(self.raw.key, k); + let old_val = ptr::replace(self.raw.val, v); + + (old_hash, old_key, old_val) + } + } + + /// Gets mutable references to the key and value at a given index. + pub fn read_mut(&mut self) -> (&mut K, &mut V) { + unsafe { + (&mut *self.raw.key, + &mut *self.raw.val) + } + } +} + +impl<'t, K, V, M: Deref<RawTable<K, V>> + 't> FullBucket<K, V, M> { + /// Exchange a bucket state for immutable references into the table. + /// Because the underlying reference to the table is also consumed, + /// no further changes to the structure of the table are possible; + /// in exchange for this, the returned references have a longer lifetime + /// than the references returned by `read()`. + pub fn into_refs(self) -> (&'t K, &'t V) { + unsafe { + (&*self.raw.key, + &*self.raw.val) + } + } +} + +impl<'t, K, V, M: DerefMut<RawTable<K, V>> + 't> FullBucket<K, V, M> { + /// This works similarly to `into_refs`, exchanging a bucket state + /// for mutable references into the table. + pub fn into_mut_refs(self) -> (&'t mut K, &'t mut V) { + unsafe { + (&mut *self.raw.key, + &mut *self.raw.val) + } + } +} + +impl<K, V, M> BucketState<K, V, M> { + // For convenience. + pub fn expect_full(self) -> FullBucket<K, V, M> { + match self { + Full(full) => full, + Empty(..) => panic!("Expected full bucket") + } + } +} + +impl<K, V, M: Deref<RawTable<K, V>>> GapThenFull<K, V, M> { + #[inline] + pub fn full(&self) -> &FullBucket<K, V, M> { + &self.full + } + + pub fn shift(mut self) -> Option<GapThenFull<K, V, M>> { + unsafe { + *self.gap.raw.hash = mem::replace(&mut *self.full.raw.hash, EMPTY_BUCKET); + copy_nonoverlapping_memory(self.gap.raw.key, self.full.raw.key as *const K, 1); + copy_nonoverlapping_memory(self.gap.raw.val, self.full.raw.val as *const V, 1); + } + + let FullBucket { raw: prev_raw, idx: prev_idx, .. } = self.full; + + match self.full.next().peek() { + Full(bucket) => { + self.gap.raw = prev_raw; + self.gap.idx = prev_idx; + + self.full = bucket; + + Some(self) + } + Empty(..) => None + } + } +} + + +/// Rounds up to a multiple of a power of two. Returns the closest multiple +/// of `target_alignment` that is higher or equal to `unrounded`. +/// +/// # Failure +/// +/// Fails if `target_alignment` is not a power of two. +fn round_up_to_next(unrounded: uint, target_alignment: uint) -> uint { + assert!(is_power_of_two(target_alignment)); + (unrounded + target_alignment - 1) & !(target_alignment - 1) +} + +#[test] +fn test_rounding() { + assert_eq!(round_up_to_next(0, 4), 0); + assert_eq!(round_up_to_next(1, 4), 4); + assert_eq!(round_up_to_next(2, 4), 4); + assert_eq!(round_up_to_next(3, 4), 4); + assert_eq!(round_up_to_next(4, 4), 4); + assert_eq!(round_up_to_next(5, 4), 8); +} + +// Returns a tuple of (key_offset, val_offset), +// from the start of a mallocated array. +fn calculate_offsets(hashes_size: uint, + keys_size: uint, keys_align: uint, + vals_align: uint) + -> (uint, uint) { + let keys_offset = round_up_to_next(hashes_size, keys_align); + let end_of_keys = keys_offset + keys_size; + + let vals_offset = round_up_to_next(end_of_keys, vals_align); + + (keys_offset, vals_offset) +} + +// Returns a tuple of (minimum required malloc alignment, hash_offset, +// array_size), from the start of a mallocated array. +fn calculate_allocation(hash_size: uint, hash_align: uint, + keys_size: uint, keys_align: uint, + vals_size: uint, vals_align: uint) + -> (uint, uint, uint) { + let hash_offset = 0; + let (_, vals_offset) = calculate_offsets(hash_size, + keys_size, keys_align, + vals_align); + let end_of_vals = vals_offset + vals_size; + + let min_align = cmp::max(hash_align, cmp::max(keys_align, vals_align)); + + (min_align, hash_offset, end_of_vals) +} + +#[test] +fn test_offset_calculation() { + assert_eq!(calculate_allocation(128, 8, 15, 1, 4, 4), (8, 0, 148)); + assert_eq!(calculate_allocation(3, 1, 2, 1, 1, 1), (1, 0, 6)); + assert_eq!(calculate_allocation(6, 2, 12, 4, 24, 8), (8, 0, 48)); + assert_eq!(calculate_offsets(128, 15, 1, 4), (128, 144)); + assert_eq!(calculate_offsets(3, 2, 1, 1), (3, 5)); + assert_eq!(calculate_offsets(6, 12, 4, 8), (8, 24)); +} + +impl<K, V> RawTable<K, V> { + /// Does not initialize the buckets. The caller should ensure they, + /// at the very least, set every hash to EMPTY_BUCKET. + unsafe fn new_uninitialized(capacity: uint) -> RawTable<K, V> { + if capacity == 0 { + return RawTable { + size: 0, + capacity: 0, + hashes: 0 as *mut u64, + marker: marker::CovariantType, + }; + } + // No need for `checked_mul` before a more restrictive check performed + // later in this method. + let hashes_size = capacity * size_of::<u64>(); + let keys_size = capacity * size_of::< K >(); + let vals_size = capacity * size_of::< V >(); + + // Allocating hashmaps is a little tricky. We need to allocate three + // arrays, but since we know their sizes and alignments up front, + // we just allocate a single array, and then have the subarrays + // point into it. + // + // This is great in theory, but in practice getting the alignment + // right is a little subtle. Therefore, calculating offsets has been + // factored out into a different function. + let (malloc_alignment, hash_offset, size) = + calculate_allocation( + hashes_size, min_align_of::<u64>(), + keys_size, min_align_of::< K >(), + vals_size, min_align_of::< V >()); + + // One check for overflow that covers calculation and rounding of size. + let size_of_bucket = size_of::<u64>().checked_add(&size_of::<K>()).unwrap() + .checked_add(&size_of::<V>()).unwrap(); + assert!(size >= capacity.checked_mul(&size_of_bucket) + .expect("capacity overflow"), + "capacity overflow"); + + let buffer = allocate(size, malloc_alignment); + if buffer.is_null() { ::alloc::oom() } + + let hashes = buffer.offset(hash_offset as int) as *mut u64; + + RawTable { + capacity: capacity, + size: 0, + hashes: hashes, + marker: marker::CovariantType, + } + } + + fn first_bucket_raw(&self) -> RawBucket<K, V> { + let hashes_size = self.capacity * size_of::<u64>(); + let keys_size = self.capacity * size_of::<K>(); + + let buffer = self.hashes as *mut u8; + let (keys_offset, vals_offset) = calculate_offsets(hashes_size, + keys_size, min_align_of::<K>(), + min_align_of::<V>()); + + unsafe { + RawBucket { + hash: self.hashes, + key: buffer.offset(keys_offset as int) as *mut K, + val: buffer.offset(vals_offset as int) as *mut V + } + } + } + + /// Creates a new raw table from a given capacity. All buckets are + /// initially empty. + #[allow(experimental)] + pub fn new(capacity: uint) -> RawTable<K, V> { + unsafe { + let ret = RawTable::new_uninitialized(capacity); + zero_memory(ret.hashes, capacity); + ret + } + } + + /// The hashtable's capacity, similar to a vector's. + pub fn capacity(&self) -> uint { + self.capacity + } + + /// The number of elements ever `put` in the hashtable, minus the number + /// of elements ever `take`n. + pub fn size(&self) -> uint { + self.size + } + + fn raw_buckets(&self) -> RawBuckets<K, V> { + RawBuckets { + raw: self.first_bucket_raw(), + hashes_end: unsafe { + self.hashes.offset(self.capacity as int) + }, + marker: marker::ContravariantLifetime, + } + } + + pub fn iter(&self) -> Entries<K, V> { + Entries { + iter: self.raw_buckets(), + elems_left: self.size(), + } + } + + pub fn iter_mut(&mut self) -> MutEntries<K, V> { + MutEntries { + iter: self.raw_buckets(), + elems_left: self.size(), + } + } + + pub fn into_iter(self) -> MoveEntries<K, V> { + let RawBuckets { raw, hashes_end, .. } = self.raw_buckets(); + // Replace the marker regardless of lifetime bounds on parameters. + MoveEntries { + iter: RawBuckets { + raw: raw, + hashes_end: hashes_end, + marker: marker::ContravariantLifetime, + }, + table: self, + } + } + + /// Returns an iterator that copies out each entry. Used while the table + /// is being dropped. + unsafe fn rev_move_buckets(&mut self) -> RevMoveBuckets<K, V> { + let raw_bucket = self.first_bucket_raw(); + RevMoveBuckets { + raw: raw_bucket.offset(self.capacity as int), + hashes_end: raw_bucket.hash, + elems_left: self.size, + marker: marker::ContravariantLifetime, + } + } +} + +/// A raw iterator. The basis for some other iterators in this module. Although +/// this interface is safe, it's not used outside this module. +struct RawBuckets<'a, K, V> { + raw: RawBucket<K, V>, + hashes_end: *mut u64, + marker: marker::ContravariantLifetime<'a>, +} + +impl<'a, K, V> Iterator<RawBucket<K, V>> for RawBuckets<'a, K, V> { + fn next(&mut self) -> Option<RawBucket<K, V>> { + while self.raw.hash != self.hashes_end { + unsafe { + // We are swapping out the pointer to a bucket and replacing + // it with the pointer to the next one. + let prev = ptr::replace(&mut self.raw, self.raw.offset(1)); + if *prev.hash != EMPTY_BUCKET { + return Some(prev); + } + } + } + + None + } +} + +/// An iterator that moves out buckets in reverse order. It leaves the table +/// in an an inconsistent state and should only be used for dropping +/// the table's remaining entries. It's used in the implementation of Drop. +struct RevMoveBuckets<'a, K, V> { + raw: RawBucket<K, V>, + hashes_end: *mut u64, + elems_left: uint, + marker: marker::ContravariantLifetime<'a>, +} + +impl<'a, K, V> Iterator<(K, V)> for RevMoveBuckets<'a, K, V> { + fn next(&mut self) -> Option<(K, V)> { + if self.elems_left == 0 { + return None; + } + + loop { + debug_assert!(self.raw.hash != self.hashes_end); + + unsafe { + self.raw = self.raw.offset(-1); + + if *self.raw.hash != EMPTY_BUCKET { + self.elems_left -= 1; + return Some(( + ptr::read(self.raw.key as *const K), + ptr::read(self.raw.val as *const V) + )); + } + } + } + } +} + +/// Iterator over shared references to entries in a table. +pub struct Entries<'a, K: 'a, V: 'a> { + iter: RawBuckets<'a, K, V>, + elems_left: uint, +} + +/// Iterator over mutable references to entries in a table. +pub struct MutEntries<'a, K: 'a, V: 'a> { + iter: RawBuckets<'a, K, V>, + elems_left: uint, +} + +/// Iterator over the entries in a table, consuming the table. +pub struct MoveEntries<K, V> { + table: RawTable<K, V>, + iter: RawBuckets<'static, K, V> +} + +impl<'a, K, V> Iterator<(&'a K, &'a V)> for Entries<'a, K, V> { + fn next(&mut self) -> Option<(&'a K, &'a V)> { + self.iter.next().map(|bucket| { + self.elems_left -= 1; + unsafe { + (&*bucket.key, + &*bucket.val) + } + }) + } + + fn size_hint(&self) -> (uint, Option<uint>) { + (self.elems_left, Some(self.elems_left)) + } +} + +impl<'a, K, V> Iterator<(&'a K, &'a mut V)> for MutEntries<'a, K, V> { + fn next(&mut self) -> Option<(&'a K, &'a mut V)> { + self.iter.next().map(|bucket| { + self.elems_left -= 1; + unsafe { + (&*bucket.key, + &mut *bucket.val) + } + }) + } + + fn size_hint(&self) -> (uint, Option<uint>) { + (self.elems_left, Some(self.elems_left)) + } +} + +impl<K, V> Iterator<(SafeHash, K, V)> for MoveEntries<K, V> { + fn next(&mut self) -> Option<(SafeHash, K, V)> { + self.iter.next().map(|bucket| { + self.table.size -= 1; + unsafe { + ( + SafeHash { + hash: *bucket.hash, + }, + ptr::read(bucket.key as *const K), + ptr::read(bucket.val as *const V) + ) + } + }) + } + + fn size_hint(&self) -> (uint, Option<uint>) { + let size = self.table.size(); + (size, Some(size)) + } +} + +impl<K: Clone, V: Clone> Clone for RawTable<K, V> { + fn clone(&self) -> RawTable<K, V> { + unsafe { + let mut new_ht = RawTable::new_uninitialized(self.capacity()); + + { + let cap = self.capacity(); + let mut new_buckets = Bucket::first(&mut new_ht); + let mut buckets = Bucket::first(self); + while buckets.index() != cap { + match buckets.peek() { + Full(full) => { + let (h, k, v) = { + let (k, v) = full.read(); + (full.hash(), k.clone(), v.clone()) + }; + *new_buckets.raw.hash = h.inspect(); + ptr::write(new_buckets.raw.key, k); + ptr::write(new_buckets.raw.val, v); + } + Empty(..) => { + *new_buckets.raw.hash = EMPTY_BUCKET; + } + } + new_buckets.next(); + buckets.next(); + } + }; + + new_ht.size = self.size(); + + new_ht + } + } +} + +#[unsafe_destructor] +impl<K, V> Drop for RawTable<K, V> { + fn drop(&mut self) { + if self.hashes.is_null() { + return; + } + // This is done in reverse because we've likely partially taken + // some elements out with `.into_iter()` from the front. + // Check if the size is 0, so we don't do a useless scan when + // dropping empty tables such as on resize. + // Also avoid double drop of elements that have been already moved out. + unsafe { + for _ in self.rev_move_buckets() {} + } + + let hashes_size = self.capacity * size_of::<u64>(); + let keys_size = self.capacity * size_of::<K>(); + let vals_size = self.capacity * size_of::<V>(); + let (align, _, size) = calculate_allocation(hashes_size, min_align_of::<u64>(), + keys_size, min_align_of::<K>(), + vals_size, min_align_of::<V>()); + + unsafe { + deallocate(self.hashes as *mut u8, size, align); + // Remember how everything was allocated out of one buffer + // during initialization? We only need one call to free here. + } + } +} |