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Diffstat (limited to 'src/libstd/collections/hashmap/table.rs')
| -rw-r--r-- | src/libstd/collections/hashmap/table.rs | 877 |
1 files changed, 877 insertions, 0 deletions
diff --git a/src/libstd/collections/hashmap/table.rs b/src/libstd/collections/hashmap/table.rs new file mode 100644 index 00000000000..96d1a9ba2fb --- /dev/null +++ b/src/libstd/collections/hashmap/table.rs @@ -0,0 +1,877 @@ +// 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 mem::{min_align_of, size_of}; +use mem; +use num::{CheckedMul, is_power_of_two}; +use ops::{Deref, DerefMut, Drop}; +use option::{Some, None, Option}; +use ptr::RawPtr; +use ptr::set_memory; +use ptr::write; +use ptr; +use rt::heap::{allocate, deallocate}; + +static 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. +/// +/// Key invariants of this structure: +/// +/// - if hashes[i] == EMPTY_BUCKET, then keys[i] and vals[i] have +/// 'undefined' contents. Don't read from them. This invariant is +/// enforced outside this module with the `EmptyIndex`, `FullIndex`, +/// and `SafeHash` types. +/// +/// - An `EmptyIndex` is only constructed for a bucket at an index with +/// a hash of EMPTY_BUCKET. +/// +/// - A `FullIndex` is only constructed for a bucket 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 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>>`. +/// +/// FIXME(cgaebel): +/// +/// Feb 11, 2014: This hashtable was just implemented, and, hard as I tried, +/// isn't yet totally safe. There's a "known exploit" that you can create +/// multiple FullIndexes for a bucket, `take` one, and then still `take` +/// the other causing undefined behavior. Currently, there's no story +/// for how to protect against this statically. Therefore, there are asserts +/// on `take`, `get`, `get_mut`, and `put` which check the bucket state. +/// With time, and when we're confident this works correctly, they should +/// be removed. Also, the bounds check in `peek` is especially painful, +/// as that's called in the innermost loops of the hashtable and has the +/// potential to be a major performance drain. Remove this too. +/// +/// Or, better than remove, only enable these checks for debug builds. +/// There's currently no "debug-only" asserts in rust, so if you're reading +/// this and going "what? of course there are debug-only asserts!", then +/// please make this use them! +#[unsafe_no_drop_flag] +pub struct RawTable<K, V> { + capacity: uint, + size: uint, + hashes: *mut u64 +} + +/// A bucket that holds a reference to the table +pub trait BucketWithTable<M> { + /// A bucket that holds a reference to the table + fn table<'a>(&'a self) -> &'a M; + + /// Move out the reference to the table. + fn into_table(self) -> M; + + /// Get the raw index. + fn index(&self) -> uint; +} + +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>>; + +struct GapThenFull<K, V, M> { + gap: EmptyBucket<K, V, ()>, + full: FullBucket<K, V, M> +} + +impl<K, V, M: Deref<RawTable<K,V>>> GapThenFull<K, V, M> { + pub fn full<'a>(&'a self) -> &'a 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); + mem::overwrite(self.gap.raw.key, ptr::read(self.full.raw.key as *const K)); + mem::overwrite(self.gap.raw.val, ptr::read(self.full.raw.val as *const V)); + } + + let FullBucket { raw, idx, .. } = self.full; + + match self.full.next().peek() { + Empty(_) => None, + Full(bucket) => { + self.gap.raw = raw; + self.gap.idx = idx; + + self.full = bucket; + self.full.idx &= self.full.table.capacity - 1; + + Some(self) + } + } + } +} + +impl<K, V> RawPtr<u64> for 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), + } + } + + fn null() -> RawBucket<K, V> { + RawBucket { + hash: RawPtr::null(), + key: RawPtr::null(), + val: RawPtr::null() + } + } + + fn is_null(&self) -> bool { + self.hash.is_null() + } + + fn to_uint(&self) -> uint { + self.hash.to_uint() + } + + unsafe fn to_option(&self) -> Option<&u64> { + self.hash.to_option() + } +} + +impl<K, V, M: Deref<RawTable<K,V>>> EmptyBucket<K, V, M> { + pub fn next(self) -> Bucket<K, V, M> { + let mut bucket = self.into_bucket(); + bucket.next(); + bucket + } + + 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() { + Empty(_) => None, + Full(bucket) => { + Some(GapThenFull { + gap: gap, + full: bucket + }) + } + } + } +} + +impl<K, V, M: DerefMut<RawTable<K,V>>> EmptyBucket<K, V, M> { + pub fn put(mut self, hash: SafeHash, key: K, value: V) + -> FullBucket<K, V, M> { + unsafe { + *self.raw.hash = hash.inspect(); + write(self.raw.key, key); + 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> { + pub fn next(self) -> Bucket<K, V, M> { + let mut bucket = self.into_bucket(); + bucket.next(); + bucket + } + + pub fn into_bucket(self) -> Bucket<K, V, M> { + Bucket { + raw: self.raw, + idx: self.idx, + table: self.table + } + } + + pub fn distance(&self) -> uint { + (self.idx - self.hash().inspect() as uint) & (self.table.capacity() - 1) + } + + pub fn hash(&self) -> SafeHash { + unsafe { + SafeHash { + hash: *self.raw.hash + } + } + } + + pub fn read<'a>(&'a self) -> (&'a K, &'a V) { + unsafe { + (&*self.raw.key, + &*self.raw.val) + } + } + + pub fn into_refs(self) -> (&K, &V) { + unsafe { + // debug_assert!(*self.raw.hash != EMPTY_BUCKET); + (&*self.raw.key, + &*self.raw.val) + } + } +} + +impl<K, V, M: DerefMut<RawTable<K,V>>> FullBucket<K, V, M> { + 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) + } + } + + pub fn read_mut<'a>(&'a self) -> (&'a mut K, &'a mut V) { + unsafe { + // debug_assert!(*self.raw.hash != EMPTY_BUCKET); + (&mut *self.raw.key, + &mut *self.raw.val) + } + } + + pub fn into_mut_refs(self) -> (&mut K, &mut V) { + unsafe { + // debug_assert!(*self.raw.hash != EMPTY_BUCKET); + (&mut *self.raw.key, + &mut *self.raw.val) + } + } +} + +impl<K, V, M: Deref<RawTable<K,V>>> Bucket<K, V, M> { + pub fn new(table: M, hash: &SafeHash) -> Bucket<K, V, M> { + let ib_index = (hash.inspect() as uint) & (table.capacity() - 1); + Bucket { + raw: unsafe { + table.as_mut_ptrs().offset(ib_index as int) + }, + idx: ib_index, + table: table + } + } + + 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.as_mut_ptrs().offset(ib_index as int) + }, + idx: ib_index, + table: table + } + } + + pub fn first(table: M) -> Bucket<K, V, M> { + Bucket { + raw: table.as_mut_ptrs(), + idx: 0, + table: table + } + } + + 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 + }) + } + } + + pub fn next(&mut self) { + self.idx += 1; + + let dist = if self.idx == self.table.capacity() { + -(self.table.capacity() as int - 1) + } else { + 1i + }; + + unsafe { + self.raw = self.raw.offset(dist); + } + } +} + +impl<K, V, M> BucketWithTable<M> for FullBucket<K, V, M> { + fn table<'a>(&'a self) -> &'a M { + &self.table + } + + fn into_table(self) -> M { + self.table + } + + fn index(&self) -> uint { + self.idx + } +} + +impl<K, V, M> BucketWithTable<M> for EmptyBucket<K, V, M> { + fn table<'a>(&'a self) -> &'a M { + &self.table + } + + fn into_table(self) -> M { + self.table + } + + fn index(&self) -> uint { + self.idx + } +} + +impl<K, V, M> BucketWithTable<M> for Bucket<K, V, M> { + fn table<'a>(&'a self) -> &'a M { + &self.table + } + + fn into_table(self) -> M { + self.table + } + + fn index(&self) -> uint { + self.idx + } +} + +impl<'table,K,V> Deref<RawTable<K,V>> for &'table RawTable<K,V> { + fn deref<'a>(&'a self) -> &'a RawTable<K,V> { + &**self + } +} + +impl<'table,K,V> Deref<RawTable<K,V>> for &'table mut RawTable<K,V> { + fn deref<'a>(&'a self) -> &'a RawTable<K,V> { + &**self + } +} + +impl<'table,K,V> DerefMut<RawTable<K,V>> for &'table mut RawTable<K,V> { + fn deref_mut<'a>(&'a mut self) -> &'a mut RawTable<K,V> { + &mut **self + } +} + +pub enum BucketState<K, V, M> { + Empty(EmptyBucket<K, V, M>), + 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<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! + EMPTY_BUCKET => SafeHash { hash: 0x8000_0000_0000_0000 }, + h => SafeHash { hash: h }, + } +} + +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 (minimum required malloc alignment, hash_offset, +// key_offset, val_offset, array_size), from the start of a mallocated array. +fn calculate_offsets( + hash_size: uint, hash_align: uint, + keys_size: uint, keys_align: uint, + vals_size: uint, vals_align: uint) -> (uint, uint, uint, uint, uint) { + + let hash_offset = 0; + let end_of_hashes = hash_offset + hash_size; + + let keys_offset = round_up_to_next(end_of_hashes, keys_align); + let end_of_keys = keys_offset + keys_size; + + let vals_offset = round_up_to_next(end_of_keys, 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, keys_offset, vals_offset, end_of_vals) +} + +#[test] +fn test_offset_calculation() { + assert_eq!(calculate_offsets(128, 8, 15, 1, 4, 4 ), (8, 0, 128, 144, 148)); + assert_eq!(calculate_offsets(3, 1, 2, 1, 1, 1 ), (1, 0, 3, 5, 6)); + assert_eq!(calculate_offsets(6, 2, 12, 4, 24, 8), (8, 0, 8, 24, 48)); +} + +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, + }; + } + let hashes_size = capacity.checked_mul(&size_of::<u64>()) + .expect("capacity overflow"); + let keys_size = capacity.checked_mul(&size_of::< K >()) + .expect("capacity overflow"); + let vals_size = capacity.checked_mul(&size_of::< V >()) + .expect("capacity overflow"); + + // 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_offsets( + hashes_size, min_align_of::<u64>(), + keys_size, min_align_of::< K >(), + vals_size, min_align_of::< V >()); + + let buffer = allocate(size, malloc_alignment); + + let hashes = buffer.offset(hash_offset as int) as *mut u64; + + RawTable { + capacity: capacity, + size: 0, + hashes: hashes, + } + } + + fn as_mut_ptrs(&self) -> RawBucket<K, V> { + let hashes_size = self.capacity * size_of::<u64>(); + let keys_size = self.capacity * size_of::<K>(); + + let keys_offset = (hashes_size + min_align_of::< K >() - 1) & !(min_align_of::< K >() - 1); + let end_of_keys = keys_offset + keys_size; + + let vals_offset = (end_of_keys + min_align_of::< V >() - 1) & !(min_align_of::< V >() - 1); + + let buffer = self.hashes as *mut u8; + + 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); + set_memory(ret.hashes, 0u8, 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 ptrs<'a>(&'a self) -> RawBuckets<'a, K, V> { + RawBuckets { + raw: self.as_mut_ptrs(), + hashes_end: unsafe { + self.hashes.offset(self.capacity as int) + } + } + } + + pub fn iter<'a>(&'a self) -> Entries<'a, K, V> { + Entries { + iter: self.ptrs(), + elems_left: self.size(), + } + } + + pub fn mut_iter<'a>(&'a mut self) -> MutEntries<'a, K, V> { + MutEntries { + iter: self.ptrs(), + elems_left: self.size(), + } + } + + pub fn move_iter(self) -> MoveEntries<K, V> { + MoveEntries { + iter: self.ptrs(), + table: self, + } + } + + pub fn rev_move_buckets<'a>(&'a mut self) -> RevMoveBuckets<'a, K, V> { + let raw_bucket = self.as_mut_ptrs(); + unsafe { + RevMoveBuckets { + raw: raw_bucket.offset(self.capacity as int), + hashes_end: raw_bucket.hash, + elems_left: self.size + } + } + } +} + +pub struct RawBuckets<'a, K, V> { + raw: RawBucket<K, V>, + hashes_end: *mut u64 +} + +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 { + let prev = ptr::replace(&mut self.raw, self.raw.offset(1)); + if *prev.hash != EMPTY_BUCKET { + return Some(prev); + } + } + } + + None + } +} + +pub struct RevMoveBuckets<'a, K, V> { + raw: RawBucket<K, V>, + hashes_end: *mut u64, + elems_left: uint +} + +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) + )); + } + } + } + } +} + +// `read_all_mut` casts a `*u64` to a `*SafeHash`. Since we statically +// ensure that a `FullIndex` 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), `read_all_mut` needs to be +// modified to no longer assume this. +#[test] +fn can_alias_safehash_as_u64() { + assert_eq!(size_of::<SafeHash>(), size_of::<u64>()) +} + +/// Note: stage0-specific version that lacks bound. +#[cfg(stage0)] +pub struct Entries<'a, K, V> { + iter: RawBuckets<'a, K, V>, + elems_left: uint, +} + +/// Iterator over shared references to entries in a table. +#[cfg(not(stage0))] +pub struct Entries<'a, K: 'a, V: 'a> { + iter: RawBuckets<'a, K, V>, + elems_left: uint, +} + +/// Note: stage0-specific version that lacks bound. +#[cfg(stage0)] +pub struct MutEntries<'a, K, V> { + iter: RawBuckets<'a, K, V>, + elems_left: uint, +} + +/// Iterator over mutable references to entries in a table. +#[cfg(not(stage0))] +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(); + mem::overwrite(new_buckets.raw.key, k); + mem::overwrite(new_buckets.raw.val, v); + } + _ => { + *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 in reverse because we're likely to have partially taken + // some elements out with `.move_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. + // Avoid double free of elements already moved out. + 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_offsets(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. + } + + self.hashes = RawPtr::null(); + } +} |