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harfbuzz/src/hb-map.hh

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/*
* Copyright © 2018 Google, Inc.
*
* This is part of HarfBuzz, a text shaping library.
*
* Permission is hereby granted, without written agreement and without
* license or royalty fees, to use, copy, modify, and distribute this
* software and its documentation for any purpose, provided that the
* above copyright notice and the following two paragraphs appear in
* all copies of this software.
*
* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*
* Google Author(s): Behdad Esfahbod
*/
#ifndef HB_MAP_HH
#define HB_MAP_HH
#include "hb.hh"
#include "hb-set.hh"
/*
* hb_hashmap_t
*/
extern HB_INTERNAL const hb_codepoint_t minus_1;
template <typename K, typename V,
bool minus_one = false>
struct hb_hashmap_t
{
hb_hashmap_t () { init (); }
~hb_hashmap_t () { fini (); }
hb_hashmap_t (const hb_hashmap_t& o) : hb_hashmap_t () { resize (o.population); hb_copy (o, *this); }
hb_hashmap_t (hb_hashmap_t&& o) : hb_hashmap_t () { hb_swap (*this, o); }
hb_hashmap_t& operator= (const hb_hashmap_t& o) { reset (); resize (o.population); hb_copy (o, *this); return *this; }
hb_hashmap_t& operator= (hb_hashmap_t&& o) { hb_swap (*this, o); return *this; }
hb_hashmap_t (std::initializer_list<hb_pair_t<K, V>> lst) : hb_hashmap_t ()
{
for (auto&& item : lst)
set (item.first, item.second);
}
template <typename Iterable,
hb_requires (hb_is_iterable (Iterable))>
hb_hashmap_t (const Iterable &o) : hb_hashmap_t ()
{
auto iter = hb_iter (o);
if (iter.is_random_access_iterator)
resize (hb_len (iter));
hb_copy (iter, *this);
}
struct item_t
{
K key;
uint32_t hash : 30;
uint32_t is_used_ : 1;
uint32_t is_tombstone_ : 1;
V value;
item_t () : key (),
hash (0),
is_used_ (false), is_tombstone_ (false),
value () {}
bool is_used () const { return is_used_; }
void set_used (bool is_used) { is_used_ = is_used; }
bool is_tombstone () const { return is_tombstone_; }
void set_tombstone (bool is_tombstone) { is_tombstone_ = is_tombstone; }
bool is_real () const { return is_used_ && !is_tombstone_; }
template <bool v = minus_one,
hb_enable_if (v == false)>
static inline const V& default_value () { return Null(V); };
template <bool v = minus_one,
hb_enable_if (v == true)>
static inline const V& default_value ()
{
static_assert (hb_is_same (V, hb_codepoint_t), "");
return minus_1;
};
bool operator == (const K &o) const { return hb_deref (key) == hb_deref (o); }
bool operator == (const item_t &o) const { return *this == o.key; }
hb_pair_t<K, V> get_pair() const { return hb_pair_t<K, V> (key, value); }
hb_pair_t<const K &, const V &> get_pair_ref() const { return hb_pair_t<const K &, const V &> (key, value); }
uint32_t total_hash () const
{ return (hash * 31) + hb_hash (value); }
};
hb_object_header_t header;
unsigned int successful : 1; /* Allocations successful */
unsigned int population : 31; /* Not including tombstones. */
unsigned int occupancy; /* Including tombstones. */
unsigned int mask;
unsigned int prime;
item_t *items;
friend void swap (hb_hashmap_t& a, hb_hashmap_t& b)
{
if (unlikely (!a.successful || !b.successful))
return;
unsigned tmp = a.population;
a.population = b.population;
b.population = tmp;
//hb_swap (a.population, b.population);
hb_swap (a.occupancy, b.occupancy);
hb_swap (a.mask, b.mask);
hb_swap (a.prime, b.prime);
hb_swap (a.items, b.items);
}
void init ()
{
hb_object_init (this);
successful = true;
population = occupancy = 0;
mask = 0;
prime = 0;
items = nullptr;
}
void fini ()
{
hb_object_fini (this);
if (likely (items)) {
unsigned size = mask + 1;
for (unsigned i = 0; i < size; i++)
items[i].~item_t ();
hb_free (items);
items = nullptr;
}
population = occupancy = 0;
}
void reset ()
{
successful = true;
clear ();
}
bool in_error () const { return !successful; }
bool resize (unsigned new_population = 0)
{
if (unlikely (!successful)) return false;
if (new_population != 0 && (new_population + new_population / 2) < mask) return true;
unsigned int power = hb_bit_storage (hb_max ((unsigned) population, new_population) * 2 + 8);
unsigned int new_size = 1u << power;
item_t *new_items = (item_t *) hb_malloc ((size_t) new_size * sizeof (item_t));
if (unlikely (!new_items))
{
successful = false;
return false;
}
for (auto &_ : hb_iter (new_items, new_size))
new (&_) item_t ();
unsigned int old_size = size ();
item_t *old_items = items;
/* Switch to new, empty, array. */
population = occupancy = 0;
mask = new_size - 1;
prime = prime_for (power);
items = new_items;
/* Insert back old items. */
for (unsigned int i = 0; i < old_size; i++)
{
if (old_items[i].is_real ())
{
set_with_hash (std::move (old_items[i].key),
old_items[i].hash,
std::move (old_items[i].value));
}
old_items[i].~item_t ();
}
hb_free (old_items);
return true;
}
template <typename KK, typename VV>
bool set_with_hash (KK&& key, uint32_t hash, VV&& value, bool is_delete=false)
{
if (unlikely (!successful)) return false;
if (unlikely ((occupancy + occupancy / 2) >= mask && !resize ())) return false;
item_t &item = item_for_hash (key, hash);
if (is_delete && !(item == key))
return true; /* Trying to delete non-existent key. */
if (item.is_used ())
{
occupancy--;
if (!item.is_tombstone ())
population--;
}
item.key = std::forward<KK> (key);
item.value = std::forward<VV> (value);
item.hash = hash;
item.set_used (true);
item.set_tombstone (is_delete);
occupancy++;
if (!is_delete)
population++;
return true;
}
template <typename VV>
bool set (const K &key, VV&& value) { return set_with_hash (key, hb_hash (key), std::forward<VV> (value)); }
template <typename VV>
bool set (K &&key, VV&& value) { return set_with_hash (std::move (key), hb_hash (key), std::forward<VV> (value)); }
const V& get_with_hash (const K &key, uint32_t hash) const
{
if (unlikely (!items)) return item_t::default_value ();
auto &item = item_for_hash (key, hash);
return item.is_real () && item == key ? item.value : item_t::default_value ();
}
const V& get (const K &key) const
{
if (unlikely (!items)) return item_t::default_value ();
return get_with_hash (key, hb_hash (key));
}
void del (const K &key) { set_with_hash (key, hb_hash (key), item_t::default_value (), true); }
/* Has interface. */
const V& operator [] (K k) const { return get (k); }
template <typename VV=V>
bool has (K key, VV **vp = nullptr) const
{
if (unlikely (!items))
return false;
auto &item = item_for_hash (key, hb_hash (key));
if (item.is_real () && item == key)
{
if (vp) *vp = std::addressof (item.value);
return true;
}
else
return false;
}
/* Projection. */
V operator () (K k) const { return get (k); }
unsigned size () const { return mask ? mask + 1 : 0; }
void clear ()
{
if (unlikely (!successful)) return;
for (auto &_ : hb_iter (items, size ()))
{
/* Reconstruct items. */
_.~item_t ();
new (&_) item_t ();
}
population = occupancy = 0;
}
bool is_empty () const { return population == 0; }
explicit operator bool () const { return !is_empty (); }
uint32_t hash () const
{
return
+ iter_items ()
| hb_reduce ([] (uint32_t h, const item_t &_) { return h ^ _.total_hash (); }, (uint32_t) 0u)
;
}
bool is_equal (const hb_hashmap_t &other) const
{
if (population != other.population) return false;
for (auto pair : iter ())
if (other.get (pair.first) != pair.second)
return false;
return true;
}
bool operator == (const hb_hashmap_t &other) const { return is_equal (other); }
bool operator != (const hb_hashmap_t &other) const { return !is_equal (other); }
unsigned int get_population () const { return population; }
void update (const hb_hashmap_t &other)
{
if (unlikely (!successful)) return;
hb_copy (other, *this);
}
void keys (hb_set_t &keys_) const
{
hb_copy (keys() , keys_);
}
void values (hb_set_t &values_) const
{
hb_copy (values() , values_);
}
/*
* Iterator
*/
auto iter_items () const HB_AUTO_RETURN
(
+ hb_iter (items, size ())
| hb_filter (&item_t::is_real)
)
auto iter_ref () const HB_AUTO_RETURN
(
+ iter_items ()
| hb_map (&item_t::get_pair_ref)
)
auto iter () const HB_AUTO_RETURN
(
+ iter_items ()
| hb_map (&item_t::get_pair)
)
auto keys_ref () const HB_AUTO_RETURN
(
+ iter_items ()
| hb_map (&item_t::key)
)
auto keys () const HB_AUTO_RETURN
(
+ keys_ref ()
| hb_map (hb_ridentity)
)
auto values_ref () const HB_AUTO_RETURN
(
+ iter_items ()
| hb_map (&item_t::value)
)
auto values () const HB_AUTO_RETURN
(
+ values_ref ()
| hb_map (hb_ridentity)
)
/* C iterator. */
bool next (int *idx,
K *key,
V *value) const
{
unsigned i = (unsigned) (*idx + 1);
unsigned count = size ();
while (i < count && !items[i].is_real ())
i++;
if (i >= count)
{
*idx = -1;
return false;
}
*key = items[i].key;
*value = items[i].value;
*idx = (signed) i;
return true;
}
/* Sink interface. */
hb_hashmap_t& operator << (const hb_pair_t<K, V>& v)
{ set (v.first, v.second); return *this; }
hb_hashmap_t& operator << (const hb_pair_t<K, V&&>& v)
{ set (v.first, std::move (v.second)); return *this; }
hb_hashmap_t& operator << (const hb_pair_t<K&&, V>& v)
{ set (std::move (v.first), v.second); return *this; }
hb_hashmap_t& operator << (const hb_pair_t<K&&, V&&>& v)
{ set (std::move (v.first), std::move (v.second)); return *this; }
item_t& item_for_hash (const K &key, uint32_t hash) const
{
hash &= 0x3FFFFFFF; // We only store lower 30bit of hash
unsigned int i = hash % prime;
unsigned int step = 0;
unsigned int tombstone = (unsigned) -1;
while (items[i].is_used ())
{
if (items[i].hash == hash && items[i] == key)
return items[i];
if (tombstone == (unsigned) -1 && items[i].is_tombstone ())
tombstone = i;
i = (i + ++step) & mask;
}
return items[tombstone == (unsigned) -1 ? i : tombstone];
}
static unsigned int prime_for (unsigned int shift)
{
/* Following comment and table copied from glib. */
/* Each table size has an associated prime modulo (the first prime
* lower than the table size) used to find the initial bucket. Probing
* then works modulo 2^n. The prime modulo is necessary to get a
* good distribution with poor hash functions.
*/
/* Not declaring static to make all kinds of compilers happy... */
/*static*/ const unsigned int prime_mod [32] =
{
1, /* For 1 << 0 */
2,
3,
7,
13,
31,
61,
127,
251,
509,
1021,
2039,
4093,
8191,
16381,
32749,
65521, /* For 1 << 16 */
131071,
262139,
524287,
1048573,
2097143,
4194301,
8388593,
16777213,
33554393,
67108859,
134217689,
268435399,
536870909,
1073741789,
2147483647 /* For 1 << 31 */
};
if (unlikely (shift >= ARRAY_LENGTH (prime_mod)))
return prime_mod[ARRAY_LENGTH (prime_mod) - 1];
return prime_mod[shift];
}
};
/*
* hb_map_t
*/
struct hb_map_t : hb_hashmap_t<hb_codepoint_t,
hb_codepoint_t,
true>
{
using hashmap = hb_hashmap_t<hb_codepoint_t,
hb_codepoint_t,
true>;
~hb_map_t () = default;
hb_map_t () : hashmap () {}
hb_map_t (const hb_map_t &o) : hashmap ((hashmap &) o) {}
hb_map_t (hb_map_t &&o) : hashmap (std::move ((hashmap &) o)) {}
hb_map_t& operator= (const hb_map_t&) = default;
hb_map_t& operator= (hb_map_t&&) = default;
hb_map_t (std::initializer_list<hb_pair_t<hb_codepoint_t, hb_codepoint_t>> lst) : hashmap (lst) {}
template <typename Iterable,
hb_requires (hb_is_iterable (Iterable))>
hb_map_t (const Iterable &o) : hashmap (o) {}
};
#endif /* HB_MAP_HH */
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