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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"
/*
* hb_hashmap_t
*/
template <typename K, typename V,
K kINVALID = hb_is_pointer (K) ? 0 : hb_is_signed (K) ? hb_int_min (K) : (K) -1,
V vINVALID = hb_is_pointer (V) ? 0 : hb_is_signed (V) ? hb_int_min (V) : (V) -1>
struct hb_hashmap_t
{
HB_DELETE_COPY_ASSIGN (hb_hashmap_t);
hb_hashmap_t () { init (); }
~hb_hashmap_t () { fini (); }
static_assert (hb_is_integral (K) || hb_is_pointer (K), "");
static_assert (hb_is_integral (V) || hb_is_pointer (V), "");
struct item_t
{
K key;
V value;
uint32_t hash;
void clear () { key = kINVALID; value = vINVALID; hash = 0; }
bool operator == (const K &o) { return hb_deref (key) == hb_deref (o); }
bool operator == (const item_t &o) { return *this == o.key; }
bool is_unused () const { return key == kINVALID; }
bool is_tombstone () const { return key != kINVALID && value == vINVALID; }
bool is_real () const { return key != kINVALID && value != vINVALID; }
hb_pair_t<K, V> get_pair() const { return hb_pair_t<K, V> (key, value); }
};
hb_object_header_t header;
bool successful; /* Allocations successful */
unsigned int population; /* Not including tombstones. */
unsigned int occupancy; /* Including tombstones. */
unsigned int mask;
unsigned int prime;
item_t *items;
void init_shallow ()
{
successful = true;
population = occupancy = 0;
mask = 0;
prime = 0;
items = nullptr;
}
void init ()
{
hb_object_init (this);
init_shallow ();
}
void fini_shallow ()
{
hb_free (items);
items = nullptr;
population = occupancy = 0;
}
void fini ()
{
hb_object_fini (this);
fini_shallow ();
}
void reset ()
{
successful = true;
clear ();
}
bool in_error () const { return !successful; }
bool resize ()
{
if (unlikely (!successful)) return false;
unsigned int power = hb_bit_storage (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))
_.clear ();
unsigned int old_size = mask + 1;
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. */
if (old_items)
for (unsigned int i = 0; i < old_size; i++)
if (old_items[i].is_real ())
set_with_hash (old_items[i].key,
old_items[i].hash,
old_items[i].value);
hb_free (old_items);
return true;
}
bool set (K key, V value)
{
return set_with_hash (key, hb_hash (key), value);
}
V get (K key) const
{
if (unlikely (!items)) return vINVALID;
unsigned int i = bucket_for (key);
return items[i].is_real () && items[i] == key ? items[i].value : vINVALID;
}
void del (K key) { set (key, vINVALID); }
/* Has interface. */
static constexpr V SENTINEL = vINVALID;
typedef V value_t;
value_t operator [] (K k) const { return get (k); }
bool has (K k, V *vp = nullptr) const
{
V v = (*this)[k];
if (vp) *vp = v;
return v != SENTINEL;
}
/* Projection. */
V operator () (K k) const { return get (k); }
void clear ()
{
if (unlikely (!successful)) return;
if (items)
for (auto &_ : hb_iter (items, mask + 1))
_.clear ();
population = occupancy = 0;
}
bool is_empty () const { return population == 0; }
explicit operator bool () const { return !is_empty (); }
unsigned int get_population () const { return population; }
/*
* Iterator
*/
auto iter () const HB_AUTO_RETURN
(
+ hb_array (items, mask ? mask + 1 : 0)
| hb_filter (&item_t::is_real)
| hb_map (&item_t::get_pair)
)
auto keys () const HB_AUTO_RETURN
(
+ hb_array (items, mask ? mask + 1 : 0)
| hb_filter (&item_t::is_real)
| hb_map (&item_t::key)
| hb_map (hb_ridentity)
)
auto values () const HB_AUTO_RETURN
(
+ hb_array (items, mask ? mask + 1 : 0)
| hb_filter (&item_t::is_real)
| hb_map (&item_t::value)
| hb_map (hb_ridentity)
)
/* Sink interface. */
hb_hashmap_t& operator << (const hb_pair_t<K, V>& v)
{ set (v.first, v.second); return *this; }
protected:
bool set_with_hash (K key, uint32_t hash, V value)
{
if (unlikely (!successful)) return false;
if (unlikely (key == kINVALID)) return true;
if (unlikely ((occupancy + occupancy / 2) >= mask && !resize ())) return false;
unsigned int i = bucket_for_hash (key, hash);
if (value == vINVALID && items[i].key != key)
return true; /* Trying to delete non-existent key. */
if (!items[i].is_unused ())
{
occupancy--;
if (!items[i].is_tombstone ())
population--;
}
items[i].key = key;
items[i].value = value;
items[i].hash = hash;
occupancy++;
if (!items[i].is_tombstone ())
population++;
return true;
}
unsigned int bucket_for (K key) const
{
return bucket_for_hash (key, hb_hash (key));
}
unsigned int bucket_for_hash (K key, uint32_t hash) const
{
unsigned int i = hash % prime;
unsigned int step = 0;
unsigned int tombstone = (unsigned) -1;
while (!items[i].is_unused ())
{
if (items[i].hash == hash && items[i] == key)
return i;
if (tombstone == (unsigned) -1 && items[i].is_tombstone ())
tombstone = i;
i = (i + ++step) & mask;
}
return 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,
HB_MAP_VALUE_INVALID,
HB_MAP_VALUE_INVALID> {};
#endif /* HB_MAP_HH */