Hash :
be5cdcdf
Author :
Date :
2019-10-22T11:55:04
Store the hash value of a key in item_t in hb_map to reduce the number of hash computations.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328
/*
* 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 == (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 ()
{
free (items);
items = nullptr;
population = occupancy = 0;
}
void fini ()
{
hb_object_fini (this);
fini_shallow ();
}
void reset ()
{
if (unlikely (hb_object_is_immutable (this)))
return;
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 *) malloc ((size_t) new_size * sizeof (item_t));
if (unlikely (!new_items))
{
successful = false;
return false;
}
+ hb_iter (new_items, new_size)
| hb_apply (&item_t::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);
free (old_items);
return true;
}
void set (K key, V value)
{
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 (hb_object_is_immutable (this)))
return;
if (items)
+ hb_iter (items, mask + 1)
| hb_apply (&item_t::clear)
;
population = occupancy = 0;
}
bool is_empty () const { return population == 0; }
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<K, V, kINVALID, vINVALID>& operator << (const hb_pair_t<K, V>& v)
{ set (v.first, v.second); return *this; }
protected:
void set_with_hash (K key, uint32_t hash, V value)
{
if (unlikely (!successful)) return;
if (unlikely (key == kINVALID)) return;
if ((occupancy + occupancy / 2) >= mask && !resize ()) return;
unsigned int i = bucket_for_hash (key, hash);
if (value == vINVALID && items[i].key != key)
return; /* 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++;
}
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 */