harfbuzz/src/hb-map-private.hh

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/*
* Copyright © 2012,2017 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_PRIVATE_HH
#define HB_MAP_PRIVATE_HH
#include "hb-private.hh"
#include "hb-object-private.hh"
template <typename T>
inline uint32_t Hash (const T &v)
{
/* Knuth's multiplicative method: */
return (uint32_t) v * 2654435761u;
}
/*
* hb_map_t
*/
struct hb_map_t
{
struct item_t
{
hb_codepoint_t key;
hb_codepoint_t value;
inline bool is_unused (void) const { return key == INVALID; }
inline bool is_tombstone (void) const { return key != INVALID && value == INVALID; }
};
hb_object_header_t header;
ASSERT_POD ();
bool in_error;
unsigned int occupancy; /* Including tombstones. */
unsigned int mask;
unsigned int prime;
item_t *items;
inline void init_shallow (void)
{
in_error = false;
occupancy = 0;
mask = 0;
prime = 0;
items = nullptr;
}
inline void init (void)
{
hb_object_init (this);
init_shallow ();
}
inline void fini_shallow (void)
{
free (items);
}
inline void fini (void)
{
hb_object_fini (this);
fini_shallow ();
}
inline bool resize (void)
{
if (unlikely (in_error)) return false;
unsigned int power = _hb_bit_storage (occupancy * 2 + 8) - 1;
unsigned int new_size = 1u << power;
item_t *new_items = (item_t *) malloc ((size_t) new_size * sizeof (item_t));
if (unlikely (!new_items))
{
in_error = true;
return false;
}
memset (new_items, 0xFF, (size_t) new_size * sizeof (item_t));
unsigned int old_size = mask + 1;
item_t *old_items = items;
/* Switch to new, empty, array. */
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].key != INVALID && old_items[i].value != INVALID)
set (old_items[i].key, old_items[i].value);
free (old_items);
return true;
}
inline void set (hb_codepoint_t key, hb_codepoint_t value)
{
if (unlikely (in_error)) return;
if ((occupancy + occupancy / 2) > mask && !resize ()) return;
unsigned int i = bucket_for (key);
if (items[i].key != key)
{
if (items[i].key == INVALID && key != INVALID)
occupancy++;
items[i].key = key;
}
items[i].value = value;
}
inline hb_codepoint_t get (hb_codepoint_t key) const
{
if (unlikely (in_error)) return INVALID;
if (unlikely (!items)) return INVALID;
unsigned int i = bucket_for (key);
return items[i].key == key ? items[i].value : INVALID;
}
inline void del (hb_codepoint_t key)
{
if (unlikely (in_error)) return;
if (unlikely (!items)) return;
unsigned int i = bucket_for (key);
items[i].value = INVALID;
}
inline bool has (hb_codepoint_t key) const
{
return get (key) != INVALID;
}
static const hb_codepoint_t INVALID = HB_MAP_VALUE_INVALID;
protected:
static HB_INTERNAL unsigned int prime_for (unsigned int shift);
unsigned int bucket_for (hb_codepoint_t key) const
{
unsigned int i = Hash (key) % prime;
unsigned int step = 0;
unsigned int tombstone = INVALID;
while (!items[i].is_unused ())
{
if (items[i].key == key)
return i;
if (tombstone == INVALID && items[i].is_tombstone ())
tombstone = i;
i = (i + ++step) & mask;
}
return tombstone == INVALID ? i : tombstone;
}
private:
HB_DISALLOW_COPY_AND_ASSIGN (hb_map_t);
};
#endif /* HB_MAP_PRIVATE_HH */