/*
* Copyright © 2012 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_SET_PRIVATE_HH
#define HB_SET_PRIVATE_HH
#include "hb-private.hh"
#include "hb-object-private.hh"
/*
* The set digests here implement various "filters" that support
* "approximate member query". Conceptually these are like Bloom
* Filter and Quotient Filter, however, much smaller, faster, and
* designed to fit the requirements of our uses for glyph coverage
* queries.
*
* Our filters are highly accurate if the lookup covers fairly local
* set of glyphs, but fully flooded and ineffective if coverage is
* all over the place.
*
* The frozen-set can be used instead of a digest, to trade more
* memory for 100% accuracy, but in practice, that doesn't look like
* an attractive trade-off.
*/
template <typename mask_t, unsigned int shift>
struct hb_set_digest_lowest_bits_t
{
ASSERT_POD ();
static const unsigned int mask_bytes = sizeof (mask_t);
static const unsigned int mask_bits = sizeof (mask_t) * 8;
static const unsigned int num_bits = 0
+ (mask_bytes >= 1 ? 3 : 0)
+ (mask_bytes >= 2 ? 1 : 0)
+ (mask_bytes >= 4 ? 1 : 0)
+ (mask_bytes >= 8 ? 1 : 0)
+ (mask_bytes >= 16? 1 : 0)
+ 0;
ASSERT_STATIC (shift < sizeof (hb_codepoint_t) * 8);
ASSERT_STATIC (shift + num_bits <= sizeof (hb_codepoint_t) * 8);
inline void init (void) {
mask = 0;
}
inline void add (hb_codepoint_t g) {
mask |= mask_for (g);
}
inline void add_range (hb_codepoint_t a, hb_codepoint_t b) {
if ((b >> shift) - (a >> shift) >= mask_bits - 1)
mask = (mask_t) -1;
else {
mask_t ma = mask_for (a);
mask_t mb = mask_for (b);
mask |= mb + (mb - ma) - (mb < ma);
}
}
inline bool may_have (hb_codepoint_t g) const {
return !!(mask & mask_for (g));
}
private:
static inline mask_t mask_for (hb_codepoint_t g) {
return ((mask_t) 1) << ((g >> shift) & (mask_bits - 1));
}
mask_t mask;
};
template <typename head_t, typename tail_t>
struct hb_set_digest_combiner_t
{
ASSERT_POD ();
inline void init (void) {
head.init ();
tail.init ();
}
inline void add (hb_codepoint_t g) {
head.add (g);
tail.add (g);
}
inline void add_range (hb_codepoint_t a, hb_codepoint_t b) {
head.add_range (a, b);
tail.add_range (a, b);
}
inline bool may_have (hb_codepoint_t g) const {
return head.may_have (g) && tail.may_have (g);
}
private:
head_t head;
tail_t tail;
};
/*
* hb_set_digest_t
*
* This is a combination of digests that performs "best".
* There is not much science to this: it's a result of intuition
* and testing.
*/
typedef hb_set_digest_combiner_t
<
hb_set_digest_lowest_bits_t<unsigned long, 4>,
hb_set_digest_combiner_t
<
hb_set_digest_lowest_bits_t<unsigned long, 0>,
hb_set_digest_lowest_bits_t<unsigned long, 9>
>
> hb_set_digest_t;
/*
* hb_set_t
*/
/* TODO Make this faster and memmory efficient. */
struct hb_set_t
{
friend struct hb_frozen_set_t;
hb_object_header_t header;
ASSERT_POD ();
bool in_error;
inline void init (void) {
hb_object_init (this);
clear ();
}
inline void fini (void) {
}
inline void clear (void) {
if (unlikely (hb_object_is_inert (this)))
return;
in_error = false;
memset (elts, 0, sizeof elts);
}
inline bool is_empty (void) const {
for (unsigned int i = 0; i < ARRAY_LENGTH (elts); i++)
if (elts[i])
return false;
return true;
}
inline void add (hb_codepoint_t g)
{
if (unlikely (in_error)) return;
if (unlikely (g == INVALID)) return;
if (unlikely (g > MAX_G)) return;
elt (g) |= mask (g);
}
inline void add_range (hb_codepoint_t a, hb_codepoint_t b)
{
if (unlikely (in_error)) return;
/* TODO Speedup */
for (unsigned int i = a; i < b + 1; i++)
add (i);
}
inline void del (hb_codepoint_t g)
{
if (unlikely (in_error)) return;
if (unlikely (g > MAX_G)) return;
elt (g) &= ~mask (g);
}
inline void del_range (hb_codepoint_t a, hb_codepoint_t b)
{
if (unlikely (in_error)) return;
/* TODO Speedup */
for (unsigned int i = a; i < b + 1; i++)
del (i);
}
inline bool has (hb_codepoint_t g) const
{
if (unlikely (g > MAX_G)) return false;
return !!(elt (g) & mask (g));
}
inline bool intersects (hb_codepoint_t first,
hb_codepoint_t last) const
{
if (unlikely (first > MAX_G)) return false;
if (unlikely (last > MAX_G)) last = MAX_G;
unsigned int end = last + 1;
for (hb_codepoint_t i = first; i < end; i++)
if (has (i))
return true;
return false;
}
inline bool is_equal (const hb_set_t *other) const
{
for (unsigned int i = 0; i < ELTS; i++)
if (elts[i] != other->elts[i])
return false;
return true;
}
inline void set (const hb_set_t *other)
{
if (unlikely (in_error)) return;
for (unsigned int i = 0; i < ELTS; i++)
elts[i] = other->elts[i];
}
inline void union_ (const hb_set_t *other)
{
if (unlikely (in_error)) return;
for (unsigned int i = 0; i < ELTS; i++)
elts[i] |= other->elts[i];
}
inline void intersect (const hb_set_t *other)
{
if (unlikely (in_error)) return;
for (unsigned int i = 0; i < ELTS; i++)
elts[i] &= other->elts[i];
}
inline void subtract (const hb_set_t *other)
{
if (unlikely (in_error)) return;
for (unsigned int i = 0; i < ELTS; i++)
elts[i] &= ~other->elts[i];
}
inline void symmetric_difference (const hb_set_t *other)
{
if (unlikely (in_error)) return;
for (unsigned int i = 0; i < ELTS; i++)
elts[i] ^= other->elts[i];
}
inline void invert (void)
{
if (unlikely (in_error)) return;
for (unsigned int i = 0; i < ELTS; i++)
elts[i] = ~elts[i];
}
inline bool next (hb_codepoint_t *codepoint) const
{
if (unlikely (*codepoint == INVALID)) {
hb_codepoint_t i = get_min ();
if (i != INVALID) {
*codepoint = i;
return true;
} else {
*codepoint = INVALID;
return false;
}
}
for (hb_codepoint_t i = *codepoint + 1; i < MAX_G + 1; i++)
if (has (i)) {
*codepoint = i;
return true;
}
*codepoint = INVALID;
return false;
}
inline bool next_range (hb_codepoint_t *first, hb_codepoint_t *last) const
{
hb_codepoint_t i;
i = *last;
if (!next (&i))
{
*last = *first = INVALID;
return false;
}
*last = *first = i;
while (next (&i) && i == *last + 1)
(*last)++;
return true;
}
inline unsigned int get_population (void) const
{
unsigned int count = 0;
for (unsigned int i = 0; i < ELTS; i++)
count += _hb_popcount32 (elts[i]);
return count;
}
inline hb_codepoint_t get_min (void) const
{
for (unsigned int i = 0; i < ELTS; i++)
if (elts[i])
for (unsigned int j = 0; j < BITS; j++)
if (elts[i] & (1u << j))
return i * BITS + j;
return INVALID;
}
inline hb_codepoint_t get_max (void) const
{
for (unsigned int i = ELTS; i; i--)
if (elts[i - 1])
for (unsigned int j = BITS; j; j--)
if (elts[i - 1] & (1u << (j - 1)))
return (i - 1) * BITS + (j - 1);
return INVALID;
}
typedef uint32_t elt_t;
static const unsigned int MAX_G = 65536 - 1; /* XXX Fix this... */
static const unsigned int SHIFT = 5;
static const unsigned int BITS = (1 << SHIFT);
static const unsigned int MASK = BITS - 1;
static const unsigned int ELTS = (MAX_G + 1 + (BITS - 1)) / BITS;
static const hb_codepoint_t INVALID = HB_SET_VALUE_INVALID;
elt_t &elt (hb_codepoint_t g) { return elts[g >> SHIFT]; }
elt_t const &elt (hb_codepoint_t g) const { return elts[g >> SHIFT]; }
elt_t mask (hb_codepoint_t g) const { return elt_t (1) << (g & MASK); }
elt_t elts[ELTS]; /* XXX 8kb */
ASSERT_STATIC (sizeof (elt_t) * 8 == BITS);
ASSERT_STATIC (sizeof (elt_t) * 8 * ELTS > MAX_G);
};
struct hb_frozen_set_t
{
static const unsigned int SHIFT = hb_set_t::SHIFT;
static const unsigned int BITS = hb_set_t::BITS;
static const unsigned int MASK = hb_set_t::MASK;
typedef hb_set_t::elt_t elt_t;
inline void init (const hb_set_t &set)
{
start = count = 0;
elts = NULL;
unsigned int max = set.get_max ();
if (max == set.INVALID)
return;
unsigned int min = set.get_min ();
const elt_t &min_elt = set.elt (min);
start = min & ~MASK;
count = max - start + 1;
unsigned int num_elts = (count + BITS - 1) / BITS;
unsigned int elts_size = num_elts * sizeof (elt_t);
elts = (elt_t *) malloc (elts_size);
if (unlikely (!elts))
{
start = count = 0;
return;
}
memcpy (elts, &min_elt, elts_size);
}
inline void fini (void)
{
if (elts)
free (elts);
}
inline bool has (hb_codepoint_t g) const
{
/* hb_codepoint_t is unsigned. */
g -= start;
if (unlikely (g > count)) return false;
return !!(elt (g) & mask (g));
}
elt_t const &elt (hb_codepoint_t g) const { return elts[g >> SHIFT]; }
elt_t mask (hb_codepoint_t g) const { return elt_t (1) << (g & MASK); }
private:
hb_codepoint_t start, count;
elt_t *elts;
};
#endif /* HB_SET_PRIVATE_HH */