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/*
* Copyright © 2012,2017 Google, Inc.
* Copyright © 2021 Behdad Esfahbod
*
* 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_BIT_SET_HH
#define HB_BIT_SET_HH
#include "hb.hh"
#include "hb-bit-page.hh"
#include "hb-machinery.hh"
struct hb_bit_set_t
{
hb_bit_set_t () = default;
~hb_bit_set_t () = default;
hb_bit_set_t (const hb_bit_set_t& other) : hb_bit_set_t () { set (other); }
hb_bit_set_t ( hb_bit_set_t&& other) : hb_bit_set_t () { hb_swap (*this, other); }
hb_bit_set_t& operator= (const hb_bit_set_t& other) { set (other); return *this; }
hb_bit_set_t& operator= (hb_bit_set_t&& other) { hb_swap (*this, other); return *this; }
friend void swap (hb_bit_set_t &a, hb_bit_set_t &b)
{
if (likely (!a.successful || !b.successful))
return;
hb_swap (a.population, b.population);
hb_swap (a.last_page_lookup, b.last_page_lookup);
hb_swap (a.page_map, b.page_map);
hb_swap (a.pages, b.pages);
}
void init ()
{
successful = true;
population = 0;
last_page_lookup = 0;
page_map.init ();
pages.init ();
}
void fini ()
{
page_map.fini ();
pages.fini ();
}
using page_t = hb_bit_page_t;
struct page_map_t
{
int cmp (const page_map_t &o) const { return cmp (o.major); }
int cmp (uint32_t o_major) const { return (int) o_major - (int) major; }
uint32_t major;
uint32_t index;
};
bool successful = true; /* Allocations successful */
mutable unsigned int population = 0;
mutable hb_atomic_int_t last_page_lookup = 0;
hb_sorted_vector_t<page_map_t> page_map;
hb_vector_t<page_t> pages;
void err () { if (successful) successful = false; } /* TODO Remove */
bool in_error () const { return !successful; }
bool resize (unsigned int count)
{
if (unlikely (!successful)) return false;
if (unlikely (!pages.resize (count) || !page_map.resize (count)))
{
pages.resize (page_map.length);
successful = false;
return false;
}
return true;
}
void alloc (unsigned sz)
{
sz >>= (page_t::PAGE_BITS_LOG_2 - 1);
pages.alloc (sz);
page_map.alloc (sz);
}
void reset ()
{
successful = true;
clear ();
}
void clear ()
{
resize (0);
if (likely (successful))
population = 0;
}
bool is_empty () const
{
unsigned int count = pages.length;
for (unsigned int i = 0; i < count; i++)
if (!pages[i].is_empty ())
return false;
return true;
}
explicit operator bool () const { return !is_empty (); }
uint32_t hash () const
{
uint32_t h = 0;
for (auto &map : page_map)
h = h * 31 + hb_hash (map.major) + hb_hash (pages[map.index]);
return h;
}
private:
void dirty () { population = UINT_MAX; }
public:
void add (hb_codepoint_t g)
{
if (unlikely (!successful)) return;
if (unlikely (g == INVALID)) return;
dirty ();
page_t *page = page_for (g, true); if (unlikely (!page)) return;
page->add (g);
}
bool add_range (hb_codepoint_t a, hb_codepoint_t b)
{
if (unlikely (!successful)) return true; /* https://github.com/harfbuzz/harfbuzz/issues/657 */
if (unlikely (a > b || a == INVALID || b == INVALID)) return false;
dirty ();
unsigned int ma = get_major (a);
unsigned int mb = get_major (b);
if (ma == mb)
{
page_t *page = page_for (a, true); if (unlikely (!page)) return false;
page->add_range (a, b);
}
else
{
page_t *page = page_for (a, true); if (unlikely (!page)) return false;
page->add_range (a, major_start (ma + 1) - 1);
for (unsigned int m = ma + 1; m < mb; m++)
{
page = page_for (major_start (m), true); if (unlikely (!page)) return false;
page->init1 ();
}
page = page_for (b, true); if (unlikely (!page)) return false;
page->add_range (major_start (mb), b);
}
return true;
}
template <typename T>
void set_array (bool v, const T *array, unsigned int count, unsigned int stride=sizeof(T))
{
if (unlikely (!successful)) return;
if (!count) return;
dirty ();
hb_codepoint_t g = *array;
while (count)
{
unsigned int m = get_major (g);
page_t *page = page_for (g, v); if (unlikely (v && !page)) return;
unsigned int start = major_start (m);
unsigned int end = major_start (m + 1);
do
{
if (v || page) /* The v check is to optimize out the page check if v is true. */
page->set (g, v);
array = &StructAtOffsetUnaligned<T> (array, stride);
count--;
}
while (count && (g = *array, start <= g && g < end));
}
}
template <typename T>
void add_array (const T *array, unsigned int count, unsigned int stride=sizeof(T))
{ set_array (true, array, count, stride); }
template <typename T>
void add_array (const hb_array_t<const T>& arr) { add_array (&arr, arr.len ()); }
template <typename T>
void del_array (const T *array, unsigned int count, unsigned int stride=sizeof(T))
{ set_array (false, array, count, stride); }
template <typename T>
void del_array (const hb_array_t<const T>& arr) { del_array (&arr, arr.len ()); }
/* Might return false if array looks unsorted.
* Used for faster rejection of corrupt data. */
template <typename T>
bool set_sorted_array (bool v, const T *array, unsigned int count, unsigned int stride=sizeof(T))
{
if (unlikely (!successful)) return true; /* https://github.com/harfbuzz/harfbuzz/issues/657 */
if (unlikely (!count)) return true;
dirty ();
hb_codepoint_t g = *array;
hb_codepoint_t last_g = g;
while (count)
{
unsigned int m = get_major (g);
page_t *page = page_for (g, v); if (unlikely (v && !page)) return false;
unsigned int end = major_start (m + 1);
do
{
/* If we try harder we can change the following comparison to <=;
* Not sure if it's worth it. */
if (g < last_g) return false;
last_g = g;
if (v || page) /* The v check is to optimize out the page check if v is true. */
page->add (g);
array = &StructAtOffsetUnaligned<T> (array, stride);
count--;
}
while (count && (g = *array, g < end));
}
return true;
}
template <typename T>
bool add_sorted_array (const T *array, unsigned int count, unsigned int stride=sizeof(T))
{ return set_sorted_array (true, array, count, stride); }
template <typename T>
bool add_sorted_array (const hb_sorted_array_t<const T>& arr) { return add_sorted_array (&arr, arr.len ()); }
template <typename T>
bool del_sorted_array (const T *array, unsigned int count, unsigned int stride=sizeof(T))
{ return set_sorted_array (false, array, count, stride); }
template <typename T>
bool del_sorted_array (const hb_sorted_array_t<const T>& arr) { return del_sorted_array (&arr, arr.len ()); }
void del (hb_codepoint_t g)
{
if (unlikely (!successful)) return;
page_t *page = page_for (g);
if (!page)
return;
dirty ();
page->del (g);
}
private:
void del_pages (int ds, int de)
{
if (ds <= de)
{
// Pre-allocate the workspace that compact() will need so we can bail on allocation failure
// before attempting to rewrite the page map.
hb_vector_t<unsigned> compact_workspace;
if (unlikely (!allocate_compact_workspace (compact_workspace))) return;
unsigned int write_index = 0;
for (unsigned int i = 0; i < page_map.length; i++)
{
int m = (int) page_map[i].major;
if (m < ds || de < m)
page_map[write_index++] = page_map[i];
}
compact (compact_workspace, write_index);
resize (write_index);
}
}
public:
void del_range (hb_codepoint_t a, hb_codepoint_t b)
{
if (unlikely (!successful)) return;
if (unlikely (a > b || a == INVALID)) return;
dirty ();
unsigned int ma = get_major (a);
unsigned int mb = get_major (b);
/* Delete pages from ds through de if ds <= de. */
int ds = (a == major_start (ma))? (int) ma: (int) (ma + 1);
int de = (b + 1 == major_start (mb + 1))? (int) mb: ((int) mb - 1);
if (ds > de || (int) ma < ds)
{
page_t *page = page_for (a);
if (page)
{
if (ma == mb)
page->del_range (a, b);
else
page->del_range (a, major_start (ma + 1) - 1);
}
}
if (de < (int) mb && ma != mb)
{
page_t *page = page_for (b);
if (page)
page->del_range (major_start (mb), b);
}
del_pages (ds, de);
}
bool get (hb_codepoint_t g) const
{
const page_t *page = page_for (g);
if (!page)
return false;
return page->get (g);
}
/* Has interface. */
static constexpr bool SENTINEL = false;
typedef bool value_t;
value_t operator [] (hb_codepoint_t k) const { return get (k); }
bool has (hb_codepoint_t k) const { return (*this)[k] != SENTINEL; }
/* Predicate. */
bool operator () (hb_codepoint_t k) const { return has (k); }
/* Sink interface. */
hb_bit_set_t& operator << (hb_codepoint_t v)
{ add (v); return *this; }
hb_bit_set_t& operator << (const hb_pair_t<hb_codepoint_t, hb_codepoint_t>& range)
{ add_range (range.first, range.second); return *this; }
bool intersects (hb_codepoint_t first, hb_codepoint_t last) const
{
hb_codepoint_t c = first - 1;
return next (&c) && c <= last;
}
void set (const hb_bit_set_t &other)
{
if (unlikely (!successful)) return;
unsigned int count = other.pages.length;
if (unlikely (!resize (count)))
return;
population = other.population;
page_map = other.page_map;
pages = other.pages;
}
bool is_equal (const hb_bit_set_t &other) const
{
if (has_population () && other.has_population () &&
population != other.population)
return false;
unsigned int na = pages.length;
unsigned int nb = other.pages.length;
unsigned int a = 0, b = 0;
for (; a < na && b < nb; )
{
if (page_at (a).is_empty ()) { a++; continue; }
if (other.page_at (b).is_empty ()) { b++; continue; }
if (page_map[a].major != other.page_map[b].major ||
!page_at (a).is_equal (other.page_at (b)))
return false;
a++;
b++;
}
for (; a < na; a++)
if (!page_at (a).is_empty ()) { return false; }
for (; b < nb; b++)
if (!other.page_at (b).is_empty ()) { return false; }
return true;
}
bool is_subset (const hb_bit_set_t &larger_set) const
{
if (has_population () && larger_set.has_population () &&
population != larger_set.population)
return false;
uint32_t spi = 0;
for (uint32_t lpi = 0; spi < page_map.length && lpi < larger_set.page_map.length; lpi++)
{
uint32_t spm = page_map[spi].major;
uint32_t lpm = larger_set.page_map[lpi].major;
auto sp = page_at (spi);
auto lp = larger_set.page_at (lpi);
if (spm < lpm && !sp.is_empty ())
return false;
if (lpm < spm)
continue;
if (!sp.is_subset (lp))
return false;
spi++;
}
while (spi < page_map.length)
if (!page_at (spi++).is_empty ())
return false;
return true;
}
private:
bool allocate_compact_workspace (hb_vector_t<unsigned>& workspace)
{
if (unlikely (!workspace.resize (pages.length)))
{
successful = false;
return false;
}
return true;
}
/*
* workspace should be a pre-sized vector allocated to hold at exactly pages.length
* elements.
*/
void compact (hb_vector_t<unsigned>& workspace,
unsigned int length)
{
assert(workspace.length == pages.length);
hb_vector_t<unsigned>& old_index_to_page_map_index = workspace;
hb_fill (old_index_to_page_map_index.writer(), 0xFFFFFFFF);
for (unsigned i = 0; i < length; i++)
old_index_to_page_map_index[page_map[i].index] = i;
compact_pages (old_index_to_page_map_index);
}
void compact_pages (const hb_vector_t<unsigned>& old_index_to_page_map_index)
{
unsigned int write_index = 0;
for (unsigned int i = 0; i < pages.length; i++)
{
if (old_index_to_page_map_index[i] == 0xFFFFFFFF) continue;
if (write_index < i)
pages[write_index] = pages[i];
page_map[old_index_to_page_map_index[i]].index = write_index;
write_index++;
}
}
public:
void process_ (hb_bit_page_t::vector_t (*op) (const hb_bit_page_t::vector_t &, const hb_bit_page_t::vector_t &),
bool passthru_left, bool passthru_right,
const hb_bit_set_t &other)
{
if (unlikely (!successful)) return;
dirty ();
unsigned int na = pages.length;
unsigned int nb = other.pages.length;
unsigned int next_page = na;
unsigned int count = 0, newCount = 0;
unsigned int a = 0, b = 0;
unsigned int write_index = 0;
// Pre-allocate the workspace that compact() will need so we can bail on allocation failure
// before attempting to rewrite the page map.
hb_vector_t<unsigned> compact_workspace;
if (!passthru_left && unlikely (!allocate_compact_workspace (compact_workspace))) return;
for (; a < na && b < nb; )
{
if (page_map[a].major == other.page_map[b].major)
{
if (!passthru_left)
{
// Move page_map entries that we're keeping from the left side set
// to the front of the page_map vector. This isn't necessary if
// passthru_left is set since no left side pages will be removed
// in that case.
if (write_index < a)
page_map[write_index] = page_map[a];
write_index++;
}
count++;
a++;
b++;
}
else if (page_map[a].major < other.page_map[b].major)
{
if (passthru_left)
count++;
a++;
}
else
{
if (passthru_right)
count++;
b++;
}
}
if (passthru_left)
count += na - a;
if (passthru_right)
count += nb - b;
if (!passthru_left)
{
na = write_index;
next_page = write_index;
compact (compact_workspace, write_index);
}
if (unlikely (!resize (count)))
return;
newCount = count;
/* Process in-place backward. */
a = na;
b = nb;
for (; a && b; )
{
if (page_map[a - 1].major == other.page_map[b - 1].major)
{
a--;
b--;
count--;
page_map[count] = page_map[a];
page_at (count).v = op (page_at (a).v, other.page_at (b).v);
}
else if (page_map[a - 1].major > other.page_map[b - 1].major)
{
a--;
if (passthru_left)
{
count--;
page_map[count] = page_map[a];
}
}
else
{
b--;
if (passthru_right)
{
count--;
page_map[count].major = other.page_map[b].major;
page_map[count].index = next_page++;
page_at (count).v = other.page_at (b).v;
}
}
}
if (passthru_left)
while (a)
{
a--;
count--;
page_map[count] = page_map [a];
}
if (passthru_right)
while (b)
{
b--;
count--;
page_map[count].major = other.page_map[b].major;
page_map[count].index = next_page++;
page_at (count).v = other.page_at (b).v;
}
assert (!count);
resize (newCount);
}
template <typename Op>
static hb_bit_page_t::vector_t
op_ (const hb_bit_page_t::vector_t &a, const hb_bit_page_t::vector_t &b)
{ return Op{} (a, b); }
template <typename Op>
void process (const Op& op, const hb_bit_set_t &other)
{
process_ (op_<Op>, op (1, 0), op (0, 1), other);
}
void union_ (const hb_bit_set_t &other) { process (hb_bitwise_or, other); }
void intersect (const hb_bit_set_t &other) { process (hb_bitwise_and, other); }
void subtract (const hb_bit_set_t &other) { process (hb_bitwise_gt, other); }
void symmetric_difference (const hb_bit_set_t &other) { process (hb_bitwise_xor, other); }
bool next (hb_codepoint_t *codepoint) const
{
// TODO: this should be merged with prev() as both implementations
// are very similar.
if (unlikely (*codepoint == INVALID)) {
*codepoint = get_min ();
return *codepoint != INVALID;
}
const auto* page_map_array = page_map.arrayZ;
unsigned int major = get_major (*codepoint);
unsigned int i = last_page_lookup;
if (unlikely (i >= page_map.length || page_map_array[i].major != major))
{
page_map.bfind (major, &i, HB_NOT_FOUND_STORE_CLOSEST);
if (i >= page_map.length) {
*codepoint = INVALID;
return false;
}
}
const auto* pages_array = pages.arrayZ;
const page_map_t &current = page_map_array[i];
if (likely (current.major == major))
{
if (pages_array[current.index].next (codepoint))
{
*codepoint += current.major * page_t::PAGE_BITS;
last_page_lookup = i;
return true;
}
i++;
}
for (; i < page_map.length; i++)
{
const page_map_t &current = page_map.arrayZ[i];
hb_codepoint_t m = pages_array[current.index].get_min ();
if (m != INVALID)
{
*codepoint = current.major * page_t::PAGE_BITS + m;
last_page_lookup = i;
return true;
}
}
last_page_lookup = 0;
*codepoint = INVALID;
return false;
}
bool previous (hb_codepoint_t *codepoint) const
{
if (unlikely (*codepoint == INVALID)) {
*codepoint = get_max ();
return *codepoint != INVALID;
}
page_map_t map = {get_major (*codepoint), 0};
unsigned int i;
page_map.bfind (map, &i, HB_NOT_FOUND_STORE_CLOSEST);
if (i < page_map.length && page_map[i].major == map.major)
{
if (pages[page_map[i].index].previous (codepoint))
{
*codepoint += page_map[i].major * page_t::PAGE_BITS;
return true;
}
}
i--;
for (; (int) i >= 0; i--)
{
hb_codepoint_t m = pages[page_map[i].index].get_max ();
if (m != INVALID)
{
*codepoint = page_map[i].major * page_t::PAGE_BITS + m;
return true;
}
}
*codepoint = INVALID;
return false;
}
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;
}
/* TODO Speed up. */
*last = *first = i;
while (next (&i) && i == *last + 1)
(*last)++;
return true;
}
bool previous_range (hb_codepoint_t *first, hb_codepoint_t *last) const
{
hb_codepoint_t i;
i = *first;
if (!previous (&i))
{
*last = *first = INVALID;
return false;
}
/* TODO Speed up. */
*last = *first = i;
while (previous (&i) && i == *first - 1)
(*first)--;
return true;
}
unsigned int next_many (hb_codepoint_t codepoint,
hb_codepoint_t *out,
unsigned int size) const
{
// By default, start at the first bit of the first page of values.
unsigned int start_page = 0;
unsigned int start_page_value = 0;
if (unlikely (codepoint != INVALID))
{
const auto* page_map_array = page_map.arrayZ;
unsigned int major = get_major (codepoint);
unsigned int i = last_page_lookup;
if (unlikely (i >= page_map.length || page_map_array[i].major != major))
{
page_map.bfind (major, &i, HB_NOT_FOUND_STORE_CLOSEST);
if (i >= page_map.length)
return 0; // codepoint is greater than our max element.
}
start_page = i;
start_page_value = page_remainder (codepoint + 1);
if (unlikely (start_page_value == 0))
{
// The export-after value was last in the page. Start on next page.
start_page++;
start_page_value = 0;
}
}
unsigned int initial_size = size;
for (unsigned int i = start_page; i < page_map.length && size; i++)
{
uint32_t base = major_start (page_map[i].major);
unsigned int n = pages[page_map[i].index].write (base, start_page_value, out, size);
out += n;
size -= n;
start_page_value = 0;
}
return initial_size - size;
}
unsigned int next_many_inverted (hb_codepoint_t codepoint,
hb_codepoint_t *out,
unsigned int size) const
{
unsigned int initial_size = size;
// By default, start at the first bit of the first page of values.
unsigned int start_page = 0;
unsigned int start_page_value = 0;
if (unlikely (codepoint != INVALID))
{
const auto* page_map_array = page_map.arrayZ;
unsigned int major = get_major (codepoint);
unsigned int i = last_page_lookup;
if (unlikely (i >= page_map.length || page_map_array[i].major != major))
{
page_map.bfind(major, &i, HB_NOT_FOUND_STORE_CLOSEST);
if (unlikely (i >= page_map.length))
{
// codepoint is greater than our max element.
while (++codepoint != INVALID && size)
{
*out++ = codepoint;
size--;
}
return initial_size - size;
}
}
start_page = i;
start_page_value = page_remainder (codepoint + 1);
if (unlikely (start_page_value == 0))
{
// The export-after value was last in the page. Start on next page.
start_page++;
start_page_value = 0;
}
}
hb_codepoint_t next_value = codepoint + 1;
for (unsigned int i=start_page; i<page_map.length && size; i++)
{
uint32_t base = major_start (page_map[i].major);
unsigned int n = pages[page_map[i].index].write_inverted (base, start_page_value, out, size, &next_value);
out += n;
size -= n;
start_page_value = 0;
}
while (next_value < HB_SET_VALUE_INVALID && size) {
*out++ = next_value++;
size--;
}
return initial_size - size;
}
bool has_population () const { return population != UINT_MAX; }
unsigned int get_population () const
{
if (has_population ())
return population;
unsigned int pop = 0;
unsigned int count = pages.length;
for (unsigned int i = 0; i < count; i++)
pop += pages[i].get_population ();
population = pop;
return pop;
}
hb_codepoint_t get_min () const
{
unsigned count = pages.length;
for (unsigned i = 0; i < count; i++)
{
const auto& map = page_map[i];
const auto& page = pages[map.index];
if (!page.is_empty ())
return map.major * page_t::PAGE_BITS + page.get_min ();
}
return INVALID;
}
hb_codepoint_t get_max () const
{
unsigned count = pages.length;
for (signed i = count - 1; i >= 0; i--)
{
const auto& map = page_map[(unsigned) i];
const auto& page = pages[map.index];
if (!page.is_empty ())
return map.major * page_t::PAGE_BITS + page.get_max ();
}
return INVALID;
}
static constexpr hb_codepoint_t INVALID = page_t::INVALID;
/*
* Iterator implementation.
*/
struct iter_t : hb_iter_with_fallback_t<iter_t, hb_codepoint_t>
{
static constexpr bool is_sorted_iterator = true;
iter_t (const hb_bit_set_t &s_ = Null (hb_bit_set_t),
bool init = true) : s (&s_), v (INVALID), l(0)
{
if (init)
{
l = s->get_population () + 1;
__next__ ();
}
}
typedef hb_codepoint_t __item_t__;
hb_codepoint_t __item__ () const { return v; }
bool __more__ () const { return v != INVALID; }
void __next__ () { s->next (&v); if (l) l--; }
void __prev__ () { s->previous (&v); }
unsigned __len__ () const { return l; }
iter_t end () const { return iter_t (*s, false); }
bool operator != (const iter_t& o) const
{ return s != o.s || v != o.v; }
protected:
const hb_bit_set_t *s;
hb_codepoint_t v;
unsigned l;
};
iter_t iter () const { return iter_t (*this); }
operator iter_t () const { return iter (); }
protected:
page_t *page_for (hb_codepoint_t g, bool insert = false)
{
unsigned major = get_major (g);
/* The extra page_map length is necessary; can't just rely on vector here,
* since the next check would be tricked because a null page also has
* major==0, which we can't distinguish from an actualy major==0 page... */
unsigned i = last_page_lookup;
if (likely (i < page_map.length))
{
auto &cached_page = page_map.arrayZ[i];
if (cached_page.major == major)
return &pages[cached_page.index];
}
page_map_t map = {major, pages.length};
if (!page_map.bfind (map, &i, HB_NOT_FOUND_STORE_CLOSEST))
{
if (!insert)
return nullptr;
if (unlikely (!resize (pages.length + 1)))
return nullptr;
pages[map.index].init0 ();
memmove (page_map + i + 1,
page_map + i,
(page_map.length - 1 - i) * page_map.item_size);
page_map[i] = map;
}
last_page_lookup = i;
return &pages[page_map[i].index];
}
const page_t *page_for (hb_codepoint_t g) const
{
unsigned major = get_major (g);
/* The extra page_map length is necessary; can't just rely on vector here,
* since the next check would be tricked because a null page also has
* major==0, which we can't distinguish from an actualy major==0 page... */
unsigned i = last_page_lookup;
if (likely (i < page_map.length))
{
auto &cached_page = page_map.arrayZ[i];
if (cached_page.major == major)
return &pages[cached_page.index];
}
page_map_t key = {major};
if (!page_map.bfind (key, &i))
return nullptr;
last_page_lookup = i;
return &pages[page_map[i].index];
}
page_t &page_at (unsigned int i) { return pages[page_map[i].index]; }
const page_t &page_at (unsigned int i) const { return pages[page_map[i].index]; }
unsigned int get_major (hb_codepoint_t g) const { return g >> page_t::PAGE_BITS_LOG_2; }
unsigned int page_remainder (hb_codepoint_t g) const { return g & page_t::PAGE_BITMASK; }
hb_codepoint_t major_start (unsigned int major) const { return major << page_t::PAGE_BITS_LOG_2; }
};
#endif /* HB_BIT_SET_HH */
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