src/hb-bit-set.hh - third_party/harfbuzz - Git at Google

 /*
  * 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 unsigned int 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 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 (); }

   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 (!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 = (const T *) ((const char *) 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;

     /* TODO switch to vector operator =. */
     hb_memcpy ((void *) pages, (const void *) other.pages, count * pages.item_size);
     hb_memcpy ((void *) page_map, (const void *) other.page_map, count * page_map.item_size);
   }

   bool is_equal (const hb_bit_set_t &other) const
   {
     if (has_population () && other.has_population () &&
 	get_population () != other.get_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 () &&
 	get_population () != larger_set.get_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:

   template <typename Op>
   void process (const Op& op, const hb_bit_set_t &other)
   {
     const bool passthru_left = op (1, 0);
     const bool passthru_right = op (0, 1);

     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);
   }

   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;
   }

   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)
   {
     page_map_t map = {get_major (g), pages.length};
     unsigned int i;
     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;
     }
     return &pages[page_map[i].index];
   }
   const page_t *page_for (hb_codepoint_t g) const
   {
     page_map_t key = {get_major (g)};
     const page_map_t *found = page_map.bsearch (key);
     if (found)
       return &pages[found->index];
     return nullptr;
   }
   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; }
   hb_codepoint_t major_start (unsigned int major) const { return major * page_t::PAGE_BITS; }
 };


 #endif /* HB_BIT_SET_HH */
	/*
	* 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 unsigned int 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 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 (); }

	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 (!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 = (const T ) ((const char ) 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;

	/* TODO switch to vector operator =. */
	hb_memcpy ((void ) pages, (const void ) other.pages, count * pages.item_size);
	hb_memcpy ((void ) page_map, (const void ) other.page_map, count * page_map.item_size);
	}

	bool is_equal (const hb_bit_set_t &other) const
	{
	if (has_population () && other.has_population () &&
	get_population () != other.get_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 () &&
	get_population () != larger_set.get_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:

	template <typename Op>
	void process (const Op& op, const hb_bit_set_t &other)
	{
	const bool passthru_left = op (1, 0);
	const bool passthru_right = op (0, 1);

	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);
	}

	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;
	}

	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)
	{
	page_map_t map = {get_major (g), pages.length};
	unsigned int i;
	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;
	}
	return &pages[page_map[i].index];
	}
	const page_t *page_for (hb_codepoint_t g) const
	{
	page_map_t key = {get_major (g)};
	const page_map_t *found = page_map.bsearch (key);
	if (found)
	return &pages[found->index];
	return nullptr;
	}
	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; }
	hb_codepoint_t major_start (unsigned int major) const { return major * page_t::PAGE_BITS; }
	};


	#endif /* HB_BIT_SET_HH */