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

 /*
  * 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_SET_HH
 #define HB_SET_HH

 #include "hb.hh"


 /*
  * hb_set_t
  */

 /* TODO Keep a free-list so we can free pages that are completely zeroed.  At that
  * point maybe also use a sentinel value for "all-1" pages? */

 struct hb_set_t
 {
   struct page_map_t
   {
     inline int cmp (const page_map_t *o) const { return (int) o->major - (int) major; }

     uint32_t major;
     uint32_t index;
   };

   struct page_t
   {
     inline void init0 (void) { memset (&v, 0, sizeof (v)); }
     inline void init1 (void) { memset (&v, 0xff, sizeof (v)); }

     inline unsigned int len (void) const
     { return ARRAY_LENGTH_CONST (v); }

     inline bool is_empty (void) const
     {
       for (unsigned int i = 0; i < len (); i++)
         if (v[i])
 	  return false;
       return true;
     }

     inline void add (hb_codepoint_t g) { elt (g) |= mask (g); }
     inline void del (hb_codepoint_t g) { elt (g) &= ~mask (g); }
     inline bool has (hb_codepoint_t g) const { return !!(elt (g) & mask (g)); }

     inline void add_range (hb_codepoint_t a, hb_codepoint_t b)
     {
       elt_t *la = &elt (a);
       elt_t *lb = &elt (b);
       if (la == lb)
         *la |= (mask (b) << 1) - mask(a);
       else
       {
 	*la |= ~(mask (a) - 1);
 	la++;

 	memset (la, 0xff, (char *) lb - (char *) la);

 	*lb |= ((mask (b) << 1) - 1);
       }
     }

     inline bool is_equal (const page_t *other) const
     {
       return 0 == memcmp (&v, &other->v, sizeof (v));
     }

     inline unsigned int get_population (void) const
     {
       unsigned int pop = 0;
       for (unsigned int i = 0; i < len (); i++)
         pop += hb_popcount (v[i]);
       return pop;
     }

     inline bool next (hb_codepoint_t *codepoint) const
     {
       unsigned int m = (*codepoint + 1) & MASK;
       if (!m)
       {
 	*codepoint = INVALID;
 	return false;
       }
       unsigned int i = m / ELT_BITS;
       unsigned int j = m & ELT_MASK;

       const elt_t vv = v[i] & ~((elt_t (1) << j) - 1);
       for (const elt_t *p = &vv; i < len (); p = &v[++i])
 	if (*p)
 	{
 	  *codepoint = i * ELT_BITS + elt_get_min (*p);
 	  return true;
 	}

       *codepoint = INVALID;
       return false;
     }
     inline bool previous (hb_codepoint_t *codepoint) const
     {
       unsigned int m = (*codepoint - 1) & MASK;
       if (m == MASK)
       {
 	*codepoint = INVALID;
 	return false;
       }
       unsigned int i = m / ELT_BITS;
       unsigned int j = m & ELT_MASK;

       const elt_t vv = v[i] & ((elt_t (1) << (j + 1)) - 1);
       for (const elt_t *p = &vv; (int) i >= 0; p = &v[--i])
 	if (*p)
 	{
 	  *codepoint = i * ELT_BITS + elt_get_max (*p);
 	  return true;
 	}

       *codepoint = INVALID;
       return false;
     }
     inline hb_codepoint_t get_min (void) const
     {
       for (unsigned int i = 0; i < len (); i++)
         if (v[i])
 	  return i * ELT_BITS + elt_get_min (v[i]);
       return INVALID;
     }
     inline hb_codepoint_t get_max (void) const
     {
       for (int i = len () - 1; i >= 0; i--)
         if (v[i])
 	  return i * ELT_BITS + elt_get_max (v[i]);
       return 0;
     }

     typedef unsigned long long elt_t;
     enum { PAGE_BITS = 512 };
     static_assert ((PAGE_BITS & ((PAGE_BITS) - 1)) == 0, "");

     static inline unsigned int elt_get_min (const elt_t &elt) { return hb_ctz (elt); }
     static inline unsigned int elt_get_max (const elt_t &elt) { return hb_bit_storage (elt) - 1; }

     typedef hb_vector_size_t<elt_t, PAGE_BITS / 8> vector_t;

     enum { ELT_BITS = sizeof (elt_t) * 8 };
     enum { ELT_MASK = ELT_BITS - 1 };
     enum { BITS = sizeof (vector_t) * 8 };
     enum { MASK = BITS - 1 };
     static_assert ((unsigned) PAGE_BITS == (unsigned) BITS, "");

     elt_t &elt (hb_codepoint_t g) { return v[(g & MASK) / ELT_BITS]; }
     elt_t const &elt (hb_codepoint_t g) const { return v[(g & MASK) / ELT_BITS]; }
     elt_t mask (hb_codepoint_t g) const { return elt_t (1) << (g & ELT_MASK); }

     vector_t v;
   };
   static_assert (page_t::PAGE_BITS == sizeof (page_t) * 8, "");

   hb_object_header_t header;
   bool successful; /* Allocations successful */
   mutable unsigned int population;
   hb_vector_t<page_map_t, 1> page_map;
   hb_vector_t<page_t, 1> pages;

   inline void init_shallow (void)
   {
     successful = true;
     population = 0;
     page_map.init ();
     pages.init ();
   }
   inline void init (void)
   {
     hb_object_init (this);
     init_shallow ();
   }
   inline void fini_shallow (void)
   {
     page_map.fini ();
     pages.fini ();
   }
   inline void fini (void)
   {
     hb_object_fini (this);
     fini_shallow ();
   }

   inline bool resize (unsigned int count)
   {
     if (unlikely (!successful)) return false;
     if (!pages.resize (count) || !page_map.resize (count))
     {
       pages.resize (page_map.len);
       successful = false;
       return false;
     }
     return true;
   }

   inline void clear (void) {
     if (unlikely (hb_object_is_inert (this)))
       return;
     successful = true;
     population = 0;
     page_map.resize (0);
     pages.resize (0);
   }
   inline bool is_empty (void) const {
     unsigned int count = pages.len;
     for (unsigned int i = 0; i < count; i++)
       if (!pages[i].is_empty ())
         return false;
     return true;
   }

   inline void dirty (void) { population = (unsigned int) -1; }

   inline void add (hb_codepoint_t g)
   {
     if (unlikely (!successful)) return;
     if (unlikely (g == INVALID)) return;
     dirty ();
     page_t *page = page_for_insert (g); if (unlikely (!page)) return;
     page->add (g);
   }
   inline 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_insert (a); if (unlikely (!page)) return false;
       page->add_range (a, b);
     }
     else
     {
       page_t *page = page_for_insert (a); 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_insert (major_start (m)); if (unlikely (!page)) return false;
 	page->init1 ();
       }

       page = page_for_insert (b); if (unlikely (!page)) return false;
       page->add_range (major_start (mb), b);
     }
     return true;
   }

   template <typename T>
   inline void add_array (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_insert (g); if (unlikely (!page)) return;
       unsigned int start = major_start (m);
       unsigned int end = major_start (m + 1);
       do
       {
 	page->add (g);

 	array = (const T *) ((const char *) array + stride);
 	count--;
       }
       while (count && (g = *array, start <= g && g < end));
     }
   }

   /* Might return false if array looks unsorted.
    * Used for faster rejection of corrupt data. */
   template <typename T>
   inline bool add_sorted_array (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_insert (g); if (unlikely (!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;
 	page->add (g);

 	array = (const T *) ((const char *) array + stride);
 	count--;
       }
       while (count && (g = *array, g < end));
     }
     return true;
   }

   inline void del (hb_codepoint_t g)
   {
     /* TODO perform op even if !successful. */
     if (unlikely (!successful)) return;
     page_t *p = page_for (g);
     if (!p)
       return;
     dirty ();
     p->del (g);
   }
   inline void del_range (hb_codepoint_t a, hb_codepoint_t b)
   {
     /* TODO perform op even if !successful. */
     /* TODO Optimize, like add_range(). */
     if (unlikely (!successful)) return;
     for (unsigned int i = a; i < b + 1; i++)
       del (i);
   }
   inline bool has (hb_codepoint_t g) const
   {
     const page_t *p = page_for (g);
     if (!p)
       return false;
     return p->has (g);
   }
   inline bool intersects (hb_codepoint_t first,
 			  hb_codepoint_t last) const
   {
     hb_codepoint_t c = first - 1;
     return next (&c) && c <= last;
   }
   inline void set (const hb_set_t *other)
   {
     if (unlikely (!successful)) return;
     unsigned int count = other->pages.len;
     if (!resize (count))
       return;
     population = other->population;
     memcpy (pages.arrayZ(), other->pages.arrayZ(), count * sizeof (pages.arrayZ()[0]));
     memcpy (page_map.arrayZ(), other->page_map.arrayZ(), count * sizeof (page_map.arrayZ()[0]));
   }

   inline bool is_equal (const hb_set_t *other) const
   {
     if (get_population () != other->get_population ())
       return false;

     unsigned int na = pages.len;
     unsigned int nb = other->pages.len;

     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;
   }

   inline bool is_subset (const hb_set_t *larger_set) const
   {
     if (get_population () > larger_set->get_population ())
       return false;

     /* TODO Optimize to use pages. */
     hb_codepoint_t c = INVALID;
     while (next (&c))
       if (!larger_set->has (c))
         return false;

     return true;
   }

   template <class Op>
   inline void process (const hb_set_t *other)
   {
     if (unlikely (!successful)) return;

     dirty ();

     unsigned int na = pages.len;
     unsigned int nb = other->pages.len;
     unsigned int next_page = na;

     unsigned int count = 0, newCount = 0;
     unsigned int a = 0, b = 0;
     for (; a < na && b < nb; )
     {
       if (page_map[a].major == other->page_map[b].major)
       {
         count++;
 	a++;
 	b++;
       }
       else if (page_map[a].major < other->page_map[b].major)
       {
         if (Op::passthru_left)
 	  count++;
         a++;
       }
       else
       {
         if (Op::passthru_right)
 	  count++;
         b++;
       }
     }
     if (Op::passthru_left)
       count += na - a;
     if (Op::passthru_right)
       count += nb - b;

     if (count > pages.len)
       if (!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];
 	Op::process (page_at (count).v, page_at (a).v, other->page_at (b).v);
       }
       else if (page_map[a - 1].major > other->page_map[b - 1].major)
       {
 	a--;
 	if (Op::passthru_left)
 	{
 	  count--;
 	  page_map[count] = page_map[a];
 	}
       }
       else
       {
 	b--;
 	if (Op::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 (Op::passthru_left)
       while (a)
       {
 	a--;
 	count--;
 	page_map[count] = page_map [a];
       }
     if (Op::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);
     if (pages.len > newCount)
       resize (newCount);
   }

   inline void union_ (const hb_set_t *other)
   {
     process<HbOpOr> (other);
   }
   inline void intersect (const hb_set_t *other)
   {
     process<HbOpAnd> (other);
   }
   inline void subtract (const hb_set_t *other)
   {
     process<HbOpMinus> (other);
   }
   inline void symmetric_difference (const hb_set_t *other)
   {
     process<HbOpXor> (other);
   }
   inline bool next (hb_codepoint_t *codepoint) const
   {
     if (unlikely (*codepoint == INVALID)) {
       *codepoint = get_min ();
       return *codepoint != INVALID;
     }

     page_map_t map = {get_major (*codepoint), 0};
     unsigned int i;
     page_map.bfind (map, &i);
     if (i < page_map.len && page_map[i].major == map.major)
     {
       if (pages[page_map[i].index].next (codepoint))
       {
 	*codepoint += page_map[i].major * page_t::PAGE_BITS;
 	return true;
       }
       i++;
     }
     for (; i < page_map.len; i++)
     {
       hb_codepoint_t m = pages[page_map[i].index].get_min ();
       if (m != INVALID)
       {
 	*codepoint = page_map[i].major * page_t::PAGE_BITS + m;
 	return true;
       }
     }
     *codepoint = INVALID;
     return false;
   }
   inline 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);
     if (i < page_map.len && 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;
   }
   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;
     }

     /* TODO Speed up. */
     *last = *first = i;
     while (next (&i) && i == *last + 1)
       (*last)++;

     return true;
   }
   inline 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;
   }

   inline unsigned int get_population (void) const
   {
     if (population != (unsigned int) -1)
       return population;

     unsigned int pop = 0;
     unsigned int count = pages.len;
     for (unsigned int i = 0; i < count; i++)
       pop += pages[i].get_population ();

     population = pop;
     return pop;
   }
   inline hb_codepoint_t get_min (void) const
   {
     unsigned int count = pages.len;
     for (unsigned int i = 0; i < count; i++)
       if (!page_at (i).is_empty ())
         return page_map[i].major * page_t::PAGE_BITS + page_at (i).get_min ();
     return INVALID;
   }
   inline hb_codepoint_t get_max (void) const
   {
     unsigned int count = pages.len;
     for (int i = count - 1; i >= 0; i++)
       if (!page_at (i).is_empty ())
         return page_map[i].major * page_t::PAGE_BITS + page_at (i).get_max ();
     return INVALID;
   }

   static  const hb_codepoint_t INVALID = HB_SET_VALUE_INVALID;

   inline page_t *page_for_insert (hb_codepoint_t g)
   {
     page_map_t map = {get_major (g), pages.len};
     unsigned int i;
     if (!page_map.bfind (map, &i))
     {
       if (!resize (pages.len + 1))
 	return nullptr;

       pages[map.index].init0 ();
       memmove (&page_map[i + 1], &page_map[i], (page_map.len - 1 - i) * sizeof (page_map[0]));
       page_map[i] = map;
     }
     return &pages[page_map[i].index];
   }
   inline page_t *page_for (hb_codepoint_t g)
   {
     page_map_t key = {get_major (g)};
     const page_map_t *found = page_map.bsearch (key);
     if (found)
       return &pages[found->index];
     return nullptr;
   }
   inline 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;
   }
   inline page_t &page_at (unsigned int i) { return pages[page_map[i].index]; }
   inline const page_t &page_at (unsigned int i) const { return pages[page_map[i].index]; }
   inline unsigned int get_major (hb_codepoint_t g) const { return g / page_t::PAGE_BITS; }
   inline hb_codepoint_t major_start (unsigned int major) const { return major * page_t::PAGE_BITS; }
 };


 #endif /* HB_SET_HH */
	/*
	* 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_SET_HH
	#define HB_SET_HH

	#include "hb.hh"


	/*
	* hb_set_t
	*/

	/* TODO Keep a free-list so we can free pages that are completely zeroed. At that
	* point maybe also use a sentinel value for "all-1" pages? */

	struct hb_set_t
	{
	struct page_map_t
	{
	inline int cmp (const page_map_t *o) const { return (int) o->major - (int) major; }

	uint32_t major;
	uint32_t index;
	};

	struct page_t
	{
	inline void init0 (void) { memset (&v, 0, sizeof (v)); }
	inline void init1 (void) { memset (&v, 0xff, sizeof (v)); }

	inline unsigned int len (void) const
	{ return ARRAY_LENGTH_CONST (v); }

	inline bool is_empty (void) const
	{
	for (unsigned int i = 0; i < len (); i++)
	if (v[i])
	return false;
	return true;
	}

	inline void add (hb_codepoint_t g) { elt (g) \|= mask (g); }
	inline void del (hb_codepoint_t g) { elt (g) &= ~mask (g); }
	inline bool has (hb_codepoint_t g) const { return !!(elt (g) & mask (g)); }

	inline void add_range (hb_codepoint_t a, hb_codepoint_t b)
	{
	elt_t *la = &elt (a);
	elt_t *lb = &elt (b);
	if (la == lb)
	*la \|= (mask (b) << 1) - mask(a);
	else
	{
	*la \|= ~(mask (a) - 1);
	la++;

	memset (la, 0xff, (char ) lb - (char ) la);

	*lb \|= ((mask (b) << 1) - 1);
	}
	}

	inline bool is_equal (const page_t *other) const
	{
	return 0 == memcmp (&v, &other->v, sizeof (v));
	}

	inline unsigned int get_population (void) const
	{
	unsigned int pop = 0;
	for (unsigned int i = 0; i < len (); i++)
	pop += hb_popcount (v[i]);
	return pop;
	}

	inline bool next (hb_codepoint_t *codepoint) const
	{
	unsigned int m = (*codepoint + 1) & MASK;
	if (!m)
	{
	*codepoint = INVALID;
	return false;
	}
	unsigned int i = m / ELT_BITS;
	unsigned int j = m & ELT_MASK;

	const elt_t vv = v[i] & ~((elt_t (1) << j) - 1);
	for (const elt_t *p = &vv; i < len (); p = &v[++i])
	if (*p)
	{
	codepoint = i ELT_BITS + elt_get_min (*p);
	return true;
	}

	*codepoint = INVALID;
	return false;
	}
	inline bool previous (hb_codepoint_t *codepoint) const
	{
	unsigned int m = (*codepoint - 1) & MASK;
	if (m == MASK)
	{
	*codepoint = INVALID;
	return false;
	}
	unsigned int i = m / ELT_BITS;
	unsigned int j = m & ELT_MASK;

	const elt_t vv = v[i] & ((elt_t (1) << (j + 1)) - 1);
	for (const elt_t *p = &vv; (int) i >= 0; p = &v[--i])
	if (*p)
	{
	codepoint = i ELT_BITS + elt_get_max (*p);
	return true;
	}

	*codepoint = INVALID;
	return false;
	}
	inline hb_codepoint_t get_min (void) const
	{
	for (unsigned int i = 0; i < len (); i++)
	if (v[i])
	return i * ELT_BITS + elt_get_min (v[i]);
	return INVALID;
	}
	inline hb_codepoint_t get_max (void) const
	{
	for (int i = len () - 1; i >= 0; i--)
	if (v[i])
	return i * ELT_BITS + elt_get_max (v[i]);
	return 0;
	}

	typedef unsigned long long elt_t;
	enum { PAGE_BITS = 512 };
	static_assert ((PAGE_BITS & ((PAGE_BITS) - 1)) == 0, "");

	static inline unsigned int elt_get_min (const elt_t &elt) { return hb_ctz (elt); }
	static inline unsigned int elt_get_max (const elt_t &elt) { return hb_bit_storage (elt) - 1; }

	typedef hb_vector_size_t<elt_t, PAGE_BITS / 8> vector_t;

	enum { ELT_BITS = sizeof (elt_t) * 8 };
	enum { ELT_MASK = ELT_BITS - 1 };
	enum { BITS = sizeof (vector_t) * 8 };
	enum { MASK = BITS - 1 };
	static_assert ((unsigned) PAGE_BITS == (unsigned) BITS, "");

	elt_t &elt (hb_codepoint_t g) { return v[(g & MASK) / ELT_BITS]; }
	elt_t const &elt (hb_codepoint_t g) const { return v[(g & MASK) / ELT_BITS]; }
	elt_t mask (hb_codepoint_t g) const { return elt_t (1) << (g & ELT_MASK); }

	vector_t v;
	};
	static_assert (page_t::PAGE_BITS == sizeof (page_t) * 8, "");

	hb_object_header_t header;
	bool successful; /* Allocations successful */
	mutable unsigned int population;
	hb_vector_t<page_map_t, 1> page_map;
	hb_vector_t<page_t, 1> pages;

	inline void init_shallow (void)
	{
	successful = true;
	population = 0;
	page_map.init ();
	pages.init ();
	}
	inline void init (void)
	{
	hb_object_init (this);
	init_shallow ();
	}
	inline void fini_shallow (void)
	{
	page_map.fini ();
	pages.fini ();
	}
	inline void fini (void)
	{
	hb_object_fini (this);
	fini_shallow ();
	}

	inline bool resize (unsigned int count)
	{
	if (unlikely (!successful)) return false;
	if (!pages.resize (count) \|\| !page_map.resize (count))
	{
	pages.resize (page_map.len);
	successful = false;
	return false;
	}
	return true;
	}

	inline void clear (void) {
	if (unlikely (hb_object_is_inert (this)))
	return;
	successful = true;
	population = 0;
	page_map.resize (0);
	pages.resize (0);
	}
	inline bool is_empty (void) const {
	unsigned int count = pages.len;
	for (unsigned int i = 0; i < count; i++)
	if (!pages[i].is_empty ())
	return false;
	return true;
	}

	inline void dirty (void) { population = (unsigned int) -1; }

	inline void add (hb_codepoint_t g)
	{
	if (unlikely (!successful)) return;
	if (unlikely (g == INVALID)) return;
	dirty ();
	page_t *page = page_for_insert (g); if (unlikely (!page)) return;
	page->add (g);
	}
	inline 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_insert (a); if (unlikely (!page)) return false;
	page->add_range (a, b);
	}
	else
	{
	page_t *page = page_for_insert (a); 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_insert (major_start (m)); if (unlikely (!page)) return false;
	page->init1 ();
	}

	page = page_for_insert (b); if (unlikely (!page)) return false;
	page->add_range (major_start (mb), b);
	}
	return true;
	}

	template <typename T>
	inline void add_array (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_insert (g); if (unlikely (!page)) return;
	unsigned int start = major_start (m);
	unsigned int end = major_start (m + 1);
	do
	{
	page->add (g);

	array = (const T ) ((const char ) array + stride);
	count--;
	}
	while (count && (g = *array, start <= g && g < end));
	}
	}

	/* Might return false if array looks unsorted.
	* Used for faster rejection of corrupt data. */
	template <typename T>
	inline bool add_sorted_array (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_insert (g); if (unlikely (!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;
	page->add (g);

	array = (const T ) ((const char ) array + stride);
	count--;
	}
	while (count && (g = *array, g < end));
	}
	return true;
	}

	inline void del (hb_codepoint_t g)
	{
	/* TODO perform op even if !successful. */
	if (unlikely (!successful)) return;
	page_t *p = page_for (g);
	if (!p)
	return;
	dirty ();
	p->del (g);
	}
	inline void del_range (hb_codepoint_t a, hb_codepoint_t b)
	{
	/* TODO perform op even if !successful. */
	/* TODO Optimize, like add_range(). */
	if (unlikely (!successful)) return;
	for (unsigned int i = a; i < b + 1; i++)
	del (i);
	}
	inline bool has (hb_codepoint_t g) const
	{
	const page_t *p = page_for (g);
	if (!p)
	return false;
	return p->has (g);
	}
	inline bool intersects (hb_codepoint_t first,
	hb_codepoint_t last) const
	{
	hb_codepoint_t c = first - 1;
	return next (&c) && c <= last;
	}
	inline void set (const hb_set_t *other)
	{
	if (unlikely (!successful)) return;
	unsigned int count = other->pages.len;
	if (!resize (count))
	return;
	population = other->population;
	memcpy (pages.arrayZ(), other->pages.arrayZ(), count * sizeof (pages.arrayZ()[0]));
	memcpy (page_map.arrayZ(), other->page_map.arrayZ(), count * sizeof (page_map.arrayZ()[0]));
	}

	inline bool is_equal (const hb_set_t *other) const
	{
	if (get_population () != other->get_population ())
	return false;

	unsigned int na = pages.len;
	unsigned int nb = other->pages.len;

	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;
	}

	inline bool is_subset (const hb_set_t *larger_set) const
	{
	if (get_population () > larger_set->get_population ())
	return false;

	/* TODO Optimize to use pages. */
	hb_codepoint_t c = INVALID;
	while (next (&c))
	if (!larger_set->has (c))
	return false;

	return true;
	}

	template <class Op>
	inline void process (const hb_set_t *other)
	{
	if (unlikely (!successful)) return;

	dirty ();

	unsigned int na = pages.len;
	unsigned int nb = other->pages.len;
	unsigned int next_page = na;

	unsigned int count = 0, newCount = 0;
	unsigned int a = 0, b = 0;
	for (; a < na && b < nb; )
	{
	if (page_map[a].major == other->page_map[b].major)
	{
	count++;
	a++;
	b++;
	}
	else if (page_map[a].major < other->page_map[b].major)
	{
	if (Op::passthru_left)
	count++;
	a++;
	}
	else
	{
	if (Op::passthru_right)
	count++;
	b++;
	}
	}
	if (Op::passthru_left)
	count += na - a;
	if (Op::passthru_right)
	count += nb - b;

	if (count > pages.len)
	if (!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];
	Op::process (page_at (count).v, page_at (a).v, other->page_at (b).v);
	}
	else if (page_map[a - 1].major > other->page_map[b - 1].major)
	{
	a--;
	if (Op::passthru_left)
	{
	count--;
	page_map[count] = page_map[a];
	}
	}
	else
	{
	b--;
	if (Op::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 (Op::passthru_left)
	while (a)
	{
	a--;
	count--;
	page_map[count] = page_map [a];
	}
	if (Op::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);
	if (pages.len > newCount)
	resize (newCount);
	}

	inline void union_ (const hb_set_t *other)
	{
	process<HbOpOr> (other);
	}
	inline void intersect (const hb_set_t *other)
	{
	process<HbOpAnd> (other);
	}
	inline void subtract (const hb_set_t *other)
	{
	process<HbOpMinus> (other);
	}
	inline void symmetric_difference (const hb_set_t *other)
	{
	process<HbOpXor> (other);
	}
	inline bool next (hb_codepoint_t *codepoint) const
	{
	if (unlikely (*codepoint == INVALID)) {
	*codepoint = get_min ();
	return *codepoint != INVALID;
	}

	page_map_t map = {get_major (*codepoint), 0};
	unsigned int i;
	page_map.bfind (map, &i);
	if (i < page_map.len && page_map[i].major == map.major)
	{
	if (pages[page_map[i].index].next (codepoint))
	{
	codepoint += page_map[i].major page_t::PAGE_BITS;
	return true;
	}
	i++;
	}
	for (; i < page_map.len; i++)
	{
	hb_codepoint_t m = pages[page_map[i].index].get_min ();
	if (m != INVALID)
	{
	codepoint = page_map[i].major page_t::PAGE_BITS + m;
	return true;
	}
	}
	*codepoint = INVALID;
	return false;
	}
	inline 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);
	if (i < page_map.len && 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;
	}
	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;
	}

	/* TODO Speed up. */
	last = first = i;
	while (next (&i) && i == *last + 1)
	(*last)++;

	return true;
	}
	inline 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;
	}

	inline unsigned int get_population (void) const
	{
	if (population != (unsigned int) -1)
	return population;

	unsigned int pop = 0;
	unsigned int count = pages.len;
	for (unsigned int i = 0; i < count; i++)
	pop += pages[i].get_population ();

	population = pop;
	return pop;
	}
	inline hb_codepoint_t get_min (void) const
	{
	unsigned int count = pages.len;
	for (unsigned int i = 0; i < count; i++)
	if (!page_at (i).is_empty ())
	return page_map[i].major * page_t::PAGE_BITS + page_at (i).get_min ();
	return INVALID;
	}
	inline hb_codepoint_t get_max (void) const
	{
	unsigned int count = pages.len;
	for (int i = count - 1; i >= 0; i++)
	if (!page_at (i).is_empty ())
	return page_map[i].major * page_t::PAGE_BITS + page_at (i).get_max ();
	return INVALID;
	}

	static const hb_codepoint_t INVALID = HB_SET_VALUE_INVALID;

	inline page_t *page_for_insert (hb_codepoint_t g)
	{
	page_map_t map = {get_major (g), pages.len};
	unsigned int i;
	if (!page_map.bfind (map, &i))
	{
	if (!resize (pages.len + 1))
	return nullptr;

	pages[map.index].init0 ();
	memmove (&page_map[i + 1], &page_map[i], (page_map.len - 1 - i) * sizeof (page_map[0]));
	page_map[i] = map;
	}
	return &pages[page_map[i].index];
	}
	inline page_t *page_for (hb_codepoint_t g)
	{
	page_map_t key = {get_major (g)};
	const page_map_t *found = page_map.bsearch (key);
	if (found)
	return &pages[found->index];
	return nullptr;
	}
	inline 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;
	}
	inline page_t &page_at (unsigned int i) { return pages[page_map[i].index]; }
	inline const page_t &page_at (unsigned int i) const { return pages[page_map[i].index]; }
	inline unsigned int get_major (hb_codepoint_t g) const { return g / page_t::PAGE_BITS; }
	inline hb_codepoint_t major_start (unsigned int major) const { return major * page_t::PAGE_BITS; }
	};


	#endif /* HB_SET_HH */