1 files changed, 411 insertions, 236 deletions

diff --git a/src/3rdparty/harfbuzz-ng/src/hb-set-private.hh b/src/3rdparty/harfbuzz-ng/src/hb-set-private.hh
index e2010d7626..9c6f3ee37a 100644
--- a/src/3rdparty/harfbuzz-ng/src/hb-set-private.hh
+++ b/src/3rdparty/harfbuzz-ng/src/hb-set-private.hh
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2012  Google, Inc.
+ * Copyright © 2012,2017  Google, Inc.
  *
  *  This is part of HarfBuzz, a text shaping library.
  *
@@ -32,254 +32,462 @@
 
 
 /*
- * The set digests here implement various "filters" that support
- * "approximate member query".  Conceptually these are like Bloom
- * Filter and Quotient Filter, however, much smaller, faster, and
- * designed to fit the requirements of our uses for glyph coverage
- * queries.
- *
- * Our filters are highly accurate if the lookup covers fairly local
- * set of glyphs, but fully flooded and ineffective if coverage is
- * all over the place.
- *
- * The frozen-set can be used instead of a digest, to trade more
- * memory for 100% accuracy, but in practice, that doesn't look like
- * an attractive trade-off.
+ * hb_set_t
  */
 
-template <typename mask_t, unsigned int shift>
-struct hb_set_digest_lowest_bits_t
-{
-  ASSERT_POD ();
-
-  static const unsigned int mask_bytes = sizeof (mask_t);
-  static const unsigned int mask_bits = sizeof (mask_t) * 8;
-  static const unsigned int num_bits = 0
-				     + (mask_bytes >= 1 ? 3 : 0)
-				     + (mask_bytes >= 2 ? 1 : 0)
-				     + (mask_bytes >= 4 ? 1 : 0)
-				     + (mask_bytes >= 8 ? 1 : 0)
-				     + (mask_bytes >= 16? 1 : 0)
-				     + 0;
-
-  ASSERT_STATIC (shift < sizeof (hb_codepoint_t) * 8);
-  ASSERT_STATIC (shift + num_bits <= sizeof (hb_codepoint_t) * 8);
-
-  inline void init (void) {
-    mask = 0;
-  }
+/* 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? */
 
-  inline void add (hb_codepoint_t g) {
-    mask |= mask_for (g);
-  }
-
-  inline void add_range (hb_codepoint_t a, hb_codepoint_t b) {
-    if ((b >> shift) - (a >> shift) >= mask_bits - 1)
-      mask = (mask_t) -1;
-    else {
-      mask_t ma = mask_for (a);
-      mask_t mb = mask_for (b);
-      mask |= mb + (mb - ma) - (mb < ma);
-    }
-  }
+struct hb_set_t
+{
+  struct page_map_t
+  {
+    inline int cmp (const page_map_t *o) const { return (int) o->major - (int) major; }
 
-  inline bool may_have (hb_codepoint_t g) const {
-    return !!(mask & mask_for (g));
-  }
+    uint32_t major;
+    uint32_t index;
+  };
 
-  private:
+  struct page_t
+  {
+    inline void init0 (void) { memset (&v, 0, sizeof (v)); }
+    inline void init1 (void) { memset (&v, 0xff, sizeof (v)); }
 
-  static inline mask_t mask_for (hb_codepoint_t g) {
-    return ((mask_t) 1) << ((g >> shift) & (mask_bits - 1));
-  }
-  mask_t mask;
-};
+    inline unsigned int len (void) const
+    { return ARRAY_LENGTH_CONST (v); }
 
-template <typename head_t, typename tail_t>
-struct hb_set_digest_combiner_t
-{
-  ASSERT_POD ();
-
-  inline void init (void) {
-    head.init ();
-    tail.init ();
-  }
+    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) {
-    head.add (g);
-    tail.add (g);
-  }
+    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) {
-    head.add_range (a, b);
-    tail.add_range (a, b);
-  }
+    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 may_have (hb_codepoint_t g) const {
-    return head.may_have (g) && tail.may_have (g);
-  }
+    inline bool is_equal (const page_t *other) const
+    {
+      return 0 == memcmp (&v, &other->v, sizeof (v));
+    }
 
-  private:
-  head_t head;
-  tail_t tail;
-};
+    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;
+
+      for (; j < ELT_BITS; j++)
+        if (v[i] & (elt_t (1) << j))
+	  goto found;
+      for (i++; i < len (); i++)
+        if (v[i])
+	  for (j = 0; j < ELT_BITS; j++)
+	    if (v[i] & (elt_t (1) << j))
+	      goto found;
+
+      *codepoint = INVALID;
+      return false;
 
-/*
- * hb_set_digest_t
- *
- * This is a combination of digests that performs "best".
- * There is not much science to this: it's a result of intuition
- * and testing.
- */
-typedef hb_set_digest_combiner_t
-<
-  hb_set_digest_lowest_bits_t<unsigned long, 4>,
-  hb_set_digest_combiner_t
-  <
-    hb_set_digest_lowest_bits_t<unsigned long, 0>,
-    hb_set_digest_lowest_bits_t<unsigned long, 9>
-  >
-> hb_set_digest_t;
+    found:
+      *codepoint = i * ELT_BITS + j;
+      return true;
+    }
+    inline hb_codepoint_t get_min (void) const
+    {
+      for (unsigned int i = 0; i < len (); i++)
+        if (v[i])
+	{
+	  elt_t e = v[i];
+	  for (unsigned int j = 0; j < ELT_BITS; j++)
+	    if (e & (elt_t (1) << j))
+	      return i * ELT_BITS + j;
+	}
+      return INVALID;
+    }
+    inline hb_codepoint_t get_max (void) const
+    {
+      for (int i = len () - 1; i >= 0; i--)
+        if (v[i])
+	{
+	  elt_t e = v[i];
+	  for (int j = ELT_BITS - 1; j >= 0; j--)
+	    if (e & (elt_t (1) << j))
+	      return i * ELT_BITS + j;
+	}
+      return 0;
+    }
 
+    static const unsigned int PAGE_BITS = 8192; /* Use to tune. */
+    static_assert ((PAGE_BITS & ((PAGE_BITS) - 1)) == 0, "");
 
+    typedef uint64_t elt_t;
 
-/*
- * hb_set_t
- */
+#if 0 && HAVE_VECTOR_SIZE
+    /* The vectorized version does not work with clang as non-const
+     * elt() errs "non-const reference cannot bind to vector element". */
+    typedef elt_t vector_t __attribute__((vector_size (PAGE_BITS / 8)));
+#else
+    typedef hb_vector_size_t<elt_t, PAGE_BITS / 8> vector_t;
+#endif
 
+    vector_t v;
 
-/* TODO Make this faster and memmory efficient. */
+    static const unsigned int ELT_BITS = sizeof (elt_t) * 8;
+    static const unsigned int ELT_MASK = ELT_BITS - 1;
+    static const unsigned int BITS = sizeof (vector_t) * 8;
+    static const unsigned int MASK = BITS - 1;
+    static_assert (PAGE_BITS == BITS, "");
 
-struct hb_set_t
-{
-  friend struct hb_frozen_set_t;
+    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); }
+  };
+  static_assert (page_t::PAGE_BITS == sizeof (page_t) * 8, "");
 
   hb_object_header_t header;
   ASSERT_POD ();
   bool in_error;
+  hb_prealloced_array_t<page_map_t, 8> page_map;
+  hb_prealloced_array_t<page_t, 1> pages;
 
-  inline void init (void) {
-    hb_object_init (this);
-    clear ();
+  inline void init (void)
+  {
+    page_map.init ();
+    pages.init ();
   }
-  inline void fini (void) {
+  inline void finish (void)
+  {
+    page_map.finish ();
+    pages.finish ();
+  }
+
+  inline bool resize (unsigned int count)
+  {
+    if (unlikely (in_error)) return false;
+    if (!pages.resize (count) || !page_map.resize (count))
+    {
+      pages.resize (page_map.len);
+      in_error = true;
+      return false;
+    }
+    return true;
   }
+
   inline void clear (void) {
     if (unlikely (hb_object_is_inert (this)))
       return;
     in_error = false;
-    memset (elts, 0, sizeof elts);
+    page_map.resize (0);
+    pages.resize (0);
   }
   inline bool is_empty (void) const {
-    for (unsigned int i = 0; i < ARRAY_LENGTH (elts); i++)
-      if (elts[i])
+    unsigned int count = pages.len;
+    for (unsigned int i = 0; i < count; i++)
+      if (!pages[i].is_empty ())
         return false;
     return true;
   }
+
   inline void add (hb_codepoint_t g)
   {
     if (unlikely (in_error)) return;
     if (unlikely (g == INVALID)) return;
-    if (unlikely (g > MAX_G)) return;
-    elt (g) |= mask (g);
+    page_t *page = page_for_insert (g); if (unlikely (!page)) return;
+    page->add (g);
   }
-  inline void add_range (hb_codepoint_t a, hb_codepoint_t b)
+  inline bool add_range (hb_codepoint_t a, hb_codepoint_t b)
+  {
+    if (unlikely (in_error)) return true; /* https://github.com/harfbuzz/harfbuzz/issues/657 */
+    if (unlikely (a > b || a == INVALID || b == INVALID)) return false;
+    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 (in_error)) return;
-    /* TODO Speedup */
-    for (unsigned int i = a; i < b + 1; i++)
-      add (i);
+    if (!count) return;
+    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++;
+	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 (in_error)) return true; /* https://github.com/harfbuzz/harfbuzz/issues/657 */
+    if (!count) return true;
+    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++;
+	count--;
+      }
+      while (count && (g = *array, g < end));
+    }
+    return true;
   }
+
   inline void del (hb_codepoint_t g)
   {
     if (unlikely (in_error)) return;
-    if (unlikely (g > MAX_G)) return;
-    elt (g) &= ~mask (g);
+    page_t *p = page_for (g);
+    if (!p)
+      return;
+    p->del (g);
   }
   inline void del_range (hb_codepoint_t a, hb_codepoint_t b)
   {
+    /* TODO Optimize, like add_range(). */
     if (unlikely (in_error)) return;
-    /* TODO Speedup */
     for (unsigned int i = a; i < b + 1; i++)
       del (i);
   }
   inline bool has (hb_codepoint_t g) const
   {
-    if (unlikely (g > MAX_G)) return false;
-    return !!(elt (g) & mask (g));
+    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
   {
-    if (unlikely (first > MAX_G)) return false;
-    if (unlikely (last  > MAX_G)) last = MAX_G;
-    unsigned int end = last + 1;
-    for (hb_codepoint_t i = first; i < end; i++)
-      if (has (i))
-        return true;
-    return false;
+    hb_codepoint_t c = first - 1;
+    return next (&c) && c <= last;
+  }
+  inline void set (const hb_set_t *other)
+  {
+    if (unlikely (in_error)) return;
+    unsigned int count = other->pages.len;
+    if (!resize (count))
+      return;
+
+    memcpy (pages.array, other->pages.array, count * sizeof (pages.array[0]));
+    memcpy (page_map.array, other->page_map.array, count * sizeof (page_map.array[0]));
   }
+
   inline bool is_equal (const hb_set_t *other) const
   {
-    for (unsigned int i = 0; i < ELTS; i++)
-      if (elts[i] != other->elts[i])
+    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 void set (const hb_set_t *other)
+
+  template <class Op>
+  inline void process (const hb_set_t *other)
   {
     if (unlikely (in_error)) return;
-    for (unsigned int i = 0; i < ELTS; i++)
-      elts[i] = other->elts[i];
+
+    unsigned int na = pages.len;
+    unsigned int nb = other->pages.len;
+
+    unsigned int count = 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 (!resize (count))
+      return;
+
+    /* 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--;
+        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)
+	  page_at (--count).v = page_at (a).v;
+      }
+      else
+      {
+        b--;
+        if (Op::passthru_right)
+	  page_at (--count).v = other->page_at (b).v;
+      }
+    }
+    if (Op::passthru_left)
+      while (a)
+	page_at (--count).v = page_at (--a).v;
+    if (Op::passthru_right)
+      while (b)
+	page_at (--count).v = other->page_at (--b).v;
+    assert (!count);
   }
+
   inline void union_ (const hb_set_t *other)
   {
-    if (unlikely (in_error)) return;
-    for (unsigned int i = 0; i < ELTS; i++)
-      elts[i] |= other->elts[i];
+    process<HbOpOr> (other);
   }
   inline void intersect (const hb_set_t *other)
   {
-    if (unlikely (in_error)) return;
-    for (unsigned int i = 0; i < ELTS; i++)
-      elts[i] &= other->elts[i];
+    process<HbOpAnd> (other);
   }
   inline void subtract (const hb_set_t *other)
   {
-    if (unlikely (in_error)) return;
-    for (unsigned int i = 0; i < ELTS; i++)
-      elts[i] &= ~other->elts[i];
+    process<HbOpMinus> (other);
   }
   inline void symmetric_difference (const hb_set_t *other)
   {
-    if (unlikely (in_error)) return;
-    for (unsigned int i = 0; i < ELTS; i++)
-      elts[i] ^= other->elts[i];
-  }
-  inline void invert (void)
-  {
-    if (unlikely (in_error)) return;
-    for (unsigned int i = 0; i < ELTS; i++)
-      elts[i] = ~elts[i];
+    process<HbOpXor> (other);
   }
   inline bool next (hb_codepoint_t *codepoint) const
   {
     if (unlikely (*codepoint == INVALID)) {
-      hb_codepoint_t i = get_min ();
-      if (i != INVALID) {
-        *codepoint = i;
-	return true;
-      } else {
-	*codepoint = INVALID;
-        return false;
+      *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)
+    {
+      if (pages[page_map[i].index].next (codepoint))
+      {
+	*codepoint += page_map[i].major * page_t::PAGE_BITS;
+        return true;
       }
+      i++;
     }
-    for (hb_codepoint_t i = *codepoint + 1; i < MAX_G + 1; i++)
-      if (has (i)) {
-        *codepoint = 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;
   }
@@ -303,99 +511,66 @@ struct hb_set_t
 
   inline unsigned int get_population (void) const
   {
-    unsigned int count = 0;
-    for (unsigned int i = 0; i < ELTS; i++)
-      count += _hb_popcount32 (elts[i]);
-    return count;
+    unsigned int pop = 0;
+    unsigned int count = pages.len;
+    for (unsigned int i = 0; i < count; i++)
+      pop += pages[i].get_population ();
+    return pop;
   }
   inline hb_codepoint_t get_min (void) const
   {
-    for (unsigned int i = 0; i < ELTS; i++)
-      if (elts[i])
-	for (unsigned int j = 0; j < BITS; j++)
-	  if (elts[i] & (1u << j))
-	    return i * BITS + j;
+    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
   {
-    for (unsigned int i = ELTS; i; i--)
-      if (elts[i - 1])
-	for (unsigned int j = BITS; j; j--)
-	  if (elts[i - 1] & (1u << (j - 1)))
-	    return (i - 1) * BITS + (j - 1);
+    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;
   }
 
-  typedef uint32_t elt_t;
-  static const unsigned int MAX_G = 65536 - 1; /* XXX Fix this... */
-  static const unsigned int SHIFT = 5;
-  static const unsigned int BITS = (1 << SHIFT);
-  static const unsigned int MASK = BITS - 1;
-  static const unsigned int ELTS = (MAX_G + 1 + (BITS - 1)) / BITS;
   static  const hb_codepoint_t INVALID = HB_SET_VALUE_INVALID;
 
-  elt_t &elt (hb_codepoint_t g) { return elts[g >> SHIFT]; }
-  elt_t const &elt (hb_codepoint_t g) const { return elts[g >> SHIFT]; }
-  elt_t mask (hb_codepoint_t g) const { return elt_t (1) << (g & MASK); }
-
-  elt_t elts[ELTS]; /* XXX 8kb */
-
-  ASSERT_STATIC (sizeof (elt_t) * 8 == BITS);
-  ASSERT_STATIC (sizeof (elt_t) * 8 * ELTS > MAX_G);
-};
-
-struct hb_frozen_set_t
-{
-  static const unsigned int SHIFT = hb_set_t::SHIFT;
-  static const unsigned int BITS = hb_set_t::BITS;
-  static const unsigned int MASK = hb_set_t::MASK;
-  typedef hb_set_t::elt_t elt_t;
-
-  inline void init (const hb_set_t &set)
+  inline page_t *page_for_insert (hb_codepoint_t g)
   {
-    start = count = 0;
-    elts = NULL;
-
-    unsigned int max = set.get_max ();
-    if (max == set.INVALID)
-      return;
-    unsigned int min = set.get_min ();
-    const elt_t &min_elt = set.elt (min);
-
-    start = min & ~MASK;
-    count = max - start + 1;
-    unsigned int num_elts = (count + BITS - 1) / BITS;
-    unsigned int elts_size = num_elts * sizeof (elt_t);
-    elts = (elt_t *) malloc (elts_size);
-    if (unlikely (!elts))
+    page_map_t map = {get_major (g), pages.len};
+    unsigned int i;
+    if (!page_map.bfind (&map, &i))
     {
-      start = count = 0;
-      return;
+      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;
     }
-    memcpy (elts, &min_elt, elts_size);
+    return &pages[page_map[i].index];
   }
-
-  inline void fini (void)
+  inline page_t *page_for (hb_codepoint_t g)
   {
-    if (elts)
-      free (elts);
+    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 bool has (hb_codepoint_t g) const
+  inline const page_t *page_for (hb_codepoint_t g) const
   {
-    /* hb_codepoint_t is unsigned. */
-    g -= start;
-    if (unlikely (g > count)) return false;
-    return !!(elt (g) & mask (g));
-  }
-
-  elt_t const &elt (hb_codepoint_t g) const { return elts[g >> SHIFT]; }
-  elt_t mask (hb_codepoint_t g) const { return elt_t (1) << (g & MASK); }
-
-  private:
-  hb_codepoint_t start, count;
-  elt_t *elts;
+    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; }
 };