Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 964 insertions, 0 deletions

diff --git a/gfx/harfbuzz/src/hb-bit-set.hh b/gfx/harfbuzz/src/hb-bit-set.hh
new file mode 100644
index 0000000000..8de6e037fb
--- /dev/null
+++ b/gfx/harfbuzz/src/hb-bit-set.hh
@@ -0,0 +1,964 @@
+/*
+ * Copyright © 2012,2017  Google, Inc.
+ * Copyright © 2021 Behdad Esfahbod
+ *
+ *  This is part of HarfBuzz, a text shaping library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Google Author(s): Behdad Esfahbod
+ */
+
+#ifndef HB_BIT_SET_HH
+#define HB_BIT_SET_HH
+
+#include "hb.hh"
+#include "hb-bit-page.hh"
+#include "hb-machinery.hh"
+
+
+struct hb_bit_set_t
+{
+  hb_bit_set_t () = default;
+  ~hb_bit_set_t () = default;
+
+  hb_bit_set_t (const hb_bit_set_t& other) : hb_bit_set_t () { set (other); }
+  hb_bit_set_t ( hb_bit_set_t&& other) : hb_bit_set_t () { hb_swap (*this, other); }
+  hb_bit_set_t& operator= (const hb_bit_set_t& other) { set (other); return *this; }
+  hb_bit_set_t& operator= (hb_bit_set_t&& other) { hb_swap (*this, other); return *this; }
+  friend void swap (hb_bit_set_t &a, hb_bit_set_t &b)
+  {
+    if (likely (!a.successful || !b.successful))
+      return;
+    hb_swap (a.population, b.population);
+    hb_swap (a.last_page_lookup, b.last_page_lookup);
+    hb_swap (a.page_map, b.page_map);
+    hb_swap (a.pages, b.pages);
+  }
+
+  void init ()
+  {
+    successful = true;
+    population = 0;
+    last_page_lookup = 0;
+    page_map.init ();
+    pages.init ();
+  }
+  void fini ()
+  {
+    page_map.fini ();
+    pages.fini ();
+  }
+
+  using page_t = hb_bit_page_t;
+  struct page_map_t
+  {
+    int cmp (const page_map_t &o) const { return cmp (o.major); }
+    int cmp (uint32_t o_major) const { return (int) o_major - (int) major; }
+
+    uint32_t major;
+    uint32_t index;
+  };
+
+  bool successful = true; /* Allocations successful */
+  mutable unsigned int population = 0;
+  mutable hb_atomic_int_t last_page_lookup = 0;
+  hb_sorted_vector_t<page_map_t> page_map;
+  hb_vector_t<page_t> pages;
+
+  void err () { if (successful) successful = false; } /* TODO Remove */
+  bool in_error () const { return !successful; }
+
+  bool resize (unsigned int count, bool clear = true)
+  {
+    if (unlikely (!successful)) return false;
+    if (unlikely (!pages.resize (count, clear) || !page_map.resize (count, clear)))
+    {
+      pages.resize (page_map.length);
+      successful = false;
+      return false;
+    }
+    return true;
+  }
+
+  void alloc (unsigned sz)
+  {
+    sz >>= (page_t::PAGE_BITS_LOG_2 - 1);
+    pages.alloc (sz);
+    page_map.alloc (sz);
+  }
+
+  void reset ()
+  {
+    successful = true;
+    clear ();
+  }
+
+  void clear ()
+  {
+    resize (0);
+    if (likely (successful))
+      population = 0;
+  }
+  bool is_empty () const
+  {
+    unsigned int count = pages.length;
+    for (unsigned int i = 0; i < count; i++)
+      if (!pages[i].is_empty ())
+	return false;
+    return true;
+  }
+  explicit operator bool () const { return !is_empty (); }
+
+  uint32_t hash () const
+  {
+    uint32_t h = 0;
+    for (auto &map : page_map)
+      h = h * 31 + hb_hash (map.major) + hb_hash (pages[map.index]);
+    return h;
+  }
+
+  private:
+  void dirty () { population = UINT_MAX; }
+  public:
+
+  void add (hb_codepoint_t g)
+  {
+    if (unlikely (!successful)) return;
+    if (unlikely (g == INVALID)) return;
+    dirty ();
+    page_t *page = page_for (g, true); if (unlikely (!page)) return;
+    page->add (g);
+  }
+  bool add_range (hb_codepoint_t a, hb_codepoint_t b)
+  {
+    if (unlikely (!successful)) return true; /* https://github.com/harfbuzz/harfbuzz/issues/657 */
+    if (unlikely (a > b || a == INVALID || b == INVALID)) return false;
+    dirty ();
+    unsigned int ma = get_major (a);
+    unsigned int mb = get_major (b);
+    if (ma == mb)
+    {
+      page_t *page = page_for (a, true); if (unlikely (!page)) return false;
+      page->add_range (a, b);
+    }
+    else
+    {
+      page_t *page = page_for (a, true); if (unlikely (!page)) return false;
+      page->add_range (a, major_start (ma + 1) - 1);
+
+      for (unsigned int m = ma + 1; m < mb; m++)
+      {
+	page = page_for (major_start (m), true); if (unlikely (!page)) return false;
+	page->init1 ();
+      }
+
+      page = page_for (b, true); if (unlikely (!page)) return false;
+      page->add_range (major_start (mb), b);
+    }
+    return true;
+  }
+
+  template <typename T>
+  void set_array (bool v, const T *array, unsigned int count, unsigned int stride=sizeof(T))
+  {
+    if (unlikely (!successful)) return;
+    if (!count) return;
+    dirty ();
+    hb_codepoint_t g = *array;
+    while (count)
+    {
+      unsigned int m = get_major (g);
+      page_t *page = page_for (g, v); if (unlikely (v && !page)) return;
+      unsigned int start = major_start (m);
+      unsigned int end = major_start (m + 1);
+      do
+      {
+        if (v || page) /* The v check is to optimize out the page check if v is true. */
+	  page->set (g, v);
+
+	array = &StructAtOffsetUnaligned<T> (array, stride);
+	count--;
+      }
+      while (count && (g = *array, start <= g && g < end));
+    }
+  }
+
+  template <typename T>
+  void add_array (const T *array, unsigned int count, unsigned int stride=sizeof(T))
+  { set_array (true, array, count, stride); }
+  template <typename T>
+  void add_array (const hb_array_t<const T>& arr) { add_array (&arr, arr.len ()); }
+
+  template <typename T>
+  void del_array (const T *array, unsigned int count, unsigned int stride=sizeof(T))
+  { set_array (false, array, count, stride); }
+  template <typename T>
+  void del_array (const hb_array_t<const T>& arr) { del_array (&arr, arr.len ()); }
+
+  /* Might return false if array looks unsorted.
+   * Used for faster rejection of corrupt data. */
+  template <typename T>
+  bool set_sorted_array (bool v, const T *array, unsigned int count, unsigned int stride=sizeof(T))
+  {
+    if (unlikely (!successful)) return true; /* https://github.com/harfbuzz/harfbuzz/issues/657 */
+    if (unlikely (!count)) return true;
+    dirty ();
+    hb_codepoint_t g = *array;
+    hb_codepoint_t last_g = g;
+    while (count)
+    {
+      unsigned int m = get_major (g);
+      page_t *page = page_for (g, v); if (unlikely (v && !page)) return false;
+      unsigned int end = major_start (m + 1);
+      do
+      {
+	/* If we try harder we can change the following comparison to <=;
+	 * Not sure if it's worth it. */
+	if (g < last_g) return false;
+	last_g = g;
+
+        if (v || page) /* The v check is to optimize out the page check if v is true. */
+	  page->add (g);
+
+	array = &StructAtOffsetUnaligned<T> (array, stride);
+	count--;
+      }
+      while (count && (g = *array, g < end));
+    }
+    return true;
+  }
+
+  template <typename T>
+  bool add_sorted_array (const T *array, unsigned int count, unsigned int stride=sizeof(T))
+  { return set_sorted_array (true, array, count, stride); }
+  template <typename T>
+  bool add_sorted_array (const hb_sorted_array_t<const T>& arr) { return add_sorted_array (&arr, arr.len ()); }
+
+  template <typename T>
+  bool del_sorted_array (const T *array, unsigned int count, unsigned int stride=sizeof(T))
+  { return set_sorted_array (false, array, count, stride); }
+  template <typename T>
+  bool del_sorted_array (const hb_sorted_array_t<const T>& arr) { return del_sorted_array (&arr, arr.len ()); }
+
+  void del (hb_codepoint_t g)
+  {
+    if (unlikely (!successful)) return;
+    page_t *page = page_for (g);
+    if (!page)
+      return;
+    dirty ();
+    page->del (g);
+  }
+
+  private:
+  void del_pages (int ds, int de)
+  {
+    if (ds <= de)
+    {
+      // Pre-allocate the workspace that compact() will need so we can bail on allocation failure
+      // before attempting to rewrite the page map.
+      hb_vector_t<unsigned> compact_workspace;
+      if (unlikely (!allocate_compact_workspace (compact_workspace))) return;
+
+      unsigned int write_index = 0;
+      for (unsigned int i = 0; i < page_map.length; i++)
+      {
+	int m = (int) page_map[i].major;
+	if (m < ds || de < m)
+	  page_map[write_index++] = page_map[i];
+      }
+      compact (compact_workspace, write_index);
+      resize (write_index);
+    }
+  }
+
+
+  public:
+  void del_range (hb_codepoint_t a, hb_codepoint_t b)
+  {
+    if (unlikely (!successful)) return;
+    if (unlikely (a > b || a == INVALID)) return;
+    dirty ();
+    unsigned int ma = get_major (a);
+    unsigned int mb = get_major (b);
+    /* Delete pages from ds through de if ds <= de. */
+    int ds = (a == major_start (ma))? (int) ma: (int) (ma + 1);
+    int de = (b + 1 == major_start (mb + 1))? (int) mb: ((int) mb - 1);
+    if (ds > de || (int) ma < ds)
+    {
+      page_t *page = page_for (a);
+      if (page)
+      {
+	if (ma == mb)
+	  page->del_range (a, b);
+	else
+	  page->del_range (a, major_start (ma + 1) - 1);
+      }
+    }
+    if (de < (int) mb && ma != mb)
+    {
+      page_t *page = page_for (b);
+      if (page)
+	page->del_range (major_start (mb), b);
+    }
+    del_pages (ds, de);
+  }
+
+  bool get (hb_codepoint_t g) const
+  {
+    const page_t *page = page_for (g);
+    if (!page)
+      return false;
+    return page->get (g);
+  }
+
+  /* Has interface. */
+  bool operator [] (hb_codepoint_t k) const { return get (k); }
+  bool has (hb_codepoint_t k) const { return (*this)[k]; }
+  /* 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, false)))
+      return;
+    population = other.population;
+
+    page_map = other.page_map;
+    pages = other.pages;
+  }
+
+  bool is_equal (const hb_bit_set_t &other) const
+  {
+    if (has_population () && other.has_population () &&
+	population != other.population)
+      return false;
+
+    unsigned int na = pages.length;
+    unsigned int nb = other.pages.length;
+
+    unsigned int a = 0, b = 0;
+    for (; a < na && b < nb; )
+    {
+      if (page_at (a).is_empty ()) { a++; continue; }
+      if (other.page_at (b).is_empty ()) { b++; continue; }
+      if (page_map[a].major != other.page_map[b].major ||
+	  !page_at (a).is_equal (other.page_at (b)))
+	return false;
+      a++;
+      b++;
+    }
+    for (; a < na; a++)
+      if (!page_at (a).is_empty ()) { return false; }
+    for (; b < nb; b++)
+      if (!other.page_at (b).is_empty ()) { return false; }
+
+    return true;
+  }
+
+  bool is_subset (const hb_bit_set_t &larger_set) const
+  {
+    if (has_population () && larger_set.has_population () &&
+	population > larger_set.population)
+      return false;
+
+    uint32_t spi = 0;
+    for (uint32_t lpi = 0; spi < page_map.length && lpi < larger_set.page_map.length; lpi++)
+    {
+      uint32_t spm = page_map[spi].major;
+      uint32_t lpm = larger_set.page_map[lpi].major;
+      auto sp = page_at (spi);
+      auto lp = larger_set.page_at (lpi);
+
+      if (spm < lpm && !sp.is_empty ())
+        return false;
+
+      if (lpm < spm)
+        continue;
+
+      if (!sp.is_subset (lp))
+        return false;
+
+      spi++;
+    }
+
+    while (spi < page_map.length)
+      if (!page_at (spi++).is_empty ())
+        return false;
+
+    return true;
+  }
+
+  private:
+  bool allocate_compact_workspace (hb_vector_t<unsigned>& workspace)
+  {
+    if (unlikely (!workspace.resize (pages.length)))
+    {
+      successful = false;
+      return false;
+    }
+
+    return true;
+  }
+
+  /*
+   * workspace should be a pre-sized vector allocated to hold at exactly pages.length
+   * elements.
+   */
+  void compact (hb_vector_t<unsigned>& workspace,
+                unsigned int length)
+  {
+    assert(workspace.length == pages.length);
+    hb_vector_t<unsigned>& old_index_to_page_map_index = workspace;
+
+    hb_fill (old_index_to_page_map_index.writer(), 0xFFFFFFFF);
+    for (unsigned i = 0; i < length; i++)
+      old_index_to_page_map_index[page_map[i].index] =  i;
+
+    compact_pages (old_index_to_page_map_index);
+  }
+  void compact_pages (const hb_vector_t<unsigned>& old_index_to_page_map_index)
+  {
+    unsigned int write_index = 0;
+    for (unsigned int i = 0; i < pages.length; i++)
+    {
+      if (old_index_to_page_map_index[i] == 0xFFFFFFFF) continue;
+
+      if (write_index < i)
+	pages[write_index] = pages[i];
+
+      page_map[old_index_to_page_map_index[i]].index = write_index;
+      write_index++;
+    }
+  }
+  public:
+
+  void process_ (hb_bit_page_t::vector_t (*op) (const hb_bit_page_t::vector_t &, const hb_bit_page_t::vector_t &),
+		 bool passthru_left, bool passthru_right,
+		 const hb_bit_set_t &other)
+  {
+    if (unlikely (!successful)) return;
+
+    dirty ();
+
+    unsigned int na = pages.length;
+    unsigned int nb = other.pages.length;
+    unsigned int next_page = na;
+
+    unsigned int count = 0, newCount = 0;
+    unsigned int a = 0, b = 0;
+    unsigned int write_index = 0;
+
+    // Pre-allocate the workspace that compact() will need so we can bail on allocation failure
+    // before attempting to rewrite the page map.
+    hb_vector_t<unsigned> compact_workspace;
+    if (!passthru_left && unlikely (!allocate_compact_workspace (compact_workspace))) return;
+
+    for (; a < na && b < nb; )
+    {
+      if (page_map[a].major == other.page_map[b].major)
+      {
+	if (!passthru_left)
+	{
+	  // Move page_map entries that we're keeping from the left side set
+	  // to the front of the page_map vector. This isn't necessary if
+	  // passthru_left is set since no left side pages will be removed
+	  // in that case.
+	  if (write_index < a)
+	    page_map[write_index] = page_map[a];
+	  write_index++;
+	}
+
+	count++;
+	a++;
+	b++;
+      }
+      else if (page_map[a].major < other.page_map[b].major)
+      {
+	if (passthru_left)
+	  count++;
+	a++;
+      }
+      else
+      {
+	if (passthru_right)
+	  count++;
+	b++;
+      }
+    }
+    if (passthru_left)
+      count += na - a;
+    if (passthru_right)
+      count += nb - b;
+
+    if (!passthru_left)
+    {
+      na  = write_index;
+      next_page = write_index;
+      compact (compact_workspace, write_index);
+    }
+
+    if (unlikely (!resize (count)))
+      return;
+
+    newCount = count;
+
+    /* Process in-place backward. */
+    a = na;
+    b = nb;
+    for (; a && b; )
+    {
+      if (page_map.arrayZ[a - 1].major == other.page_map.arrayZ[b - 1].major)
+      {
+	a--;
+	b--;
+	count--;
+	page_map.arrayZ[count] = page_map.arrayZ[a];
+	page_at (count).v = op (page_at (a).v, other.page_at (b).v);
+      }
+      else if (page_map.arrayZ[a - 1].major > other.page_map.arrayZ[b - 1].major)
+      {
+	a--;
+	if (passthru_left)
+	{
+	  count--;
+	  page_map.arrayZ[count] = page_map.arrayZ[a];
+	}
+      }
+      else
+      {
+	b--;
+	if (passthru_right)
+	{
+	  count--;
+	  page_map.arrayZ[count].major = other.page_map.arrayZ[b].major;
+	  page_map.arrayZ[count].index = next_page++;
+	  page_at (count).v = other.page_at (b).v;
+	}
+      }
+    }
+    if (passthru_left)
+      while (a)
+      {
+	a--;
+	count--;
+	page_map.arrayZ[count] = page_map.arrayZ[a];
+      }
+    if (passthru_right)
+      while (b)
+      {
+	b--;
+	count--;
+	page_map.arrayZ[count].major = other.page_map.arrayZ[b].major;
+	page_map.arrayZ[count].index = next_page++;
+	page_at (count).v = other.page_at (b).v;
+      }
+    assert (!count);
+    resize (newCount);
+  }
+  template <typename Op>
+  static hb_bit_page_t::vector_t
+  op_ (const hb_bit_page_t::vector_t &a, const hb_bit_page_t::vector_t &b)
+  { return Op{} (a, b); }
+  template <typename Op>
+  void process (const Op& op, const hb_bit_set_t &other)
+  {
+    process_ (op_<Op>, op (1, 0), op (0, 1), other);
+  }
+
+  void union_ (const hb_bit_set_t &other) { process (hb_bitwise_or, other); }
+  void intersect (const hb_bit_set_t &other) { process (hb_bitwise_and, other); }
+  void subtract (const hb_bit_set_t &other) { process (hb_bitwise_gt, other); }
+  void symmetric_difference (const hb_bit_set_t &other) { process (hb_bitwise_xor, other); }
+
+  bool next (hb_codepoint_t *codepoint) const
+  {
+    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_array[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.arrayZ[i].major == map.major)
+    {
+      if (pages[page_map.arrayZ[i].index].previous (codepoint))
+      {
+	*codepoint += page_map.arrayZ[i].major * page_t::PAGE_BITS;
+	return true;
+      }
+    }
+    i--;
+    for (; (int) i >= 0; i--)
+    {
+      hb_codepoint_t m = pages.arrayZ[page_map.arrayZ[i].index].get_max ();
+      if (m != INVALID)
+      {
+	*codepoint = page_map.arrayZ[i].major * page_t::PAGE_BITS + m;
+	return true;
+      }
+    }
+    *codepoint = INVALID;
+    return false;
+  }
+  bool next_range (hb_codepoint_t *first, hb_codepoint_t *last) const
+  {
+    hb_codepoint_t i;
+
+    i = *last;
+    if (!next (&i))
+    {
+      *last = *first = INVALID;
+      return false;
+    }
+
+    /* TODO Speed up. */
+    *last = *first = i;
+    while (next (&i) && i == *last + 1)
+      (*last)++;
+
+    return true;
+  }
+  bool previous_range (hb_codepoint_t *first, hb_codepoint_t *last) const
+  {
+    hb_codepoint_t i;
+
+    i = *first;
+    if (!previous (&i))
+    {
+      *last = *first = INVALID;
+      return false;
+    }
+
+    /* TODO Speed up. */
+    *last = *first = i;
+    while (previous (&i) && i == *first - 1)
+      (*first)--;
+
+    return true;
+  }
+
+  unsigned int next_many (hb_codepoint_t  codepoint,
+			  hb_codepoint_t *out,
+			  unsigned int    size) const
+  {
+    // By default, start at the first bit of the first page of values.
+    unsigned int start_page = 0;
+    unsigned int start_page_value = 0;
+    if (unlikely (codepoint != INVALID))
+    {
+      const auto* page_map_array = page_map.arrayZ;
+      unsigned int major = get_major (codepoint);
+      unsigned int i = last_page_lookup;
+      if (unlikely (i >= page_map.length || page_map_array[i].major != major))
+      {
+	page_map.bfind (major, &i, HB_NOT_FOUND_STORE_CLOSEST);
+	if (i >= page_map.length)
+	  return 0;  // codepoint is greater than our max element.
+      }
+      start_page = i;
+      start_page_value = page_remainder (codepoint + 1);
+      if (unlikely (start_page_value == 0))
+      {
+        // The export-after value was last in the page. Start on next page.
+        start_page++;
+        start_page_value = 0;
+      }
+    }
+
+    unsigned int initial_size = size;
+    for (unsigned int i = start_page; i < page_map.length && size; i++)
+    {
+      uint32_t base = major_start (page_map[i].major);
+      unsigned int n = pages[page_map[i].index].write (base, start_page_value, out, size);
+      out += n;
+      size -= n;
+      start_page_value = 0;
+    }
+    return initial_size - size;
+  }
+
+  unsigned int next_many_inverted (hb_codepoint_t  codepoint,
+				   hb_codepoint_t *out,
+				   unsigned int    size) const
+  {
+    unsigned int initial_size = size;
+    // By default, start at the first bit of the first page of values.
+    unsigned int start_page = 0;
+    unsigned int start_page_value = 0;
+    if (unlikely (codepoint != INVALID))
+    {
+      const auto* page_map_array = page_map.arrayZ;
+      unsigned int major = get_major (codepoint);
+      unsigned int i = last_page_lookup;
+      if (unlikely (i >= page_map.length || page_map_array[i].major != major))
+      {
+        page_map.bfind(major, &i, HB_NOT_FOUND_STORE_CLOSEST);
+        if (unlikely (i >= page_map.length))
+        {
+          // codepoint is greater than our max element.
+          while (++codepoint != INVALID && size)
+          {
+            *out++ = codepoint;
+            size--;
+          }
+          return initial_size - size;
+        }
+      }
+      start_page = i;
+      start_page_value = page_remainder (codepoint + 1);
+      if (unlikely (start_page_value == 0))
+      {
+        // The export-after value was last in the page. Start on next page.
+        start_page++;
+        start_page_value = 0;
+      }
+    }
+
+    hb_codepoint_t next_value = codepoint + 1;
+    for (unsigned int i=start_page; i<page_map.length && size; i++)
+    {
+      uint32_t base = major_start (page_map[i].major);
+      unsigned int n = pages[page_map[i].index].write_inverted (base, start_page_value, out, size, &next_value);
+      out += n;
+      size -= n;
+      start_page_value = 0;
+    }
+    while (next_value < HB_SET_VALUE_INVALID && size) {
+      *out++ = next_value++;
+      size--;
+    }
+    return initial_size - size;
+  }
+
+  bool has_population () const { return population != UINT_MAX; }
+  unsigned int get_population () const
+  {
+    if (has_population ())
+      return population;
+
+    unsigned int pop = 0;
+    unsigned int count = pages.length;
+    for (unsigned int i = 0; i < count; i++)
+      pop += pages[i].get_population ();
+
+    population = pop;
+    return pop;
+  }
+  hb_codepoint_t get_min () const
+  {
+    unsigned count = pages.length;
+    for (unsigned i = 0; i < count; i++)
+    {
+      const auto& map = page_map[i];
+      const auto& page = pages[map.index];
+
+      if (!page.is_empty ())
+	return map.major * page_t::PAGE_BITS + page.get_min ();
+    }
+    return INVALID;
+  }
+  hb_codepoint_t get_max () const
+  {
+    unsigned count = pages.length;
+    for (signed i = count - 1; i >= 0; i--)
+    {
+      const auto& map = page_map[(unsigned) i];
+      const auto& page = pages[map.index];
+
+      if (!page.is_empty ())
+	return map.major * page_t::PAGE_BITS + page.get_max ();
+    }
+    return INVALID;
+  }
+
+  static constexpr hb_codepoint_t INVALID = page_t::INVALID;
+
+  /*
+   * Iterator implementation.
+   */
+  struct iter_t : hb_iter_with_fallback_t<iter_t, hb_codepoint_t>
+  {
+    static constexpr bool is_sorted_iterator = true;
+    iter_t (const hb_bit_set_t &s_ = Null (hb_bit_set_t),
+	    bool init = true) : s (&s_), v (INVALID), l(0)
+    {
+      if (init)
+      {
+	l = s->get_population () + 1;
+	__next__ ();
+      }
+    }
+
+    typedef hb_codepoint_t __item_t__;
+    hb_codepoint_t __item__ () const { return v; }
+    bool __more__ () const { return v != INVALID; }
+    void __next__ () { s->next (&v); if (l) l--; }
+    void __prev__ () { s->previous (&v); }
+    unsigned __len__ () const { return l; }
+    iter_t end () const { return iter_t (*s, false); }
+    bool operator != (const iter_t& o) const
+    { return s != o.s || v != o.v; }
+
+    protected:
+    const hb_bit_set_t *s;
+    hb_codepoint_t v;
+    unsigned l;
+  };
+  iter_t iter () const { return iter_t (*this); }
+  operator iter_t () const { return iter (); }
+
+  protected:
+
+  page_t *page_for (hb_codepoint_t g, bool insert = false)
+  {
+    unsigned major = get_major (g);
+
+    /* The extra page_map length is necessary; can't just rely on vector here,
+     * since the next check would be tricked because a null page also has
+     * major==0, which we can't distinguish from an actualy major==0 page... */
+    unsigned i = last_page_lookup;
+    if (likely (i < page_map.length))
+    {
+      auto &cached_page = page_map.arrayZ[i];
+      if (cached_page.major == major)
+	return &pages.arrayZ[cached_page.index];
+    }
+
+    page_map_t map = {major, pages.length};
+    if (!page_map.bfind (map, &i, HB_NOT_FOUND_STORE_CLOSEST))
+    {
+      if (!insert)
+        return nullptr;
+
+      if (unlikely (!resize (pages.length + 1)))
+	return nullptr;
+
+      pages.arrayZ[map.index].init0 ();
+      memmove (page_map.arrayZ + i + 1,
+	       page_map.arrayZ + i,
+	       (page_map.length - 1 - i) * page_map.item_size);
+      page_map[i] = map;
+    }
+
+    last_page_lookup = i;
+    return &pages.arrayZ[page_map.arrayZ[i].index];
+  }
+  const page_t *page_for (hb_codepoint_t g) const
+  {
+    unsigned major = get_major (g);
+
+    /* The extra page_map length is necessary; can't just rely on vector here,
+     * since the next check would be tricked because a null page also has
+     * major==0, which we can't distinguish from an actualy major==0 page... */
+    unsigned i = last_page_lookup;
+    if (likely (i < page_map.length))
+    {
+      auto &cached_page = page_map.arrayZ[i];
+      if (cached_page.major == major)
+	return &pages.arrayZ[cached_page.index];
+    }
+
+    page_map_t key = {major};
+    if (!page_map.bfind (key, &i))
+      return nullptr;
+
+    last_page_lookup = i;
+    return &pages.arrayZ[page_map[i].index];
+  }
+  page_t &page_at (unsigned int i)
+  {
+    assert (i < page_map.length);
+    return pages.arrayZ[page_map.arrayZ[i].index];
+  }
+  const page_t &page_at (unsigned int i) const
+  {
+    assert (i < page_map.length);
+    return pages.arrayZ[page_map.arrayZ[i].index];
+  }
+  unsigned int get_major (hb_codepoint_t g) const { return g >> page_t::PAGE_BITS_LOG_2; }
+  unsigned int page_remainder (hb_codepoint_t g) const { return g & page_t::PAGE_BITMASK; }
+  hb_codepoint_t major_start (unsigned int major) const { return major << page_t::PAGE_BITS_LOG_2; }
+};
+
+
+#endif /* HB_BIT_SET_HH */