/*

 * Copyright © 1998-2004  David Turner and Werner Lemberg

 * Copyright © 2004,2007,2009,2010  Red Hat, Inc.

 * Copyright © 2011,2012  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.

 *

 * Red Hat Author(s): Owen Taylor, Behdad Esfahbod

 * Google Author(s): Behdad Esfahbod

 */

#ifndef HB_BUFFER_HH

#define HB_BUFFER_HH

#include "hb.hh"

#include "hb-unicode.hh"

#include "hb-set-digest.hh"

static_assert ((sizeof (hb_glyph_info_t) == 20), "");

static_assert ((sizeof (hb_glyph_info_t) == sizeof (hb_glyph_position_t)), "");

HB_MARK_AS_FLAG_T (hb_glyph_flags_t);

HB_MARK_AS_FLAG_T (hb_buffer_flags_t);

HB_MARK_AS_FLAG_T (hb_buffer_serialize_flags_t);

HB_MARK_AS_FLAG_T (hb_buffer_diff_flags_t);

enum hb_buffer_scratch_flags_t {

  HB_BUFFER_SCRATCH_FLAG_DEFAULT      = 0x00000000u,

  HB_BUFFER_SCRATCH_FLAG_HAS_FRACTION_SLASH   = 0x00000001u,

  HB_BUFFER_SCRATCH_FLAG_HAS_DEFAULT_IGNORABLES   = 0x00000002u,

  HB_BUFFER_SCRATCH_FLAG_HAS_SPACE_FALLBACK   = 0x00000004u,

  HB_BUFFER_SCRATCH_FLAG_HAS_GPOS_ATTACHMENT    = 0x00000008u,

  HB_BUFFER_SCRATCH_FLAG_HAS_CGJ      = 0x00000010u,

  HB_BUFFER_SCRATCH_FLAG_HAS_BROKEN_SYLLABLE    = 0x00000020u,

  HB_BUFFER_SCRATCH_FLAG_HAS_VARIATION_SELECTOR_FALLBACK= 0x00000040u,

  HB_BUFFER_SCRATCH_FLAG_HAS_CONTINUATIONS    = 0x00000080u,

  /* Reserved for shapers' internal use. */

  HB_BUFFER_SCRATCH_FLAG_SHAPER0      = 0x01000000u,

  HB_BUFFER_SCRATCH_FLAG_SHAPER1      = 0x02000000u,

  HB_BUFFER_SCRATCH_FLAG_SHAPER2      = 0x04000000u,

  HB_BUFFER_SCRATCH_FLAG_SHAPER3      = 0x08000000u,

};

HB_MARK_AS_FLAG_T (hb_buffer_scratch_flags_t);

/*

 * hb_buffer_t

 */

struct hb_buffer_t

{

  hb_object_header_t header;

  /*

   * Information about how the text in the buffer should be treated.

   */

  hb_unicode_funcs_t *unicode; /* Unicode functions */

  hb_buffer_flags_t flags; /* BOT / EOT / etc. */

  hb_buffer_cluster_level_t cluster_level;

  hb_codepoint_t replacement; /* U+FFFD or something else. */

  hb_codepoint_t invisible; /* 0 or something else. */

  hb_codepoint_t not_found; /* 0 or something else. */

  hb_codepoint_t not_found_variation_selector; /* HB_CODEPOINT_INVALID or something else. */

  /*

   * Buffer contents

   */

  hb_buffer_content_type_t content_type;

  hb_segment_properties_t props; /* Script, language, direction */

  bool successful; /* Allocations successful */

  bool have_output; /* Whether we have an output buffer going on */

  bool have_positions; /* Whether we have positions */

  unsigned int idx; /* Cursor into ->info and ->pos arrays */

  unsigned int len; /* Length of ->info and ->pos arrays */

  unsigned int out_len; /* Length of ->out_info array if have_output */

  unsigned int allocated; /* Length of allocated arrays */

  hb_glyph_info_t     *info;

  hb_glyph_info_t     *out_info;

  hb_glyph_position_t *pos;

  /* Text before / after the main buffer contents.

   * Always in Unicode, and ordered outward.

   * Index 0 is for "pre-context", 1 for "post-context". */

  static constexpr unsigned CONTEXT_LENGTH = 5u;

  hb_codepoint_t context[2][CONTEXT_LENGTH];

  unsigned int context_len[2];

  hb_set_digest_t digest; /* Manually updated sometimes */

  /*

   * Managed by enter / leave

   */

  uint8_t allocated_var_bits;

  uint8_t serial;

  uint32_t random_state;

  hb_buffer_scratch_flags_t scratch_flags; /* Have space-fallback, etc. */

  unsigned int max_len; /* Maximum allowed len. */

  int max_ops; /* Maximum allowed operations. */

  /* The bits here reflect current allocations of the bytes in glyph_info_t's var1 and var2. */

  /*

   * Messaging callback

   */

#ifndef HB_NO_BUFFER_MESSAGE

  typedef void (*changed_func_t) (hb_buffer_t *buffer, void *user_data);

  hb_buffer_message_func_t message_func;

  void *message_data;

  hb_destroy_func_t message_destroy;

  changed_func_t changed_func;

  void *changed_data;

  unsigned message_depth; /* How deeply are we inside a message callback? */

#else

  static constexpr unsigned message_depth = 0u;

#endif

  /* Methods */

  HB_NODISCARD bool in_error () const { return !successful; }

  void allocate_var (unsigned int start, unsigned int count)

  {

    unsigned int end = start + count;

    assert (end <= 8);

    unsigned int bits = (1u<<end) - (1u<<start);

    assert (0 == (allocated_var_bits & bits));

    allocated_var_bits |= bits;

  }

  bool try_allocate_var (unsigned int start, unsigned int count)

  {

    unsigned int end = start + count;

    assert (end <= 8);

    unsigned int bits = (1u<<end) - (1u<<start);

    if (allocated_var_bits & bits)

      return false;

    allocated_var_bits |= bits;

    return true;

  }

  void deallocate_var (unsigned int start, unsigned int count)

  {

    unsigned int end = start + count;

    assert (end <= 8);

    unsigned int bits = (1u<<end) - (1u<<start);

    assert (bits == (allocated_var_bits & bits));

    allocated_var_bits &= ~bits;

  }

  void assert_var (unsigned int start, unsigned int count)

  {

    unsigned int end = start + count;

    assert (end <= 8);

    HB_UNUSED unsigned int bits = (1u<<end) - (1u<<start);

    assert (bits == (allocated_var_bits & bits));

  }

  void deallocate_var_all ()

  {

    allocated_var_bits = 0;

  }

  HB_ALWAYS_INLINE

  hb_glyph_info_t &cur (unsigned int i = 0) { return info[idx + i]; }

  HB_ALWAYS_INLINE

  hb_glyph_info_t cur (unsigned int i = 0) const { return info[idx + i]; }

  HB_ALWAYS_INLINE

  hb_glyph_position_t &cur_pos (unsigned int i = 0) { return pos[idx + i]; }

  HB_ALWAYS_INLINE

  hb_glyph_position_t cur_pos (unsigned int i = 0) const { return pos[idx + i]; }

  HB_ALWAYS_INLINE

  hb_glyph_info_t &prev ()      { return out_info[out_len ? out_len - 1 : 0]; }

  HB_ALWAYS_INLINE

  hb_glyph_info_t prev () const { return out_info[out_len ? out_len - 1 : 0]; }

  template <typename set_t>

  void collect_codepoints (set_t &d) const

  { d.clear (); d.add_array (&info[0].codepoint, len, sizeof (info[0])); }

void hb_buffer_t::collect_codepoints<hb_bit_set_t>(hb_bit_set_t&) const

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  { d.clear (); d.add_array (&info[0].codepoint, len, sizeof (info[0])); }

void hb_buffer_t::collect_codepoints<hb_set_digest_t>(hb_set_digest_t&) const

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  { d.clear (); d.add_array (&info[0].codepoint, len, sizeof (info[0])); }

  void update_digest ()

  {

    digest = hb_set_digest_t ();

    collect_codepoints (digest);

  }

  HB_INTERNAL void similar (const hb_buffer_t &src);

  HB_INTERNAL void reset ();

  HB_INTERNAL void clear ();

  /* Called around shape() */

  HB_INTERNAL void enter ();

  HB_INTERNAL void leave ();

#ifndef HB_NO_BUFFER_VERIFY

  HB_INTERNAL

#endif

  bool verify (hb_buffer_t        *text_buffer,

         hb_font_t          *font,

         const hb_feature_t *features,

         unsigned int        num_features,

         const char * const *shapers)

#ifndef HB_NO_BUFFER_VERIFY

  ;

#else

  { return true; }

#endif

  unsigned int backtrack_len () const { return have_output ? out_len : idx; }

  unsigned int lookahead_len () const { return len - idx; }

  uint8_t next_serial () { return ++serial ? serial : ++serial; }

  HB_INTERNAL void add (hb_codepoint_t  codepoint,

      unsigned int    cluster);

  HB_INTERNAL void add_info (const hb_glyph_info_t &glyph_info);

  HB_INTERNAL void add_info_and_pos (const hb_glyph_info_t &glyph_info,

             const hb_glyph_position_t &glyph_pos);

  void reverse_range (unsigned start, unsigned end)

  {

    hb_array_t<hb_glyph_info_t> (info, len).reverse (start, end);

    if (have_positions)

      hb_array_t<hb_glyph_position_t> (pos, len).reverse (start, end);

  }

  void reverse () { reverse_range (0, len); }

  template <typename FuncType>

  void reverse_groups (const FuncType& group,

           bool merge_clusters = false)

  {

    if (unlikely (!len))

      return;

    unsigned start = 0;

    unsigned i;

    for (i = 1; i < len; i++)

    {

      if (!group (info[i - 1], info[i]))

      {

  if (merge_clusters)

    this->merge_clusters (start, i);

  reverse_range (start, i);

  start = i;

      }

    }

    if (merge_clusters)

      this->merge_clusters (start, i);

    reverse_range (start, i);

    reverse ();

  }

  template <typename FuncType>

  unsigned group_end (unsigned start, const FuncType& group) const

  {

    while (++start < len && group (info[start - 1], info[start]))

      ;

    return start;

  }

  static bool _cluster_group_func (const hb_glyph_info_t& a,

           const hb_glyph_info_t& b)

  { return a.cluster == b.cluster; }

  void reverse_clusters () { reverse_groups (_cluster_group_func); }

  HB_INTERNAL void guess_segment_properties ();

  HB_INTERNAL bool sync ();

  HB_INTERNAL int sync_so_far ();

  HB_INTERNAL void clear_output ();

  HB_INTERNAL void clear_positions ();

  template <typename T>

  HB_NODISCARD bool replace_glyphs (unsigned int num_in,

            unsigned int num_out,

            const T *glyph_data)

  {

    if (unlikely (!make_room_for (num_in, num_out))) return false;

    assert (idx + num_in <= len);

    merge_clusters (idx, idx + num_in);

    hb_glyph_info_t &orig_info = idx < len ? cur() : prev();

    hb_glyph_info_t *pinfo = &out_info[out_len];

    for (unsigned int i = 0; i < num_out; i++)

    {

      *pinfo = orig_info;

      pinfo->codepoint = glyph_data[i];

      pinfo++;

    }

    idx  += num_in;

    out_len += num_out;

    return true;

  }

  HB_NODISCARD bool replace_glyph (hb_codepoint_t glyph_index)

  { return replace_glyphs (1, 1, &glyph_index); }

  /* Makes a copy of the glyph at idx to output and replace glyph_index */

  HB_NODISCARD bool output_glyph (hb_codepoint_t glyph_index)

  { return replace_glyphs (0, 1, &glyph_index); }

  HB_NODISCARD bool output_info (const hb_glyph_info_t &glyph_info)

  {

    if (unlikely (!make_room_for (0, 1))) return false;

    out_info[out_len] = glyph_info;

    out_len++;

    return true;

  }

  /* Copies glyph at idx to output but doesn't advance idx */

  HB_NODISCARD bool copy_glyph ()

  {

    /* Extra copy because cur()'s return can be freed within

     * output_info() call if buffer reallocates. */

    return output_info (hb_glyph_info_t (cur()));

  }

  /* Copies glyph at idx to output and advance idx.

   * If there's no output, just advance idx. */

  HB_NODISCARD bool next_glyph ()

  {

    if (have_output)

    {

      if (out_info != info || out_len != idx)

      {

  if (unlikely (!ensure (out_len + 1))) return false;

  out_info[out_len] = info[idx];

      }

      out_len++;

    }

    idx++;

    return true;

  }

  /* Copies n glyphs at idx to output and advance idx.

   * If there's no output, just advance idx. */

  HB_NODISCARD bool next_glyphs (unsigned int n)

  {

    if (have_output)

    {

      if (out_info != info || out_len != idx)

      {

  if (unlikely (!ensure (out_len + n))) return false;

  memmove (out_info + out_len, info + idx, n * sizeof (out_info[0]));

      }

      out_len += n;

    }

    idx += n;

    return true;

  }

  /* Advance idx without copying to output. */

  void skip_glyph () { idx++; }

  void add_masks (hb_mask_t mask)

  {

    for (unsigned int j = 0; j < len; j++)

      info[j].mask |= mask;

  }

  HB_INTERNAL void set_masks (hb_mask_t value, hb_mask_t mask,

            unsigned int cluster_start, unsigned int cluster_end);

  void merge_clusters (unsigned int start, unsigned int end)

  {

    if (end - start < 2)

      return;

    if (!HB_BUFFER_CLUSTER_LEVEL_IS_MONOTONE (cluster_level))

    {

      unsafe_to_break (start, end);

      return;

    }

    merge_clusters_impl (start, end);

  }

  void merge_grapheme_clusters (unsigned int start, unsigned int end)

  {

    if (end - start < 2)

      return;

    if (!HB_BUFFER_CLUSTER_LEVEL_IS_GRAPHEMES (cluster_level))

    {

      unsafe_to_break (start, end);

      return;

    }

    merge_clusters_impl (start, end);

  }

  HB_INTERNAL void merge_clusters_impl (unsigned int start, unsigned int end);

  void merge_out_clusters (unsigned int start, unsigned int end)

  {

    if (end - start < 2)

      return;

    if (!HB_BUFFER_CLUSTER_LEVEL_IS_MONOTONE (cluster_level))

      return;

    merge_out_clusters_impl (start, end);

  }

  void merge_out_grapheme_clusters (unsigned int start, unsigned int end)

  {

    if (end - start < 2)

      return;

    if (!HB_BUFFER_CLUSTER_LEVEL_IS_GRAPHEMES (cluster_level))

      return;

    merge_out_clusters_impl (start, end);

  }

  HB_INTERNAL void merge_out_clusters_impl (unsigned int start, unsigned int end);

  /* Merge clusters for deleting current glyph, and skip it. */

  HB_INTERNAL void delete_glyph ();

  HB_INTERNAL void delete_glyphs_inplace (bool (*filter) (const hb_glyph_info_t *info));

  /* Adds glyph flags in mask to infos with clusters between start and end.

   * The start index will be from out-buffer if from_out_buffer is true.

   * If interior is true, then the cluster having the minimum value is skipped. */

  void _set_glyph_flags_impl (hb_mask_t mask,

            unsigned start,

            unsigned end,

            bool interior,

            bool from_out_buffer)

  {

    if (!from_out_buffer || !have_output)

    {

      if (!interior)

      {

  for (unsigned i = start; i < end; i++)

    info[i].mask |= mask;

      }

      else

      {

  unsigned cluster = _infos_find_min_cluster (info, start, end);

  _infos_set_glyph_flags (info, start, end, cluster, mask);

      }

    }

    else

    {

      assert (start <= out_len);

      assert (idx <= end);

      if (!interior)

      {

  for (unsigned i = start; i < out_len; i++)

    out_info[i].mask |= mask;

  for (unsigned i = idx; i < end; i++)

    info[i].mask |= mask;

      }

      else

      {

  unsigned cluster = _infos_find_min_cluster (info, idx, end);

  cluster = _infos_find_min_cluster (out_info, start, out_len, cluster);

  _infos_set_glyph_flags (out_info, start, out_len, cluster, mask);

  _infos_set_glyph_flags (info, idx, end, cluster, mask);

      }

    }

  }

  HB_ALWAYS_INLINE

  void _set_glyph_flags (hb_mask_t mask,

       unsigned start = 0,

       unsigned end = (unsigned) -1,

       bool interior = false,

       bool from_out_buffer = false)

  {

    if (unlikely (end != (unsigned) -1 && end - start > 255))

      return;

    end = hb_min (end, len);

    if (interior && !from_out_buffer && end - start < 2)

      return;

    _set_glyph_flags_impl (mask, start, end, interior, from_out_buffer);

  }

  void unsafe_to_break (unsigned int start = 0, unsigned int end = -1)

  {

    _set_glyph_flags (HB_GLYPH_FLAG_UNSAFE_TO_BREAK | HB_GLYPH_FLAG_UNSAFE_TO_CONCAT,

          start, end,

          true);

  }

  void safe_to_insert_tatweel (unsigned int start = 0, unsigned int end = -1)

  {

    if ((flags & HB_BUFFER_FLAG_PRODUCE_SAFE_TO_INSERT_TATWEEL) == 0)

    {

      unsafe_to_break (start, end);

      return;

    }

    _set_glyph_flags (HB_GLYPH_FLAG_SAFE_TO_INSERT_TATWEEL,

          start, end,

          true);

  }

#ifndef HB_OPTIMIZE_SIZE

  HB_ALWAYS_INLINE

#endif

  void unsafe_to_concat (unsigned int start = 0, unsigned int end = -1)

  {

    if (likely ((flags & HB_BUFFER_FLAG_PRODUCE_UNSAFE_TO_CONCAT) == 0))

      return;

    _set_glyph_flags (HB_GLYPH_FLAG_UNSAFE_TO_CONCAT,

          start, end,

          false);

  }

  void unsafe_to_break_from_outbuffer (unsigned int start = 0, unsigned int end = -1)

  {

    _set_glyph_flags (HB_GLYPH_FLAG_UNSAFE_TO_BREAK | HB_GLYPH_FLAG_UNSAFE_TO_CONCAT,

          start, end,

          true, true);

  }

#ifndef HB_OPTIMIZE_SIZE

  HB_ALWAYS_INLINE

#endif

  void unsafe_to_concat_from_outbuffer (unsigned int start = 0, unsigned int end = -1)

  {

    if (likely ((flags & HB_BUFFER_FLAG_PRODUCE_UNSAFE_TO_CONCAT) == 0))

      return;

    _set_glyph_flags (HB_GLYPH_FLAG_UNSAFE_TO_CONCAT,

          start, end,

          false, true);

  }

  /* Internal methods */

  HB_NODISCARD HB_INTERNAL bool move_to (unsigned int i); /* i is output-buffer index. */

  HB_NODISCARD HB_INTERNAL bool enlarge (unsigned int size);

  HB_NODISCARD bool resize (unsigned length)

  {

    assert (!have_output);

    if (unlikely (!ensure (length))) return false;

    len = length;

    return true;

  }

  HB_NODISCARD bool ensure (unsigned int size)

  { return likely (!size || size < allocated) ? true : enlarge (size); }

  HB_NODISCARD bool ensure_inplace (unsigned int size)

  { return likely (!size || size < allocated); }

  void assert_glyphs ()

  {

    assert ((content_type == HB_BUFFER_CONTENT_TYPE_GLYPHS) ||

      (!len && (content_type == HB_BUFFER_CONTENT_TYPE_INVALID)));

  }

  void assert_unicode ()

  {

    assert ((content_type == HB_BUFFER_CONTENT_TYPE_UNICODE) ||

      (!len && (content_type == HB_BUFFER_CONTENT_TYPE_INVALID)));

  }

  HB_NODISCARD bool ensure_glyphs ()

  {

    if (unlikely (content_type != HB_BUFFER_CONTENT_TYPE_GLYPHS))

    {

      if (content_type != HB_BUFFER_CONTENT_TYPE_INVALID)

  return false;

      assert (len == 0);

      content_type = HB_BUFFER_CONTENT_TYPE_GLYPHS;

    }

    return true;

  }

  HB_NODISCARD bool ensure_unicode ()

  {

    if (unlikely (content_type != HB_BUFFER_CONTENT_TYPE_UNICODE))

    {

      if (content_type != HB_BUFFER_CONTENT_TYPE_INVALID)

  return false;

      assert (len == 0);

      content_type = HB_BUFFER_CONTENT_TYPE_UNICODE;

    }

    return true;

  }

  HB_NODISCARD HB_INTERNAL bool make_room_for (unsigned int num_in, unsigned int num_out);

  HB_NODISCARD HB_INTERNAL bool shift_forward (unsigned int count);

  typedef long scratch_buffer_t;

  HB_INTERNAL scratch_buffer_t *get_scratch_buffer (unsigned int *size);

  void clear_context (unsigned int side) { context_len[side] = 0; }

  HB_INTERNAL void sort (unsigned int start, unsigned int end, int(*compar)(const hb_glyph_info_t *, const hb_glyph_info_t *));

  bool messaging ()

  {

#ifdef HB_NO_BUFFER_MESSAGE

    return false;

#else

    return unlikely (message_func);

#endif

  }

  bool message (hb_font_t *font, const char *fmt, ...) HB_PRINTF_FUNC(3, 4)

  {

#ifdef HB_NO_BUFFER_MESSAGE

    return true;

#else

    if (likely (!messaging ()))

      return true;

    va_list ap;

    va_start (ap, fmt);

    bool ret = message_impl (font, fmt, ap);

    va_end (ap);

    return ret;

#endif

  }

  HB_INTERNAL bool message_impl (hb_font_t *font, const char *fmt, va_list ap) HB_PRINTF_FUNC(3, 0);

  HB_INTERNAL void changed ();

  static void

  set_cluster (hb_glyph_info_t &inf, unsigned int cluster, unsigned int mask = 0)

  {

    if (inf.cluster != cluster)

      inf.mask = (inf.mask & ~HB_GLYPH_FLAG_DEFINED) | (mask & HB_GLYPH_FLAG_DEFINED);

    inf.cluster = cluster;

  }

  void

  _infos_set_glyph_flags (hb_glyph_info_t *infos,

        unsigned int start, unsigned int end,

        unsigned int cluster,

        hb_mask_t mask)

  {

    if (unlikely (start == end))

      return;

    max_ops -= end - start;

    if (unlikely (max_ops < 0))

      successful = false;

    unsigned cluster_first = infos[start].cluster;

    unsigned cluster_last = infos[end - 1].cluster;

    if (cluster_level == HB_BUFFER_CLUSTER_LEVEL_CHARACTERS ||

  (cluster != cluster_first && cluster != cluster_last))

    {

      for (unsigned int i = start; i < end; i++)

  if (cluster != infos[i].cluster)

    infos[i].mask |= mask;

      return;

    }

    /* Monotone clusters */

    if (cluster == cluster_first)

    {

      for (unsigned int i = end; start < i && infos[i - 1].cluster != cluster_first; i--)

  infos[i - 1].mask |= mask;

    }

    else /* cluster == cluster_last */

    {

      for (unsigned int i = start; i < end && infos[i].cluster != cluster_last; i++)

  infos[i].mask |= mask;

    }

  }

  unsigned

  _infos_find_min_cluster (const hb_glyph_info_t *infos,

         unsigned start, unsigned end,

         unsigned cluster = UINT_MAX)

  {

    if (unlikely (start == end))

      return cluster;

    if (cluster_level == HB_BUFFER_CLUSTER_LEVEL_CHARACTERS)

    {

      for (unsigned int i = start; i < end; i++)

  cluster = hb_min (cluster, infos[i].cluster);

      return cluster;

    }

    return hb_min (cluster, hb_min (infos[start].cluster, infos[end - 1].cluster));

  }

  void clear_glyph_flags (hb_mask_t mask = 0)

  {

    for (unsigned int i = 0; i < len; i++)

      info[i].mask = (info[i].mask & ~HB_GLYPH_FLAG_DEFINED) | (mask & HB_GLYPH_FLAG_DEFINED);

  }

};

DECLARE_NULL_INSTANCE (hb_buffer_t);

#define foreach_group(buffer, start, end, group_func) \

  for (unsigned int \

       _count = buffer->len, \

       start = 0, end = _count ? buffer->group_end (0, group_func) : 0; \

       start < _count; \

       start = end, end = buffer->group_end (start, group_func))

#define foreach_cluster(buffer, start, end) \

  foreach_group (buffer, start, end, hb_buffer_t::_cluster_group_func)

#define HB_BUFFER_XALLOCATE_VAR(b, func, var) \

  b->func (offsetof (hb_glyph_info_t, var) - offsetof(hb_glyph_info_t, var1), \

     sizeof (b->info[0].var))

#define HB_BUFFER_ALLOCATE_VAR(b, var)    HB_BUFFER_XALLOCATE_VAR (b, allocate_var,     var ())

#define HB_BUFFER_TRY_ALLOCATE_VAR(b, var)  HB_BUFFER_XALLOCATE_VAR (b, try_allocate_var, var ())

#define HB_BUFFER_DEALLOCATE_VAR(b, var)  HB_BUFFER_XALLOCATE_VAR (b, deallocate_var,   var ())

#define HB_BUFFER_ASSERT_VAR(b, var)    HB_BUFFER_XALLOCATE_VAR (b, assert_var,       var ())

#endif /* HB_BUFFER_HH */