Update harfbuzz-ng to 1a5a91dc0d8bf4b72a2f22dc6300b06ad7000b79.

third_party/harfbuzz-ng/src/hb-buffer.cc

 /*
- * Copyright (C) 1998-2004  David Turner and Werner Lemberg
- * Copyright (C) 2004,2007,2009,2010  Red Hat, Inc.
+ * Copyright © 1998-2004  David Turner and Werner Lemberg
+ * Copyright © 2004,2007,2009,2010  Red Hat, Inc.
+ * Copyright © 2011  Google, Inc.
  *
- * This is part of HarfBuzz, a text shaping library.
+ *  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
  */
 
 #include "hb-buffer-private.hh"
 
 #include <string.h>
 
-HB_BEGIN_DECLS
+
+
+#ifndef HB_DEBUG_BUFFER
+#define HB_DEBUG_BUFFER (HB_DEBUG+0)
+#endif
 
 
 static hb_buffer_t _hb_buffer_nil = {
-  HB_REFERENCE_COUNT_INVALID, /* ref_count */
+  HB_OBJECT_HEADER_STATIC,
 
-  &_hb_unicode_funcs_nil  /* unicode */
+  &_hb_unicode_funcs_default,
+  {
+    HB_DIRECTION_INVALID,
+    HB_SCRIPT_INVALID,
+    NULL,
+  },
+
+  TRUE, /* in_error */
+  TRUE, /* have_output */
+  TRUE  /* have_positions */
 };
 
 /* Here is how the buffer works internally:
  *
  * There are two info pointers: info and out_info.  They always have
  * the same allocated size, but different lengths.
  *
  * As an optimization, both info and out_info may point to the
  * same piece of memory, which is owned by info.  This remains the
- * case as long as out_len doesn't exceed len at any time.
- * In that case, swap() is no-op and the glyph operations operate
+ * case as long as out_len doesn't exceed i at any time.
+ * In that case, swap_buffers() is no-op and the glyph operations operate
  * mostly in-place.
  *
  * As soon as out_info gets longer than info, out_info is moved over
  * to an alternate buffer (which we reuse the pos buffer for!), and its
  * current contents (out_len entries) are copied to the new place.
- * This should all remain transparent to the user.  swap() then
+ * This should all remain transparent to the user.  swap_buffers() then
  * switches info and out_info.
  */
 
 
-static hb_bool_t
-_hb_buffer_enlarge (hb_buffer_t *buffer, unsigned int size)
-{
-  if (unlikely (buffer->in_error))
+
+/* Internal API */
+
+bool
+hb_buffer_t::enlarge (unsigned int size)
+{
+  if (unlikely (in_error))
     return FALSE;
 
-  unsigned int new_allocated = buffer->allocated;
-  hb_glyph_position_t *new_pos;
-  hb_glyph_info_t *new_info;
-  bool separate_out;
-
-  separate_out = buffer->out_info != buffer->info;
+  unsigned int new_allocated = allocated;
+  hb_glyph_position_t *new_pos = NULL;
+  hb_glyph_info_t *new_info = NULL;
+  bool separate_out = out_info != info;
+
+  if (unlikely (_hb_unsigned_int_mul_overflows (size, sizeof (info[0]))))
+    goto done;
 
   while (size > new_allocated)
-    new_allocated += (new_allocated >> 1) + 8;
-
-  new_pos = (hb_glyph_position_t *) realloc (buffer->pos, new_allocated * sizeof (buffer->pos[0]));
-  new_info = (hb_glyph_info_t *) realloc (buffer->info, new_allocated * sizeof (buffer->info[0]));
-
+    new_allocated += (new_allocated >> 1) + 32;
+
+  ASSERT_STATIC (sizeof (info[0]) == sizeof (pos[0]));
+  if (unlikely (_hb_unsigned_int_mul_overflows (new_allocated, sizeof (info[0]))))
+    goto done;
+
+  new_pos = (hb_glyph_position_t *) realloc (pos, new_allocated * sizeof (pos[0]));
+  new_info = (hb_glyph_info_t *) realloc (info, new_allocated * sizeof (info[0]));
+
+done:
   if (unlikely (!new_pos || !new_info))
-    buffer->in_error = TRUE;
+    in_error = TRUE;
 
   if (likely (new_pos))
-    buffer->pos = new_pos;
+    pos = new_pos;
 
   if (likely (new_info))
-    buffer->info = new_info;
-
-  buffer->out_info = separate_out ? (hb_glyph_info_t *) buffer->pos : buffer->info;
-  if (likely (!buffer->in_error))
-    buffer->allocated = new_allocated;
-
-  return likely (!buffer->in_error);
-}
-
-static inline hb_bool_t
-_hb_buffer_ensure (hb_buffer_t *buffer, unsigned int size)
-{
-  return likely (size <= buffer->allocated) ? TRUE : _hb_buffer_enlarge (buffer, size);
-}
-
-static inline hb_bool_t
-_hb_buffer_ensure_separate (hb_buffer_t *buffer, unsigned int size)
-{
-  if (unlikely (!_hb_buffer_ensure (buffer, size))) return FALSE;
-
-  if (buffer->out_info == buffer->info)
+    info = new_info;
+
+  out_info = separate_out ? (hb_glyph_info_t *) pos : info;
+  if (likely (!in_error))
+    allocated = new_allocated;
+
+  return likely (!in_error);
+}
+
+bool
+hb_buffer_t::make_room_for (unsigned int num_in,
+                            unsigned int num_out)
+{
+  if (unlikely (!ensure (out_len + num_out))) return FALSE;
+
+  if (out_info == info &&
+      out_len + num_out > idx + num_in)
   {
-    assert (buffer->have_output);
-
-    buffer->out_info = (hb_glyph_info_t *) buffer->pos;
-    memcpy (buffer->out_info, buffer->info, buffer->out_len * sizeof (buffer->out_info[0]));
+    assert (have_output);
+
+    out_info = (hb_glyph_info_t *) pos;
+    memcpy (out_info, info, out_len * sizeof (out_info[0]));
   }
 
   return TRUE;
 }
 
-
-/* Public API */
-
-hb_buffer_t *
-hb_buffer_create (unsigned int pre_alloc_size)
-{
-  hb_buffer_t *buffer;
-
-  if (!HB_OBJECT_DO_CREATE (hb_buffer_t, buffer))
-    return &_hb_buffer_nil;
-
-  if (pre_alloc_size)
-    _hb_buffer_ensure (buffer, pre_alloc_size);
-
-  buffer->unicode = &_hb_unicode_funcs_nil;
-
-  return buffer;
-}
-
-hb_buffer_t *
-hb_buffer_reference (hb_buffer_t *buffer)
-{
-  HB_OBJECT_DO_REFERENCE (buffer);
-}
-
-unsigned int
-hb_buffer_get_reference_count (hb_buffer_t *buffer)
-{
-  HB_OBJECT_DO_GET_REFERENCE_COUNT (buffer);
-}
-
-void
-hb_buffer_destroy (hb_buffer_t *buffer)
-{
-  HB_OBJECT_DO_DESTROY (buffer);
-
-  hb_unicode_funcs_destroy (buffer->unicode);
-
-  free (buffer->info);
-  free (buffer->pos);
-
-  free (buffer);
-}
-
-
-void
-hb_buffer_set_unicode_funcs (hb_buffer_t        *buffer,
-                             hb_unicode_funcs_t *unicode)
-{
-  if (!unicode)
-    unicode = &_hb_unicode_funcs_nil;
-
-  hb_unicode_funcs_reference (unicode);
-  hb_unicode_funcs_destroy (buffer->unicode);
-  buffer->unicode = unicode;
-}
-
-hb_unicode_funcs_t *
-hb_buffer_get_unicode_funcs (hb_buffer_t        *buffer)
-{
-  return buffer->unicode;
-}
-
-void
-hb_buffer_set_direction (hb_buffer_t    *buffer,
-                         hb_direction_t  direction)
-
-{
-  buffer->props.direction = direction;
-}
-
-hb_direction_t
-hb_buffer_get_direction (hb_buffer_t    *buffer)
-{
-  return buffer->props.direction;
-}
-
-void
-hb_buffer_set_script (hb_buffer_t *buffer,
-                      hb_script_t  script)
-{
-  buffer->props.script = script;
-}
-
-hb_script_t
-hb_buffer_get_script (hb_buffer_t *buffer)
-{
-  return buffer->props.script;
-}
-
-void
-hb_buffer_set_language (hb_buffer_t   *buffer,
-                        hb_language_t  language)
-{
-  buffer->props.language = language;
-}
-
-hb_language_t
-hb_buffer_get_language (hb_buffer_t *buffer)
-{
-  return buffer->props.language;
-}
-
-
-void
-hb_buffer_clear (hb_buffer_t *buffer)
-{
-  buffer->have_output = FALSE;
-  buffer->have_positions = FALSE;
-  buffer->in_error = FALSE;
-  buffer->len = 0;
-  buffer->out_len = 0;
-  buffer->i = 0;
-  buffer->out_info = buffer->info;
-  buffer->serial = 0;
-}
-
-hb_bool_t
-hb_buffer_ensure (hb_buffer_t *buffer, unsigned int size)
-{
-  return _hb_buffer_ensure (buffer, size);
-}
-
-void
-hb_buffer_add_glyph (hb_buffer_t    *buffer,
-                     hb_codepoint_t  codepoint,
-                     hb_mask_t       mask,
-                     unsigned int    cluster)
+void *
+hb_buffer_t::get_scratch_buffer (unsigned int *size)
+{
+  have_output = FALSE;
+  have_positions = FALSE;
+  out_len = 0;
+  *size = allocated * sizeof (pos[0]);
+  return pos;
+}
+
+
+/* HarfBuzz-Internal API */
+
+void
+hb_buffer_t::reset (void)
+{
+  if (unlikely (hb_object_is_inert (this)))
+    return;
+
+  hb_unicode_funcs_destroy (unicode);
+  unicode = _hb_buffer_nil.unicode;
+
+  props = _hb_buffer_nil.props;
+
+  in_error = FALSE;
+  have_output = FALSE;
+  have_positions = FALSE;
+
+  idx = 0;
+  len = 0;
+  out_len = 0;
+
+  serial = 0;
+  memset (allocated_var_bytes, 0, sizeof allocated_var_bytes);
+  memset (allocated_var_owner, 0, sizeof allocated_var_owner);
+
+  out_info = info;
+}
+
+void
+hb_buffer_t::add (hb_codepoint_t  codepoint,
+                  hb_mask_t       mask,
+                  unsigned int    cluster)
 {
   hb_glyph_info_t *glyph;
 
-  if (unlikely (!_hb_buffer_ensure (buffer, buffer->len + 1))) return;
-
-  glyph = &buffer->info[buffer->len];
+  if (unlikely (!ensure (len + 1))) return;
+
+  glyph = &info[len];
 
   memset (glyph, 0, sizeof (*glyph));
   glyph->codepoint = codepoint;
   glyph->mask = mask;
   glyph->cluster = cluster;
 
-  buffer->len++;
-}
-
-void
-hb_buffer_clear_positions (hb_buffer_t *buffer)
-{
-  _hb_buffer_clear_output (buffer);
-  buffer->have_output = FALSE;
-  buffer->have_positions = TRUE;
-
-  if (unlikely (!buffer->pos))
-  {
-    buffer->pos = (hb_glyph_position_t *) calloc (buffer->allocated, sizeof (buffer->pos[0]));
-    return;
-  }
-
-  memset (buffer->pos, 0, sizeof (buffer->pos[0]) * buffer->len);
-}
-
-/* HarfBuzz-Internal API */
-
-void
-_hb_buffer_clear_output (hb_buffer_t *buffer)
-{
-  buffer->have_output = TRUE;
-  buffer->have_positions = FALSE;
-  buffer->out_len = 0;
-  buffer->out_info = buffer->info;
-}
-
-void
-_hb_buffer_swap (hb_buffer_t *buffer)
-{
-  unsigned int tmp;
-
-  assert (buffer->have_output);
-
-  if (unlikely (buffer->in_error)) return;
-
-  if (buffer->out_info != buffer->info)
+  len++;
+}
+
+void
+hb_buffer_t::clear_output (void)
+{
+  if (unlikely (hb_object_is_inert (this)))
+    return;
+
+  have_output = TRUE;
+  have_positions = FALSE;
+
+  out_len = 0;
+  out_info = info;
+}
+
+void
+hb_buffer_t::clear_positions (void)
+{
+  if (unlikely (hb_object_is_inert (this)))
+    return;
+
+  have_output = FALSE;
+  have_positions = TRUE;
+
+  memset (pos, 0, sizeof (pos[0]) * len);
+}
+
+void
+hb_buffer_t::swap_buffers (void)
+{
+  if (unlikely (in_error)) return;
+
+  assert (have_output);
+
+  if (out_info != info)
   {
     hb_glyph_info_t *tmp_string;
-    tmp_string = buffer->info;
-    buffer->info = buffer->out_info;
-    buffer->out_info = tmp_string;
-    buffer->pos = (hb_glyph_position_t *) buffer->out_info;
-  }
-
-  tmp = buffer->len;
-  buffer->len = buffer->out_len;
-  buffer->out_len = tmp;
-
-  buffer->i = 0;
-}
-
-void
-_hb_buffer_replace_glyphs_be16 (hb_buffer_t *buffer,
-                                unsigned int num_in,
-                                unsigned int num_out,
-                                const uint16_t *glyph_data_be)
-{
-  if (buffer->out_info != buffer->info ||
-      buffer->out_len + num_out > buffer->i + num_in)
+    tmp_string = info;
+    info = out_info;
+    out_info = tmp_string;
+    pos = (hb_glyph_position_t *) out_info;
+  }
+
+  unsigned int tmp;
+  tmp = len;
+  len = out_len;
+  out_len = tmp;
+
+  idx = 0;
+}
+
+void
+hb_buffer_t::replace_glyphs_be16 (unsigned int num_in,
+                                  unsigned int num_out,
+                                  const uint16_t *glyph_data_be)
+{
+  if (!make_room_for (num_in, num_out)) return;
+
+  hb_glyph_info_t orig_info = info[idx];
+  for (unsigned int i = 1; i < num_in; i++)
   {
-    if (unlikely (!_hb_buffer_ensure_separate (buffer, buffer->out_len + num_out)))
-      return;
-  }
-
-  hb_glyph_info_t orig_info = buffer->info[buffer->i];
-
+    hb_glyph_info_t *inf = &info[idx + i];
+    orig_info.cluster = MIN (orig_info.cluster, inf->cluster);
+  }
+
+  hb_glyph_info_t *pinfo = &out_info[out_len];
   for (unsigned int i = 0; i < num_out; i++)
   {
-    hb_glyph_info_t *info = &buffer->out_info[buffer->out_len + i];
-    *info = orig_info;
-    info->codepoint = hb_be_uint16 (glyph_data_be[i]);
-  }
-
-  buffer->i  += num_in;
-  buffer->out_len += num_out;
-}
-
-void
-_hb_buffer_replace_glyph (hb_buffer_t *buffer,
-                          hb_codepoint_t glyph_index)
-{
-  hb_glyph_info_t *info;
-
-  if (buffer->out_info != buffer->info)
+    *pinfo = orig_info;
+    pinfo->codepoint = hb_be_uint16 (glyph_data_be[i]);
+    pinfo++;
+  }
+
+  idx  += num_in;
+  out_len += num_out;
+}
+
+void
+hb_buffer_t::replace_glyphs (unsigned int num_in,
+                             unsigned int num_out,
+                             const uint16_t *glyph_data)
+{
+  if (!make_room_for (num_in, num_out)) return;
+
+  hb_glyph_info_t orig_info = info[idx];
+  for (unsigned int i = 1; i < num_in; i++)
   {
-    if (unlikely (!_hb_buffer_ensure (buffer, buffer->out_len + 1))) return;
-    buffer->out_info[buffer->out_len] = buffer->info[buffer->i];
-  }
-  else if (buffer->out_len != buffer->i)
-    buffer->out_info[buffer->out_len] = buffer->info[buffer->i];
-
-  info = &buffer->out_info[buffer->out_len];
-  info->codepoint = glyph_index;
-
-  buffer->i++;
-  buffer->out_len++;
-}
-
-void
-_hb_buffer_next_glyph (hb_buffer_t *buffer)
-{
-  if (buffer->have_output)
+    hb_glyph_info_t *inf = &info[idx + i];
+    orig_info.cluster = MIN (orig_info.cluster, inf->cluster);
+  }
+
+  hb_glyph_info_t *pinfo = &out_info[out_len];
+  for (unsigned int i = 0; i < num_out; i++)
   {
-    if (buffer->out_info != buffer->info)
+    *pinfo = orig_info;
+    pinfo->codepoint = glyph_data[i];
+    pinfo++;
+  }
+
+  idx  += num_in;
+  out_len += num_out;
+}
+
+void
+hb_buffer_t::output_glyph (hb_codepoint_t glyph_index)
+{
+  if (!make_room_for (0, 1)) return;
+
+  out_info[out_len] = info[idx];
+  out_info[out_len].codepoint = glyph_index;
+
+  out_len++;
+}
+
+void
+hb_buffer_t::copy_glyph (void)
+{
+  if (!make_room_for (0, 1)) return;
+
+  out_info[out_len] = info[idx];
+
+  out_len++;
+}
+
+void
+hb_buffer_t::replace_glyph (hb_codepoint_t glyph_index)
+{
+  if (!make_room_for (1, 1)) return;
+
+  out_info[out_len] = info[idx];
+  out_info[out_len].codepoint = glyph_index;
+
+  idx++;
+  out_len++;
+}
+
+void
+hb_buffer_t::next_glyph (void)
+{
+  if (have_output)
+  {
+    if (out_info != info)
     {
-      if (unlikely (!_hb_buffer_ensure (buffer, buffer->out_len + 1))) return;
-      buffer->out_info[buffer->out_len] = buffer->info[buffer->i];
+      if (unlikely (!ensure (out_len + 1))) return;
+      out_info[out_len] = info[idx];
     }
-    else if (buffer->out_len != buffer->i)
-      buffer->out_info[buffer->out_len] = buffer->info[buffer->i];
-
-    buffer->out_len++;
-  }
-
-  buffer->i++;
-}
-
-void
-_hb_buffer_reset_masks (hb_buffer_t *buffer,
-                        hb_mask_t    mask)
-{
-  unsigned int count = buffer->len;
-  for (unsigned int i = 0; i < count; i++)
-    buffer->info[i].mask = mask;
-}
-
-void
-_hb_buffer_add_masks (hb_buffer_t *buffer,
-                      hb_mask_t    mask)
-{
-  unsigned int count = buffer->len;
-  for (unsigned int i = 0; i < count; i++)
-    buffer->info[i].mask |= mask;
-}
-
-void
-_hb_buffer_set_masks (hb_buffer_t *buffer,
-                      hb_mask_t    value,
-                      hb_mask_t    mask,
-                      unsigned int cluster_start,
-                      unsigned int cluster_end)
+    else if (out_len != idx)
+      out_info[out_len] = info[idx];
+
+    out_len++;
+  }
+
+  idx++;
+}
+
+void
+hb_buffer_t::set_masks (hb_mask_t    value,
+                        hb_mask_t    mask,
+                        unsigned int cluster_start,
+                        unsigned int cluster_end)
 {
   hb_mask_t not_mask = ~mask;
   value &= mask;
 
   if (!mask)
     return;
 
   if (cluster_start == 0 && cluster_end == (unsigned int)-1) {
-    unsigned int count = buffer->len;
+    unsigned int count = len;
     for (unsigned int i = 0; i < count; i++)
-      buffer->info[i].mask = (buffer->info[i].mask & not_mask) | value;
-    return;
-  }
-
-  /* XXX can't bsearch since .cluster may not be sorted. */
-  /* Binary search to find the start position and go from there. */
-  unsigned int min = 0, max = buffer->len;
-  while (min < max)
-  {
-    unsigned int mid = min + ((max - min) / 2);
-    if (buffer->info[mid].cluster < cluster_start)
-      min = mid + 1;
-    else
-      max = mid;
-  }
-  unsigned int count = buffer->len;
-  for (unsigned int i = min; i < count && buffer->info[i].cluster < cluster_end; i++)
-    buffer->info[i].mask = (buffer->info[i].mask & not_mask) | value;
-}
-
-
-/* Public API again */
+      info[i].mask = (info[i].mask & not_mask) | value;
+    return;
+  }
+
+  unsigned int count = len;
+  for (unsigned int i = 0; i < count; i++)
+    if (cluster_start <= info[i].cluster && info[i].cluster < cluster_end)
+      info[i].mask = (info[i].mask & not_mask) | value;
+}
+
+void
+hb_buffer_t::reverse_range (unsigned int start,
+                            unsigned int end)
+{
+  unsigned int i, j;
+
+  if (start == end - 1)
+    return;
+
+  for (i = start, j = end - 1; i < j; i++, j--) {
+    hb_glyph_info_t t;
+
+    t = info[i];
+    info[i] = info[j];
+    info[j] = t;
+  }
+
+  if (pos) {
+    for (i = start, j = end - 1; i < j; i++, j--) {
+      hb_glyph_position_t t;
+
+      t = pos[i];
+      pos[i] = pos[j];
+      pos[j] = t;
+    }
+  }
+}
+
+void
+hb_buffer_t::reverse (void)
+{
+  if (unlikely (!len))
+    return;
+
+  reverse_range (0, len);
+}
+
+void
+hb_buffer_t::reverse_clusters (void)
+{
+  unsigned int i, start, count, last_cluster;
+
+  if (unlikely (!len))
+    return;
+
+  reverse ();
+
+  count = len;
+  start = 0;
+  last_cluster = info[0].cluster;
+  for (i = 1; i < count; i++) {
+    if (last_cluster != info[i].cluster) {
+      reverse_range (start, i);
+      start = i;
+      last_cluster = info[i].cluster;
+    }
+  }
+  reverse_range (start, i);
+}
+
+void
+hb_buffer_t::guess_properties (void)
+{
+  /* If script is set to INVALID, guess from buffer contents */
+  if (props.script == HB_SCRIPT_INVALID) {
+    for (unsigned int i = 0; i < len; i++) {
+      hb_script_t script = hb_unicode_script (unicode, info[i].codepoint);
+      if (likely (script != HB_SCRIPT_COMMON &&
+                  script != HB_SCRIPT_INHERITED &&
+                  script != HB_SCRIPT_UNKNOWN)) {
+        props.script = script;
+        break;
+      }
+    }
+  }
+
+  /* If direction is set to INVALID, guess from script */
+  if (props.direction == HB_DIRECTION_INVALID) {
+    props.direction = hb_script_get_horizontal_direction (props.script);
+  }
+
+  /* If language is not set, use default language from locale */
+  if (props.language == HB_LANGUAGE_INVALID) {
+    /* TODO get_default_for_script? using $LANGUAGE */
+    props.language = hb_language_get_default ();
+  }
+}
+
+
+static inline void
+dump_var_allocation (const hb_buffer_t *buffer)
+{
+  char buf[80];
+  for (unsigned int i = 0; i < 8; i++)
+    buf[i] = '0' + buffer->allocated_var_bytes[7 - i];
+  buf[8] = '\0';
+  DEBUG_MSG (BUFFER, buffer,
+             "Current var allocation: %s",
+             buf);
+}
+
+void hb_buffer_t::allocate_var (unsigned int byte_i, unsigned int count, const char *owner)
+{
+  assert (byte_i < 8 && byte_i + count <= 8);
+
+  if (DEBUG (BUFFER))
+    dump_var_allocation (this);
+  DEBUG_MSG (BUFFER, this,
+             "Allocating var bytes %d..%d for %s",
+             byte_i, byte_i + count - 1, owner);
+
+  for (unsigned int i = byte_i; i < byte_i + count; i++) {
+    assert (!allocated_var_bytes[i]);
+    allocated_var_bytes[i]++;
+    allocated_var_owner[i] = owner;
+  }
+}
+
+void hb_buffer_t::deallocate_var (unsigned int byte_i, unsigned int count, const char *owner)
+{
+  if (DEBUG (BUFFER))
+    dump_var_allocation (this);
+
+  DEBUG_MSG (BUFFER, this,
+             "Deallocating var bytes %d..%d for %s",
+             byte_i, byte_i + count - 1, owner);
+
+  assert (byte_i < 8 && byte_i + count <= 8);
+  for (unsigned int i = byte_i; i < byte_i + count; i++) {
+    assert (allocated_var_bytes[i]);
+    assert (0 == strcmp (allocated_var_owner[i], owner));
+    allocated_var_bytes[i]--;
+  }
+}
+
+void hb_buffer_t::deallocate_var_all (void)
+{
+  memset (allocated_var_bytes, 0, sizeof (allocated_var_bytes));
+  memset (allocated_var_owner, 0, sizeof (allocated_var_owner));
+}
+
+/* Public API */
+
+hb_buffer_t *
+hb_buffer_create ()
+{
+  hb_buffer_t *buffer;
+
+  if (!(buffer = hb_object_create<hb_buffer_t> ()))
+    return &_hb_buffer_nil;
+
+  buffer->reset ();
+
+  return buffer;
+}
+
+hb_buffer_t *
+hb_buffer_get_empty (void)
+{
+  return &_hb_buffer_nil;
+}
+
+hb_buffer_t *
+hb_buffer_reference (hb_buffer_t *buffer)
+{
+  return hb_object_reference (buffer);
+}
+
+void
+hb_buffer_destroy (hb_buffer_t *buffer)
+{
+  if (!hb_object_destroy (buffer)) return;
+
+  hb_unicode_funcs_destroy (buffer->unicode);
+
+  free (buffer->info);
+  free (buffer->pos);
+
+  free (buffer);
+}
+
+hb_bool_t
+hb_buffer_set_user_data (hb_buffer_t        *buffer,
+                         hb_user_data_key_t *key,
+                         void *              data,
+                         hb_destroy_func_t   destroy,
+                         hb_bool_t           replace)
+{
+  return hb_object_set_user_data (buffer, key, data, destroy, replace);
+}
+
+void *
+hb_buffer_get_user_data (hb_buffer_t        *buffer,
+                         hb_user_data_key_t *key)
+{
+  return hb_object_get_user_data (buffer, key);
+}
+
+
+void
+hb_buffer_set_unicode_funcs (hb_buffer_t        *buffer,
+                             hb_unicode_funcs_t *unicode)
+{
+  if (unlikely (hb_object_is_inert (buffer)))
+    return;
+
+  if (!unicode)
+    unicode = _hb_buffer_nil.unicode;
+
+  hb_unicode_funcs_reference (unicode);
+  hb_unicode_funcs_destroy (buffer->unicode);
+  buffer->unicode = unicode;
+}
+
+hb_unicode_funcs_t *
+hb_buffer_get_unicode_funcs (hb_buffer_t        *buffer)
+{
+  return buffer->unicode;
+}
+
+void
+hb_buffer_set_direction (hb_buffer_t    *buffer,
+                         hb_direction_t  direction)
+
+{
+  if (unlikely (hb_object_is_inert (buffer)))
+    return;
+
+  buffer->props.direction = direction;
+}
+
+hb_direction_t
+hb_buffer_get_direction (hb_buffer_t    *buffer)
+{
+  return buffer->props.direction;
+}
+
+void
+hb_buffer_set_script (hb_buffer_t *buffer,
+                      hb_script_t  script)
+{
+  if (unlikely (hb_object_is_inert (buffer)))
+    return;
+
+  buffer->props.script = script;
+}
+
+hb_script_t
+hb_buffer_get_script (hb_buffer_t *buffer)
+{
+  return buffer->props.script;
+}
+
+void
+hb_buffer_set_language (hb_buffer_t   *buffer,
+                        hb_language_t  language)
+{
+  if (unlikely (hb_object_is_inert (buffer)))
+    return;
+
+  buffer->props.language = language;
+}
+
+hb_language_t
+hb_buffer_get_language (hb_buffer_t *buffer)
+{
+  return buffer->props.language;
+}
+
+
+void
+hb_buffer_reset (hb_buffer_t *buffer)
+{
+  buffer->reset ();
+}
+
+hb_bool_t
+hb_buffer_pre_allocate (hb_buffer_t *buffer, unsigned int size)
+{
+  return buffer->ensure (size);
+}
+
+hb_bool_t
+hb_buffer_allocation_successful (hb_buffer_t  *buffer)
+{
+  return !buffer->in_error;
+}
+
+void
+hb_buffer_add (hb_buffer_t    *buffer,
+               hb_codepoint_t  codepoint,
+               hb_mask_t       mask,
+               unsigned int    cluster)
+{
+  buffer->add (codepoint, mask, cluster);
+}
+
+hb_bool_t
+hb_buffer_set_length (hb_buffer_t  *buffer,
+                      unsigned int  length)
+{
+  if (!buffer->ensure (length))
+    return FALSE;
+
+  /* Wipe the new space */
+  if (length > buffer->len) {
+    memset (buffer->info + buffer->len, 0, sizeof (buffer->info[0]) * (length - buffer->len));
+    if (buffer->have_positions)
+      memset (buffer->pos + buffer->len, 0, sizeof (buffer->pos[0]) * (length - buffer->len));
+  }
+
+  buffer->len = length;
+  return TRUE;
+}
 
 unsigned int
 hb_buffer_get_length (hb_buffer_t *buffer)
 {
   return buffer->len;
 }
 
 /* Return value valid as long as buffer not modified */
 hb_glyph_info_t *
-hb_buffer_get_glyph_infos (hb_buffer_t *buffer)
+hb_buffer_get_glyph_infos (hb_buffer_t  *buffer,
+                           unsigned int *length)
 {
+  if (length)
+    *length = buffer->len;
+
   return (hb_glyph_info_t *) buffer->info;
 }
 
 /* Return value valid as long as buffer not modified */
 hb_glyph_position_t *
-hb_buffer_get_glyph_positions (hb_buffer_t *buffer)
+hb_buffer_get_glyph_positions (hb_buffer_t  *buffer,
+                               unsigned int *length)
 {
   if (!buffer->have_positions)
-    hb_buffer_clear_positions (buffer);
+    buffer->clear_positions ();
+
+  if (length)
+    *length = buffer->len;
 
   return (hb_glyph_position_t *) buffer->pos;
 }
 
-
-static void
-reverse_range (hb_buffer_t *buffer,
-               unsigned int start,
-               unsigned int end)
-{
-  unsigned int i, j;
-
-  for (i = start, j = end - 1; i < j; i++, j--) {
-    hb_glyph_info_t t;
-
-    t = buffer->info[i];
-    buffer->info[i] = buffer->info[j];
-    buffer->info[j] = t;
-  }
-
-  if (buffer->pos) {
-    for (i = 0, j = end - 1; i < j; i++, j--) {
-      hb_glyph_position_t t;
-
-      t = buffer->pos[i];
-      buffer->pos[i] = buffer->pos[j];
-      buffer->pos[j] = t;
-    }
-  }
-}
-
 void
 hb_buffer_reverse (hb_buffer_t *buffer)
 {
-  if (unlikely (!buffer->len))
-    return;
-
-  reverse_range (buffer, 0, buffer->len);
+  buffer->reverse ();
 }
 
 void
 hb_buffer_reverse_clusters (hb_buffer_t *buffer)
 {
-  unsigned int i, start, count, last_cluster;
-
-  if (unlikely (!buffer->len))
-    return;
-
-  hb_buffer_reverse (buffer);
-
-  count = buffer->len;
-  start = 0;
-  last_cluster = buffer->info[0].cluster;
-  for (i = 1; i < count; i++) {
-    if (last_cluster != buffer->info[i].cluster) {
-      reverse_range (buffer, start, i);
-      start = i;
-      last_cluster = buffer->info[i].cluster;
-    }
-  }
-  reverse_range (buffer, start, i);
+  buffer->reverse_clusters ();
 }
 
+void
+hb_buffer_guess_properties (hb_buffer_t *buffer)
+{
+  buffer->guess_properties ();
+}
 
 #define ADD_UTF(T) \
         HB_STMT_START { \
+          if (text_length == -1) { \
+            text_length = 0; \
+            const T *p = (const T *) text; \
+            while (*p) { \
+              text_length++; \
+              p++; \
+            } \
+          } \
+          if (item_length == -1) \
+            item_length = text_length - item_offset; \
+          buffer->ensure (buffer->len + item_length * sizeof (T) / 4); \
           const T *next = (const T *) text + item_offset; \
           const T *end = next + item_length; \
           while (next < end) { \
             hb_codepoint_t u; \
             const T *old_next = next; \
             next = UTF_NEXT (next, end, u); \
-            hb_buffer_add_glyph (buffer, u, 1,  old_next - (const T *) text); \
+            hb_buffer_add (buffer, u, 1,  old_next - (const T *) text); \
           } \
         } HB_STMT_END
 
 
 #define UTF8_COMPUTE(Char, Mask, Len) \
   if (Char < 128) { Len = 1; Mask = 0x7f; } \
   else if ((Char & 0xe0) == 0xc0) { Len = 2; Mask = 0x1f; } \
   else if ((Char & 0xf0) == 0xe0) { Len = 3; Mask = 0x0f; } \
   else if ((Char & 0xf8) == 0xf0) { Len = 4; Mask = 0x07; } \
   else Len = 0;
 
 static inline const uint8_t *
 hb_utf8_next (const uint8_t *text,
               const uint8_t *end,
               hb_codepoint_t *unicode)
 {
   uint8_t c = *text;
   unsigned int mask, len;
 
-  /* TODO check for overlong sequences?  also: optimize? */
+  /* TODO check for overlong sequences? */
 
   UTF8_COMPUTE (c, mask, len);
   if (unlikely (!len || (unsigned int) (end - text) < len)) {
     *unicode = -1;
     return text + 1;
   } else {
     hb_codepoint_t result;
     unsigned int i;
     result = c & mask;
     for (i = 1; i < len; i++)
       {
         if (unlikely ((text[i] & 0xc0) != 0x80))
           {
             *unicode = -1;
             return text + 1;
           }
         result <<= 6;
         result |= (text[i] & 0x3f);
       }
     *unicode = result;
     return text + len;
   }
 }
 
 void
 hb_buffer_add_utf8 (hb_buffer_t  *buffer,
                     const char   *text,
-                    unsigned int  text_length HB_UNUSED,
+                    int           text_length,
                     unsigned int  item_offset,
-                    unsigned int  item_length)
+                    int           item_length)
 {
 #define UTF_NEXT(S, E, U)       hb_utf8_next (S, E, &(U))
   ADD_UTF (uint8_t);
 #undef UTF_NEXT
 }
 
 static inline const uint16_t *
 hb_utf16_next (const uint16_t *text,
                const uint16_t *end,
                hb_codepoint_t *unicode)
 {
   uint16_t c = *text++;
 
   if (unlikely (c >= 0xd800 && c < 0xdc00)) {
     /* high surrogate */
     uint16_t l;
-    if (text < end && ((l = *text), unlikely (l >= 0xdc00 && l < 0xe000))) {
+    if (text < end && ((l = *text), likely (l >= 0xdc00 && l < 0xe000))) {
       /* low surrogate */
       *unicode = ((hb_codepoint_t) ((c) - 0xd800) * 0x400 + (l) - 0xdc00 + 0x10000);
        text++;
     } else
       *unicode = -1;
   } else
     *unicode = c;
 
   return text;
 }
 
 void
 hb_buffer_add_utf16 (hb_buffer_t    *buffer,
                      const uint16_t *text,
-                     unsigned int    text_length HB_UNUSED,
+                     int             text_length,
                      unsigned int    item_offset,
-                     unsigned int    item_length)
+                     int            item_length)
 {
 #define UTF_NEXT(S, E, U)       hb_utf16_next (S, E, &(U))
   ADD_UTF (uint16_t);
 #undef UTF_NEXT
 }
 
 void
 hb_buffer_add_utf32 (hb_buffer_t    *buffer,
                      const uint32_t *text,
-                     unsigned int    text_length HB_UNUSED,
+                     int             text_length,
                      unsigned int    item_offset,
-                     unsigned int    item_length)
+                     int             item_length)
 {
 #define UTF_NEXT(S, E, U)       ((U) = *(S), (S)+1)
   ADD_UTF (uint32_t);
 #undef UTF_NEXT
 }
 
 
-HB_END_DECLS