Roll HarfBuzz to 1.1.3

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

Index: third_party/harfbuzz-ng/src/hb-buffer.cc
diff --git a/third_party/harfbuzz-ng/src/hb-buffer.cc b/third_party/harfbuzz-ng/src/hb-buffer.cc
index 5c71734b9de9a1d61b8c36deb40f376a31cc8bcf..c731ed189fd78850a29d8f4bdf10f275c1793c96 100644
--- a/third_party/harfbuzz-ng/src/hb-buffer.cc
+++ b/third_party/harfbuzz-ng/src/hb-buffer.cc
@@ -35,8 +35,26 @@
 #define HB_DEBUG_BUFFER (HB_DEBUG+0)
 #endif
 
+/**
+ * SECTION: hb-buffer
+ * @title: Buffers
+ * @short_description: Input and output buffers
+ * @include: hb.h
+ *
+ * Buffers serve dual role in HarfBuzz; they hold the input characters that are
+ * passed hb_shape(), and after shaping they hold the output glyphs.
+ **/
 
 /**
+ * hb_segment_properties_equal:
+ * @a: first #hb_segment_properties_t to compare.
+ * @b: second #hb_segment_properties_t to compare.
+ *
+ * Checks the equality of two #hb_segment_properties_t's.
+ *
+ * Return value: (transfer full):
+ * %true if all properties of @a equal those of @b, false otherwise.
+ *
  * Since: 0.9.7
  **/
 hb_bool_t
@@ -52,6 +70,14 @@ hb_segment_properties_equal (const hb_segment_properties_t *a,
 }
 
 /**
+ * hb_segment_properties_hash:
+ * @p: #hb_segment_properties_t to hash.
+ *
+ * Creates a hash representing @p.
+ *
+ * Return value:
+ * A hash of @p.
+ *
  * Since: 0.9.7
  **/
 unsigned int
@@ -706,9 +732,14 @@ void hb_buffer_t::deallocate_var_all (void)
 /**
  * hb_buffer_create: (Xconstructor)
  *
- * 
+ * Creates a new #hb_buffer_t with all properties to defaults.
  *
- * Return value: (transfer full)
+ * Return value: (transfer full):
+ * A newly allocated #hb_buffer_t with a reference count of 1. The initial
+ * reference count should be released with hb_buffer_destroy() when you are done
+ * using the #hb_buffer_t. This function never returns %NULL. If memory cannot
+ * be allocated, a special #hb_buffer_t object will be returned on which
+ * hb_buffer_allocation_successful() returns %false.
  *
  * Since: 0.9.2
  **/
@@ -763,11 +794,13 @@ hb_buffer_get_empty (void)
 
 /**
  * hb_buffer_reference: (skip)
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  *
- * 
+ * Increases the reference count on @buffer by one. This prevents @buffer from
+ * being destroyed until a matching call to hb_buffer_destroy() is made.
  *
  * Return value: (transfer full):
+ * The referenced #hb_buffer_t.
  *
  * Since: 0.9.2
  **/
@@ -779,9 +812,11 @@ hb_buffer_reference (hb_buffer_t *buffer)
 
 /**
  * hb_buffer_destroy: (skip)
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  *
- * 
+ * Deallocate the @buffer.
+ * Decreases the reference count on @buffer by one. If the result is zero, then
+ * @buffer and all associated resources are freed. See hb_buffer_reference().
  *
  * Since: 0.9.2
  **/
@@ -794,13 +829,15 @@ hb_buffer_destroy (hb_buffer_t *buffer)
 
   free (buffer->info);
   free (buffer->pos);
+  if (buffer->message_destroy)
+    buffer->message_destroy (buffer->message_data);
 
   free (buffer);
 }
 
 /**
  * hb_buffer_set_user_data: (skip)
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  * @key: 
  * @data: 
  * @destroy: 
@@ -824,7 +861,7 @@ hb_buffer_set_user_data (hb_buffer_t        *buffer,
 
 /**
  * hb_buffer_get_user_data: (skip)
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  * @key: 
  *
  * 
@@ -843,10 +880,11 @@ hb_buffer_get_user_data (hb_buffer_t        *buffer,
 
 /**
  * hb_buffer_set_content_type:
- * @buffer: a buffer.
- * @content_type: 
+ * @buffer: an #hb_buffer_t.
+ * @content_type: the type of buffer contents to set
  *
- * 
+ * Sets the type of @buffer contents, buffers are either empty, contain
+ * characters (before shaping) or glyphs (the result of shaping).
  *
  * Since: 0.9.5
  **/
@@ -859,11 +897,12 @@ hb_buffer_set_content_type (hb_buffer_t              *buffer,
 
 /**
  * hb_buffer_get_content_type:
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  *
- * 
+ * see hb_buffer_set_content_type().
  *
- * Return value: 
+ * Return value:
+ * The type of @buffer contents.
  *
  * Since: 0.9.5
  **/
@@ -876,7 +915,7 @@ hb_buffer_get_content_type (hb_buffer_t *buffer)
 
 /**
  * hb_buffer_set_unicode_funcs:
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  * @unicode_funcs: 
  *
  * 
@@ -901,7 +940,7 @@ hb_buffer_set_unicode_funcs (hb_buffer_t        *buffer,
 
 /**
  * hb_buffer_get_unicode_funcs:
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  *
  * 
  *
@@ -917,10 +956,16 @@ hb_buffer_get_unicode_funcs (hb_buffer_t        *buffer)
 
 /**
  * hb_buffer_set_direction:
- * @buffer: a buffer.
- * @direction: 
+ * @buffer: an #hb_buffer_t.
+ * @direction: the #hb_direction_t of the @buffer
  *
- * 
+ * Set the text flow direction of the buffer. No shaping can happen without
+ * setting @buffer direction, and it controls the visual direction for the
+ * output glyphs; for RTL direction the glyphs will be reversed. Many layout
+ * features depend on the proper setting of the direction, for example,
+ * reversing RTL text before shaping, then shaping with LTR direction is not
+ * the same as keeping the text in logical order and shaping with RTL
+ * direction.
  *
  * Since: 0.9.2
  **/
@@ -937,11 +982,12 @@ hb_buffer_set_direction (hb_buffer_t    *buffer,
 
 /**
  * hb_buffer_get_direction:
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  *
- * 
+ * See hb_buffer_set_direction()
  *
- * Return value: 
+ * Return value:
+ * The direction of the @buffer.
  *
  * Since: 0.9.2
  **/
@@ -953,10 +999,18 @@ hb_buffer_get_direction (hb_buffer_t    *buffer)
 
 /**
  * hb_buffer_set_script:
- * @buffer: a buffer.
- * @script: 
+ * @buffer: an #hb_buffer_t.
+ * @script: an #hb_script_t to set.
  *
- * 
+ * Sets the script of @buffer to @script.
+ *
+ * Script is crucial for choosing the proper shaping behaviour for scripts that
+ * require it (e.g. Arabic) and the which OpenType features defined in the font
+ * to be applied.
+ *
+ * You can pass one of the predefined #hb_script_t values, or use
+ * hb_script_from_string() or hb_script_from_iso15924_tag() to get the
+ * corresponding script from an ISO 15924 script tag.
  *
  * Since: 0.9.2
  **/
@@ -972,11 +1026,12 @@ hb_buffer_set_script (hb_buffer_t *buffer,
 
 /**
  * hb_buffer_get_script:
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  *
- * 
+ * See hb_buffer_set_script().
  *
- * Return value: 
+ * Return value:
+ * The #hb_script_t of the @buffer.
  *
  * Since: 0.9.2
  **/
@@ -988,10 +1043,18 @@ hb_buffer_get_script (hb_buffer_t *buffer)
 
 /**
  * hb_buffer_set_language:
- * @buffer: a buffer.
- * @language: 
+ * @buffer: an #hb_buffer_t.
+ * @language: an hb_language_t to set.
  *
- * 
+ * Sets the language of @buffer to @language.
+ *
+ * Languages are crucial for selecting which OpenType feature to apply to the
+ * buffer which can result in applying language-specific behaviour. Languages
+ * are orthogonal to the scripts, and though they are related, they are
+ * different concepts and should not be confused with each other.
+ *
+ * Use hb_language_from_string() to convert from ISO 639 language codes to
+ * #hb_language_t.
  *
  * Since: 0.9.2
  **/
@@ -1007,11 +1070,12 @@ hb_buffer_set_language (hb_buffer_t   *buffer,
 
 /**
  * hb_buffer_get_language:
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  *
- * 
+ * See hb_buffer_set_language().
  *
  * Return value: (transfer none):
+ * The #hb_language_t of the buffer. Must not be freed by the caller.
  *
  * Since: 0.9.2
  **/
@@ -1023,10 +1087,12 @@ hb_buffer_get_language (hb_buffer_t *buffer)
 
 /**
  * hb_buffer_set_segment_properties:
- * @buffer: a buffer.
- * @props: 
+ * @buffer: an #hb_buffer_t.
+ * @props: an #hb_segment_properties_t to use.
  *
- * 
+ * Sets the segment properties of the buffer, a shortcut for calling
+ * hb_buffer_set_direction(), hb_buffer_set_script() and
+ * hb_buffer_set_language() individually.
  *
  * Since: 0.9.7
  **/
@@ -1042,10 +1108,10 @@ hb_buffer_set_segment_properties (hb_buffer_t *buffer,
 
 /**
  * hb_buffer_get_segment_properties:
- * @buffer: a buffer.
- * @props: (out):
+ * @buffer: an #hb_buffer_t.
+ * @props: (out): the output #hb_segment_properties_t.
  *
- * 
+ * Sets @props to the #hb_segment_properties_t of @buffer.
  *
  * Since: 0.9.7
  **/
@@ -1059,10 +1125,10 @@ hb_buffer_get_segment_properties (hb_buffer_t *buffer,
 
 /**
  * hb_buffer_set_flags:
- * @buffer: a buffer.
- * @flags: 
+ * @buffer: an #hb_buffer_t.
+ * @flags: the buffer flags to set.
  *
- * 
+ * Sets @buffer flags to @flags. See #hb_buffer_flags_t.
  *
  * Since: 0.9.7
  **/
@@ -1078,11 +1144,12 @@ hb_buffer_set_flags (hb_buffer_t       *buffer,
 
 /**
  * hb_buffer_get_flags:
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  *
- * 
+ * See hb_buffer_set_flags().
  *
  * Return value: 
+ * The @buffer flags.
  *
  * Since: 0.9.7
  **/
@@ -1094,7 +1161,7 @@ hb_buffer_get_flags (hb_buffer_t *buffer)
 
 /**
  * hb_buffer_set_cluster_level:
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  * @cluster_level: 
  *
  * 
@@ -1113,7 +1180,7 @@ hb_buffer_set_cluster_level (hb_buffer_t       *buffer,
 
 /**
  * hb_buffer_get_cluster_level:
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  *
  * 
  *
@@ -1130,10 +1197,13 @@ hb_buffer_get_cluster_level (hb_buffer_t *buffer)
 
 /**
  * hb_buffer_set_replacement_codepoint:
- * @buffer: a buffer.
- * @replacement: 
+ * @buffer: an #hb_buffer_t.
+ * @replacement: the replacement #hb_codepoint_t
  *
- * 
+ * Sets the #hb_codepoint_t that replaces invalid entries for a given encoding
+ * when adding text to @buffer.
+ *
+ * Default is %HB_BUFFER_REPLACEMENT_CODEPOINT_DEFAULT.
  *
  * Since: 0.9.31
  **/
@@ -1149,11 +1219,12 @@ hb_buffer_set_replacement_codepoint (hb_buffer_t    *buffer,
 
 /**
  * hb_buffer_get_replacement_codepoint:
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  *
- * 
+ * See hb_buffer_set_replacement_codepoint().
  *
  * Return value: 
+ * The @buffer replacement #hb_codepoint_t.
  *
  * Since: 0.9.31
  **/
@@ -1166,9 +1237,10 @@ hb_buffer_get_replacement_codepoint (hb_buffer_t    *buffer)
 
 /**
  * hb_buffer_reset:
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  *
- * 
+ * Resets the buffer to its initial status, as if it was just newly created
+ * with hb_buffer_create().
  *
  * Since: 0.9.2
  **/
@@ -1180,9 +1252,10 @@ hb_buffer_reset (hb_buffer_t *buffer)
 
 /**
  * hb_buffer_clear_contents:
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  *
- * 
+ * Similar to hb_buffer_reset(), but does not clear the Unicode functions and
+ * the replacement code point.
  *
  * Since: 0.9.11
  **/
@@ -1194,12 +1267,13 @@ hb_buffer_clear_contents (hb_buffer_t *buffer)
 
 /**
  * hb_buffer_pre_allocate:
- * @buffer: a buffer.
- * @size: 
+ * @buffer: an #hb_buffer_t.
+ * @size: number of items to pre allocate.
  *
- * 
+ * Pre allocates memory for @buffer to fit at least @size number of items.
  *
- * Return value: 
+ * Return value:
+ * %true if @buffer memory allocation succeeded, %false otherwise.
  *
  * Since: 0.9.2
  **/
@@ -1211,11 +1285,12 @@ hb_buffer_pre_allocate (hb_buffer_t *buffer, unsigned int size)
 
 /**
  * hb_buffer_allocation_successful:
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  *
- * 
+ * Check if allocating memory for the buffer succeeded.
  *
- * Return value: 
+ * Return value:
+ * %true if @buffer memory allocation succeeded, %false otherwise.
  *
  * Since: 0.9.2
  **/
@@ -1227,11 +1302,18 @@ hb_buffer_allocation_successful (hb_buffer_t  *buffer)
 
 /**
  * hb_buffer_add:
- * @buffer: a buffer.
- * @codepoint: 
- * @cluster: 
+ * @buffer: an #hb_buffer_t.
+ * @codepoint: a Unicode code point.
+ * @cluster: the cluster value of @codepoint.
  *
- * 
+ * Appends a character with the Unicode value of @codepoint to @buffer, and
+ * gives it the initial cluster value of @cluster. Clusters can be any thing
+ * the client wants, they are usually used to refer to the index of the
+ * character in the input text stream and are output in
+ * #hb_glyph_info_t.cluster field.
+ *
+ * This function does not check the validity of @codepoint, it is up to the
+ * caller to ensure it is a valid Unicode code point.
  *
  * Since: 0.9.7
  **/
@@ -1246,12 +1328,14 @@ hb_buffer_add (hb_buffer_t    *buffer,
 
 /**
  * hb_buffer_set_length:
- * @buffer: a buffer.
- * @length: 
+ * @buffer: an #hb_buffer_t.
+ * @length: the new length of @buffer.
  *
- * 
+ * Similar to hb_buffer_pre_allocate(), but clears any new items added at the
+ * end.
  *
  * Return value: 
+ * %true if @buffer memory allocation succeeded, %false otherwise.
  *
  * Since: 0.9.2
  **/
@@ -1286,11 +1370,13 @@ hb_buffer_set_length (hb_buffer_t  *buffer,
 
 /**
  * hb_buffer_get_length:
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  *
  * Returns the number of items in the buffer.
  *
- * Return value: buffer length.
+ * Return value:
+ * The @buffer length.
+ * The value valid as long as buffer has not been modified.
  *
  * Since: 0.9.2
  **/
@@ -1302,13 +1388,15 @@ hb_buffer_get_length (hb_buffer_t *buffer)
 
 /**
  * hb_buffer_get_glyph_infos:
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  * @length: (out): output array length.
  *
- * Returns buffer glyph information array.  Returned pointer
- * is valid as long as buffer contents are not modified.
+ * Returns @buffer glyph information array.  Returned pointer
+ * is valid as long as @buffer contents are not modified.
  *
- * Return value: (transfer none) (array length=length): buffer glyph information array.
+ * Return value: (transfer none) (array length=length):
+ * The @buffer glyph information array.
+ * The value valid as long as buffer has not been modified.
  *
  * Since: 0.9.2
  **/
@@ -1324,13 +1412,15 @@ hb_buffer_get_glyph_infos (hb_buffer_t  *buffer,
 
 /**
  * hb_buffer_get_glyph_positions:
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  * @length: (out): output length.
  *
- * Returns buffer glyph position array.  Returned pointer
- * is valid as long as buffer contents are not modified.
+ * Returns @buffer glyph position array.  Returned pointer
+ * is valid as long as @buffer contents are not modified.
  *
- * Return value: (transfer none) (array length=length): buffer glyph position array.
+ * Return value: (transfer none) (array length=length):
+ * The @buffer glyph position array.
+ * The value valid as long as buffer has not been modified.
  *
  * Since: 0.9.2
  **/
@@ -1349,7 +1439,7 @@ hb_buffer_get_glyph_positions (hb_buffer_t  *buffer,
 
 /**
  * hb_buffer_reverse:
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  *
  * Reverses buffer contents.
  *
@@ -1363,7 +1453,7 @@ hb_buffer_reverse (hb_buffer_t *buffer)
 
 /**
  * hb_buffer_reverse_range:
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  * @start: start index.
  * @end: end index.
  *
@@ -1380,7 +1470,7 @@ hb_buffer_reverse_range (hb_buffer_t *buffer,
 
 /**
  * hb_buffer_reverse_clusters:
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  *
  * Reverses buffer clusters.  That is, the buffer contents are
  * reversed, then each cluster (consecutive items having the
@@ -1396,7 +1486,7 @@ hb_buffer_reverse_clusters (hb_buffer_t *buffer)
 
 /**
  * hb_buffer_guess_segment_properties:
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  *
  * Sets unset buffer segment properties based on buffer Unicode
  * contents.  If buffer is not empty, it must have content type
@@ -1495,13 +1585,18 @@ hb_buffer_add_utf (hb_buffer_t  *buffer,
 
 /**
  * hb_buffer_add_utf8:
- * @buffer: a buffer.
- * @text: (array length=text_length) (element-type uint8_t):
- * @text_length: 
- * @item_offset: 
- * @item_length: 
+ * @buffer: an #hb_buffer_t.
+ * @text: (array length=text_length) (element-type uint8_t): an array of UTF-8
+ *               characters to append.
+ * @text_length: the length of the @text, or -1 if it is %NULL terminated.
+ * @item_offset: the offset of the first character to add to the @buffer.
+ * @item_length: the number of characters to add to the @buffer, or -1 for the
+ *               end of @text (assuming it is %NULL terminated).
  *
- * 
+ * See hb_buffer_add_codepoints().
+ *
+ * Replaces invalid UTF-8 characters with the @buffer replacement code point,
+ * see hb_buffer_set_replacement_codepoint().
  *
  * Since: 0.9.2
  **/
@@ -1517,13 +1612,17 @@ hb_buffer_add_utf8 (hb_buffer_t  *buffer,
 
 /**
  * hb_buffer_add_utf16:
- * @buffer: a buffer.
- * @text: (array length=text_length):
- * @text_length: 
- * @item_offset: 
- * @item_length: 
+ * @buffer: an #hb_buffer_t.
+ * @text: (array length=text_length): an array of UTF-16 characters to append.
+ * @text_length: the length of the @text, or -1 if it is %NULL terminated.
+ * @item_offset: the offset of the first character to add to the @buffer.
+ * @item_length: the number of characters to add to the @buffer, or -1 for the
+ *               end of @text (assuming it is %NULL terminated).
  *
- * 
+ * See hb_buffer_add_codepoints().
+ *
+ * Replaces invalid UTF-16 characters with the @buffer replacement code point,
+ * see hb_buffer_set_replacement_codepoint().
  *
  * Since: 0.9.2
  **/
@@ -1539,13 +1638,17 @@ hb_buffer_add_utf16 (hb_buffer_t    *buffer,
 
 /**
  * hb_buffer_add_utf32:
- * @buffer: a buffer.
- * @text: (array length=text_length):
- * @text_length: 
- * @item_offset: 
- * @item_length: 
+ * @buffer: an #hb_buffer_t.
+ * @text: (array length=text_length): an array of UTF-32 characters to append.
+ * @text_length: the length of the @text, or -1 if it is %NULL terminated.
+ * @item_offset: the offset of the first character to add to the @buffer.
+ * @item_length: the number of characters to add to the @buffer, or -1 for the
+ *               end of @text (assuming it is %NULL terminated).
  *
- * 
+ * See hb_buffer_add_codepoints().
+ *
+ * Replaces invalid UTF-32 characters with the @buffer replacement code point,
+ * see hb_buffer_set_replacement_codepoint().
  *
  * Since: 0.9.2
  **/
@@ -1561,13 +1664,18 @@ hb_buffer_add_utf32 (hb_buffer_t    *buffer,
 
 /**
  * hb_buffer_add_latin1:
- * @buffer: a buffer.
- * @text: (array length=text_length) (element-type uint8_t):
- * @text_length: 
- * @item_offset: 
- * @item_length: 
+ * @buffer: an #hb_buffer_t.
+ * @text: (array length=text_length) (element-type uint8_t): an array of UTF-8
+ *               characters to append.
+ * @text_length: the length of the @text, or -1 if it is %NULL terminated.
+ * @item_offset: the offset of the first character to add to the @buffer.
+ * @item_length: the number of characters to add to the @buffer, or -1 for the
+ *               end of @text (assuming it is %NULL terminated).
  *
- * 
+ * Similar to hb_buffer_add_codepoints(), but allows only access to first 256
+ * Unicode code points that can fit in 8-bit strings.
+ *
+ * <note>Has nothing to do with non-Unicode Latin-1 encoding.</note>
  *
  * Since: 0.9.39
  **/
@@ -1583,13 +1691,25 @@ hb_buffer_add_latin1 (hb_buffer_t   *buffer,
 
 /**
  * hb_buffer_add_codepoints:
- * @buffer: a buffer.
- * @text: (array length=text_length):
- * @text_length: 
- * @item_offset: 
- * @item_length: 
- *
- * 
+ * @buffer: a #hb_buffer_t to append characters to.
+ * @text: (array length=text_length): an array of Unicode code points to append.
+ * @text_length: the length of the @text, or -1 if it is %NULL terminated.
+ * @item_offset: the offset of the first code point to add to the @buffer.
+ * @item_length: the number of code points to add to the @buffer, or -1 for the
+ *               end of @text (assuming it is %NULL terminated).
+ *
+ * Appends characters from @text array to @buffer. The @item_offset is the
+ * position of the first character from @text that will be appended, and
+ * @item_length is the number of character. When shaping part of a larger text
+ * (e.g. a run of text from a paragraph), instead of passing just the substring
+ * corresponding to the run, it is preferable to pass the whole
+ * paragraph and specify the run start and length as @item_offset and
+ * @item_length, respectively, to give HarfBuzz the full context to be able,
+ * for example, to do cross-run Arabic shaping or properly handle combining
+ * marks at stat of run.
+ *
+ * This function does not check the validity of @text, it is up to the caller
+ * to ensure it contains a valid Unicode code points.
  *
  * Since: 0.9.31
  **/
@@ -1661,9 +1781,12 @@ normalize_glyphs_cluster (hb_buffer_t *buffer,
 
 /**
  * hb_buffer_normalize_glyphs:
- * @buffer: a buffer.
+ * @buffer: an #hb_buffer_t.
  *
- * 
+ * Reorders a glyph buffer to have canonical in-cluster glyph order / position.
+ * The resulting clusters should behave identical to pre-reordering clusters.
+ *
+ * <note>This has nothing to do with Unicode normalization.</note>
  *
  * Since: 0.9.2
  **/
@@ -1709,3 +1832,45 @@ hb_buffer_t::sort (unsigned int start, unsigned int end, int(*compar)(const hb_g
     }
   }
 }
+
+/*
+ * Debugging.
+ */
+
+/**
+ * hb_buffer_set_message_func:
+ * @buffer: an #hb_buffer_t.
+ * @func: (closure user_data) (destroy destroy) (scope notified):
+ * @user_data:
+ * @destroy:
+ *
+ * 
+ *
+ * Since: 1.1.3
+ **/
+void
+hb_buffer_set_message_func (hb_buffer_t *buffer,
+			    hb_buffer_message_func_t func,
+			    void *user_data, hb_destroy_func_t destroy)
+{
+  if (buffer->message_destroy)
+    buffer->message_destroy (buffer->message_data);
+
+  if (func) {
+    buffer->message_func = func;
+    buffer->message_data = user_data;
+    buffer->message_destroy = destroy;
+  } else {
+    buffer->message_func = NULL;
+    buffer->message_data = NULL;
+    buffer->message_destroy = NULL;
+  }
+}
+
+bool
+hb_buffer_t::message_impl (hb_font_t *font, const char *fmt, va_list ap)
+{
+  char buf[100];
+  vsnprintf (buf, sizeof (buf),  fmt, ap);
+  return (bool) this->message_func (this, font, buf, this->message_data);
+}