util/shape-options.hh - third_party/harfbuzz - Git at Google

 /*
  * Copyright © 2011  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.
  *
  * Google Author(s): Behdad Esfahbod
  */

 #ifndef SHAPE_OPTIONS_HH
 #define SHAPE_OPTIONS_HH

 #include "options.hh"

 struct shape_options_t
 {
   ~shape_options_t ()
   {
     g_free (direction);
     g_free (language);
     g_free (script);
     free (features);
     g_strfreev (shapers);
   }

   void add_options (option_parser_t *parser);

   void setup_buffer (hb_buffer_t *buffer)
   {
     hb_buffer_set_direction (buffer, hb_direction_from_string (direction, -1));
     hb_buffer_set_script (buffer, hb_script_from_string (script, -1));
     hb_buffer_set_language (buffer, hb_language_from_string (language, -1));
     hb_buffer_set_flags (buffer, (hb_buffer_flags_t)
 				 (HB_BUFFER_FLAG_DEFAULT |
 				  (bot ? HB_BUFFER_FLAG_BOT : 0) |
 				  (eot ? HB_BUFFER_FLAG_EOT : 0) |
 				  (preserve_default_ignorables ? HB_BUFFER_FLAG_PRESERVE_DEFAULT_IGNORABLES : 0) |
 				  (remove_default_ignorables ? HB_BUFFER_FLAG_REMOVE_DEFAULT_IGNORABLES : 0) |
 				  0));
     hb_buffer_set_invisible_glyph (buffer, invisible_glyph);
     hb_buffer_set_cluster_level (buffer, cluster_level);
     hb_buffer_guess_segment_properties (buffer);
   }

   static void copy_buffer_properties (hb_buffer_t *dst, hb_buffer_t *src)
   {
     hb_segment_properties_t props;
     hb_buffer_get_segment_properties (src, &props);
     hb_buffer_set_segment_properties (dst, &props);
     hb_buffer_set_flags (dst, hb_buffer_get_flags (src));
     hb_buffer_set_cluster_level (dst, hb_buffer_get_cluster_level (src));
   }

   void populate_buffer (hb_buffer_t *buffer, const char *text, int text_len,
 			const char *text_before, const char *text_after)
   {
     hb_buffer_clear_contents (buffer);
     if (text_before) {
       unsigned int len = strlen (text_before);
       hb_buffer_add_utf8 (buffer, text_before, len, len, 0);
     }
     hb_buffer_add_utf8 (buffer, text, text_len, 0, text_len);
     if (text_after) {
       hb_buffer_add_utf8 (buffer, text_after, -1, 0, 0);
     }

     if (!utf8_clusters) {
       /* Reset cluster values to refer to Unicode character index
        * instead of UTF-8 index. */
       unsigned int num_glyphs = hb_buffer_get_length (buffer);
       hb_glyph_info_t *info = hb_buffer_get_glyph_infos (buffer, nullptr);
       for (unsigned int i = 0; i < num_glyphs; i++)
       {
 	info->cluster = i;
 	info++;
       }
     }

     setup_buffer (buffer);
   }

   hb_bool_t shape (hb_font_t *font, hb_buffer_t *buffer, const char **error=nullptr)
   {
     hb_buffer_t *text_buffer = nullptr;
     if (verify)
     {
       text_buffer = hb_buffer_create ();
       hb_buffer_append (text_buffer, buffer, 0, -1);
     }

     if (!hb_shape_full (font, buffer, features, num_features, shapers))
     {
       if (error)
 	*error = "All shapers failed.";
       goto fail;
     }

     if (normalize_glyphs)
       hb_buffer_normalize_glyphs (buffer);

     if (verify && !verify_buffer (buffer, text_buffer, font, error))
       goto fail;

     if (text_buffer)
       hb_buffer_destroy (text_buffer);

     return true;

   fail:
     if (text_buffer)
       hb_buffer_destroy (text_buffer);

     return false;
   }

   bool verify_buffer (hb_buffer_t  *buffer,
 		      hb_buffer_t  *text_buffer,
 		      hb_font_t    *font,
 		      const char  **error=nullptr)
   {
     if (!verify_buffer_monotone (buffer, error))
       return false;
     if (!verify_buffer_safe_to_break (buffer, text_buffer, font, error))
       return false;
     return true;
   }

   bool verify_buffer_monotone (hb_buffer_t *buffer, const char **error=nullptr)
   {
     /* Check that clusters are monotone. */
     if (cluster_level == HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES ||
 	cluster_level == HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS)
     {
       bool is_forward = HB_DIRECTION_IS_FORWARD (hb_buffer_get_direction (buffer));

       unsigned int num_glyphs;
       hb_glyph_info_t *info = hb_buffer_get_glyph_infos (buffer, &num_glyphs);

       for (unsigned int i = 1; i < num_glyphs; i++)
 	if (info[i-1].cluster != info[i].cluster &&
 	    (info[i-1].cluster < info[i].cluster) != is_forward)
 	{
 	  if (error)
 	    *error = "clusters are not monotone.";
 	  return false;
 	}
     }

     return true;
   }

   bool verify_buffer_safe_to_break (hb_buffer_t  *buffer,
 				    hb_buffer_t  *text_buffer,
 				    hb_font_t    *font,
 				    const char  **error=nullptr)
   {
     if (cluster_level != HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES &&
 	cluster_level != HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS)
     {
       /* Cannot perform this check without monotone clusters.
        * Then again, unsafe-to-break flag is much harder to use without
        * monotone clusters. */
       return true;
     }

     /* Check that breaking up shaping at safe-to-break is indeed safe. */

     hb_buffer_t *fragment = hb_buffer_create ();
     hb_buffer_t *reconstruction = hb_buffer_create ();
     copy_buffer_properties (reconstruction, buffer);

     unsigned int num_glyphs;
     hb_glyph_info_t *info = hb_buffer_get_glyph_infos (buffer, &num_glyphs);

     unsigned int num_chars;
     hb_glyph_info_t *text = hb_buffer_get_glyph_infos (text_buffer, &num_chars);

     /* Chop text and shape fragments. */
     bool forward = HB_DIRECTION_IS_FORWARD (hb_buffer_get_direction (buffer));
     unsigned int start = 0;
     unsigned int text_start = forward ? 0 : num_chars;
     unsigned int text_end = text_start;
     for (unsigned int end = 1; end < num_glyphs + 1; end++)
     {
       if (end < num_glyphs &&
 	  (info[end].cluster == info[end-1].cluster ||
 	   info[end-(forward?0:1)].mask & HB_GLYPH_FLAG_UNSAFE_TO_BREAK))
 	  continue;

       /* Shape segment corresponding to glyphs start..end. */
       if (end == num_glyphs)
       {
 	if (forward)
 	  text_end = num_chars;
 	else
 	  text_start = 0;
       }
       else
       {
 	if (forward)
 	{
 	  unsigned int cluster = info[end].cluster;
 	  while (text_end < num_chars && text[text_end].cluster < cluster)
 	    text_end++;
 	}
 	else
 	{
 	  unsigned int cluster = info[end - 1].cluster;
 	  while (text_start && text[text_start - 1].cluster >= cluster)
 	    text_start--;
 	}
       }
       assert (text_start < text_end);

       if (0)
 	printf("start %d end %d text start %d end %d\n", start, end, text_start, text_end);

       hb_buffer_clear_contents (fragment);
       copy_buffer_properties (fragment, buffer);

       hb_buffer_flags_t flags = hb_buffer_get_flags (fragment);
       if (0 < text_start)
 	flags = (hb_buffer_flags_t) (flags & ~HB_BUFFER_FLAG_BOT);
       if (text_end < num_chars)
 	flags = (hb_buffer_flags_t) (flags & ~HB_BUFFER_FLAG_EOT);
       hb_buffer_set_flags (fragment, flags);

       hb_buffer_append (fragment, text_buffer, text_start, text_end);
       if (!hb_shape_full (font, fragment, features, num_features, shapers))
       {
 	if (error)
 	  *error = "All shapers failed while shaping fragment.";
 	hb_buffer_destroy (reconstruction);
 	hb_buffer_destroy (fragment);
 	return false;
       }
       hb_buffer_append (reconstruction, fragment, 0, -1);

       start = end;
       if (forward)
 	text_start = text_end;
       else
 	text_end = text_start;
     }

     bool ret = true;
     hb_buffer_diff_flags_t diff = hb_buffer_diff (reconstruction, buffer, (hb_codepoint_t) -1, 0);
     if (diff)
     {
       if (error)
 	*error = "Safe-to-break test failed.";
       ret = false;

       /* Return the reconstructed result instead so it can be inspected. */
       hb_buffer_set_length (buffer, 0);
       hb_buffer_append (buffer, reconstruction, 0, -1);
     }

     hb_buffer_destroy (reconstruction);
     hb_buffer_destroy (fragment);

     return ret;
   }

   void shape_closure (const char *text, int text_len,
 		      hb_font_t *font, hb_buffer_t *buffer,
 		      hb_set_t *glyphs)
   {
     hb_buffer_reset (buffer);
     hb_buffer_add_utf8 (buffer, text, text_len, 0, text_len);
     setup_buffer (buffer);
     hb_ot_shape_glyphs_closure (font, buffer, features, num_features, glyphs);
   }

   /* Buffer properties */
   char *direction = nullptr;
   char *language = nullptr;
   char *script = nullptr;

   /* Buffer flags */
   hb_bool_t bot = false;
   hb_bool_t eot = false;
   hb_bool_t preserve_default_ignorables = false;
   hb_bool_t remove_default_ignorables = false;

   hb_feature_t *features = nullptr;
   unsigned int num_features = 0;
   char **shapers = nullptr;
   hb_bool_t utf8_clusters = false;
   hb_codepoint_t invisible_glyph = 0;
   hb_buffer_cluster_level_t cluster_level = HB_BUFFER_CLUSTER_LEVEL_DEFAULT;
   hb_bool_t normalize_glyphs = false;
   hb_bool_t verify = false;
   unsigned int num_iterations = 1;
 };


 static gboolean
 parse_shapers (const char *name G_GNUC_UNUSED,
 	       const char *arg,
 	       gpointer    data,
 	       GError    **error)
 {
   shape_options_t *shape_opts = (shape_options_t *) data;
   char **shapers = g_strsplit (arg, ",", 0);

   for (char **shaper = shapers; *shaper; shaper++)
   {
     bool found = false;
     for (const char **hb_shaper = hb_shape_list_shapers (); *hb_shaper; hb_shaper++) {
       if (strcmp (*shaper, *hb_shaper) == 0)
       {
 	found = true;
 	break;
       }
     }
     if (!found)
     {
       g_set_error (error, G_OPTION_ERROR, G_OPTION_ERROR_BAD_VALUE,
 		   "Unknown or unsupported shaper: %s", *shaper);
       g_strfreev (shapers);
       return false;
     }
   }

   g_strfreev (shape_opts->shapers);
   shape_opts->shapers = shapers;
   return true;
 }

 static G_GNUC_NORETURN gboolean
 list_shapers (const char *name G_GNUC_UNUSED,
 	      const char *arg G_GNUC_UNUSED,
 	      gpointer    data G_GNUC_UNUSED,
 	      GError    **error G_GNUC_UNUSED)
 {
   for (const char **shaper = hb_shape_list_shapers (); *shaper; shaper++)
     g_printf ("%s\n", *shaper);

   exit(0);
 }


 static gboolean
 parse_features (const char *name G_GNUC_UNUSED,
 		const char *arg,
 		gpointer    data,
 		GError    **error G_GNUC_UNUSED)
 {
   shape_options_t *shape_opts = (shape_options_t *) data;
   char *s = (char *) arg;
   size_t l = strlen (s);
   char *p;

   shape_opts->num_features = 0;
   g_free (shape_opts->features);
   shape_opts->features = nullptr;

   /* if the string is quoted, strip the quotes */
   if (s[0] == s[l - 1] && (s[0] == '\"' || s[0] == '\''))
   {
     s[l - 1] = '\0';
     s++;
   }

   if (!*s)
     return true;

   /* count the features first, so we can allocate memory */
   p = s;
   do {
     shape_opts->num_features++;
     p = strchr (p, ',');
     if (p)
       p++;
   } while (p);

   shape_opts->features = (hb_feature_t *) calloc (shape_opts->num_features, sizeof (*shape_opts->features));
   if (!shape_opts->features)
     return false;

   /* now do the actual parsing */
   p = s;
   shape_opts->num_features = 0;
   while (p && *p) {
     char *end = strchr (p, ',');
     if (hb_feature_from_string (p, end ? end - p : -1, &shape_opts->features[shape_opts->num_features]))
       shape_opts->num_features++;
     p = end ? end + 1 : nullptr;
   }

   return true;
 }

 void
 shape_options_t::add_options (option_parser_t *parser)
 {
   GOptionEntry entries[] =
   {
     {"list-shapers",	0, G_OPTION_FLAG_NO_ARG,
 			      G_OPTION_ARG_CALLBACK,	(gpointer) &list_shapers,	"List available shapers and quit",	nullptr},
     {"shaper",		0, G_OPTION_FLAG_HIDDEN,
 			      G_OPTION_ARG_CALLBACK,	(gpointer) &parse_shapers,	"Hidden duplicate of --shapers",	nullptr},
     {"shapers",		0, 0, G_OPTION_ARG_CALLBACK,	(gpointer) &parse_shapers,	"Set comma-separated list of shapers to try","list"},
     {"direction",	0, 0, G_OPTION_ARG_STRING,	&this->direction,		"Set text direction (default: auto)",	"ltr/rtl/ttb/btt"},
     {"language",	0, 0, G_OPTION_ARG_STRING,	&this->language,		"Set text language (default: $LANG)",	"BCP 47 tag"},
     {"script",		0, 0, G_OPTION_ARG_STRING,	&this->script,			"Set text script (default: auto)",	"ISO-15924 tag"},
     {"bot",		0, 0, G_OPTION_ARG_NONE,	&this->bot,			"Treat text as beginning-of-paragraph",	nullptr},
     {"eot",		0, 0, G_OPTION_ARG_NONE,	&this->eot,			"Treat text as end-of-paragraph",	nullptr},
     {"preserve-default-ignorables",0, 0, G_OPTION_ARG_NONE,	&this->preserve_default_ignorables,	"Preserve Default-Ignorable characters",	nullptr},
     {"remove-default-ignorables",0, 0, G_OPTION_ARG_NONE,	&this->remove_default_ignorables,	"Remove Default-Ignorable characters",	nullptr},
     {"invisible-glyph",	0, 0, G_OPTION_ARG_INT,		&this->invisible_glyph,		"Glyph value to replace Default-Ignorables with",	nullptr},
     {"utf8-clusters",	0, 0, G_OPTION_ARG_NONE,	&this->utf8_clusters,		"Use UTF8 byte indices, not char indices",	nullptr},
     {"cluster-level",	0, 0, G_OPTION_ARG_INT,		&this->cluster_level,		"Cluster merging level (default: 0)",	"0/1/2"},
     {"normalize-glyphs",0, 0, G_OPTION_ARG_NONE,	&this->normalize_glyphs,	"Rearrange glyph clusters in nominal order",	nullptr},
     {"verify",		0, 0, G_OPTION_ARG_NONE,	&this->verify,			"Perform sanity checks on shaping results",	nullptr},
     {"num-iterations", 'n', G_OPTION_FLAG_IN_MAIN,
 			      G_OPTION_ARG_INT,		&this->num_iterations,		"Run shaper N times (default: 1)",	"N"},
     {nullptr}
   };
   parser->add_group (entries,
 		     "shape",
 		     "Shape options:",
 		     "Options for the shaping process",
 		     this);

   const gchar *features_help = "Comma-separated list of font features\n"
     "\n"
     "    Features can be enabled or disabled, either globally or limited to\n"
     "    specific character ranges.  The format for specifying feature settings\n"
     "    follows.  All valid CSS font-feature-settings values other than 'normal'\n"
     "    and the global values are also accepted, though not documented below.\n"
     "    CSS string escapes are not supported."
     "\n"
     "    The range indices refer to the positions between Unicode characters,\n"
     "    unless the --utf8-clusters is provided, in which case range indices\n"
     "    refer to UTF-8 byte indices. The position before the first character\n"
     "    is always 0.\n"
     "\n"
     "    The format is Python-esque.  Here is how it all works:\n"
     "\n"
     "      Syntax:       Value:    Start:    End:\n"
     "\n"
     "    Setting value:\n"
     "      \"kern\"        1         0         ∞         # Turn feature on\n"
     "      \"+kern\"       1         0         ∞         # Turn feature on\n"
     "      \"-kern\"       0         0         ∞         # Turn feature off\n"
     "      \"kern=0\"      0         0         ∞         # Turn feature off\n"
     "      \"kern=1\"      1         0         ∞         # Turn feature on\n"
     "      \"aalt=2\"      2         0         ∞         # Choose 2nd alternate\n"
     "\n"
     "    Setting index:\n"
     "      \"kern[]\"      1         0         ∞         # Turn feature on\n"
     "      \"kern[:]\"     1         0         ∞         # Turn feature on\n"
     "      \"kern[5:]\"    1         5         ∞         # Turn feature on, partial\n"
     "      \"kern[:5]\"    1         0         5         # Turn feature on, partial\n"
     "      \"kern[3:5]\"   1         3         5         # Turn feature on, range\n"
     "      \"kern[3]\"     1         3         3+1       # Turn feature on, single char\n"
     "\n"
     "    Mixing it all:\n"
     "\n"
     "      \"aalt[3:5]=2\" 2         3         5         # Turn 2nd alternate on for range";

   GOptionEntry entries2[] =
   {
     {"features",	0, 0, G_OPTION_ARG_CALLBACK,	(gpointer) &parse_features,	features_help,	"list"},
     {nullptr}
   };
   parser->add_group (entries2,
 		     "features",
 		     "Features options:",
 		     "Options for font features used",
 		     this);
 }

 #endif
	/*
	* Copyright © 2011 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.
	*
	* Google Author(s): Behdad Esfahbod
	*/

	#ifndef SHAPE_OPTIONS_HH
	#define SHAPE_OPTIONS_HH

	#include "options.hh"

	struct shape_options_t
	{
	~shape_options_t ()
	{
	g_free (direction);
	g_free (language);
	g_free (script);
	free (features);
	g_strfreev (shapers);
	}

	void add_options (option_parser_t *parser);

	void setup_buffer (hb_buffer_t *buffer)
	{
	hb_buffer_set_direction (buffer, hb_direction_from_string (direction, -1));
	hb_buffer_set_script (buffer, hb_script_from_string (script, -1));
	hb_buffer_set_language (buffer, hb_language_from_string (language, -1));
	hb_buffer_set_flags (buffer, (hb_buffer_flags_t)
	(HB_BUFFER_FLAG_DEFAULT \|
	(bot ? HB_BUFFER_FLAG_BOT : 0) \|
	(eot ? HB_BUFFER_FLAG_EOT : 0) \|
	(preserve_default_ignorables ? HB_BUFFER_FLAG_PRESERVE_DEFAULT_IGNORABLES : 0) \|
	(remove_default_ignorables ? HB_BUFFER_FLAG_REMOVE_DEFAULT_IGNORABLES : 0) \|
	0));
	hb_buffer_set_invisible_glyph (buffer, invisible_glyph);
	hb_buffer_set_cluster_level (buffer, cluster_level);
	hb_buffer_guess_segment_properties (buffer);
	}

	static void copy_buffer_properties (hb_buffer_t dst, hb_buffer_t src)
	{
	hb_segment_properties_t props;
	hb_buffer_get_segment_properties (src, &props);
	hb_buffer_set_segment_properties (dst, &props);
	hb_buffer_set_flags (dst, hb_buffer_get_flags (src));
	hb_buffer_set_cluster_level (dst, hb_buffer_get_cluster_level (src));
	}

	void populate_buffer (hb_buffer_t buffer, const char text, int text_len,
	const char text_before, const char text_after)
	{
	hb_buffer_clear_contents (buffer);
	if (text_before) {
	unsigned int len = strlen (text_before);
	hb_buffer_add_utf8 (buffer, text_before, len, len, 0);
	}
	hb_buffer_add_utf8 (buffer, text, text_len, 0, text_len);
	if (text_after) {
	hb_buffer_add_utf8 (buffer, text_after, -1, 0, 0);
	}

	if (!utf8_clusters) {
	/* Reset cluster values to refer to Unicode character index
	* instead of UTF-8 index. */
	unsigned int num_glyphs = hb_buffer_get_length (buffer);
	hb_glyph_info_t *info = hb_buffer_get_glyph_infos (buffer, nullptr);
	for (unsigned int i = 0; i < num_glyphs; i++)
	{
	info->cluster = i;
	info++;
	}
	}

	setup_buffer (buffer);
	}

	hb_bool_t shape (hb_font_t font, hb_buffer_t buffer, const char **error=nullptr)
	{
	hb_buffer_t *text_buffer = nullptr;
	if (verify)
	{
	text_buffer = hb_buffer_create ();
	hb_buffer_append (text_buffer, buffer, 0, -1);
	}

	if (!hb_shape_full (font, buffer, features, num_features, shapers))
	{
	if (error)
	*error = "All shapers failed.";
	goto fail;
	}

	if (normalize_glyphs)
	hb_buffer_normalize_glyphs (buffer);

	if (verify && !verify_buffer (buffer, text_buffer, font, error))
	goto fail;

	if (text_buffer)
	hb_buffer_destroy (text_buffer);

	return true;

	fail:
	if (text_buffer)
	hb_buffer_destroy (text_buffer);

	return false;
	}

	bool verify_buffer (hb_buffer_t *buffer,
	hb_buffer_t *text_buffer,
	hb_font_t *font,
	const char **error=nullptr)
	{
	if (!verify_buffer_monotone (buffer, error))
	return false;
	if (!verify_buffer_safe_to_break (buffer, text_buffer, font, error))
	return false;
	return true;
	}

	bool verify_buffer_monotone (hb_buffer_t buffer, const char *error=nullptr)
	{
	/* Check that clusters are monotone. */
	if (cluster_level == HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES \|\|
	cluster_level == HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS)
	{
	bool is_forward = HB_DIRECTION_IS_FORWARD (hb_buffer_get_direction (buffer));

	unsigned int num_glyphs;
	hb_glyph_info_t *info = hb_buffer_get_glyph_infos (buffer, &num_glyphs);

	for (unsigned int i = 1; i < num_glyphs; i++)
	if (info[i-1].cluster != info[i].cluster &&
	(info[i-1].cluster < info[i].cluster) != is_forward)
	{
	if (error)
	*error = "clusters are not monotone.";
	return false;
	}
	}

	return true;
	}

	bool verify_buffer_safe_to_break (hb_buffer_t *buffer,
	hb_buffer_t *text_buffer,
	hb_font_t *font,
	const char **error=nullptr)
	{
	if (cluster_level != HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES &&
	cluster_level != HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS)
	{
	/* Cannot perform this check without monotone clusters.
	* Then again, unsafe-to-break flag is much harder to use without
	* monotone clusters. */
	return true;
	}

	/* Check that breaking up shaping at safe-to-break is indeed safe. */

	hb_buffer_t *fragment = hb_buffer_create ();
	hb_buffer_t *reconstruction = hb_buffer_create ();
	copy_buffer_properties (reconstruction, buffer);

	unsigned int num_glyphs;
	hb_glyph_info_t *info = hb_buffer_get_glyph_infos (buffer, &num_glyphs);

	unsigned int num_chars;
	hb_glyph_info_t *text = hb_buffer_get_glyph_infos (text_buffer, &num_chars);

	/* Chop text and shape fragments. */
	bool forward = HB_DIRECTION_IS_FORWARD (hb_buffer_get_direction (buffer));
	unsigned int start = 0;
	unsigned int text_start = forward ? 0 : num_chars;
	unsigned int text_end = text_start;
	for (unsigned int end = 1; end < num_glyphs + 1; end++)
	{
	if (end < num_glyphs &&
	(info[end].cluster == info[end-1].cluster \|\|
	info[end-(forward?0:1)].mask & HB_GLYPH_FLAG_UNSAFE_TO_BREAK))
	continue;

	/* Shape segment corresponding to glyphs start..end. */
	if (end == num_glyphs)
	{
	if (forward)
	text_end = num_chars;
	else
	text_start = 0;
	}
	else
	{
	if (forward)
	{
	unsigned int cluster = info[end].cluster;
	while (text_end < num_chars && text[text_end].cluster < cluster)
	text_end++;
	}
	else
	{
	unsigned int cluster = info[end - 1].cluster;
	while (text_start && text[text_start - 1].cluster >= cluster)
	text_start--;
	}
	}
	assert (text_start < text_end);

	if (0)
	printf("start %d end %d text start %d end %d\n", start, end, text_start, text_end);

	hb_buffer_clear_contents (fragment);
	copy_buffer_properties (fragment, buffer);

	hb_buffer_flags_t flags = hb_buffer_get_flags (fragment);
	if (0 < text_start)
	flags = (hb_buffer_flags_t) (flags & ~HB_BUFFER_FLAG_BOT);
	if (text_end < num_chars)
	flags = (hb_buffer_flags_t) (flags & ~HB_BUFFER_FLAG_EOT);
	hb_buffer_set_flags (fragment, flags);

	hb_buffer_append (fragment, text_buffer, text_start, text_end);
	if (!hb_shape_full (font, fragment, features, num_features, shapers))
	{
	if (error)
	*error = "All shapers failed while shaping fragment.";
	hb_buffer_destroy (reconstruction);
	hb_buffer_destroy (fragment);
	return false;
	}
	hb_buffer_append (reconstruction, fragment, 0, -1);

	start = end;
	if (forward)
	text_start = text_end;
	else
	text_end = text_start;
	}

	bool ret = true;
	hb_buffer_diff_flags_t diff = hb_buffer_diff (reconstruction, buffer, (hb_codepoint_t) -1, 0);
	if (diff)
	{
	if (error)
	*error = "Safe-to-break test failed.";
	ret = false;

	/* Return the reconstructed result instead so it can be inspected. */
	hb_buffer_set_length (buffer, 0);
	hb_buffer_append (buffer, reconstruction, 0, -1);
	}

	hb_buffer_destroy (reconstruction);
	hb_buffer_destroy (fragment);

	return ret;
	}

	void shape_closure (const char *text, int text_len,
	hb_font_t font, hb_buffer_t buffer,
	hb_set_t *glyphs)
	{
	hb_buffer_reset (buffer);
	hb_buffer_add_utf8 (buffer, text, text_len, 0, text_len);
	setup_buffer (buffer);
	hb_ot_shape_glyphs_closure (font, buffer, features, num_features, glyphs);
	}

	/* Buffer properties */
	char *direction = nullptr;
	char *language = nullptr;
	char *script = nullptr;

	/* Buffer flags */
	hb_bool_t bot = false;
	hb_bool_t eot = false;
	hb_bool_t preserve_default_ignorables = false;
	hb_bool_t remove_default_ignorables = false;

	hb_feature_t *features = nullptr;
	unsigned int num_features = 0;
	char **shapers = nullptr;
	hb_bool_t utf8_clusters = false;
	hb_codepoint_t invisible_glyph = 0;
	hb_buffer_cluster_level_t cluster_level = HB_BUFFER_CLUSTER_LEVEL_DEFAULT;
	hb_bool_t normalize_glyphs = false;
	hb_bool_t verify = false;
	unsigned int num_iterations = 1;
	};


	static gboolean
	parse_shapers (const char *name G_GNUC_UNUSED,
	const char *arg,
	gpointer data,
	GError **error)
	{
	shape_options_t shape_opts = (shape_options_t ) data;
	char **shapers = g_strsplit (arg, ",", 0);

	for (char *shaper = shapers; shaper; shaper++)
	{
	bool found = false;
	for (const char *hb_shaper = hb_shape_list_shapers (); hb_shaper; hb_shaper++) {
	if (strcmp (shaper, hb_shaper) == 0)
	{
	found = true;
	break;
	}
	}
	if (!found)
	{
	g_set_error (error, G_OPTION_ERROR, G_OPTION_ERROR_BAD_VALUE,
	"Unknown or unsupported shaper: %s", *shaper);
	g_strfreev (shapers);
	return false;
	}
	}

	g_strfreev (shape_opts->shapers);
	shape_opts->shapers = shapers;
	return true;
	}

	static G_GNUC_NORETURN gboolean
	list_shapers (const char *name G_GNUC_UNUSED,
	const char *arg G_GNUC_UNUSED,
	gpointer data G_GNUC_UNUSED,
	GError **error G_GNUC_UNUSED)
	{
	for (const char *shaper = hb_shape_list_shapers (); shaper; shaper++)
	g_printf ("%s\n", *shaper);

	exit(0);
	}


	static gboolean
	parse_features (const char *name G_GNUC_UNUSED,
	const char *arg,
	gpointer data,
	GError **error G_GNUC_UNUSED)
	{
	shape_options_t shape_opts = (shape_options_t ) data;
	char s = (char ) arg;
	size_t l = strlen (s);
	char *p;

	shape_opts->num_features = 0;
	g_free (shape_opts->features);
	shape_opts->features = nullptr;

	/* if the string is quoted, strip the quotes */
	if (s[0] == s[l - 1] && (s[0] == '\"' \|\| s[0] == '\''))
	{
	s[l - 1] = '\0';
	s++;
	}

	if (!*s)
	return true;

	/* count the features first, so we can allocate memory */
	p = s;
	do {
	shape_opts->num_features++;
	p = strchr (p, ',');
	if (p)
	p++;
	} while (p);

	shape_opts->features = (hb_feature_t ) calloc (shape_opts->num_features, sizeof (shape_opts->features));
	if (!shape_opts->features)
	return false;

	/* now do the actual parsing */
	p = s;
	shape_opts->num_features = 0;
	while (p && *p) {
	char *end = strchr (p, ',');
	if (hb_feature_from_string (p, end ? end - p : -1, &shape_opts->features[shape_opts->num_features]))
	shape_opts->num_features++;
	p = end ? end + 1 : nullptr;
	}

	return true;
	}

	void
	shape_options_t::add_options (option_parser_t *parser)
	{
	GOptionEntry entries[] =
	{
	{"list-shapers", 0, G_OPTION_FLAG_NO_ARG,
	G_OPTION_ARG_CALLBACK, (gpointer) &list_shapers, "List available shapers and quit", nullptr},
	{"shaper", 0, G_OPTION_FLAG_HIDDEN,
	G_OPTION_ARG_CALLBACK, (gpointer) &parse_shapers, "Hidden duplicate of --shapers", nullptr},
	{"shapers", 0, 0, G_OPTION_ARG_CALLBACK, (gpointer) &parse_shapers, "Set comma-separated list of shapers to try","list"},
	{"direction", 0, 0, G_OPTION_ARG_STRING, &this->direction, "Set text direction (default: auto)", "ltr/rtl/ttb/btt"},
	{"language", 0, 0, G_OPTION_ARG_STRING, &this->language, "Set text language (default: $LANG)", "BCP 47 tag"},
	{"script", 0, 0, G_OPTION_ARG_STRING, &this->script, "Set text script (default: auto)", "ISO-15924 tag"},
	{"bot", 0, 0, G_OPTION_ARG_NONE, &this->bot, "Treat text as beginning-of-paragraph", nullptr},
	{"eot", 0, 0, G_OPTION_ARG_NONE, &this->eot, "Treat text as end-of-paragraph", nullptr},
	{"preserve-default-ignorables",0, 0, G_OPTION_ARG_NONE, &this->preserve_default_ignorables, "Preserve Default-Ignorable characters", nullptr},
	{"remove-default-ignorables",0, 0, G_OPTION_ARG_NONE, &this->remove_default_ignorables, "Remove Default-Ignorable characters", nullptr},
	{"invisible-glyph", 0, 0, G_OPTION_ARG_INT, &this->invisible_glyph, "Glyph value to replace Default-Ignorables with", nullptr},
	{"utf8-clusters", 0, 0, G_OPTION_ARG_NONE, &this->utf8_clusters, "Use UTF8 byte indices, not char indices", nullptr},
	{"cluster-level", 0, 0, G_OPTION_ARG_INT, &this->cluster_level, "Cluster merging level (default: 0)", "0/1/2"},
	{"normalize-glyphs",0, 0, G_OPTION_ARG_NONE, &this->normalize_glyphs, "Rearrange glyph clusters in nominal order", nullptr},
	{"verify", 0, 0, G_OPTION_ARG_NONE, &this->verify, "Perform sanity checks on shaping results", nullptr},
	{"num-iterations", 'n', G_OPTION_FLAG_IN_MAIN,
	G_OPTION_ARG_INT, &this->num_iterations, "Run shaper N times (default: 1)", "N"},
	{nullptr}
	};
	parser->add_group (entries,
	"shape",
	"Shape options:",
	"Options for the shaping process",
	this);

	const gchar *features_help = "Comma-separated list of font features\n"
	"\n"
	" Features can be enabled or disabled, either globally or limited to\n"
	" specific character ranges. The format for specifying feature settings\n"
	" follows. All valid CSS font-feature-settings values other than 'normal'\n"
	" and the global values are also accepted, though not documented below.\n"
	" CSS string escapes are not supported."
	"\n"
	" The range indices refer to the positions between Unicode characters,\n"
	" unless the --utf8-clusters is provided, in which case range indices\n"
	" refer to UTF-8 byte indices. The position before the first character\n"
	" is always 0.\n"
	"\n"
	" The format is Python-esque. Here is how it all works:\n"
	"\n"
	" Syntax: Value: Start: End:\n"
	"\n"
	" Setting value:\n"
	" \"kern\" 1 0 ∞ # Turn feature on\n"
	" \"+kern\" 1 0 ∞ # Turn feature on\n"
	" \"-kern\" 0 0 ∞ # Turn feature off\n"
	" \"kern=0\" 0 0 ∞ # Turn feature off\n"
	" \"kern=1\" 1 0 ∞ # Turn feature on\n"
	" \"aalt=2\" 2 0 ∞ # Choose 2nd alternate\n"
	"\n"
	" Setting index:\n"
	" \"kern[]\" 1 0 ∞ # Turn feature on\n"
	" \"kern[:]\" 1 0 ∞ # Turn feature on\n"
	" \"kern[5:]\" 1 5 ∞ # Turn feature on, partial\n"
	" \"kern[:5]\" 1 0 5 # Turn feature on, partial\n"
	" \"kern[3:5]\" 1 3 5 # Turn feature on, range\n"
	" \"kern[3]\" 1 3 3+1 # Turn feature on, single char\n"
	"\n"
	" Mixing it all:\n"
	"\n"
	" \"aalt[3:5]=2\" 2 3 5 # Turn 2nd alternate on for range";

	GOptionEntry entries2[] =
	{
	{"features", 0, 0, G_OPTION_ARG_CALLBACK, (gpointer) &parse_features, features_help, "list"},
	{nullptr}
	};
	parser->add_group (entries2,
	"features",
	"Features options:",
	"Options for font features used",
	this);
	}

	#endif