harfbuzz/src/hb-ot-tag.cc

/*
 * Copyright © 2009  Red Hat, Inc.
 * 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.
 *
 * Red Hat Author(s): Behdad Esfahbod
 * Google Author(s): Behdad Esfahbod, Roozbeh Pournader
 */

#include "hb.hh"


/* hb_script_t */

static hb_tag_t
hb_ot_old_tag_from_script (hb_script_t script)
{
  /* This seems to be accurate as of end of 2012. */

  switch ((hb_tag_t) script)
  {
    case HB_SCRIPT_INVALID:		return HB_OT_TAG_DEFAULT_SCRIPT;

    /* KATAKANA and HIRAGANA both map to 'kana' */
    case HB_SCRIPT_HIRAGANA:		return HB_TAG('k','a','n','a');

    /* Spaces at the end are preserved, unlike ISO 15924 */
    case HB_SCRIPT_LAO:			return HB_TAG('l','a','o',' ');
    case HB_SCRIPT_YI:			return HB_TAG('y','i',' ',' ');
    /* Unicode-5.0 additions */
    case HB_SCRIPT_NKO:			return HB_TAG('n','k','o',' ');
    /* Unicode-5.1 additions */
    case HB_SCRIPT_VAI:			return HB_TAG('v','a','i',' ');
  }

  /* Else, just change first char to lowercase and return */
  return ((hb_tag_t) script) | 0x20000000u;
}

static hb_script_t
hb_ot_old_tag_to_script (hb_tag_t tag)
{
  if (unlikely (tag == HB_OT_TAG_DEFAULT_SCRIPT))
    return HB_SCRIPT_INVALID;

  /* This side of the conversion is fully algorithmic. */

  /* Any spaces at the end of the tag are replaced by repeating the last
   * letter.  Eg 'nko ' -> 'Nkoo' */
  if (unlikely ((tag & 0x0000FF00u) == 0x00002000u))
    tag |= (tag >> 8) & 0x0000FF00u; /* Copy second letter to third */
  if (unlikely ((tag & 0x000000FFu) == 0x00000020u))
    tag |= (tag >> 8) & 0x000000FFu; /* Copy third letter to fourth */

  /* Change first char to uppercase and return */
  return (hb_script_t) (tag & ~0x20000000u);
}

static hb_tag_t
hb_ot_new_tag_from_script (hb_script_t script)
{
  switch ((hb_tag_t) script) {
    case HB_SCRIPT_BENGALI:		return HB_TAG('b','n','g','2');
    case HB_SCRIPT_DEVANAGARI:		return HB_TAG('d','e','v','2');
    case HB_SCRIPT_GUJARATI:		return HB_TAG('g','j','r','2');
    case HB_SCRIPT_GURMUKHI:		return HB_TAG('g','u','r','2');
    case HB_SCRIPT_KANNADA:		return HB_TAG('k','n','d','2');
    case HB_SCRIPT_MALAYALAM:		return HB_TAG('m','l','m','2');
    case HB_SCRIPT_ORIYA:		return HB_TAG('o','r','y','2');
    case HB_SCRIPT_TAMIL:		return HB_TAG('t','m','l','2');
    case HB_SCRIPT_TELUGU:		return HB_TAG('t','e','l','2');
    case HB_SCRIPT_MYANMAR:		return HB_TAG('m','y','m','2');
  }

  return HB_OT_TAG_DEFAULT_SCRIPT;
}

static hb_script_t
hb_ot_new_tag_to_script (hb_tag_t tag)
{
  switch (tag) {
    case HB_TAG('b','n','g','2'):	return HB_SCRIPT_BENGALI;
    case HB_TAG('d','e','v','2'):	return HB_SCRIPT_DEVANAGARI;
    case HB_TAG('g','j','r','2'):	return HB_SCRIPT_GUJARATI;
    case HB_TAG('g','u','r','2'):	return HB_SCRIPT_GURMUKHI;
    case HB_TAG('k','n','d','2'):	return HB_SCRIPT_KANNADA;
    case HB_TAG('m','l','m','2'):	return HB_SCRIPT_MALAYALAM;
    case HB_TAG('o','r','y','2'):	return HB_SCRIPT_ORIYA;
    case HB_TAG('t','m','l','2'):	return HB_SCRIPT_TAMIL;
    case HB_TAG('t','e','l','2'):	return HB_SCRIPT_TELUGU;
    case HB_TAG('m','y','m','2'):	return HB_SCRIPT_MYANMAR;
  }

  return HB_SCRIPT_UNKNOWN;
}

#ifndef HB_DISABLE_DEPRECATED
void
hb_ot_tags_from_script (hb_script_t  script,
			hb_tag_t    *script_tag_1,
			hb_tag_t    *script_tag_2)
{
  unsigned int count = 2;
  hb_tag_t tags[2];
  hb_ot_tags_from_script_and_language (script, HB_LANGUAGE_INVALID, &count, tags, nullptr, nullptr);
  *script_tag_1 = count > 0 ? tags[0] : HB_OT_TAG_DEFAULT_SCRIPT;
  *script_tag_2 = count > 1 ? tags[1] : HB_OT_TAG_DEFAULT_SCRIPT;
}
#endif

/*
 * Complete list at:
 * https://docs.microsoft.com/en-us/typography/opentype/spec/scripttags
 *
 * Most of the script tags are the same as the ISO 15924 tag but lowercased.
 * So we just do that, and handle the exceptional cases in a switch.
 */

static void
hb_ot_all_tags_from_script (hb_script_t   script,
			    unsigned int *count /* IN/OUT */,
			    hb_tag_t     *tags /* OUT */)
{
  unsigned int i = 0;

  hb_tag_t new_tag = hb_ot_new_tag_from_script (script);
  if (unlikely (new_tag != HB_OT_TAG_DEFAULT_SCRIPT))
  {
    /* HB_SCRIPT_MYANMAR maps to 'mym2', but there is no 'mym3'. */
    if (new_tag != HB_TAG('m','y','m','2'))
      tags[i++] = new_tag | '3';
    if (*count > i)
      tags[i++] = new_tag;
  }

  if (*count > i)
  {
    hb_tag_t old_tag = hb_ot_old_tag_from_script (script);
    if (old_tag != HB_OT_TAG_DEFAULT_SCRIPT)
      tags[i++] = old_tag;
  }

  *count = i;
}

hb_script_t
hb_ot_tag_to_script (hb_tag_t tag)
{
  unsigned char digit = tag & 0x000000FFu;
  if (unlikely (digit == '2' || digit == '3'))
    return hb_ot_new_tag_to_script (tag & 0xFFFFFF32);

  return hb_ot_old_tag_to_script (tag);
}


/* hb_language_t */

static bool
subtag_matches (const char *lang_str,
		const char *limit,
		const char *subtag)
{
  do {
    const char *s = strstr (lang_str, subtag);
    if (!s || s >= limit)
      return false;
    if (!ISALNUM (s[strlen (subtag)]))
      return true;
    lang_str = s + strlen (subtag);
  } while (true);
}

static hb_bool_t
lang_matches (const char *lang_str, const char *spec)
{
  unsigned int len = strlen (spec);

  return strncmp (lang_str, spec, len) == 0 &&
	 (lang_str[len] == '\0' || lang_str[len] == '-');
}

struct LangTag
{
  char language[4];
  hb_tag_t tag;

  int cmp (const char *a) const
  {
    const char *b = this->language;
    unsigned int da, db;
    const char *p;

    p = strchr (a, '-');
    da = p ? (unsigned int) (p - a) : strlen (a);

    p = strchr (b, '-');
    db = p ? (unsigned int) (p - b) : strlen (b);

    return strncmp (a, b, hb_max (da, db));
  }
  int cmp (const LangTag *that) const
  { return cmp (that->language); }
};

#include "hb-ot-tag-table.hh"

/* The corresponding languages IDs for the following IDs are unclear,
 * overlap, or are architecturally weird. Needs more research. */

/*{"??",	{HB_TAG('B','C','R',' ')}},*/	/* Bible Cree */
/*{"zh?",	{HB_TAG('C','H','N',' ')}},*/	/* Chinese (seen in Microsoft fonts) */
/*{"ar-Syrc?",	{HB_TAG('G','A','R',' ')}},*/	/* Garshuni */
/*{"??",	{HB_TAG('N','G','R',' ')}},*/	/* Nagari */
/*{"??",	{HB_TAG('Y','I','C',' ')}},*/	/* Yi Classic */
/*{"zh?",	{HB_TAG('Z','H','P',' ')}},*/	/* Chinese Phonetic */

#ifndef HB_DISABLE_DEPRECATED
hb_tag_t
hb_ot_tag_from_language (hb_language_t language)
{
  unsigned int count = 1;
  hb_tag_t tags[1];
  hb_ot_tags_from_script_and_language (HB_SCRIPT_UNKNOWN, language, nullptr, nullptr, &count, tags);
  return count > 0 ? tags[0] : HB_OT_TAG_DEFAULT_LANGUAGE;
}
#endif

static void
hb_ot_tags_from_language (const char   *lang_str,
			  const char   *limit,
			  unsigned int *count,
			  hb_tag_t     *tags)
{
  const char *s;
  unsigned int tag_idx;

  /* Check for matches of multiple subtags. */
  if (hb_ot_tags_from_complex_language (lang_str, limit, count, tags))
    return;

  /* Find a language matching in the first component. */
  s = strchr (lang_str, '-');
  {
    if (s && limit - lang_str >= 6)
    {
      const char *extlang_end = strchr (s + 1, '-');
      /* If there is an extended language tag, use it. */
      if (3 == (extlang_end ? extlang_end - s - 1 : strlen (s + 1)) &&
	  ISALPHA (s[1]))
	lang_str = s + 1;
    }
    if (hb_sorted_array (ot_languages).bfind (lang_str, &tag_idx))
    {
      unsigned int i;
      while (tag_idx != 0 &&
	     0 == strcmp (ot_languages[tag_idx].language, ot_languages[tag_idx - 1].language))
	tag_idx--;
      for (i = 0;
	   i < *count &&
	   tag_idx + i < ARRAY_LENGTH (ot_languages) &&
	   0 == strcmp (ot_languages[tag_idx + i].language, ot_languages[tag_idx].language);
	   i++)
	tags[i] = ot_languages[tag_idx + i].tag;
      *count = i;
      return;
    }
  }

  if (!s)
    s = lang_str + strlen (lang_str);
  if (s - lang_str == 3) {
    /* Assume it's ISO-639-3 and upper-case and use it. */
    tags[0] = hb_tag_from_string (lang_str, s - lang_str) & ~0x20202000u;
    *count = 1;
    return;
  }

  *count = 0;
}

static bool
parse_private_use_subtag (const char     *private_use_subtag,
			  unsigned int   *count,
			  hb_tag_t       *tags,
			  const char     *prefix,
			  unsigned char (*normalize) (unsigned char))
{
  if (!(private_use_subtag && count && tags && *count)) return false;

  const char *s = strstr (private_use_subtag, prefix);
  if (!s) return false;

  char tag[4];
  int i;
  s += strlen (prefix);
  for (i = 0; i < 4 && ISALNUM (s[i]); i++)
    tag[i] = normalize (s[i]);
  if (!i) return false;

  for (; i < 4; i++)
    tag[i] = ' ';
  tags[0] = HB_TAG (tag[0], tag[1], tag[2], tag[3]);
  if ((tags[0] & 0xDFDFDFDF) == HB_OT_TAG_DEFAULT_SCRIPT)
    tags[0] ^= ~0xDFDFDFDF;
  *count = 1;
  return true;
}

/**
 * hb_ot_tags_from_script_and_language:
 * @script: an #hb_script_t to convert.
 * @language: an #hb_language_t to convert.
 * @script_count: (allow-none): maximum number of script tags to retrieve (IN)
 * and actual number of script tags retrieved (OUT)
 * @script_tags: (out) (allow-none): array of size at least @script_count to store the
 * script tag results
 * @language_count: (allow-none): maximum number of language tags to retrieve
 * (IN) and actual number of language tags retrieved (OUT)
 * @language_tags: (out) (allow-none): array of size at least @language_count to store
 * the language tag results
 *
 * Converts an #hb_script_t and an #hb_language_t to script and language tags.
 *
 * Since: 2.0.0
 **/
void
hb_ot_tags_from_script_and_language (hb_script_t   script,
				     hb_language_t language,
				     unsigned int *script_count /* IN/OUT */,
				     hb_tag_t     *script_tags /* OUT */,
				     unsigned int *language_count /* IN/OUT */,
				     hb_tag_t     *language_tags /* OUT */)
{
  bool needs_script = true;

  if (language == HB_LANGUAGE_INVALID)
  {
    if (language_count && language_tags && *language_count)
      *language_count = 0;
  }
  else
  {
    const char *lang_str, *s, *limit, *private_use_subtag;
    bool needs_language;

    lang_str = hb_language_to_string (language);
    limit = nullptr;
    private_use_subtag = nullptr;
    if (lang_str[0] == 'x' && lang_str[1] == '-')
    {
      private_use_subtag = lang_str;
    } else {
      for (s = lang_str + 1; *s; s++)
      {
	if (s[-1] == '-' && s[1] == '-')
	{
	  if (s[0] == 'x')
	  {
	    private_use_subtag = s;
	    if (!limit)
	      limit = s - 1;
	    break;
	  } else if (!limit)
	  {
	    limit = s - 1;
	  }
	}
      }
      if (!limit)
	limit = s;
    }

    needs_script = !parse_private_use_subtag (private_use_subtag, script_count, script_tags, "-hbsc", TOLOWER);
    needs_language = !parse_private_use_subtag (private_use_subtag, language_count, language_tags, "-hbot", TOUPPER);

    if (needs_language && language_count && language_tags && *language_count)
      hb_ot_tags_from_language (lang_str, limit, language_count, language_tags);
  }

  if (needs_script && script_count && script_tags && *script_count)
    hb_ot_all_tags_from_script (script, script_count, script_tags);
}

/**
 * hb_ot_tag_to_language:
 *
 *
 *
 * Return value: (transfer none):
 *
 * Since: 0.9.2
 **/
hb_language_t
hb_ot_tag_to_language (hb_tag_t tag)
{
  unsigned int i;

  if (tag == HB_OT_TAG_DEFAULT_LANGUAGE)
    return nullptr;

  {
    hb_language_t disambiguated_tag = hb_ot_ambiguous_tag_to_language (tag);
    if (disambiguated_tag != HB_LANGUAGE_INVALID)
      return disambiguated_tag;
  }

  for (i = 0; i < ARRAY_LENGTH (ot_languages); i++)
    if (ot_languages[i].tag == tag)
      return hb_language_from_string (ot_languages[i].language, -1);

  /* If it's three letters long, assume it's ISO 639-3 and lower-case and use it
   * (if it's not a registered tag, calling hb_ot_tag_from_language on the
   * result might not return the same tag as the original tag).
   * Else return a custom language in the form of "x-hbotABCD". */
  {
    char buf[11] = "x-hbot";
    char *str = buf;
    buf[6] = tag >> 24;
    buf[7] = (tag >> 16) & 0xFF;
    buf[8] = (tag >> 8) & 0xFF;
    buf[9] = tag & 0xFF;
    if (buf[9] == 0x20)
    {
      buf[9] = '\0';
      if (ISALPHA (buf[6]) && ISALPHA (buf[7]) && ISALPHA (buf[8]))
      {
	buf[6] = TOLOWER (buf[6]);
	buf[7] = TOLOWER (buf[7]);
	buf[8] = TOLOWER (buf[8]);
	str += 6;
      }
    }
    buf[10] = '\0';
    return hb_language_from_string (str, -1);
  }
}

/**
 * hb_ot_tags_to_script_and_language:
 * @script_tag: a script tag
 * @language_tag: a language tag
 * @script: (allow-none): the #hb_script_t corresponding to @script_tag (OUT).
 * @language: (allow-none): the #hb_language_t corresponding to @script_tag and
 * @language_tag (OUT).
 *
 * Converts a script tag and a language tag to an #hb_script_t and an
 * #hb_language_t.
 *
 * Since: 2.0.0
 **/
void
hb_ot_tags_to_script_and_language (hb_tag_t       script_tag,
				   hb_tag_t       language_tag,
				   hb_script_t   *script /* OUT */,
				   hb_language_t *language /* OUT */)
{
  hb_script_t script_out = hb_ot_tag_to_script (script_tag);
  if (script)
    *script = script_out;
  if (language)
  {
    unsigned int script_count = 1;
    hb_tag_t primary_script_tag[1];
    hb_ot_tags_from_script_and_language (script_out,
					 HB_LANGUAGE_INVALID,
					 &script_count,
					 primary_script_tag,
					 nullptr, nullptr);
    *language = hb_ot_tag_to_language (language_tag);
    if (script_count == 0 || primary_script_tag[0] != script_tag)
    {
      unsigned char *buf;
      const char *lang_str = hb_language_to_string (*language);
      size_t len = strlen (lang_str);
      buf = (unsigned char *) malloc (len + 11);
      if (unlikely (!buf))
      {
	*language = nullptr;
      }
      else
      {
	memcpy (buf, lang_str, len);
	if (lang_str[0] != 'x' || lang_str[1] != '-') {
	  buf[len++] = '-';
	  buf[len++] = 'x';
	}
	buf[len++] = '-';
	buf[len++] = 'h';
	buf[len++] = 'b';
	buf[len++] = 's';
	buf[len++] = 'c';
	buf[len++] = script_tag >> 24;
	buf[len++] = (script_tag >> 16) & 0xFF;
	buf[len++] = (script_tag >> 8) & 0xFF;
	buf[len++] = script_tag & 0xFF;
	*language = hb_language_from_string ((char *) buf, len);
	free (buf);
      }
    }
  }
}

#ifdef MAIN
static inline void
test_langs_sorted ()
{
  for (unsigned int i = 1; i < ARRAY_LENGTH (ot_languages); i++)
  {
    int c = ot_languages[i].cmp (&ot_languages[i - 1]);
    if (c > 0)
    {
      fprintf (stderr, "ot_languages not sorted at index %d: %s %d %s\n",
	       i, ot_languages[i-1].language, c, ot_languages[i].language);
      abort();
    }
  }
}

int
main ()
{
  test_langs_sorted ();
  return 0;
}

#endif