harfbuzz/src/hb-ot-shape-complex-indic.hh

/*
 * Copyright © 2012  Google, Inc.
 *
 *  This is part of HarfBuzz, a text shaping library.
 *
 * Permission is hereby granted, without written agreement and without
 * license or royalty fees, to use, copy, modify, and distribute this
 * software and its documentation for any purpose, provided that the
 * above copyright notice and the following two paragraphs appear in
 * all copies of this software.
 *
 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 *
 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
 *
 * Google Author(s): Behdad Esfahbod
 */

#ifndef HB_OT_SHAPE_COMPLEX_INDIC_HH
#define HB_OT_SHAPE_COMPLEX_INDIC_HH

#include "hb.hh"

#include "hb-ot-shape-complex-syllabic.hh"


/* buffer var allocations */
#define indic_category() complex_var_u8_category() /* indic_category_t */
#define indic_position() complex_var_u8_auxiliary() /* indic_position_t */


/* Cateories used in the OpenType spec:
 * https://docs.microsoft.com/en-us/typography/script-development/devanagari
 */
/* Note: This enum is duplicated in the -machine.rl source file.
 * Not sure how to avoid duplication. */
enum indic_category_t {
  OT_X = 0,
  OT_C = 1,
  OT_V = 2,
  OT_N = 3,
  OT_H = 4,
  OT_ZWNJ = 5,
  OT_ZWJ = 6,
  OT_M = 7,
  OT_SM = 8,
  /* OT_VD = 9, UNUSED; we use OT_A instead. */
  OT_A = 10,
  OT_PLACEHOLDER = 11,
  OT_DOTTEDCIRCLE = 12,
  OT_RS = 13, /* Register Shifter, used in Khmer OT spec. */
  OT_Coeng = 14, /* Khmer-style Virama. */
  OT_Repha = 15, /* Atomically-encoded logical or visual repha. */
  OT_Ra = 16,
  OT_CM = 17,  /* Consonant-Medial. */
  OT_Symbol = 18, /* Avagraha, etc that take marks (SM,A,VD). */
  OT_CS = 19,

  /* The following are used by Khmer & Myanmar shapers.  Defined
   * here for them to share. */
  OT_VAbv    = 26,
  OT_VBlw    = 27,
  OT_VPre    = 28,
  OT_VPst    = 29,
};

#define MEDIAL_FLAGS (FLAG (OT_CM))

/* Note:
 *
 * We treat Vowels and placeholders as if they were consonants.  This is safe because Vowels
 * cannot happen in a consonant syllable.  The plus side however is, we can call the
 * consonant syllable logic from the vowel syllable function and get it all right! */
#define CONSONANT_FLAGS (FLAG (OT_C) | FLAG (OT_CS) | FLAG (OT_Ra) | MEDIAL_FLAGS | FLAG (OT_V) | FLAG (OT_PLACEHOLDER) | FLAG (OT_DOTTEDCIRCLE))
#define JOINER_FLAGS (FLAG (OT_ZWJ) | FLAG (OT_ZWNJ))


/* Visual positions in a syllable from left to right. */
enum indic_position_t {
  POS_START = 0,

  POS_RA_TO_BECOME_REPH = 1,
  POS_PRE_M = 2,
  POS_PRE_C = 3,

  POS_BASE_C = 4,
  POS_AFTER_MAIN = 5,

  POS_ABOVE_C = 6,

  POS_BEFORE_SUB = 7,
  POS_BELOW_C = 8,
  POS_AFTER_SUB = 9,

  POS_BEFORE_POST = 10,
  POS_POST_C = 11,
  POS_AFTER_POST = 12,

  POS_FINAL_C = 13,
  POS_SMVD = 14,

  POS_END = 15
};

/* Categories used in IndicSyllabicCategory.txt from UCD. */
enum indic_syllabic_category_t {
  INDIC_SYLLABIC_CATEGORY_OTHER				= OT_X,

  INDIC_SYLLABIC_CATEGORY_AVAGRAHA			= OT_Symbol,
  INDIC_SYLLABIC_CATEGORY_BINDU				= OT_SM,
  INDIC_SYLLABIC_CATEGORY_BRAHMI_JOINING_NUMBER		= OT_PLACEHOLDER, /* Don't care. */
  INDIC_SYLLABIC_CATEGORY_CANTILLATION_MARK		= OT_A,
  INDIC_SYLLABIC_CATEGORY_CONSONANT			= OT_C,
  INDIC_SYLLABIC_CATEGORY_CONSONANT_DEAD		= OT_C,
  INDIC_SYLLABIC_CATEGORY_CONSONANT_FINAL		= OT_CM,
  INDIC_SYLLABIC_CATEGORY_CONSONANT_HEAD_LETTER		= OT_C,
  INDIC_SYLLABIC_CATEGORY_CONSONANT_KILLER		= OT_M, /* U+17CD only. */
  INDIC_SYLLABIC_CATEGORY_CONSONANT_MEDIAL		= OT_CM,
  INDIC_SYLLABIC_CATEGORY_CONSONANT_PLACEHOLDER		= OT_PLACEHOLDER,
  INDIC_SYLLABIC_CATEGORY_CONSONANT_PRECEDING_REPHA	= OT_Repha,
  INDIC_SYLLABIC_CATEGORY_CONSONANT_PREFIXED		= OT_X, /* Don't care. */
  INDIC_SYLLABIC_CATEGORY_CONSONANT_SUBJOINED		= OT_CM,
  INDIC_SYLLABIC_CATEGORY_CONSONANT_SUCCEEDING_REPHA	= OT_CM,
  INDIC_SYLLABIC_CATEGORY_CONSONANT_WITH_STACKER	= OT_CS,
  INDIC_SYLLABIC_CATEGORY_GEMINATION_MARK		= OT_SM, /* https://github.com/harfbuzz/harfbuzz/issues/552 */
  INDIC_SYLLABIC_CATEGORY_INVISIBLE_STACKER		= OT_Coeng,
  INDIC_SYLLABIC_CATEGORY_JOINER			= OT_ZWJ,
  INDIC_SYLLABIC_CATEGORY_MODIFYING_LETTER		= OT_X,
  INDIC_SYLLABIC_CATEGORY_NON_JOINER			= OT_ZWNJ,
  INDIC_SYLLABIC_CATEGORY_NUKTA				= OT_N,
  INDIC_SYLLABIC_CATEGORY_NUMBER			= OT_PLACEHOLDER,
  INDIC_SYLLABIC_CATEGORY_NUMBER_JOINER			= OT_PLACEHOLDER, /* Don't care. */
  INDIC_SYLLABIC_CATEGORY_PURE_KILLER			= OT_M, /* Is like a vowel matra. */
  INDIC_SYLLABIC_CATEGORY_REGISTER_SHIFTER		= OT_RS,
  INDIC_SYLLABIC_CATEGORY_SYLLABLE_MODIFIER		= OT_SM,
  INDIC_SYLLABIC_CATEGORY_TONE_LETTER			= OT_X,
  INDIC_SYLLABIC_CATEGORY_TONE_MARK			= OT_N,
  INDIC_SYLLABIC_CATEGORY_VIRAMA			= OT_H,
  INDIC_SYLLABIC_CATEGORY_VISARGA			= OT_SM,
  INDIC_SYLLABIC_CATEGORY_VOWEL				= OT_V,
  INDIC_SYLLABIC_CATEGORY_VOWEL_DEPENDENT		= OT_M,
  INDIC_SYLLABIC_CATEGORY_VOWEL_INDEPENDENT		= OT_V
};

/* Categories used in IndicSMatraCategory.txt from UCD */
enum indic_matra_category_t {
  INDIC_MATRA_CATEGORY_NOT_APPLICABLE			= POS_END,

  INDIC_MATRA_CATEGORY_LEFT				= POS_PRE_C,
  INDIC_MATRA_CATEGORY_TOP				= POS_ABOVE_C,
  INDIC_MATRA_CATEGORY_BOTTOM				= POS_BELOW_C,
  INDIC_MATRA_CATEGORY_RIGHT				= POS_POST_C,

  /* These should resolve to the position of the last part of the split sequence. */
  INDIC_MATRA_CATEGORY_BOTTOM_AND_RIGHT			= INDIC_MATRA_CATEGORY_RIGHT,
  INDIC_MATRA_CATEGORY_LEFT_AND_RIGHT			= INDIC_MATRA_CATEGORY_RIGHT,
  INDIC_MATRA_CATEGORY_TOP_AND_BOTTOM			= INDIC_MATRA_CATEGORY_BOTTOM,
  INDIC_MATRA_CATEGORY_TOP_AND_BOTTOM_AND_LEFT		= INDIC_MATRA_CATEGORY_BOTTOM,
  INDIC_MATRA_CATEGORY_TOP_AND_BOTTOM_AND_RIGHT		= INDIC_MATRA_CATEGORY_RIGHT,
  INDIC_MATRA_CATEGORY_TOP_AND_LEFT			= INDIC_MATRA_CATEGORY_TOP,
  INDIC_MATRA_CATEGORY_TOP_AND_LEFT_AND_RIGHT		= INDIC_MATRA_CATEGORY_RIGHT,
  INDIC_MATRA_CATEGORY_TOP_AND_RIGHT			= INDIC_MATRA_CATEGORY_RIGHT,

  INDIC_MATRA_CATEGORY_OVERSTRUCK			= POS_AFTER_MAIN,
  INDIC_MATRA_CATEGORY_VISUAL_ORDER_LEFT		= POS_PRE_M
};

#define INDIC_COMBINE_CATEGORIES(S,M) \
  ( \
    static_assert_expr (S < 255 && M < 255) + \
    ( S | \
     ( \
      ( \
       S == INDIC_SYLLABIC_CATEGORY_CONSONANT_MEDIAL || \
       S == INDIC_SYLLABIC_CATEGORY_GEMINATION_MARK || \
       S == INDIC_SYLLABIC_CATEGORY_REGISTER_SHIFTER || \
       S == INDIC_SYLLABIC_CATEGORY_CONSONANT_SUCCEEDING_REPHA || \
       S == INDIC_SYLLABIC_CATEGORY_VIRAMA || \
       S == INDIC_SYLLABIC_CATEGORY_VOWEL_DEPENDENT || \
       false \
       ? M : INDIC_MATRA_CATEGORY_NOT_APPLICABLE \
      ) << 8 \
     ) \
    ) \
   )

HB_INTERNAL uint16_t
hb_indic_get_categories (hb_codepoint_t u);


static inline bool
is_one_of (const hb_glyph_info_t &info, unsigned int flags)
{
  /* If it ligated, all bets are off. */
  if (_hb_glyph_info_ligated (&info)) return false;
  return !!(FLAG_UNSAFE (info.indic_category()) & flags);
}

static inline bool
is_joiner (const hb_glyph_info_t &info)
{
  return is_one_of (info, JOINER_FLAGS);
}

static inline bool
is_consonant (const hb_glyph_info_t &info)
{
  return is_one_of (info, CONSONANT_FLAGS);
}

static inline bool
is_halant (const hb_glyph_info_t &info)
{
  return is_one_of (info, FLAG (OT_H));
}

#define IN_HALF_BLOCK(u, Base) (((u) & ~0x7Fu) == (Base))

#define IS_DEVA(u) (IN_HALF_BLOCK (u, 0x0900u))
#define IS_BENG(u) (IN_HALF_BLOCK (u, 0x0980u))
#define IS_GURU(u) (IN_HALF_BLOCK (u, 0x0A00u))
#define IS_GUJR(u) (IN_HALF_BLOCK (u, 0x0A80u))
#define IS_ORYA(u) (IN_HALF_BLOCK (u, 0x0B00u))
#define IS_TAML(u) (IN_HALF_BLOCK (u, 0x0B80u))
#define IS_TELU(u) (IN_HALF_BLOCK (u, 0x0C00u))
#define IS_KNDA(u) (IN_HALF_BLOCK (u, 0x0C80u))
#define IS_MLYM(u) (IN_HALF_BLOCK (u, 0x0D00u))
#define IS_SINH(u) (IN_HALF_BLOCK (u, 0x0D80u))


#define MATRA_POS_LEFT(u)	POS_PRE_M
#define MATRA_POS_RIGHT(u)	( \
				  IS_DEVA(u) ? POS_AFTER_SUB  : \
				  IS_BENG(u) ? POS_AFTER_POST : \
				  IS_GURU(u) ? POS_AFTER_POST : \
				  IS_GUJR(u) ? POS_AFTER_POST : \
				  IS_ORYA(u) ? POS_AFTER_POST : \
				  IS_TAML(u) ? POS_AFTER_POST : \
				  IS_TELU(u) ? (u <= 0x0C42u ? POS_BEFORE_SUB : POS_AFTER_SUB) : \
				  IS_KNDA(u) ? (u < 0x0CC3u || u > 0xCD6u ? POS_BEFORE_SUB : POS_AFTER_SUB) : \
				  IS_MLYM(u) ? POS_AFTER_POST : \
				  IS_SINH(u) ? POS_AFTER_SUB  : \
				  /*default*/  POS_AFTER_SUB    \
				)
#define MATRA_POS_TOP(u)	( /* BENG and MLYM don't have top matras. */ \
				  IS_DEVA(u) ? POS_AFTER_SUB  : \
				  IS_GURU(u) ? POS_AFTER_POST : /* Deviate from spec */ \
				  IS_GUJR(u) ? POS_AFTER_SUB  : \
				  IS_ORYA(u) ? POS_AFTER_MAIN : \
				  IS_TAML(u) ? POS_AFTER_SUB  : \
				  IS_TELU(u) ? POS_BEFORE_SUB : \
				  IS_KNDA(u) ? POS_BEFORE_SUB : \
				  IS_SINH(u) ? POS_AFTER_SUB  : \
				  /*default*/  POS_AFTER_SUB    \
				)
#define MATRA_POS_BOTTOM(u)	( \
				  IS_DEVA(u) ? POS_AFTER_SUB  : \
				  IS_BENG(u) ? POS_AFTER_SUB  : \
				  IS_GURU(u) ? POS_AFTER_POST : \
				  IS_GUJR(u) ? POS_AFTER_POST : \
				  IS_ORYA(u) ? POS_AFTER_SUB  : \
				  IS_TAML(u) ? POS_AFTER_POST : \
				  IS_TELU(u) ? POS_BEFORE_SUB : \
				  IS_KNDA(u) ? POS_BEFORE_SUB : \
				  IS_MLYM(u) ? POS_AFTER_POST : \
				  IS_SINH(u) ? POS_AFTER_SUB  : \
				  /*default*/  POS_AFTER_SUB    \
				)

static inline indic_position_t
matra_position_indic (hb_codepoint_t u, indic_position_t side)
{
  switch ((int) side)
  {
    case POS_PRE_C:	return MATRA_POS_LEFT (u);
    case POS_POST_C:	return MATRA_POS_RIGHT (u);
    case POS_ABOVE_C:	return MATRA_POS_TOP (u);
    case POS_BELOW_C:	return MATRA_POS_BOTTOM (u);
  }
  return side;
}

/* XXX
 * This is a hack for now.  We should move this data into the main Indic table.
 * Or completely remove it and just check in the tables.
 */
static const hb_codepoint_t ra_chars[] = {
  0x0930u, /* Devanagari */
  0x09B0u, /* Bengali */
  0x09F0u, /* Bengali */
  0x0A30u, /* Gurmukhi */	/* No Reph */
  0x0AB0u, /* Gujarati */
  0x0B30u, /* Oriya */
  0x0BB0u, /* Tamil */		/* No Reph */
  0x0C30u, /* Telugu */		/* Reph formed only with ZWJ */
  0x0CB0u, /* Kannada */
  0x0D30u, /* Malayalam */	/* No Reph, Logical Repha */

  0x0DBBu, /* Sinhala */	/* Reph formed only with ZWJ */
};

static inline bool
is_ra (hb_codepoint_t u)
{
  return hb_array (ra_chars).lfind (u);
}

static inline void
set_indic_properties (hb_glyph_info_t &info)
{
  hb_codepoint_t u = info.codepoint;
  unsigned int type = hb_indic_get_categories (u);
  indic_category_t cat = (indic_category_t) (type & 0xFFu);
  indic_position_t pos = (indic_position_t) (type >> 8);


  /*
   * Re-assign category
   */

  /* The following act more like the Bindus. */
  if (unlikely (hb_in_range<hb_codepoint_t> (u, 0x0953u, 0x0954u)))
    cat = OT_SM;
  /* The following act like consonants. */
  else if (unlikely (hb_in_ranges<hb_codepoint_t> (u, 0x0A72u, 0x0A73u,
				      0x1CF5u, 0x1CF6u)))
    cat = OT_C;
  /* TODO: The following should only be allowed after a Visarga.
   * For now, just treat them like regular tone marks. */
  else if (unlikely (hb_in_range<hb_codepoint_t> (u, 0x1CE2u, 0x1CE8u)))
    cat = OT_A;
  /* TODO: The following should only be allowed after some of
   * the nasalization marks, maybe only for U+1CE9..U+1CF1.
   * For now, just treat them like tone marks. */
  else if (unlikely (u == 0x1CEDu))
    cat = OT_A;
  /* The following take marks in standalone clusters, similar to Avagraha. */
  else if (unlikely (hb_in_ranges<hb_codepoint_t> (u, 0xA8F2u, 0xA8F7u,
				      0x1CE9u, 0x1CECu,
				      0x1CEEu, 0x1CF1u)))
  {
    cat = OT_Symbol;
    static_assert (((int) INDIC_SYLLABIC_CATEGORY_AVAGRAHA == OT_Symbol), "");
  }
  else if (unlikely (u == 0x0A51u))
  {
    /* https://github.com/harfbuzz/harfbuzz/issues/524 */
    cat = OT_M;
    pos = POS_BELOW_C;
  }

  /* According to ScriptExtensions.txt, these Grantha marks may also be used in Tamil,
   * so the Indic shaper needs to know their categories. */
  else if (unlikely (u == 0x11301u || u == 0x11303u)) cat = OT_SM;
  else if (unlikely (u == 0x1133Bu || u == 0x1133Cu)) cat = OT_N;

  else if (unlikely (u == 0x0AFBu)) cat = OT_N; /* https://github.com/harfbuzz/harfbuzz/issues/552 */
  else if (unlikely (u == 0x0B55u)) cat = OT_N; /* https://github.com/harfbuzz/harfbuzz/issues/2849 */

  else if (unlikely (u == 0x0980u)) cat = OT_PLACEHOLDER; /* https://github.com/harfbuzz/harfbuzz/issues/538 */
  else if (unlikely (u == 0x09FCu)) cat = OT_PLACEHOLDER; /* https://github.com/harfbuzz/harfbuzz/pull/1613 */
  else if (unlikely (u == 0x0C80u)) cat = OT_PLACEHOLDER; /* https://github.com/harfbuzz/harfbuzz/pull/623 */
  else if (unlikely (u == 0x0D04u)) cat = OT_PLACEHOLDER; /* https://github.com/harfbuzz/harfbuzz/pull/3511 */
  else if (unlikely (hb_in_range<hb_codepoint_t> (u, 0x2010u, 0x2011u)))
				    cat = OT_PLACEHOLDER;
  else if (unlikely (u == 0x25CCu)) cat = OT_DOTTEDCIRCLE;


  /*
   * Re-assign position.
   */

  if ((FLAG_UNSAFE (cat) & CONSONANT_FLAGS))
  {
    pos = POS_BASE_C;
    if (is_ra (u))
      cat = OT_Ra;
  }
  else if (cat == OT_M)
  {
    pos = matra_position_indic (u, pos);
  }
  else if ((FLAG_UNSAFE (cat) & (FLAG (OT_SM) /* | FLAG (OT_VD) */ | FLAG (OT_A) | FLAG (OT_Symbol))))
  {
    pos = POS_SMVD;
  }

  if (unlikely (u == 0x0B01u)) pos = POS_BEFORE_SUB; /* Oriya Bindu is BeforeSub in the spec. */



  info.indic_category() = cat;
  info.indic_position() = pos;
}

struct hb_indic_would_substitute_feature_t
{
  void init (const hb_ot_map_t *map, hb_tag_t feature_tag, bool zero_context_)
  {
    zero_context = zero_context_;
    map->get_stage_lookups (0/*GSUB*/,
			    map->get_feature_stage (0/*GSUB*/, feature_tag),
			    &lookups, &count);
  }

  bool would_substitute (const hb_codepoint_t *glyphs,
			 unsigned int          glyphs_count,
			 hb_face_t            *face) const
  {
    for (unsigned int i = 0; i < count; i++)
      if (hb_ot_layout_lookup_would_substitute (face, lookups[i].index, glyphs, glyphs_count, zero_context))
	return true;
    return false;
  }

  private:
  const hb_ot_map_t::lookup_map_t *lookups;
  unsigned int count;
  bool zero_context;
};


#endif /* HB_OT_SHAPE_COMPLEX_INDIC_HH */