harfbuzz/src/hb-ot-shape-complex-myanmar.cc

/*
 * Copyright © 2011,2012,2013  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
 */

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

/* buffer var allocations */
#define myanmar_category() complex_var_u8_0() /* myanmar_category_t */
#define myanmar_position() complex_var_u8_1() /* myanmar_matra_category_t */


/*
 * Myanmar shaper.
 */

static const hb_tag_t
myanmar_features[] =
{
  /*
   * Basic features.
   * These features are applied in order, one at a time, after initial_reordering.
   */
  HB_TAG('r','p','h','f'),
  HB_TAG('p','r','e','f'),
  HB_TAG('b','l','w','f'),
  HB_TAG('p','s','t','f'),
  /*
   * Other features.
   * These features are applied all at once, after final_reordering.
   */
  HB_TAG('p','r','e','s'),
  HB_TAG('a','b','v','s'),
  HB_TAG('b','l','w','s'),
  HB_TAG('p','s','t','s'),
  /* Positioning features, though we don't care about the types. */
  HB_TAG('d','i','s','t'),
};

/*
 * Must be in the same order as the myanmar_features array.
 */
enum {
  _RPHF,
  _PREF,
  _BLWF,
  _PSTF,

  _PRES,
  _ABVS,
  _BLWS,
  _PSTS,
  _DIST,

  MYANMAR_NUM_FEATURES,
  MYANMAR_BASIC_FEATURES = _PRES /* Don't forget to update this! */
};

static void
setup_syllables (const hb_ot_shape_plan_t *plan,
		 hb_font_t *font,
		 hb_buffer_t *buffer);
static void
initial_reordering (const hb_ot_shape_plan_t *plan,
		    hb_font_t *font,
		    hb_buffer_t *buffer);
static void
final_reordering (const hb_ot_shape_plan_t *plan,
		  hb_font_t *font,
		  hb_buffer_t *buffer);

static void
collect_features_myanmar (hb_ot_shape_planner_t *plan)
{
  hb_ot_map_builder_t *map = &plan->map;

  /* Do this before any lookups have been applied. */
  map->add_gsub_pause (setup_syllables);

  map->add_bool_feature (HB_TAG('l','o','c','l'));
  /* The Indic specs do not require ccmp, but we apply it here since if
   * there is a use of it, it's typically at the beginning. */
  map->add_bool_feature (HB_TAG('c','c','m','p'));


  unsigned int i = 0;
  map->add_gsub_pause (initial_reordering);
  for (; i < MYANMAR_BASIC_FEATURES; i++) {
    map->add_bool_feature (myanmar_features[i]);
    map->add_gsub_pause (NULL);
  }
  map->add_gsub_pause (final_reordering);
  for (; i < MYANMAR_NUM_FEATURES; i++) {
    map->add_bool_feature (myanmar_features[i]);
  }
}

static void
override_features_myanmar (hb_ot_shape_planner_t *plan)
{
  plan->map.add_feature (HB_TAG('l','i','g','a'), 0, true);
}


enum syllable_type_t {
  consonant_syllable,
  broken_cluster,
  non_myanmar_cluster,
};

#include "hb-ot-shape-complex-myanmar-machine.hh"


/* Note: This enum is duplicated in the -machine.rl source file.
 * Not sure how to avoid duplication. */
enum myanmar_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_A    = 10,
  OT_NBSP = 11,
  OT_DOTTEDCIRCLE = 12, /* Not in the spec, but special in Uniscribe. /Very very/ special! */

  OT_Ra = 16, /* Not explicitly listed in the OT spec, but used in the grammar. */
  OT_CM = 17, /* Generic Consonant_Medial; NOT used for Myanmar. */

  /* Myanmar OT spec types */

  OT_As  = 18, /* Asat */
  OT_D   = 19, /* Digits except zero */
  OT_D0  = 20, /* Digit zero */
  OT_DB  = OT_N, /* Dot below */
  OT_MH  = 21, /* Various consonant medial types */
  OT_MR  = 22, /* Various consonant medial types */
  OT_MW  = 23, /* Various consonant medial types */
  OT_MY  = 24, /* Various consonant medial types */
  OT_PT  = 25, /* Pwo and other tones */
  OT_VAbv = 26,
  OT_VBlw = 27,
  OT_VPre = 28,
  OT_VPst = 29,
  OT_VS   = 30 /* Variation selectors */
};

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

  POS_RA_TO_BECOME_REPH,
  POS_PRE_M,
  POS_PRE_C,

  POS_BASE_C,
  POS_AFTER_MAIN,

  POS_ABOVE_C,

  POS_BEFORE_SUB,
  POS_BELOW_C,
  POS_AFTER_SUB,

  POS_BEFORE_POST,
  POS_POST_C,
  POS_AFTER_POST,

  POS_FINAL_C,
  POS_SMVD,

  POS_END
};


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

/* 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_CM) | FLAG (OT_Ra) | FLAG (OT_V) | FLAG (OT_NBSP) | FLAG (OT_DOTTEDCIRCLE))
static inline bool
is_consonant (const hb_glyph_info_t &info)
{
  return is_one_of (info, CONSONANT_FLAGS);
}


static inline void
set_myanmar_properties (hb_glyph_info_t &info)
{
  hb_codepoint_t u = info.codepoint;
  myanmar_category_t cat = OT_C;
  myanmar_position_t pos = POS_BASE_C;

  /* Myanmar
   * http://www.microsoft.com/typography/OpenTypeDev/myanmar/intro.htm#analyze
   */
  if (unlikely (hb_in_range<hb_codepoint_t> (u, 0xFE00, 0xFE0F)))
    cat = OT_VS;
  switch (u)
  {
    case 0x1004: case 0x101B: case 0x105A:
      cat = OT_Ra;
      break;

    case 0x1032: case 0x1036:
      cat = OT_A;
      break;

    case 0x1039:
      cat = OT_H;
      break;

    case 0x103A:
      cat = OT_As;
      break;

    case 0x1041: case 0x1042: case 0x1043: case 0x1044:
    case 0x1045: case 0x1046: case 0x1047: case 0x1048:
    case 0x1049: case 0x1090: case 0x1091: case 0x1092:
    case 0x1093: case 0x1094: case 0x1095: case 0x1096:
    case 0x1097: case 0x1098: case 0x1099:
      cat = OT_D;
      break;

    case 0x1040:
      cat = OT_D; /* XXX The spec says D0, but Uniscribe doesn't seem to do. */
      break;

    case 0x1037:
      cat = OT_DB;
      break;

    case 0x103E: case 0x1060:
      cat = OT_MH;
      break;

    case 0x103C:
      cat = OT_MR;
      break;

    case 0x103D: case 0x1082:
      cat = OT_MW;
      break;

    case 0x103B: case 0x105E: case 0x105F:
      cat = OT_MY;
      break;

    case 0x1063: case 0x1064: case 0x1069: case 0x106A:
    case 0x106B: case 0x106C: case 0x106D: case 0xAA7B:
      cat = OT_PT;
      break;

    case 0x1038: case 0x1087: case 0x1088: case 0x1089:
    case 0x108A: case 0x108B: case 0x108C: case 0x108D:
    case 0x108F: case 0x109A: case 0x109B: case 0x109C:
      cat = OT_SM;
      break;

    case 0x102D: case 0x102E: case 0x1033: case 0x1034:
    case 0x1035: case 0x1071: case 0x1072: case 0x1073:
    case 0x1074: case 0x1085: case 0x1086: case 0x109D:
      cat = OT_VAbv;
      break;

    case 0x102F: case 0x1030: case 0x1058: case 0x1059:
      cat = OT_VBlw;
      break;

    case 0x1031: case 0x1084:
      cat = OT_VPre;
      pos = POS_PRE_M;
      break;

    case 0x102B: case 0x102C: case 0x1056: case 0x1057:
    case 0x1062: case 0x1067: case 0x1068: case 0x1083:
      cat = OT_VPst;
      break;
  }

  info.myanmar_category() = cat;
  info.myanmar_position() = pos;
}



static void
setup_masks_myanmar (const hb_ot_shape_plan_t *plan HB_UNUSED,
		   hb_buffer_t              *buffer,
		   hb_font_t                *font HB_UNUSED)
{
  HB_BUFFER_ALLOCATE_VAR (buffer, myanmar_category);
  HB_BUFFER_ALLOCATE_VAR (buffer, myanmar_position);

  /* We cannot setup masks here.  We save information about characters
   * and setup masks later on in a pause-callback. */

  unsigned int count = buffer->len;
  for (unsigned int i = 0; i < count; i++)
    set_myanmar_properties (buffer->info[i]);
}

static void
setup_syllables (const hb_ot_shape_plan_t *plan HB_UNUSED,
		 hb_font_t *font HB_UNUSED,
		 hb_buffer_t *buffer)
{
  find_syllables (buffer);
}

static int
compare_myanmar_order (const hb_glyph_info_t *pa, const hb_glyph_info_t *pb)
{
  int a = pa->myanmar_position();
  int b = pb->myanmar_position();

  return a < b ? -1 : a == b ? 0 : +1;
}


/* Rules from:
 * http://www.microsoft.com/typography/OpenTypeDev/myanmar/intro.htm */

static void
initial_reordering_consonant_syllable (const hb_ot_shape_plan_t *plan,
				       hb_face_t *face,
				       hb_buffer_t *buffer,
				       unsigned int start, unsigned int end)
{
  hb_glyph_info_t *info = buffer->info;

  unsigned int base = end;
  bool has_reph = false;

  {
    unsigned int limit = start;
    if (start + 3 <= end &&
	info[start  ].myanmar_category() == OT_Ra &&
	info[start+1].myanmar_category() == OT_As &&
	info[start+2].myanmar_category() == OT_H)
    {
      limit += 3;
      base = start;
      has_reph = true;
    }

    {
      if (!has_reph)
	base = limit;

      for (unsigned int i = limit; i < end; i++)
	if (is_consonant (info[i]))
	{
	  base = i;
	  break;
	}
    }
  }

  /* Reorder! */
  {
    unsigned int i = start;
    for (; i < start + (has_reph ? 3 : 0); i++)
      info[i].myanmar_position() = POS_AFTER_MAIN;
    for (; i < base; i++)
      info[i].myanmar_position() = POS_PRE_C;
    if (i < end)
    {
      info[i].myanmar_position() = POS_BASE_C;
      i++;
    }
    myanmar_position_t pos = POS_AFTER_MAIN;
    /* The following loop may be ugly, but it implements all of
     * Myanmar reordering! */
    for (; i < end; i++)
    {
      if (info[i].myanmar_category() == OT_MR) /* Pre-base reordering */
      {
	info[i].myanmar_position() = POS_PRE_C;
	continue;
      }
      if (info[i].myanmar_position() < POS_BASE_C) /* Left matra */
      {
	continue;
      }

      if (pos == POS_AFTER_MAIN && info[i].myanmar_category() == OT_VBlw)
      {
	pos = POS_BELOW_C;
	info[i].myanmar_position() = pos;
	continue;
      }

      if (pos == POS_BELOW_C && info[i].myanmar_category() == OT_A)
      {
	info[i].myanmar_position() = POS_BEFORE_SUB;
	continue;
      }
      if (pos == POS_BELOW_C && info[i].myanmar_category() == OT_VBlw)
      {
	info[i].myanmar_position() = pos;
	continue;
      }
      if (pos == POS_BELOW_C && info[i].myanmar_category() != OT_A)
      {
        pos = POS_AFTER_SUB;
	info[i].myanmar_position() = pos;
	continue;
      }
      info[i].myanmar_position() = pos;
    }
  }

  buffer->merge_clusters (start, end);
  /* Sit tight, rock 'n roll! */
  hb_bubble_sort (info + start, end - start, compare_myanmar_order);
}

static void
initial_reordering_broken_cluster (const hb_ot_shape_plan_t *plan,
				   hb_face_t *face,
				   hb_buffer_t *buffer,
				   unsigned int start, unsigned int end)
{
  /* We already inserted dotted-circles, so just call the consonant_syllable. */
  initial_reordering_consonant_syllable (plan, face, buffer, start, end);
}

static void
initial_reordering_non_myanmar_cluster (const hb_ot_shape_plan_t *plan HB_UNUSED,
					hb_face_t *face HB_UNUSED,
					hb_buffer_t *buffer HB_UNUSED,
					unsigned int start HB_UNUSED, unsigned int end HB_UNUSED)
{
  /* Nothing to do right now.  If we ever switch to using the output
   * buffer in the reordering process, we'd need to next_glyph() here. */
}


static void
initial_reordering_syllable (const hb_ot_shape_plan_t *plan,
			     hb_face_t *face,
			     hb_buffer_t *buffer,
			     unsigned int start, unsigned int end)
{
  syllable_type_t syllable_type = (syllable_type_t) (buffer->info[start].syllable() & 0x0F);
  switch (syllable_type) {
  case consonant_syllable:	initial_reordering_consonant_syllable  (plan, face, buffer, start, end); return;
  case broken_cluster:		initial_reordering_broken_cluster      (plan, face, buffer, start, end); return;
  case non_myanmar_cluster:	initial_reordering_non_myanmar_cluster (plan, face, buffer, start, end); return;
  }
}

static inline void
insert_dotted_circles (const hb_ot_shape_plan_t *plan HB_UNUSED,
		       hb_font_t *font,
		       hb_buffer_t *buffer)
{
  /* Note: This loop is extra overhead, but should not be measurable. */
  bool has_broken_syllables = false;
  unsigned int count = buffer->len;
  for (unsigned int i = 0; i < count; i++)
    if ((buffer->info[i].syllable() & 0x0F) == broken_cluster) {
      has_broken_syllables = true;
      break;
    }
  if (likely (!has_broken_syllables))
    return;


  hb_codepoint_t dottedcircle_glyph;
  if (!font->get_glyph (0x25CC, 0, &dottedcircle_glyph))
    return;

  hb_glyph_info_t dottedcircle = {0};
  dottedcircle.codepoint = 0x25CC;
  set_myanmar_properties (dottedcircle);
  dottedcircle.codepoint = dottedcircle_glyph;

  buffer->clear_output ();

  buffer->idx = 0;
  unsigned int last_syllable = 0;
  while (buffer->idx < buffer->len)
  {
    unsigned int syllable = buffer->cur().syllable();
    syllable_type_t syllable_type = (syllable_type_t) (syllable & 0x0F);
    if (unlikely (last_syllable != syllable && syllable_type == broken_cluster))
    {
      last_syllable = syllable;

      hb_glyph_info_t info = dottedcircle;
      info.cluster = buffer->cur().cluster;
      info.mask = buffer->cur().mask;
      info.syllable() = buffer->cur().syllable();

      buffer->output_info (info);
    }
    else
      buffer->next_glyph ();
  }

  buffer->swap_buffers ();
}

static void
initial_reordering (const hb_ot_shape_plan_t *plan,
		    hb_font_t *font,
		    hb_buffer_t *buffer)
{
  insert_dotted_circles (plan, font, buffer);

  hb_glyph_info_t *info = buffer->info;
  unsigned int count = buffer->len;
  if (unlikely (!count)) return;
  unsigned int last = 0;
  unsigned int last_syllable = info[0].syllable();
  for (unsigned int i = 1; i < count; i++)
    if (last_syllable != info[i].syllable()) {
      initial_reordering_syllable (plan, font->face, buffer, last, i);
      last = i;
      last_syllable = info[last].syllable();
    }
  initial_reordering_syllable (plan, font->face, buffer, last, count);
}

static void
final_reordering (const hb_ot_shape_plan_t *plan,
		  hb_font_t *font HB_UNUSED,
		  hb_buffer_t *buffer)
{
  hb_glyph_info_t *info = buffer->info;
  unsigned int count = buffer->len;

  /* Zero syllables now... */
  for (unsigned int i = 0; i < count; i++)
    info[i].syllable() = 0;

  HB_BUFFER_DEALLOCATE_VAR (buffer, myanmar_category);
  HB_BUFFER_DEALLOCATE_VAR (buffer, myanmar_position);
}


static hb_ot_shape_normalization_mode_t
normalization_preference_myanmar (const hb_segment_properties_t *props HB_UNUSED)
{
  return HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS_NO_SHORT_CIRCUIT;
}


const hb_ot_complex_shaper_t _hb_ot_complex_shaper_myanmar =
{
  "myanmar",
  collect_features_myanmar,
  override_features_myanmar,
  NULL, /* data_create */
  NULL, /* data_destroy */
  NULL, /* preprocess_text */
  normalization_preference_myanmar,
  NULL, /* decompose */
  NULL, /* compose */
  setup_masks_myanmar,
  false, /* zero_width_attached_marks */
  false, /* fallback_position */
};