[Indic] Apply Indic features
Find the base consonant and apply basic Indic features accordingly. Nothing complete, but does something for now. Specifically: no Ra handling right now, and no ZWJ/ZWNJ. Number of failing shape-complex tests goes from 174 down to 125. Next: reorder matras.
This commit is contained in:
Behdad Esfahbod
parent
1a1b501315
commit
743807a3ce
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@ -59,15 +59,17 @@ z = ZWJ|ZWNJ;
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matra_group = M N? H?;
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syllable_tail = SM? (VD VD?)?;
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action found_syllable {
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found_syllable (map, buffer, last, p);
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last = p;
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}
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action found_consonant_syllable { found_consonant_syllable (map, buffer, mask_array, last, p); }
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action found_vowel_syllable { found_vowel_syllable (map, buffer, mask_array, last, p); }
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action found_standalone_cluster { found_standalone_cluster (map, buffer, mask_array, last, p); }
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action found_non_indic { found_non_indic (map, buffer, mask_array, last, p); }
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consonant_syllable = (c.N? (z.H|H.z?))* c.N? A? (H.z? | matra_group*)? syllable_tail %(found_syllable);
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vowel_syllable = (Ra H)? V N? (z.H.c | ZWJ.c)? matra_group* syllable_tail;
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standalone_cluster = (Ra H)? NBSP N? (z? H c)? matra_group* syllable_tail;
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non_indic = X;
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action next_syllable { set_cluster (buffer, p, last); last = p; }
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consonant_syllable = (c.N? (z.H|H.z?))* c.N? A? (H.z? | matra_group*)? syllable_tail %(found_consonant_syllable);
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vowel_syllable = (Ra H)? V N? (z.H.c | ZWJ.c)? matra_group* syllable_tail %(found_vowel_syllable);
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standalone_cluster = (Ra H)? NBSP N? (z? H c)? matra_group* syllable_tail %(found_standalone_cluster);
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non_indic = X %(found_non_indic);
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syllable =
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consonant_syllable
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@ -76,16 +78,25 @@ syllable =
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| non_indic
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;
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main := syllable**;
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main := (syllable %(next_syllable))**;
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}%%
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#include <stdio.h>
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#include <string.h>
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static void
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set_cluster (hb_buffer_t *buffer,
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unsigned int start, unsigned int end)
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{
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unsigned int cluster = buffer->info[start].cluster;
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for (unsigned int i = start + 1; i < end; i++)
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cluster = MIN (cluster, buffer->info[i].cluster);
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for (unsigned int i = start; i < end; i++)
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buffer->info[i].cluster = cluster;
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}
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static void
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find_syllables (hb_ot_map_t *map, hb_buffer_t *buffer)
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find_syllables (const hb_ot_map_t *map, hb_buffer_t *buffer, hb_mask_t *mask_array)
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{
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unsigned int p, pe, eof;
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int cs;
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@ -136,7 +136,7 @@ enum indic_matra_category_t {
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* and/or
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* 2. Probe font lookups to determine consonant positions.
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*/
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static const struct {
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static const struct consonant_position_t {
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hb_codepoint_t u;
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indic_position_t position;
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} consonant_positions[] = {
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@ -236,6 +236,28 @@ static const struct {
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{0x0D35, POS_POST},
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};
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static int
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compare_codepoint (const void *pa, const void *pb)
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{
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hb_codepoint_t a = * (hb_codepoint_t *) pa;
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hb_codepoint_t b = * (hb_codepoint_t *) pb;
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return a < b ? -1 : a == b ? 0 : +1;
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}
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static indic_position_t
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consonant_position (hb_codepoint_t u)
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{
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consonant_position_t *record;
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record = (consonant_position_t *) bsearch (&u, consonant_positions,
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ARRAY_LENGTH (consonant_positions),
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sizeof (consonant_positions[0]),
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compare_codepoint);
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return record ? record->position : POS_BASE;
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}
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static const struct {
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hb_tag_t tag;
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@ -281,16 +303,17 @@ static const hb_tag_t indic_other_features[] =
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HB_TAG('b','l','w','m'),
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};
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static void
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initial_reordering (const hb_ot_map_t *map,
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hb_face_t *face,
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hb_buffer_t *buffer,
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void *user_data HB_UNUSED);
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static void
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final_reordering (const hb_ot_map_t *map,
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hb_face_t *face,
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hb_buffer_t *buffer,
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void *user_data HB_UNUSED)
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{
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HB_BUFFER_DEALLOCATE_VAR (buffer, indic_category);
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HB_BUFFER_DEALLOCATE_VAR (buffer, indic_position);
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}
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void *user_data HB_UNUSED);
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void
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_hb_ot_shape_complex_collect_features_indic (hb_ot_map_builder_t *map, const hb_segment_properties_t *props)
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@ -300,7 +323,7 @@ _hb_ot_shape_complex_collect_features_indic (hb_ot_map_builder_t *map, const hb_
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* there is a use of it, it's typically at the beginning. */
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map->add_bool_feature (HB_TAG('c','c','m','p'));
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map->add_gsub_pause (NULL, NULL);
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map->add_gsub_pause (initial_reordering, NULL);
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for (unsigned int i = 0; i < ARRAY_LENGTH (indic_basic_features); i++)
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map->add_bool_feature (indic_basic_features[i].tag, indic_basic_features[i].is_global);
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@ -319,39 +342,185 @@ _hb_ot_shape_complex_prefer_decomposed_indic (void)
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return TRUE;
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}
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static void
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found_syllable (hb_ot_map_t *map, hb_buffer_t *buffer,
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unsigned int start, unsigned int end)
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{
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//fprintf (stderr, "%d %d\n", start, end);
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}
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#include "hb-ot-shape-complex-indic-machine.hh"
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void
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_hb_ot_shape_complex_setup_masks_indic (hb_ot_map_t *map, hb_buffer_t *buffer)
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{
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unsigned int count = buffer->len;
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HB_BUFFER_ALLOCATE_VAR (buffer, indic_category);
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HB_BUFFER_ALLOCATE_VAR (buffer, indic_position);
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/* We cannot setup masks here. We save information about characters
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* and setup masks later on in a pause-callback. */
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unsigned int count = buffer->len;
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for (unsigned int i = 0; i < count; i++)
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{
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unsigned int type = get_indic_categories (buffer->info[i].codepoint);
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buffer->info[i].indic_category() = type & 0x0F;
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buffer->info[i].indic_position() = type >> 4;
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if (buffer->info[i].indic_category() == OT_C)
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buffer->info[i].indic_position() = consonant_position (buffer->info[i].codepoint);
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}
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}
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static void
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found_consonant_syllable (const hb_ot_map_t *map, hb_buffer_t *buffer, hb_mask_t *mask_array,
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unsigned int start, unsigned int end)
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{
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unsigned int i;
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/* Comments from:
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* https://www.microsoft.com/typography/otfntdev/devanot/shaping.aspx */
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/* 1. Find base consonant:
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*
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* The shaping engine finds the base consonant of the syllable, using the
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* following algorithm: starting from the end of the syllable, move backwards
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* until a consonant is found that does not have a below-base or post-base
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* form (post-base forms have to follow below-base forms), or that is not a
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* pre-base reordering Ra, or arrive at the first consonant. The consonant
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* stopped at will be the base.
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*
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* o If the syllable starts with Ra + Halant (in a script that has Reph)
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* and has more than one consonant, Ra is excluded from candidates for
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* base consonants.
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*/
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unsigned int base = 0;
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/* -> starting from the end of the syllable, move backwards */
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i = end;
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do {
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i--;
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/* -> until a consonant is found */
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if (buffer->info[i].indic_category() == OT_C)
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{
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/* -> that does not have a below-base or post-base form
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* (post-base forms have to follow below-base forms), */
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if (buffer->info[i].indic_position() != POS_BELOW &&
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buffer->info[i].indic_position() != POS_POST)
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{
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base = i;
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break;
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}
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find_syllables (map, buffer);
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/* TODO: or that is not a pre-base reordering Ra, */
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/* -> or arrive at the first consonant. The consonant stopped at will be the base. */
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base = i;
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}
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} while (i > start);
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if (base < start)
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base = start; /* Just in case... */
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/* TODO
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* If the syllable starts with Ra + Halant (in a script that has Reph)
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* and has more than one consonant, Ra is excluded from candidates for
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* base consonants. */
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/* 2. Decompose and reorder Matras:
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*
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* Each matra and any syllable modifier sign in the cluster are moved to the
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* appropriate position relative to the consonant(s) in the cluster. The
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* shaping engine decomposes two- or three-part matras into their constituent
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* parts before any repositioning. Matra characters are classified by which
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* consonant in a conjunct they have affinity for and are reordered to the
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* following positions:
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*
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* o Before first half form in the syllable
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* o After subjoined consonants
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* o After post-form consonant
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* o After main consonant (for above marks)
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*
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* IMPLEMENTATION NOTES:
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*
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* The normalize() routine has already decomposed matras for us, so we don't
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* need to worry about that.
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*/
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/* 3. Reorder marks to canonical order:
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*
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* Adjacent nukta and halant or nukta and vedic sign are always repositioned
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* if necessary, so that the nukta is first.
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*
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* IMPLEMENTATION NOTES:
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*
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* We don't need to do this: the normalize() routine already did this for us.
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*/
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/* Setup masks now */
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/* Pre-base */
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for (i = start; i < base; i++)
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buffer->info[i].mask |= mask_array[HALF] | mask_array[AKHN];
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/* Base */
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buffer->info[base].mask |= mask_array[AKHN];
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/* Post-base */
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for (i = base + 1; i < end; i++)
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buffer->info[i].mask |= mask_array[BLWF] | mask_array[PSTF];
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}
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static void
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found_vowel_syllable (const hb_ot_map_t *map, hb_buffer_t *buffer, hb_mask_t *mask_array,
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unsigned int start, unsigned int end)
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{
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/* TODO
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* Not clear to me how this should work. Do the matras move to before the
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* independent vowel? No idea.
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*/
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}
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static void
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found_standalone_cluster (const hb_ot_map_t *map, hb_buffer_t *buffer, hb_mask_t *mask_array,
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unsigned int start, unsigned int end)
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{
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/* TODO
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* Easiest thing to do here is to convert the NBSP to consonant and
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* call found_consonant_syllable.
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*/
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}
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static void
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found_non_indic (const hb_ot_map_t *map, hb_buffer_t *buffer, hb_mask_t *mask_array,
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unsigned int start, unsigned int end)
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{
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/* Nothing to do right now. If we ever switch to using the output
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* buffer in the reordering process, we'd need to next_glyph() here. */
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}
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#include "hb-ot-shape-complex-indic-machine.hh"
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static void
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initial_reordering (const hb_ot_map_t *map,
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hb_face_t *face,
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hb_buffer_t *buffer,
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void *user_data HB_UNUSED)
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{
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hb_mask_t mask_array[ARRAY_LENGTH (indic_basic_features)] = {0};
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unsigned int num_masks = ARRAY_LENGTH (indic_basic_features);
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for (unsigned int i = 0; i < num_masks; i++)
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mask_array[i] = map->get_1_mask (indic_basic_features[i].tag);
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find_syllables (map, buffer, mask_array);
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}
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static void
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final_reordering (const hb_ot_map_t *map,
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hb_face_t *face,
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hb_buffer_t *buffer,
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void *user_data HB_UNUSED)
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{
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HB_BUFFER_DEALLOCATE_VAR (buffer, indic_category);
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HB_BUFFER_DEALLOCATE_VAR (buffer, indic_position);
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}
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HB_END_DECLS
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