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libfontmanager /
harfbuzz /
hb-ot-shape-complex-indic.cc
/*
* Copyright © 2011,2012 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
*/
#include "hb-ot-shape-complex-indic.hh"
#include "hb-ot-shape-complex-vowel-constraints.hh"
#include "hb-ot-layout.hh"
/*
* Indic shaper.
*/
/*
* Indic configurations. Note that we do not want to keep every single script-specific
* behavior in these tables necessarily. This should mainly be used for per-script
* properties that are cheaper keeping here, than in the code. Ie. if, say, one and
* only one script has an exception, that one script can be if'ed directly in the code,
* instead of adding a new flag in these structs.
*/
enum base_position_t {
BASE_POS_LAST_SINHALA,
BASE_POS_LAST
};
enum reph_position_t {
REPH_POS_AFTER_MAIN = POS_AFTER_MAIN,
REPH_POS_BEFORE_SUB = POS_BEFORE_SUB,
REPH_POS_AFTER_SUB = POS_AFTER_SUB,
REPH_POS_BEFORE_POST = POS_BEFORE_POST,
REPH_POS_AFTER_POST = POS_AFTER_POST
};
enum reph_mode_t {
REPH_MODE_IMPLICIT, /* Reph formed out of initial Ra,H sequence. */
REPH_MODE_EXPLICIT, /* Reph formed out of initial Ra,H,ZWJ sequence. */
REPH_MODE_LOG_REPHA /* Encoded Repha character, needs reordering. */
};
enum blwf_mode_t {
BLWF_MODE_PRE_AND_POST, /* Below-forms feature applied to pre-base and post-base. */
BLWF_MODE_POST_ONLY /* Below-forms feature applied to post-base only. */
};
struct indic_config_t
{
hb_script_t script;
bool has_old_spec;
hb_codepoint_t virama;
base_position_t base_pos;
reph_position_t reph_pos;
reph_mode_t reph_mode;
blwf_mode_t blwf_mode;
};
static const indic_config_t indic_configs[] =
{
/* Default. Should be first. */
{HB_SCRIPT_INVALID, false, 0,BASE_POS_LAST, REPH_POS_BEFORE_POST,REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
{HB_SCRIPT_DEVANAGARI,true, 0x094Du,BASE_POS_LAST, REPH_POS_BEFORE_POST,REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
{HB_SCRIPT_BENGALI, true, 0x09CDu,BASE_POS_LAST, REPH_POS_AFTER_SUB, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
{HB_SCRIPT_GURMUKHI, true, 0x0A4Du,BASE_POS_LAST, REPH_POS_BEFORE_SUB, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
{HB_SCRIPT_GUJARATI, true, 0x0ACDu,BASE_POS_LAST, REPH_POS_BEFORE_POST,REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
{HB_SCRIPT_ORIYA, true, 0x0B4Du,BASE_POS_LAST, REPH_POS_AFTER_MAIN, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
{HB_SCRIPT_TAMIL, true, 0x0BCDu,BASE_POS_LAST, REPH_POS_AFTER_POST, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST},
{HB_SCRIPT_TELUGU, true, 0x0C4Du,BASE_POS_LAST, REPH_POS_AFTER_POST, REPH_MODE_EXPLICIT, BLWF_MODE_POST_ONLY},
{HB_SCRIPT_KANNADA, true, 0x0CCDu,BASE_POS_LAST, REPH_POS_AFTER_POST, REPH_MODE_IMPLICIT, BLWF_MODE_POST_ONLY},
{HB_SCRIPT_MALAYALAM, true, 0x0D4Du,BASE_POS_LAST, REPH_POS_AFTER_MAIN, REPH_MODE_LOG_REPHA,BLWF_MODE_PRE_AND_POST},
{HB_SCRIPT_SINHALA, false,0x0DCAu,BASE_POS_LAST_SINHALA,
REPH_POS_AFTER_POST, REPH_MODE_EXPLICIT, BLWF_MODE_PRE_AND_POST},
};
/*
* Indic shaper.
*/
static const hb_ot_map_feature_t
indic_features[] =
{
/*
* Basic features.
* These features are applied in order, one at a time, after initial_reordering.
*/
{HB_TAG('n','u','k','t'), F_GLOBAL_MANUAL_JOINERS},
{HB_TAG('a','k','h','n'), F_GLOBAL_MANUAL_JOINERS},
{HB_TAG('r','p','h','f'), F_MANUAL_JOINERS},
{HB_TAG('r','k','r','f'), F_GLOBAL_MANUAL_JOINERS},
{HB_TAG('p','r','e','f'), F_MANUAL_JOINERS},
{HB_TAG('b','l','w','f'), F_MANUAL_JOINERS},
{HB_TAG('a','b','v','f'), F_MANUAL_JOINERS},
{HB_TAG('h','a','l','f'), F_MANUAL_JOINERS},
{HB_TAG('p','s','t','f'), F_MANUAL_JOINERS},
{HB_TAG('v','a','t','u'), F_GLOBAL_MANUAL_JOINERS},
{HB_TAG('c','j','c','t'), F_GLOBAL_MANUAL_JOINERS},
/*
* Other features.
* These features are applied all at once, after final_reordering
* but before clearing syllables.
* Default Bengali font in Windows for example has intermixed
* lookups for init,pres,abvs,blws features.
*/
{HB_TAG('i','n','i','t'), F_MANUAL_JOINERS},
{HB_TAG('p','r','e','s'), F_GLOBAL_MANUAL_JOINERS},
{HB_TAG('a','b','v','s'), F_GLOBAL_MANUAL_JOINERS},
{HB_TAG('b','l','w','s'), F_GLOBAL_MANUAL_JOINERS},
{HB_TAG('p','s','t','s'), F_GLOBAL_MANUAL_JOINERS},
{HB_TAG('h','a','l','n'), F_GLOBAL_MANUAL_JOINERS},
/*
* Positioning features.
* We don't care about the types.
*/
{HB_TAG('d','i','s','t'), F_GLOBAL},
{HB_TAG('a','b','v','m'), F_GLOBAL},
{HB_TAG('b','l','w','m'), F_GLOBAL},
};
/*
* Must be in the same order as the indic_features array.
*/
enum {
_NUKT,
_AKHN,
RPHF,
_RKRF,
PREF,
BLWF,
ABVF,
HALF,
PSTF,
_VATU,
_CJCT,
INIT,
_PRES,
_ABVS,
_BLWS,
_PSTS,
_HALN,
_DIST,
_ABVM,
_BLWM,
INDIC_NUM_FEATURES,
INDIC_BASIC_FEATURES = INIT, /* 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
clear_syllables (const hb_ot_shape_plan_t *plan,
hb_font_t *font,
hb_buffer_t *buffer);
static void
collect_features_indic (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->enable_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->enable_feature (HB_TAG('c','c','m','p'));
unsigned int i = 0;
map->add_gsub_pause (initial_reordering);
for (; i < INDIC_BASIC_FEATURES; i++) {
map->add_feature (indic_features[i]);
map->add_gsub_pause (nullptr);
}
map->add_gsub_pause (final_reordering);
for (; i < INDIC_NUM_FEATURES; i++)
map->add_feature (indic_features[i]);
map->enable_feature (HB_TAG('c','a','l','t'));
map->enable_feature (HB_TAG('c','l','i','g'));
map->add_gsub_pause (clear_syllables);
}
static void
override_features_indic (hb_ot_shape_planner_t *plan)
{
plan->map.disable_feature (HB_TAG('l','i','g','a'));
}
struct 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_fast (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;
};
struct indic_shape_plan_t
{
bool load_virama_glyph (hb_font_t *font, hb_codepoint_t *pglyph) const
{
hb_codepoint_t glyph = virama_glyph.get_relaxed ();
if (unlikely (glyph == (hb_codepoint_t) -1))
{
if (!config->virama || !font->get_nominal_glyph (config->virama, &glyph))
glyph = 0;
/* Technically speaking, the spec says we should apply 'locl' to virama too.
* Maybe one day... */
/* Our get_nominal_glyph() function needs a font, so we can't get the virama glyph
* during shape planning... Instead, overwrite it here. */
virama_glyph.set_relaxed ((int) glyph);
}
*pglyph = glyph;
return glyph != 0;
}
const indic_config_t *config;
bool is_old_spec;
bool uniscribe_bug_compatible;
mutable hb_atomic_int_t virama_glyph;
would_substitute_feature_t rphf;
would_substitute_feature_t pref;
would_substitute_feature_t blwf;
would_substitute_feature_t pstf;
hb_mask_t mask_array[INDIC_NUM_FEATURES];
};
static void *
data_create_indic (const hb_ot_shape_plan_t *plan)
{
indic_shape_plan_t *indic_plan = (indic_shape_plan_t *) calloc (1, sizeof (indic_shape_plan_t));
if (unlikely (!indic_plan))
return nullptr;
indic_plan->config = &indic_configs[0];
for (unsigned int i = 1; i < ARRAY_LENGTH (indic_configs); i++)
if (plan->props.script == indic_configs[i].script) {
indic_plan->config = &indic_configs[i];
break;
}
indic_plan->is_old_spec = indic_plan->config->has_old_spec && ((plan->map.chosen_script[0] & 0x000000FFu) != '2');
indic_plan->uniscribe_bug_compatible = hb_options ().uniscribe_bug_compatible;
indic_plan->virama_glyph.set_relaxed (-1);
/* Use zero-context would_substitute() matching for new-spec of the main
* Indic scripts, and scripts with one spec only, but not for old-specs.
* The new-spec for all dual-spec scripts says zero-context matching happens.
*
* However, testing with Malayalam shows that old and new spec both allow
* context. Testing with Bengali new-spec however shows that it doesn't.
* So, the heuristic here is the way it is. It should *only* be changed,
* as we discover more cases of what Windows does. DON'T TOUCH OTHERWISE.
*/
bool zero_context = !indic_plan->is_old_spec && plan->props.script != HB_SCRIPT_MALAYALAM;
indic_plan->rphf.init (&plan->map, HB_TAG('r','p','h','f'), zero_context);
indic_plan->pref.init (&plan->map, HB_TAG('p','r','e','f'), zero_context);
indic_plan->blwf.init (&plan->map, HB_TAG('b','l','w','f'), zero_context);
indic_plan->pstf.init (&plan->map, HB_TAG('p','s','t','f'), zero_context);
for (unsigned int i = 0; i < ARRAY_LENGTH (indic_plan->mask_array); i++)
indic_plan->mask_array[i] = (indic_features[i].flags & F_GLOBAL) ?
0 : plan->map.get_1_mask (indic_features[i].tag);
return indic_plan;
}
static void
data_destroy_indic (void *data)
{
free (data);
}
static indic_position_t
consonant_position_from_face (const indic_shape_plan_t *indic_plan,
const hb_codepoint_t consonant,
const hb_codepoint_t virama,
hb_face_t *face)
{
/* For old-spec, the order of glyphs is Consonant,Virama,
* whereas for new-spec, it's Virama,Consonant. However,
* some broken fonts (like Free Sans) simply copied lookups
* from old-spec to new-spec without modification.
* And oddly enough, Uniscribe seems to respect those lookups.
* Eg. in the sequence U+0924,U+094D,U+0930, Uniscribe finds
* base at 0. The font however, only has lookups matching
* 930,94D in 'blwf', not the expected 94D,930 (with new-spec
* table). As such, we simply match both sequences. Seems
* to work. */
hb_codepoint_t glyphs[3] = {virama, consonant, virama};
if (indic_plan->blwf.would_substitute (glyphs , 2, face) ||
indic_plan->blwf.would_substitute (glyphs+1, 2, face))
return POS_BELOW_C;
if (indic_plan->pstf.would_substitute (glyphs , 2, face) ||
indic_plan->pstf.would_substitute (glyphs+1, 2, face))
return POS_POST_C;
if (indic_plan->pref.would_substitute (glyphs , 2, face) ||
indic_plan->pref.would_substitute (glyphs+1, 2, face))
return POS_POST_C;
return POS_BASE_C;
}
enum syllable_type_t {
consonant_syllable,
vowel_syllable,
standalone_cluster,
symbol_cluster,
broken_cluster,
non_indic_cluster,
};
#include "hb-ot-shape-complex-indic-machine.hh"
static void
setup_masks_indic (const hb_ot_shape_plan_t *plan HB_UNUSED,
hb_buffer_t *buffer,
hb_font_t *font HB_UNUSED)
{
HB_BUFFER_ALLOCATE_VAR (buffer, indic_category);
HB_BUFFER_ALLOCATE_VAR (buffer, indic_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;
hb_glyph_info_t *info = buffer->info;
for (unsigned int i = 0; i < count; i++)
set_indic_properties (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);
foreach_syllable (buffer, start, end)
buffer->unsafe_to_break (start, end);
}
static int
compare_indic_order (const hb_glyph_info_t *pa, const hb_glyph_info_t *pb)
{
int a = pa->indic_position();
int b = pb->indic_position();
return a < b ? -1 : a == b ? 0 : +1;
}
static void
update_consonant_positions (const hb_ot_shape_plan_t *plan,
hb_font_t *font,
hb_buffer_t *buffer)
{
const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data;
if (indic_plan->config->base_pos != BASE_POS_LAST)
return;
hb_codepoint_t virama;
if (indic_plan->load_virama_glyph (font, &virama))
{
hb_face_t *face = font->face;
unsigned int count = buffer->len;
hb_glyph_info_t *info = buffer->info;
for (unsigned int i = 0; i < count; i++)
if (info[i].indic_position() == POS_BASE_C)
{
hb_codepoint_t consonant = info[i].codepoint;
info[i].indic_position() = consonant_position_from_face (indic_plan, consonant, virama, face);
}
}
}
/* Rules from:
* https://docs.microsqoft.com/en-us/typography/script-development/devanagari */
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)
{
const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data;
hb_glyph_info_t *info = buffer->info;
/* https://github.com/harfbuzz/harfbuzz/issues/435#issuecomment-335560167
* // For compatibility with legacy usage in Kannada,
* // Ra+h+ZWJ must behave like Ra+ZWJ+h...
*/
if (buffer->props.script == HB_SCRIPT_KANNADA &&
start + 3 <= end &&
is_one_of (info[start ], FLAG (OT_Ra)) &&
is_one_of (info[start+1], FLAG (OT_H)) &&
is_one_of (info[start+2], FLAG (OT_ZWJ)))
{
buffer->merge_clusters (start+1, start+3);
hb_glyph_info_t tmp = info[start+1];
info[start+1] = info[start+2];
info[start+2] = tmp;
}
/* 1. Find base consonant:
*
* The shaping engine finds the base consonant of the syllable, using the
* following algorithm: starting from the end of the syllable, move backwards
* until a consonant is found that does not have a below-base or post-base
* form (post-base forms have to follow below-base forms), or that is not a
* pre-base-reordering Ra, or arrive at the first consonant. The consonant
* stopped at will be the base.
*
* o If the syllable starts with Ra + Halant (in a script that has Reph)
* and has more than one consonant, Ra is excluded from candidates for
* base consonants.
*/
unsigned int base = end;
bool has_reph = false;
{
/* -> If the syllable starts with Ra + Halant (in a script that has Reph)
* and has more than one consonant, Ra is excluded from candidates for
* base consonants. */
unsigned int limit = start;
if (indic_plan->mask_array[RPHF] &&
start + 3 <= end &&
(
(indic_plan->config->reph_mode == REPH_MODE_IMPLICIT && !is_joiner (info[start + 2])) ||
(indic_plan->config->reph_mode == REPH_MODE_EXPLICIT && info[start + 2].indic_category() == OT_ZWJ)
))
{
/* See if it matches the 'rphf' feature. */
hb_codepoint_t glyphs[3] = {info[start].codepoint,
info[start + 1].codepoint,
indic_plan->config->reph_mode == REPH_MODE_EXPLICIT ?
info[start + 2].codepoint : 0};
if (indic_plan->rphf.would_substitute (glyphs, 2, face) ||
(indic_plan->config->reph_mode == REPH_MODE_EXPLICIT &&
indic_plan->rphf.would_substitute (glyphs, 3, face)))
{
limit += 2;
while (limit < end && is_joiner (info[limit]))
limit++;
base = start;
has_reph = true;
}
} else if (indic_plan->config->reph_mode == REPH_MODE_LOG_REPHA && info[start].indic_category() == OT_Repha)
{
limit += 1;
while (limit < end && is_joiner (info[limit]))
limit++;
base = start;
has_reph = true;
}
switch (indic_plan->config->base_pos)
{
case BASE_POS_LAST:
{
/* -> starting from the end of the syllable, move backwards */
unsigned int i = end;
bool seen_below = false;
do {
i--;
/* -> until a consonant is found */
if (is_consonant (info[i]))
{
/* -> that does not have a below-base or post-base form
* (post-base forms have to follow below-base forms), */
if (info[i].indic_position() != POS_BELOW_C &&
(info[i].indic_position() != POS_POST_C || seen_below))
{
base = i;
break;
}
if (info[i].indic_position() == POS_BELOW_C)
seen_below = true;
/* -> or that is not a pre-base-reordering Ra,
*
* IMPLEMENTATION NOTES:
*
* Our pre-base-reordering Ra's are marked POS_POST_C, so will be skipped
* by the logic above already.
*/
/* -> or arrive at the first consonant. The consonant stopped at will
* be the base. */
base = i;
}
else
{
/* A ZWJ after a Halant stops the base search, and requests an explicit
* half form.
* A ZWJ before a Halant, requests a subjoined form instead, and hence
* search continues. This is particularly important for Bengali
* sequence Ra,H,Ya that should form Ya-Phalaa by subjoining Ya. */
if (start < i &&
info[i].indic_category() == OT_ZWJ &&
info[i - 1].indic_category() == OT_H)
break;
}
} while (i > limit);
}
break;
case BASE_POS_LAST_SINHALA:
{
/* Sinhala base positioning is slightly different from main Indic, in that:
* 1. Its ZWJ behavior is different,
* 2. We don't need to look into the font for consonant positions.
*/
if (!has_reph)
base = limit;
/* Find the last base consonant that is not blocked by ZWJ. If there is
* a ZWJ right before a base consonant, that would request a subjoined form. */
for (unsigned int i = limit; i < end; i++)
if (is_consonant (info[i]))
{
if (limit < i && info[i - 1].indic_category() == OT_ZWJ)
break;
else
base = i;
}
/* Mark all subsequent consonants as below. */
for (unsigned int i = base + 1; i < end; i++)
if (is_consonant (info[i]))
info[i].indic_position() = POS_BELOW_C;
}
break;
}
/* -> If the syllable starts with Ra + Halant (in a script that has Reph)
* and has more than one consonant, Ra is excluded from candidates for
* base consonants.
*
* Only do this for unforced Reph. (ie. not for Ra,H,ZWJ. */
if (has_reph && base == start && limit - base <= 2) {
/* Have no other consonant, so Reph is not formed and Ra becomes base. */
has_reph = false;
}
}
/* 2. Decompose and reorder Matras:
*
* Each matra and any syllable modifier sign in the syllable are moved to the
* appropriate position relative to the consonant(s) in the syllable. The
* shaping engine decomposes two- or three-part matras into their constituent
* parts before any repositioning. Matra characters are classified by which
* consonant in a conjunct they have affinity for and are reordered to the
* following positions:
*
* o Before first half form in the syllable
* o After subjoined consonants
* o After post-form consonant
* o After main consonant (for above marks)
*
* IMPLEMENTATION NOTES:
*
* The normalize() routine has already decomposed matras for us, so we don't
* need to worry about that.
*/
/* 3. Reorder marks to canonical order:
*
* Adjacent nukta and halant or nukta and vedic sign are always repositioned
* if necessary, so that the nukta is first.
*
* IMPLEMENTATION NOTES:
*
* We don't need to do this: the normalize() routine already did this for us.
*/
/* Reorder characters */
for (unsigned int i = start; i < base; i++)
info[i].indic_position() = MIN (POS_PRE_C, (indic_position_t) info[i].indic_position());
if (base < end)
info[base].indic_position() = POS_BASE_C;
/* Mark final consonants. A final consonant is one appearing after a matra.
* Happens in Sinhala. */
for (unsigned int i = base + 1; i < end; i++)
if (info[i].indic_category() == OT_M) {
for (unsigned int j = i + 1; j < end; j++)
if (is_consonant (info[j])) {
info[j].indic_position() = POS_FINAL_C;
break;
}
break;
}
/* Handle beginning Ra */
if (has_reph)
info[start].indic_position() = POS_RA_TO_BECOME_REPH;
/* For old-style Indic script tags, move the first post-base Halant after
* last consonant.
*
* Reports suggest that in some scripts Uniscribe does this only if there
* is *not* a Halant after last consonant already. We know that is the
* case for Kannada, while it reorders unconditionally in other scripts,
* eg. Malayalam, Bengali, and Devanagari. We don't currently know about
* other scripts, so we blacklist Kannada.
*
* Kannada test case:
* U+0C9A,U+0CCD,U+0C9A,U+0CCD
* With some versions of Lohit Kannada.
* https://bugs.freedesktop.org/show_bug.cgi?id=59118
*
* Malayalam test case:
* U+0D38,U+0D4D,U+0D31,U+0D4D,U+0D31,U+0D4D
* With lohit-ttf-20121122/Lohit-Malayalam.ttf
*
* Bengali test case:
* U+0998,U+09CD,U+09AF,U+09CD
* With Windows XP vrinda.ttf
* https://github.com/harfbuzz/harfbuzz/issues/1073
*
* Devanagari test case:
* U+091F,U+094D,U+0930,U+094D
* With chandas.ttf
* https://github.com/harfbuzz/harfbuzz/issues/1071
*/
if (indic_plan->is_old_spec)
{
bool disallow_double_halants = buffer->props.script == HB_SCRIPT_KANNADA;
for (unsigned int i = base + 1; i < end; i++)
if (info[i].indic_category() == OT_H)
{
unsigned int j;
for (j = end - 1; j > i; j--)
if (is_consonant (info[j]) ||
(disallow_double_halants && info[j].indic_category() == OT_H))
break;
if (info[j].indic_category() != OT_H && j > i) {
/* Move Halant to after last consonant. */
hb_glyph_info_t t = info[i];
memmove (&info[i], &info[i + 1], (j - i) * sizeof (info[0]));
info[j] = t;
}
break;
}
}
/* Attach misc marks to previous char to move with them. */
{
indic_position_t last_pos = POS_START;
for (unsigned int i = start; i < end; i++)
{
if ((FLAG_UNSAFE (info[i].indic_category()) & (JOINER_FLAGS | FLAG (OT_N) | FLAG (OT_RS) | FLAG (OT_H))))
{
info[i].indic_position() = last_pos;
if (unlikely (info[i].indic_category() == OT_H &&
info[i].indic_position() == POS_PRE_M))
{
/*
* Uniscribe doesn't move the Halant with Left Matra.
* TEST: U+092B,U+093F,U+094DE
* We follow. This is important for the Sinhala
* U+0DDA split matra since it decomposes to U+0DD9,U+0DCA
* where U+0DD9 is a left matra and U+0DCA is the virama.
* We don't want to move the virama with the left matra.
* TEST: U+0D9A,U+0DDA
*/
for (unsigned int j = i; j > start; j--)
if (info[j - 1].indic_position() != POS_PRE_M) {
info[i].indic_position() = info[j - 1].indic_position();
break;
}
}
} else if (info[i].indic_position() != POS_SMVD) {
last_pos = (indic_position_t) info[i].indic_position();
}
}
}
/* For post-base consonants let them own anything before them
* since the last consonant or matra. */
{
unsigned int last = base;
for (unsigned int i = base + 1; i < end; i++)
if (is_consonant (info[i]))
{
for (unsigned int j = last + 1; j < i; j++)
if (info[j].indic_position() < POS_SMVD)
info[j].indic_position() = info[i].indic_position();
last = i;
} else if (info[i].indic_category() == OT_M)
last = i;
}
{
/* Use syllable() for sort accounting temporarily. */
unsigned int syllable = info[start].syllable();
for (unsigned int i = start; i < end; i++)
info[i].syllable() = i - start;
/* Sit tight, rock 'n roll! */
hb_stable_sort (info + start, end - start, compare_indic_order);
/* Find base again */
base = end;
for (unsigned int i = start; i < end; i++)
if (info[i].indic_position() == POS_BASE_C)
{
base = i;
break;
}
/* Things are out-of-control for post base positions, they may shuffle
* around like crazy. In old-spec mode, we move halants around, so in
* that case merge all clusters after base. Otherwise, check the sort
* order and merge as needed.
* For pre-base stuff, we handle cluster issues in final reordering.
*
* We could use buffer->sort() for this, if there was no special
* reordering of pre-base stuff happening later...
* We don't want to merge_clusters all of that, which buffer->sort()
* would.
*/
if (indic_plan->is_old_spec || end - start > 127)
buffer->merge_clusters (base, end);
else
{
/* Note! syllable() is a one-byte field. */
for (unsigned int i = base; i < end; i++)
if (info[i].syllable() != 255)
{
unsigned int max = i;
unsigned int j = start + info[i].syllable();
while (j != i)
{
max = MAX (max, j);
unsigned int next = start + info[j].syllable();
info[j].syllable() = 255; /* So we don't process j later again. */
j = next;
}
if (i != max)
buffer->merge_clusters (i, max + 1);
}
}
/* Put syllable back in. */
for (unsigned int i = start; i < end; i++)
info[i].syllable() = syllable;
}
/* Setup masks now */
{
hb_mask_t mask;
/* Reph */
for (unsigned int i = start; i < end && info[i].indic_position() == POS_RA_TO_BECOME_REPH; i++)
info[i].mask |= indic_plan->mask_array[RPHF];
/* Pre-base */
mask = indic_plan->mask_array[HALF];
if (!indic_plan->is_old_spec &&
indic_plan->config->blwf_mode == BLWF_MODE_PRE_AND_POST)
mask |= indic_plan->mask_array[BLWF];
for (unsigned int i = start; i < base; i++)
info[i].mask |= mask;
/* Base */
mask = 0;
if (base < end)
info[base].mask |= mask;
/* Post-base */
mask = indic_plan->mask_array[BLWF] | indic_plan->mask_array[ABVF] | indic_plan->mask_array[PSTF];
for (unsigned int i = base + 1; i < end; i++)
info[i].mask |= mask;
}
if (indic_plan->is_old_spec &&
buffer->props.script == HB_SCRIPT_DEVANAGARI)
{
/* Old-spec eye-lash Ra needs special handling. From the
* spec:
*
* "The feature 'below-base form' is applied to consonants
* having below-base forms and following the base consonant.
* The exception is vattu, which may appear below half forms
* as well as below the base glyph. The feature 'below-base
* form' will be applied to all such occurrences of Ra as well."
*
* Test case: U+0924,U+094D,U+0930,U+094d,U+0915
* with Sanskrit 2003 font.
*
* However, note that Ra,Halant,ZWJ is the correct way to
* request eyelash form of Ra, so we wouldbn't inhibit it
* in that sequence.
*
* Test case: U+0924,U+094D,U+0930,U+094d,U+200D,U+0915
*/
for (unsigned int i = start; i + 1 < base; i++)
if (info[i ].indic_category() == OT_Ra &&
info[i+1].indic_category() == OT_H &&
(i + 2 == base ||
info[i+2].indic_category() != OT_ZWJ))
{
info[i ].mask |= indic_plan->mask_array[BLWF];
info[i+1].mask |= indic_plan->mask_array[BLWF];
}
}
unsigned int pref_len = 2;
if (indic_plan->mask_array[PREF] && base + pref_len < end)
{
/* Find a Halant,Ra sequence and mark it for pre-base-reordering processing. */
for (unsigned int i = base + 1; i + pref_len - 1 < end; i++) {
hb_codepoint_t glyphs[2];
for (unsigned int j = 0; j < pref_len; j++)
glyphs[j] = info[i + j].codepoint;
if (indic_plan->pref.would_substitute (glyphs, pref_len, face))
{
for (unsigned int j = 0; j < pref_len; j++)
info[i++].mask |= indic_plan->mask_array[PREF];
break;
}
}
}
/* Apply ZWJ/ZWNJ effects */
for (unsigned int i = start + 1; i < end; i++)
if (is_joiner (info[i])) {
bool non_joiner = info[i].indic_category() == OT_ZWNJ;
unsigned int j = i;
do {
j--;
/* ZWJ/ZWNJ should disable CJCT. They do that by simply
* being there, since we don't skip them for the CJCT
* feature (ie. F_MANUAL_ZWJ) */
/* A ZWNJ disables HALF. */
if (non_joiner)
info[j].mask &= ~indic_plan->mask_array[HALF];
} while (j > start && !is_consonant (info[j]));
}
}
static void
initial_reordering_standalone_cluster (const hb_ot_shape_plan_t *plan,
hb_face_t *face,
hb_buffer_t *buffer,
unsigned int start, unsigned int end)
{
const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data;
/* We treat placeholder/dotted-circle as if they are consonants, so we
* should just chain. Only if not in compatibility mode that is... */
if (indic_plan->uniscribe_bug_compatible)
{
/* For dotted-circle, this is what Uniscribe does:
* If dotted-circle is the last glyph, it just does nothing.
* Ie. It doesn't form Reph. */
if (buffer->info[end - 1].indic_category() == OT_DOTTEDCIRCLE)
return;
}
initial_reordering_consonant_syllable (plan, face, buffer, start, end);
}
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 vowel_syllable: /* We made the vowels look like consonants. So let's call the consonant logic! */
case consonant_syllable:
initial_reordering_consonant_syllable (plan, face, buffer, start, end);
break;
case broken_cluster: /* We already inserted dotted-circles, so just call the standalone_cluster. */
case standalone_cluster:
initial_reordering_standalone_cluster (plan, face, buffer, start, end);
break;
case symbol_cluster:
case non_indic_cluster:
break;
}
}
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.
* TODO Use a buffer scratch flag to remove the loop. */
bool has_broken_syllables = false;
unsigned int count = buffer->len;
hb_glyph_info_t *info = buffer->info;
for (unsigned int i = 0; i < count; i++)
if ((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_nominal_glyph (0x25CCu, &dottedcircle_glyph))
return;
hb_glyph_info_t dottedcircle = {0};
dottedcircle.codepoint = 0x25CCu;
set_indic_properties (dottedcircle);
dottedcircle.codepoint = dottedcircle_glyph;
buffer->clear_output ();
buffer->idx = 0;
unsigned int last_syllable = 0;
while (buffer->idx < buffer->len && buffer->successful)
{
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 ginfo = dottedcircle;
ginfo.cluster = buffer->cur().cluster;
ginfo.mask = buffer->cur().mask;
ginfo.syllable() = buffer->cur().syllable();
/* TODO Set glyph_props? */
/* Insert dottedcircle after possible Repha. */
while (buffer->idx < buffer->len && buffer->successful &&
last_syllable == buffer->cur().syllable() &&
buffer->cur().indic_category() == OT_Repha)
buffer->next_glyph ();
buffer->output_info (ginfo);
}
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)
{
update_consonant_positions (plan, font, buffer);
insert_dotted_circles (plan, font, buffer);
foreach_syllable (buffer, start, end)
initial_reordering_syllable (plan, font->face, buffer, start, end);
}
static void
final_reordering_syllable (const hb_ot_shape_plan_t *plan,
hb_buffer_t *buffer,
unsigned int start, unsigned int end)
{
const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data;
hb_glyph_info_t *info = buffer->info;
/* This function relies heavily on halant glyphs. Lots of ligation
* and possibly multiple substitutions happened prior to this
* phase, and that might have messed up our properties. Recover
* from a particular case of that where we're fairly sure that a
* class of OT_H is desired but has been lost. */
/* We don't call load_virama_glyph(), since we know it's already
* loaded. */
hb_codepoint_t virama_glyph = indic_plan->virama_glyph.get_relaxed ();
if (virama_glyph)
{
for (unsigned int i = start; i < end; i++)
if (info[i].codepoint == virama_glyph &&
_hb_glyph_info_ligated (&info[i]) &&
_hb_glyph_info_multiplied (&info[i]))
{
/* This will make sure that this glyph passes is_halant() test. */
info[i].indic_category() = OT_H;
_hb_glyph_info_clear_ligated_and_multiplied (&info[i]);
}
}
/* 4. Final reordering:
*
* After the localized forms and basic shaping forms GSUB features have been
* applied (see below), the shaping engine performs some final glyph
* reordering before applying all the remaining font features to the entire
* syllable.
*/
bool try_pref = !!indic_plan->mask_array[PREF];
/* Find base again */
unsigned int base;
for (base = start; base < end; base++)
if (info[base].indic_position() >= POS_BASE_C)
{
if (try_pref && base + 1 < end)
{
for (unsigned int i = base + 1; i < end; i++)
if ((info[i].mask & indic_plan->mask_array[PREF]) != 0)
{
if (!(_hb_glyph_info_substituted (&info[i]) &&
_hb_glyph_info_ligated_and_didnt_multiply (&info[i])))
{
/* Ok, this was a 'pref' candidate but didn't form any.
* Base is around here... */
base = i;
while (base < end && is_halant (info[base]))
base++;
info[base].indic_position() = POS_BASE_C;
try_pref = false;
}
break;
}
}
/* For Malayalam, skip over unformed below- (but NOT post-) forms. */
if (buffer->props.script == HB_SCRIPT_MALAYALAM)
{
for (unsigned int i = base + 1; i < end; i++)
{
while (i < end && is_joiner (info[i]))
i++;
if (i == end || !is_halant (info[i]))
break;
i++; /* Skip halant. */
while (i < end && is_joiner (info[i]))
i++;
if (i < end && is_consonant (info[i]) && info[i].indic_position() == POS_BELOW_C)
{
base = i;
info[base].indic_position() = POS_BASE_C;
}
}
}
if (start < base && info[base].indic_position() > POS_BASE_C)
base--;
break;
}
if (base == end && start < base &&
is_one_of (info[base - 1], FLAG (OT_ZWJ)))
base--;
if (base < end)
while (start < base &&
is_one_of (info[base], (FLAG (OT_N) | FLAG (OT_H))))
base--;
/* o Reorder matras:
*
* If a pre-base matra character had been reordered before applying basic
* features, the glyph can be moved closer to the main consonant based on
* whether half-forms had been formed. Actual position for the matra is
* defined as “after last standalone halant glyph, after initial matra
* position and before the main consonant”. If ZWJ or ZWNJ follow this
* halant, position is moved after it.
*
* IMPLEMENTATION NOTES:
*
* It looks like the last sentence is wrong. Testing, with Windows 7 Uniscribe
* and Devanagari shows that the behavior is best described as:
*
* "If ZWJ follows this halant, matra is NOT repositioned after this halant.
* If ZWNJ follows this halant, position is moved after it."
*
* Test case, with Adobe Devanagari or Nirmala UI:
*
* U+091F,U+094D,U+200C,U+092F,U+093F
* (Matra moves to the middle, after ZWNJ.)
*
* U+091F,U+094D,U+200D,U+092F,U+093F
* (Matra does NOT move, stays to the left.)
*
* https://github.com/harfbuzz/harfbuzz/issues/1070
*/
if (start + 1 < end && start < base) /* Otherwise there can't be any pre-base matra characters. */
{
/* If we lost track of base, alas, position before last thingy. */
unsigned int new_pos = base == end ? base - 2 : base - 1;
/* Malayalam / Tamil do not have "half" forms or explicit virama forms.
* The glyphs formed by 'half' are Chillus or ligated explicit viramas.
* We want to position matra after them.
*/
if (buffer->props.script != HB_SCRIPT_MALAYALAM && buffer->props.script != HB_SCRIPT_TAMIL)
{
search:
while (new_pos > start &&
!(is_one_of (info[new_pos], (FLAG (OT_M) | FLAG (OT_H)))))
new_pos--;
/* If we found no Halant we are done.
* Otherwise only proceed if the Halant does
* not belong to the Matra itself! */
if (is_halant (info[new_pos]) &&
info[new_pos].indic_position() != POS_PRE_M)
{
#if 0 // See comment above
/* -> If ZWJ or ZWNJ follow this halant, position is moved after it. */
if (new_pos + 1 < end && is_joiner (info[new_pos + 1]))
new_pos++;
#endif
if (new_pos + 1 < end)
{
/* -> If ZWJ follows this halant, matra is NOT repositioned after this halant. */
if (info[new_pos + 1].indic_category() == OT_ZWJ)
{
/* Keep searching. */
if (new_pos > start)
{
new_pos--;
goto search;
}
}
/* -> If ZWNJ follows this halant, position is moved after it. */
if (info[new_pos + 1].indic_category() == OT_ZWNJ)
new_pos++;
}
}
else
new_pos = start; /* No move. */
}
if (start < new_pos && info[new_pos].indic_position () != POS_PRE_M)
{
/* Now go see if there's actually any matras... */
for (unsigned int i = new_pos; i > start; i--)
if (info[i - 1].indic_position () == POS_PRE_M)
{
unsigned int old_pos = i - 1;
if (old_pos < base && base <= new_pos) /* Shouldn't actually happen. */
base--;
hb_glyph_info_t tmp = info[old_pos];
memmove (&info[old_pos], &info[old_pos + 1], (new_pos - old_pos) * sizeof (info[0]));
info[new_pos] = tmp;
/* Note: this merge_clusters() is intentionally *after* the reordering.
* Indic matra reordering is special and tricky... */
buffer->merge_clusters (new_pos, MIN (end, base + 1));
new_pos--;
}
} else {
for (unsigned int i = start; i < base; i++)
if (info[i].indic_position () == POS_PRE_M) {
buffer->merge_clusters (i, MIN (end, base + 1));
break;
}
}
}
/* o Reorder reph:
*
* Reph’s original position is always at the beginning of the syllable,
* (i.e. it is not reordered at the character reordering stage). However,
* it will be reordered according to the basic-forms shaping results.
* Possible positions for reph, depending on the script, are; after main,
* before post-base consonant forms, and after post-base consonant forms.
*/
/* Two cases:
*
* - If repha is encoded as a sequence of characters (Ra,H or Ra,H,ZWJ), then
* we should only move it if the sequence ligated to the repha form.
*
* - If repha is encoded separately and in the logical position, we should only
* move it if it did NOT ligate. If it ligated, it's probably the font trying
* to make it work without the reordering.
*/
if (start + 1 < end &&
info[start].indic_position() == POS_RA_TO_BECOME_REPH &&
((info[start].indic_category() == OT_Repha) ^
_hb_glyph_info_ligated_and_didnt_multiply (&info[start])))
{
unsigned int new_reph_pos;
reph_position_t reph_pos = indic_plan->config->reph_pos;
/* 1. If reph should be positioned after post-base consonant forms,
* proceed to step 5.
*/
if (reph_pos == REPH_POS_AFTER_POST)
{
goto reph_step_5;
}
/* 2. If the reph repositioning class is not after post-base: target
* position is after the first explicit halant glyph between the
* first post-reph consonant and last main consonant. If ZWJ or ZWNJ
* are following this halant, position is moved after it. If such
* position is found, this is the target position. Otherwise,
* proceed to the next step.
*
* Note: in old-implementation fonts, where classifications were
* fixed in shaping engine, there was no case where reph position
* will be found on this step.
*/
{
new_reph_pos = start + 1;
while (new_reph_pos < base && !is_halant (info[new_reph_pos]))
new_reph_pos++;
if (new_reph_pos < base && is_halant (info[new_reph_pos]))
{
/* ->If ZWJ or ZWNJ are following this halant, position is moved after it. */
if (new_reph_pos + 1 < base && is_joiner (info[new_reph_pos + 1]))
new_reph_pos++;
goto reph_move;
}
}
/* 3. If reph should be repositioned after the main consonant: find the
* first consonant not ligated with main, or find the first
* consonant that is not a potential pre-base-reordering Ra.
*/
if (reph_pos == REPH_POS_AFTER_MAIN)
{
new_reph_pos = base;
while (new_reph_pos + 1 < end && info[new_reph_pos + 1].indic_position() <= POS_AFTER_MAIN)
new_reph_pos++;
if (new_reph_pos < end)
goto reph_move;
}
/* 4. If reph should be positioned before post-base consonant, find
* first post-base classified consonant not ligated with main. If no
* consonant is found, the target position should be before the
* first matra, syllable modifier sign or vedic sign.
*/
/* This is our take on what step 4 is trying to say (and failing, BADLY). */
if (reph_pos == REPH_POS_AFTER_SUB)
{
new_reph_pos = base;
while (new_reph_pos + 1 < end &&
!( FLAG_UNSAFE (info[new_reph_pos + 1].indic_position()) & (FLAG (POS_POST_C) | FLAG (POS_AFTER_POST) | FLAG (POS_SMVD))))
new_reph_pos++;
if (new_reph_pos < end)
goto reph_move;
}
/* 5. If no consonant is found in steps 3 or 4, move reph to a position
* immediately before the first post-base matra, syllable modifier
* sign or vedic sign that has a reordering class after the intended
* reph position. For example, if the reordering position for reph
* is post-main, it will skip above-base matras that also have a
* post-main position.
*/
reph_step_5:
{
/* Copied from step 2. */
new_reph_pos = start + 1;
while (new_reph_pos < base && !is_halant (info[new_reph_pos]))
new_reph_pos++;
if (new_reph_pos < base && is_halant (info[new_reph_pos]))
{
/* ->If ZWJ or ZWNJ are following this halant, position is moved after it. */
if (new_reph_pos + 1 < base && is_joiner (info[new_reph_pos + 1]))
new_reph_pos++;
goto reph_move;
}
}
/* 6. Otherwise, reorder reph to the end of the syllable.
*/
{
new_reph_pos = end - 1;
while (new_reph_pos > start && info[new_reph_pos].indic_position() == POS_SMVD)
new_reph_pos--;
/*
* If the Reph is to be ending up after a Matra,Halant sequence,
* position it before that Halant so it can interact with the Matra.
* However, if it's a plain Consonant,Halant we shouldn't do that.
* Uniscribe doesn't do this.
* TEST: U+0930,U+094D,U+0915,U+094B,U+094D
*/
if (!indic_plan->uniscribe_bug_compatible &&
unlikely (is_halant (info[new_reph_pos]))) {
for (unsigned int i = base + 1; i < new_reph_pos; i++)
if (info[i].indic_category() == OT_M) {
/* Ok, got it. */
new_reph_pos--;
}
}
goto reph_move;
}
reph_move:
{
/* Move */
buffer->merge_clusters (start, new_reph_pos + 1);
hb_glyph_info_t reph = info[start];
memmove (&info[start], &info[start + 1], (new_reph_pos - start) * sizeof (info[0]));
info[new_reph_pos] = reph;
if (start < base && base <= new_reph_pos)
base--;
}
}
/* o Reorder pre-base-reordering consonants:
*
* If a pre-base-reordering consonant is found, reorder it according to
* the following rules:
*/
if (try_pref && base + 1 < end) /* Otherwise there can't be any pre-base-reordering Ra. */
{
for (unsigned int i = base + 1; i < end; i++)
if ((info[i].mask & indic_plan->mask_array[PREF]) != 0)
{
/* 1. Only reorder a glyph produced by substitution during application
* of the <pref> feature. (Note that a font may shape a Ra consonant with
* the feature generally but block it in certain contexts.)
*/
/* Note: We just check that something got substituted. We don't check that
* the <pref> feature actually did it...
*
* Reorder pref only if it ligated. */
if (_hb_glyph_info_ligated_and_didnt_multiply (&info[i]))
{
/*
* 2. Try to find a target position the same way as for pre-base matra.
* If it is found, reorder pre-base consonant glyph.
*
* 3. If position is not found, reorder immediately before main
* consonant.
*/
unsigned int new_pos = base;
/* Malayalam / Tamil do not have "half" forms or explicit virama forms.
* The glyphs formed by 'half' are Chillus or ligated explicit viramas.
* We want to position matra after them.
*/
if (buffer->props.script != HB_SCRIPT_MALAYALAM && buffer->props.script != HB_SCRIPT_TAMIL)
{
while (new_pos > start &&
!(is_one_of (info[new_pos - 1], FLAG(OT_M) | FLAG (OT_H))))
new_pos--;
}
if (new_pos > start && is_halant (info[new_pos - 1]))
{
/* -> If ZWJ or ZWNJ follow this halant, position is moved after it. */
if (new_pos < end && is_joiner (info[new_pos]))
new_pos++;
}
{
unsigned int old_pos = i;
buffer->merge_clusters (new_pos, old_pos + 1);
hb_glyph_info_t tmp = info[old_pos];
memmove (&info[new_pos + 1], &info[new_pos], (old_pos - new_pos) * sizeof (info[0]));
info[new_pos] = tmp;
if (new_pos <= base && base < old_pos)
base++;
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