/*
* Copyright © 2017 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_AAT_LAYOUT_COMMON_HH
#define HB_AAT_LAYOUT_COMMON_HH
#include "hb-aat-layout.hh"
#include "hb-aat-map.hh"
#include "hb-open-type.hh"
namespace OT {
struct GDEF;
};
namespace AAT {
using namespace OT;
struct ankr;
struct hb_aat_apply_context_t :
hb_dispatch_context_t<hb_aat_apply_context_t, bool, HB_DEBUG_APPLY>
{
const char *get_name () { return "APPLY"; }
template <typename T>
return_t dispatch (const T &obj) { return obj.apply (this); }
static return_t default_return_value () { return false; }
bool stop_sublookup_iteration (return_t r) const { return r; }
const hb_ot_shape_plan_t *plan;
hb_font_t *font;
hb_face_t *face;
hb_buffer_t *buffer;
hb_sanitize_context_t sanitizer;
const ankr *ankr_table;
const OT::GDEF *gdef_table;
const hb_sorted_vector_t<hb_aat_map_t::range_flags_t> *range_flags = nullptr;
hb_mask_t subtable_flags = 0;
/* Unused. For debug tracing only. */
unsigned int lookup_index;
HB_INTERNAL hb_aat_apply_context_t (const hb_ot_shape_plan_t *plan_,
hb_font_t *font_,
hb_buffer_t *buffer_,
hb_blob_t *blob = const_cast<hb_blob_t *> (&Null (hb_blob_t)));
HB_INTERNAL ~hb_aat_apply_context_t ();
HB_INTERNAL void set_ankr_table (const AAT::ankr *ankr_table_);
void set_lookup_index (unsigned int i) { lookup_index = i; }
};
/*
* Lookup Table
*/
template <typename T> struct Lookup;
template <typename T>
struct LookupFormat0
{
friend struct Lookup<T>;
private:
const T* get_value (hb_codepoint_t glyph_id, unsigned int num_glyphs) const
{
if (unlikely (glyph_id >= num_glyphs)) return nullptr;
return &arrayZ[glyph_id];
}
bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (arrayZ.sanitize (c, c->get_num_glyphs ()));
}
bool sanitize (hb_sanitize_context_t *c, const void *base) const
{
TRACE_SANITIZE (this);
return_trace (arrayZ.sanitize (c, c->get_num_glyphs (), base));
}
protected:
HBUINT16 format; /* Format identifier--format = 0 */
UnsizedArrayOf<T>
arrayZ; /* Array of lookup values, indexed by glyph index. */
public:
DEFINE_SIZE_UNBOUNDED (2);
};
template <typename T>
struct LookupSegmentSingle
{
static constexpr unsigned TerminationWordCount = 2u;
int cmp (hb_codepoint_t g) const
{ return g < first ? -1 : g <= last ? 0 : +1 ; }
bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (c->check_struct (this) && value.sanitize (c));
}
bool sanitize (hb_sanitize_context_t *c, const void *base) const
{
TRACE_SANITIZE (this);
return_trace (c->check_struct (this) && value.sanitize (c, base));
}
HBGlyphID16 last; /* Last GlyphID in this segment */
HBGlyphID16 first; /* First GlyphID in this segment */
T value; /* The lookup value (only one) */
public:
DEFINE_SIZE_STATIC (4 + T::static_size);
};
template <typename T>
struct LookupFormat2
{
friend struct Lookup<T>;
private:
const T* get_value (hb_codepoint_t glyph_id) const
{
const LookupSegmentSingle<T> *v = segments.bsearch (glyph_id);
return v ? &v->value : nullptr;
}
bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (segments.sanitize (c));
}
bool sanitize (hb_sanitize_context_t *c, const void *base) const
{
TRACE_SANITIZE (this);
return_trace (segments.sanitize (c, base));
}
protected:
HBUINT16 format; /* Format identifier--format = 2 */
VarSizedBinSearchArrayOf<LookupSegmentSingle<T>>
segments; /* The actual segments. These must already be sorted,
* according to the first word in each one (the last
* glyph in each segment). */
public:
DEFINE_SIZE_ARRAY (8, segments);
};
template <typename T>
struct LookupSegmentArray
{
static constexpr unsigned TerminationWordCount = 2u;
const T* get_value (hb_codepoint_t glyph_id, const void *base) const
{
return first <= glyph_id && glyph_id <= last ? &(base+valuesZ)[glyph_id - first] : nullptr;
}
int cmp (hb_codepoint_t g) const
{ return g < first ? -1 : g <= last ? 0 : +1; }
bool sanitize (hb_sanitize_context_t *c, const void *base) const
{
TRACE_SANITIZE (this);
return_trace (c->check_struct (this) &&
first <= last &&
valuesZ.sanitize (c, base, last - first + 1));
}
template <typename ...Ts>
bool sanitize (hb_sanitize_context_t *c, const void *base, Ts&&... ds) const
{
TRACE_SANITIZE (this);
return_trace (c->check_struct (this) &&
first <= last &&
valuesZ.sanitize (c, base, last - first + 1, std::forward<Ts> (ds)...));
}
HBGlyphID16 last; /* Last GlyphID in this segment */
HBGlyphID16 first; /* First GlyphID in this segment */
NNOffset16To<UnsizedArrayOf<T>>
valuesZ; /* A 16-bit offset from the start of
* the table to the data. */
public:
DEFINE_SIZE_STATIC (6);
};
template <typename T>
struct LookupFormat4
{
friend struct Lookup<T>;
private:
const T* get_value (hb_codepoint_t glyph_id) const
{
const LookupSegmentArray<T> *v = segments.bsearch (glyph_id);
return v ? v->get_value (glyph_id, this) : nullptr;
}
bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (segments.sanitize (c, this));
}
bool sanitize (hb_sanitize_context_t *c, const void *base) const
{
TRACE_SANITIZE (this);
return_trace (segments.sanitize (c, this, base));
}
protected:
HBUINT16 format; /* Format identifier--format = 4 */
VarSizedBinSearchArrayOf<LookupSegmentArray<T>>
segments; /* The actual segments. These must already be sorted,
* according to the first word in each one (the last
* glyph in each segment). */
public:
DEFINE_SIZE_ARRAY (8, segments);
};
template <typename T>
struct LookupSingle
{
static constexpr unsigned TerminationWordCount = 1u;
int cmp (hb_codepoint_t g) const { return glyph.cmp (g); }
bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (c->check_struct (this) && value.sanitize (c));
}
bool sanitize (hb_sanitize_context_t *c, const void *base) const
{
TRACE_SANITIZE (this);
return_trace (c->check_struct (this) && value.sanitize (c, base));
}
HBGlyphID16 glyph; /* Last GlyphID */
T value; /* The lookup value (only one) */
public:
DEFINE_SIZE_STATIC (2 + T::static_size);
};
template <typename T>
struct LookupFormat6
{
friend struct Lookup<T>;
private:
const T* get_value (hb_codepoint_t glyph_id) const
{
const LookupSingle<T> *v = entries.bsearch (glyph_id);
return v ? &v->value : nullptr;
}
bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (entries.sanitize (c));
}
bool sanitize (hb_sanitize_context_t *c, const void *base) const
{
TRACE_SANITIZE (this);
return_trace (entries.sanitize (c, base));
}
protected:
HBUINT16 format; /* Format identifier--format = 6 */
VarSizedBinSearchArrayOf<LookupSingle<T>>
entries; /* The actual entries, sorted by glyph index. */
public:
DEFINE_SIZE_ARRAY (8, entries);
};
template <typename T>
struct LookupFormat8
{
friend struct Lookup<T>;
private:
const T* get_value (hb_codepoint_t glyph_id) const
{
return firstGlyph <= glyph_id && glyph_id - firstGlyph < glyphCount ?
&valueArrayZ[glyph_id - firstGlyph] : nullptr;
}
bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (c->check_struct (this) && valueArrayZ.sanitize (c, glyphCount));
}
bool sanitize (hb_sanitize_context_t *c, const void *base) const
{
TRACE_SANITIZE (this);
return_trace (c->check_struct (this) && valueArrayZ.sanitize (c, glyphCount, base));
}
protected:
HBUINT16 format; /* Format identifier--format = 8 */
HBGlyphID16 firstGlyph; /* First glyph index included in the trimmed array. */
HBUINT16 glyphCount; /* Total number of glyphs (equivalent to the last
* glyph minus the value of firstGlyph plus 1). */
UnsizedArrayOf<T>
valueArrayZ; /* The lookup values (indexed by the glyph index
* minus the value of firstGlyph). */
public:
DEFINE_SIZE_ARRAY (6, valueArrayZ);
};
template <typename T>
struct LookupFormat10
{
friend struct Lookup<T>;
private:
const typename T::type get_value_or_null (hb_codepoint_t glyph_id) const
{
if (!(firstGlyph <= glyph_id && glyph_id - firstGlyph < glyphCount))
return Null (T);
const HBUINT8 *p = &valueArrayZ[(glyph_id - firstGlyph) * valueSize];
unsigned int v = 0;
unsigned int count = valueSize;
for (unsigned int i = 0; i < count; i++)
v = (v << 8) | *p++;
return v;
}
bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (c->check_struct (this) &&
valueSize <= 4 &&
valueArrayZ.sanitize (c, glyphCount * valueSize));
}
protected:
HBUINT16 format; /* Format identifier--format = 8 */
HBUINT16 valueSize; /* Byte size of each value. */
HBGlyphID16 firstGlyph; /* First glyph index included in the trimmed array. */
HBUINT16 glyphCount; /* Total number of glyphs (equivalent to the last
* glyph minus the value of firstGlyph plus 1). */
UnsizedArrayOf<HBUINT8>
valueArrayZ; /* The lookup values (indexed by the glyph index
* minus the value of firstGlyph). */
public:
DEFINE_SIZE_ARRAY (8, valueArrayZ);
};
template <typename T>
struct Lookup
{
const T* get_value (hb_codepoint_t glyph_id, unsigned int num_glyphs) const
{
switch (u.format) {
case 0: return u.format0.get_value (glyph_id, num_glyphs);
case 2: return u.format2.get_value (glyph_id);
case 4: return u.format4.get_value (glyph_id);
case 6: return u.format6.get_value (glyph_id);
case 8: return u.format8.get_value (glyph_id);
default:return nullptr;
}
}
const typename T::type get_value_or_null (hb_codepoint_t glyph_id, unsigned int num_glyphs) const
{
switch (u.format) {
/* Format 10 cannot return a pointer. */
case 10: return u.format10.get_value_or_null (glyph_id);
default:
const T *v = get_value (glyph_id, num_glyphs);
return v ? *v : Null (T);
}
}
typename T::type get_class (hb_codepoint_t glyph_id,
unsigned int num_glyphs,
unsigned int outOfRange) const
{
const T *v = get_value (glyph_id, num_glyphs);
return v ? *v : outOfRange;
}
bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
if (!u.format.sanitize (c)) return_trace (false);
switch (u.format) {
case 0: return_trace (u.format0.sanitize (c));
case 2: return_trace (u.format2.sanitize (c));
case 4: return_trace (u.format4.sanitize (c));
case 6: return_trace (u.format6.sanitize (c));
case 8: return_trace (u.format8.sanitize (c));
case 10: return_trace (u.format10.sanitize (c));
default:return_trace (true);
}
}
bool sanitize (hb_sanitize_context_t *c, const void *base) const
{
TRACE_SANITIZE (this);
if (!u.format.sanitize (c)) return_trace (false);
switch (u.format) {
case 0: return_trace (u.format0.sanitize (c, base));
case 2: return_trace (u.format2.sanitize (c, base));
case 4: return_trace (u.format4.sanitize (c, base));
case 6: return_trace (u.format6.sanitize (c, base));
case 8: return_trace (u.format8.sanitize (c, base));
case 10: return_trace (false); /* We don't support format10 here currently. */
default:return_trace (true);
}
}
protected:
union {
HBUINT16 format; /* Format identifier */
LookupFormat0<T> format0;
LookupFormat2<T> format2;
LookupFormat4<T> format4;
LookupFormat6<T> format6;
LookupFormat8<T> format8;
LookupFormat10<T> format10;
} u;
public:
DEFINE_SIZE_UNION (2, format);
};
DECLARE_NULL_NAMESPACE_BYTES_TEMPLATE1 (AAT, Lookup, 2);
enum { DELETED_GLYPH = 0xFFFF };
/*
* (Extended) State Table
*/
template <typename T>
struct Entry
{
// This does seem like it's ever called.
bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
/* Note, we don't recurse-sanitize data because we don't access it.
* That said, in our DEFINE_SIZE_STATIC we access T::static_size,
* which ensures that data has a simple sanitize(). To be determined
* if I need to remove that as well.
*
* HOWEVER! Because we are a template, our DEFINE_SIZE_STATIC
* assertion wouldn't be checked, hence the line below. */
static_assert (T::static_size, "");
return_trace (c->check_struct (this));
}
public:
HBUINT16 newState; /* Byte offset from beginning of state table
* to the new state. Really?!?! Or just state
* number? The latter in morx for sure. */
HBUINT16 flags; /* Table specific. */
T data; /* Optional offsets to per-glyph tables. */
public:
DEFINE_SIZE_STATIC (4 + T::static_size);
};
template <>
struct Entry<void>
{
// This does seem like it's ever called.
bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (c->check_struct (this));
}
public:
HBUINT16 newState; /* Byte offset from beginning of state table to the new state. */
HBUINT16 flags; /* Table specific. */
public:
DEFINE_SIZE_STATIC (4);
};
template <typename Types, typename Extra>
struct StateTable
{
typedef typename Types::HBUINT HBUINT;
typedef typename Types::HBUSHORT HBUSHORT;
typedef typename Types::ClassTypeNarrow ClassType;
enum State
{
STATE_START_OF_TEXT = 0,
STATE_START_OF_LINE = 1,
};
enum Class
{
CLASS_END_OF_TEXT = 0,
CLASS_OUT_OF_BOUNDS = 1,
CLASS_DELETED_GLYPH = 2,
CLASS_END_OF_LINE = 3,
};
int new_state (unsigned int newState) const
{ return Types::extended ? newState : ((int) newState - (int) stateArrayTable) / (int) nClasses; }
unsigned int get_class (hb_codepoint_t glyph_id, unsigned int num_glyphs) const
{
if (unlikely (glyph_id == DELETED_GLYPH)) return CLASS_DELETED_GLYPH;
return (this+classTable).get_class (glyph_id, num_glyphs, 1);
}
const Entry<Extra> *get_entries () const
{ return (this+entryTable).arrayZ; }
const Entry<Extra> &get_entry (int state, unsigned int klass) const
{
if (unlikely (klass >= nClasses))
klass = StateTable::CLASS_OUT_OF_BOUNDS;
const HBUSHORT *states = (this+stateArrayTable).arrayZ;
const Entry<Extra> *entries = (this+entryTable).arrayZ;
unsigned int entry = states[state * nClasses + klass];
DEBUG_MSG (APPLY, nullptr, "e%u", entry);
return entries[entry];
}
bool sanitize (hb_sanitize_context_t *c,
unsigned int *num_entries_out = nullptr) const
{
TRACE_SANITIZE (this);
if (unlikely (!(c->check_struct (this) &&
nClasses >= 4 /* Ensure pre-defined classes fit. */ &&
classTable.sanitize (c, this)))) return_trace (false);
const HBUSHORT *states = (this+stateArrayTable).arrayZ;
const Entry<Extra> *entries = (this+entryTable).arrayZ;
unsigned int num_classes = nClasses;
if (unlikely (hb_unsigned_mul_overflows (num_classes, states[0].static_size)))
return_trace (false);
unsigned int row_stride = num_classes * states[0].static_size;
/* Apple 'kern' table has this peculiarity:
*
* "Because the stateTableOffset in the state table header is (strictly
* speaking) redundant, some 'kern' tables use it to record an initial
* state where that should not be StartOfText. To determine if this is
* done, calculate what the stateTableOffset should be. If it's different
* from the actual stateTableOffset, use it as the initial state."
*
* We implement this by calling the initial state zero, but allow *negative*
* states if the start state indeed was not the first state. Since the code
* is shared, this will also apply to 'mort' table. The 'kerx' / 'morx'
* tables are not affected since those address states by index, not offset.
*/
int min_state = 0;
int max_state = 0;
unsigned int num_entries = 0;
int state_pos = 0;
int state_neg = 0;
unsigned int entry = 0;
while (min_state < state_neg || state_pos <= max_state)
{
if (min_state < state_neg)
{
/* Negative states. */
if (unlikely (hb_unsigned_mul_overflows (min_state, num_classes)))
return_trace (false);
if (unlikely (!c->check_range (&states[min_state * num_classes],
-min_state,
row_stride)))
return_trace (false);
if ((c->max_ops -= state_neg - min_state) <= 0)
return_trace (false);
{ /* Sweep new states. */
const HBUSHORT *stop = &states[min_state * num_classes];
if (unlikely (stop > states))
return_trace (false);
for (const HBUSHORT *p = states; stop < p; p--)
num_entries = hb_max (num_entries, *(p - 1) + 1u);
state_neg = min_state;
}
}
if (state_pos <= max_state)
{
/* Positive states. */
if (unlikely (!c->check_range (states,
max_state + 1,
row_stride)))
return_trace (false);
if ((c->max_ops -= max_state - state_pos + 1) <= 0)
return_trace (false);
{ /* Sweep new states. */
if (unlikely (hb_unsigned_mul_overflows ((max_state + 1), num_classes)))
return_trace (false);
const HBUSHORT *stop = &states[(max_state + 1) * num_classes];
if (unlikely (stop < states))
return_trace (false);
for (const HBUSHORT *p = &states[state_pos * num_classes]; p < stop; p++)
num_entries = hb_max (num_entries, *p + 1u);
state_pos = max_state + 1;
}
}
if (unlikely (!c->check_array (entries, num_entries)))
return_trace (false);
if ((c->max_ops -= num_entries - entry) <= 0)
return_trace (false);
{ /* Sweep new entries. */
const Entry<Extra> *stop = &entries[num_entries];
for (const Entry<Extra> *p = &entries[entry]; p < stop; p++)
{
int newState = new_state (p->newState);
min_state = hb_min (min_state, newState);
max_state = hb_max (max_state, newState);
}
entry = num_entries;
}
}
if (num_entries_out)
*num_entries_out = num_entries;
return_trace (true);
}
protected:
HBUINT nClasses; /* Number of classes, which is the number of indices
* in a single line in the state array. */
NNOffsetTo<ClassType, HBUINT>
classTable; /* Offset to the class table. */
NNOffsetTo<UnsizedArrayOf<HBUSHORT>, HBUINT>
stateArrayTable;/* Offset to the state array. */
NNOffsetTo<UnsizedArrayOf<Entry<Extra>>, HBUINT>
entryTable; /* Offset to the entry array. */
public:
DEFINE_SIZE_STATIC (4 * sizeof (HBUINT));
};
template <typename HBUCHAR>
struct ClassTable
{
unsigned int get_class (hb_codepoint_t glyph_id, unsigned int outOfRange) const
{
unsigned int i = glyph_id - firstGlyph;
return i >= classArray.len ? outOfRange : classArray.arrayZ[i];
}
unsigned int get_class (hb_codepoint_t glyph_id,
unsigned int num_glyphs HB_UNUSED,
unsigned int outOfRange) const
{
return get_class (glyph_id, outOfRange);
}
bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (c->check_struct (this) && classArray.sanitize (c));
}
protected:
HBGlyphID16 firstGlyph; /* First glyph index included in the trimmed array. */
Array16Of<HBUCHAR> classArray; /* The class codes (indexed by glyph index minus
* firstGlyph). */
public:
DEFINE_SIZE_ARRAY (4, classArray);
};
struct ObsoleteTypes
{
static constexpr bool extended = false;
typedef HBUINT16 HBUINT;
typedef HBUINT8 HBUSHORT;
typedef ClassTable<HBUINT8> ClassTypeNarrow;
typedef ClassTable<HBUINT16> ClassTypeWide;
template <typename T>
static unsigned int offsetToIndex (unsigned int offset,
const void *base,
const T *array)
{
/* https://github.com/harfbuzz/harfbuzz/issues/3483 */
/* If offset is less than base, return an offset that would
* result in an address half a 32bit address-space away,
* to make sure sanitize fails even on 32bit builds. */
if (unlikely (offset < unsigned ((const char *) array - (const char *) base)))
return INT_MAX / T::static_size;
/* https://github.com/harfbuzz/harfbuzz/issues/2816 */
return (offset - unsigned ((const char *) array - (const char *) base)) / T::static_size;
}
template <typename T>
static unsigned int byteOffsetToIndex (unsigned int offset,
const void *base,
const T *array)
{
return offsetToIndex (offset, base, array);
}
template <typename T>
static unsigned int wordOffsetToIndex (unsigned int offset,
const void *base,
const T *array)
{
return offsetToIndex (2 * offset, base, array);
}
};
struct ExtendedTypes
{
static constexpr bool extended = true;
typedef HBUINT32 HBUINT;
typedef HBUINT16 HBUSHORT;
typedef Lookup<HBUINT16> ClassTypeNarrow;
typedef Lookup<HBUINT16> ClassTypeWide;
template <typename T>
static unsigned int offsetToIndex (unsigned int offset,
const void *base HB_UNUSED,
const T *array HB_UNUSED)
{
return offset;
}
template <typename T>
static unsigned int byteOffsetToIndex (unsigned int offset,
const void *base HB_UNUSED,
const T *array HB_UNUSED)
{
return offset / 2;
}
template <typename T>
static unsigned int wordOffsetToIndex (unsigned int offset,
const void *base HB_UNUSED,
const T *array HB_UNUSED)
{
return offset;
}
};
template <typename Types, typename EntryData>
struct StateTableDriver
{
using StateTableT = StateTable<Types, EntryData>;
using EntryT = Entry<EntryData>;
StateTableDriver (const StateTableT &machine_,
hb_buffer_t *buffer_,
hb_face_t *face_) :
machine (machine_),
buffer (buffer_),
num_glyphs (face_->get_num_glyphs ()) {}
template <typename context_t>
void drive (context_t *c, hb_aat_apply_context_t *ac)
{
if (!c->in_place)
buffer->clear_output ();
int state = StateTableT::STATE_START_OF_TEXT;
// If there's only one range, we already checked the flag.
auto *last_range = ac->range_flags && (ac->range_flags->length > 1) ? &(*ac->range_flags)[0] : nullptr;
for (buffer->idx = 0; buffer->successful;)
{
/* This block is copied in NoncontextualSubtable::apply. Keep in sync. */
if (last_range)
{
auto *range = last_range;
if (buffer->idx < buffer->len)
{
unsigned cluster = buffer->cur().cluster;
while (cluster < range->cluster_first)
range--;
while (cluster > range->cluster_last)
range++;
last_range = range;
}
if (!(range->flags & ac->subtable_flags))
{
if (buffer->idx == buffer->len || unlikely (!buffer->successful))
break;
state = StateTableT::STATE_START_OF_TEXT;
(void) buffer->next_glyph ();
continue;
}
}
unsigned int klass = buffer->idx < buffer->len ?
machine.get_class (buffer->cur().codepoint, num_glyphs) :
(unsigned) StateTableT::CLASS_END_OF_TEXT;
DEBUG_MSG (APPLY, nullptr, "c%u at %u", klass, buffer->idx);
const EntryT &entry = machine.get_entry (state, klass);
const int next_state = machine.new_state (entry.newState);
/* Conditions under which it's guaranteed safe-to-break before current glyph:
*
* 1. There was no action in this transition; and
*
* 2. If we break before current glyph, the results will be the same. That
* is guaranteed if:
*
* 2a. We were already in start-of-text state; or
*
* 2b. We are epsilon-transitioning to start-of-text state; or
*
* 2c. Starting from start-of-text state seeing current glyph:
*
* 2c'. There won't be any actions; and
*
* 2c". We would end up in the same state that we were going to end up
* in now, including whether epsilon-transitioning.
*
* and
*
* 3. If we break before current glyph, there won't be any end-of-text action
* after previous glyph.
*
* This triples the transitions we need to look up, but is worth returning
* granular unsafe-to-break results. See eg.:
*
* https://github.com/harfbuzz/harfbuzz/issues/2860
*/
const EntryT *wouldbe_entry;
bool safe_to_break =
/* 1. */
!c->is_actionable (this, entry)
&&
/* 2. */
(
/* 2a. */
state == StateTableT::STATE_START_OF_TEXT
||
/* 2b. */
(
(entry.flags & context_t::DontAdvance) &&
next_state == StateTableT::STATE_START_OF_TEXT
)
||
/* 2c. */
(
wouldbe_entry = &machine.get_entry (StateTableT::STATE_START_OF_TEXT, klass)
,
/* 2c'. */
!c->is_actionable (this, *wouldbe_entry)
&&
/* 2c". */
(
next_state == machine.new_state (wouldbe_entry->newState)
&&
(entry.flags & context_t::DontAdvance) == (wouldbe_entry->flags & context_t::DontAdvance)
)
)
)
&&
/* 3. */
!c->is_actionable (this, machine.get_entry (state, StateTableT::CLASS_END_OF_TEXT))
;
if (!safe_to_break && buffer->backtrack_len () && buffer->idx < buffer->len)
buffer->unsafe_to_break_from_outbuffer (buffer->backtrack_len () - 1, buffer->idx + 1);
c->transition (this, entry);
state = next_state;
DEBUG_MSG (APPLY, nullptr, "s%d", state);
if (buffer->idx == buffer->len || unlikely (!buffer->successful))
break;
if (!(entry.flags & context_t::DontAdvance) || buffer->max_ops-- <= 0)
(void) buffer->next_glyph ();
}
if (!c->in_place)
buffer->sync ();
}
public:
const StateTableT &machine;
hb_buffer_t *buffer;
unsigned int num_glyphs;
};
} /* namespace AAT */
#endif /* HB_AAT_LAYOUT_COMMON_HH */