diff options
Diffstat (limited to 'thirdparty/harfbuzz/src/hb-aat-layout-common.hh')
| -rw-r--r-- | thirdparty/harfbuzz/src/hb-aat-layout-common.hh | 885 |
1 files changed, 885 insertions, 0 deletions
diff --git a/thirdparty/harfbuzz/src/hb-aat-layout-common.hh b/thirdparty/harfbuzz/src/hb-aat-layout-common.hh new file mode 100644 index 0000000000..98ed20d8eb --- /dev/null +++ b/thirdparty/harfbuzz/src/hb-aat-layout-common.hh @@ -0,0 +1,885 @@ +/* + * 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-open-type.hh" + + +namespace AAT { + +using namespace OT; + + +/* + * 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)); + } + + HBGlyphID last; /* Last GlyphID in this segment */ + HBGlyphID 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, hb_forward<Ts> (ds)...)); + } + + HBGlyphID last; /* Last GlyphID in this segment */ + HBGlyphID first; /* First GlyphID in this segment */ + NNOffsetTo<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)); + } + + HBGlyphID 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 */ + HBGlyphID 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. */ + HBGlyphID 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); +}; +/* Lookup 0 has unbounded size (dependant on num_glyphs). So we need to defined + * special NULL objects for Lookup<> objects, but since it's template our macros + * don't work. So we have to hand-code them here. UGLY. */ +} /* Close namespace. */ +/* Ugly hand-coded null objects for template Lookup<> :(. */ +extern HB_INTERNAL const unsigned char _hb_Null_AAT_Lookup[2]; +template <typename T> +struct Null<AAT::Lookup<T>> { + static AAT::Lookup<T> const & get_null () + { return *reinterpret_cast<const AAT::Lookup<T> *> (_hb_Null_AAT_Lookup); } +}; +namespace AAT { + +enum { DELETED_GLYPH = 0xFFFF }; + +/* + * (Extended) State Table + */ + +template <typename T> +struct Entry +{ + bool sanitize (hb_sanitize_context_t *c, unsigned int count) 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> +{ + bool sanitize (hb_sanitize_context_t *c, unsigned int count /*XXX Unused?*/) 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: + HBGlyphID firstGlyph; /* First glyph index included in the trimmed array. */ + ArrayOf<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) + { + return (offset - ((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) + { + if (!c->in_place) + buffer->clear_output (); + + int state = StateTableT::STATE_START_OF_TEXT; + for (buffer->idx = 0; buffer->successful;) + { + unsigned int klass = buffer->idx < buffer->len ? + machine.get_class (buffer->info[buffer->idx].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->swap_buffers (); + } + + public: + const StateTableT &machine; + hb_buffer_t *buffer; + unsigned int num_glyphs; +}; + + +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; + + /* 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; } +}; + + +} /* namespace AAT */ + + +#endif /* HB_AAT_LAYOUT_COMMON_HH */ |