[HB] Implement backtrack matching
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02e1e5c63f
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@ -71,19 +71,36 @@ static inline bool match_coverage (hb_codepoint_t glyph_id, const USHORT &value,
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}
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static inline bool match_backtrack (LOOKUP_ARGS_DEF,
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unsigned int count,
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const USHORT backtrack[],
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match_func_t match_func,
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char *match_data)
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{
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unsigned int i, j;
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for (i = 0, j = buffer->out_pos - 1; i < count; i++, j--) {
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while (!_hb_ot_layout_check_glyph_property (layout, OUT_ITEM (j), lookup_flag, &property)) {
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if (HB_UNLIKELY (j + 1 == count - i))
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return false;
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j--;
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}
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if (HB_LIKELY (match_func (OUT_GLYPH(j), backtrack[i], match_data)))
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return false;
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}
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return true;
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}
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static inline bool match_input (LOOKUP_ARGS_DEF,
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USHORT inputCount, /* Including the first glyph (not matched) */
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unsigned int count, /* Including the first glyph (not matched) */
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const USHORT input[], /* Array of input values--start with second glyph */
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match_func_t match_func,
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char *match_data,
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unsigned int *context_length_out)
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{
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unsigned int i, j;
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unsigned int count = inputCount;
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if (HB_UNLIKELY (buffer->in_pos + count > buffer->in_length ||
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context_length < count))
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return false; /* Not enough glyphs in input or context */
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/* XXX context_length should also be checked when skipping glyphs, right?
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* What does context_length really mean, anyway? */
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@ -116,12 +133,11 @@ struct LookupRecord {
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ASSERT_SIZE (LookupRecord, 4);
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static inline bool apply_lookup (LOOKUP_ARGS_DEF,
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USHORT inputCount, /* Including the first glyph */
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USHORT lookupCount,
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unsigned int count, /* Including the first glyph */
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unsigned int lookupCount,
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const LookupRecord lookupRecord[], /* Array of LookupRecords--in design order */
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apply_lookup_func_t apply_func)
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{
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unsigned int count = inputCount;
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unsigned int record_count = lookupCount;
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const LookupRecord *record = lookupRecord;
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@ -165,12 +181,17 @@ struct ContextLookupContext {
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};
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static inline bool context_lookup (LOOKUP_ARGS_DEF,
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USHORT inputCount, /* Including the first glyph (not matched) */
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unsigned int inputCount, /* Including the first glyph (not matched) */
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const USHORT input[], /* Array of input values--start with second glyph */
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USHORT lookupCount,
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unsigned int lookupCount,
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const LookupRecord lookupRecord[],
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ContextLookupContext &context)
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{
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/* First guess */
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if (HB_UNLIKELY (buffer->in_pos + inputCount > buffer->in_length ||
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context_length < inputCount))
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return false;
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return match_input (LOOKUP_ARGS,
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inputCount, input,
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context.funcs.match, context.match_data,
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@ -370,17 +391,25 @@ struct ChainContextLookupContext {
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};
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static inline bool chain_context_lookup (LOOKUP_ARGS_DEF,
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USHORT backtrackCount,
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unsigned int backtrackCount,
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const USHORT backtrack[],
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USHORT inputCount, /* Including the first glyph (not matched) */
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unsigned int inputCount, /* Including the first glyph (not matched) */
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const USHORT input[], /* Array of input values--start with second glyph */
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USHORT lookaheadCount,
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unsigned int lookaheadCount,
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const USHORT lookahead[],
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USHORT lookupCount,
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unsigned int lookupCount,
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const LookupRecord lookupRecord[],
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ChainContextLookupContext &context)
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{
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return match_input (LOOKUP_ARGS,
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/* First guess */
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if (HB_UNLIKELY (buffer->out_pos < backtrackCount ||
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buffer->in_pos + inputCount + lookaheadCount > buffer->in_length))
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return false;
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return match_backtrack (LOOKUP_ARGS,
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backtrackCount, backtrack,
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context.funcs.match, context.match_data[0]) &&
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match_input (LOOKUP_ARGS,
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inputCount, input,
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context.funcs.match, context.match_data[1],
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&context_length) &&
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