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Avoid parsing subtable if coverage check fails #320

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8e6cfe8
Avoid parsing subtable if coverage check fails
dfrg Jan 5, 2026
a1f9afa
clippy
dfrg Jan 5, 2026
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91 changes: 19 additions & 72 deletions src/hb/ot/contextual.rs
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Original file line number Diff line number Diff line change
@@ -1,10 +1,10 @@
use super::{coverage_binary_cached, coverage_index, covered, glyph_class};
use super::{coverage_index, covered, glyph_class};
use crate::hb::buffer::GlyphInfo;
use crate::hb::ot::{ClassDefInfo, CoverageInfo};
use crate::hb::ot::ClassDefInfo;
use crate::hb::ot_layout_gsubgpos::OT::hb_ot_apply_context_t;
use crate::hb::ot_layout_gsubgpos::{
apply_lookup, match_always, match_backtrack, match_glyph, match_input, match_lookahead,
may_skip_t, skipping_iterator_t, Apply, BinaryCache, ChainContextFormat2Cache,
may_skip_t, skipping_iterator_t, Apply, ApplyState, ChainContextFormat2Cache,
ContextFormat2Cache, SubtableExternalCache, SubtableExternalCacheMode, WouldApply,
WouldApplyContext,
};
Expand Down Expand Up @@ -47,9 +47,8 @@ impl WouldApply for SequenceContextFormat1<'_> {
}

impl Apply for SequenceContextFormat1<'_> {
fn apply(&self, ctx: &mut hb_ot_apply_context_t) -> Option<()> {
let glyph = ctx.buffer.cur(0).as_glyph();
let index = self.coverage().ok()?.get(glyph)? as usize;
fn apply(&self, ctx: &mut hb_ot_apply_context_t, state: &ApplyState) -> Option<()> {
let index = state.first_coverage_index as usize;
let set = self.seq_rule_sets().get(index)?.ok()?;
apply_context_rules(ctx, &set.seq_rules(), match_glyph)
}
Expand Down Expand Up @@ -85,44 +84,24 @@ impl WouldApply for SequenceContextFormat2<'_> {
}

impl Apply for SequenceContextFormat2<'_> {
fn apply_with_external_cache(
&self,
ctx: &mut hb_ot_apply_context_t,
external_cache: &SubtableExternalCache,
) -> Option<()> {
let glyph = ctx.buffer.cur(0).as_glyph();
let SubtableExternalCache::ContextFormat2Cache(cache) = external_cache else {
fn apply(&self, ctx: &mut hb_ot_apply_context_t, state: &ApplyState) -> Option<()> {
let SubtableExternalCache::ContextFormat2Cache(cache) = state.external_cache else {
return None;
};
let offset_data = self.offset_data();
coverage_binary_cached(
|gid| cache.coverage.index(&offset_data, gid),
glyph,
&cache.coverage_cache,
)?;
let input_class = |gid| cache.input.class(&offset_data, gid);
let index = input_class(glyph) as usize;
let index = input_class(state.first_glyph) as usize;
let set = self.class_seq_rule_sets().get(index)?.ok()?;
apply_context_rules(ctx, &set.class_seq_rules(), |info, value| {
input_class(info.as_glyph()) == value
})
}

fn apply_cached(
&self,
ctx: &mut hb_ot_apply_context_t,
external_cache: &SubtableExternalCache,
) -> Option<()> {
let glyph = ctx.buffer.cur(0).as_glyph();
let SubtableExternalCache::ContextFormat2Cache(cache) = external_cache else {
fn apply_cached(&self, ctx: &mut hb_ot_apply_context_t, state: &ApplyState) -> Option<()> {
let SubtableExternalCache::ContextFormat2Cache(cache) = state.external_cache else {
return None;
};
let offset_data = self.offset_data();
coverage_binary_cached(
|gid| cache.coverage.index(&offset_data, gid),
glyph,
&cache.coverage_cache,
)?;
let input_class = |gid| cache.input.class(&offset_data, gid);
let index = get_class_cached(&input_class, &mut ctx.buffer.info[ctx.buffer.idx]) as usize;
let set = self.class_seq_rule_sets().get(index)?.ok()?;
Expand All @@ -142,9 +121,6 @@ impl Apply for SequenceContextFormat2<'_> {
fn external_cache_create(&self, _mode: SubtableExternalCacheMode) -> SubtableExternalCache {
let data = self.offset_data();
SubtableExternalCache::ContextFormat2Cache(ContextFormat2Cache {
coverage_cache: BinaryCache::new(),
coverage: CoverageInfo::new(&data, self.coverage_offset().to_u32() as u16)
.unwrap_or_default(),
input: ClassDefInfo::new(&data, self.class_def_offset().to_u32() as u16)
.unwrap_or_default(),
})
Expand All @@ -163,10 +139,8 @@ impl WouldApply for SequenceContextFormat3<'_> {
}

impl Apply for SequenceContextFormat3<'_> {
fn apply(&self, ctx: &mut hb_ot_apply_context_t) -> Option<()> {
let glyph = ctx.buffer.cur(0).as_glyph();
fn apply(&self, ctx: &mut hb_ot_apply_context_t, _state: &ApplyState) -> Option<()> {
let input_coverages = self.coverages();
input_coverages.get(0).ok()?.get(glyph)?;
let input = |info: &mut GlyphInfo, index: u16| {
input_coverages
.get(index as usize + 1)
Expand Down Expand Up @@ -230,9 +204,8 @@ impl WouldApply for ChainedSequenceContextFormat1<'_> {
}

impl Apply for ChainedSequenceContextFormat1<'_> {
fn apply(&self, ctx: &mut hb_ot_apply_context_t) -> Option<()> {
let glyph = ctx.buffer.cur(0).as_glyph();
let index = self.coverage().ok()?.get(glyph)? as usize;
fn apply(&self, ctx: &mut hb_ot_apply_context_t, state: &ApplyState) -> Option<()> {
let index = state.first_coverage_index as usize;
let set = self.chained_seq_rule_sets().get(index)?.ok()?;
apply_chain_context_rules(
ctx,
Expand Down Expand Up @@ -344,22 +317,12 @@ fn match_class_cached2<'a>(
}

impl Apply for ChainedSequenceContextFormat2<'_> {
fn apply_with_external_cache(
&self,
ctx: &mut hb_ot_apply_context_t,
external_cache: &SubtableExternalCache,
) -> Option<()> {
let glyph = ctx.buffer.cur(0).as_glyph();
let SubtableExternalCache::ChainContextFormat2Cache(cache) = external_cache else {
fn apply(&self, ctx: &mut hb_ot_apply_context_t, state: &ApplyState) -> Option<()> {
let SubtableExternalCache::ChainContextFormat2Cache(cache) = state.external_cache else {
return None;
};
let offset_data = self.offset_data();
coverage_binary_cached(
|gid| cache.coverage.index(&offset_data, gid),
glyph,
&cache.coverage_cache,
)?;
let index = cache.input.class(&offset_data, glyph) as usize;
let index = cache.input.class(&offset_data, state.first_glyph) as usize;
let set = self.chained_class_seq_rule_sets().get(index)?.ok()?;
apply_chain_context_rules(
ctx,
Expand All @@ -371,21 +334,11 @@ impl Apply for ChainedSequenceContextFormat2<'_> {
),
)
}
fn apply_cached(
&self,
ctx: &mut hb_ot_apply_context_t,
external_cache: &SubtableExternalCache,
) -> Option<()> {
let glyph = ctx.buffer.cur(0).as_glyph();
let SubtableExternalCache::ChainContextFormat2Cache(cache) = external_cache else {
fn apply_cached(&self, ctx: &mut hb_ot_apply_context_t, state: &ApplyState) -> Option<()> {
let SubtableExternalCache::ChainContextFormat2Cache(cache) = state.external_cache else {
return None;
};
let offset_data = self.offset_data();
coverage_binary_cached(
|gid| cache.coverage.index(&offset_data, gid),
glyph,
&cache.coverage_cache,
)?;
let input_class = |gid| cache.input.class(&offset_data, gid);
let lookahead_class = |gid| cache.lookahead.class(&offset_data, gid);
let index = get_class_cached2(&input_class, &mut ctx.buffer.info[ctx.buffer.idx]) as usize;
Expand Down Expand Up @@ -413,9 +366,6 @@ impl Apply for ChainedSequenceContextFormat2<'_> {
fn external_cache_create(&self, _mode: SubtableExternalCacheMode) -> SubtableExternalCache {
let data = self.offset_data();
SubtableExternalCache::ChainContextFormat2Cache(ChainContextFormat2Cache {
coverage_cache: BinaryCache::new(),
coverage: CoverageInfo::new(&data, self.coverage_offset().to_u32() as u16)
.unwrap_or_default(),
backtrack: ClassDefInfo::new(&data, self.backtrack_class_def_offset().to_u32() as u16)
.unwrap_or_default(),
input: ClassDefInfo::new(&data, self.input_class_def_offset().to_u32() as u16)
Expand Down Expand Up @@ -446,11 +396,8 @@ impl WouldApply for ChainedSequenceContextFormat3<'_> {
}

impl Apply for ChainedSequenceContextFormat3<'_> {
fn apply(&self, ctx: &mut hb_ot_apply_context_t) -> Option<()> {
let glyph = ctx.buffer.cur(0).as_glyph();

fn apply(&self, ctx: &mut hb_ot_apply_context_t, _state: &ApplyState) -> Option<()> {
let input_coverages = self.input_coverages();
input_coverages.get(0).ok()?.get(glyph)?;

let backtrack_coverages = self.backtrack_coverages();
let lookahead_coverages = self.lookahead_coverages();
Expand Down
11 changes: 4 additions & 7 deletions src/hb/ot/gpos/cursive.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,16 +2,13 @@ use crate::hb::buffer::HB_BUFFER_SCRATCH_FLAG_HAS_GPOS_ATTACHMENT;
use crate::hb::ot_layout_common::lookup_flags;
use crate::hb::ot_layout_gpos_table::attach_type;
use crate::hb::ot_layout_gsubgpos::OT::hb_ot_apply_context_t;
use crate::hb::ot_layout_gsubgpos::{skipping_iterator_t, Apply};
use crate::hb::ot_layout_gsubgpos::{skipping_iterator_t, Apply, ApplyState};
use crate::{Direction, GlyphPosition};
use read_fonts::tables::gpos::CursivePosFormat1;

impl Apply for CursivePosFormat1<'_> {
fn apply(&self, ctx: &mut hb_ot_apply_context_t) -> Option<()> {
let this = ctx.buffer.cur(0).as_glyph();

let coverage = self.coverage().ok()?;
let index_this = coverage.get(this)? as usize;
fn apply(&self, ctx: &mut hb_ot_apply_context_t, state: &ApplyState) -> Option<()> {
let index_this = state.first_coverage_index as usize;
let records = self.entry_exit_record();
let offset_data = self.offset_data();
let entry_this = records.get(index_this)?.entry_anchor(offset_data)?.ok()?;
Expand All @@ -28,7 +25,7 @@ impl Apply for CursivePosFormat1<'_> {

let i = iter.index();
let prev = iter.buffer.info[i].as_glyph();
let index_prev = coverage.get(prev)? as usize;
let index_prev = state.coverage.index(&self.offset_data(), prev)? as usize;
let Some(exit_prev) = records
.get(index_prev)
.and_then(|rec| rec.exit_anchor(offset_data).transpose().ok().flatten())
Expand Down
17 changes: 7 additions & 10 deletions src/hb/ot/gpos/mark.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ use crate::hb::buffer::{hb_buffer_t, HB_BUFFER_SCRATCH_FLAG_HAS_GPOS_ATTACHMENT}
use crate::hb::ot_layout_common::lookup_flags;
use crate::hb::ot_layout_gpos_table::attach_type;
use crate::hb::ot_layout_gsubgpos::OT::hb_ot_apply_context_t;
use crate::hb::ot_layout_gsubgpos::{match_t, skipping_iterator_t, Apply, MatchSource};
use crate::hb::ot_layout_gsubgpos::{match_t, skipping_iterator_t, Apply, ApplyState, MatchSource};
use read_fonts::tables::gpos::{
AnchorTable, MarkArray, MarkBasePosFormat1, MarkLigPosFormat1, MarkMarkPosFormat1,
};
Expand Down Expand Up @@ -49,9 +49,8 @@ impl MarkArrayExt for MarkArray<'_> {
}

impl Apply for MarkBasePosFormat1<'_> {
fn apply(&self, ctx: &mut hb_ot_apply_context_t) -> Option<()> {
let mark_glyph = ctx.buffer.cur(0).as_glyph();
let mark_index = self.mark_coverage().ok()?.get(mark_glyph)?;
fn apply(&self, ctx: &mut hb_ot_apply_context_t, state: &ApplyState) -> Option<()> {
let mark_index = state.first_coverage_index;

let base_coverage = self.base_coverage().ok()?;
let last_base_until = ctx.last_base_until;
Expand Down Expand Up @@ -142,9 +141,8 @@ fn accept(buffer: &hb_buffer_t, idx: usize) -> bool {
}

impl Apply for MarkMarkPosFormat1<'_> {
fn apply(&self, ctx: &mut hb_ot_apply_context_t) -> Option<()> {
let mark1_glyph = ctx.buffer.cur(0).as_glyph();
let mark1_index = self.mark1_coverage().ok()?.get(mark1_glyph)?;
fn apply(&self, ctx: &mut hb_ot_apply_context_t, state: &ApplyState) -> Option<()> {
let mark1_index = state.first_coverage_index;
let lookup_props = ctx.lookup_props;
// Now we search backwards for a suitable mark glyph until a non-mark glyph
let mut iter = skipping_iterator_t::new(ctx, false);
Expand Down Expand Up @@ -205,9 +203,8 @@ impl Apply for MarkMarkPosFormat1<'_> {
}

impl Apply for MarkLigPosFormat1<'_> {
fn apply(&self, ctx: &mut hb_ot_apply_context_t) -> Option<()> {
let mark_glyph = ctx.buffer.cur(0).as_glyph();
let mark_index = self.mark_coverage().ok()?.get(mark_glyph)? as usize;
fn apply(&self, ctx: &mut hb_ot_apply_context_t, state: &ApplyState) -> Option<()> {
let mark_index = state.first_coverage_index as usize;

// Due to borrowing rules, we have this piece of code before creating the
// iterator, unlike in harfbuzz.
Expand Down
71 changes: 9 additions & 62 deletions src/hb/ot/gpos/pair.rs
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Original file line number Diff line number Diff line change
@@ -1,32 +1,16 @@
use crate::hb::ot::{coverage_index, coverage_index_cached, ClassDefInfo, CoverageInfo};
use crate::hb::ot::ClassDefInfo;
use crate::hb::ot::{glyph_class, glyph_class_cached};
use crate::hb::ot_layout_gsubgpos::OT::hb_ot_apply_context_t;
use crate::hb::ot_layout_gsubgpos::{
skipping_iterator_t, Apply, PairPosFormat1Cache, PairPosFormat1SmallCache, PairPosFormat2Cache,
PairPosFormat2SmallCache, SubtableExternalCache, SubtableExternalCacheMode,
skipping_iterator_t, Apply, ApplyState, PairPosFormat2Cache, PairPosFormat2SmallCache,
SubtableExternalCache, SubtableExternalCacheMode,
};
use alloc::boxed::Box;
use read_fonts::tables::gpos::{PairPosFormat1, PairPosFormat2};

impl Apply for PairPosFormat1<'_> {
fn apply_with_external_cache(
&self,
ctx: &mut hb_ot_apply_context_t,
external_cache: &SubtableExternalCache,
) -> Option<()> {
let first_glyph = ctx.buffer.cur(0).as_glyph();

let first_glyph_coverage_index = match external_cache {
SubtableExternalCache::PairPosFormat1Cache(cache) => coverage_index_cached(
|gid| self.coverage().ok()?.get(gid),
first_glyph,
&cache.coverage,
)?,
SubtableExternalCache::PairPosFormat1SmallCache(cache) => {
cache.coverage.index(&self.offset_data(), first_glyph)?
}
_ => coverage_index(self.coverage(), first_glyph)?,
};
fn apply(&self, ctx: &mut hb_ot_apply_context_t, state: &ApplyState) -> Option<()> {
let first_glyph_coverage_index = state.first_coverage_index;

let mut iter = skipping_iterator_t::new(ctx, false);
iter.reset(iter.buffer.idx);
Expand Down Expand Up @@ -120,46 +104,11 @@ impl Apply for PairPosFormat1<'_> {
}
None
}

fn external_cache_create(&self, mode: SubtableExternalCacheMode) -> SubtableExternalCache {
match mode {
SubtableExternalCacheMode::Full => {
SubtableExternalCache::PairPosFormat1Cache(Box::new(PairPosFormat1Cache::new()))
}
SubtableExternalCacheMode::Small => {
if let Some(coverage) =
CoverageInfo::new(&self.offset_data(), self.coverage_offset().to_u32() as u16)
{
SubtableExternalCache::PairPosFormat1SmallCache(PairPosFormat1SmallCache {
coverage,
})
} else {
SubtableExternalCache::None
}
}
SubtableExternalCacheMode::None => SubtableExternalCache::None,
}
}
}

impl Apply for PairPosFormat2<'_> {
fn apply_with_external_cache(
&self,
ctx: &mut hb_ot_apply_context_t,
external_cache: &SubtableExternalCache,
) -> Option<()> {
let first_glyph = ctx.buffer.cur(0).as_glyph();
match external_cache {
SubtableExternalCache::PairPosFormat2Cache(cache) => coverage_index_cached(
|gid| self.coverage().ok()?.get(gid),
first_glyph,
&cache.coverage,
)?,
SubtableExternalCache::PairPosFormat2SmallCache(cache) => {
cache.coverage.index(&self.offset_data(), first_glyph)?
}
_ => coverage_index(self.coverage(), first_glyph)?,
};
fn apply(&self, ctx: &mut hb_ot_apply_context_t, state: &ApplyState) -> Option<()> {
let first_glyph = state.first_glyph;
let mut iter = skipping_iterator_t::new(ctx, false);
iter.reset(iter.buffer.idx);

Expand Down Expand Up @@ -204,7 +153,7 @@ impl Apply for PairPosFormat2<'_> {
}
};
let data = self.offset_data();
let (class1, class2) = match external_cache {
let (class1, class2) = match state.external_cache {
SubtableExternalCache::PairPosFormat2Cache(cache) => (
glyph_class_cached(
|gid| glyph_class(self.class_def1(), gid),
Expand Down Expand Up @@ -256,12 +205,10 @@ impl Apply for PairPosFormat2<'_> {
}
SubtableExternalCacheMode::Small => {
let data = self.offset_data();
let coverage = CoverageInfo::new(&data, self.coverage_offset().to_u32() as u16);
let class1 = ClassDefInfo::new(&data, self.class_def1_offset().to_u32() as u16);
let class2 = ClassDefInfo::new(&data, self.class_def2_offset().to_u32() as u16);
if let Some((coverage, (first, second))) = coverage.zip(class1.zip(class2)) {
if let Some((first, second)) = class1.zip(class2) {
SubtableExternalCache::PairPosFormat2SmallCache(PairPosFormat2SmallCache {
coverage,
first,
second,
})
Expand Down
11 changes: 4 additions & 7 deletions src/hb/ot/gpos/single.rs
View file
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Original file line number Diff line number Diff line change
@@ -1,11 +1,9 @@
use crate::hb::ot_layout_gsubgpos::Apply;
use crate::hb::ot_layout_gsubgpos::OT::hb_ot_apply_context_t;
use crate::hb::ot_layout_gsubgpos::{Apply, ApplyState};
use read_fonts::tables::gpos::{SinglePosFormat1, SinglePosFormat2};

impl Apply for SinglePosFormat1<'_> {
fn apply(&self, ctx: &mut hb_ot_apply_context_t) -> Option<()> {
let glyph = ctx.buffer.cur(0).as_glyph();
self.coverage().ok()?.get(glyph)?;
fn apply(&self, ctx: &mut hb_ot_apply_context_t, _state: &ApplyState) -> Option<()> {
let format = self.value_format();
let offset = self.shape().value_record_byte_range().start;
super::apply_value(ctx, ctx.buffer.idx, &self.offset_data(), offset, format);
Expand All @@ -15,9 +13,8 @@ impl Apply for SinglePosFormat1<'_> {
}

impl Apply for SinglePosFormat2<'_> {
fn apply(&self, ctx: &mut hb_ot_apply_context_t) -> Option<()> {
let glyph = ctx.buffer.cur(0).as_glyph();
let index = self.coverage().ok()?.get(glyph)? as usize;
fn apply(&self, ctx: &mut hb_ot_apply_context_t, state: &ApplyState) -> Option<()> {
let index = state.first_coverage_index as usize;
let format = self.value_format();
let offset =
self.shape().value_records_byte_range().start + (format.record_byte_len() * index);
Expand Down
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