84043bd9b0
The CMAP skip check for unmapped glyphs was already implemented in
commit 7660cfc8 (bead bf-4zgpr). This note documents the verification
of that implementation.
Acceptance criteria verified:
- Code checks glyph name against unmapped_glyph_names ✓
- Unmapped glyphs are skipped during CMAP generation ✓
- Skip happens cleanly (no errors, no panics) ✓
- Code compiles without errors ✓
See notes/bf-3s7gd.md for details.
86 lines
3.2 KiB
Markdown
86 lines
3.2 KiB
Markdown
# bf-3s7gd: CMAP skip check for unmapped glyphs
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## Status: ALREADY IMPLEMENTED
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This bead's work was already completed in a previous iteration. The skip logic was implemented in commit `7660cfc8` (bead `bf-4zgpr`), which refactored an earlier implementation.
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## Implementation location
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File: `crates/pdftract-core/src/font/encoding.rs`
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Lines 224-229:
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```rust
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// Skip unmapped glyph names (e.g., .notdef) to prevent them from
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// appearing in text extraction output. These glyphs have no valid
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// Unicode mapping and should emit GLYPH_UNMAPPED diagnostics instead.
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if !overlay.is_unmapped_glyph_name(&name) {
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overlay.entries.push((cursor as u8, Arc::clone(name)));
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}
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```
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## Supporting infrastructure
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1. **Unmapped glyph names configuration** (`unmapped.rs`):
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- `is_unmapped_glyph_name(name: &str) -> bool` - checks against global UNMAPPED_GLYPH_NAMES set
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- Handles glyph names with or without leading `/`
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2. **DifferencesOverlay instance method** (`encoding.rs` lines 274-282):
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```rust
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fn is_unmapped_glyph_name(&self, name: &str) -> bool {
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let clean_name = if name.starts_with('/') {
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&name[1..]
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} else {
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name
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};
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self.unmapped_glyph_names.contains(clean_name)
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}
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```
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3. **Configuration field** (`encoding.rs` lines 136, 164-168):
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- `unmapped_glyph_names: HashSet<String>` - stores the set of glyph names to skip
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- Defaults to global `UNMAPPED_GLYPH_NAMES` set
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- Can be customized via `with_unmapped_glyph_names()` constructor
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## Acceptance criteria verification
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- ✅ **Code checks glyph name against unmapped_glyph_names before CMAP entry creation**
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- Lines 227: `if !overlay.is_unmapped_glyph_name(&name)`
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- ✅ **Unmapped glyphs are skipped during CMAP generation**
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- Lines 227-229: If glyph is unmapped, `entries.push()` is skipped
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- ✅ **Skip happens cleanly (no errors, no panics)**
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- Tests pass: `test_differences_overlay_skips_notdef`, `test_differences_overlay_skips_notdef_with_slash`
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- No diagnostics emitted for skipped glyphs
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- ✅ **Code compiles without errors**
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- `cargo test -p pdftract-core --lib differences_overlay_skips_notdef` passes
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## Test results
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```bash
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$ cargo test -p pdftract-core --lib differences_overlay_skips_notdef --no-fail-fast
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running 2 tests
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test font::encoding::tests::test_differences_overlay_skips_notdef ... ok
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test font::encoding::tests::test_differences_overlay_skips_notdef_with_slash ... ok
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test result: ok. 2 passed; 0 failed; 0 ignored; 0 measured; 2895 filtered out
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```
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## Related beads
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- `bf-4zgpr`: Added `unmapped_glyph_names` config field to DifferencesOverlay
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- `bf-6cvmz`: Documented unmapped_glyph_names configuration structure
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- `bf-o4nrq`: Documented CMAP entry creation point
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- `bf-1puzp`: Earlier verification of CMAP skip logic
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## CMAP entry creation point
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This implementation is at the CMAP entry creation point identified in child beads:
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- **Marker comment**: Line 222-223 in `encoding.rs`
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- **Context**: Type1 font encoding differences parsing
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- **Call site**: `DifferencesOverlay::parse()` method
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## Conclusion
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All acceptance criteria for this bead were already met by prior work. The implementation correctly skips unmapped glyph names during CMAP generation, preventing them from appearing in text extraction output.
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