cb966dfdef
All components verified: - types.rs: PdfObject enum, ObjRef, PdfDict (IndexMap), PdfStream - cache.rs: LRU 4096 entry cache with cycle detection - cycle.rs: Per-thread resolution stack - parser.rs: Direct and indirect object parsing - objstm.rs: Object stream parser with /Extends support Critical tests pass (99 total): - Nested dict: test_parse_nested_dict, test_parse_4_level_nested_dict - Array of mixed types: test_parse_mixed_array, test_parse_array_5_elements_mixed_types - Object stream: test_parse_simple_objstm, test_parse_objstm_10_objects - Self-referencing: test_cycle_detection, test_depth_limit - INV-8 (no panic): proptest_random_bytes_no_panic, proptest_random_tokens_no_panic Closes pdftract-54pt
92 lines
4.4 KiB
Markdown
92 lines
4.4 KiB
Markdown
# Verification Note for pdftract-54pt
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## Phase 1.2: Object Parser — Verification Summary
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### Date
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2026-06-02
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### Scope
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The Object Parser consumes the Lexer's token stream and produces the in-memory PDF object model. It handles indirect-object wrappers, object streams (/ObjStm), and the per-thread cycle-detection stack that prevents STRUCT_CIRCULAR_REF from causing stack overflow during dereferencing.
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### Components Verified
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#### 1. Types Module (crates/pdftract-core/src/parser/object/types.rs)
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- **PdfObject enum**: All variants implemented (Null, Bool, Integer, Real, String, Name, Array, Dict, Ref, Stream, Indirect)
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- **ObjRef**: 32-bit object number + 16-bit generation number
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- **PdfDict**: IndexMap-backed (preserves insertion order) ✓
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- **PdfStream**: { dict: PdfDict, offset: u64, len_hint: Option<u64> }
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- **PdfIndirect**: { id: ObjRef, obj: PdfObject }
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- **intern() function**: Thread-local name interner for deduplication
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#### 2. Cache Module (crates/pdftract-core/src/parser/object/cache.rs)
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- **LruCache**: 4096 entry capacity per document
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- **CacheResolutionGuard**: RAII guard for cycle detection + depth tracking
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- **begin_resolution()**: Checks cycles, enforces depth limit (256 levels)
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- **Thread-local depth tracking**: Per-thread counter for concurrent page processing
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- **Statistics**: hit/miss tracking for diagnostics
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#### 3. Cycle Module (crates/pdftract-core/src/parser/object/cycle.rs)
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- **RESOLVING thread-local**: HashSet<ObjRef> per thread
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- **ResolutionGuard**: RAII guard that inserts on creation, removes on drop
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- **is_resolving()**: Cycle detection helper
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- **Panic safety**: Guard cleans up even on panic
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#### 4. Parser Module (crates/pdftract-core/src/parser/object/parser.rs)
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- **ObjectParser::new()**: Creates parser from byte slice
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- **parse_direct_object()**: Parses all PDF object variants
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- **parse_indirect_object()**: Parses N G obj ... endobj wrapper
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- **Depth limiting**: MAX_DEPTH = 256 for arrays/dicts
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- **Error recovery**: Scans forward on malformed input
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#### 5. Object Stream Module (crates/pdftract-core/src/parser/objstm.rs)
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- **ObjectStmParser**: Parses /ObjStm streams
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- **decompress + parse**: Decompresses once, parses all N embedded objects
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- **Cache**: Arc<Vec<(u32, PdfObject)>> for indexed access
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- **/Extends chain**: Cycle detection + depth limit (16 levels)
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- **get_object()**: API for xref type-2 entry resolution
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### Critical Tests Verified
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All tests pass (83 object parser tests + 16 object stream tests = 99 tests):
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1. ✓ **Nested dict**: `test_parse_nested_dict`, `test_parse_4_level_nested_dict`
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2. ✓ **Array of mixed types**: `test_parse_mixed_array`, `test_parse_array_5_elements_mixed_types`
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3. ✓ **Object stream**: `test_parse_simple_objstm`, `test_parse_objstm_10_objects`
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4. ✓ **Self-referencing object**: `test_cycle_detection`, `test_depth_limit`, `test_cycle_detection_fails_on_cycle`
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5. ✓ **INV-8 (no panic)**: `proptest_random_bytes_no_panic`, `proptest_random_tokens_no_panic`
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### Test Results
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```
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PASS [ 0.020s] 83 tests run: 83 passed (parser::object)
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PASS [ 0.020s] 16 tests run: 16 passed (parser::objstm)
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```
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### INV-8 Compliance
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- No panics on any input verified via proptest
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- Proptest harness: random byte sequences and PDF token sequences
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- Depth limits prevent stack overflow (256 for objects, 16 for /Extends)
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### Module Location
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✓ `crates/pdftract-core/src/parser/object/`
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### Public API
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- `ObjectParser::new(bytes: &[u8]) -> Self`
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- `parse_direct_object(&mut self) -> Option<PdfObject>`
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- `parse_indirect_object(&mut self) -> Option<PdfIndirect>`
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- `position(&self) -> u64`
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- `take_diagnostics(&mut self) -> Vec<Diagnostic>`
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### Note on resolve() Method
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The acceptance criteria mentions `resolve(ref: ObjRef) -> Arc<PdfObject>`. This method is implemented in `XrefResolver` (Phase 1.3) because resolving requires the cross-reference table, which is not available during Phase 1.2 parsing. The ObjectParser correctly delegates resolution to the xref layer.
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### Child Beads
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All child beads are implicitly closed as their implementations are complete:
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1. ✓ PdfObject enum + ObjRef type + IndexMap-backed PdfDict
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2. ✓ Indirect object parser (N G obj ... endobj)
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3. ✓ Object stream parser (/ObjStm)
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4. ✓ Cycle detection via per-thread resolution stack
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5. ✓ Object cache (LRU 4096 entries)
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6. ✓ Critical-test fixture corpus + proptest harness
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### Conclusion
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Phase 1.2 Object Parser is fully implemented and all critical tests pass. The codebase is ready for this bead to be closed.
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