805c47b8ff
All 7 sub-components implemented: - Traditional xref table parser - Xref stream parser (PDF 1.5+) - Hybrid file merger - Forward scan fallback - Incremental update chain handler - Linearized PDF support - Comprehensive test corpus (90 tests pass) Acceptance criteria met: - All Critical tests from plan Section 1.3 pass - INV-8 maintained (no panic, verified by proptests) - Module at crates/pdftract-core/src/parser/xref.rs - Test fixtures for linearized, multipage, and minimal PDFs
112 lines
4.5 KiB
Markdown
112 lines
4.5 KiB
Markdown
# Verification Note: pdftract-4m8u
|
|
## Phase 1.3: Cross-Reference Resolution
|
|
|
|
### Date
|
|
2026-06-02
|
|
|
|
### Summary
|
|
All 7 sub-components of Phase 1.3 Cross-Reference Resolution have been implemented and tested.
|
|
|
|
### Implementation Status
|
|
|
|
#### 1. Traditional Xref Table Parser ✅
|
|
- **Function**: `parse_traditional_xref()` in `crates/pdftract-core/src/parser/xref.rs`
|
|
- **Features**:
|
|
- 20-byte fixed-width entry parsing
|
|
- Handles both `\r\n` and ` \n` line endings (19-byte buggy producer support)
|
|
- Multi-subsection table support
|
|
- Trailer dictionary parsing
|
|
|
|
#### 2. Xref Stream Parser ✅
|
|
- **Function**: `parse_xref_stream()` in `crates/pdftract-core/src/parser/xref.rs`
|
|
- **Features**:
|
|
- PDF 1.5+ xref stream format
|
|
- `/W` field width parsing (type_w, obj_w, gen_w)
|
|
- FlateDecode decompression
|
|
- Type-0 (free), Type-1 (in-use), Type-2 (compressed) entry support
|
|
- `/Index` subsection parsing
|
|
- Predictor support (PNG Up predictor)
|
|
|
|
#### 3. Hybrid File Merger ✅
|
|
- **Function**: `merge_hybrid()` in `crates/pdftract-core/src/parser/xref.rs`
|
|
- **Features**:
|
|
- Traditional table + xref stream merging
|
|
- Traditional entries authoritative (override stream)
|
|
- Type-2 entries from stream fill gaps
|
|
- `STRUCT_HYBRID_CONFLICT` diagnostics for conflicts
|
|
|
|
#### 4. Forward Scan Fallback ✅
|
|
- **Function**: `forward_scan_xref()` in `crates/pdftract-core/src/parser/xref.rs`
|
|
- **Features**:
|
|
- Sequential `N G obj` pattern search
|
|
- SIMD-accelerated via `memchr`
|
|
- O(file_size) time complexity
|
|
- `XREF_REPAIRED` diagnostic emission
|
|
- Disabled for linearized files
|
|
- Disabled for remote sources (coordinates with Phase 1.8)
|
|
|
|
#### 5. Incremental Update Chain Handler ✅
|
|
- **Function**: `load_xref_with_prev_chain()` in `crates/pdftract-core/src/parser/xref.rs`
|
|
- **Features**:
|
|
- Recursive `/Prev` chain traversal
|
|
- Later revisions override earlier ones (last-write-wins)
|
|
- Cycle detection via `HashSet<u64>` of visited offsets
|
|
- Depth limit: 32 revisions max (`STRUCT_DEPTH_EXCEEDED` on overflow)
|
|
- Invalid `/Prev` offset handling
|
|
|
|
#### 6. Linearized PDF Support ✅
|
|
- **Functions**:
|
|
- `detect_linearization()` - Detects `/Linearized` dict
|
|
- `load_xref_linearized()` - Loads and merges first-page + full xrefs
|
|
- `merge_linearized_xrefs()` - Merges with full xref priority
|
|
- **Features**:
|
|
- First-page xref + full xref merge
|
|
- Full xref authoritative for overlapping objects
|
|
- Forward scan disabled for linearized files
|
|
- Hint stream offset/length extraction (optional)
|
|
|
|
### Test Results
|
|
|
|
**All 90 xref tests PASS** (verified with `cargo nextest run -p pdftract-core --lib xref`)
|
|
|
|
#### Critical Tests (from plan Section 1.3)
|
|
- ✅ `test_prev_chain_three_revisions_latest_wins` - PDF with /Prev chain of 3 revisions
|
|
- ✅ `test_parse_xref_stream_type2_compressed` - Type-2 xref entry resolved through ObjStm
|
|
- ✅ `test_merge_hybrid_traditional_priority` - Hybrid file traditional entries override stream
|
|
- ✅ `test_forward_scan_truncated_file` - File truncated after xref, forward scan finds objects
|
|
- ✅ Forward scan `XREF_REPAIRED` diagnostic - Covered by `test_forward_scan_simple` and others
|
|
|
|
#### INV-8 Verification (No Panic)
|
|
- ✅ Proptest: `proptest_random_bytes_no_panic`
|
|
- ✅ Proptest: `proptest_random_offset_no_panic`
|
|
- ✅ Proptest: `proptest_forward_scan_no_panic`
|
|
- ✅ Proptest: `proptest_forward_scan_linearized_no_panic`
|
|
- ✅ Proptest: `proptest_parse_xref_stream_no_panic`
|
|
- ✅ Proptest: `proptest_parse_xref_stream_random_offset_no_panic`
|
|
- ✅ Proptest: `proptest_merge_hybrid_no_panic`
|
|
- ✅ Proptest: `prop_prev_chain_random_offsets_no_panic`
|
|
|
|
### Module Location
|
|
✅ `crates/pdftract-core/src/parser/xref.rs` (not a submodule, as per existing codebase structure)
|
|
|
|
### Test Fixtures
|
|
- `crates/pdftract-core/tests/fixtures/linearized-10.pdf` - Linearized PDF test
|
|
- `crates/pdftract-core/tests/fixtures/multipage-100.pdf` - Multi-page test
|
|
- `crates/pdftract-core/tests/fixtures/test-minimal.pdf` - Minimal test
|
|
- `crates/pdftract-core/tests/fixtures/valid-minimal.pdf` - Valid minimal test
|
|
|
|
### Acceptance Criteria Status
|
|
- ✅ All 7 child beads (sub-tasks) implemented
|
|
- ✅ All Critical tests from plan Section 1.3 pass
|
|
- ✅ Linearized fixture tests pass
|
|
- ✅ All xref resolution paths INV-8 maintained (no panic)
|
|
- ✅ Module under `crates/pdftract-core/src/parser/xref.rs`
|
|
|
|
### Code Quality
|
|
- Clean, well-documented code
|
|
- Comprehensive test coverage (90 tests)
|
|
- Proper error handling with diagnostics
|
|
- No compiler warnings specific to xref code
|
|
|
|
### Commits
|
|
Implementation already exists in the codebase (no new commits needed for this bead).
|