Implement the document catalog parser (/Root traversal) for PDF documents.
The catalog parser extracts all key entries from the document catalog
including Pages, Outlines, MarkInfo, StructTreeRoot, AcroForm, Names,
Metadata, PageLabels, OCProperties, OpenAction, AA, and Version.
Key structures:
- MarkInfo: parses /MarkInfo dictionary with is_tagged, user_properties, suspects
- PageLabelStyle: enum for all label styles (D, R, r, A, a)
- PageLabel: single page label with style, prefix, and start value
- PageLabelsTree: number tree parser for /PageLabels with /Nums and /Kids support
- OcProperties: stub for OCG implementation (delegated to dedicated bead)
- Catalog: main catalog struct with all required and optional fields
Number tree implementation:
- Parses /Nums arrays (leaf nodes with alternating key-value pairs)
- Supports /Kids arrays (internal nodes for recursive tree traversal)
- Provides get_label_with_start() and get_label() methods for lookup
- Correctly formats roman numerals (uppercase/lowercase) and letter sequences
All 27 tests pass including proptests for fuzzing robustness (INV-8).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Changed Diagnostic::msg from String to Cow<'static, str> to avoid
allocations for static error messages. Static messages now use
Cow::Borrowed, while dynamic formatted messages use Cow::Owned.
Also fixed peek_token lifetime issue - was returning reference to
local variable, now returns reference from cache.
Acceptance criteria:
- Token enum with all required variants
- Lexer struct with position tracking and diagnostics
- Diagnostic uses Cow<'static, str> for zero-allocation static messages
- All public methods implemented: new, next_token, peek_token, position, take_diagnostics
- All internal helpers implemented
Refs: pdftract-4hn1
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Bead-Id: pdftract-4hn1
