pdftract/notes/pdftract-469s.md

pdftract-469s: Implement direct object parser

Summary

This bead implements the core ObjectParser::parse_direct_object() method that handles all PDF direct object variants. The implementation was already present in the codebase; this bead added missing test coverage to ensure correctness.

Work Done

1. Added New Tests

Critical Tests from Plan

• 4-level nested dict test (test_parse_4_level_nested_dict): Verifies << /A << /B << /C << /D 1 >> >> >> >> parses correctly with proper nesting
• Array of mixed types test (test_parse_array_5_elements_mixed_types): Verifies [1 true (str) /Name null] produces correct 5-element array
• Indirect reference test (test_parse_indirect_ref): Already existed, verifies 5 0 R -> PdfObject::Ref(ObjRef{5, 0})

Edge Case Tests

• Depth limit test (test_depth_exceeded_at_256): Verifies that 300-level nested dict triggers STRUCT_DEPTH_EXCEEDED at depth 256, returning PdfNull at that level
• Truncated dict test (test_truncated_dict_at_eof): Verifies << /Type /Catalog /Pages (EOF after key) produces partial dict with 2 keys and diagnostic
• Negative indirect ref test (test_negative_indirect_ref): Verifies invalid negative object numbers are handled

Property-Based Tests

• proptest_random_tokens_no_panic: Random PDF token sequences never panic (INV-8)
• proptest_random_bytes_no_panic: Random byte sequences never panic (INV-8)

2. Files Modified

• crates/pdftract-core/src/parser/object/parser.rs: Added 5 new tests and 2 proptest tests

Acceptance Criteria Status

Criterion	Status	Notes
All direct object variants parse correctly	PASS	Implementation already complete in parser.rs
Nested dict 4 levels deep -> correct tree	PASS	test_parse_4_level_nested_dict
Array of mixed types -> correct 5 elements	PASS	test_parse_array_5_elements_mixed_types
5 0 R -> PdfObject::Ref(ObjRef{5, 0})	PASS	test_parse_indirect_ref (pre-existing)
Truncated dict at EOF -> partial dict + diagnostic	PASS	test_truncated_dict_at_eof
Depth-300 nested dict -> STRUCT_DEPTH_EXCEEDED	PASS	test_depth_exceeded_at_256
proptest: random tokens never panic	PASS	proptest_random_tokens_no_panic
INV-8 maintained	PASS	All error paths use diagnostics, no panics

Test Results

cargo test --lib -p pdftract-core -- parser::object
test result: ok. 49 passed; 0 failed

All tests pass, including:

• 25 parser tests
• 24 type tests
• 2 proptest tests

Implementation Notes

The core parser implementation was already complete in parser.rs:

• parse_direct_object() handles all token types
• parse_integer_or_ref() implements 3-token lookahead for indirect references
• parse_array() handles recursive array parsing with depth limit
• parse_dict() handles dictionary parsing with alternating key-value pairs
• Stream detection and body skipping implemented in parse_dict()
• Depth limit of 256 enforced via MAX_DEPTH constant

References

• Plan section: Phase 1.2 lines 1057-1068
• INV-8: No panics at public boundaries
• Files modified:
  • crates/pdftract-core/src/parser/object/parser.rs