Accept dangling pointers and cut parse memory

[DavidMStraub]

Dangling pointers

loads()/load() no longer raise GedcomParseError for a pointer that matches no record. The pointer is kept as written, and validate() reports each one as a dangling-pointer error with its path (e.g. @F1@ FAM > WIFE).

Until now, one broken pointer stopped the whole parse, so a consumer such as gramps-gedcom7 could neither list all broken pointers nor import the rest of the file. Duplicate cross-reference identifiers still raise, because with duplicates the parser cannot tell which record a pointer means.

Behaviour change: code that relied on loads() to reject such files must now call validate().

Memory

• GedcomStructure is a slots=True dataclass.
• Each tag is interned, so all lines with the same tag share one string.
• Lines are read one at a time instead of building a list of every line first.

Measured on a synthetic 35 MB file (100,000 individuals, 1.8M lines):

	Before	After
Peak during parse	627 MB	332 MB
Parsed tree left afterwards	472 MB	328 MB
Time	3.85 s	3.70 s

Behaviour change: because of __slots__, GedcomStructure instances no longer accept attributes beyond their fields, have no __dict__, and cannot be weakly referenced.

Tests

• The test that expected the raise now checks that a dataset with three dangling pointers and one @VOID@ parses, and that validate() reports exactly the three.
• The new line splitter is checked against the old re.split behaviour on every string over a, \r, \n up to length 7.

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[Copilot]

Copilot review overview

🟡 Changes recommended

Validation currently misses dangling pointers on extension and non-pointer-typed structures.

Review effort: Balanced
Findings: 1

Open (1)

• Validate dangling pointers in extensions and misplaced pointer fields · New

What changed in this PR

Updates parsing to preserve dangling pointers while reducing memory usage.

Changes:

• Defers dangling-pointer detection to validation.
• Streams line splitting, interns tags, and slots structures.
• Adds documentation and regression coverage.

File	Description
gedcom7/​parser.py	Reduces parsing allocations and preserves unresolved pointers.
gedcom7/​types.py	Enables dataclass slots.
test/​test_parser.py	Tests line-splitting equivalence.
test/​test_conformance.py	Tests dangling-pointer behavior.
README.md	Documents the behavior change.

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[Copilot]

Copilot review overview

🟢 Approval recommended

The implementation consistently matches the documented behavior and includes focused regression coverage.

Review effort: Balanced
Findings: None

Resolved since last review (1)

• Validate dangling pointers in extensions and misplaced pointer fields