feat: implement rel parsing

[nyurik]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 68.75000% with 35 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/ast/attribute_value_for_relation_type.rs	54.54%	6 Missing and 9 partials ⚠️
src/ast/attribute_definition_for_relation.rs	68.18%	2 Missing and 5 partials ⚠️
src/ast/attribute_value_for_relation.rs	37.50%	0 Missing and 5 partials ⚠️
src/ast/dbc.rs	85.71%	1 Missing and 3 partials ⚠️
src/ast/attribute_default.rs	60.00%	1 Missing and 1 partial ⚠️
src/ast/attribute_definition.rs	87.50%	1 Missing and 1 partial ⚠️

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[Copilot]

Pull Request Overview

This PR implements support for relational attributes in DBC file parsing, which previously resulted in NotImplemented errors. The changes enable parsing of BA_DEF_REL_, BA_DEF_DEF_REL_, and BA_REL_ constructs that define and store attributes for relationships between nodes, messages, and signals.

• Added three new AST types to represent relational attributes and their definitions
• Integrated relational attribute parsing into the main DBC parser
• Updated snapshot tests to reflect successful parsing instead of errors
• Refactored shared parsing logic in AttributeDefinition into a reusable function

Reviewed Changes

Copilot reviewed 17 out of 17 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/ast/mod.rs	Exports new relational attribute modules
src/ast/dbc.rs	Adds fields for relational attributes and integrates parsing logic
src/ast/attribute_definition_for_relation.rs	New module defining AttributeDefinitionForRelation struct
src/ast/attribute_value_for_relation.rs	New module defining AttributeValueForRelation struct
src/ast/attribute_value_for_relation_type.rs	New module defining AttributeValueForRelationType enum
src/ast/attribute_definition.rs	Refactors parsing logic into reusable parse_obj_type_vals function
src/ast/attribute_default.rs	Updates to handle both regular and relational attribute defaults
tests/snapshots/dbc-cantools/*.snap	Updated snapshots showing successful parsing of relational attributes

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[tegimeki]

Looking good so far, it works on some of the trickier private DBCs which use BA_DEF_DEF_REL and other less-common ones (which never worked w/the original crate)!

I'm going to test and read through some more and let others do the same, then am inclined to approve.

Is the codecov percentage for the new changes a concern?

[DanielT]

Looks good to me.
You'll want to make the fields of the new structs pub though.