Extend the feature modeling language with XOR, OR grouping and optionality

[Lycheers]

Description

We extended the feature model editor with the following options:

• support xor and or operators for feature relationships
• add ? syntax for optional features
• new operators have a different highlighting than the feature names

We modified the grammar rule in FeatureModel.bnf to enable new operators and then added the definition of new tokens in the FeatureModel.flex. After that, we did the same thing for the FeatureModelHighlightingLexer.flex to allow a distinct coloring. We also need to define the tokens in the class FeatureModelSyntaxHighlighter.java and include cases when xor, or and ? are detected. Lastly, we have to change a minor part in FeatureModelAnnotator.java to disable the enforced feature coloring.

Related Issue

#42

Motivation and Context

Feature models in Clafer require support for grouping operators to match the language specification. With more boolean operators enabled, we are allowed to do more designs in the feature models. These changes improve usability and compliance with Clafer’s feature modeling semantics.

How Has This Been Tested?

• Tests are created and passing
• Manual testing
  We included the operators xor, or and ? into the given feature-model file in the Snake project and checked if errors occur. We also wrote a small test to check if xor, or and ? are really recognized as our defined tokens.

Demo:

Cross-Tree.dependency_demo.mp4

Types of changes

• Pipeline changes
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
  • I have updated the documentation accordingly.
• I have updated the CONTRIBUTORS file.
• I have updated the CHANGELOG.