Kconfig plugin for TraVarT

This repository contains an adaptation of Kfeature as a plugin for TraVarT.

Transformations from the original Kfeature are re-implemented, alongside with completely new transformations:

• Backward transformation from Kconfig to UVL (roundtrip transformation)
• Forward transformation from UVL to Kconfig

This plugin provides an intermediate model format for Kconfig files (KconfigModel), which is based on a directed graph structure (KconfigGraph), the nodes being confsyms (or equivalent blocks, menus, choices...) and the edges being dependencies. KconfigReader is also implemented, which delivers KconfigModels for a given Kconfig file. The node types used in KconfigGraph are implemented with generics and coupled polymorphism. We utilize LogicNG (which is also used by UVL internally) to allow composite dependency expressions, through which we also provide a novel transformation for such expressions into respective UVL constraints. We use mintcoffee's ANTLR3 parser grammar for Kconfig files, which was also used in the original Kfeature implementation, although with few changes (see below).

The round-trip transformer supports following Kconfig structures (KconfigModelTwoWayGraphTransformer with processGraph and processToGraph):

• Choice blocks, tristate and boolean
• Menu blocks
• Tristate and boolean confsyms
• Forward and reverse dependencies (select), regardless of dependee expression

...although with certain caveats:

• The parser grammar for dependee expressions is slightly altered to match with the LogicNG syntax ($false instead of false, | and & instead of || and &&, ~ instead of !)
• Due to typing issues, menuconfig confsyms are reduced to regular boolean confsyms
• modules for reducing tristate confsyms to boolean confsyms is ignored, Kconfig files without a respective modules confsym are processed regardless

Certain transformations are trivial, but not implemented due to parser/time restrictions:

• There is a rudimentary one-way transformation for if blocks, but the backward transformation is missing
• String-, integer- and decimal-valued confsyms (trivial due to UVL allowing arbitrary feature attributes)
• imply and default (or in general, all structs refering to confsym default values)

The partial round-trip transformation (Kconfig -> UVL) is bootstrapped in the one-way transformer. This might produce some redundant attributes (active and hasSelectDep) if unsupported constructs are transformed.

The one-way transformer supports following UVL structures (KconfigModelOneWayGraphTransformer with processToGraph):

• Mandatory and optional features
• Alt and or groups
• Feature model constraints

...although with certain caveats:

• Only simple implication constraints are supported, and these might break the produced model used alongside with or groups
• Only 1..* or groups are supported
• Chains of mandatory features might result in unsatisfiable Kconfig models (depending on the used Kconfig backend)

The code is mostly self-documented. For implementing own unit tests, copy one of the tests in KconfigTest and replace the URI given to KconfigReader with your respective Kconfig file. For testing the one-way UVL to Kconfig transformation, you have to build your UVL feature model by hand (see oneWayOrTest) and compare it with the expected result, using AssertJ. You might have to ignore certain fields, see already implemented tests for pointers.