Implementing custom rules on Rusty

[jeremyjosephabraham]

Hi all, I am looking to make a static analyzer for Structured Text and I was wondering where in the source code, I could start with implementing custom rules for static analysis passes, I wanted to modify the rule engine/AST and the Parser to implement my own rules on the ST code and then generate warnings based on the said rules
(this is without code generation)

[ghaith]

Hello @jeremyjosephabraham,
validations are in the validation module (src/validation.rs). They depend not on a generated model but on a parsed/indexed/resolved module. The driver will guide you through the procedures. Code generation happens at the end, so it can be ignored. You can usually skip generation using the check sub-command or the --check flag instead of the build sub-command.

As you said you intend to change the AST/parser, could you give us examples on how these modifications would look like?
Are you intending to contribute to the main source or do you want to use rusty as part of another project?
In case you want to use it in another project, RuSTy is built as a library. In general you can just rebuild your driver to do only the steps you need and add your own validators. We have a new AstVisitor that would make it easier to write validation rules. The validation results are reported as a diagnostic. You can use your own error codes, which can be configured to be treated as errors/warnings/ignored by the diagnostician when the compilation is done.
Take a look at the architecture documentation : https://plc-lang.github.io/rusty/arch/architecture.html as well as the error configuration to see how this works: https://plc-lang.github.io/rusty/using_rusty/error_configuration.html
We're happy to help if you have more concrete questions :)

[jeremyjosephabraham]

Thanks a lot! I was also wondering if it was possible to enable Rusty to support the .iecst structured text. It shows in a file called iecst.min.js in the book folder, but is it possible to configure rusty to work with iecst?

[ghaith]

could you elaborate on that? We try to be compatible with the codesys dialect and the norm. i think the iecst version is heavily inspired by codesys. The one in the book is there for basic syntax highlighting, it just defines the grammar.