How to evaluate syntactical correctness of EPL patterns

[folmate]

Hi,
I have been trying to create a small code for filtering out syntactically incorrectness of epsilon patterns, however, the parser seems to either ignore errors, like undefined variables, or flagging attributes as erroneous.

My question is: How to configure a standalone EPL module to check if a pattern is syntactically correct without an instance model?

var module = new EplModule();
module.parse("""
pattern GoRoute
    route: Route from : Route.all.select(rt | rt.entry.signal == Signal#GO) {
    
    match: (route.active) and 
        route.follows->exists(swP | swP.position != swP.target.currentPosition)
}
"""); // Point (1) (Yes, this is a correct one, but easy to break.)
var instance = new InMemoryEmfModel(makeEmpty()); // placeholder empty resource set
module.getContext().getModelRepository().addModel(instance);
var results = (PatternMatchModel) module.execute(); // Point (2)

At (1), 'active' is (erroneously) flagged for no viable input, but it still gives correct results when executed.

At (2), if there is a model that somewhat resembles the pattern, then some errors are detected, like undefined variables, but without an instance model, the problems are just ignored. (Metamodel is available in the form of an EPackage and registered to the global epackage registry.)

[kolovos]

active is a keyword in EPL, which is why you get the no viable input error message. To fix this you'd need to escape active using backticks (i.e. route.`active`). When you call module.parse() the expectation is that you then check for the presence of parse errors using module.getParseProblems() before you attempt to execute the module. If you don't do this and execute a module that has parse errors, you may run into unexpected behaviour.

Regarding the second issue you are describing, essentially you are looking for a static analyser for EPL. We're working on a static analyser for Epsilon in https://github.com/epsilonlabs/epsilon-with-lsp/ but it doesn't cover EPL yet.

[folmate]

Thanks for the response. I have two follow-up questions.

(1) Is it possible to access the internal representation of the parsed pattern and traverse it somehow? (I'm thinking throwing something together to have some simple checks.)

(2) Can you give rough estimate on the timeline on the static analyser?

[kolovos]

(1) Is it possible to access the internal representation of the parsed pattern and traverse it somehow? (I'm thinking throwing something together to have some simple checks.)

Sure - please see https://eclipse.dev/epsilon/doc/articles/run-epsilon-from-java/#analysing-epsilon-programs

(2) Can you give rough estimate on the timeline on the static analyser?

A conservative estimate for the EPL static analyser would be the the end of the year.