Finding unused classes

[lukepighetti]

I'm just poking around with dart_codemod and I was wondering if someone would be willing to suggest/discuss a strategy for finding unused classes.

My idea was to visit every class declaration and get the name of the class, then search the rest of the AST for any use of the constructor. I tried to walk the tree and wasn't successful.

void main(List<String> arguments) {
  runInteractiveCodemod(
    filePathsFromGlob(Glob('**.dart', recursive: true)),
    PrintEveryCommentInProject(),
    args: arguments,
  );
}

class PrintEveryCommentInProject extends GeneralizingAstVisitor
    with AstVisitingSuggestorMixin {
  @override
  dynamic visitDeclaration(Declaration node) {
    print(node.documentationComment);

    node.visitChildren(this);
  }
}

[evanweible-wf]

Hi @lukepighetti! I think you'd need a fully resolved AST (or maybe an ElementVisitor) so that you can determine where each class is located in addition to its name, otherwise you could have classes that are distinct but named the same.

Either way, I'd probably start by writing a visitor that implements visitClassDeclaration to collect all of the classes, and then pass that info to another visitor that implements visitTypeName to determine which classes are unused. I haven't tested that idea, so there might be another visit method that would be better.. I can never quite keep all the analyzer APIs straight in my head :)

Couple other things to keep in mind:

• Any class that is publicly exported from a package is technically "used" even if it doesn't have any usages in its own package.
• Depending on what you want to do once you've found the unused classes, you might not even need this package - you might be able to get by with just package:analyzer

Hopefully that helps!