[refactor] namespace parent member expression validation into separate helper function

[azyzz228]

Two slowest rules namespace and no-deprecated used almost same lines of code for validating member expressions. I refactored validation function into separate helper function namespaceValidator. Then, I changed namespace and no-deprecated to use namespaceValidator function.

[ljharb]

hm, do we need these early returns?

[azyzz228]

I re-produced exact flow as in namespace rules: https://github.com/import-js/eslint-plugin-import/blob/main/src/rules/namespace.js. Lines 124-140.

Line 139 of original namespace rule has break instead of return, but because nothing comes after while loop, break does the same thing as return?

[ljharb]

Are there any cases of calling onNamespaceNotFound where we don't want to break/return?

[azyzz228]

Yes. onNamespaceNotFound is only used in namespace rule.

If we can find node's name in namespace map, then but just proceed execution. We only return/break when we cannot find node's name in namespace map.

Below is onNamespaceNotFound in namespace rule, we pass what's below to our helper function.

        function onNamespaceNotFound(context) {
          return function inner(node, namespace, namepath) {
            if (!namespace.has(node.property.name)) {
              context.report(
                node.property,
                makeMessage(node.property, namepath),
              );
              return 'return';
            }
          };
        }

[ljharb]

gotcha, hmm.

not a fan of returning the string "return", maybe it could be a true or something, but returning a sentinel value seems to be the only solution.

ahhhh wait! what if the inner callback took a fourth argument, that meant "return", for it to return? that way "what kind of value if is" is up to the helper implementation

[azyzz228]

That's brilliant! I implemented it here: azyzz228@5985656. Because no-deprecated rule for now just skips computed, meanwhile namespace one works through it and takes in node as an argument, I used arguments[2] in no-deprecated's onComputed to communicate return to namespaceValidator

[ljharb]

@azyzz228 this PR will need a rebase, and unfortunately it doesn't seem trivial.