How can I store line numbers for a parsed YAML file in JavaScript?

Question

I'm currently writing a Node.js application that parses a YAML file. Under some situations, I need to be able to retrieve the line number corresponding to a value. For instance, if the YAML was person: username: jsmith password: hunter2 I might want to display the message "Error on line 3: Bad password".

Obviously, this is a trivialized example, but the point is there's nothing wrong with the YAML itself.

I've been using yamljs and was able to add the line number directly to the objects via the Object.defineProperty method, but this does not work for strings, so if we had the following YAML passwords: - aG00dP@ssw0Rd - hunter2 I wouldn't be able to give a line number for "hunter2".

Some of my thoughts:

• Box all values in a { lineNumber, value } object. This seems clunky to me, as I would have to call .value on everything. I would really prefer not to have the line number impact any downstream code that is acting on the object.
• Store a hash of the values with their line numbers. This wouldn't work, because as far as I know I wouldn't be able to tell the difference between duplicate strings (for example, if "hunter2" was included further on in the document)
• Extend String to store the line number, but still act like a string. This seems ideal, but I don't know if it's entirely possible. I've tried my hand at it and none of the approaches have worked for me yet.

Is there another way I haven't thought of? Are any of the approaches I mentioned actually feasible, and I've just been doing it wrong?

Answer 1

For anyone interested, I ended up storing the line number on arrays/objects and foregoing it on strings. It's not ideal, but the costs of trying to solve it in the other ways outweighed the benefits. Plus, my use case will probably see more arrays/objects anyway.

I forked the yamljs repository here: https://github.com/pumlhorse/yaml.js

Edit: I happened upon another question that mentioned adding properties to String and realized that that was a solution to my problems. I modified the repository above to return String objects, as opposed to primitives, and that provided the functionality I needed.