Wondering if there's any interest in this. Here's my current use case:

I need to go through Handlebars templates and extract keys for i18n. Basically, it works like this:

Given this sample template:

{{#t "foo"}}Foo{{/t}}

The extracted keys would be:

{ foo: "Foo" }

So far, Handlebars.parse and friends have been extremely easy to work with.

But, we do have some custom validation rules and being able to give the person running my extractor a line number would be extremely useful.

I'm opening this issue to gauge interest. I'd be happy to take a stab at implementing the pull request if I can figure it out.