Consider using RegExp and CPM instead of a Babel transform #15

I recently watched (and enjoyed!) @serenaf's talk about this addon at EmberCamp London 2016.

I had an idea for how this might be doable without having to resort to a Babel transform (which I had a few concerns about) while still maintaining the same interface. I gave it a shot and was able to get this to work using a computed property macro and a RegExp.

The idea behind my approach relies on three observations:

• We can use a regular expression to find all the properties/paths in the template string
• The String.prototype.replace function supports having a function passed as a second parameter which lets you dynamically replace a match based on the contents of the match
• Computed property macros can be generated with dynamic keys based on the passed value

The approach is then to create a computed property macro which:

• Constructs and uses a regular expression to get all properties/paths in the passed template string, then
• Uses those properties (after a uniq to avoid duplication) as the dependent keys of the generated computed property, and finally
• Uses String.prototype.replace to replace instances of ${property} with the get() lookup of those properties.

You can see my solution in a twiddle (source). For the tests I copied the tests in this project's tests/unit/custom-replace-call-paths-test.js, and they seem to all pass.