introduce a `Point` model

Do you want to request a feature or report a bug?

Improvement.

What’s the current behavior?

Right now ranges have properties that represent their two points:

anchorKey
anchorOffset
focusKey
focusOffset

This is alright, but this idea of a “point” is only inferred. There are already places in the codebase that refer to “points” informally, like in the findPoint utility. And we’ve thought about adding even more of them.

What’s the new behavior?

We’d introduce a new model called a Point:

Point {
  key
  offset
}

And ranges would just have two points, range.anchor and range.focus.

This would standardize the data structure, making it easier to use in some cases since we can provide the utility functions on the Point model directly, and make it more of a known entity for userland code to build with.

[zhujinxuan]

@ianstormtaylor I will use anchorPoint and focusPoint as the first step. If they are working, then I will try to rename them and move range.focus to value in the same PR.

[ianstormtaylor]

@zhujinxuan ah good point. I think I’d like to deprecate the .focus()/.blur() methods (on Range, not on Change) and rename them to something like .setIsFocused(boolean) instead. Or even just remove them in favor of using .set('isFocused', true) from Immutable.js honestly.

(This follows with a separate idea I have that ranges themselves shouldn’t even be where the “focused” state lives, since they are lower level than that, but that’s a discussion for another time.)