Feature: move internal node nesting model to doubly linked lists

Today, Lexical nodes are nested using arrays. This means that ElementNode references an array of child node keys. However, we can improve performance by switching away from arrays, and to using doubly linked lists. This would mean

• We remove ElementNode.__children
• We add ElementNode.__first, which is either NodeKey or null.
• We add ElementNode.__last, which is either NodeKey or null.
• We add ElementNode.__size, which is number. Avoiding the need to do O(n) lookups to find the amount of children in the element.
• We add LexicalNode._prev, which is either NodeKey or null.
• We add LexicalNode._next, which is either NodeKey or null.

When we add/remove a node, we’ll need to make sure to update the linked list of both adjacent siblings (__prev and __next). Additionally, if the node is the first or last node of its parent, we’ll also have to update the parent __size, __first and/or __last. We can remove the logic we have for marking siblings dirty, as we’ll do that organically from using linked lists.

[trueadm]

I think we probably want to introduce this to start with, in addition to the existing API. Have them both there, then switch, then remove the old in v0.3. So we’ll be duplicating work for a short-time, to ensure backwards compatibility.

[acywatson]

delete is a method of LexicalNode or ElementNode? Could you tell me where in the code it is? I’m not seeing it

It’s actually called “remove”

https://github.com/facebook/lexical/pull/2044/files#diff-eae9d8a8a05fee2910d2082d36f6f1683ba3632596e8d9cab326ef1fb0651065R660