Structure based navigation and manipulations

[mmontone]

Have commands for navigation and manipulation based on structure.

A possible list:

• Navigation:
  • next-sibling: Move focus to next sibling.
  • prev-sibling: Move focus to previous sibling.
  • move-to-parent: Move focus parent node.
  • move-to-child: Move focus to first child node.
• Manipulations:
  • delete-focused: Deleted currently focused node.
  • kill-focused: Delete and copy currently focused node.
  • swap-with-next: Swap current node with next sibling.
  • swap-with-prev: Swank current node with prev sibling.

The good thing is that these will translate to every mode, not only Lisp mode.

I would like to implement, but I'm finding it a bit difficult for now because I don't fully understand Neomacs model yet (marks/nodes/positions/elements).

Thoughts?

[kchanqvq]

Looks good! Thanks for sharing your thoughts!

The motion commands are mostly mode-agnostic so far.

• next-sibling: we have forward-element, forward-element-end
• prev-sibling: we have backward-element
• move-to-parent, move-to-child: don't have them yet, but should be straightforward to add

I'm able to make them mode-agnostic largely because of selectable-p-aux, which allows modes to define positions that make sense for them. Caveat: one could argue that the above set is not "fully-structural" -- what if a mode has a different idea of abstract node from concrete DOM elements? In practice I found them mostly sufficient, because their behavior can be customized by banning unwanted positions using selectable-p-aux.

Manipulations:

I don't have much them yet, because I once had a hard time figuring out how to make them mode-agnostic (and not breaking invariants that modes respect, while we don't have a schema system yet!). But now I think maybe we can just do the same thing as how I did for motion -- use DOM element as the basic unit. Note that the commands you propose don't change sibling level (i.e. not moving up or down nodes) -- that means if the imaginary schema system only supports "can contains" relation, then these command won't ever break the schema. We still need more thoughts if we want to add commands that move up or down nodes, though.

• delete-focused, kill-focused: we have cut-element, copy-element
• swap-with-prev, swap-with-next: don't have them yet, but doable
• raise-node, descent-node...: how?

[mmontone]

sometimes the commands do nothing.

Does the problem persist? Can you provide a test case?

The problem is fixed. One last thing that my implementation does, is to move the focus . So if I have:

^foo
bar
baz

and swap next:

bar
^foo
baz

and again:

bar
baz
^foo

The focus is kept in foo, like I'm moving it, structurally. Both for next and for previous swaps.

[kchanqvq]

My implementation should does that as well. Did you find a case where it fails?

[mmontone]

I always fails :) Focus never moves, is maintained at same position after the swap.

[mmontone]

Auch. Wait. My implementations are overwriting yours swap-nodes :/

[mmontone]

They work perfectly actually :) It was a name clash with my custom functions.