Apply transactions to all views

[the-mikedavis]

Previously, transactions were only applied to the currently focused view. This could lead to jumplist selections not being updated or panics if a jumplist selection pointed past the end of the document.

Closes #4732
Closes #4600
Closes #4841

[the-mikedavis]

This change looks large but it's mostly borrowing fixes that are necessary because we need to mutably borrow Editor after immutably borrowing Document and/or View.

The upshot is that after this change, we use immutable borrows for Document and View much more often. Plus Document doesn't depend on View anymore.

The real changes in this PR come from moving apply_transaction, undo, redo, earlier, later, restore and reload into Editor

[archseer]

The upshot is that after this change, we use immutable borrows for Document and View much more often.

Well, it's now an immutable borrow followed by a mutable borrow in the apply code.

This is pretty intrusive and will end up updating various jumplists per keypress. What if we did the fixup in the event transition handling? Probably after:

helix/helix-term/src/ui/editor.rs

Lines 1409 to 1422 in 1db01ca

	// if the focused view still exists and wasn't closed
	if cx.editor.tree.contains(focus) {
	let config = cx.editor.config();
	let mode = cx.editor.mode();
	let view = view_mut!(cx.editor, focus);
	let doc = doc_mut!(cx.editor, &view.doc);
	view.ensure_cursor_in_view(doc, config.scrolloff);
	// Store a history state if not in insert mode. This also takes care of
	// committing changes when leaving insert mode.
	if mode != Mode::Insert {
	doc.append_changes_to_history(view.id);
	}

We previously did something like if the focused document changed, do a bunch of logic. I'd track the history revision number on the doc (+ doc_id so we're checking the same doc) before the key is pressed, and after, then apply that set of changes to other views. This way we're only applying changes that are in history (one squashed transaction, and not per keypress in insert mode)

We could also consider something like delaying this application until editor.switch/view focus is changed

[the-mikedavis]

This is much cleaner 👍. We could revert #4186 and #4227 but I left that as a TODO since it would be very noisy in the diff.

[archseer]

Note: mouse clicks can also change view focus and are handled separately further below

[archseer]

Ah ok, this will apply as soon as changes are added to history, I thought it was when focus is changed 👍🏻

[archseer]

❤️