As part of #1405, we changed the way we performed undo and redo to
support combining transactions that were not temporally adjacent for
IME purposes.
We introduced a bug with that release that caused divergence
when performing undo: the bug was caused by only changing the visibility
of fragments whose insertion id was contained in the undo operation. However,
an undo operation also affects deletions which we were mistakenly not
considering. Randomized tests caught this but I guess we didn't run enough
of them.
Now, instead of using these versioned offset ranges, we locate the
fragments associated with a transaction using the transaction's
edit ids. To make this possible, buffers now store a new map called
`insertion_slices`, which lets you look up the ranges of insertions
that were affected by a given edit.
Co-authored-by: Antonio Scandurra <antonio@zed.dev>
* Moving the logic from Rope to text::Buffer makes it easier
to keep the Rope in sync with the fragment tree.
* Removing carriage return characters is lossier, but is much
simpler than incrementally maintaining the invariant that
there are no carriage returns followed by newlines. We may
want to do something smarter in the future.
Co-authored-by: Keith Simmons <keith@zed.dev>
Previously, buffer edits represented empty strings as None
variants of an Option. Now, the edit logic just explicitly
checks for empty strings.
Co-authored-by: Keith Simmons <keith@zed.dev>
This way, completions are dealt with more consistently with code actions,
and the logic is not spread across so many places. The `language::File`
trait and the multibuffer no longer need to deal with completions. Completions
are no longer generic over an anchor type.
This is required because, after joining, we want to be able to refer
to operations that have happened prior to joining, which are not
captured by the state. There is probably a way of reconstructing operations
from the state, but that seems unnecessary and we've already talked about
wanting to have the server store operations rather than state once we start
persisting worktrees.
The main reason for this is that we need to include information about
a buffer's UndoMap into its protobuf representation. But it's a bit
complex to correctly incorporate this information into the current
protobuf representation.
If we want to continue reusing `Buffer::apply_remote_edit` for
incorporating the historical operations, we need to either make
that method capable of incorporating already-undone edits, or
serialize the UndoMap into undo *operations*, so that we can apply
these undo operations after the fact when deserializing. But this is
not trivial, because an UndoOperation requires information about
the full offset ranges that were undone.
Antonio Scandurra