Struct ActiveDocument 

pub struct ActiveDocument(/* private fields */);

M.0 (2026-05-31): the active-document slot held by Editor.document. Wraps an Arc<dyn Document> so that:

• The slot can hold either a regular rope-backed handle (today: RopeDocumentHandle, renamed to RopeDocumentHandle in M.0 Phase E) or a MultibufferDocumentHandle (M.1) without kind-branching at the use site — dispatch / motion / render code paths just call Document trait methods through Deref<Target = dyn Document>.

• The slot impls Default (initialised to a placeholder rope handle via RopeDocumentHandle::default()) so consumers that #[derive(Default)] over a struct containing this field work without hand-rolling the impl. The placeholder’s actor receiver is closed immediately at construction, so any traffic sent through the placeholder reports RuntimeError::ActorGone — production code overwrites the slot before any real traffic flows.

• The newtype is cheap to clone (one atomic refcount bump on the inner Arc).

Arc<dyn Document> directly cannot implement Default (orphan rule on Arc + dyn Trait: !Sized), so this newtype is the smallest viable wrapper that keeps the derive ergonomics intact without forcing a manual impl Default over every struct that holds the slot.

Implementations

impl ActiveDocument

pub fn new<D: Document>(handle: D) -> Self

Wrap a concrete document handle. The handle must impl Document (today: RopeDocumentHandle / future RopeDocumentHandle; M.1: MultibufferDocumentHandle).

pub fn from_arc(arc: Arc<dyn Document>) -> Self

Wrap an already-Arc’d handle. Useful when an Arc<dyn Document> is constructed elsewhere (e.g., by the buffer registry) and the slot just takes ownership of it.

pub fn as_arc(&self) -> Arc<dyn Document>

Cheap clone of the inner Arc. Use when handing the reference off to a long-lived consumer that wants to store it independently.

Trait Implementations

impl Clone for ActiveDocument

fn clone(&self) -> ActiveDocument

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ActiveDocument

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for ActiveDocument

fn default() -> Self

Returns the “default value” for a type.

impl Deref for ActiveDocument

type Target = dyn Document

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.