Events record indicating the names and types of events emitted by this Collab.
Initializes this Collab with the given InitToken.
The InitToken must have provided by our parent explicitly for this constructor call.
Typically, a Collab subclass takes init as its first constructor
argument and calls super(init).
Internal (this/parent) use only.
This Collab's name, which distinguishes it among its siblings in the tree of Collabs.
Internal (this/parent) use only.
This Collab's parent in the tree of Collabs.
The ambient IRuntime.
Use this to access utilities like IRuntime.replicaID.
Internal (parent) use only.
If this Collab is in its initial, post-constructor state, then this method may (but is not required to) return true; otherwise, it returns false.
By default, this method always returns false; override to change.
If this method returns true:
load(null, meta).
load should process this as if called with the output of save
from a garbage-collectable state. For a nontrivial example,
see [[CMultiValueMap.load]]'s implementation.Emits an event, which triggers all the registered event handlers.
See CollabEventsRecord for advice on what events to emit.
This is a wrapper around EventEmitter.emit that forces events to extend CollabEvent and also emits an "Any" event.
Set to true to skip emitting an "Any" event.
Internal (parent) use only.
Called by this Collab's parent when it has been deleted from a collection on the local replica and can no longer be used (e.g., due to CSet.delete on this or an ancestor). A Collab implementation can implement this method to clean up external resources, e.g., associated DOM elements.
finalize has no relation to the JavaScript garbage collector or
canGC.
By default, this method does nothing.
Internal (parent) use only.
Called by this Collab's parent to load saved state. You may assume that the saved state was generated by save on some replica of this Collab, possibly in a different collaboration session, with guarantees set by the runtime.
This method may also be called with savedStateTree = null;
you should ignore such calls (i.e., return immediately)
unless you override canGC. If you do override canGC,
see that method's docs for instructions.
The saved state to load, in the same format as in save,
or null as described above.
Metadata attached to this saved state by the runtime.
It incorporates all possible metadata requests. Note that
meta.updateType is always "savedState".
Registers an event handler that is triggered when the event happens.
Name of the event to listen on.
Callback that handles the event.
If true, the event handler is triggered at most once (the next time the event happens), then unsubscribed.
An "off" function that removes the event handler when called.
Registers an event handler that is triggered when the event happens.
An "off" function that removes the event handler when called.
Internal (parent) use only.
Receives a message sent by send on a local or remote replica of this Collab.
This method processes the message, changes the local state accordingly, and emits events describing the local changes.
This method should make assumptions and ensure consistency guarantees appropriate to its use case. For example, CRDTs may assume eventual, exactly-once, causal-order message delivery, and they must ensure strong eventual consistency.
The message to receive, in the same format
as in send. This method may mutate messageStack
in-place (e.g., calling pop).
Internal (parent) use only.
Returns saved state describing the current state of this Collab.
The saved state may later be passed to load on a replica of this Collab, possibly in a different collaboration session, with rules set by the runtime. For example, CRuntime allows load at any time; it must then act as a merge operation (like a state-based CRDT), applying all updates that the saved replica had applied before saving, ignoring duplicates.
save may be called at any time, possibly many times while an app
is running. Calling save should not affect this Collab's
user-visible state.
For convenience, the saved state may be expressed as a tree of Uint8Arrays instead of just a single Uint8Array; see [[SaveStateTree]]'s docs.
The saved state.
Broadcasts a message to other replicas of this Collab. The message will be delivered to all replicas' receive, including locally.
For convenience, the message may be expressed as a stack of
(Uint8Array | string),
instead of just a single Uint8Array. This is
useful for parents sending messages on behalf of their children;
see the implementation of CObject for an example.
The message to send, in the form of a stack of Uint8Arrays. Note that this method may mutate it in-place.
A stack of metadata requests. The runtime will use
the union of these when creating the MessageMeta for receive.
Note that the stack need not align with messageStack, and this method may mutate
it in place.
Generated using TypeDoc
Base class for a collaborative data structure (abbreviated "Collab").
A Collab is a data structure that is replicated across multiple devices and stays in sync between them: when one device changes a Collab, their changes show up for every other device.
Like local (non-collaborative) data structures, library users interact with Collabs through type-specific methods (both mutators and accessors). In addition, a Collab emits events describe state changes, in the style of reactive programming. This allows you to observe changes due to remove operations, although local operations also cause events. See on.
This base class provides a framework for implementing and networking Collabs. Most of its properties are not relevant to users of the Collab but are public for technical reasons; these are marked "Internal use only".
To implement a custom Collab, you will usually extend one of the following classes instead of Collab itself: