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Class CValueSet<T>

A collaborative set with values of type T.

The API is compatible* with Set<T> and can be used as a drop-in collaborative replacement when T is internally immutable. If multiple users add and delete the same value concurrently, the add "wins" (the value is present).

Values must be internally immutable; mutating a value internally will not change it on other replicas. If you need to mutate values internally, instead use a CSet.

(*) Except for the return value of add, which is the added value instead of this.

Type Parameters

  • T

    The value type.

Hierarchy

Index

Constructors

Properties

children: Map<string, Collab<CollabEventsRecord>>

The children (registered Collab properties), keyed by name.

This map should only be read, not mutated. It is exposed to subclasses as a convenience for methods that loop over all children.

name: string

Internal (this/parent) use only.

This Collab's name, which distinguishes it among its siblings in the tree of Collabs.

parent: Parent

Internal (this/parent) use only.

This Collab's parent in the tree of Collabs.

runtime: IRuntime

The ambient IRuntime.

Use this to access utilities like IRuntime.replicaID.

Accessors

  • get size(): number
  • The number of values in the set.

    Returns number

Methods

  • [iterator](): IterableIterator<T>
  • Returns an iterator for values in the set.

    The iteration order is NOT eventually consistent: it may differ on replicas with the same state.

    Returns IterableIterator<T>

  • add(value: T): T
  • Adds the value, making it present in this set.

    Parameters

    • value: T

    Returns T

    value.

  • canGC(): boolean
  • Internal (parent) use only.

    By default, this method returns true if canGC returns true on every child. Override to change this behavior.

    See Collab.canGC.

    Returns boolean

  • clear(): void
  • Deletes every value in the set.

    Returns void

  • delete(value: T): boolean
  • Deletes the given value, making it no longer present in this set.

    Parameters

    • value: T

    Returns boolean

    true if value was present and has been removed.

  • 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.

    Type Parameters

    Parameters

    • eventName: K
    • event: SetEventsRecord<T>[K] & CollabEvent
    • Optional options: { skipAnyEvent?: boolean }
      • Optional skipAnyEvent?: boolean

        Set to true to skip emitting an "Any" event.

    Returns void

  • finalize(): void
  • Internal (parent) use only.

    By default, this methods calls finalize on every child. Override to change this behavior, e.g., to add your own finalization steps (but consider calling super.finalize()).

    Returns void

  • forEach(callbackfn: ((value: T, value2: T, set: CValueSet<T>) => void), thisArg?: any): void
  • Executes a provided function once for each value in the set, in the same order as values.

    Parameters

    • callbackfn: ((value: T, value2: T, set: CValueSet<T>) => void)
        • (value: T, value2: T, set: CValueSet<T>): void
        • Parameters

          Returns void

    • Optional thisArg: any

    Returns void

  • fromID<C>(id: CollabID<C>, startIndex?: number): undefined | C
  • Inverse of idOf.

    Specifically, given a CollabID returned by idOf on some replica of this parent, returns this replica's copy of the original descendant. If that descendant does not exist (e.g., it was deleted or it is not present in this program version), returns undefined.

    Type Parameters

    Parameters

    • id: CollabID<C>
    • Optional startIndex: number

    Returns undefined | C

  • has(value: T): boolean
  • Returns whether value is present in the set.

    Parameters

    • value: T

    Returns boolean

  • Returns a CollabID for the given strict descendant of this parent.

    The CollabID may be passed to fromID on any replica of this parent (but not other parents) to obtain that replica's copy of descendant.

    Type Parameters

    Parameters

    • descendant: C

    Returns CollabID<C>

  • Internal (parent) use only.

    Called by this Collab's parent to load saved state. See Collab.load.

    A CObject subclass may override this method to load additional state from Collab.save or to perform extra setup - e.g., refreshing functional views that were not automatically updated by children's load events. It is recommended to do so as follows:

    load(savedStateTree: SavedStateTree | null, meta: SavedStateMeta) {
    super.load(savedStateTree, meta);
    // Process your extra saved state from savedStateTree.self.
    const savedState = savedStateTree === null? null: savedStateTree.self!;
    ...
    // Perform extra setup as needed.
    ...
    }

    Parameters

    Returns void

  • on<K>(eventName: K, handler: ((event: SetEventsRecord<T>[K], caller: CValueSet<T>) => void), options?: { once?: boolean }): (() => void)
  • Registers an event handler that is triggered when the event happens.

    Type Parameters

    Parameters

    • eventName: K

      Name of the event to listen on.

    • handler: ((event: SetEventsRecord<T>[K], caller: CValueSet<T>) => void)

      Callback that handles the event.

    • Optional options: { once?: boolean }
      • Optional once?: boolean

        If true, the event handler is triggered at most once (the next time the event happens), then unsubscribed.

    Returns (() => void)

    An "off" function that removes the event handler when called.

      • (): void
      • Registers an event handler that is triggered when the event happens.

        Returns void

        An "off" function that removes the event handler when called.

  • receive(messageStack: (string | Uint8Array)[], meta: MessageMeta): void
  • 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.

    Parameters

    Returns void

  • registerCollab<C>(name: string, collabCallback: ((init: InitToken) => C)): C
  • Registers a Collab property of this CObject with the given name, making it one of our children.

    Typically, you will call this method during the constructor in the style:

    this.foo = this.registerCollab("foo", (init) => new FooClass(init, constructor args...));
    

    where readonly foo: FooClass; is a Collab property. See Data Modeling for examples.

    Registrations must be identical across all replicas.

    See also: CRuntime.registerCollab.

    Type Parameters

    Parameters

    • name: string

      A name for this property, unique among this class's registerCollab calls. We recommend using the same name as the property, but you can also use short strings to reduce network usage ("", "0", "1", ...).

    • collabCallback: ((init: InitToken) => C)

      A callback that uses the given InitToken to construct the registered Collab.

    Returns C

    The registered Collab.

  • Internal (parent) use only.

    Returns saved state describing the current state of this CObject. See Collab.save.

    A CObject subclass may override this method to save additional state. It is recommended to do so as follows:

    save() {
    const ans = super.save();
    // Put your extra saved state in ans.self, which is otherwise unused.
    ans.self = <subclass's saved state>;
    return ans;
    }

    Returns SavedStateTree

  • send(messageStack: (string | Uint8Array)[], metaRequests: MetaRequest[]): void
  • 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.

    Parameters

    • messageStack: (string | Uint8Array)[]

      The message to send, in the form of a stack of Uint8Arrays. Note that this method may mutate it in-place.

    • metaRequests: MetaRequest[]

      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.

    Returns void

  • toString(): string
  • values(): IterableIterator<T>
  • Returns an iterator for values in the set.

    The iteration order is NOT eventually consistent: it may differ on replicas with the same state.

    Returns IterableIterator<T>

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