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Interface ISet<T, AddArgs, Events>

Interface for a collaborative set with values of type T.

For implementations, see CSet and CValueSet.

An ISet<T> represents a Set<T> and has similar methods. If conflicting add and delete calls on the same value are possible, then any semantics can be used to resolve them.

This interface permits add to accept arbitrary AddArgs instead of just the value to set. That is useful when the value is not serializable, e.g., a dynamically- created Collab.

Type Parameters

  • T

    The value type.

  • AddArgs extends unknown[] = [T]

    The type of arguments to add. Defaults to [T], i.e., add inputs the actual value.

  • Events extends SetEventsRecord<T> = SetEventsRecord<T>

    Events record.

Hierarchy

Implemented by

Index

Properties

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.

size: number

The number of values in the set.

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(...args: AddArgs): undefined | T
  • Adds a value to the set using args.

    Typically, args are broadcast to all replicas in serialized form. Every replica then uses them to contruct the actual value of type T.

    Parameters

    • Rest ...args: AddArgs

    Returns undefined | T

    The added value, or undefined if it is not constructed immediately.

  • canGC(): boolean
  • 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:

    1. The parent may choose to weakly reference this object to save memory (e.g., CLazyMap does so). If this becomes garbage collected, then is needed later, the parent will recreate it using the same constructor call.
    2. The parent may skip calling save during saving. When loading the resulting saved state, the parent will call 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.

    Returns boolean

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

    Returns void

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

    Parameters

    • value: T

    Returns void

  • emit<K>(eventName: K, event: Events[K] & CollabEvent, options?: { skipAnyEvent?: boolean }): void
  • 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

    • K extends string | number | symbol

    Parameters

    • eventName: K
    • event: Events[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.

    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.

    Returns void

  • forEach(callbackfn: ((value: T, value2: T, set: ISet<T, AddArgs, Events>) => 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: ISet<T, AddArgs, Events>) => void)

      Function to execute for each value. Its arguments are the value twice, then this set.

        • (value: T, value2: T, set: ISet<T, AddArgs, Events>): void
        • Parameters

          • value: T
          • value2: T
          • set: ISet<T, AddArgs, Events>

          Returns void

    • Optional thisArg: any

      Value to use as this when executing callbackfn.

    Returns void

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

    Parameters

    • value: T

    Returns boolean

  • 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.

    Parameters

    • savedStateTree: null | SavedStateTree

      The saved state to load, in the same format as in save, or null as described above.

    • meta: SavedStateMeta

      Metadata attached to this saved state by the runtime. It incorporates all possible metadata requests. Note that meta.updateType is always "savedState".

    Returns void

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

    Type Parameters

    • K extends string | number | symbol

    Parameters

    • eventName: K

      Name of the event to listen on.

    • handler: ((event: Events[K], caller: ISet<T, AddArgs, Events>) => void)

      Callback that handles the event.

        • (event: Events[K], caller: ISet<T, AddArgs, Events>): void
        • Parameters

          • event: Events[K]
          • caller: ISet<T, AddArgs, Events>

          Returns void

    • 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

    • messageStack: (string | Uint8Array)[]

      The message to receive, in the same format as in send. This method may mutate messageStack in-place (e.g., calling pop).

    • meta: MessageMeta

      Metadata attached to this message by the runtime. It incorporates metadata requests made in send. Note that meta.updateType is always "message".

    Returns void

  • 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.

    Returns SavedStateTree

    The saved state.

  • 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

  • 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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