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CommandChange ​

What a history source emits for each applied command. See origins.

ts
type CommandOrigin = "local" | "remote" | "replay";

class CommandChange<TCommand, TImage> {
  static local(command: TCommand, image: TImage, inverse?: readonly TCommand[], basis?: number): CommandChange<TCommand, TImage>;
  static remote(command: TCommand, image: TImage, clientId?: string | null): CommandChange<TCommand, TImage>;
  static replay(command: TCommand, image: TImage): CommandChange<TCommand, TImage>;

  readonly command: TCommand;
  readonly origin: CommandOrigin;
  readonly image: TImage;
  readonly inverse: readonly TCommand[];
  readonly clientId: string | null;
  readonly basis: number | undefined;
}

Build a change for a source that is not a CommandDocument with the constructor of its origin: each one sets the fields that origin carries and leaves the others empty.

ts
const change = CommandChange.local(command, null, inverse, basis);

Constructors ​

local(command, image, inverse?, basis?) ​

This person's edit. inverse defaults to []; pass basis for an undo or redo.

remote(command, image, clientId?) ​

A peer's command. clientId defaults to null.

replay(command, image) ​

This client's pending command re-applied after a peer's.

Properties ​

command ​

The applied command.

origin ​

local for this person's edit, remote for a peer's command, replay for this client's pending command re-applied after a peer's.

image ​

What the command replaced, read before it applied.

inverse ​

The commands undoing it. Empty unless origin is local.

clientId ​

The peer behind a remote change; null otherwise.

basis ​

Set on an undo or redo: the room version of the step it replays. undefined otherwise.