Class RuleEngine

constructor

• new RuleEngine(
      rules: string | RuleEvaluator,
      link: ReceivingLink,
      options?: RuleEngineOptions,
  ): RuleEngine

  Assembles an engine.

  Parameters

  • rules: string | RuleEvaluator

    the rule file's text, or an evaluator already loaded from it.

  • link: ReceivingLink

    the link readings arrive on and actions publish over.

  • options: RuleEngineOptions = {}

    the outputs the rules drive, and how a message is read.

  Returns RuleEngine

  Throws

  when the rule file is refused, with the rule and the reason.

Readonlyevaluator

actuators

• get actuators(): string[]

  The outputs the rules drive, each once, in name order.

  Returns string[]

topics

• get topics(): string[]

  The topics the rules watch, each once, in name order.

  Returns string[]

isSet

• isSet(rule: string): boolean | null

  Whether a rule's condition holds.

  Parameters

  • rule: string

    the rule's name.

  Returns boolean | null

  the state, or null for a name no rule has.

listen

• listen(): Promise<void>

  Checks the engine was given every output a rule drives, and subscribes to every watched topic.

  Returns Promise<void>

  Throws

  when a rule drives an output the engine was not given, naming it.

run

• run(options?: EngineRunOptions): Promise<void>

  Handles messages until stopped.

  Parameters

  • options: EngineRunOptions = {}

    when to stop, and what to hear.

  Returns Promise<void>

  once the signal aborts, the messages run out, or the link ends.

  Throws

  the failure of a message when no onError hears it.

step

• step(timeoutMs?: number): Promise<RuleFired[] | null>

  Waits for one message and runs every rule that watches its topic.

  Parameters

  • OptionaltimeoutMs: number

    how long to wait; for good unless given.

  Returns Promise<RuleFired[] | null>

  what fired, which is empty when the message set or cleared nothing, or null when no message arrived in time or the link has ended.

  Throws

  when a reading on a watched topic does not decode to a finite number, or an action fails.