Function filter

packages/db-ivm/src/operators/filter.ts:32–47

(f: (data: T) => boolean)

 * @param f - The predicate to filter elements
 */
export function filter<T>(f: (data: T) => boolean): PipedOperator<T, T> {
  return (stream: IStreamBuilder<T>): IStreamBuilder<T> => {
    const output = new StreamBuilder<T>(
      stream.graph,
      new DifferenceStreamWriter<T>(),
    )
    const operator = new FilterOperator<T>(
      stream.graph.getNextOperatorId(),
      stream.connectReader(),
      output.writer,
      f,
    )
    stream.graph.addOperator(operator)
    return output
  }
}