parallel-es/src/common/parallel/slave/filter-iterator.ts

Simple parallelization for EcmaScript

import {IParallelTaskEnvironment} from "../";
/**
 * Returns a new iterator that only contains all elements for which the given predicate returns true
 * @param iterator the iterator to filter
 * @param predicate the predicate to use for filtering the elements
 * @param env the environment of the job
 * @param T type of the elements to filter
 * @returns an iterator only containing the elements where the predicate is true
 */
export function filterIterator<T>(iterator: Iterator<T>, predicate: (this: void, value: T, env: IParallelTaskEnvironment) => boolean, env: IParallelTaskEnvironment): Iterator<T> {
    return {
        next() {
            let current: IteratorResult<T>;
            /* tslint:disable:no-conditional-assignment */
            while (!(current = iterator.next()).done) {
                if (predicate(current.value, env)) {
                    return current;
                }
            }

            return current;
        }
    };
}