langchain/src/util/set.ts

/**
 * Source: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set#implementing_basic_set_operations
 */

/**
 * returns intersection of two sets
 */
export function intersection<T>(setA: Set<T>, setB: Set<T>) {
  const _intersection = new Set<T>();
  for (const elem of setB) {
    if (setA.has(elem)) {
      _intersection.add(elem);
    }
  }
  return _intersection;
}

/**
 * returns union of two sets
 */
export function union<T>(setA: Set<T>, setB: Set<T>) {
  const _union = new Set(setA);
  for (const elem of setB) {
    _union.add(elem);
  }
  return _union;
}

/**
 * returns difference of two sets
 */
export function difference<T>(setA: Set<T>, setB: Set<T>) {
  const _difference = new Set(setA);
  for (const elem of setB) {
    _difference.delete(elem);
  }
  return _difference;
}