eris-keys/node_modules/ramda/src/intersectionWith.js

a JavaScript client library for eris-keys

var _containsWith = require('./internal/_containsWith');
var _curry3 = require('./internal/_curry3');
var uniqWith = require('./uniqWith');


/**
 * Combines two lists into a set (i.e. no duplicates) composed of those
 * elements common to both lists. Duplication is determined according to the
 * value returned by applying the supplied predicate to two list elements.
 *
 * @func
 * @memberOf R
 * @since v0.1.0
 * @category Relation
 * @sig ((a, a) -> Boolean) -> [a] -> [a] -> [a]
 * @param {Function} pred A predicate function that determines whether
 *        the two supplied elements are equal.
 * @param {Array} list1 One list of items to compare
 * @param {Array} list2 A second list of items to compare
 * @return {Array} A new list containing those elements common to both lists.
 * @see R.intersection
 * @example
 *
 *      var buffaloSpringfield = [
 *        {id: 824, name: 'Richie Furay'},
 *        {id: 956, name: 'Dewey Martin'},
 *        {id: 313, name: 'Bruce Palmer'},
 *        {id: 456, name: 'Stephen Stills'},
 *        {id: 177, name: 'Neil Young'}
 *      ];
 *      var csny = [
 *        {id: 204, name: 'David Crosby'},
 *        {id: 456, name: 'Stephen Stills'},
 *        {id: 539, name: 'Graham Nash'},
 *        {id: 177, name: 'Neil Young'}
 *      ];
 *
 *      R.intersectionWith(R.eqBy(R.prop('id')), buffaloSpringfield, csny);
 *      //=> [{id: 456, name: 'Stephen Stills'}, {id: 177, name: 'Neil Young'}]
 */
module.exports = _curry3(function intersectionWith(pred, list1, list2) {
  var lookupList, filteredList;
  if (list1.length > list2.length) {
    lookupList = list1;
    filteredList = list2;
  } else {
    lookupList = list2;
    filteredList = list1;
  }
  var results = [];
  var idx = 0;
  while (idx < filteredList.length) {
    if (_containsWith(pred, filteredList[idx], lookupList)) {
      results[results.length] = filteredList[idx];
    }
    idx += 1;
  }
  return uniqWith(pred, results);
});