/* MIT License http://www.opensource.org/licenses/mit-license.php Author Tobias Koppers @sokra */ "use strict"; /** * intersect creates Set containing the intersection of elements between all sets * @template T * @param {Set[]} sets an array of sets being checked for shared elements * @returns {Set} returns a new Set containing the intersecting items */ const intersect = sets => { if (sets.length === 0) return new Set(); if (sets.length === 1) return new Set(sets[0]); let minSize = Infinity; let minIndex = -1; for (let i = 0; i < sets.length; i++) { const size = sets[i].size; if (size < minSize) { minIndex = i; minSize = size; } } const current = new Set(sets[minIndex]); for (let i = 0; i < sets.length; i++) { if (i === minIndex) continue; const set = sets[i]; for (const item of current) { if (!set.has(item)) { current.delete(item); } } } return current; }; /** * Checks if a set is the subset of another set * @template T * @param {Set} bigSet a Set which contains the original elements to compare against * @param {Set} smallSet the set whose elements might be contained inside of bigSet * @returns {boolean} returns true if smallSet contains all elements inside of the bigSet */ const isSubset = (bigSet, smallSet) => { if (bigSet.size < smallSet.size) return false; for (const item of smallSet) { if (!bigSet.has(item)) return false; } return true; }; /** * @template T * @param {Set} set a set * @param {function(T): boolean} fn selector function * @returns {T | undefined} found item */ const find = (set, fn) => { for (const item of set) { if (fn(item)) return item; } }; /** * @template T * @param {Set} set a set * @returns {T | undefined} first item */ const first = set => { const entry = set.values().next(); return entry.done ? undefined : entry.value; }; /** * @template T * @param {Set} a first * @param {Set} b second * @returns {Set} combined set, may be identical to a or b */ const combine = (a, b) => { if (b.size === 0) return a; if (a.size === 0) return b; const set = new Set(a); for (const item of b) set.add(item); return set; }; exports.intersect = intersect; exports.isSubset = isSubset; exports.find = find; exports.first = first; exports.combine = combine;