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/*
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<T>[]} sets an array of sets being checked for shared elements
* @returns {Set<T>} 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<T>} bigSet a Set which contains the original elements to compare against
* @param {Set<T>} 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<T>} 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<T>} 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<T>} a first
* @param {Set<T>} b second
* @returns {Set<T>} 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;
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