source: trip-planner-front/node_modules/webpack/lib/util/LazyBucketSortedSet.js@ 8d391a1

/*
        MIT License http://www.opensource.org/licenses/mit-license.php
        Author Tobias Koppers @sokra
*/

"use strict";

const { first } = require("./SetHelpers");
const SortableSet = require("./SortableSet");

/**
 * Multi layer bucket sorted set:
 * Supports adding non-existing items (DO NOT ADD ITEM TWICE),
 * Supports removing exiting items (DO NOT REMOVE ITEM NOT IN SET),
 * Supports popping the first items according to defined order,
 * Supports iterating all items without order,
 * Supports updating an item in an efficient way,
 * Supports size property, which is the number of items,
 * Items are lazy partially sorted when needed
 * @template T
 * @template K
 */
class LazyBucketSortedSet {
        /**
         * @param {function(T): K} getKey function to get key from item
         * @param {function(K, K): number} comparator comparator to sort keys
         * @param  {...((function(T): any) | (function(any, any): number))} args more pairs of getKey and comparator plus optional final comparator for the last layer
         */
        constructor(getKey, comparator, ...args) {
                this._getKey = getKey;
                this._innerArgs = args;
                this._leaf = args.length <= 1;
                this._keys = new SortableSet(undefined, comparator);
                /** @type {Map<K, LazyBucketSortedSet<T, any> | SortableSet<T>>} */
                this._map = new Map();
                this._unsortedItems = new Set();
                this.size = 0;
        }

        /**
         * @param {T} item an item
         * @returns {void}
         */
        add(item) {
                this.size++;
                this._unsortedItems.add(item);
        }

        /**
         * @param {K} key key of item
         * @param {T} item the item
         * @returns {void}
         */
        _addInternal(key, item) {
                let entry = this._map.get(key);
                if (entry === undefined) {
                        entry = this._leaf
                                ? new SortableSet(undefined, this._innerArgs[0])
                                : new /** @type {any} */ (LazyBucketSortedSet)(...this._innerArgs);
                        this._keys.add(key);
                        this._map.set(key, entry);
                }
                entry.add(item);
        }

        /**
         * @param {T} item an item
         * @returns {void}
         */
        delete(item) {
                this.size--;
                if (this._unsortedItems.has(item)) {
                        this._unsortedItems.delete(item);
                        return;
                }
                const key = this._getKey(item);
                const entry = this._map.get(key);
                entry.delete(item);
                if (entry.size === 0) {
                        this._deleteKey(key);
                }
        }

        /**
         * @param {K} key key to be removed
         * @returns {void}
         */
        _deleteKey(key) {
                this._keys.delete(key);
                this._map.delete(key);
        }

        /**
         * @returns {T | undefined} an item
         */
        popFirst() {
                if (this.size === 0) return undefined;
                this.size--;
                if (this._unsortedItems.size > 0) {
                        for (const item of this._unsortedItems) {
                                const key = this._getKey(item);
                                this._addInternal(key, item);
                        }
                        this._unsortedItems.clear();
                }
                this._keys.sort();
                const key = first(this._keys);
                const entry = this._map.get(key);
                if (this._leaf) {
                        const leafEntry = /** @type {SortableSet<T>} */ (entry);
                        leafEntry.sort();
                        const item = first(leafEntry);
                        leafEntry.delete(item);
                        if (leafEntry.size === 0) {
                                this._deleteKey(key);
                        }
                        return item;
                } else {
                        const nodeEntry = /** @type {LazyBucketSortedSet<T, any>} */ (entry);
                        const item = nodeEntry.popFirst();
                        if (nodeEntry.size === 0) {
                                this._deleteKey(key);
                        }
                        return item;
                }
        }

        /**
         * @param {T} item to be updated item
         * @returns {function(true=): void} finish update
         */
        startUpdate(item) {
                if (this._unsortedItems.has(item)) {
                        return remove => {
                                if (remove) {
                                        this._unsortedItems.delete(item);
                                        this.size--;
                                        return;
                                }
                        };
                }
                const key = this._getKey(item);
                if (this._leaf) {
                        const oldEntry = /** @type {SortableSet<T>} */ (this._map.get(key));
                        return remove => {
                                if (remove) {
                                        this.size--;
                                        oldEntry.delete(item);
                                        if (oldEntry.size === 0) {
                                                this._deleteKey(key);
                                        }
                                        return;
                                }
                                const newKey = this._getKey(item);
                                if (key === newKey) {
                                        // This flags the sortable set as unordered
                                        oldEntry.add(item);
                                } else {
                                        oldEntry.delete(item);
                                        if (oldEntry.size === 0) {
                                                this._deleteKey(key);
                                        }
                                        this._addInternal(newKey, item);
                                }
                        };
                } else {
                        const oldEntry = /** @type {LazyBucketSortedSet<T, any>} */ (
                                this._map.get(key)
                        );
                        const finishUpdate = oldEntry.startUpdate(item);
                        return remove => {
                                if (remove) {
                                        this.size--;
                                        finishUpdate(true);
                                        if (oldEntry.size === 0) {
                                                this._deleteKey(key);
                                        }
                                        return;
                                }
                                const newKey = this._getKey(item);
                                if (key === newKey) {
                                        finishUpdate();
                                } else {
                                        finishUpdate(true);
                                        if (oldEntry.size === 0) {
                                                this._deleteKey(key);
                                        }
                                        this._addInternal(newKey, item);
                                }
                        };
                }
        }

        /**
         * @param {Iterator<T>[]} iterators list of iterators to append to
         * @returns {void}
         */
        _appendIterators(iterators) {
                if (this._unsortedItems.size > 0)
                        iterators.push(this._unsortedItems[Symbol.iterator]());
                for (const key of this._keys) {
                        const entry = this._map.get(key);
                        if (this._leaf) {
                                const leafEntry = /** @type {SortableSet<T>} */ (entry);
                                const iterator = leafEntry[Symbol.iterator]();
                                iterators.push(iterator);
                        } else {
                                const nodeEntry = /** @type {LazyBucketSortedSet<T, any>} */ (entry);
                                nodeEntry._appendIterators(iterators);
                        }
                }
        }

        /**
         * @returns {Iterator<T>} the iterator
         */
        [Symbol.iterator]() {
                const iterators = [];
                this._appendIterators(iterators);
                iterators.reverse();
                let currentIterator = iterators.pop();
                return {
                        next: () => {
                                const res = currentIterator.next();
                                if (res.done) {
                                        if (iterators.length === 0) return res;
                                        currentIterator = iterators.pop();
                                        return currentIterator.next();
                                }
                                return res;
                        }
                };
        }
}

module.exports = LazyBucketSortedSet;