| 1 | /*
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| 2 | MIT License http://www.opensource.org/licenses/mit-license.php
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| 3 | Author Tobias Koppers @sokra
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| 4 | */
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| 5 |
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| 6 | "use strict";
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| 7 |
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| 8 | const { first } = require("./SetHelpers");
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| 9 | const SortableSet = require("./SortableSet");
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| 10 |
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| 11 | /**
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| 12 | * Callback that extracts the grouping key for an item at one bucket layer.
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| 13 | * @template T
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| 14 | * @template K
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| 15 | * @typedef {(item: T) => K} GetKey
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| 16 | */
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| 17 |
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| 18 | /**
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| 19 | * Comparison function used to order keys or leaf items.
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| 20 | * @template T
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| 21 | * @typedef {(a: T, n: T) => number} Comparator
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| 22 | */
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| 23 |
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| 24 | /**
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| 25 | * Internal bucket entry, either another nested bucket set or a sorted leaf set.
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| 26 | * @template T
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| 27 | * @template K
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| 28 | * @typedef {LazyBucketSortedSet<T, K> | SortableSet<T>} Entry
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| 29 | */
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| 30 |
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| 31 | /**
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| 32 | * Constructor argument accepted for nested bucket layers or the final leaf
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| 33 | * comparator.
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| 34 | * @template T
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| 35 | * @template K
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| 36 | * @typedef {GetKey<T, K> | Comparator<K> | Comparator<T>} Arg
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| 37 | */
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| 38 |
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| 39 | /**
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| 40 | * Multi layer bucket sorted set:
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| 41 | * Supports adding non-existing items (DO NOT ADD ITEM TWICE),
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| 42 | * Supports removing exiting items (DO NOT REMOVE ITEM NOT IN SET),
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| 43 | * Supports popping the first items according to defined order,
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| 44 | * Supports iterating all items without order,
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| 45 | * Supports updating an item in an efficient way,
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| 46 | * Supports size property, which is the number of items,
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| 47 | * Items are lazy partially sorted when needed
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| 48 | * @template T
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| 49 | * @template K
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| 50 | */
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| 51 | class LazyBucketSortedSet {
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| 52 | /**
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| 53 | * Creates a lazily sorted, potentially multi-level bucket structure whose
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| 54 | * order is only fully resolved when items are popped.
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| 55 | * @param {GetKey<T, K>} getKey function to get key from item
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| 56 | * @param {Comparator<K>=} comparator comparator to sort keys
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| 57 | * @param {...Arg<T, K>} args more pairs of getKey and comparator plus optional final comparator for the last layer
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| 58 | */
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| 59 | constructor(getKey, comparator, ...args) {
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| 60 | this._getKey = getKey;
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| 61 | this._innerArgs = args;
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| 62 | this._leaf = args.length <= 1;
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| 63 | this._keys = new SortableSet(undefined, comparator);
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| 64 | /** @type {Map<K, Entry<T, K>>} */
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| 65 | this._map = new Map();
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| 66 | /** @type {Set<T>} */
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| 67 | this._unsortedItems = new Set();
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| 68 | this.size = 0;
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| 69 | }
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| 70 |
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| 71 | /**
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| 72 | * Adds an item to the unsorted staging area so sorting can be deferred until
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| 73 | * an ordered pop is requested.
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| 74 | * @param {T} item an item
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| 75 | * @returns {void}
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| 76 | */
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| 77 | add(item) {
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| 78 | this.size++;
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| 79 | this._unsortedItems.add(item);
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| 80 | }
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| 81 |
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| 82 | /**
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| 83 | * Inserts an item into the correct nested bucket, creating intermediate
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| 84 | * bucket structures on demand.
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| 85 | * @param {K} key key of item
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| 86 | * @param {T} item the item
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| 87 | * @returns {void}
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| 88 | */
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| 89 | _addInternal(key, item) {
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| 90 | let entry = this._map.get(key);
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| 91 | if (entry === undefined) {
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| 92 | entry = this._leaf
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| 93 | ? new SortableSet(
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| 94 | undefined,
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| 95 | /** @type {Comparator<T>} */
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| 96 | (this._innerArgs[0])
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| 97 | )
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| 98 | : new LazyBucketSortedSet(
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| 99 | .../** @type {[GetKey<T, K>, Comparator<K>]} */
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| 100 | (this._innerArgs)
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| 101 | );
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| 102 | this._keys.add(key);
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| 103 | this._map.set(key, entry);
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| 104 | }
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| 105 | entry.add(item);
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| 106 | }
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| 107 |
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| 108 | /**
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| 109 | * Removes an item from either the unsorted staging area or its resolved
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| 110 | * bucket and prunes empty buckets as needed.
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| 111 | * @param {T} item an item
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| 112 | * @returns {void}
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| 113 | */
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| 114 | delete(item) {
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| 115 | this.size--;
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| 116 | if (this._unsortedItems.has(item)) {
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| 117 | this._unsortedItems.delete(item);
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| 118 | return;
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| 119 | }
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| 120 | const key = this._getKey(item);
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| 121 | const entry = /** @type {Entry<T, K>} */ (this._map.get(key));
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| 122 | entry.delete(item);
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| 123 | if (entry.size === 0) {
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| 124 | this._deleteKey(key);
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| 125 | }
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| 126 | }
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| 127 |
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| 128 | /**
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| 129 | * Removes an empty bucket key and its corresponding nested entry.
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| 130 | * @param {K} key key to be removed
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| 131 | * @returns {void}
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| 132 | */
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| 133 | _deleteKey(key) {
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| 134 | this._keys.delete(key);
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| 135 | this._map.delete(key);
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| 136 | }
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| 137 |
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| 138 | /**
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| 139 | * Removes and returns the smallest item according to the configured bucket
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| 140 | * order, sorting only the portions of the structure that are needed.
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| 141 | * @returns {T | undefined} an item
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| 142 | */
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| 143 | popFirst() {
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| 144 | if (this.size === 0) return;
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| 145 | this.size--;
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| 146 | if (this._unsortedItems.size > 0) {
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| 147 | for (const item of this._unsortedItems) {
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| 148 | const key = this._getKey(item);
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| 149 | this._addInternal(key, item);
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| 150 | }
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| 151 | this._unsortedItems.clear();
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| 152 | }
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| 153 | this._keys.sort();
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| 154 | const key = /** @type {K} */ (first(this._keys));
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| 155 | const entry = this._map.get(key);
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| 156 | if (this._leaf) {
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| 157 | const leafEntry = /** @type {SortableSet<T>} */ (entry);
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| 158 | leafEntry.sort();
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| 159 | const item = /** @type {T} */ (first(leafEntry));
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| 160 | leafEntry.delete(item);
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| 161 | if (leafEntry.size === 0) {
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| 162 | this._deleteKey(key);
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| 163 | }
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| 164 | return item;
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| 165 | }
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| 166 | const nodeEntry =
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| 167 | /** @type {LazyBucketSortedSet<T, K>} */
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| 168 | (entry);
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| 169 | const item = nodeEntry.popFirst();
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| 170 | if (nodeEntry.size === 0) {
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| 171 | this._deleteKey(key);
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| 172 | }
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| 173 | return item;
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| 174 | }
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| 175 |
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| 176 | /**
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| 177 | * Begins an in-place update for an item and returns a completion callback
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| 178 | * that can either reinsert it under a new key or remove it entirely.
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| 179 | * @param {T} item to be updated item
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| 180 | * @returns {(remove?: true) => void} finish update
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| 181 | */
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| 182 | startUpdate(item) {
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| 183 | if (this._unsortedItems.has(item)) {
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| 184 | return (remove) => {
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| 185 | if (remove) {
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| 186 | this._unsortedItems.delete(item);
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| 187 | this.size--;
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| 188 | }
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| 189 | };
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| 190 | }
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| 191 | const key = this._getKey(item);
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| 192 | if (this._leaf) {
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| 193 | const oldEntry = /** @type {SortableSet<T>} */ (this._map.get(key));
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| 194 | return (remove) => {
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| 195 | if (remove) {
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| 196 | this.size--;
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| 197 | oldEntry.delete(item);
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| 198 | if (oldEntry.size === 0) {
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| 199 | this._deleteKey(key);
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| 200 | }
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| 201 | return;
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| 202 | }
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| 203 | const newKey = this._getKey(item);
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| 204 | if (key === newKey) {
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| 205 | // This flags the sortable set as unordered
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| 206 | oldEntry.add(item);
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| 207 | } else {
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| 208 | oldEntry.delete(item);
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| 209 | if (oldEntry.size === 0) {
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| 210 | this._deleteKey(key);
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| 211 | }
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| 212 | this._addInternal(newKey, item);
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| 213 | }
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| 214 | };
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| 215 | }
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| 216 | const oldEntry =
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| 217 | /** @type {LazyBucketSortedSet<T, K>} */
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| 218 | (this._map.get(key));
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| 219 | const finishUpdate = oldEntry.startUpdate(item);
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| 220 | return (remove) => {
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| 221 | if (remove) {
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| 222 | this.size--;
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| 223 | finishUpdate(true);
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| 224 | if (oldEntry.size === 0) {
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| 225 | this._deleteKey(key);
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| 226 | }
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| 227 | return;
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| 228 | }
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| 229 | const newKey = this._getKey(item);
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| 230 | if (key === newKey) {
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| 231 | finishUpdate();
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| 232 | } else {
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| 233 | finishUpdate(true);
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| 234 | if (oldEntry.size === 0) {
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| 235 | this._deleteKey(key);
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| 236 | }
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| 237 | this._addInternal(newKey, item);
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| 238 | }
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| 239 | };
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| 240 | }
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| 241 |
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| 242 | /**
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| 243 | * Appends iterators for every stored bucket and leaf to support unordered
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| 244 | * traversal across the entire structure.
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| 245 | * @param {Iterator<T>[]} iterators list of iterators to append to
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| 246 | * @returns {void}
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| 247 | */
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| 248 | _appendIterators(iterators) {
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| 249 | if (this._unsortedItems.size > 0) {
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| 250 | iterators.push(this._unsortedItems[Symbol.iterator]());
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| 251 | }
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| 252 | for (const key of this._keys) {
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| 253 | const entry = this._map.get(key);
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| 254 | if (this._leaf) {
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| 255 | const leafEntry = /** @type {SortableSet<T>} */ (entry);
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| 256 | const iterator = leafEntry[Symbol.iterator]();
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| 257 | iterators.push(iterator);
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| 258 | } else {
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| 259 | const nodeEntry =
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| 260 | /** @type {LazyBucketSortedSet<T, K>} */
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| 261 | (entry);
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| 262 | nodeEntry._appendIterators(iterators);
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| 263 | }
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| 264 | }
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| 265 | }
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| 266 |
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| 267 | /**
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| 268 | * Iterates over all stored items without imposing bucket sort order.
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| 269 | * @returns {Iterator<T>} the iterator
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| 270 | */
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| 271 | [Symbol.iterator]() {
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| 272 | /** @type {Iterator<T>[]} */
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| 273 | const iterators = [];
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| 274 | this._appendIterators(iterators);
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| 275 | iterators.reverse();
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| 276 | let currentIterator =
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| 277 | /** @type {Iterator<T>} */
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| 278 | (iterators.pop());
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| 279 | return {
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| 280 | next: () => {
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| 281 | const res = currentIterator.next();
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| 282 | if (res.done) {
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| 283 | if (iterators.length === 0) return res;
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| 284 | currentIterator = /** @type {Iterator<T>} */ (iterators.pop());
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| 285 | return currentIterator.next();
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| 286 | }
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| 287 | return res;
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| 288 | }
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| 289 | };
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| 290 | }
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| 291 | }
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| 292 |
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| 293 | module.exports = LazyBucketSortedSet;
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