514 lines
14 KiB
JavaScript
514 lines
14 KiB
JavaScript
/*
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MIT License http://www.opensource.org/licenses/mit-license.php
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Author Tobias Koppers @sokra
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*/
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"use strict";
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// Simulations show these probabilities for a single change
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// 93.1% that one group is invalidated
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// 4.8% that two groups are invalidated
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// 1.1% that 3 groups are invalidated
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// 0.1% that 4 or more groups are invalidated
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//
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// And these for removing/adding 10 lexically adjacent files
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// 64.5% that one group is invalidated
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// 24.8% that two groups are invalidated
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// 7.8% that 3 groups are invalidated
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// 2.7% that 4 or more groups are invalidated
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//
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// And these for removing/adding 3 random files
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// 0% that one group is invalidated
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// 3.7% that two groups are invalidated
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// 80.8% that 3 groups are invalidated
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// 12.3% that 4 groups are invalidated
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// 3.2% that 5 or more groups are invalidated
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/**
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*
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* @param {string} a key
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* @param {string} b key
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* @returns {number} the similarity as number
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*/
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const similarity = (a, b) => {
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const l = Math.min(a.length, b.length);
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let dist = 0;
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for (let i = 0; i < l; i++) {
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const ca = a.charCodeAt(i);
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const cb = b.charCodeAt(i);
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dist += Math.max(0, 10 - Math.abs(ca - cb));
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}
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return dist;
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};
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/**
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* @param {string} a key
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* @param {string} b key
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* @param {Set<string>} usedNames set of already used names
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* @returns {string} the common part and a single char for the difference
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*/
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const getName = (a, b, usedNames) => {
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const l = Math.min(a.length, b.length);
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let i = 0;
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while (i < l) {
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if (a.charCodeAt(i) !== b.charCodeAt(i)) {
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i++;
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break;
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}
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i++;
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}
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while (i < l) {
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const name = a.slice(0, i);
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const lowerName = name.toLowerCase();
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if (!usedNames.has(lowerName)) {
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usedNames.add(lowerName);
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return name;
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}
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i++;
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}
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// names always contain a hash, so this is always unique
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// we don't need to check usedNames nor add it
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return a;
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};
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/**
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* @param {Record<string, number>} total total size
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* @param {Record<string, number>} size single size
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* @returns {void}
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*/
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const addSizeTo = (total, size) => {
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for (const key of Object.keys(size)) {
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total[key] = (total[key] || 0) + size[key];
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}
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};
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/**
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* @param {Record<string, number>} total total size
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* @param {Record<string, number>} size single size
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* @returns {void}
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*/
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const subtractSizeFrom = (total, size) => {
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for (const key of Object.keys(size)) {
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total[key] -= size[key];
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}
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};
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/**
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* @param {Iterable<Node>} nodes some nodes
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* @returns {Record<string, number>} total size
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*/
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const sumSize = nodes => {
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const sum = Object.create(null);
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for (const node of nodes) {
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addSizeTo(sum, node.size);
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}
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return sum;
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};
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const isTooBig = (size, maxSize) => {
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for (const key of Object.keys(size)) {
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const s = size[key];
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if (s === 0) continue;
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const maxSizeValue = maxSize[key];
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if (typeof maxSizeValue === "number") {
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if (s > maxSizeValue) return true;
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}
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}
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return false;
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};
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const isTooSmall = (size, minSize) => {
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for (const key of Object.keys(size)) {
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const s = size[key];
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if (s === 0) continue;
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const minSizeValue = minSize[key];
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if (typeof minSizeValue === "number") {
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if (s < minSizeValue) return true;
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}
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}
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return false;
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};
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const getTooSmallTypes = (size, minSize) => {
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const types = new Set();
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for (const key of Object.keys(size)) {
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const s = size[key];
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if (s === 0) continue;
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const minSizeValue = minSize[key];
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if (typeof minSizeValue === "number") {
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if (s < minSizeValue) types.add(key);
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}
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}
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return types;
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};
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const getNumberOfMatchingSizeTypes = (size, types) => {
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let i = 0;
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for (const key of Object.keys(size)) {
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if (size[key] !== 0 && types.has(key)) i++;
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}
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return i;
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};
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const selectiveSizeSum = (size, types) => {
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let sum = 0;
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for (const key of Object.keys(size)) {
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if (size[key] !== 0 && types.has(key)) sum += size[key];
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}
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return sum;
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};
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/**
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* @template T
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*/
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class Node {
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/**
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* @param {T} item item
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* @param {string} key key
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* @param {Record<string, number>} size size
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*/
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constructor(item, key, size) {
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this.item = item;
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this.key = key;
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this.size = size;
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}
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}
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/**
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* @template T
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*/
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class Group {
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/**
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* @param {Node<T>[]} nodes nodes
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* @param {number[]} similarities similarities between the nodes (length = nodes.length - 1)
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* @param {Record<string, number>=} size size of the group
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*/
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constructor(nodes, similarities, size) {
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this.nodes = nodes;
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this.similarities = similarities;
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this.size = size || sumSize(nodes);
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/** @type {string} */
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this.key = undefined;
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}
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/**
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* @param {function(Node): boolean} filter filter function
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* @returns {Node[]} removed nodes
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*/
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popNodes(filter) {
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const newNodes = [];
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const newSimilarities = [];
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const resultNodes = [];
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let lastNode;
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for (let i = 0; i < this.nodes.length; i++) {
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const node = this.nodes[i];
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if (filter(node)) {
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resultNodes.push(node);
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} else {
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if (newNodes.length > 0) {
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newSimilarities.push(
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lastNode === this.nodes[i - 1]
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? this.similarities[i - 1]
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: similarity(lastNode.key, node.key)
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);
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}
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newNodes.push(node);
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lastNode = node;
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}
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}
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if (resultNodes.length === this.nodes.length) return undefined;
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this.nodes = newNodes;
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this.similarities = newSimilarities;
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this.size = sumSize(newNodes);
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return resultNodes;
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}
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}
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/**
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* @param {Iterable<Node>} nodes nodes
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* @returns {number[]} similarities
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*/
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const getSimilarities = nodes => {
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// calculate similarities between lexically adjacent nodes
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/** @type {number[]} */
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const similarities = [];
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let last = undefined;
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for (const node of nodes) {
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if (last !== undefined) {
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similarities.push(similarity(last.key, node.key));
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}
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last = node;
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}
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return similarities;
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};
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/**
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* @template T
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* @typedef {Object} GroupedItems<T>
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* @property {string} key
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* @property {T[]} items
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* @property {Record<string, number>} size
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*/
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/**
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* @template T
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* @typedef {Object} Options
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* @property {Record<string, number>} maxSize maximum size of a group
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* @property {Record<string, number>} minSize minimum size of a group (preferred over maximum size)
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* @property {Iterable<T>} items a list of items
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* @property {function(T): Record<string, number>} getSize function to get size of an item
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* @property {function(T): string} getKey function to get the key of an item
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*/
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/**
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* @template T
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* @param {Options<T>} options options object
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* @returns {GroupedItems<T>[]} grouped items
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*/
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module.exports = ({ maxSize, minSize, items, getSize, getKey }) => {
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/** @type {Group<T>[]} */
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const result = [];
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const nodes = Array.from(
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items,
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item => new Node(item, getKey(item), getSize(item))
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);
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/** @type {Node<T>[]} */
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const initialNodes = [];
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// lexically ordering of keys
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nodes.sort((a, b) => {
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if (a.key < b.key) return -1;
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if (a.key > b.key) return 1;
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return 0;
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});
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// return nodes bigger than maxSize directly as group
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// But make sure that minSize is not violated
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for (const node of nodes) {
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if (isTooBig(node.size, maxSize) && !isTooSmall(node.size, minSize)) {
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result.push(new Group([node], []));
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} else {
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initialNodes.push(node);
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}
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}
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console.log(
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initialNodes.map(n => `${n.key} ${JSON.stringify(n.size)}`),
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maxSize
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);
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if (initialNodes.length > 0) {
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const initialGroup = new Group(initialNodes, getSimilarities(initialNodes));
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const removeProblematicNodes = (group, consideredSize = group.size) => {
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const problemTypes = getTooSmallTypes(consideredSize, minSize);
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if (problemTypes.size > 0) {
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// We hit an edge case where the working set is already smaller than minSize
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// We merge problematic nodes with the smallest result node to keep minSize intact
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const problemNodes = group.popNodes(
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n => getNumberOfMatchingSizeTypes(n.size, problemTypes) > 0
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);
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if (problemNodes === undefined) return false;
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// Only merge it with result nodes that have the problematic size type
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const possibleResultGroups = result.filter(
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n => getNumberOfMatchingSizeTypes(n.size, problemTypes) > 0
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);
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if (possibleResultGroups.length > 0) {
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const bestGroup = possibleResultGroups.reduce((min, group) => {
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const minMatches = getNumberOfMatchingSizeTypes(min, problemTypes);
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const groupMatches = getNumberOfMatchingSizeTypes(
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group,
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problemTypes
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);
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if (minMatches !== groupMatches)
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return minMatches < groupMatches ? group : min;
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if (
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selectiveSizeSum(min.size, problemTypes) >
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selectiveSizeSum(group.size, problemTypes)
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)
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return group;
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return min;
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});
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for (const node of problemNodes) bestGroup.nodes.push(node);
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bestGroup.nodes.sort((a, b) => {
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if (a.key < b.key) return -1;
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if (a.key > b.key) return 1;
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return 0;
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});
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} else {
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// There are no other nodes with the same size types
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// We create a new group and have to accept that it's smaller than minSize
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result.push(new Group(problemNodes, null));
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}
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return true;
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} else {
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return false;
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}
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};
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if (initialGroup.nodes.length > 0) {
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const queue = [initialGroup];
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while (queue.length) {
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const group = queue.pop();
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// only groups bigger than maxSize need to be splitted
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if (!isTooBig(group.size, maxSize)) {
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result.push(group);
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continue;
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}
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// If the group is already too small
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// we try to work only with the unproblematic nodes
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if (removeProblematicNodes(group)) {
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// This changed something, so we try this group again
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queue.push(group);
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continue;
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}
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// find unsplittable area from left and right
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// going minSize from left and right
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// at least one node need to be included otherwise we get stuck
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let left = 1;
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let leftSize = Object.create(null);
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addSizeTo(leftSize, group.nodes[0].size);
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while (left < group.nodes.length && isTooSmall(leftSize, minSize)) {
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addSizeTo(leftSize, group.nodes[left].size);
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left++;
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}
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let right = group.nodes.length - 2;
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let rightSize = Object.create(null);
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addSizeTo(rightSize, group.nodes[group.nodes.length - 1].size);
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while (right >= 0 && isTooSmall(rightSize, minSize)) {
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addSizeTo(rightSize, group.nodes[right].size);
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right--;
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}
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// left v v right
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// [ O O O ] O O O [ O O O ]
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// ^^^^^^^^^ leftSize
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// rightSize ^^^^^^^^^
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// leftSize > minSize
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// rightSize > minSize
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// Perfect split: [ O O O ] [ O O O ]
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// right === left - 1
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if (left - 1 > right) {
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// We try to remove some problematic nodes to "fix" that
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let prevSize;
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if (right < group.nodes.length - left) {
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subtractSizeFrom(rightSize, group.nodes[right + 1].size);
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prevSize = rightSize;
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} else {
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subtractSizeFrom(leftSize, group.nodes[left - 1].size);
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prevSize = leftSize;
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}
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if (removeProblematicNodes(group, prevSize)) {
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// This changed something, so we try this group again
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queue.push(group);
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continue;
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}
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// can't split group while holding minSize
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// because minSize is preferred of maxSize we return
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// the problematic nodes as result here even while it's too big
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// To avoid this make sure maxSize > minSize * 3
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result.push(group);
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continue;
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}
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if (left <= right) {
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// when there is a area between left and right
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// we look for best split point
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// we split at the minimum similarity
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// here key space is separated the most
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// But we also need to make sure to not create too small groups
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let best = -1;
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let bestSimilarity = Infinity;
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let pos = left;
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let rightSize = sumSize(group.nodes.slice(pos));
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// pos v v right
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// [ O O O ] O O O [ O O O ]
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// ^^^^^^^^^ leftSize
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// rightSize ^^^^^^^^^^^^^^^
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while (pos <= right + 1) {
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const similarity = group.similarities[pos - 1];
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if (
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similarity < bestSimilarity &&
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!isTooSmall(leftSize, minSize) &&
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!isTooSmall(rightSize, minSize)
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) {
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best = pos;
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bestSimilarity = similarity;
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}
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addSizeTo(leftSize, group.nodes[pos].size);
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subtractSizeFrom(rightSize, group.nodes[pos].size);
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pos++;
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}
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if (best < 0) {
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// This can't happen
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// but if that assumption is wrong
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// fallback to a big group
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result.push(group);
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continue;
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}
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left = best;
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right = best - 1;
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}
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// create two new groups for left and right area
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// and queue them up
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const rightNodes = [group.nodes[right + 1]];
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/** @type {number[]} */
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const rightSimilarities = [];
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for (let i = right + 2; i < group.nodes.length; i++) {
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rightSimilarities.push(group.similarities[i - 1]);
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rightNodes.push(group.nodes[i]);
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}
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queue.push(new Group(rightNodes, rightSimilarities));
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const leftNodes = [group.nodes[0]];
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/** @type {number[]} */
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const leftSimilarities = [];
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for (let i = 1; i < left; i++) {
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leftSimilarities.push(group.similarities[i - 1]);
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leftNodes.push(group.nodes[i]);
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}
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queue.push(new Group(leftNodes, leftSimilarities));
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}
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}
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}
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// lexically ordering
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result.sort((a, b) => {
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if (a.nodes[0].key < b.nodes[0].key) return -1;
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if (a.nodes[0].key > b.nodes[0].key) return 1;
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return 0;
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});
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// give every group a name
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const usedNames = new Set();
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for (let i = 0; i < result.length; i++) {
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const group = result[i];
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if (group.nodes.length === 1) {
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group.key = group.nodes[0].key;
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} else {
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const first = group.nodes[0];
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const last = group.nodes[group.nodes.length - 1];
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const name = getName(first.key, last.key, usedNames);
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group.key = name;
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}
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}
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// return the results
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return result.map(group => {
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/** @type {GroupedItems} */
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return {
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key: group.key,
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items: group.nodes.map(node => node.item),
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size: group.size
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};
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});
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};
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