настройка webpack

node_modules/webpack/lib/util/deterministicGrouping.js

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+"use strict";
+
+// Simulations show these probabilities for a single change
+// 93.1% that one group is invalidated
+// 4.8% that two groups are invalidated
+// 1.1% that 3 groups are invalidated
+// 0.1% that 4 or more groups are invalidated
+//
+// And these for removing/adding 10 lexically adjacent files
+// 64.5% that one group is invalidated
+// 24.8% that two groups are invalidated
+// 7.8% that 3 groups are invalidated
+// 2.7% that 4 or more groups are invalidated
+//
+// And these for removing/adding 3 random files
+// 0% that one group is invalidated
+// 3.7% that two groups are invalidated
+// 80.8% that 3 groups are invalidated
+// 12.3% that 4 groups are invalidated
+// 3.2% that 5 or more groups are invalidated
+
+/**
+ *
+ * @param {string} a key
+ * @param {string} b key
+ * @returns {number} the similarity as number
+ */
+const similarity = (a, b) => {
+	const l = Math.min(a.length, b.length);
+	let dist = 0;
+	for (let i = 0; i < l; i++) {
+		const ca = a.charCodeAt(i);
+		const cb = b.charCodeAt(i);
+		dist += Math.max(0, 10 - Math.abs(ca - cb));
+	}
+	return dist;
+};
+
+/**
+ * @param {string} a key
+ * @param {string} b key
+ * @returns {string} the common part and a single char for the difference
+ */
+const getName = (a, b) => {
+	const l = Math.min(a.length, b.length);
+	let r = "";
+	for (let i = 0; i < l; i++) {
+		const ca = a.charAt(i);
+		const cb = b.charAt(i);
+		r += ca;
+		if (ca === cb) {
+			continue;
+		}
+		return r;
+	}
+	return a;
+};
+
+/**
+ * @template T
+ */
+class Node {
+	/**
+	 * @param {T} item item
+	 * @param {string} key key
+	 * @param {number} size size
+	 */
+	constructor(item, key, size) {
+		this.item = item;
+		this.key = key;
+		this.size = size;
+	}
+}
+
+/**
+ * @template T
+ */
+class Group {
+	/**
+	 * @param {Node<T>[]} nodes nodes
+	 * @param {number[]} similarities similarities between the nodes (length = nodes.length - 1)
+	 */
+	constructor(nodes, similarities) {
+		this.nodes = nodes;
+		this.similarities = similarities;
+		this.size = nodes.reduce((size, node) => size + node.size, 0);
+		/** @type {string} */
+		this.key = undefined;
+	}
+}
+
+/**
+ * @template T
+ * @typedef {Object} GroupedItems<T>
+ * @property {string} key
+ * @property {T[]} items
+ * @property {number} size
+ */
+
+/**
+ * @template T
+ * @typedef {Object} Options
+ * @property {number} maxSize maximum size of a group
+ * @property {number} minSize minimum size of a group (preferred over maximum size)
+ * @property {Iterable<T>} items a list of items
+ * @property {function(T): number} getSize function to get size of an item
+ * @property {function(T): string} getKey function to get the key of an item
+ */
+
+/**
+ * @template T
+ * @param {Options<T>} options options object
+ * @returns {GroupedItems<T>[]} grouped items
+ */
+module.exports = ({ maxSize, minSize, items, getSize, getKey }) => {
+	/** @type {Group<T>[]} */
+	const result = [];
+
+	const nodes = Array.from(
+		items,
+		item => new Node(item, getKey(item), getSize(item))
+	);
+
+	/** @type {Node<T>[]} */
+	const initialNodes = [];
+
+	// lexically ordering of keys
+	nodes.sort((a, b) => {
+		if (a.key < b.key) return -1;
+		if (a.key > b.key) return 1;
+		return 0;
+	});
+
+	// return nodes bigger than maxSize directly as group
+	for (const node of nodes) {
+		if (node.size >= maxSize) {
+			result.push(new Group([node], []));
+		} else {
+			initialNodes.push(node);
+		}
+	}
+
+	if (initialNodes.length > 0) {
+		// calculate similarities between lexically adjacent nodes
+		/** @type {number[]} */
+		const similarities = [];
+		for (let i = 1; i < initialNodes.length; i++) {
+			const a = initialNodes[i - 1];
+			const b = initialNodes[i];
+			similarities.push(similarity(a.key, b.key));
+		}
+
+		const initialGroup = new Group(initialNodes, similarities);
+
+		if (initialGroup.size < minSize) {
+			// We hit an edgecase where the working set is already smaller than minSize
+			// We merge it with the smallest result node to keep minSize intact
+			if (result.length > 0) {
+				const smallestGroup = result.reduce((min, group) =>
+					min.size > group.size ? group : min
+				);
+				for (const node of initialGroup.nodes) smallestGroup.nodes.push(node);
+				smallestGroup.nodes.sort((a, b) => {
+					if (a.key < b.key) return -1;
+					if (a.key > b.key) return 1;
+					return 0;
+				});
+			} else {
+				// There are no other nodes
+				// We use all nodes and have to accept that it's smaller than minSize
+				result.push(initialGroup);
+			}
+		} else {
+			const queue = [initialGroup];
+
+			while (queue.length) {
+				const group = queue.pop();
+				// only groups bigger than maxSize need to be splitted
+				if (group.size < maxSize) {
+					result.push(group);
+					continue;
+				}
+
+				// find unsplittable area from left and right
+				// going minSize from left and right
+				// at least one node need to be included otherwise we get stuck
+				let left = 0;
+				let leftSize = 0;
+				while (leftSize <= minSize) {
+					leftSize += group.nodes[left].size;
+					left++;
+				}
+				let right = group.nodes.length - 1;
+				let rightSize = 0;
+				while (rightSize <= minSize) {
+					rightSize += group.nodes[right].size;
+					right--;
+				}
+
+				if (left - 1 > right) {
+					// can't split group while holding minSize
+					// because minSize is preferred of maxSize we return
+					// the group here even while it's too big
+					// To avoid this make sure maxSize > minSize * 3
+					result.push(group);
+					continue;
+				}
+				if (left <= right) {
+					// when there is a area between left and right
+					// we look for best split point
+					// we split at the minimum similarity
+					// here key space is separated the most
+					let best = left - 1;
+					let bestSimilarity = group.similarities[best];
+					for (let i = left; i <= right; i++) {
+						const similarity = group.similarities[i];
+						if (similarity < bestSimilarity) {
+							best = i;
+							bestSimilarity = similarity;
+						}
+					}
+					left = best + 1;
+					right = best;
+				}
+
+				// create two new groups for left and right area
+				// and queue them up
+				const rightNodes = [group.nodes[right + 1]];
+				/** @type {number[]} */
+				const rightSimilaries = [];
+				for (let i = right + 2; i < group.nodes.length; i++) {
+					rightSimilaries.push(group.similarities[i - 1]);
+					rightNodes.push(group.nodes[i]);
+				}
+				queue.push(new Group(rightNodes, rightSimilaries));
+
+				const leftNodes = [group.nodes[0]];
+				/** @type {number[]} */
+				const leftSimilaries = [];
+				for (let i = 1; i < left; i++) {
+					leftSimilaries.push(group.similarities[i - 1]);
+					leftNodes.push(group.nodes[i]);
+				}
+				queue.push(new Group(leftNodes, leftSimilaries));
+			}
+		}
+	}
+
+	// lexically ordering
+	result.sort((a, b) => {
+		if (a.nodes[0].key < b.nodes[0].key) return -1;
+		if (a.nodes[0].key > b.nodes[0].key) return 1;
+		return 0;
+	});
+
+	// give every group a name
+	for (let i = 0; i < result.length; i++) {
+		const group = result[i];
+		const first = group.nodes[0];
+		const last = group.nodes[group.nodes.length - 1];
+		let name = getName(first.key, last.key);
+		group.key = name;
+	}
+
+	// return the results
+	return result.map(group => {
+		/** @type {GroupedItems} */
+		return {
+			key: group.key,
+			items: group.nodes.map(node => node.item),
+			size: group.size
+		};
+	});
+};