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app_vue/node_modules/webpack/lib/optimize/LimitChunkCountPlugin.js

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+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Tobias Koppers @sokra
+*/
+
+"use strict";
+
+const { STAGE_ADVANCED } = require("../OptimizationStages");
+const LazyBucketSortedSet = require("../util/LazyBucketSortedSet");
+const { compareChunks } = require("../util/comparators");
+const createSchemaValidation = require("../util/create-schema-validation");
+
+/** @typedef {import("../../declarations/plugins/optimize/LimitChunkCountPlugin").LimitChunkCountPluginOptions} LimitChunkCountPluginOptions */
+/** @typedef {import("../Chunk")} Chunk */
+/** @typedef {import("../Compiler")} Compiler */
+
+const validate = createSchemaValidation(
+	require("../../schemas/plugins/optimize/LimitChunkCountPlugin.check.js"),
+	() => require("../../schemas/plugins/optimize/LimitChunkCountPlugin.json"),
+	{
+		name: "Limit Chunk Count Plugin",
+		baseDataPath: "options"
+	}
+);
+
+/**
+ * @typedef {object} ChunkCombination
+ * @property {boolean} deleted this is set to true when combination was removed
+ * @property {number} sizeDiff
+ * @property {number} integratedSize
+ * @property {Chunk} a
+ * @property {Chunk} b
+ * @property {number} aIdx
+ * @property {number} bIdx
+ * @property {number} aSize
+ * @property {number} bSize
+ */
+
+/**
+ * @template K, V
+ * @param {Map<K, Set<V>>} map map
+ * @param {K} key key
+ * @param {V} value value
+ */
+const addToSetMap = (map, key, value) => {
+	const set = map.get(key);
+	if (set === undefined) {
+		map.set(key, new Set([value]));
+	} else {
+		set.add(value);
+	}
+};
+
+const PLUGIN_NAME = "LimitChunkCountPlugin";
+
+class LimitChunkCountPlugin {
+	/**
+	 * @param {LimitChunkCountPluginOptions=} options options object
+	 */
+	constructor(options) {
+		validate(options);
+		this.options = /** @type {LimitChunkCountPluginOptions} */ (options);
+	}
+
+	/**
+	 * @param {Compiler} compiler the webpack compiler
+	 * @returns {void}
+	 */
+	apply(compiler) {
+		const options = this.options;
+		compiler.hooks.compilation.tap(PLUGIN_NAME, compilation => {
+			compilation.hooks.optimizeChunks.tap(
+				{
+					name: PLUGIN_NAME,
+					stage: STAGE_ADVANCED
+				},
+				chunks => {
+					const chunkGraph = compilation.chunkGraph;
+					const maxChunks = options.maxChunks;
+					if (!maxChunks) return;
+					if (maxChunks < 1) return;
+					if (compilation.chunks.size <= maxChunks) return;
+
+					let remainingChunksToMerge = compilation.chunks.size - maxChunks;
+
+					// order chunks in a deterministic way
+					const compareChunksWithGraph = compareChunks(chunkGraph);
+					const orderedChunks = Array.from(chunks).sort(compareChunksWithGraph);
+
+					// create a lazy sorted data structure to keep all combinations
+					// this is large. Size = chunks * (chunks - 1) / 2
+					// It uses a multi layer bucket sort plus normal sort in the last layer
+					// It's also lazy so only accessed buckets are sorted
+					/** @type {LazyBucketSortedSet<ChunkCombination, number>} */
+					const combinations = new LazyBucketSortedSet(
+						// Layer 1: ordered by largest size benefit
+						c => c.sizeDiff,
+						(a, b) => b - a,
+
+						// Layer 2: ordered by smallest combined size
+						/**
+						 * @param {ChunkCombination} c combination
+						 * @returns {number} integrated size
+						 */
+						c => c.integratedSize,
+						/**
+						 * @param {number} a a
+						 * @param {number} b b
+						 * @returns {number} result
+						 */
+						(a, b) => a - b,
+
+						// Layer 3: ordered by position difference in orderedChunk (-> to be deterministic)
+						/**
+						 * @param {ChunkCombination} c combination
+						 * @returns {number} position difference
+						 */
+						c => c.bIdx - c.aIdx,
+						/**
+						 * @param {number} a a
+						 * @param {number} b b
+						 * @returns {number} result
+						 */
+						(a, b) => a - b,
+
+						// Layer 4: ordered by position in orderedChunk (-> to be deterministic)
+						/**
+						 * @param {ChunkCombination} a a
+						 * @param {ChunkCombination} b b
+						 * @returns {number} result
+						 */
+						(a, b) => a.bIdx - b.bIdx
+					);
+
+					// we keep a mapping from chunk to all combinations
+					// but this mapping is not kept up-to-date with deletions
+					// so `deleted` flag need to be considered when iterating this
+					/** @type {Map<Chunk, Set<ChunkCombination>>} */
+					const combinationsByChunk = new Map();
+
+					for (const [bIdx, b] of orderedChunks.entries()) {
+						// create combination pairs with size and integrated size
+						for (let aIdx = 0; aIdx < bIdx; aIdx++) {
+							const a = orderedChunks[aIdx];
+							// filter pairs that can not be integrated!
+							if (!chunkGraph.canChunksBeIntegrated(a, b)) continue;
+
+							const integratedSize = chunkGraph.getIntegratedChunksSize(
+								a,
+								b,
+								options
+							);
+
+							const aSize = chunkGraph.getChunkSize(a, options);
+							const bSize = chunkGraph.getChunkSize(b, options);
+							/** @type {ChunkCombination} */
+							const c = {
+								deleted: false,
+								sizeDiff: aSize + bSize - integratedSize,
+								integratedSize,
+								a,
+								b,
+								aIdx,
+								bIdx,
+								aSize,
+								bSize
+							};
+							combinations.add(c);
+							addToSetMap(combinationsByChunk, a, c);
+							addToSetMap(combinationsByChunk, b, c);
+						}
+					}
+
+					// list of modified chunks during this run
+					// combinations affected by this change are skipped to allow
+					// further optimizations
+					/** @type {Set<Chunk>} */
+					const modifiedChunks = new Set();
+
+					let changed = false;
+					loop: while (true) {
+						const combination = combinations.popFirst();
+						if (combination === undefined) break;
+
+						combination.deleted = true;
+						const { a, b, integratedSize } = combination;
+
+						// skip over pair when
+						// one of the already merged chunks is a parent of one of the chunks
+						if (modifiedChunks.size > 0) {
+							const queue = new Set(a.groupsIterable);
+							for (const group of b.groupsIterable) {
+								queue.add(group);
+							}
+							for (const group of queue) {
+								for (const mChunk of modifiedChunks) {
+									if (mChunk !== a && mChunk !== b && mChunk.isInGroup(group)) {
+										// This is a potential pair which needs recalculation
+										// We can't do that now, but it merge before following pairs
+										// so we leave space for it, and consider chunks as modified
+										// just for the worse case
+										remainingChunksToMerge--;
+										if (remainingChunksToMerge <= 0) break loop;
+										modifiedChunks.add(a);
+										modifiedChunks.add(b);
+										continue loop;
+									}
+								}
+								for (const parent of group.parentsIterable) {
+									queue.add(parent);
+								}
+							}
+						}
+
+						// merge the chunks
+						if (chunkGraph.canChunksBeIntegrated(a, b)) {
+							chunkGraph.integrateChunks(a, b);
+							compilation.chunks.delete(b);
+
+							// flag chunk a as modified as further optimization are possible for all children here
+							modifiedChunks.add(a);
+
+							changed = true;
+							remainingChunksToMerge--;
+							if (remainingChunksToMerge <= 0) break;
+
+							// Update all affected combinations
+							// delete all combination with the removed chunk
+							// we will use combinations with the kept chunk instead
+							for (const combination of /** @type {Set<ChunkCombination>} */ (
+								combinationsByChunk.get(a)
+							)) {
+								if (combination.deleted) continue;
+								combination.deleted = true;
+								combinations.delete(combination);
+							}
+
+							// Update combinations with the kept chunk with new sizes
+							for (const combination of /** @type {Set<ChunkCombination>} */ (
+								combinationsByChunk.get(b)
+							)) {
+								if (combination.deleted) continue;
+								if (combination.a === b) {
+									if (!chunkGraph.canChunksBeIntegrated(a, combination.b)) {
+										combination.deleted = true;
+										combinations.delete(combination);
+										continue;
+									}
+									// Update size
+									const newIntegratedSize = chunkGraph.getIntegratedChunksSize(
+										a,
+										combination.b,
+										options
+									);
+									const finishUpdate = combinations.startUpdate(combination);
+									combination.a = a;
+									combination.integratedSize = newIntegratedSize;
+									combination.aSize = integratedSize;
+									combination.sizeDiff =
+										combination.bSize + integratedSize - newIntegratedSize;
+									finishUpdate();
+								} else if (combination.b === b) {
+									if (!chunkGraph.canChunksBeIntegrated(combination.a, a)) {
+										combination.deleted = true;
+										combinations.delete(combination);
+										continue;
+									}
+									// Update size
+									const newIntegratedSize = chunkGraph.getIntegratedChunksSize(
+										combination.a,
+										a,
+										options
+									);
+
+									const finishUpdate = combinations.startUpdate(combination);
+									combination.b = a;
+									combination.integratedSize = newIntegratedSize;
+									combination.bSize = integratedSize;
+									combination.sizeDiff =
+										integratedSize + combination.aSize - newIntegratedSize;
+									finishUpdate();
+								}
+							}
+							combinationsByChunk.set(
+								a,
+								/** @type {Set<ChunkCombination>} */ (
+									combinationsByChunk.get(b)
+								)
+							);
+							combinationsByChunk.delete(b);
+						}
+					}
+					if (changed) return true;
+				}
+			);
+		});
+	}
+}
+module.exports = LimitChunkCountPlugin;