webpack/lib/optimize/OccurrenceOrderPlugin.js

Packs CommonJs/AMD modules for the browser. Allows to split your codebase into multiple bundles, which can be loaded on demand. Support loaders to preprocess files, i.e. json, jsx, es7, css, less, ... and your custom stuff.

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

// TODO webpack 5 remove this plugin
// It has been splitted into separate plugins for modules and chunks
class OccurrenceOrderPlugin {
	constructor(preferEntry) {
		if (preferEntry !== undefined && typeof preferEntry !== "boolean") {
			throw new Error(
				"Argument should be a boolean.\nFor more info on this plugin, see https://webpack.js.org/plugins/"
			);
		}
		this.preferEntry = preferEntry;
	}
	apply(compiler) {
		const preferEntry = this.preferEntry;
		compiler.hooks.compilation.tap("OccurrenceOrderPlugin", compilation => {
			compilation.hooks.optimizeModuleOrder.tap(
				"OccurrenceOrderPlugin",
				modules => {
					const occursInInitialChunksMap = new Map();
					const occursInAllChunksMap = new Map();

					const initialChunkChunkMap = new Map();
					const entryCountMap = new Map();
					for (const m of modules) {
						let initial = 0;
						let entry = 0;
						for (const c of m.chunksIterable) {
							if (c.canBeInitial()) initial++;
							if (c.entryModule === m) entry++;
						}
						initialChunkChunkMap.set(m, initial);
						entryCountMap.set(m, entry);
					}

					const countOccursInEntry = (sum, r) => {
						if (!r.module) {
							return sum;
						}
						return sum + initialChunkChunkMap.get(r.module);
					};
					const countOccurs = (sum, r) => {
						if (!r.module) {
							return sum;
						}
						let factor = 1;
						if (typeof r.dependency.getNumberOfIdOccurrences === "function") {
							factor = r.dependency.getNumberOfIdOccurrences();
						}
						if (factor === 0) {
							return sum;
						}
						return sum + factor * r.module.getNumberOfChunks();
					};

					if (preferEntry) {
						for (const m of modules) {
							const result =
								m.reasons.reduce(countOccursInEntry, 0) +
								initialChunkChunkMap.get(m) +
								entryCountMap.get(m);
							occursInInitialChunksMap.set(m, result);
						}
					}

					const originalOrder = new Map();
					let i = 0;
					for (const m of modules) {
						const result =
							m.reasons.reduce(countOccurs, 0) +
							m.getNumberOfChunks() +
							entryCountMap.get(m);
						occursInAllChunksMap.set(m, result);
						originalOrder.set(m, i++);
					}

					modules.sort((a, b) => {
						if (preferEntry) {
							const aEntryOccurs = occursInInitialChunksMap.get(a);
							const bEntryOccurs = occursInInitialChunksMap.get(b);
							if (aEntryOccurs > bEntryOccurs) return -1;
							if (aEntryOccurs < bEntryOccurs) return 1;
						}
						const aOccurs = occursInAllChunksMap.get(a);
						const bOccurs = occursInAllChunksMap.get(b);
						if (aOccurs > bOccurs) return -1;
						if (aOccurs < bOccurs) return 1;
						const orgA = originalOrder.get(a);
						const orgB = originalOrder.get(b);
						return orgA - orgB;
					});
				}
			);
			compilation.hooks.optimizeChunkOrder.tap(
				"OccurrenceOrderPlugin",
				chunks => {
					const occursInInitialChunksMap = new Map();
					const originalOrder = new Map();

					let i = 0;
					for (const c of chunks) {
						let occurs = 0;
						for (const chunkGroup of c.groupsIterable) {
							for (const parent of chunkGroup.parentsIterable) {
								if (parent.isInitial()) occurs++;
							}
						}
						occursInInitialChunksMap.set(c, occurs);
						originalOrder.set(c, i++);
					}

					chunks.sort((a, b) => {
						const aEntryOccurs = occursInInitialChunksMap.get(a);
						const bEntryOccurs = occursInInitialChunksMap.get(b);
						if (aEntryOccurs > bEntryOccurs) return -1;
						if (aEntryOccurs < bEntryOccurs) return 1;
						const aOccurs = a.getNumberOfGroups();
						const bOccurs = b.getNumberOfGroups();
						if (aOccurs > bOccurs) return -1;
						if (aOccurs < bOccurs) return 1;
						const orgA = originalOrder.get(a);
						const orgB = originalOrder.get(b);
						return orgA - orgB;
					});
				}
			);
		});
	}
}

module.exports = OccurrenceOrderPlugin;