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Packs ECMAScript/CommonJs/AMD modules for the browser. Allows you to split your codebase into multiple bundles, which can be loaded on demand. Supports loaders to preprocess files, i.e. json, jsx, es7, css, less, ... and your custom stuff.
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/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Tobias Koppers @sokra
*/

"use strict";

const { SyncBailHook } = require("tapable");
const { RawSource, CachedSource, CompatSource } = require("webpack-sources");
const Compilation = require("../Compilation");
const WebpackError = require("../WebpackError");
const { compareSelect, compareStrings } = require("../util/comparators");
const createHash = require("../util/createHash");

/** @typedef {import("webpack-sources").Source} Source */
/** @typedef {import("../Cache").Etag} Etag */
/** @typedef {import("../Compilation").AssetInfo} AssetInfo */
/** @typedef {import("../Compiler")} Compiler */
/** @typedef {typeof import("../util/Hash")} Hash */

const EMPTY_SET = new Set();

/**
 * @template T
 * @param {T | T[]} itemOrItems item or items
 * @param {Set} list list
 */
const addToList = (itemOrItems, list) => {
	if (Array.isArray(itemOrItems)) {
		for (const item of itemOrItems) {
			list.add(item);
		}
	} else if (itemOrItems) {
		list.add(itemOrItems);
	}
};

/**
 * @template T
 * @param {T[]} input list
 * @param {function(T): Buffer} fn map function
 * @returns {Buffer[]} buffers without duplicates
 */
const mapAndDeduplicateBuffers = (input, fn) => {
	// Buffer.equals compares size first so this should be efficient enough
	// If it becomes a performance problem we can use a map and group by size
	// instead of looping over all assets.
	const result = [];
	outer: for (const value of input) {
		const buf = fn(value);
		for (const other of result) {
			if (buf.equals(other)) continue outer;
		}
		result.push(buf);
	}
	return result;
};

/**
 * Escapes regular expression metacharacters
 * @param {string} str String to quote
 * @returns {string} Escaped string
 */
const quoteMeta = str => {
	return str.replace(/[-[\]\\/{}()*+?.^$|]/g, "\\$&");
};

const cachedSourceMap = new WeakMap();

/**
 * @param {Source} source source
 * @returns {CachedSource} cached source
 */
const toCachedSource = source => {
	if (source instanceof CachedSource) {
		return source;
	}
	const entry = cachedSourceMap.get(source);
	if (entry !== undefined) return entry;
	const newSource = new CachedSource(CompatSource.from(source));
	cachedSourceMap.set(source, newSource);
	return newSource;
};

/** @typedef {Set} OwnHashes */
/** @typedef {Set} ReferencedHashes */
/** @typedef {Set} Hashes */

/**
 * @typedef {object} AssetInfoForRealContentHash
 * @property {string} name
 * @property {AssetInfo} info
 * @property {Source} source
 * @property {RawSource | undefined} newSource
 * @property {RawSource | undefined} newSourceWithoutOwn
 * @property {string} content
 * @property {OwnHashes | undefined} ownHashes
 * @property {Promise | undefined} contentComputePromise
 * @property {Promise | undefined} contentComputeWithoutOwnPromise
 * @property {ReferencedHashes | undefined} referencedHashes
 * @property {Hashes} hashes
 */

/**
 * @typedef {object} CompilationHooks
 * @property {SyncBailHook<[Buffer[], string], string>} updateHash
 */

/** @type {WeakMap} */
const compilationHooksMap = new WeakMap();

class RealContentHashPlugin {
	/**
	 * @param {Compilation} compilation the compilation
	 * @returns {CompilationHooks} the attached hooks
	 */
	static getCompilationHooks(compilation) {
		if (!(compilation instanceof Compilation)) {
			throw new TypeError(
				"The 'compilation' argument must be an instance of Compilation"
			);
		}
		let hooks = compilationHooksMap.get(compilation);
		if (hooks === undefined) {
			hooks = {
				updateHash: new SyncBailHook(["content", "oldHash"])
			};
			compilationHooksMap.set(compilation, hooks);
		}
		return hooks;
	}

	/**
	 * @param {object} options options object
	 * @param {string | Hash} options.hashFunction the hash function to use
	 * @param {string} options.hashDigest the hash digest to use
	 */
	constructor({ hashFunction, hashDigest }) {
		this._hashFunction = hashFunction;
		this._hashDigest = hashDigest;
	}

	/**
	 * Apply the plugin
	 * @param {Compiler} compiler the compiler instance
	 * @returns {void}
	 */
	apply(compiler) {
		compiler.hooks.compilation.tap("RealContentHashPlugin", compilation => {
			const cacheAnalyse = compilation.getCache(
				"RealContentHashPlugin|analyse"
			);
			const cacheGenerate = compilation.getCache(
				"RealContentHashPlugin|generate"
			);
			const hooks = RealContentHashPlugin.getCompilationHooks(compilation);
			compilation.hooks.processAssets.tapPromise(
				{
					name: "RealContentHashPlugin",
					stage: Compilation.PROCESS_ASSETS_STAGE_OPTIMIZE_HASH
				},
				async () => {
					const assets = compilation.getAssets();
					/** @type {AssetInfoForRealContentHash[]} */
					const assetsWithInfo = [];
					/** @type {Map} */
					const hashToAssets = new Map();
					for (const { source, info, name } of assets) {
						const cachedSource = toCachedSource(source);
						const content = /** @type {string} */ (cachedSource.source());
						/** @type {Hashes} */
						const hashes = new Set();
						addToList(info.contenthash, hashes);
						/** @type {AssetInfoForRealContentHash} */
						const data = {
							name,
							info,
							source: cachedSource,
							newSource: undefined,
							newSourceWithoutOwn: undefined,
							content,
							ownHashes: undefined,
							contentComputePromise: undefined,
							contentComputeWithoutOwnPromise: undefined,
							referencedHashes: undefined,
							hashes
						};
						assetsWithInfo.push(data);
						for (const hash of hashes) {
							const list = hashToAssets.get(hash);
							if (list === undefined) {
								hashToAssets.set(hash, [data]);
							} else {
								list.push(data);
							}
						}
					}
					if (hashToAssets.size === 0) return;
					const hashRegExp = new RegExp(
						Array.from(hashToAssets.keys(), quoteMeta).join("|"),
						"g"
					);
					await Promise.all(
						assetsWithInfo.map(async asset => {
							const { name, source, content, hashes } = asset;
							if (Buffer.isBuffer(content)) {
								asset.referencedHashes = EMPTY_SET;
								asset.ownHashes = EMPTY_SET;
								return;
							}
							const etag = cacheAnalyse.mergeEtags(
								cacheAnalyse.getLazyHashedEtag(source),
								Array.from(hashes).join("|")
							);
							[asset.referencedHashes, asset.ownHashes] =
								await cacheAnalyse.providePromise(name, etag, () => {
									const referencedHashes = new Set();
									let ownHashes = new Set();
									const inContent = content.match(hashRegExp);
									if (inContent) {
										for (const hash of inContent) {
											if (hashes.has(hash)) {
												ownHashes.add(hash);
												continue;
											}
											referencedHashes.add(hash);
										}
									}
									return [referencedHashes, ownHashes];
								});
						})
					);
					/**
					 * @param {string} hash the hash
					 * @returns {undefined | ReferencedHashes} the referenced hashes
					 */
					const getDependencies = hash => {
						const assets = hashToAssets.get(hash);
						if (!assets) {
							const referencingAssets = assetsWithInfo.filter(asset =>
								/** @type {ReferencedHashes} */ (asset.referencedHashes).has(
									hash
								)
							);
							const err = new WebpackError(`RealContentHashPlugin
Some kind of unexpected caching problem occurred.
An asset was cached with a reference to another asset (${hash}) that's not in the compilation anymore.
Either the asset was incorrectly cached, or the referenced asset should also be restored from cache.
Referenced by:
${referencingAssets
	.map(a => {
		const match = new RegExp(`.{0,20}${quoteMeta(hash)}.{0,20}`).exec(
			a.content
		);
		return ` - ${a.name}: ...${match ? match[0] : "???"}...`;
	})
	.join("\n")}`);
							compilation.errors.push(err);
							return undefined;
						}
						const hashes = new Set();
						for (const { referencedHashes, ownHashes } of assets) {
							if (!(/** @type {OwnHashes} */ (ownHashes).has(hash))) {
								for (const hash of /** @type {OwnHashes} */ (ownHashes)) {
									hashes.add(hash);
								}
							}
							for (const hash of /** @type {ReferencedHashes} */ (
								referencedHashes
							)) {
								hashes.add(hash);
							}
						}
						return hashes;
					};
					/**
					 * @param {string} hash the hash
					 * @returns {string} the hash info
					 */
					const hashInfo = hash => {
						const assets = hashToAssets.get(hash);
						return `${hash} (${Array.from(
							/** @type {AssetInfoForRealContentHash[]} */ (assets),
							a => a.name
						)})`;
					};
					const hashesInOrder = new Set();
					for (const hash of hashToAssets.keys()) {
						/**
						 * @param {string} hash the hash
						 * @param {Set} stack stack of hashes
						 */
						const add = (hash, stack) => {
							const deps = getDependencies(hash);
							if (!deps) return;
							stack.add(hash);
							for (const dep of deps) {
								if (hashesInOrder.has(dep)) continue;
								if (stack.has(dep)) {
									throw new Error(
										`Circular hash dependency ${Array.from(
											stack,
											hashInfo
										).join(" -> ")} -> ${hashInfo(dep)}`
									);
								}
								add(dep, stack);
							}
							hashesInOrder.add(hash);
							stack.delete(hash);
						};
						if (hashesInOrder.has(hash)) continue;
						add(hash, new Set());
					}
					const hashToNewHash = new Map();
					/**
					 * @param {AssetInfoForRealContentHash} asset asset info
					 * @returns {Etag} etag
					 */
					const getEtag = asset =>
						cacheGenerate.mergeEtags(
							cacheGenerate.getLazyHashedEtag(asset.source),
							Array.from(
								/** @type {ReferencedHashes} */ (asset.referencedHashes),
								hash => hashToNewHash.get(hash)
							).join("|")
						);
					/**
					 * @param {AssetInfoForRealContentHash} asset asset info
					 * @returns {Promise}
					 */
					const computeNewContent = asset => {
						if (asset.contentComputePromise) return asset.contentComputePromise;
						return (asset.contentComputePromise = (async () => {
							if (
								/** @type {OwnHashes} */ (asset.ownHashes).size > 0 ||
								Array.from(
									/** @type {ReferencedHashes} */
									(asset.referencedHashes)
								).some(hash => hashToNewHash.get(hash) !== hash)
							) {
								const identifier = asset.name;
								const etag = getEtag(asset);
								asset.newSource = await cacheGenerate.providePromise(
									identifier,
									etag,
									() => {
										const newContent = asset.content.replace(hashRegExp, hash =>
											hashToNewHash.get(hash)
										);
										return new RawSource(newContent);
									}
								);
							}
						})());
					};
					/**
					 * @param {AssetInfoForRealContentHash} asset asset info
					 * @returns {Promise}
					 */
					const computeNewContentWithoutOwn = asset => {
						if (asset.contentComputeWithoutOwnPromise)
							return asset.contentComputeWithoutOwnPromise;
						return (asset.contentComputeWithoutOwnPromise = (async () => {
							if (
								/** @type {OwnHashes} */ (asset.ownHashes).size > 0 ||
								Array.from(
									/** @type {ReferencedHashes} */
									(asset.referencedHashes)
								).some(hash => hashToNewHash.get(hash) !== hash)
							) {
								const identifier = asset.name + "|without-own";
								const etag = getEtag(asset);
								asset.newSourceWithoutOwn = await cacheGenerate.providePromise(
									identifier,
									etag,
									() => {
										const newContent = asset.content.replace(
											hashRegExp,
											hash => {
												if (
													/** @type {OwnHashes} */ (asset.ownHashes).has(hash)
												) {
													return "";
												}
												return hashToNewHash.get(hash);
											}
										);
										return new RawSource(newContent);
									}
								);
							}
						})());
					};
					const comparator = compareSelect(a => a.name, compareStrings);
					for (const oldHash of hashesInOrder) {
						const assets =
							/** @type {AssetInfoForRealContentHash[]} */
							(hashToAssets.get(oldHash));
						assets.sort(comparator);
						await Promise.all(
							assets.map(asset =>
								/** @type {OwnHashes} */ (asset.ownHashes).has(oldHash)
									? computeNewContentWithoutOwn(asset)
									: computeNewContent(asset)
							)
						);
						const assetsContent = mapAndDeduplicateBuffers(assets, asset => {
							if (/** @type {OwnHashes} */ (asset.ownHashes).has(oldHash)) {
								return asset.newSourceWithoutOwn
									? asset.newSourceWithoutOwn.buffer()
									: asset.source.buffer();
							} else {
								return asset.newSource
									? asset.newSource.buffer()
									: asset.source.buffer();
							}
						});
						let newHash = hooks.updateHash.call(assetsContent, oldHash);
						if (!newHash) {
							const hash = createHash(this._hashFunction);
							if (compilation.outputOptions.hashSalt) {
								hash.update(compilation.outputOptions.hashSalt);
							}
							for (const content of assetsContent) {
								hash.update(content);
							}
							const digest = hash.digest(this._hashDigest);
							newHash = /** @type {string} */ (digest.slice(0, oldHash.length));
						}
						hashToNewHash.set(oldHash, newHash);
					}
					await Promise.all(
						assetsWithInfo.map(async asset => {
							await computeNewContent(asset);
							const newName = asset.name.replace(hashRegExp, hash =>
								hashToNewHash.get(hash)
							);

							const infoUpdate = {};
							const hash = asset.info.contenthash;
							infoUpdate.contenthash = Array.isArray(hash)
								? hash.map(hash => hashToNewHash.get(hash))
								: hashToNewHash.get(hash);

							if (asset.newSource !== undefined) {
								compilation.updateAsset(
									asset.name,
									asset.newSource,
									infoUpdate
								);
							} else {
								compilation.updateAsset(asset.name, asset.source, infoUpdate);
							}

							if (asset.name !== newName) {
								compilation.renameAsset(asset.name, newName);
							}
						})
					);
				}
			);
		});
	}
}

module.exports = RealContentHashPlugin;