webpack/lib/asset/AssetGenerator.js

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.

/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Sergey Melyukov @smelukov
*/

"use strict";

const mimeTypes = require("mime-types");
const path = require("path");
const { RawSource } = require("webpack-sources");
const ConcatenationScope = require("../ConcatenationScope");
const Generator = require("../Generator");
const {
	NO_TYPES,
	ASSET_TYPES,
	ASSET_AND_JS_TYPES,
	ASSET_AND_JS_AND_CSS_URL_TYPES,
	ASSET_AND_CSS_URL_TYPES,
	JS_TYPES,
	JS_AND_CSS_URL_TYPES,
	CSS_URL_TYPES
} = require("../ModuleSourceTypesConstants");
const { ASSET_MODULE_TYPE } = require("../ModuleTypeConstants");
const RuntimeGlobals = require("../RuntimeGlobals");
const CssUrlDependency = require("../dependencies/CssUrlDependency");
const createHash = require("../util/createHash");
const { makePathsRelative } = require("../util/identifier");
const nonNumericOnlyHash = require("../util/nonNumericOnlyHash");

/** @typedef {import("webpack-sources").Source} Source */
/** @typedef {import("../../declarations/WebpackOptions").AssetGeneratorDataUrlOptions} AssetGeneratorDataUrlOptions */
/** @typedef {import("../../declarations/WebpackOptions").AssetGeneratorOptions} AssetGeneratorOptions */
/** @typedef {import("../../declarations/WebpackOptions").AssetModuleFilename} AssetModuleFilename */
/** @typedef {import("../../declarations/WebpackOptions").AssetModuleOutputPath} AssetModuleOutputPath */
/** @typedef {import("../../declarations/WebpackOptions").AssetResourceGeneratorOptions} AssetResourceGeneratorOptions */
/** @typedef {import("../../declarations/WebpackOptions").RawPublicPath} RawPublicPath */
/** @typedef {import("../ChunkGraph")} ChunkGraph */
/** @typedef {import("../Compilation")} Compilation */
/** @typedef {import("../Compilation").AssetInfo} AssetInfo */
/** @typedef {import("../Compilation").InterpolatedPathAndAssetInfo} InterpolatedPathAndAssetInfo */
/** @typedef {import("../Compiler")} Compiler */
/** @typedef {import("../Generator").GenerateContext} GenerateContext */
/** @typedef {import("../Generator").UpdateHashContext} UpdateHashContext */
/** @typedef {import("../Module")} Module */
/** @typedef {import("../Module").BuildInfo} BuildInfo */
/** @typedef {import("../Module").BuildMeta} BuildMeta */
/** @typedef {import("../Module").ConcatenationBailoutReasonContext} ConcatenationBailoutReasonContext */
/** @typedef {import("../Module").SourceTypes} SourceTypes */
/** @typedef {import("../ModuleGraph")} ModuleGraph */
/** @typedef {import("../NormalModule")} NormalModule */
/** @typedef {import("../RuntimeTemplate")} RuntimeTemplate */
/** @typedef {import("../TemplatedPathPlugin").TemplatePath} TemplatePath */
/** @typedef {import("../util/Hash")} Hash */
/** @typedef {import("../util/createHash").Algorithm} Algorithm */
/** @typedef {import("../util/runtime").RuntimeSpec} RuntimeSpec */

/**
 * @template T
 * @template U
 * @param {string | Array<T> | Set<T> | undefined} a a
 * @param {string | Array<U> | Set<U> | undefined} b b
 * @returns {Array<T> & Array<U>} array
 */
const mergeMaybeArrays = (a, b) => {
	const set = new Set();
	if (Array.isArray(a)) for (const item of a) set.add(item);
	else set.add(a);
	if (Array.isArray(b)) for (const item of b) set.add(item);
	else set.add(b);
	return Array.from(set);
};

/**
 * @param {AssetInfo} a a
 * @param {AssetInfo} b b
 * @returns {AssetInfo} object
 */
const mergeAssetInfo = (a, b) => {
	/** @type {AssetInfo} */
	const result = { ...a, ...b };
	for (const key of Object.keys(a)) {
		if (key in b) {
			if (a[key] === b[key]) continue;
			switch (key) {
				case "fullhash":
				case "chunkhash":
				case "modulehash":
				case "contenthash":
					result[key] = mergeMaybeArrays(a[key], b[key]);
					break;
				case "immutable":
				case "development":
				case "hotModuleReplacement":
				case "javascriptModule":
					result[key] = a[key] || b[key];
					break;
				case "related":
					result[key] = mergeRelatedInfo(
						/** @type {NonNullable<AssetInfo["related"]>} */
						(a[key]),
						/** @type {NonNullable<AssetInfo["related"]>} */
						(b[key])
					);
					break;
				default:
					throw new Error(`Can't handle conflicting asset info for ${key}`);
			}
		}
	}
	return result;
};

/**
 * @param {NonNullable<AssetInfo["related"]>} a a
 * @param {NonNullable<AssetInfo["related"]>} b b
 * @returns {NonNullable<AssetInfo["related"]>} object
 */
const mergeRelatedInfo = (a, b) => {
	const result = { ...a, ...b };
	for (const key of Object.keys(a)) {
		if (key in b) {
			if (a[key] === b[key]) continue;
			result[key] = mergeMaybeArrays(a[key], b[key]);
		}
	}
	return result;
};

/**
 * @param {"base64" | false} encoding encoding
 * @param {Source} source source
 * @returns {string} encoded data
 */
const encodeDataUri = (encoding, source) => {
	/** @type {string | undefined} */
	let encodedContent;

	switch (encoding) {
		case "base64": {
			encodedContent = source.buffer().toString("base64");
			break;
		}
		case false: {
			const content = source.source();

			if (typeof content !== "string") {
				encodedContent = content.toString("utf-8");
			}

			encodedContent = encodeURIComponent(
				/** @type {string} */
				(encodedContent)
			).replace(
				/[!'()*]/g,
				character =>
					`%${/** @type {number} */ (character.codePointAt(0)).toString(16)}`
			);
			break;
		}
		default:
			throw new Error(`Unsupported encoding '${encoding}'`);
	}

	return encodedContent;
};

/**
 * @param {string} encoding encoding
 * @param {string} content content
 * @returns {Buffer} decoded content
 */
const decodeDataUriContent = (encoding, content) => {
	const isBase64 = encoding === "base64";

	if (isBase64) {
		return Buffer.from(content, "base64");
	}

	// If we can't decode return the original body
	try {
		return Buffer.from(decodeURIComponent(content), "ascii");
	} catch (_) {
		return Buffer.from(content, "ascii");
	}
};

const DEFAULT_ENCODING = "base64";

class AssetGenerator extends Generator {
	/**
	 * @param {ModuleGraph} moduleGraph the module graph
	 * @param {AssetGeneratorOptions["dataUrl"]=} dataUrlOptions the options for the data url
	 * @param {AssetModuleFilename=} filename override for output.assetModuleFilename
	 * @param {RawPublicPath=} publicPath override for output.assetModulePublicPath
	 * @param {AssetModuleOutputPath=} outputPath the output path for the emitted file which is not included in the runtime import
	 * @param {boolean=} emit generate output asset
	 */
	constructor(
		moduleGraph,
		dataUrlOptions,
		filename,
		publicPath,
		outputPath,
		emit
	) {
		super();
		this.dataUrlOptions = dataUrlOptions;
		this.filename = filename;
		this.publicPath = publicPath;
		this.outputPath = outputPath;
		this.emit = emit;
		this._moduleGraph = moduleGraph;
	}

	/**
	 * @param {NormalModule} module module
	 * @param {RuntimeTemplate} runtimeTemplate runtime template
	 * @returns {string} source file name
	 */
	static getSourceFileName(module, runtimeTemplate) {
		return makePathsRelative(
			runtimeTemplate.compilation.compiler.context,
			module.matchResource || module.resource,
			runtimeTemplate.compilation.compiler.root
		).replace(/^\.\//, "");
	}

	/**
	 * @param {NormalModule} module module
	 * @param {RuntimeTemplate} runtimeTemplate runtime template
	 * @returns {[string, string]} return full hash and non-numeric full hash
	 */
	static getFullContentHash(module, runtimeTemplate) {
		const hash = createHash(
			/** @type {Algorithm} */
			(runtimeTemplate.outputOptions.hashFunction)
		);

		if (runtimeTemplate.outputOptions.hashSalt) {
			hash.update(runtimeTemplate.outputOptions.hashSalt);
		}

		const source = module.originalSource();

		if (source) {
			hash.update(source.buffer());
		}

		if (module.error) {
			hash.update(module.error.toString());
		}

		const fullContentHash = /** @type {string} */ (
			hash.digest(runtimeTemplate.outputOptions.hashDigest)
		);

		/** @type {string} */
		const contentHash = nonNumericOnlyHash(
			fullContentHash,
			/** @type {number} */
			(runtimeTemplate.outputOptions.hashDigestLength)
		);

		return [fullContentHash, contentHash];
	}

	/**
	 * @param {NormalModule} module module for which the code should be generated
	 * @param {Pick<AssetResourceGeneratorOptions, "filename" | "outputPath">} generatorOptions generator options
	 * @param {{ runtime: RuntimeSpec, runtimeTemplate: RuntimeTemplate, chunkGraph: ChunkGraph }} generateContext context for generate
	 * @param {string} contentHash the content hash
	 * @returns {{ filename: string, originalFilename: string, assetInfo: AssetInfo }} info
	 */
	static getFilenameWithInfo(
		module,
		generatorOptions,
		{ runtime, runtimeTemplate, chunkGraph },
		contentHash
	) {
		const assetModuleFilename =
			generatorOptions.filename ||
			/** @type {AssetModuleFilename} */
			(runtimeTemplate.outputOptions.assetModuleFilename);

		const sourceFilename = AssetGenerator.getSourceFileName(
			module,
			runtimeTemplate
		);
		let { path: filename, info: assetInfo } =
			runtimeTemplate.compilation.getAssetPathWithInfo(assetModuleFilename, {
				module,
				runtime,
				filename: sourceFilename,
				chunkGraph,
				contentHash
			});

		const originalFilename = filename;

		if (generatorOptions.outputPath) {
			const { path: outputPath, info } =
				runtimeTemplate.compilation.getAssetPathWithInfo(
					generatorOptions.outputPath,
					{
						module,
						runtime,
						filename: sourceFilename,
						chunkGraph,
						contentHash
					}
				);
			filename = path.posix.join(outputPath, filename);
			assetInfo = mergeAssetInfo(assetInfo, info);
		}

		return { originalFilename, filename, assetInfo };
	}

	/**
	 * @param {NormalModule} module module for which the code should be generated
	 * @param {Pick<AssetResourceGeneratorOptions, "publicPath">} generatorOptions generator options
	 * @param {GenerateContext} generateContext context for generate
	 * @param {string} filename the filename
	 * @param {AssetInfo} assetInfo the asset info
	 * @param {string} contentHash the content hash
	 * @returns {{ assetPath: string, assetInfo: AssetInfo }} asset path and info
	 */
	static getAssetPathWithInfo(
		module,
		generatorOptions,
		{ runtime, runtimeTemplate, type, chunkGraph, runtimeRequirements },
		filename,
		assetInfo,
		contentHash
	) {
		const sourceFilename = AssetGenerator.getSourceFileName(
			module,
			runtimeTemplate
		);

		let assetPath;

		if (generatorOptions.publicPath !== undefined && type === "javascript") {
			const { path, info } = runtimeTemplate.compilation.getAssetPathWithInfo(
				generatorOptions.publicPath,
				{
					module,
					runtime,
					filename: sourceFilename,
					chunkGraph,
					contentHash
				}
			);
			assetInfo = mergeAssetInfo(assetInfo, info);
			assetPath = JSON.stringify(path + filename);
		} else if (
			generatorOptions.publicPath !== undefined &&
			type === "css-url"
		) {
			const { path, info } = runtimeTemplate.compilation.getAssetPathWithInfo(
				generatorOptions.publicPath,
				{
					module,
					runtime,
					filename: sourceFilename,
					chunkGraph,
					contentHash
				}
			);
			assetInfo = mergeAssetInfo(assetInfo, info);
			assetPath = path + filename;
		} else if (type === "javascript") {
			// add __webpack_require__.p
			runtimeRequirements.add(RuntimeGlobals.publicPath);
			assetPath = runtimeTemplate.concatenation(
				{ expr: RuntimeGlobals.publicPath },
				filename
			);
		} else if (type === "css-url") {
			const compilation = runtimeTemplate.compilation;
			const path =
				compilation.outputOptions.publicPath === "auto"
					? CssUrlDependency.PUBLIC_PATH_AUTO
					: compilation.getAssetPath(
							/** @type {TemplatePath} */
							(compilation.outputOptions.publicPath),
							{
								hash: compilation.hash
							}
						);

			assetPath = path + filename;
		}

		return {
			// eslint-disable-next-line object-shorthand
			assetPath: /** @type {string} */ (assetPath),
			assetInfo: { sourceFilename, ...assetInfo }
		};
	}

	/**
	 * @param {NormalModule} module module for which the bailout reason should be determined
	 * @param {ConcatenationBailoutReasonContext} context context
	 * @returns {string | undefined} reason why this module can't be concatenated, undefined when it can be concatenated
	 */
	getConcatenationBailoutReason(module, context) {
		return undefined;
	}

	/**
	 * @param {NormalModule} module module
	 * @returns {string} mime type
	 */
	getMimeType(module) {
		if (typeof this.dataUrlOptions === "function") {
			throw new Error(
				"This method must not be called when dataUrlOptions is a function"
			);
		}

		/** @type {string | boolean | undefined} */
		let mimeType =
			/** @type {AssetGeneratorDataUrlOptions} */
			(this.dataUrlOptions).mimetype;
		if (mimeType === undefined) {
			const ext = path.extname(
				/** @type {string} */
				(module.nameForCondition())
			);
			if (
				module.resourceResolveData &&
				module.resourceResolveData.mimetype !== undefined
			) {
				mimeType =
					module.resourceResolveData.mimetype +
					module.resourceResolveData.parameters;
			} else if (ext) {
				mimeType = mimeTypes.lookup(ext);

				if (typeof mimeType !== "string") {
					throw new Error(
						"DataUrl can't be generated automatically, " +
							`because there is no mimetype for "${ext}" in mimetype database. ` +
							'Either pass a mimetype via "generator.mimetype" or ' +
							'use type: "asset/resource" to create a resource file instead of a DataUrl'
					);
				}
			}
		}

		if (typeof mimeType !== "string") {
			throw new Error(
				"DataUrl can't be generated automatically. " +
					'Either pass a mimetype via "generator.mimetype" or ' +
					'use type: "asset/resource" to create a resource file instead of a DataUrl'
			);
		}

		return /** @type {string} */ (mimeType);
	}

	/**
	 * @param {NormalModule} module module for which the code should be generated
	 * @returns {string} DataURI
	 */
	generateDataUri(module) {
		const source = /** @type {Source} */ (module.originalSource());

		let encodedSource;

		if (typeof this.dataUrlOptions === "function") {
			encodedSource = this.dataUrlOptions.call(null, source.source(), {
				filename: module.matchResource || module.resource,
				module
			});
		} else {
			/** @type {"base64" | false | undefined} */
			let encoding =
				/** @type {AssetGeneratorDataUrlOptions} */
				(this.dataUrlOptions).encoding;
			if (
				encoding === undefined &&
				module.resourceResolveData &&
				module.resourceResolveData.encoding !== undefined
			) {
				encoding = module.resourceResolveData.encoding;
			}
			if (encoding === undefined) {
				encoding = DEFAULT_ENCODING;
			}
			const mimeType = this.getMimeType(module);

			let encodedContent;

			if (
				module.resourceResolveData &&
				module.resourceResolveData.encoding === encoding &&
				decodeDataUriContent(
					module.resourceResolveData.encoding,
					module.resourceResolveData.encodedContent
				).equals(source.buffer())
			) {
				encodedContent = module.resourceResolveData.encodedContent;
			} else {
				encodedContent = encodeDataUri(encoding, source);
			}

			encodedSource = `data:${mimeType}${
				encoding ? `;${encoding}` : ""
			},${encodedContent}`;
		}

		return encodedSource;
	}

	/**
	 * @param {NormalModule} module module for which the code should be generated
	 * @param {GenerateContext} generateContext context for generate
	 * @returns {Source | null} generated code
	 */
	generate(module, generateContext) {
		const {
			type,
			getData,
			runtimeTemplate,
			runtimeRequirements,
			concatenationScope
		} = generateContext;

		let content;

		const needContent = type === "javascript" || type === "css-url";

		const data = getData ? getData() : undefined;

		if (
			/** @type {BuildInfo} */
			(module.buildInfo).dataUrl &&
			needContent
		) {
			const encodedSource = this.generateDataUri(module);
			content =
				type === "javascript" ? JSON.stringify(encodedSource) : encodedSource;

			if (data) {
				data.set("url", { [type]: content, ...data.get("url") });
			}
		} else {
			const [fullContentHash, contentHash] = AssetGenerator.getFullContentHash(
				module,
				runtimeTemplate
			);

			if (data) {
				data.set("fullContentHash", fullContentHash);
				data.set("contentHash", contentHash);
			}

			/** @type {BuildInfo} */
			(module.buildInfo).fullContentHash = fullContentHash;

			const { originalFilename, filename, assetInfo } =
				AssetGenerator.getFilenameWithInfo(
					module,
					{ filename: this.filename, outputPath: this.outputPath },
					generateContext,
					contentHash
				);

			if (data) {
				data.set("filename", filename);
			}

			let { assetPath, assetInfo: newAssetInfo } =
				AssetGenerator.getAssetPathWithInfo(
					module,
					{ publicPath: this.publicPath },
					generateContext,
					originalFilename,
					assetInfo,
					contentHash
				);

			if (data && (type === "javascript" || type === "css-url")) {
				data.set("url", { [type]: assetPath, ...data.get("url") });
			}

			if (data && data.get("assetInfo")) {
				newAssetInfo = mergeAssetInfo(data.get("assetInfo"), newAssetInfo);
			}

			if (data) {
				data.set("assetInfo", newAssetInfo);
			}

			// Due to code generation caching module.buildInfo.XXX can't used to store such information
			// It need to be stored in the code generation results instead, where it's cached too
			// TODO webpack 6 For back-compat reasons we also store in on module.buildInfo
			/** @type {BuildInfo} */
			(module.buildInfo).filename = filename;

			/** @type {BuildInfo} */
			(module.buildInfo).assetInfo = newAssetInfo;

			content = assetPath;
		}

		if (type === "javascript") {
			if (concatenationScope) {
				concatenationScope.registerNamespaceExport(
					ConcatenationScope.NAMESPACE_OBJECT_EXPORT
				);

				return new RawSource(
					`${runtimeTemplate.supportsConst() ? "const" : "var"} ${
						ConcatenationScope.NAMESPACE_OBJECT_EXPORT
					} = ${content};`
				);
			}

			runtimeRequirements.add(RuntimeGlobals.module);

			return new RawSource(`${RuntimeGlobals.module}.exports = ${content};`);
		} else if (type === "css-url") {
			return null;
		}

		return /** @type {Source} */ (module.originalSource());
	}

	/**
	 * @param {Error} error the error
	 * @param {NormalModule} module module for which the code should be generated
	 * @param {GenerateContext} generateContext context for generate
	 * @returns {Source | null} generated code
	 */
	generateError(error, module, generateContext) {
		switch (generateContext.type) {
			case "asset": {
				return new RawSource(error.message);
			}
			case "javascript": {
				return new RawSource(
					`throw new Error(${JSON.stringify(error.message)});`
				);
			}
			default:
				return null;
		}
	}

	/**
	 * @param {NormalModule} module fresh module
	 * @returns {SourceTypes} available types (do not mutate)
	 */
	getTypes(module) {
		const sourceTypes = new Set();
		const connections = this._moduleGraph.getIncomingConnections(module);

		for (const connection of connections) {
			if (!connection.originModule) {
				continue;
			}

			sourceTypes.add(connection.originModule.type.split("/")[0]);
		}

		if ((module.buildInfo && module.buildInfo.dataUrl) || this.emit === false) {
			if (sourceTypes) {
				if (sourceTypes.has("javascript") && sourceTypes.has("css")) {
					return JS_AND_CSS_URL_TYPES;
				} else if (sourceTypes.has("javascript")) {
					return JS_TYPES;
				} else if (sourceTypes.has("css")) {
					return CSS_URL_TYPES;
				}
			}

			return NO_TYPES;
		}

		if (sourceTypes) {
			if (sourceTypes.has("javascript") && sourceTypes.has("css")) {
				return ASSET_AND_JS_AND_CSS_URL_TYPES;
			} else if (sourceTypes.has("javascript")) {
				return ASSET_AND_JS_TYPES;
			} else if (sourceTypes.has("css")) {
				return ASSET_AND_CSS_URL_TYPES;
			}
		}

		return ASSET_TYPES;
	}

	/**
	 * @param {NormalModule} module the module
	 * @param {string=} type source type
	 * @returns {number} estimate size of the module
	 */
	getSize(module, type) {
		switch (type) {
			case ASSET_MODULE_TYPE: {
				const originalSource = module.originalSource();

				if (!originalSource) {
					return 0;
				}

				return originalSource.size();
			}
			default:
				if (module.buildInfo && module.buildInfo.dataUrl) {
					const originalSource = module.originalSource();

					if (!originalSource) {
						return 0;
					}

					// roughly for data url
					// Example: m.exports="data:image/png;base64,ag82/f+2=="
					// 4/3 = base64 encoding
					// 34 = ~ data url header + footer + rounding
					return originalSource.size() * 1.34 + 36;
				}
				// it's only estimated so this number is probably fine
				// Example: m.exports=r.p+"0123456789012345678901.ext"
				return 42;
		}
	}

	/**
	 * @param {Hash} hash hash that will be modified
	 * @param {UpdateHashContext} updateHashContext context for updating hash
	 */
	updateHash(hash, updateHashContext) {
		const { module } = updateHashContext;

		if (
			/** @type {BuildInfo} */
			(module.buildInfo).dataUrl
		) {
			hash.update("data-url");
			// this.dataUrlOptions as function should be pure and only depend on input source and filename
			// therefore it doesn't need to be hashed
			if (typeof this.dataUrlOptions === "function") {
				const ident = /** @type {{ ident?: string }} */ (this.dataUrlOptions)
					.ident;
				if (ident) hash.update(ident);
			} else {
				const dataUrlOptions =
					/** @type {AssetGeneratorDataUrlOptions} */
					(this.dataUrlOptions);
				if (
					dataUrlOptions.encoding &&
					dataUrlOptions.encoding !== DEFAULT_ENCODING
				) {
					hash.update(dataUrlOptions.encoding);
				}
				if (dataUrlOptions.mimetype) hash.update(dataUrlOptions.mimetype);
				// computed mimetype depends only on module filename which is already part of the hash
			}
		} else {
			hash.update("resource");

			const { module, chunkGraph, runtime } = updateHashContext;
			const runtimeTemplate =
				/** @type {NonNullable<UpdateHashContext["runtimeTemplate"]>} */
				(updateHashContext.runtimeTemplate);

			const pathData = {
				module,
				runtime,
				filename: AssetGenerator.getSourceFileName(module, runtimeTemplate),
				chunkGraph,
				contentHash: runtimeTemplate.contentHashReplacement
			};

			if (typeof this.publicPath === "function") {
				hash.update("path");
				const assetInfo = {};
				hash.update(this.publicPath(pathData, assetInfo));
				hash.update(JSON.stringify(assetInfo));
			} else if (this.publicPath) {
				hash.update("path");
				hash.update(this.publicPath);
			} else {
				hash.update("no-path");
			}

			const assetModuleFilename =
				this.filename ||
				/** @type {AssetModuleFilename} */
				(runtimeTemplate.outputOptions.assetModuleFilename);
			const { path: filename, info } =
				runtimeTemplate.compilation.getAssetPathWithInfo(
					assetModuleFilename,
					pathData
				);
			hash.update(filename);
			hash.update(JSON.stringify(info));
		}
	}
}

module.exports = AssetGenerator;