webpack/lib/ModuleInfoHeaderPlugin.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";

const { ConcatSource } = require("webpack-sources");
const { UsageState } = require("./ExportsInfo");
const Template = require("./Template");
const JavascriptModulesPlugin = require("./javascript/JavascriptModulesPlugin");

/** @typedef {import("./Compiler")} Compiler */
/** @typedef {import("./ExportsInfo")} ExportsInfo */
/** @typedef {import("./ExportsInfo").ExportInfo} ExportInfo */
/** @typedef {import("./ModuleGraph")} ModuleGraph */
/** @typedef {import("./ModuleTemplate")} ModuleTemplate */
/** @typedef {import("./RequestShortener")} RequestShortener */

const joinIterableWithComma = iterable => {
	// This is more performant than Array.from().join(", ")
	// as it doesn't create an array
	let str = "";
	let first = true;
	for (const item of iterable) {
		if (first) {
			first = false;
		} else {
			str += ", ";
		}
		str += item;
	}
	return str;
};

/**
 * @param {ConcatSource} source output
 * @param {string} indent spacing
 * @param {ExportsInfo} exportsInfo data
 * @param {ModuleGraph} moduleGraph moduleGraph
 * @param {RequestShortener} requestShortener requestShortener
 * @param {Set<ExportInfo>} alreadyPrinted deduplication set
 * @returns {void}
 */
const printExportsInfoToSource = (
	source,
	indent,
	exportsInfo,
	moduleGraph,
	requestShortener,
	alreadyPrinted = new Set()
) => {
	const otherExportsInfo = exportsInfo.otherExportsInfo;

	let alreadyPrintedExports = 0;

	// determine exports to print
	const printedExports = [];
	for (const exportInfo of exportsInfo.orderedExports) {
		if (!alreadyPrinted.has(exportInfo)) {
			alreadyPrinted.add(exportInfo);
			printedExports.push(exportInfo);
		} else {
			alreadyPrintedExports++;
		}
	}
	let showOtherExports = false;
	if (!alreadyPrinted.has(otherExportsInfo)) {
		alreadyPrinted.add(otherExportsInfo);
		showOtherExports = true;
	} else {
		alreadyPrintedExports++;
	}

	// print the exports
	for (const exportInfo of printedExports) {
		const target = exportInfo.getTarget(moduleGraph);
		source.add(
			Template.toComment(
				`${indent}export ${JSON.stringify(exportInfo.name).slice(
					1,
					-1
				)} [${exportInfo.getProvidedInfo()}] [${exportInfo.getUsedInfo()}] [${exportInfo.getRenameInfo()}]${
					target
						? ` -> ${target.module.readableIdentifier(requestShortener)}${
								target.export
									? ` .${target.export
											.map(e => JSON.stringify(e).slice(1, -1))
											.join(".")}`
									: ""
						  }`
						: ""
				}`
			) + "\n"
		);
		if (exportInfo.exportsInfo) {
			printExportsInfoToSource(
				source,
				indent + "  ",
				exportInfo.exportsInfo,
				moduleGraph,
				requestShortener,
				alreadyPrinted
			);
		}
	}

	if (alreadyPrintedExports) {
		source.add(
			Template.toComment(
				`${indent}... (${alreadyPrintedExports} already listed exports)`
			) + "\n"
		);
	}

	if (showOtherExports) {
		const target = otherExportsInfo.getTarget(moduleGraph);
		if (
			target ||
			otherExportsInfo.provided !== false ||
			otherExportsInfo.getUsed(undefined) !== UsageState.Unused
		) {
			const title =
				printedExports.length > 0 || alreadyPrintedExports > 0
					? "other exports"
					: "exports";
			source.add(
				Template.toComment(
					`${indent}${title} [${otherExportsInfo.getProvidedInfo()}] [${otherExportsInfo.getUsedInfo()}]${
						target
							? ` -> ${target.module.readableIdentifier(requestShortener)}`
							: ""
					}`
				) + "\n"
			);
		}
	}
};

class ModuleInfoHeaderPlugin {
	/**
	 * @param {Compiler} compiler the compiler
	 * @returns {void}
	 */
	apply(compiler) {
		compiler.hooks.compilation.tap("ModuleInfoHeaderPlugin", compilation => {
			const hooks = JavascriptModulesPlugin.getCompilationHooks(compilation);
			hooks.renderModulePackage.tap(
				"ModuleInfoHeaderPlugin",
				(
					moduleSource,
					module,
					{ chunk, chunkGraph, moduleGraph, runtimeTemplate }
				) => {
					const { requestShortener } = runtimeTemplate;
					const source = new ConcatSource();
					const req = module.readableIdentifier(requestShortener);
					const reqStr = req.replace(/\*\//g, "*_/");
					const reqStrStar = "*".repeat(reqStr.length);
					source.add("/*!****" + reqStrStar + "****!*\\\n");
					source.add("  !*** " + reqStr + " ***!\n");
					source.add("  \\****" + reqStrStar + "****/\n");
					const exportsType = module.buildMeta.exportsType;
					source.add(
						Template.toComment(
							exportsType
								? `${exportsType} exports`
								: "unknown exports (runtime-defined)"
						) + "\n"
					);
					if (exportsType) {
						const exportsInfo = moduleGraph.getExportsInfo(module);
						printExportsInfoToSource(
							source,
							"",
							exportsInfo,
							moduleGraph,
							requestShortener
						);
					}
					source.add(
						Template.toComment(
							`runtime requirements: ${joinIterableWithComma(
								chunkGraph.getModuleRuntimeRequirements(module, chunk.runtime)
							)}`
						) + "\n"
					);
					const optimizationBailout = moduleGraph.getOptimizationBailout(
						module
					);
					if (optimizationBailout) {
						for (const text of optimizationBailout) {
							let code;
							if (typeof text === "function") {
								code = text(requestShortener);
							} else {
								code = text;
							}
							source.add(Template.toComment(`${code}`) + "\n");
						}
					}
					source.add(moduleSource);
					return source;
				}
			);
			hooks.chunkHash.tap("ModuleInfoHeaderPlugin", (chunk, hash) => {
				hash.update("ModuleInfoHeaderPlugin");
				hash.update("1");
			});
		});
	}
}
module.exports = ModuleInfoHeaderPlugin;