webpack/lib/BannerPlugin.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 Tobias Koppers @sokra
*/

"use strict";

const { ConcatSource } = require("webpack-sources");
const Compilation = require("./Compilation");
const ModuleFilenameHelpers = require("./ModuleFilenameHelpers");
const Template = require("./Template");
const createSchemaValidation = require("./util/create-schema-validation");

/** @typedef {import("../declarations/plugins/BannerPlugin").BannerFunction} BannerFunction */
/** @typedef {import("../declarations/plugins/BannerPlugin").BannerPluginArgument} BannerPluginArgument */
/** @typedef {import("../declarations/plugins/BannerPlugin").BannerPluginOptions} BannerPluginOptions */
/** @typedef {import("./Compilation").PathData} PathData */
/** @typedef {import("./Compiler")} Compiler */
/** @typedef {import("./TemplatedPathPlugin").TemplatePath} TemplatePath */

const validate = createSchemaValidation(
	/** @type {((value: typeof import("../schemas/plugins/BannerPlugin.json")) => boolean)} */
	(require("../schemas/plugins/BannerPlugin.check.js")),
	() => require("../schemas/plugins/BannerPlugin.json"),
	{
		name: "Banner Plugin",
		baseDataPath: "options"
	}
);

/**
 * @param {string} str string to wrap
 * @returns {string} wrapped string
 */
const wrapComment = str => {
	if (!str.includes("\n")) {
		return Template.toComment(str);
	}
	return `/*!\n * ${str
		.replace(/\*\//g, "* /")
		.split("\n")
		.join("\n * ")
		.replace(/\s+\n/g, "\n")
		.trimEnd()}\n */`;
};

const PLUGIN_NAME = "BannerPlugin";

class BannerPlugin {
	/**
	 * @param {BannerPluginArgument} options options object
	 */
	constructor(options) {
		if (typeof options === "string" || typeof options === "function") {
			options = {
				banner: options
			};
		}

		validate(options);

		this.options = options;

		const bannerOption = options.banner;
		if (typeof bannerOption === "function") {
			const getBanner = bannerOption;
			/** @type {BannerFunction} */
			this.banner = this.options.raw
				? getBanner
				: /** @type {BannerFunction} */ data => wrapComment(getBanner(data));
		} else {
			const banner = this.options.raw
				? bannerOption
				: wrapComment(bannerOption);
			/** @type {BannerFunction} */
			this.banner = () => banner;
		}
	}

	/**
	 * Apply the plugin
	 * @param {Compiler} compiler the compiler instance
	 * @returns {void}
	 */
	apply(compiler) {
		const options = this.options;
		const banner = this.banner;
		const matchObject = ModuleFilenameHelpers.matchObject.bind(
			undefined,
			options
		);
		const cache = new WeakMap();
		const stage =
			this.options.stage || Compilation.PROCESS_ASSETS_STAGE_ADDITIONS;

		compiler.hooks.compilation.tap(PLUGIN_NAME, compilation => {
			compilation.hooks.processAssets.tap({ name: PLUGIN_NAME, stage }, () => {
				for (const chunk of compilation.chunks) {
					if (options.entryOnly && !chunk.canBeInitial()) {
						continue;
					}

					for (const file of chunk.files) {
						if (!matchObject(file)) {
							continue;
						}

						/** @type {PathData} */
						const data = { chunk, filename: file };

						const comment = compilation.getPath(
							/** @type {TemplatePath} */
							(banner),
							data
						);

						compilation.updateAsset(file, old => {
							const cached = cache.get(old);
							if (!cached || cached.comment !== comment) {
								const source = options.footer
									? new ConcatSource(old, "\n", comment)
									: new ConcatSource(comment, "\n", old);
								cache.set(old, { source, comment });
								return source;
							}
							return cached.source;
						});
					}
				}
			});
		});
	}
}

module.exports = BannerPlugin;