webpack/lib/CompatibilityPlugin.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 ConstDependency = require("./dependencies/ConstDependency");

/** @typedef {import("./Compiler")} Compiler */
/** @typedef {import("./javascript/JavascriptParser")} JavascriptParser */

const nestedWebpackRequireTag = Symbol("nested __webpack_require__");

class CompatibilityPlugin {
	/**
	 * Apply the plugin
	 * @param {Compiler} compiler the compiler instance
	 * @returns {void}
	 */
	apply(compiler) {
		compiler.hooks.compilation.tap(
			"CompatibilityPlugin",
			(compilation, { normalModuleFactory }) => {
				compilation.dependencyTemplates.set(
					ConstDependency,
					new ConstDependency.Template()
				);

				normalModuleFactory.hooks.parser
					.for("javascript/auto")
					.tap("CompatibilityPlugin", (parser, parserOptions) => {
						if (
							parserOptions.browserify !== undefined &&
							!parserOptions.browserify
						)
							return;

						parser.hooks.call
							.for("require")
							.tap("CompatibilityPlugin", expr => {
								// support for browserify style require delegator: "require(o, !0)"
								if (expr.arguments.length !== 2) return;
								const second = parser.evaluateExpression(expr.arguments[1]);
								if (!second.isBoolean()) return;
								if (second.asBool() !== true) return;
								const dep = new ConstDependency("require", expr.callee.range);
								dep.loc = expr.loc;
								if (parser.state.current.dependencies.length > 0) {
									const last =
										parser.state.current.dependencies[
											parser.state.current.dependencies.length - 1
										];
									if (
										last.critical &&
										last.options &&
										last.options.request === "." &&
										last.userRequest === "." &&
										last.options.recursive
									)
										parser.state.current.dependencies.pop();
								}
								parser.state.module.addPresentationalDependency(dep);
								return true;
							});
					});

				/**
				 * @param {JavascriptParser} parser the parser
				 * @returns {void}
				 */
				const handler = parser => {
					// Handle nested requires
					parser.hooks.preStatement.tap("CompatibilityPlugin", statement => {
						if (
							statement.type === "FunctionDeclaration" &&
							statement.id &&
							statement.id.name === "__webpack_require__"
						) {
							const newName = `__nested_webpack_require_${statement.range[0]}__`;
							parser.tagVariable(statement.id.name, nestedWebpackRequireTag, {
								name: newName,
								declaration: {
									updated: false,
									loc: statement.id.loc,
									range: statement.id.range
								}
							});
							return true;
						}
					});
					parser.hooks.pattern
						.for("__webpack_require__")
						.tap("CompatibilityPlugin", pattern => {
							const newName = `__nested_webpack_require_${pattern.range[0]}__`;
							parser.tagVariable(pattern.name, nestedWebpackRequireTag, {
								name: newName,
								declaration: {
									updated: false,
									loc: pattern.loc,
									range: pattern.range
								}
							});
							return true;
						});
					parser.hooks.expression
						.for(nestedWebpackRequireTag)
						.tap("CompatibilityPlugin", expr => {
							const { name, declaration } = parser.currentTagData;
							if (!declaration.updated) {
								const dep = new ConstDependency(name, declaration.range);
								dep.loc = declaration.loc;
								parser.state.module.addPresentationalDependency(dep);
								declaration.updated = true;
							}
							const dep = new ConstDependency(name, expr.range);
							dep.loc = expr.loc;
							parser.state.module.addPresentationalDependency(dep);
							return true;
						});

					// Handle hashbang
					parser.hooks.program.tap(
						"CompatibilityPlugin",
						(program, comments) => {
							if (comments.length === 0) return;
							const c = comments[0];
							if (c.type === "Line" && c.range[0] === 0) {
								if (parser.state.source.slice(0, 2).toString() !== "#!") return;
								// this is a hashbang comment
								const dep = new ConstDependency("//", 0);
								dep.loc = c.loc;
								parser.state.module.addPresentationalDependency(dep);
							}
						}
					);
				};

				normalModuleFactory.hooks.parser
					.for("javascript/auto")
					.tap("CompatibilityPlugin", handler);
				normalModuleFactory.hooks.parser
					.for("javascript/dynamic")
					.tap("CompatibilityPlugin", handler);
				normalModuleFactory.hooks.parser
					.for("javascript/esm")
					.tap("CompatibilityPlugin", handler);
			}
		);
	}
}
module.exports = CompatibilityPlugin;