webpack/lib/dependencies/RequireEnsureDependenciesBlockParserPlugin.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 RequireEnsureDependenciesBlock = require("./RequireEnsureDependenciesBlock");
const RequireEnsureDependency = require("./RequireEnsureDependency");
const RequireEnsureItemDependency = require("./RequireEnsureItemDependency");
const getFunctionExpression = require("./getFunctionExpression");

/** @typedef {import("../AsyncDependenciesBlock").GroupOptions} GroupOptions */
/** @typedef {import("../ChunkGroup").ChunkGroupOptions} ChunkGroupOptions */
/** @typedef {import("../Dependency").DependencyLocation} DependencyLocation */
/** @typedef {import("../javascript/BasicEvaluatedExpression")} BasicEvaluatedExpression */
/** @typedef {import("../javascript/JavascriptParser")} JavascriptParser */
/** @typedef {import("../javascript/JavascriptParser").Range} Range */

const PLUGIN_NAME = "RequireEnsureDependenciesBlockParserPlugin";

module.exports = class RequireEnsureDependenciesBlockParserPlugin {
	/**
	 * @param {JavascriptParser} parser the parser
	 * @returns {void}
	 */
	apply(parser) {
		parser.hooks.call.for("require.ensure").tap(PLUGIN_NAME, expr => {
			/** @type {string | GroupOptions | null} */
			let chunkName = null;
			let errorExpressionArg = null;
			let errorExpression = null;
			switch (expr.arguments.length) {
				case 4: {
					const chunkNameExpr = parser.evaluateExpression(expr.arguments[3]);
					if (!chunkNameExpr.isString()) return;
					chunkName =
						/** @type {string} */
						(chunkNameExpr.string);
				}
				// falls through
				case 3: {
					errorExpressionArg = expr.arguments[2];
					errorExpression = getFunctionExpression(errorExpressionArg);

					if (!errorExpression && !chunkName) {
						const chunkNameExpr = parser.evaluateExpression(expr.arguments[2]);
						if (!chunkNameExpr.isString()) return;
						chunkName =
							/** @type {string} */
							(chunkNameExpr.string);
					}
				}
				// falls through
				case 2: {
					const dependenciesExpr = parser.evaluateExpression(expr.arguments[0]);
					const dependenciesItems = /** @type {BasicEvaluatedExpression[]} */ (
						dependenciesExpr.isArray()
							? dependenciesExpr.items
							: [dependenciesExpr]
					);
					const successExpressionArg = expr.arguments[1];
					const successExpression = getFunctionExpression(successExpressionArg);

					if (successExpression) {
						parser.walkExpressions(successExpression.expressions);
					}
					if (errorExpression) {
						parser.walkExpressions(errorExpression.expressions);
					}

					const depBlock = new RequireEnsureDependenciesBlock(
						chunkName,
						/** @type {DependencyLocation} */
						(expr.loc)
					);
					const errorCallbackExists =
						expr.arguments.length === 4 ||
						(!chunkName && expr.arguments.length === 3);
					const dep = new RequireEnsureDependency(
						/** @type {Range} */ (expr.range),
						/** @type {Range} */ (expr.arguments[1].range),
						errorCallbackExists &&
							/** @type {Range} */ (expr.arguments[2].range)
					);
					dep.loc = /** @type {DependencyLocation} */ (expr.loc);
					depBlock.addDependency(dep);
					const old = parser.state.current;
					parser.state.current = /** @type {TODO} */ (depBlock);
					try {
						let failed = false;
						parser.inScope([], () => {
							for (const ee of dependenciesItems) {
								if (ee.isString()) {
									const ensureDependency = new RequireEnsureItemDependency(
										/** @type {string} */ (ee.string)
									);
									ensureDependency.loc =
										/** @type {DependencyLocation} */
										(expr.loc);
									depBlock.addDependency(ensureDependency);
								} else {
									failed = true;
								}
							}
						});
						if (failed) {
							return;
						}
						if (successExpression) {
							if (successExpression.fn.body.type === "BlockStatement") {
								// Opt-out of Dead Control Flow detection for this block
								const oldTerminated = parser.scope.terminated;
								parser.walkStatement(successExpression.fn.body);
								parser.scope.terminated = oldTerminated;
							} else {
								parser.walkExpression(successExpression.fn.body);
							}
						}
						old.addBlock(depBlock);
					} finally {
						parser.state.current = old;
					}
					if (!successExpression) {
						parser.walkExpression(successExpressionArg);
					}
					if (errorExpression) {
						if (errorExpression.fn.body.type === "BlockStatement") {
							parser.walkStatement(errorExpression.fn.body);
						} else {
							parser.walkExpression(errorExpression.fn.body);
						}
					} else if (errorExpressionArg) {
						parser.walkExpression(errorExpressionArg);
					}
					return true;
				}
			}
		});
	}
};