CommonJsExportsParserPlugin.js 14 KB

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  1. /*
  2. MIT License http://www.opensource.org/licenses/mit-license.php
  3. Author Tobias Koppers @sokra
  4. */
  5. "use strict";
  6. const RuntimeGlobals = require("../RuntimeGlobals");
  7. const formatLocation = require("../formatLocation");
  8. const { evaluateToString } = require("../javascript/JavascriptParserHelpers");
  9. const propertyAccess = require("../util/propertyAccess");
  10. const CommonJsExportRequireDependency = require("./CommonJsExportRequireDependency");
  11. const CommonJsExportsDependency = require("./CommonJsExportsDependency");
  12. const CommonJsSelfReferenceDependency = require("./CommonJsSelfReferenceDependency");
  13. const DynamicExports = require("./DynamicExports");
  14. const HarmonyExports = require("./HarmonyExports");
  15. const ModuleDecoratorDependency = require("./ModuleDecoratorDependency");
  16. /** @typedef {import("estree").AssignmentExpression} AssignmentExpression */
  17. /** @typedef {import("estree").CallExpression} CallExpression */
  18. /** @typedef {import("estree").Expression} Expression */
  19. /** @typedef {import("estree").Super} Super */
  20. /** @typedef {import("../Dependency").DependencyLocation} DependencyLocation */
  21. /** @typedef {import("../ModuleGraph")} ModuleGraph */
  22. /** @typedef {import("../NormalModule")} NormalModule */
  23. /** @typedef {import("../javascript/BasicEvaluatedExpression")} BasicEvaluatedExpression */
  24. /** @typedef {import("../javascript/JavascriptParser")} JavascriptParser */
  25. /** @typedef {import("../javascript/JavascriptParser").Range} Range */
  26. /** @typedef {import("../javascript/JavascriptParser").StatementPath} StatementPath */
  27. /** @typedef {import("./CommonJsDependencyHelpers").CommonJSDependencyBaseKeywords} CommonJSDependencyBaseKeywords */
  28. /**
  29. * This function takes a generic expression and detects whether it is an ObjectExpression.
  30. * This is used in the context of parsing CommonJS exports to get the value of the property descriptor
  31. * when the `exports` object is assigned to `Object.defineProperty`.
  32. *
  33. * In CommonJS modules, the `exports` object can be assigned to `Object.defineProperty` and therefore
  34. * webpack has to detect this case and get the value key of the property descriptor. See the following example
  35. * for more information: https://astexplorer.net/#/gist/83ce51a4e96e59d777df315a6d111da6/8058ead48a1bb53c097738225db0967ef7f70e57
  36. *
  37. * This would be an example of a CommonJS module that exports an object with a property descriptor:
  38. * ```js
  39. * Object.defineProperty(exports, "__esModule", { value: true });
  40. * exports.foo = void 0;
  41. * exports.foo = "bar";
  42. * ```
  43. * @param {Expression} expr expression
  44. * @returns {Expression | undefined} returns the value of property descriptor
  45. */
  46. const getValueOfPropertyDescription = expr => {
  47. if (expr.type !== "ObjectExpression") return;
  48. for (const property of expr.properties) {
  49. if (property.type === "SpreadElement" || property.computed) continue;
  50. const key = property.key;
  51. if (key.type !== "Identifier" || key.name !== "value") continue;
  52. return /** @type {Expression} */ (property.value);
  53. }
  54. };
  55. /**
  56. * The purpose of this function is to check whether an expression is a truthy literal or not. This is
  57. * useful when parsing CommonJS exports, because CommonJS modules can export any value, including falsy
  58. * values like `null` and `false`. However, exports should only be created if the exported value is truthy.
  59. * @param {Expression} expr expression being checked
  60. * @returns {boolean} true, when the expression is a truthy literal
  61. */
  62. const isTruthyLiteral = expr => {
  63. switch (expr.type) {
  64. case "Literal":
  65. return Boolean(expr.value);
  66. case "UnaryExpression":
  67. if (expr.operator === "!") return isFalsyLiteral(expr.argument);
  68. }
  69. return false;
  70. };
  71. /**
  72. * The purpose of this function is to check whether an expression is a falsy literal or not. This is
  73. * useful when parsing CommonJS exports, because CommonJS modules can export any value, including falsy
  74. * values like `null` and `false`. However, exports should only be created if the exported value is truthy.
  75. * @param {Expression} expr expression being checked
  76. * @returns {boolean} true, when the expression is a falsy literal
  77. */
  78. const isFalsyLiteral = expr => {
  79. switch (expr.type) {
  80. case "Literal":
  81. return !expr.value;
  82. case "UnaryExpression":
  83. if (expr.operator === "!") return isTruthyLiteral(expr.argument);
  84. }
  85. return false;
  86. };
  87. /**
  88. * @param {JavascriptParser} parser the parser
  89. * @param {Expression} expr expression
  90. * @returns {{ argument: BasicEvaluatedExpression, ids: string[] } | undefined} parsed call
  91. */
  92. const parseRequireCall = (parser, expr) => {
  93. const ids = [];
  94. while (expr.type === "MemberExpression") {
  95. if (expr.object.type === "Super") return;
  96. if (!expr.property) return;
  97. const prop = expr.property;
  98. if (expr.computed) {
  99. if (prop.type !== "Literal") return;
  100. ids.push(`${prop.value}`);
  101. } else {
  102. if (prop.type !== "Identifier") return;
  103. ids.push(prop.name);
  104. }
  105. expr = expr.object;
  106. }
  107. if (expr.type !== "CallExpression" || expr.arguments.length !== 1) return;
  108. const callee = expr.callee;
  109. if (
  110. callee.type !== "Identifier" ||
  111. parser.getVariableInfo(callee.name) !== "require"
  112. ) {
  113. return;
  114. }
  115. const arg = expr.arguments[0];
  116. if (arg.type === "SpreadElement") return;
  117. const argValue = parser.evaluateExpression(arg);
  118. return { argument: argValue, ids: ids.reverse() };
  119. };
  120. const PLUGIN_NAME = "CommonJsExportsParserPlugin";
  121. class CommonJsExportsParserPlugin {
  122. /**
  123. * @param {ModuleGraph} moduleGraph module graph
  124. */
  125. constructor(moduleGraph) {
  126. this.moduleGraph = moduleGraph;
  127. }
  128. /**
  129. * @param {JavascriptParser} parser the parser
  130. * @returns {void}
  131. */
  132. apply(parser) {
  133. const enableStructuredExports = () => {
  134. DynamicExports.enable(parser.state);
  135. };
  136. /**
  137. * @param {boolean} topLevel true, when the export is on top level
  138. * @param {string[]} members members of the export
  139. * @param {Expression | undefined} valueExpr expression for the value
  140. * @returns {void}
  141. */
  142. const checkNamespace = (topLevel, members, valueExpr) => {
  143. if (!DynamicExports.isEnabled(parser.state)) return;
  144. if (members.length > 0 && members[0] === "__esModule") {
  145. if (valueExpr && isTruthyLiteral(valueExpr) && topLevel) {
  146. DynamicExports.setFlagged(parser.state);
  147. } else {
  148. DynamicExports.setDynamic(parser.state);
  149. }
  150. }
  151. };
  152. /**
  153. * @param {string=} reason reason
  154. */
  155. const bailout = reason => {
  156. DynamicExports.bailout(parser.state);
  157. if (reason) bailoutHint(reason);
  158. };
  159. /**
  160. * @param {string} reason reason
  161. */
  162. const bailoutHint = reason => {
  163. this.moduleGraph
  164. .getOptimizationBailout(parser.state.module)
  165. .push(`CommonJS bailout: ${reason}`);
  166. };
  167. // metadata //
  168. parser.hooks.evaluateTypeof
  169. .for("module")
  170. .tap(PLUGIN_NAME, evaluateToString("object"));
  171. parser.hooks.evaluateTypeof
  172. .for("exports")
  173. .tap(PLUGIN_NAME, evaluateToString("object"));
  174. // exporting //
  175. /**
  176. * @param {AssignmentExpression} expr expression
  177. * @param {CommonJSDependencyBaseKeywords} base commonjs base keywords
  178. * @param {string[]} members members of the export
  179. * @returns {boolean | undefined} true, when the expression was handled
  180. */
  181. const handleAssignExport = (expr, base, members) => {
  182. if (HarmonyExports.isEnabled(parser.state)) return;
  183. // Handle reexporting
  184. const requireCall = parseRequireCall(parser, expr.right);
  185. if (
  186. requireCall &&
  187. requireCall.argument.isString() &&
  188. (members.length === 0 || members[0] !== "__esModule")
  189. ) {
  190. enableStructuredExports();
  191. // It's possible to reexport __esModule, so we must convert to a dynamic module
  192. if (members.length === 0) DynamicExports.setDynamic(parser.state);
  193. const dep = new CommonJsExportRequireDependency(
  194. /** @type {Range} */ (expr.range),
  195. null,
  196. base,
  197. members,
  198. /** @type {string} */ (requireCall.argument.string),
  199. requireCall.ids,
  200. !parser.isStatementLevelExpression(expr)
  201. );
  202. dep.loc = /** @type {DependencyLocation} */ (expr.loc);
  203. dep.optional = Boolean(parser.scope.inTry);
  204. parser.state.module.addDependency(dep);
  205. return true;
  206. }
  207. if (members.length === 0) return;
  208. enableStructuredExports();
  209. const remainingMembers = members;
  210. checkNamespace(
  211. /** @type {StatementPath} */
  212. (parser.statementPath).length === 1 &&
  213. parser.isStatementLevelExpression(expr),
  214. remainingMembers,
  215. expr.right
  216. );
  217. const dep = new CommonJsExportsDependency(
  218. /** @type {Range} */ (expr.left.range),
  219. null,
  220. base,
  221. remainingMembers
  222. );
  223. dep.loc = /** @type {DependencyLocation} */ (expr.loc);
  224. parser.state.module.addDependency(dep);
  225. parser.walkExpression(expr.right);
  226. return true;
  227. };
  228. parser.hooks.assignMemberChain
  229. .for("exports")
  230. .tap(PLUGIN_NAME, (expr, members) =>
  231. handleAssignExport(expr, "exports", members)
  232. );
  233. parser.hooks.assignMemberChain
  234. .for("this")
  235. .tap(PLUGIN_NAME, (expr, members) => {
  236. if (!parser.scope.topLevelScope) return;
  237. return handleAssignExport(expr, "this", members);
  238. });
  239. parser.hooks.assignMemberChain
  240. .for("module")
  241. .tap(PLUGIN_NAME, (expr, members) => {
  242. if (members[0] !== "exports") return;
  243. return handleAssignExport(expr, "module.exports", members.slice(1));
  244. });
  245. parser.hooks.call
  246. .for("Object.defineProperty")
  247. .tap(PLUGIN_NAME, expression => {
  248. const expr = /** @type {CallExpression} */ (expression);
  249. if (!parser.isStatementLevelExpression(expr)) return;
  250. if (expr.arguments.length !== 3) return;
  251. if (expr.arguments[0].type === "SpreadElement") return;
  252. if (expr.arguments[1].type === "SpreadElement") return;
  253. if (expr.arguments[2].type === "SpreadElement") return;
  254. const exportsArg = parser.evaluateExpression(expr.arguments[0]);
  255. if (!exportsArg.isIdentifier()) return;
  256. if (
  257. exportsArg.identifier !== "exports" &&
  258. exportsArg.identifier !== "module.exports" &&
  259. (exportsArg.identifier !== "this" || !parser.scope.topLevelScope)
  260. ) {
  261. return;
  262. }
  263. const propertyArg = parser.evaluateExpression(expr.arguments[1]);
  264. const property = propertyArg.asString();
  265. if (typeof property !== "string") return;
  266. enableStructuredExports();
  267. const descArg = expr.arguments[2];
  268. checkNamespace(
  269. /** @type {StatementPath} */
  270. (parser.statementPath).length === 1,
  271. [property],
  272. getValueOfPropertyDescription(descArg)
  273. );
  274. const dep = new CommonJsExportsDependency(
  275. /** @type {Range} */ (expr.range),
  276. /** @type {Range} */ (expr.arguments[2].range),
  277. `Object.defineProperty(${exportsArg.identifier})`,
  278. [property]
  279. );
  280. dep.loc = /** @type {DependencyLocation} */ (expr.loc);
  281. parser.state.module.addDependency(dep);
  282. parser.walkExpression(expr.arguments[2]);
  283. return true;
  284. });
  285. // Self reference //
  286. /**
  287. * @param {Expression | Super} expr expression
  288. * @param {CommonJSDependencyBaseKeywords} base commonjs base keywords
  289. * @param {string[]} members members of the export
  290. * @param {CallExpression=} call call expression
  291. * @returns {boolean | void} true, when the expression was handled
  292. */
  293. const handleAccessExport = (expr, base, members, call) => {
  294. if (HarmonyExports.isEnabled(parser.state)) return;
  295. if (members.length === 0) {
  296. bailout(
  297. `${base} is used directly at ${formatLocation(
  298. /** @type {DependencyLocation} */ (expr.loc)
  299. )}`
  300. );
  301. }
  302. if (call && members.length === 1) {
  303. bailoutHint(
  304. `${base}${propertyAccess(
  305. members
  306. )}(...) prevents optimization as ${base} is passed as call context at ${formatLocation(
  307. /** @type {DependencyLocation} */ (expr.loc)
  308. )}`
  309. );
  310. }
  311. const dep = new CommonJsSelfReferenceDependency(
  312. /** @type {Range} */ (expr.range),
  313. base,
  314. members,
  315. Boolean(call)
  316. );
  317. dep.loc = /** @type {DependencyLocation} */ (expr.loc);
  318. parser.state.module.addDependency(dep);
  319. if (call) {
  320. parser.walkExpressions(call.arguments);
  321. }
  322. return true;
  323. };
  324. parser.hooks.callMemberChain
  325. .for("exports")
  326. .tap(PLUGIN_NAME, (expr, members) =>
  327. handleAccessExport(expr.callee, "exports", members, expr)
  328. );
  329. parser.hooks.expressionMemberChain
  330. .for("exports")
  331. .tap(PLUGIN_NAME, (expr, members) =>
  332. handleAccessExport(expr, "exports", members)
  333. );
  334. parser.hooks.expression
  335. .for("exports")
  336. .tap(PLUGIN_NAME, expr => handleAccessExport(expr, "exports", []));
  337. parser.hooks.callMemberChain
  338. .for("module")
  339. .tap(PLUGIN_NAME, (expr, members) => {
  340. if (members[0] !== "exports") return;
  341. return handleAccessExport(
  342. expr.callee,
  343. "module.exports",
  344. members.slice(1),
  345. expr
  346. );
  347. });
  348. parser.hooks.expressionMemberChain
  349. .for("module")
  350. .tap(PLUGIN_NAME, (expr, members) => {
  351. if (members[0] !== "exports") return;
  352. return handleAccessExport(expr, "module.exports", members.slice(1));
  353. });
  354. parser.hooks.expression
  355. .for("module.exports")
  356. .tap(PLUGIN_NAME, expr => handleAccessExport(expr, "module.exports", []));
  357. parser.hooks.callMemberChain
  358. .for("this")
  359. .tap(PLUGIN_NAME, (expr, members) => {
  360. if (!parser.scope.topLevelScope) return;
  361. return handleAccessExport(expr.callee, "this", members, expr);
  362. });
  363. parser.hooks.expressionMemberChain
  364. .for("this")
  365. .tap(PLUGIN_NAME, (expr, members) => {
  366. if (!parser.scope.topLevelScope) return;
  367. return handleAccessExport(expr, "this", members);
  368. });
  369. parser.hooks.expression.for("this").tap(PLUGIN_NAME, expr => {
  370. if (!parser.scope.topLevelScope) return;
  371. return handleAccessExport(expr, "this", []);
  372. });
  373. // Bailouts //
  374. parser.hooks.expression.for("module").tap(PLUGIN_NAME, expr => {
  375. bailout();
  376. const isHarmony = HarmonyExports.isEnabled(parser.state);
  377. const dep = new ModuleDecoratorDependency(
  378. isHarmony
  379. ? RuntimeGlobals.harmonyModuleDecorator
  380. : RuntimeGlobals.nodeModuleDecorator,
  381. !isHarmony
  382. );
  383. dep.loc = /** @type {DependencyLocation} */ (expr.loc);
  384. parser.state.module.addDependency(dep);
  385. return true;
  386. });
  387. }
  388. }
  389. module.exports = CommonJsExportsParserPlugin;