Parser Performance Collection

babel.config.js

@@ -14,12 +14,16 @@ module.exports = function(api) {
   let convertESM = true;
   let ignoreLib = true;
   let includeRuntime = false;
+  const nodeVersion = "6.9";
 
   switch (env) {
     // Configs used during bundling builds.
     case "babel-parser":
       convertESM = false;
       ignoreLib = false;
+      envOpts.targets = {
+        node: nodeVersion,
+      };
       break;
     case "standalone":
       convertESM = false;
@@ -29,7 +33,7 @@ module.exports = function(api) {
     case "production":
       // Config during builds before publish.
       envOpts.targets = {
-        node: "6.9",
+        node: nodeVersion,
       };
       break;
     case "development":

packages/babel-parser/package.json

@@ -30,7 +30,7 @@
   "devDependencies": {
     "@babel/helper-fixtures": "^7.2.0",
     "charcodes": "0.1.0",
-    "unicode-11.0.0": "^0.7.7"
+    "unicode-11.0.0": "^0.7.8"
   },
   "bin": {
     "parser": "./bin/babel-parser.js"

packages/babel-parser/scripts/generate-identifier-regex.js

@@ -60,11 +60,15 @@ function generate(chars) {
 const startData = generate(start);
 const contData = generate(cont);
 
+console.log("/* prettier-ignore */");
 console.log('let nonASCIIidentifierStartChars = "' + startData.nonASCII + '";');
+console.log("/* prettier-ignore */");
 console.log('let nonASCIIidentifierChars = "' + contData.nonASCII + '";');
+console.log("/* prettier-ignore */");
 console.log(
   "const astralIdentifierStartCodes = " + JSON.stringify(startData.astral) + ";"
 );
+console.log("/* prettier-ignore */");
 console.log(
   "const astralIdentifierCodes = " + JSON.stringify(contData.astral) + ";"
 );

packages/babel-parser/src/parser/base.js

@@ -1,7 +1,7 @@
 // @flow
 
 import type { Options } from "../options";
-import { reservedWords } from "../util/identifier";
+import { isES2015ReservedWord } from "../util/identifier";
 
 import type State from "../tokenizer/state";
 import type { PluginsMap } from "./index";
@@ -16,21 +16,21 @@ export default class BaseParser {
 
   // Initialized by Tokenizer
   state: State;
-  input: string;
 
   isReservedWord(word: string): boolean {
     if (word === "await") {
       return this.inModule;
     } else {
-      return reservedWords[6](word);
+      return isES2015ReservedWord(word);
     }
   }
 
   hasPlugin(name: string): boolean {
-    return Object.hasOwnProperty.call(this.plugins, name);
+    return this.plugins.has(name);
   }
 
   getPluginOption(plugin: string, name: string) {
-    if (this.hasPlugin(plugin)) return this.plugins[plugin][name];
+    // $FlowIssue
+    if (this.hasPlugin(plugin)) return this.plugins.get(plugin)[name];
   }
 }

packages/babel-parser/src/parser/expression.js

@@ -21,7 +21,11 @@
 import { types as tt, type TokenType } from "../tokenizer/types";
 import * as N from "../types";
 import LValParser from "./lval";
-import { reservedWords } from "../util/identifier";
+import {
+  isStrictReservedWord,
+  isStrictBindReservedWord,
+  isKeyword,
+} from "../util/identifier";
 import type { Pos, Position } from "../util/location";
 import * as charCodes from "charcodes";
 
@@ -525,7 +529,7 @@ export default class ExpressionParser extends LValParser {
     } else if (this.match(tt.questionDot)) {
       this.expectPlugin("optionalChaining");
       state.optionalChainMember = true;
-      if (noCalls && this.lookahead().type == tt.parenL) {
+      if (noCalls && this.lookahead().type === tt.parenL) {
         state.stop = true;
         return base;
       }
@@ -869,9 +873,9 @@ export default class ExpressionParser extends LValParser {
           return this.parseFunction(node, false, false, true);
         } else if (
           canBeArrow &&
-          !this.canInsertSemicolon() &&
           id.name === "async" &&
-          this.match(tt.name)
+          this.match(tt.name) &&
+          !this.canInsertSemicolon()
         ) {
           const oldYOAIPAP = this.state.yieldOrAwaitInPossibleArrowParameters;
           const oldInAsync = this.state.inAsync;
@@ -886,7 +890,8 @@ export default class ExpressionParser extends LValParser {
           return node;
         }
 
-        if (canBeArrow && !this.canInsertSemicolon() && this.eat(tt.arrow)) {
+        if (canBeArrow && this.match(tt.arrow) && !this.canInsertSemicolon()) {
+          this.next();
           const oldYOAIPAP = this.state.yieldOrAwaitInPossibleArrowParameters;
           this.state.yieldOrAwaitInPossibleArrowParameters = null;
           this.parseArrowExpression(node, [id]);
@@ -1146,7 +1151,11 @@ export default class ExpressionParser extends LValParser {
 
     const node = this.startNodeAt(startPos, startLoc);
     this.addExtra(node, "rawValue", value);
-    this.addExtra(node, "raw", this.input.slice(startPos, this.state.end));
+    this.addExtra(
+      node,
+      "raw",
+      this.state.input.slice(startPos, this.state.end),
+    );
     node.value = value;
     this.next();
     return this.finishNode(node, type);
@@ -1365,7 +1374,7 @@ export default class ExpressionParser extends LValParser {
       }
     }
     elem.value = {
-      raw: this.input
+      raw: this.state.input
         .slice(this.state.start, this.state.end)
         .replace(/\r\n?/g, "\n"),
       cooked: this.state.value,
@@ -1967,7 +1976,8 @@ export default class ExpressionParser extends LValParser {
       if (
         (name === "class" || name === "function") &&
         (this.state.lastTokEnd !== this.state.lastTokStart + 1 ||
-          this.input.charCodeAt(this.state.lastTokStart) !== charCodes.dot)
+          this.state.input.charCodeAt(this.state.lastTokStart) !==
+            charCodes.dot)
       ) {
         this.state.context.pop();
       }
@@ -1991,8 +2001,8 @@ export default class ExpressionParser extends LValParser {
   ): void {
     if (
       this.state.strict &&
-      (reservedWords.strict(word) ||
-        (isBinding && reservedWords.strictBind(word)))
+      (isStrictReservedWord(word) ||
+        (isBinding && isStrictBindReservedWord(word)))
     ) {
       this.raise(startLoc, word + " is a reserved word in strict mode");
     }
@@ -2011,7 +2021,7 @@ export default class ExpressionParser extends LValParser {
       );
     }
 
-    if (this.isReservedWord(word) || (checkKeywords && this.isKeyword(word))) {
+    if (this.isReservedWord(word) || (checkKeywords && isKeyword(word))) {
       this.raise(startLoc, word + " is a reserved word");
     }
   }
@@ -2071,8 +2081,8 @@ export default class ExpressionParser extends LValParser {
     this.next();
     if (
       this.match(tt.semi) ||
-      this.canInsertSemicolon() ||
-      (!this.match(tt.star) && !this.state.type.startsExpr)
+      (!this.match(tt.star) && !this.state.type.startsExpr) ||
+      this.canInsertSemicolon()
     ) {
       node.delegate = false;
       node.argument = null;

packages/babel-parser/src/parser/index.js

@@ -6,9 +6,7 @@ import type { PluginList } from "../plugin-utils";
 import { getOptions } from "../options";
 import StatementParser from "./statement";
 
-export type PluginsMap = {
-  [key: string]: { [option: string]: any },
-};
+export type PluginsMap = Map<string, { [string]: any }>;
 
 export default class Parser extends StatementParser {
   // Forward-declaration so typescript plugin can override jsx plugin
@@ -22,7 +20,6 @@ export default class Parser extends StatementParser {
 
     this.options = options;
     this.inModule = this.options.sourceType === "module";
-    this.input = input;
     this.plugins = pluginsMap(this.options.plugins);
     this.filename = options.sourceFilename;
   }
@@ -36,10 +33,10 @@ export default class Parser extends StatementParser {
 }
 
 function pluginsMap(plugins: PluginList): PluginsMap {
-  const pluginMap: PluginsMap = (Object.create(null): Object);
+  const pluginMap: PluginsMap = new Map();
   for (const plugin of plugins) {
-    const [name, options = {}] = Array.isArray(plugin) ? plugin : [plugin, {}];
-    if (!pluginMap[name]) pluginMap[name] = options || {};
+    const [name, options] = Array.isArray(plugin) ? plugin : [plugin, {}];
+    if (!pluginMap.has(name)) pluginMap.set(name, options || {});
   }
   return pluginMap;
 }

packages/babel-parser/src/parser/location.js

@@ -21,7 +21,7 @@ export default class LocationParser extends CommentsParser {
       code?: string,
     } = {},
   ): empty {
-    const loc = getLineInfo(this.input, pos);
+    const loc = getLineInfo(this.state.input, pos);
     message += ` (${loc.line}:${loc.column})`;
     // $FlowIgnore
     const err: SyntaxError & { pos: number, loc: Position } = new SyntaxError(

packages/babel-parser/src/parser/lval.js

@@ -56,9 +56,13 @@ export default class LValParser extends NodeUtils {
 
         case "ObjectExpression":
           node.type = "ObjectPattern";
-          for (let index = 0; index < node.properties.length; index++) {
-            const prop = node.properties[index];
-            const isLast = index === node.properties.length - 1;
+          for (
+            let i = 0, length = node.properties.length, last = length - 1;
+            i < length;
+            i++
+          ) {
+            const prop = node.properties[i];
+            const isLast = i === last;
             this.toAssignableObjectExpressionProp(prop, isBinding, isLast);
           }
           break;
@@ -145,12 +149,10 @@ export default class LValParser extends NodeUtils {
         const arg = last.argument;
         this.toAssignable(arg, isBinding, contextDescription);
         if (
-          [
-            "Identifier",
-            "MemberExpression",
-            "ArrayPattern",
-            "ObjectPattern",
-          ].indexOf(arg.type) === -1
+          arg.type !== "Identifier" &&
+          arg.type !== "MemberExpression" &&
+          arg.type !== "ArrayPattern" &&
+          arg.type !== "ObjectPattern"
         ) {
           this.unexpected(arg.start);
         }
@@ -426,13 +428,12 @@ export default class LValParser extends NodeUtils {
   }
 
   checkToRestConversion(node: SpreadElement): void {
-    const validArgumentTypes = ["Identifier", "MemberExpression"];
-
-    if (validArgumentTypes.indexOf(node.argument.type) !== -1) {
-      return;
+    if (
+      node.argument.type !== "Identifier" &&
+      node.argument.type !== "MemberExpression"
+    ) {
+      this.raise(node.argument.start, "Invalid rest operator's argument");
     }
-
-    this.raise(node.argument.start, "Invalid rest operator's argument");
   }
 
   checkCommaAfterRest(close: TokenType, kind: string): void {

packages/babel-parser/src/parser/node.js

@@ -7,8 +7,6 @@ import type { Comment, Node as NodeType, NodeBase } from "../types";
 
 // Start an AST node, attaching a start offset.
 
-const commentKeys = ["leadingComments", "trailingComments", "innerComments"];
-
 class Node implements NodeBase {
   constructor(parser: Parser, pos: number, loc: Position) {
     this.type = "";
@@ -31,16 +29,22 @@ class Node implements NodeBase {
 
   __clone(): this {
     // $FlowIgnore
-    const node2: any = new Node();
-    Object.keys(this).forEach(key => {
+    const newNode: any = new Node();
+    const keys = Object.keys(this);
+    for (let i = 0, length = keys.length; i < length; i++) {
+      const key = keys[i];
       // Do not clone comments that are already attached to the node
-      if (commentKeys.indexOf(key) < 0) {
+      if (
+        key !== "leadingComments" &&
+        key !== "trailingComments" &&
+        key !== "innerComments"
+      ) {
         // $FlowIgnore
-        node2[key] = this[key];
+        newNode[key] = this[key];
       }
-    });
+    }
 
-    return node2;
+    return newNode;
   }
 }