| 1 | /** |
| 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. |
| 3 | * |
| 4 | * This source code is licensed under the MIT license found in the |
| 5 | * LICENSE file in the root directory of this source tree. |
| 6 | */ |
| 7 | |
| 8 | /** |
| 9 | * https://tc39.es/ecma262/multipage/ecmascript-language-lexical-grammar.html#sec-keywords-and-reserved-words |
| 10 | */ |
| 11 | |
| 12 | /** |
| 13 | * Note: `await` and `yield` are contextually allowed as identifiers. |
| 14 | * await: reserved inside async functions and modules |
| 15 | * yield: reserved inside generator functions |
| 16 | * |
| 17 | * Note: `async` is not reserved. |
| 18 | */ |
| 19 | const RESERVED_WORDS = new Set([ |
| 20 | 'break', |
| 21 | 'case', |
| 22 | 'catch', |
| 23 | 'class', |
| 24 | 'const', |
| 25 | 'continue', |
| 26 | 'debugger', |
| 27 | 'default', |
| 28 | 'delete', |
| 29 | 'do', |
| 30 | 'else', |
| 31 | 'enum', |
| 32 | 'export', |
| 33 | 'extends', |
| 34 | 'false', |
| 35 | 'finally', |
| 36 | 'for', |
| 37 | 'function', |
| 38 | 'if', |
| 39 | 'import', |
| 40 | 'in', |
| 41 | 'instanceof', |
| 42 | 'new', |
| 43 | 'null', |
| 44 | 'return', |
| 45 | 'super', |
| 46 | 'switch', |
| 47 | 'this', |
| 48 | 'throw', |
| 49 | 'true', |
| 50 | 'try', |
| 51 | 'typeof', |
| 52 | 'var', |
| 53 | 'void', |
| 54 | 'while', |
| 55 | 'with', |
| 56 | ]); |
| 57 | |
| 58 | /** |
| 59 | * Reserved when a module has a 'use strict' directive. |
| 60 | */ |
| 61 | const STRICT_MODE_RESERVED_WORDS = new Set([ |
| 62 | 'let', |
| 63 | 'static', |
| 64 | 'implements', |
| 65 | 'interface', |
| 66 | 'package', |
| 67 | 'private', |
| 68 | 'protected', |
| 69 | 'public', |
| 70 | ]); |
| 71 | /** |
| 72 | * The names arguments and eval are not keywords, but they are subject to some restrictions in |
| 73 | * strict mode code. |
| 74 | */ |
| 75 | const STRICT_MODE_RESTRICTED_WORDS = new Set(['eval', 'arguments']); |
| 76 | |
| 77 | /** |
| 78 | * Conservative check for whether an identifer name is reserved or not. We assume that code is |
| 79 | * written with strict mode. |
| 80 | */ |
| 81 | export function isReservedWord(identifierName: string): boolean { |
| 82 | return ( |
| 83 | RESERVED_WORDS.has(identifierName) || |
| 84 | STRICT_MODE_RESERVED_WORDS.has(identifierName) || |
| 85 | STRICT_MODE_RESTRICTED_WORDS.has(identifierName) |
| 86 | ); |
| 87 | } |