| /** | |
|  * @fileoverview Rule to flag the use of empty character classes in regular expressions | |
|  * @author Ian Christian Myers | |
|  */ | |
| 
 | |
| "use strict"; | |
| 
 | |
| //------------------------------------------------------------------------------ | |
| // Requirements | |
| //------------------------------------------------------------------------------ | |
|  | |
| const { RegExpParser, visitRegExpAST } = require("@eslint-community/regexpp"); | |
| 
 | |
| //------------------------------------------------------------------------------ | |
| // Helpers | |
| //------------------------------------------------------------------------------ | |
|  | |
| const parser = new RegExpParser(); | |
| const QUICK_TEST_REGEX = /\[\]/u; | |
| 
 | |
| //------------------------------------------------------------------------------ | |
| // Rule Definition | |
| //------------------------------------------------------------------------------ | |
|  | |
| /** @type {import('../shared/types').Rule} */ | |
| module.exports = { | |
|     meta: { | |
|         type: "problem", | |
| 
 | |
|         docs: { | |
|             description: "Disallow empty character classes in regular expressions", | |
|             recommended: true, | |
|             url: "https://eslint.org/docs/latest/rules/no-empty-character-class" | |
|         }, | |
| 
 | |
|         schema: [], | |
| 
 | |
|         messages: { | |
|             unexpected: "Empty class." | |
|         } | |
|     }, | |
| 
 | |
|     create(context) { | |
|         return { | |
|             "Literal[regex]"(node) { | |
|                 const { pattern, flags } = node.regex; | |
| 
 | |
|                 if (!QUICK_TEST_REGEX.test(pattern)) { | |
|                     return; | |
|                 } | |
| 
 | |
|                 let regExpAST; | |
| 
 | |
|                 try { | |
|                     regExpAST = parser.parsePattern(pattern, 0, pattern.length, { | |
|                         unicode: flags.includes("u"), | |
|                         unicodeSets: flags.includes("v") | |
|                     }); | |
|                 } catch { | |
| 
 | |
|                     // Ignore regular expressions that regexpp cannot parse | |
|                     return; | |
|                 } | |
| 
 | |
|                 visitRegExpAST(regExpAST, { | |
|                     onCharacterClassEnter(characterClass) { | |
|                         if (!characterClass.negate && characterClass.elements.length === 0) { | |
|                             context.report({ node, messageId: "unexpected" }); | |
|                         } | |
|                     } | |
|                 }); | |
|             } | |
|         }; | |
| 
 | |
|     } | |
| };
 |