| /** | |
|  * @fileoverview Rule to disallow a duplicate case label. | |
|  * @author Dieter Oberkofler | |
|  * @author Burak Yigit Kaya | |
|  */ | |
| 
 | |
| "use strict"; | |
| 
 | |
| //------------------------------------------------------------------------------ | |
| // Requirements | |
| //------------------------------------------------------------------------------ | |
|  | |
| const astUtils = require("./utils/ast-utils"); | |
| 
 | |
| //------------------------------------------------------------------------------ | |
| // Rule Definition | |
| //------------------------------------------------------------------------------ | |
|  | |
| /** @type {import('../shared/types').Rule} */ | |
| module.exports = { | |
|     meta: { | |
|         type: "problem", | |
| 
 | |
|         docs: { | |
|             description: "Disallow duplicate case labels", | |
|             recommended: true, | |
|             url: "https://eslint.org/docs/latest/rules/no-duplicate-case" | |
|         }, | |
| 
 | |
|         schema: [], | |
| 
 | |
|         messages: { | |
|             unexpected: "Duplicate case label." | |
|         } | |
|     }, | |
| 
 | |
|     create(context) { | |
|         const sourceCode = context.sourceCode; | |
| 
 | |
|         /** | |
|          * Determines whether the two given nodes are considered to be equal. | |
|          * @param {ASTNode} a First node. | |
|          * @param {ASTNode} b Second node. | |
|          * @returns {boolean} `true` if the nodes are considered to be equal. | |
|          */ | |
|         function equal(a, b) { | |
|             if (a.type !== b.type) { | |
|                 return false; | |
|             } | |
| 
 | |
|             return astUtils.equalTokens(a, b, sourceCode); | |
|         } | |
|         return { | |
|             SwitchStatement(node) { | |
|                 const previousTests = []; | |
| 
 | |
|                 for (const switchCase of node.cases) { | |
|                     if (switchCase.test) { | |
|                         const test = switchCase.test; | |
| 
 | |
|                         if (previousTests.some(previousTest => equal(previousTest, test))) { | |
|                             context.report({ node: switchCase, messageId: "unexpected" }); | |
|                         } else { | |
|                             previousTests.push(test); | |
|                         } | |
|                     } | |
|                 } | |
|             } | |
|         }; | |
|     } | |
| };
 |