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| /** | |
| * @fileoverview Restrict usage of duplicate imports. | |
| * @author Simen Bekkhus | |
| */ | |
| "use strict"; | |
| //------------------------------------------------------------------------------ | |
| // Rule Definition | |
| //------------------------------------------------------------------------------ | |
| /** | |
| * Returns the name of the module imported or re-exported. | |
| * @param {ASTNode} node A node to get. | |
| * @returns {string} the name of the module, or empty string if no name. | |
| */ | |
| function getValue(node) { | |
| if (node && node.source && node.source.value) { | |
| return node.source.value.trim(); | |
| } | |
| return ""; | |
| } | |
| /** | |
| * Checks if the name of the import or export exists in the given array, and reports if so. | |
| * @param {RuleContext} context The ESLint rule context object. | |
| * @param {ASTNode} node A node to get. | |
| * @param {string} value The name of the imported or exported module. | |
| * @param {string[]} array The array containing other imports or exports in the file. | |
| * @param {string} messageId A messageId to be reported after the name of the module | |
| * | |
| * @returns {void} No return value | |
| */ | |
| function checkAndReport(context, node, value, array, messageId) { | |
| if (array.indexOf(value) !== -1) { | |
| context.report({ | |
| node, | |
| messageId, | |
| data: { | |
| module: value | |
| } | |
| }); | |
| } | |
| } | |
| /** | |
| * @callback nodeCallback | |
| * @param {ASTNode} node A node to handle. | |
| */ | |
| /** | |
| * Returns a function handling the imports of a given file | |
| * @param {RuleContext} context The ESLint rule context object. | |
| * @param {boolean} includeExports Whether or not to check for exports in addition to imports. | |
| * @param {string[]} importsInFile The array containing other imports in the file. | |
| * @param {string[]} exportsInFile The array containing other exports in the file. | |
| * | |
| * @returns {nodeCallback} A function passed to ESLint to handle the statement. | |
| */ | |
| function handleImports(context, includeExports, importsInFile, exportsInFile) { | |
| return function(node) { | |
| const value = getValue(node); | |
| if (value) { | |
| checkAndReport(context, node, value, importsInFile, "import"); | |
| if (includeExports) { | |
| checkAndReport(context, node, value, exportsInFile, "importAs"); | |
| } | |
| importsInFile.push(value); | |
| } | |
| }; | |
| } | |
| /** | |
| * Returns a function handling the exports of a given file | |
| * @param {RuleContext} context The ESLint rule context object. | |
| * @param {string[]} importsInFile The array containing other imports in the file. | |
| * @param {string[]} exportsInFile The array containing other exports in the file. | |
| * | |
| * @returns {nodeCallback} A function passed to ESLint to handle the statement. | |
| */ | |
| function handleExports(context, importsInFile, exportsInFile) { | |
| return function(node) { | |
| const value = getValue(node); | |
| if (value) { | |
| checkAndReport(context, node, value, exportsInFile, "export"); | |
| checkAndReport(context, node, value, importsInFile, "exportAs"); | |
| exportsInFile.push(value); | |
| } | |
| }; | |
| } | |
| module.exports = { | |
| meta: { | |
| type: "problem", | |
| docs: { | |
| description: "disallow duplicate module imports", | |
| category: "ECMAScript 6", | |
| recommended: false, | |
| url: "https://eslint.org/docs/rules/no-duplicate-imports" | |
| }, | |
| schema: [{ | |
| type: "object", | |
| properties: { | |
| includeExports: { | |
| type: "boolean", | |
| default: false | |
| } | |
| }, | |
| additionalProperties: false | |
| }], | |
| messages: { | |
| import: "'{{module}}' import is duplicated.", | |
| importAs: "'{{module}}' import is duplicated as export.", | |
| export: "'{{module}}' export is duplicated.", | |
| exportAs: "'{{module}}' export is duplicated as import." | |
| } | |
| }, | |
| create(context) { | |
| const includeExports = (context.options[0] || {}).includeExports, | |
| importsInFile = [], | |
| exportsInFile = []; | |
| const handlers = { | |
| ImportDeclaration: handleImports(context, includeExports, importsInFile, exportsInFile) | |
| }; | |
| if (includeExports) { | |
| handlers.ExportNamedDeclaration = handleExports(context, importsInFile, exportsInFile); | |
| handlers.ExportAllDeclaration = handleExports(context, importsInFile, exportsInFile); | |
| } | |
| return handlers; | |
| } | |
| }; |