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