1/** 2 * @fileoverview A rule to disallow duplicate name in class members. 3 * @author Toru Nagashima 4 */ 5 6"use strict"; 7 8const astUtils = require("./utils/ast-utils"); 9 10//------------------------------------------------------------------------------ 11// Rule Definition 12//------------------------------------------------------------------------------ 13 14module.exports = { 15 meta: { 16 type: "problem", 17 18 docs: { 19 description: "disallow duplicate class members", 20 category: "ECMAScript 6", 21 recommended: true, 22 url: "https://eslint.org/docs/rules/no-dupe-class-members" 23 }, 24 25 schema: [], 26 27 messages: { 28 unexpected: "Duplicate name '{{name}}'." 29 } 30 }, 31 32 create(context) { 33 let stack = []; 34 35 /** 36 * Gets state of a given member name. 37 * @param {string} name A name of a member. 38 * @param {boolean} isStatic A flag which specifies that is a static member. 39 * @returns {Object} A state of a given member name. 40 * - retv.init {boolean} A flag which shows the name is declared as normal member. 41 * - retv.get {boolean} A flag which shows the name is declared as getter. 42 * - retv.set {boolean} A flag which shows the name is declared as setter. 43 */ 44 function getState(name, isStatic) { 45 const stateMap = stack[stack.length - 1]; 46 const key = `$${name}`; // to avoid "__proto__". 47 48 if (!stateMap[key]) { 49 stateMap[key] = { 50 nonStatic: { init: false, get: false, set: false }, 51 static: { init: false, get: false, set: false } 52 }; 53 } 54 55 return stateMap[key][isStatic ? "static" : "nonStatic"]; 56 } 57 58 return { 59 60 // Initializes the stack of state of member declarations. 61 Program() { 62 stack = []; 63 }, 64 65 // Initializes state of member declarations for the class. 66 ClassBody() { 67 stack.push(Object.create(null)); 68 }, 69 70 // Disposes the state for the class. 71 "ClassBody:exit"() { 72 stack.pop(); 73 }, 74 75 // Reports the node if its name has been declared already. 76 MethodDefinition(node) { 77 const name = astUtils.getStaticPropertyName(node); 78 79 if (name === null || node.kind === "constructor") { 80 return; 81 } 82 83 const state = getState(name, node.static); 84 let isDuplicate = false; 85 86 if (node.kind === "get") { 87 isDuplicate = (state.init || state.get); 88 state.get = true; 89 } else if (node.kind === "set") { 90 isDuplicate = (state.init || state.set); 91 state.set = true; 92 } else { 93 isDuplicate = (state.init || state.get || state.set); 94 state.init = true; 95 } 96 97 if (isDuplicate) { 98 context.report({ node, messageId: "unexpected", data: { name } }); 99 } 100 } 101 }; 102 } 103}; 104