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qwen/nodejs/node_modules/eslint/lib/rules/no-dupe-class-members.js

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+/**
+ * @fileoverview A rule to disallow duplicate name in class members.
+ * @author Toru Nagashima
+ */
+
+"use strict";
+
+const astUtils = require("./utils/ast-utils");
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+/** @type {import('../shared/types').Rule} */
+module.exports = {
+    meta: {
+        type: "problem",
+
+        docs: {
+            description: "Disallow duplicate class members",
+            recommended: true,
+            url: "https://eslint.org/docs/latest/rules/no-dupe-class-members"
+        },
+
+        schema: [],
+
+        messages: {
+            unexpected: "Duplicate name '{{name}}'."
+        }
+    },
+
+    create(context) {
+        let stack = [];
+
+        /**
+         * Gets state of a given member name.
+         * @param {string} name A name of a member.
+         * @param {boolean} isStatic A flag which specifies that is a static member.
+         * @returns {Object} A state of a given member name.
+         *   - retv.init {boolean} A flag which shows the name is declared as normal member.
+         *   - retv.get {boolean} A flag which shows the name is declared as getter.
+         *   - retv.set {boolean} A flag which shows the name is declared as setter.
+         */
+        function getState(name, isStatic) {
+            const stateMap = stack[stack.length - 1];
+            const key = `$${name}`; // to avoid "__proto__".
+
+            if (!stateMap[key]) {
+                stateMap[key] = {
+                    nonStatic: { init: false, get: false, set: false },
+                    static: { init: false, get: false, set: false }
+                };
+            }
+
+            return stateMap[key][isStatic ? "static" : "nonStatic"];
+        }
+
+        return {
+
+            // Initializes the stack of state of member declarations.
+            Program() {
+                stack = [];
+            },
+
+            // Initializes state of member declarations for the class.
+            ClassBody() {
+                stack.push(Object.create(null));
+            },
+
+            // Disposes the state for the class.
+            "ClassBody:exit"() {
+                stack.pop();
+            },
+
+            // Reports the node if its name has been declared already.
+            "MethodDefinition, PropertyDefinition"(node) {
+                const name = astUtils.getStaticPropertyName(node);
+                const kind = node.type === "MethodDefinition" ? node.kind : "field";
+
+                if (name === null || kind === "constructor") {
+                    return;
+                }
+
+                const state = getState(name, node.static);
+                let isDuplicate = false;
+
+                if (kind === "get") {
+                    isDuplicate = (state.init || state.get);
+                    state.get = true;
+                } else if (kind === "set") {
+                    isDuplicate = (state.init || state.set);
+                    state.set = true;
+                } else {
+                    isDuplicate = (state.init || state.get || state.set);
+                    state.init = true;
+                }
+
+                if (isDuplicate) {
+                    context.report({ node, messageId: "unexpected", data: { name } });
+                }
+            }
+        };
+    }
+};