/**
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* @fileoverview Rule to flag duplicate arguments
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* @author Jamund Ferguson
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*/
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"use strict";
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//------------------------------------------------------------------------------
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// Rule Definition
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//------------------------------------------------------------------------------
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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 arguments in `function` definitions",
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category: "Possible Errors",
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recommended: true,
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url: "https://eslint.org/docs/rules/no-dupe-args"
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},
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schema: [],
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messages: {
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unexpected: "Duplicate param '{{name}}'."
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}
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},
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create(context) {
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//--------------------------------------------------------------------------
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// Helpers
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//--------------------------------------------------------------------------
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/**
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* Checks whether or not a given definition is a parameter's.
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* @param {eslint-scope.DefEntry} def A definition to check.
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* @returns {boolean} `true` if the definition is a parameter's.
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*/
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function isParameter(def) {
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return def.type === "Parameter";
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}
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/**
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* Determines if a given node has duplicate parameters.
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* @param {ASTNode} node The node to check.
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* @returns {void}
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* @private
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*/
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function checkParams(node) {
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const variables = context.getDeclaredVariables(node);
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for (let i = 0; i < variables.length; ++i) {
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const variable = variables[i];
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// Checks and reports duplications.
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const defs = variable.defs.filter(isParameter);
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if (defs.length >= 2) {
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context.report({
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node,
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messageId: "unexpected",
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data: { name: variable.name }
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});
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}
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}
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}
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//--------------------------------------------------------------------------
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// Public API
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//--------------------------------------------------------------------------
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return {
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FunctionDeclaration: checkParams,
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FunctionExpression: checkParams
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};
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}
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};
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