no-dupe-args.js
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/**
* @fileoverview Rule to flag duplicate arguments
* @author Jamund Ferguson
* @copyright 2015 Jamund Ferguson. All rights reserved.
* @copyright 2015 Toru Nagashima. All rights reserved.
* See LICENSE file in root directory for full license.
*/
"use strict";
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
module.exports = function(context) {
//--------------------------------------------------------------------------
// Helpers
//--------------------------------------------------------------------------
/**
* Checks whether or not a given definition is a parameter's.
* @param {escope.DefEntry} def - A definition to check.
* @returns {boolean} `true` if the definition is a parameter's.
*/
function isParameter(def) {
return def.type === "Parameter";
}
/**
* Determines if a given node has duplicate parameters.
* @param {ASTNode} node The node to check.
* @returns {void}
* @private
*/
function checkParams(node) {
var variables = context.getDeclaredVariables(node);
var keyMap = Object.create(null);
for (var i = 0; i < variables.length; ++i) {
var variable = variables[i];
// TODO(nagashima): Remove this duplication check after https://github.com/estools/escope/pull/79
var key = "$" + variable.name; // to avoid __proto__.
if (!isParameter(variable.defs[0]) || keyMap[key]) {
continue;
}
keyMap[key] = true;
// Checks and reports duplications.
var defs = variable.defs.filter(isParameter);
if (defs.length >= 2) {
context.report({
node: node,
message: "Duplicate param '{{name}}'.",
data: {name: variable.name}
});
}
}
}
//--------------------------------------------------------------------------
// Public API
//--------------------------------------------------------------------------
return {
"FunctionDeclaration": checkParams,
"FunctionExpression": checkParams
};
};
module.exports.schema = [];