83 lines
		
	
	
		
			2.4 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
			
		
		
	
	
			83 lines
		
	
	
		
			2.4 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
/**
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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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/** @type {import('../shared/types').Rule} */
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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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            recommended: true,
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            url: "https://eslint.org/docs/latest/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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        const sourceCode = context.sourceCode;
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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 = sourceCode.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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