116 lines
3.3 KiB
JavaScript
116 lines
3.3 KiB
JavaScript
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/**
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* @fileoverview Rule to
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* @author Toru Nagashima
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*/
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"use strict";
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//------------------------------------------------------------------------------
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// Helpers
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//------------------------------------------------------------------------------
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/**
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* Gets the variable object of `arguments` which is defined implicitly.
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* @param {eslint-scope.Scope} scope A scope to get.
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* @returns {eslint-scope.Variable} The found variable object.
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*/
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function getVariableOfArguments(scope) {
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const variables = scope.variables;
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for (let i = 0; i < variables.length; ++i) {
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const variable = variables[i];
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if (variable.name === "arguments") {
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/*
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* If there was a parameter which is named "arguments", the implicit "arguments" is not defined.
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* So does fast return with null.
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*/
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return (variable.identifiers.length === 0) ? variable : null;
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}
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}
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/* istanbul ignore next : unreachable */
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return null;
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}
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/**
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* Checks if the given reference is not normal member access.
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*
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* - arguments .... true // not member access
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* - arguments[i] .... true // computed member access
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* - arguments[0] .... true // computed member access
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* - arguments.length .... false // normal member access
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* @param {eslint-scope.Reference} reference The reference to check.
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* @returns {boolean} `true` if the reference is not normal member access.
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*/
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function isNotNormalMemberAccess(reference) {
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const id = reference.identifier;
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const parent = id.parent;
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return !(
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parent.type === "MemberExpression" &&
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parent.object === id &&
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!parent.computed
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);
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}
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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: "suggestion",
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docs: {
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description: "require rest parameters instead of `arguments`",
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category: "ECMAScript 6",
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recommended: false,
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url: "https://eslint.org/docs/rules/prefer-rest-params"
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},
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schema: [],
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messages: {
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preferRestParams: "Use the rest parameters instead of 'arguments'."
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}
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},
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create(context) {
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/**
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* Reports a given reference.
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* @param {eslint-scope.Reference} reference A reference to report.
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* @returns {void}
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*/
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function report(reference) {
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context.report({
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node: reference.identifier,
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loc: reference.identifier.loc,
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messageId: "preferRestParams"
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});
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}
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/**
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* Reports references of the implicit `arguments` variable if exist.
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* @returns {void}
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*/
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function checkForArguments() {
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const argumentsVar = getVariableOfArguments(context.getScope());
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if (argumentsVar) {
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argumentsVar
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.references
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.filter(isNotNormalMemberAccess)
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.forEach(report);
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}
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}
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return {
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"FunctionDeclaration:exit": checkForArguments,
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"FunctionExpression:exit": checkForArguments
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};
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}
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};
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