124 lines
3.6 KiB
JavaScript
124 lines
3.6 KiB
JavaScript
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/**
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* @fileoverview A rule to disallow `this` keywords outside of classes or class-like objects.
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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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// Requirements
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//------------------------------------------------------------------------------
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const astUtils = require("../ast-utils");
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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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docs: {
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description: "disallow `this` keywords outside of classes or class-like objects",
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category: "Best Practices",
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recommended: false
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},
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schema: []
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},
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create(context) {
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const stack = [],
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sourceCode = context.getSourceCode();
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/**
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* Gets the current checking context.
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*
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* The return value has a flag that whether or not `this` keyword is valid.
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* The flag is initialized when got at the first time.
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*
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* @returns {{valid: boolean}}
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* an object which has a flag that whether or not `this` keyword is valid.
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*/
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stack.getCurrent = function() {
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const current = this[this.length - 1];
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if (!current.init) {
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current.init = true;
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current.valid = !astUtils.isDefaultThisBinding(
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current.node,
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sourceCode
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);
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}
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return current;
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};
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/**
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* Pushs new checking context into the stack.
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*
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* The checking context is not initialized yet.
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* Because most functions don't have `this` keyword.
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* When `this` keyword was found, the checking context is initialized.
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*
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* @param {ASTNode} node - A function node that was entered.
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* @returns {void}
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*/
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function enterFunction(node) {
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// `this` can be invalid only under strict mode.
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stack.push({
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init: !context.getScope().isStrict,
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node,
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valid: true
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});
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}
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/**
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* Pops the current checking context from the stack.
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* @returns {void}
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*/
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function exitFunction() {
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stack.pop();
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}
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return {
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/*
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* `this` is invalid only under strict mode.
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* Modules is always strict mode.
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*/
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Program(node) {
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const scope = context.getScope(),
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features = context.parserOptions.ecmaFeatures || {};
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stack.push({
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init: true,
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node,
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valid: !(
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scope.isStrict ||
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node.sourceType === "module" ||
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(features.globalReturn && scope.childScopes[0].isStrict)
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)
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});
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},
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"Program:exit"() {
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stack.pop();
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},
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FunctionDeclaration: enterFunction,
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"FunctionDeclaration:exit": exitFunction,
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FunctionExpression: enterFunction,
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"FunctionExpression:exit": exitFunction,
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// Reports if `this` of the current context is invalid.
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ThisExpression(node) {
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const current = stack.getCurrent();
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if (current && !current.valid) {
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context.report({ node, message: "Unexpected 'this'." });
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}
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}
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};
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}
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};
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