419 lines
10 KiB
JavaScript
419 lines
10 KiB
JavaScript
/**
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* @fileoverview Rule to require braces in arrow function body.
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* @author Alberto Rodríguez
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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("./utils/ast-utils");
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//------------------------------------------------------------------------------
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// Rule Definition
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//------------------------------------------------------------------------------
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/** @type {import('../types').Rule.RuleModule} */
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module.exports = {
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meta: {
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type: "suggestion",
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defaultOptions: ["as-needed"],
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docs: {
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description: "Require braces around arrow function bodies",
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recommended: false,
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frozen: true,
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url: "https://eslint.org/docs/latest/rules/arrow-body-style",
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},
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schema: {
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anyOf: [
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{
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type: "array",
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items: [
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{
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enum: ["always", "never"],
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},
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],
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minItems: 0,
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maxItems: 1,
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},
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{
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type: "array",
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items: [
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{
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enum: ["as-needed"],
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},
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{
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type: "object",
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properties: {
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requireReturnForObjectLiteral: {
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type: "boolean",
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},
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},
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additionalProperties: false,
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},
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],
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minItems: 0,
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maxItems: 2,
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},
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],
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},
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fixable: "code",
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messages: {
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unexpectedOtherBlock:
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"Unexpected block statement surrounding arrow body.",
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unexpectedEmptyBlock:
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"Unexpected block statement surrounding arrow body; put a value of `undefined` immediately after the `=>`.",
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unexpectedObjectBlock:
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"Unexpected block statement surrounding arrow body; parenthesize the returned value and move it immediately after the `=>`.",
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unexpectedSingleBlock:
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"Unexpected block statement surrounding arrow body; move the returned value immediately after the `=>`.",
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expectedBlock: "Expected block statement surrounding arrow body.",
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},
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},
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create(context) {
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const options = context.options;
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const always = options[0] === "always";
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const asNeeded = options[0] === "as-needed";
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const never = options[0] === "never";
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const requireReturnForObjectLiteral =
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options[1] && options[1].requireReturnForObjectLiteral;
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const sourceCode = context.sourceCode;
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let funcInfo = null;
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/**
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* Checks whether the given node has ASI problem or not.
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* @param {Token} token The token to check.
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* @returns {boolean} `true` if it changes semantics if `;` or `}` followed by the token are removed.
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*/
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function hasASIProblem(token) {
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return (
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token &&
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token.type === "Punctuator" &&
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/^[([/`+-]/u.test(token.value)
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);
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}
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/**
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* Gets the closing parenthesis by the given node.
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* @param {ASTNode} node first node after an opening parenthesis.
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* @returns {Token} The found closing parenthesis token.
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*/
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function findClosingParen(node) {
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let nodeToCheck = node;
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while (!astUtils.isParenthesised(sourceCode, nodeToCheck)) {
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nodeToCheck = nodeToCheck.parent;
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}
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return sourceCode.getTokenAfter(nodeToCheck);
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}
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/**
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* Check whether the node is inside of a for loop's init
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* @param {ASTNode} node node is inside for loop
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* @returns {boolean} `true` if the node is inside of a for loop, else `false`
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*/
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function isInsideForLoopInitializer(node) {
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if (node && node.parent) {
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if (
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node.parent.type === "ForStatement" &&
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node.parent.init === node
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) {
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return true;
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}
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return isInsideForLoopInitializer(node.parent);
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}
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return false;
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}
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/**
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* Determines whether a arrow function body needs braces
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* @param {ASTNode} node The arrow function node.
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* @returns {void}
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*/
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function validate(node) {
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const arrowBody = node.body;
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if (arrowBody.type === "BlockStatement") {
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const blockBody = arrowBody.body;
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if (blockBody.length !== 1 && !never) {
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return;
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}
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if (
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asNeeded &&
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requireReturnForObjectLiteral &&
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blockBody[0].type === "ReturnStatement" &&
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blockBody[0].argument &&
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blockBody[0].argument.type === "ObjectExpression"
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) {
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return;
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}
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if (
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never ||
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(asNeeded && blockBody[0].type === "ReturnStatement")
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) {
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let messageId;
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if (blockBody.length === 0) {
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messageId = "unexpectedEmptyBlock";
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} else if (
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blockBody.length > 1 ||
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blockBody[0].type !== "ReturnStatement"
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) {
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messageId = "unexpectedOtherBlock";
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} else if (blockBody[0].argument === null) {
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messageId = "unexpectedSingleBlock";
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} else if (
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astUtils.isOpeningBraceToken(
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sourceCode.getFirstToken(blockBody[0], { skip: 1 }),
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)
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) {
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messageId = "unexpectedObjectBlock";
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} else {
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messageId = "unexpectedSingleBlock";
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}
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context.report({
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node,
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loc: arrowBody.loc,
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messageId,
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fix(fixer) {
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const fixes = [];
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if (
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blockBody.length !== 1 ||
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blockBody[0].type !== "ReturnStatement" ||
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!blockBody[0].argument ||
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hasASIProblem(
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sourceCode.getTokenAfter(arrowBody),
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)
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) {
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return fixes;
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}
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const openingBrace =
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sourceCode.getFirstToken(arrowBody);
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const closingBrace =
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sourceCode.getLastToken(arrowBody);
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const firstValueToken = sourceCode.getFirstToken(
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blockBody[0],
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1,
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);
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const lastValueToken = sourceCode.getLastToken(
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blockBody[0],
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);
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const commentsExist =
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sourceCode.commentsExistBetween(
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openingBrace,
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firstValueToken,
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) ||
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sourceCode.commentsExistBetween(
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lastValueToken,
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closingBrace,
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);
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/*
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* Remove tokens around the return value.
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* If comments don't exist, remove extra spaces as well.
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*/
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if (commentsExist) {
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fixes.push(
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fixer.remove(openingBrace),
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fixer.remove(closingBrace),
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fixer.remove(
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sourceCode.getTokenAfter(openingBrace),
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), // return keyword
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);
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} else {
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fixes.push(
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fixer.removeRange([
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openingBrace.range[0],
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firstValueToken.range[0],
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]),
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fixer.removeRange([
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lastValueToken.range[1],
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closingBrace.range[1],
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]),
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);
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}
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/*
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* If the first token of the return value is `{` or the return value is a sequence expression,
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* enclose the return value by parentheses to avoid syntax error.
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*/
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if (
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astUtils.isOpeningBraceToken(firstValueToken) ||
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blockBody[0].argument.type ===
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"SequenceExpression" ||
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(funcInfo.hasInOperator &&
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isInsideForLoopInitializer(node))
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) {
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if (
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!astUtils.isParenthesised(
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sourceCode,
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blockBody[0].argument,
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)
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) {
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fixes.push(
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fixer.insertTextBefore(
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firstValueToken,
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"(",
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),
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fixer.insertTextAfter(
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lastValueToken,
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")",
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),
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);
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}
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}
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/*
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* If the last token of the return statement is semicolon, remove it.
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* Non-block arrow body is an expression, not a statement.
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*/
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if (astUtils.isSemicolonToken(lastValueToken)) {
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fixes.push(fixer.remove(lastValueToken));
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}
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return fixes;
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},
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});
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}
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} else {
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if (
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always ||
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(asNeeded &&
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requireReturnForObjectLiteral &&
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arrowBody.type === "ObjectExpression")
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) {
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context.report({
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node,
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loc: arrowBody.loc,
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messageId: "expectedBlock",
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fix(fixer) {
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const fixes = [];
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const arrowToken = sourceCode.getTokenBefore(
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arrowBody,
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astUtils.isArrowToken,
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);
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const [
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firstTokenAfterArrow,
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secondTokenAfterArrow,
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] = sourceCode.getTokensAfter(arrowToken, {
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count: 2,
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});
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const lastToken = sourceCode.getLastToken(node);
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let parenthesisedObjectLiteral = null;
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if (
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astUtils.isOpeningParenToken(
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firstTokenAfterArrow,
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) &&
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astUtils.isOpeningBraceToken(
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secondTokenAfterArrow,
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)
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) {
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const braceNode =
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sourceCode.getNodeByRangeIndex(
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secondTokenAfterArrow.range[0],
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);
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if (braceNode.type === "ObjectExpression") {
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parenthesisedObjectLiteral = braceNode;
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}
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}
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// If the value is object literal, remove parentheses which were forced by syntax.
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if (parenthesisedObjectLiteral) {
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const openingParenToken = firstTokenAfterArrow;
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const openingBraceToken = secondTokenAfterArrow;
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if (
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astUtils.isTokenOnSameLine(
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openingParenToken,
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openingBraceToken,
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)
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) {
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fixes.push(
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fixer.replaceText(
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openingParenToken,
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"{return ",
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),
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);
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} else {
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// Avoid ASI
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fixes.push(
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fixer.replaceText(
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openingParenToken,
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"{",
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),
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fixer.insertTextBefore(
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openingBraceToken,
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"return ",
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),
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);
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}
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// Closing paren for the object doesn't have to be lastToken, e.g.: () => ({}).foo()
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fixes.push(
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fixer.remove(
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findClosingParen(
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parenthesisedObjectLiteral,
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),
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),
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);
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fixes.push(
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fixer.insertTextAfter(lastToken, "}"),
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);
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} else {
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fixes.push(
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fixer.insertTextBefore(
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firstTokenAfterArrow,
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"{return ",
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),
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);
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fixes.push(
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fixer.insertTextAfter(lastToken, "}"),
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);
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}
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return fixes;
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},
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});
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}
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}
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}
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return {
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"BinaryExpression[operator='in']"() {
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let info = funcInfo;
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while (info) {
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info.hasInOperator = true;
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info = info.upper;
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}
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},
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ArrowFunctionExpression() {
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funcInfo = {
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upper: funcInfo,
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hasInOperator: false,
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};
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},
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"ArrowFunctionExpression:exit"(node) {
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validate(node);
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funcInfo = funcInfo.upper;
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},
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};
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},
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};
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