237 lines
10 KiB
JavaScript
237 lines
10 KiB
JavaScript
/**
|
|
* @fileoverview Rule to require braces in arrow function body.
|
|
* @author Alberto Rodríguez
|
|
*/
|
|
"use strict";
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Requirements
|
|
//------------------------------------------------------------------------------
|
|
|
|
const astUtils = require("../ast-utils");
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Rule Definition
|
|
//------------------------------------------------------------------------------
|
|
|
|
module.exports = {
|
|
meta: {
|
|
docs: {
|
|
description: "require braces around arrow function bodies",
|
|
category: "ECMAScript 6",
|
|
recommended: false,
|
|
url: "https://eslint.org/docs/rules/arrow-body-style"
|
|
},
|
|
|
|
schema: {
|
|
anyOf: [
|
|
{
|
|
type: "array",
|
|
items: [
|
|
{
|
|
enum: ["always", "never"]
|
|
}
|
|
],
|
|
minItems: 0,
|
|
maxItems: 1
|
|
},
|
|
{
|
|
type: "array",
|
|
items: [
|
|
{
|
|
enum: ["as-needed"]
|
|
},
|
|
{
|
|
type: "object",
|
|
properties: {
|
|
requireReturnForObjectLiteral: { type: "boolean" }
|
|
},
|
|
additionalProperties: false
|
|
}
|
|
],
|
|
minItems: 0,
|
|
maxItems: 2
|
|
}
|
|
]
|
|
},
|
|
|
|
fixable: "code",
|
|
|
|
messages: {
|
|
unexpectedOtherBlock: "Unexpected block statement surrounding arrow body.",
|
|
unexpectedEmptyBlock: "Unexpected block statement surrounding arrow body; put a value of `undefined` immediately after the `=>`.",
|
|
unexpectedObjectBlock: "Unexpected block statement surrounding arrow body; parenthesize the returned value and move it immediately after the `=>`.",
|
|
unexpectedSingleBlock: "Unexpected block statement surrounding arrow body; move the returned value immediately after the `=>`.",
|
|
expectedBlock: "Expected block statement surrounding arrow body."
|
|
}
|
|
},
|
|
|
|
create(context) {
|
|
const options = context.options;
|
|
const always = options[0] === "always";
|
|
const asNeeded = !options[0] || options[0] === "as-needed";
|
|
const never = options[0] === "never";
|
|
const requireReturnForObjectLiteral = options[1] && options[1].requireReturnForObjectLiteral;
|
|
const sourceCode = context.getSourceCode();
|
|
|
|
/**
|
|
* Checks whether the given node has ASI problem or not.
|
|
* @param {Token} token The token to check.
|
|
* @returns {boolean} `true` if it changes semantics if `;` or `}` followed by the token are removed.
|
|
*/
|
|
function hasASIProblem(token) {
|
|
return token && token.type === "Punctuator" && /^[([/`+-]/.test(token.value);
|
|
}
|
|
|
|
/**
|
|
* Gets the closing parenthesis which is the pair of the given opening parenthesis.
|
|
* @param {Token} token The opening parenthesis token to get.
|
|
* @returns {Token} The found closing parenthesis token.
|
|
*/
|
|
function findClosingParen(token) {
|
|
let node = sourceCode.getNodeByRangeIndex(token.range[1]);
|
|
|
|
while (!astUtils.isParenthesised(sourceCode, node)) {
|
|
node = node.parent;
|
|
}
|
|
return sourceCode.getTokenAfter(node);
|
|
}
|
|
|
|
/**
|
|
* Determines whether a arrow function body needs braces
|
|
* @param {ASTNode} node The arrow function node.
|
|
* @returns {void}
|
|
*/
|
|
function validate(node) {
|
|
const arrowBody = node.body;
|
|
|
|
if (arrowBody.type === "BlockStatement") {
|
|
const blockBody = arrowBody.body;
|
|
|
|
if (blockBody.length !== 1 && !never) {
|
|
return;
|
|
}
|
|
|
|
if (asNeeded && requireReturnForObjectLiteral && blockBody[0].type === "ReturnStatement" &&
|
|
blockBody[0].argument && blockBody[0].argument.type === "ObjectExpression") {
|
|
return;
|
|
}
|
|
|
|
if (never || asNeeded && blockBody[0].type === "ReturnStatement") {
|
|
let messageId;
|
|
|
|
if (blockBody.length === 0) {
|
|
messageId = "unexpectedEmptyBlock";
|
|
} else if (blockBody.length > 1) {
|
|
messageId = "unexpectedOtherBlock";
|
|
} else if (astUtils.isOpeningBraceToken(sourceCode.getFirstToken(blockBody[0], { skip: 1 }))) {
|
|
messageId = "unexpectedObjectBlock";
|
|
} else {
|
|
messageId = "unexpectedSingleBlock";
|
|
}
|
|
|
|
context.report({
|
|
node,
|
|
loc: arrowBody.loc.start,
|
|
messageId,
|
|
fix(fixer) {
|
|
const fixes = [];
|
|
|
|
if (blockBody.length !== 1 ||
|
|
blockBody[0].type !== "ReturnStatement" ||
|
|
!blockBody[0].argument ||
|
|
hasASIProblem(sourceCode.getTokenAfter(arrowBody))
|
|
) {
|
|
return fixes;
|
|
}
|
|
|
|
const openingBrace = sourceCode.getFirstToken(arrowBody);
|
|
const closingBrace = sourceCode.getLastToken(arrowBody);
|
|
const firstValueToken = sourceCode.getFirstToken(blockBody[0], 1);
|
|
const lastValueToken = sourceCode.getLastToken(blockBody[0]);
|
|
const commentsExist =
|
|
sourceCode.commentsExistBetween(openingBrace, firstValueToken) ||
|
|
sourceCode.commentsExistBetween(lastValueToken, closingBrace);
|
|
|
|
/*
|
|
* Remove tokens around the return value.
|
|
* If comments don't exist, remove extra spaces as well.
|
|
*/
|
|
if (commentsExist) {
|
|
fixes.push(
|
|
fixer.remove(openingBrace),
|
|
fixer.remove(closingBrace),
|
|
fixer.remove(sourceCode.getTokenAfter(openingBrace)) // return keyword
|
|
);
|
|
} else {
|
|
fixes.push(
|
|
fixer.removeRange([openingBrace.range[0], firstValueToken.range[0]]),
|
|
fixer.removeRange([lastValueToken.range[1], closingBrace.range[1]])
|
|
);
|
|
}
|
|
|
|
/*
|
|
* If the first token of the reutrn value is `{`,
|
|
* enclose the return value by parentheses to avoid syntax error.
|
|
*/
|
|
if (astUtils.isOpeningBraceToken(firstValueToken)) {
|
|
fixes.push(
|
|
fixer.insertTextBefore(firstValueToken, "("),
|
|
fixer.insertTextAfter(lastValueToken, ")")
|
|
);
|
|
}
|
|
|
|
/*
|
|
* If the last token of the return statement is semicolon, remove it.
|
|
* Non-block arrow body is an expression, not a statement.
|
|
*/
|
|
if (astUtils.isSemicolonToken(lastValueToken)) {
|
|
fixes.push(fixer.remove(lastValueToken));
|
|
}
|
|
|
|
return fixes;
|
|
}
|
|
});
|
|
}
|
|
} else {
|
|
if (always || (asNeeded && requireReturnForObjectLiteral && arrowBody.type === "ObjectExpression")) {
|
|
context.report({
|
|
node,
|
|
loc: arrowBody.loc.start,
|
|
messageId: "expectedBlock",
|
|
fix(fixer) {
|
|
const fixes = [];
|
|
const arrowToken = sourceCode.getTokenBefore(arrowBody, astUtils.isArrowToken);
|
|
const firstBodyToken = sourceCode.getTokenAfter(arrowToken);
|
|
const lastBodyToken = sourceCode.getLastToken(node);
|
|
const isParenthesisedObjectLiteral =
|
|
astUtils.isOpeningParenToken(firstBodyToken) &&
|
|
astUtils.isOpeningBraceToken(sourceCode.getTokenAfter(firstBodyToken));
|
|
|
|
// Wrap the value by a block and a return statement.
|
|
fixes.push(
|
|
fixer.insertTextBefore(firstBodyToken, "{return "),
|
|
fixer.insertTextAfter(lastBodyToken, "}")
|
|
);
|
|
|
|
// If the value is object literal, remove parentheses which were forced by syntax.
|
|
if (isParenthesisedObjectLiteral) {
|
|
fixes.push(
|
|
fixer.remove(firstBodyToken),
|
|
fixer.remove(findClosingParen(firstBodyToken))
|
|
);
|
|
}
|
|
|
|
return fixes;
|
|
}
|
|
});
|
|
}
|
|
}
|
|
}
|
|
|
|
return {
|
|
"ArrowFunctionExpression:exit": validate
|
|
};
|
|
}
|
|
};
|