Current File : /var/www/html/node_modules/eslint/lib/rules/arrow-parens.js
/**
* @fileoverview Rule to require parens in arrow function arguments.
* @author Jxck
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const astUtils = require("./utils/ast-utils");
//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------
/**
* Determines if the given arrow function has block body.
* @param {ASTNode} node `ArrowFunctionExpression` node.
* @returns {boolean} `true` if the function has block body.
*/
function hasBlockBody(node) {
return node.body.type === "BlockStatement";
}
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
/** @type {import('../shared/types').Rule} */
module.exports = {
meta: {
type: "layout",
docs: {
description: "require parentheses around arrow function arguments",
recommended: false,
url: "https://eslint.org/docs/rules/arrow-parens"
},
fixable: "code",
schema: [
{
enum: ["always", "as-needed"]
},
{
type: "object",
properties: {
requireForBlockBody: {
type: "boolean",
default: false
}
},
additionalProperties: false
}
],
messages: {
unexpectedParens: "Unexpected parentheses around single function argument.",
expectedParens: "Expected parentheses around arrow function argument.",
unexpectedParensInline: "Unexpected parentheses around single function argument having a body with no curly braces.",
expectedParensBlock: "Expected parentheses around arrow function argument having a body with curly braces."
}
},
create(context) {
const asNeeded = context.options[0] === "as-needed";
const requireForBlockBody = asNeeded && context.options[1] && context.options[1].requireForBlockBody === true;
const sourceCode = context.getSourceCode();
/**
* Finds opening paren of parameters for the given arrow function, if it exists.
* It is assumed that the given arrow function has exactly one parameter.
* @param {ASTNode} node `ArrowFunctionExpression` node.
* @returns {Token|null} the opening paren, or `null` if the given arrow function doesn't have parens of parameters.
*/
function findOpeningParenOfParams(node) {
const tokenBeforeParams = sourceCode.getTokenBefore(node.params[0]);
if (
tokenBeforeParams &&
astUtils.isOpeningParenToken(tokenBeforeParams) &&
node.range[0] <= tokenBeforeParams.range[0]
) {
return tokenBeforeParams;
}
return null;
}
/**
* Finds closing paren of parameters for the given arrow function.
* It is assumed that the given arrow function has parens of parameters and that it has exactly one parameter.
* @param {ASTNode} node `ArrowFunctionExpression` node.
* @returns {Token} the closing paren of parameters.
*/
function getClosingParenOfParams(node) {
return sourceCode.getTokenAfter(node.params[0], astUtils.isClosingParenToken);
}
/**
* Determines whether the given arrow function has comments inside parens of parameters.
* It is assumed that the given arrow function has parens of parameters.
* @param {ASTNode} node `ArrowFunctionExpression` node.
* @param {Token} openingParen Opening paren of parameters.
* @returns {boolean} `true` if the function has at least one comment inside of parens of parameters.
*/
function hasCommentsInParensOfParams(node, openingParen) {
return sourceCode.commentsExistBetween(openingParen, getClosingParenOfParams(node));
}
/**
* Determines whether the given arrow function has unexpected tokens before opening paren of parameters,
* in which case it will be assumed that the existing parens of parameters are necessary.
* Only tokens within the range of the arrow function (tokens that are part of the arrow function) are taken into account.
* Example: <T>(a) => b
* @param {ASTNode} node `ArrowFunctionExpression` node.
* @param {Token} openingParen Opening paren of parameters.
* @returns {boolean} `true` if the function has at least one unexpected token.
*/
function hasUnexpectedTokensBeforeOpeningParen(node, openingParen) {
const expectedCount = node.async ? 1 : 0;
return sourceCode.getFirstToken(node, { skip: expectedCount }) !== openingParen;
}
return {
"ArrowFunctionExpression[params.length=1]"(node) {
const shouldHaveParens = !asNeeded || requireForBlockBody && hasBlockBody(node);
const openingParen = findOpeningParenOfParams(node);
const hasParens = openingParen !== null;
const [param] = node.params;
if (shouldHaveParens && !hasParens) {
context.report({
node,
messageId: requireForBlockBody ? "expectedParensBlock" : "expectedParens",
loc: param.loc,
*fix(fixer) {
yield fixer.insertTextBefore(param, "(");
yield fixer.insertTextAfter(param, ")");
}
});
}
if (
!shouldHaveParens &&
hasParens &&
param.type === "Identifier" &&
!param.typeAnnotation &&
!node.returnType &&
!hasCommentsInParensOfParams(node, openingParen) &&
!hasUnexpectedTokensBeforeOpeningParen(node, openingParen)
) {
context.report({
node,
messageId: requireForBlockBody ? "unexpectedParensInline" : "unexpectedParens",
loc: param.loc,
*fix(fixer) {
const tokenBeforeOpeningParen = sourceCode.getTokenBefore(openingParen);
const closingParen = getClosingParenOfParams(node);
if (
tokenBeforeOpeningParen &&
tokenBeforeOpeningParen.range[1] === openingParen.range[0] &&
!astUtils.canTokensBeAdjacent(tokenBeforeOpeningParen, sourceCode.getFirstToken(param))
) {
yield fixer.insertTextBefore(openingParen, " ");
}
// remove parens, whitespace inside parens, and possible trailing comma
yield fixer.removeRange([openingParen.range[0], param.range[0]]);
yield fixer.removeRange([param.range[1], closingParen.range[1]]);
}
});
}
}
};
}
};
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