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/**
* @fileoverview Rule to require parens in arrow function arguments.
* @author Jxck
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const astUtils = require("./utils/ast-utils");
//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------
/**
* Get location should be reported by AST node.
*
* @param {ASTNode} node AST Node.
* @returns {Location} Location information.
*/
function getLocation(node) {
return {
start: node.params[0].loc.start,
end: node.params[node.params.length - 1].loc.end
};
}
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
module.exports = {
meta: {
type: "layout",
docs: {
description: "require parentheses around arrow function arguments",
category: "ECMAScript 6",
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();
/**
* Determines whether a arrow function argument end with `)`
* @param {ASTNode} node The arrow function node.
* @returns {void}
*/
function parens(node) {
const isAsync = node.async;
const firstTokenOfParam = sourceCode.getFirstToken(node, isAsync ? 1 : 0);
/**
* Remove the parenthesis around a parameter
* @param {Fixer} fixer Fixer
* @returns {string} fixed parameter
*/
function fixParamsWithParenthesis(fixer) {
const paramToken = sourceCode.getTokenAfter(firstTokenOfParam);
/*
* ES8 allows Trailing commas in function parameter lists and calls
* https://github.com/eslint/eslint/issues/8834
*/
const closingParenToken = sourceCode.getTokenAfter(paramToken, astUtils.isClosingParenToken);
const asyncToken = isAsync ? sourceCode.getTokenBefore(firstTokenOfParam) : null;
const shouldAddSpaceForAsync = asyncToken && (asyncToken.range[1] === firstTokenOfParam.range[0]);
return fixer.replaceTextRange([
firstTokenOfParam.range[0],
closingParenToken.range[1]
], `${shouldAddSpaceForAsync ? " " : ""}${paramToken.value}`);
}
// "as-needed", { "requireForBlockBody": true }: x => x
if (
requireForBlockBody &&
node.params.length === 1 &&
node.params[0].type === "Identifier" &&
!node.params[0].typeAnnotation &&
node.body.type !== "BlockStatement" &&
!node.returnType
) {
if (astUtils.isOpeningParenToken(firstTokenOfParam)) {
context.report({
node,
messageId: "unexpectedParensInline",
loc: getLocation(node),
fix: fixParamsWithParenthesis
});
}
return;
}
if (
requireForBlockBody &&
node.body.type === "BlockStatement"
) {
if (!astUtils.isOpeningParenToken(firstTokenOfParam)) {
context.report({
node,
messageId: "expectedParensBlock",
loc: getLocation(node),
fix(fixer) {
return fixer.replaceText(firstTokenOfParam, `(${firstTokenOfParam.value})`);
}
});
}
return;
}
// "as-needed": x => x
if (asNeeded &&
node.params.length === 1 &&
node.params[0].type === "Identifier" &&
!node.params[0].typeAnnotation &&
!node.returnType
) {
if (astUtils.isOpeningParenToken(firstTokenOfParam)) {
context.report({
node,
messageId: "unexpectedParens",
loc: getLocation(node),
fix: fixParamsWithParenthesis
});
}
return;
}
if (firstTokenOfParam.type === "Identifier") {
const after = sourceCode.getTokenAfter(firstTokenOfParam);
// (x) => x
if (after.value !== ")") {
context.report({
node,
messageId: "expectedParens",
loc: getLocation(node),
fix(fixer) {
return fixer.replaceText(firstTokenOfParam, `(${firstTokenOfParam.value})`);
}
});
}
}
}
return {
ArrowFunctionExpression: parens
};
}
};
|
