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/**
* @author Toru Nagashima <https://github.com/mysticatea>
* See LICENSE file in root directory for full license.
*/
"use strict"
const { isArrowToken } = require("eslint-utils")
module.exports = {
meta: {
docs: {
description: "disallow arrow function expressions.",
category: "ES2015",
recommended: false,
url:
"http://mysticatea.github.io/eslint-plugin-es/rules/no-arrow-functions.html",
},
fixable: "code",
schema: [],
messages: {
forbidden: "ES2015 arrow function expressions are forbidden.",
},
},
create(context) {
const sourceCode = context.getSourceCode()
/**
* ArrowFunctionExpression to FunctionExpression
* @param {Node} node ArrowFunctionExpression Node
* @returns {string} function expression text
*/
function toFunctionExpression(node) {
const params = node.params
const paramText = params.length
? sourceCode.text.slice(
params[0].range[0],
params[params.length - 1].range[1]
)
: ""
const arrowToken = sourceCode.getTokenBefore(
node.body,
isArrowToken
)
const preText = sourceCode.text.slice(
arrowToken.range[1],
node.body.range[0]
)
const bodyText = sourceCode.text.slice(
arrowToken.range[1],
node.range[1]
)
if (node.body.type === "BlockStatement") {
return `function(${paramText})${bodyText}`
}
if (preText.includes("\n")) {
return `function(${paramText}){return(${bodyText})}`
}
return `function(${paramText}){return ${bodyText}}`
}
/**
* Report that ArrowFunctionExpression is being used
* @param {Node} node ArrowFunctionExpression Node
* @param {boolean} hasThis Whether `this` is referenced in` function` scope
* @param {boolean} hasSuper Whether `super` is referenced in` function` scope
* @returns {void}
*/
function report(node, hasThis, hasSuper) {
context.report({
node,
messageId: "forbidden",
fix(fixer) {
if (hasSuper) {
return undefined
}
const functionText = toFunctionExpression(node)
return fixer.replaceText(
node,
hasThis ? `${functionText}.bind(this)` : functionText
)
},
})
}
let stack = { upper: null, hasThis: false, hasSuper: false }
return {
":function"() {
stack = { upper: stack, hasThis: false, hasSuper: false }
},
":function:exit"(node) {
const { hasThis, hasSuper } = stack
stack = stack.upper
if (node.type === "ArrowFunctionExpression") {
report(node, hasThis, hasSuper)
stack.hasThis = stack.hasThis || hasThis
stack.hasSuper = stack.hasSuper || hasSuper
}
},
ThisExpression() {
stack.hasThis = true
},
Super() {
stack.hasSuper = true
},
}
},
}