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/**
* @author Jamund Ferguson
* See LICENSE file in root directory for full license.
*/
"use strict"
module.exports = {
meta: {
docs: {
description: "require `return` statements after callbacks",
category: "Stylistic Issues",
recommended: false,
url:
"https://github.com/mysticatea/eslint-plugin-node/blob/v11.1.0/docs/rules/callback-return.md",
},
fixable: null,
messages: {
missingReturn: "Expected return with your callback function.",
},
schema: [
{
type: "array",
items: { type: "string" },
},
],
type: "suggestion",
},
create(context) {
const callbacks = context.options[0] || ["callback", "cb", "next"]
const sourceCode = context.getSourceCode()
/**
* Find the closest parent matching a list of types.
* @param {ASTNode} node The node whose parents we are searching
* @param {Array} types The node types to match
* @returns {ASTNode} The matched node or undefined.
*/
function findClosestParentOfType(node, types) {
if (!node.parent) {
return null
}
if (types.indexOf(node.parent.type) === -1) {
return findClosestParentOfType(node.parent, types)
}
return node.parent
}
/**
* Check to see if a node contains only identifers
* @param {ASTNode} node The node to check
* @returns {boolean} Whether or not the node contains only identifers
*/
function containsOnlyIdentifiers(node) {
if (node.type === "Identifier") {
return true
}
if (node.type === "MemberExpression") {
if (node.object.type === "Identifier") {
return true
}
if (node.object.type === "MemberExpression") {
return containsOnlyIdentifiers(node.object)
}
}
return false
}
/**
* Check to see if a CallExpression is in our callback list.
* @param {ASTNode} node The node to check against our callback names list.
* @returns {boolean} Whether or not this function matches our callback name.
*/
function isCallback(node) {
return (
containsOnlyIdentifiers(node.callee) &&
callbacks.indexOf(sourceCode.getText(node.callee)) > -1
)
}
/**
* Determines whether or not the callback is part of a callback expression.
* @param {ASTNode} node The callback node
* @param {ASTNode} parentNode The expression node
* @returns {boolean} Whether or not this is part of a callback expression
*/
function isCallbackExpression(node, parentNode) {
// ensure the parent node exists and is an expression
if (!parentNode || parentNode.type !== "ExpressionStatement") {
return false
}
// cb()
if (parentNode.expression === node) {
return true
}
// special case for cb && cb() and similar
if (
parentNode.expression.type === "BinaryExpression" ||
parentNode.expression.type === "LogicalExpression"
) {
if (parentNode.expression.right === node) {
return true
}
}
return false
}
return {
CallExpression(node) {
// if we're not a callback we can return
if (!isCallback(node)) {
return
}
// find the closest block, return or loop
const closestBlock =
findClosestParentOfType(node, [
"BlockStatement",
"ReturnStatement",
"ArrowFunctionExpression",
]) || {}
// if our parent is a return we know we're ok
if (closestBlock.type === "ReturnStatement") {
return
}
// arrow functions don't always have blocks and implicitly return
if (closestBlock.type === "ArrowFunctionExpression") {
return
}
// block statements are part of functions and most if statements
if (closestBlock.type === "BlockStatement") {
// find the last item in the block
const lastItem =
closestBlock.body[closestBlock.body.length - 1]
// if the callback is the last thing in a block that might be ok
if (isCallbackExpression(node, lastItem)) {
const parentType = closestBlock.parent.type
// but only if the block is part of a function
if (
parentType === "FunctionExpression" ||
parentType === "FunctionDeclaration" ||
parentType === "ArrowFunctionExpression"
) {
return
}
}
// ending a block with a return is also ok
if (lastItem.type === "ReturnStatement") {
// but only if the callback is immediately before
if (
isCallbackExpression(
node,
closestBlock.body[closestBlock.body.length - 2]
)
) {
return
}
}
}
// as long as you're the child of a function at this point you should be asked to return
if (
findClosestParentOfType(node, [
"FunctionDeclaration",
"FunctionExpression",
"ArrowFunctionExpression",
])
) {
context.report({ node, messageId: "missingReturn" })
}
},
}
},
}
|
