103 lines
2.7 KiB
JavaScript
103 lines
2.7 KiB
JavaScript
/**
|
|
* @fileoverview Rule to disallow uses of await inside of loops.
|
|
* @author Nat Mote (nmote)
|
|
*/
|
|
"use strict";
|
|
|
|
/**
|
|
* Check whether it should stop traversing ancestors at the given node.
|
|
* @param {ASTNode} node A node to check.
|
|
* @returns {boolean} `true` if it should stop traversing.
|
|
*/
|
|
function isBoundary(node) {
|
|
const t = node.type;
|
|
|
|
return (
|
|
t === "FunctionDeclaration" ||
|
|
t === "FunctionExpression" ||
|
|
t === "ArrowFunctionExpression" ||
|
|
|
|
/*
|
|
* Don't report the await expressions on for-await-of loop since it's
|
|
* asynchronous iteration intentionally.
|
|
*/
|
|
(t === "ForOfStatement" && node.await === true)
|
|
);
|
|
}
|
|
|
|
/**
|
|
* Check whether the given node is in loop.
|
|
* @param {ASTNode} node A node to check.
|
|
* @param {ASTNode} parent A parent node to check.
|
|
* @returns {boolean} `true` if the node is in loop.
|
|
*/
|
|
function isLooped(node, parent) {
|
|
switch (parent.type) {
|
|
case "ForStatement":
|
|
return (
|
|
node === parent.test ||
|
|
node === parent.update ||
|
|
node === parent.body
|
|
);
|
|
|
|
case "ForOfStatement":
|
|
case "ForInStatement":
|
|
return node === parent.body;
|
|
|
|
case "WhileStatement":
|
|
case "DoWhileStatement":
|
|
return node === parent.test || node === parent.body;
|
|
|
|
default:
|
|
return false;
|
|
}
|
|
}
|
|
|
|
module.exports = {
|
|
meta: {
|
|
docs: {
|
|
description: "disallow `await` inside of loops",
|
|
category: "Possible Errors",
|
|
recommended: false,
|
|
url: "https://eslint.org/docs/rules/no-await-in-loop"
|
|
},
|
|
schema: [],
|
|
messages: {
|
|
unexpectedAwait: "Unexpected `await` inside a loop."
|
|
}
|
|
},
|
|
create(context) {
|
|
|
|
/**
|
|
* Validate an await expression.
|
|
* @param {ASTNode} awaitNode An AwaitExpression or ForOfStatement node to validate.
|
|
* @returns {void}
|
|
*/
|
|
function validate(awaitNode) {
|
|
if (awaitNode.type === "ForOfStatement" && !awaitNode.await) {
|
|
return;
|
|
}
|
|
|
|
let node = awaitNode;
|
|
let parent = node.parent;
|
|
|
|
while (parent && !isBoundary(parent)) {
|
|
if (isLooped(node, parent)) {
|
|
context.report({
|
|
node: awaitNode,
|
|
messageId: "unexpectedAwait"
|
|
});
|
|
return;
|
|
}
|
|
node = parent;
|
|
parent = parent.parent;
|
|
}
|
|
}
|
|
|
|
return {
|
|
AwaitExpression: validate,
|
|
ForOfStatement: validate
|
|
};
|
|
}
|
|
};
|