no-unsafe-finally.js
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/**
* @fileoverview Rule to flag unsafe statements in finally block
* @author Onur Temizkan
*/
"use strict";
//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------
const SENTINEL_NODE_TYPE_RETURN_THROW = /^(?:Program|(?:Function|Class)(?:Declaration|Expression)|ArrowFunctionExpression)$/u;
const SENTINEL_NODE_TYPE_BREAK = /^(?:Program|(?:Function|Class)(?:Declaration|Expression)|ArrowFunctionExpression|DoWhileStatement|WhileStatement|ForOfStatement|ForInStatement|ForStatement|SwitchStatement)$/u;
const SENTINEL_NODE_TYPE_CONTINUE = /^(?:Program|(?:Function|Class)(?:Declaration|Expression)|ArrowFunctionExpression|DoWhileStatement|WhileStatement|ForOfStatement|ForInStatement|ForStatement)$/u;
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
module.exports = {
meta: {
type: "problem",
docs: {
description: "disallow control flow statements in `finally` blocks",
category: "Possible Errors",
recommended: true,
url: "https://eslint.org/docs/rules/no-unsafe-finally"
},
schema: [],
messages: {
unsafeUsage: "Unsafe usage of {{nodeType}}."
}
},
create(context) {
/**
* Checks if the node is the finalizer of a TryStatement
* @param {ASTNode} node node to check.
* @returns {boolean} - true if the node is the finalizer of a TryStatement
*/
function isFinallyBlock(node) {
return node.parent.type === "TryStatement" && node.parent.finalizer === node;
}
/**
* Climbs up the tree if the node is not a sentinel node
* @param {ASTNode} node node to check.
* @param {string} label label of the break or continue statement
* @returns {boolean} - return whether the node is a finally block or a sentinel node
*/
function isInFinallyBlock(node, label) {
let labelInside = false;
let sentinelNodeType;
if (node.type === "BreakStatement" && !node.label) {
sentinelNodeType = SENTINEL_NODE_TYPE_BREAK;
} else if (node.type === "ContinueStatement") {
sentinelNodeType = SENTINEL_NODE_TYPE_CONTINUE;
} else {
sentinelNodeType = SENTINEL_NODE_TYPE_RETURN_THROW;
}
for (
let currentNode = node;
currentNode && !sentinelNodeType.test(currentNode.type);
currentNode = currentNode.parent
) {
if (currentNode.parent.label && label && (currentNode.parent.label.name === label.name)) {
labelInside = true;
}
if (isFinallyBlock(currentNode)) {
if (label && labelInside) {
return false;
}
return true;
}
}
return false;
}
/**
* Checks whether the possibly-unsafe statement is inside a finally block.
* @param {ASTNode} node node to check.
* @returns {void}
*/
function check(node) {
if (isInFinallyBlock(node, node.label)) {
context.report({
messageId: "unsafeUsage",
data: {
nodeType: node.type
},
node,
line: node.loc.line,
column: node.loc.column
});
}
}
return {
ReturnStatement: check,
ThrowStatement: check,
BreakStatement: check,
ContinueStatement: check
};
}
};