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qwen/nodejs/node_modules/eslint/lib/rules/no-await-in-loop.js

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+/**
+ * @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;
+    }
+}
+
+/** @type {import('../shared/types').Rule} */
+module.exports = {
+    meta: {
+        type: "problem",
+
+        docs: {
+            description: "Disallow `await` inside of loops",
+            recommended: false,
+            url: "https://eslint.org/docs/latest/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
+        };
+    }
+};