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home/ags/node_modules/eslint-plugin-n/lib/rules/no-callback-literal.js

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+/**
+ * @author Jamund Ferguson
+ * See LICENSE file in root directory for full license.
+ */
+"use strict"
+
+module.exports = {
+    meta: {
+        docs: {
+            description:
+                "enforce Node.js-style error-first callback pattern is followed",
+            recommended: false,
+            url: "https://github.com/eslint-community/eslint-plugin-n/blob/HEAD/docs/rules/no-callback-literal.md",
+        },
+        type: "problem",
+        fixable: null,
+        schema: [],
+        messages: {
+            unexpectedLiteral:
+                "Unexpected literal in error position of callback.",
+        },
+    },
+
+    create(context) {
+        const callbackNames = ["callback", "cb"]
+
+        function isCallback(name) {
+            return callbackNames.indexOf(name) > -1
+        }
+
+        return {
+            CallExpression(node) {
+                const errorArg = node.arguments[0]
+                const calleeName = node.callee.name
+
+                if (
+                    errorArg &&
+                    !couldBeError(errorArg) &&
+                    isCallback(calleeName)
+                ) {
+                    context.report({
+                        node,
+                        messageId: "unexpectedLiteral",
+                    })
+                }
+            },
+        }
+    },
+}
+
+/**
+ * Determine if a node has a possiblity to be an Error object
+ * @param  {ASTNode}  node  ASTNode to check
+ * @returns {boolean}       True if there is a chance it contains an Error obj
+ */
+function couldBeError(node) {
+    switch (node.type) {
+        case "Identifier":
+        case "CallExpression":
+        case "NewExpression":
+        case "MemberExpression":
+        case "TaggedTemplateExpression":
+        case "YieldExpression":
+            return true // possibly an error object.
+        case "Literal":
+            return node.value == null
+        case "AssignmentExpression":
+            return couldBeError(node.right)
+
+        case "SequenceExpression": {
+            const exprs = node.expressions
+            return exprs.length !== 0 && couldBeError(exprs[exprs.length - 1])
+        }
+
+        case "LogicalExpression":
+            return couldBeError(node.left) || couldBeError(node.right)
+
+        case "ConditionalExpression":
+            return couldBeError(node.consequent) || couldBeError(node.alternate)
+        default:
+            return true // assuming unknown nodes can be error objects.
+    }
+}