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1/**
2 * @fileoverview Rule to enforce a maximum number of nested callbacks.
3 * @author Ian Christian Myers
4 */
5
6"use strict";
7
8//------------------------------------------------------------------------------
9// Rule Definition
10//------------------------------------------------------------------------------
11
12module.exports = {
13    meta: {
14        type: "suggestion",
15
16        docs: {
17            description: "enforce a maximum depth that callbacks can be nested",
18            category: "Stylistic Issues",
19            recommended: false,
20            url: "https://eslint.org/docs/rules/max-nested-callbacks"
21        },
22
23        schema: [
24            {
25                oneOf: [
26                    {
27                        type: "integer",
28                        minimum: 0
29                    },
30                    {
31                        type: "object",
32                        properties: {
33                            maximum: {
34                                type: "integer",
35                                minimum: 0
36                            },
37                            max: {
38                                type: "integer",
39                                minimum: 0
40                            }
41                        },
42                        additionalProperties: false
43                    }
44                ]
45            }
46        ],
47        messages: {
48            exceed: "Too many nested callbacks ({{num}}). Maximum allowed is {{max}}."
49        }
50    },
51
52    create(context) {
53
54        //--------------------------------------------------------------------------
55        // Constants
56        //--------------------------------------------------------------------------
57        const option = context.options[0];
58        let THRESHOLD = 10;
59
60        if (
61            typeof option === "object" &&
62            (Object.prototype.hasOwnProperty.call(option, "maximum") || Object.prototype.hasOwnProperty.call(option, "max"))
63        ) {
64            THRESHOLD = option.maximum || option.max;
65        } else if (typeof option === "number") {
66            THRESHOLD = option;
67        }
68
69        //--------------------------------------------------------------------------
70        // Helpers
71        //--------------------------------------------------------------------------
72
73        const callbackStack = [];
74
75        /**
76         * Checks a given function node for too many callbacks.
77         * @param {ASTNode} node The node to check.
78         * @returns {void}
79         * @private
80         */
81        function checkFunction(node) {
82            const parent = node.parent;
83
84            if (parent.type === "CallExpression") {
85                callbackStack.push(node);
86            }
87
88            if (callbackStack.length > THRESHOLD) {
89                const opts = { num: callbackStack.length, max: THRESHOLD };
90
91                context.report({ node, messageId: "exceed", data: opts });
92            }
93        }
94
95        /**
96         * Pops the call stack.
97         * @returns {void}
98         * @private
99         */
100        function popStack() {
101            callbackStack.pop();
102        }
103
104        //--------------------------------------------------------------------------
105        // Public API
106        //--------------------------------------------------------------------------
107
108        return {
109            ArrowFunctionExpression: checkFunction,
110            "ArrowFunctionExpression:exit": popStack,
111
112            FunctionExpression: checkFunction,
113            "FunctionExpression:exit": popStack
114        };
115
116    }
117};
118