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