1 | /**
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2 | * @fileoverview A rule to set the maximum number of line of code in a function.
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3 | * @author Pete Ward <peteward44@gmail.com>
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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 | // Requirements
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9 | //------------------------------------------------------------------------------
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10 |
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11 | const astUtils = require("./utils/ast-utils");
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12 |
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13 | const lodash = require("lodash");
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14 |
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15 | //------------------------------------------------------------------------------
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16 | // Constants
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17 | //------------------------------------------------------------------------------
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18 |
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19 | const OPTIONS_SCHEMA = {
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20 | type: "object",
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21 | properties: {
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22 | max: {
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23 | type: "integer",
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24 | minimum: 0
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25 | },
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26 | skipComments: {
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27 | type: "boolean"
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28 | },
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29 | skipBlankLines: {
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30 | type: "boolean"
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31 | },
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32 | IIFEs: {
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33 | type: "boolean"
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34 | }
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35 | },
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36 | additionalProperties: false
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37 | };
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38 |
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39 | const OPTIONS_OR_INTEGER_SCHEMA = {
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40 | oneOf: [
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41 | OPTIONS_SCHEMA,
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42 | {
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43 | type: "integer",
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44 | minimum: 1
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45 | }
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46 | ]
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47 | };
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48 |
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49 | /**
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50 | * Given a list of comment nodes, return a map with numeric keys (source code line numbers) and comment token values.
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51 | * @param {Array} comments An array of comment nodes.
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52 | * @returns {Map.<string,Node>} A map with numeric keys (source code line numbers) and comment token values.
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53 | */
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54 | function getCommentLineNumbers(comments) {
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55 | const map = new Map();
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56 |
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57 | if (!comments) {
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58 | return map;
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59 | }
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60 | comments.forEach(comment => {
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61 | for (let i = comment.loc.start.line; i <= comment.loc.end.line; i++) {
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62 | map.set(i, comment);
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63 | }
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64 | });
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65 | return map;
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66 | }
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67 |
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68 | //------------------------------------------------------------------------------
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69 | // Rule Definition
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70 | //------------------------------------------------------------------------------
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71 |
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72 | module.exports = {
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73 | meta: {
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74 | type: "suggestion",
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75 |
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76 | docs: {
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77 | description: "enforce a maximum number of line of code in a function",
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78 | category: "Stylistic Issues",
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79 | recommended: false,
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80 | url: "https://eslint.org/docs/rules/max-lines-per-function"
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81 | },
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82 |
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83 | schema: [
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84 | OPTIONS_OR_INTEGER_SCHEMA
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85 | ],
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86 | messages: {
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87 | exceed: "{{name}} has too many lines ({{lineCount}}). Maximum allowed is {{maxLines}}."
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88 | }
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89 | },
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90 |
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91 | create(context) {
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92 | const sourceCode = context.getSourceCode();
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93 | const lines = sourceCode.lines;
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94 |
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95 | const option = context.options[0];
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96 | let maxLines = 50;
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97 | let skipComments = false;
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98 | let skipBlankLines = false;
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99 | let IIFEs = false;
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100 |
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101 | if (typeof option === "object") {
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102 | maxLines = typeof option.max === "number" ? option.max : 50;
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103 | skipComments = !!option.skipComments;
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104 | skipBlankLines = !!option.skipBlankLines;
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105 | IIFEs = !!option.IIFEs;
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106 | } else if (typeof option === "number") {
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107 | maxLines = option;
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108 | }
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109 |
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110 | const commentLineNumbers = getCommentLineNumbers(sourceCode.getAllComments());
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111 |
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112 | //--------------------------------------------------------------------------
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113 | // Helpers
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114 | //--------------------------------------------------------------------------
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115 |
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116 | /**
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117 | * Tells if a comment encompasses the entire line.
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118 | * @param {string} line The source line with a trailing comment
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119 | * @param {number} lineNumber The one-indexed line number this is on
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120 | * @param {ASTNode} comment The comment to remove
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121 | * @returns {boolean} If the comment covers the entire line
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122 | */
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123 | function isFullLineComment(line, lineNumber, comment) {
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124 | const start = comment.loc.start,
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125 | end = comment.loc.end,
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126 | isFirstTokenOnLine = start.line === lineNumber && !line.slice(0, start.column).trim(),
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127 | isLastTokenOnLine = end.line === lineNumber && !line.slice(end.column).trim();
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128 |
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129 | return comment &&
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130 | (start.line < lineNumber || isFirstTokenOnLine) &&
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131 | (end.line > lineNumber || isLastTokenOnLine);
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132 | }
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133 |
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134 | /**
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135 | * Identifies is a node is a FunctionExpression which is part of an IIFE
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136 | * @param {ASTNode} node Node to test
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137 | * @returns {boolean} True if it's an IIFE
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138 | */
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139 | function isIIFE(node) {
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140 | return node.type === "FunctionExpression" && node.parent && node.parent.type === "CallExpression" && node.parent.callee === node;
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141 | }
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142 |
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143 | /**
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144 | * Identifies is a node is a FunctionExpression which is embedded within a MethodDefinition or Property
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145 | * @param {ASTNode} node Node to test
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146 | * @returns {boolean} True if it's a FunctionExpression embedded within a MethodDefinition or Property
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147 | */
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148 | function isEmbedded(node) {
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149 | if (!node.parent) {
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150 | return false;
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151 | }
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152 | if (node !== node.parent.value) {
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153 | return false;
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154 | }
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155 | if (node.parent.type === "MethodDefinition") {
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156 | return true;
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157 | }
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158 | if (node.parent.type === "Property") {
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159 | return node.parent.method === true || node.parent.kind === "get" || node.parent.kind === "set";
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160 | }
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161 | return false;
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162 | }
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163 |
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164 | /**
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165 | * Count the lines in the function
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166 | * @param {ASTNode} funcNode Function AST node
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167 | * @returns {void}
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168 | * @private
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169 | */
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170 | function processFunction(funcNode) {
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171 | const node = isEmbedded(funcNode) ? funcNode.parent : funcNode;
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172 |
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173 | if (!IIFEs && isIIFE(node)) {
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174 | return;
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175 | }
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176 | let lineCount = 0;
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177 |
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178 | for (let i = node.loc.start.line - 1; i < node.loc.end.line; ++i) {
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179 | const line = lines[i];
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180 |
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181 | if (skipComments) {
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182 | if (commentLineNumbers.has(i + 1) && isFullLineComment(line, i + 1, commentLineNumbers.get(i + 1))) {
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183 | continue;
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184 | }
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185 | }
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186 |
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187 | if (skipBlankLines) {
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188 | if (line.match(/^\s*$/u)) {
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189 | continue;
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190 | }
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191 | }
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192 |
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193 | lineCount++;
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194 | }
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195 |
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196 | if (lineCount > maxLines) {
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197 | const name = lodash.upperFirst(astUtils.getFunctionNameWithKind(funcNode));
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198 |
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199 | context.report({
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200 | node,
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201 | messageId: "exceed",
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202 | data: { name, lineCount, maxLines }
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203 | });
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204 | }
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205 | }
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206 |
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207 | //--------------------------------------------------------------------------
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208 | // Public API
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209 | //--------------------------------------------------------------------------
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210 |
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211 | return {
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212 | FunctionDeclaration: processFunction,
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213 | FunctionExpression: processFunction,
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214 | ArrowFunctionExpression: processFunction
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215 | };
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216 | }
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217 | };
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