1 | /**
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2 | * @fileoverview Rule to check for max length on a line.
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3 | * @author Matt DuVall <http://www.mattduvall.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 | //------------------------------------------------------------------------------
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9 | // Constants
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10 | //------------------------------------------------------------------------------
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11 |
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12 | const OPTIONS_SCHEMA = {
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13 | type: "object",
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14 | properties: {
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15 | code: {
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16 | type: "integer",
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17 | minimum: 0
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18 | },
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19 | comments: {
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20 | type: "integer",
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21 | minimum: 0
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22 | },
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23 | tabWidth: {
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24 | type: "integer",
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25 | minimum: 0
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26 | },
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27 | ignorePattern: {
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28 | type: "string"
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29 | },
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30 | ignoreComments: {
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31 | type: "boolean"
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32 | },
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33 | ignoreStrings: {
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34 | type: "boolean"
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35 | },
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36 | ignoreUrls: {
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37 | type: "boolean"
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38 | },
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39 | ignoreTemplateLiterals: {
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40 | type: "boolean"
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41 | },
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42 | ignoreRegExpLiterals: {
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43 | type: "boolean"
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44 | },
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45 | ignoreTrailingComments: {
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46 | type: "boolean"
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47 | }
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48 | },
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49 | additionalProperties: false
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50 | };
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51 |
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52 | const OPTIONS_OR_INTEGER_SCHEMA = {
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53 | anyOf: [
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54 | OPTIONS_SCHEMA,
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55 | {
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56 | type: "integer",
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57 | minimum: 0
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58 | }
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59 | ]
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60 | };
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61 |
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62 | //------------------------------------------------------------------------------
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63 | // Rule Definition
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64 | //------------------------------------------------------------------------------
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65 |
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66 | module.exports = {
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67 | meta: {
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68 | docs: {
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69 | description: "enforce a maximum line length",
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70 | category: "Stylistic Issues",
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71 | recommended: false,
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72 | url: "https://eslint.org/docs/rules/max-len"
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73 | },
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74 |
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75 | schema: [
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76 | OPTIONS_OR_INTEGER_SCHEMA,
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77 | OPTIONS_OR_INTEGER_SCHEMA,
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78 | OPTIONS_SCHEMA
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79 | ]
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80 | },
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81 |
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82 | create(context) {
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83 |
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84 | /*
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85 | * Inspired by http://tools.ietf.org/html/rfc3986#appendix-B, however:
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86 | * - They're matching an entire string that we know is a URI
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87 | * - We're matching part of a string where we think there *might* be a URL
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88 | * - We're only concerned about URLs, as picking out any URI would cause
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89 | * too many false positives
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90 | * - We don't care about matching the entire URL, any small segment is fine
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91 | */
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92 | const URL_REGEXP = /[^:/?#]:\/\/[^?#]/;
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93 |
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94 | const sourceCode = context.getSourceCode();
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95 |
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96 | /**
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97 | * Computes the length of a line that may contain tabs. The width of each
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98 | * tab will be the number of spaces to the next tab stop.
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99 | * @param {string} line The line.
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100 | * @param {int} tabWidth The width of each tab stop in spaces.
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101 | * @returns {int} The computed line length.
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102 | * @private
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103 | */
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104 | function computeLineLength(line, tabWidth) {
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105 | let extraCharacterCount = 0;
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106 |
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107 | line.replace(/\t/g, (match, offset) => {
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108 | const totalOffset = offset + extraCharacterCount,
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109 | previousTabStopOffset = tabWidth ? totalOffset % tabWidth : 0,
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110 | spaceCount = tabWidth - previousTabStopOffset;
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111 |
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112 | extraCharacterCount += spaceCount - 1; // -1 for the replaced tab
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113 | });
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114 | return Array.from(line).length + extraCharacterCount;
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115 | }
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116 |
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117 | // The options object must be the last option specified…
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118 | const lastOption = context.options[context.options.length - 1];
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119 | const options = typeof lastOption === "object" ? Object.create(lastOption) : {};
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120 |
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121 | // …but max code length…
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122 | if (typeof context.options[0] === "number") {
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123 | options.code = context.options[0];
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124 | }
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125 |
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126 | // …and tabWidth can be optionally specified directly as integers.
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127 | if (typeof context.options[1] === "number") {
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128 | options.tabWidth = context.options[1];
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129 | }
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130 |
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131 | const maxLength = options.code || 80,
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132 | tabWidth = options.tabWidth || 4,
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133 | ignoreComments = options.ignoreComments || false,
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134 | ignoreStrings = options.ignoreStrings || false,
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135 | ignoreTemplateLiterals = options.ignoreTemplateLiterals || false,
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136 | ignoreRegExpLiterals = options.ignoreRegExpLiterals || false,
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137 | ignoreTrailingComments = options.ignoreTrailingComments || options.ignoreComments || false,
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138 | ignoreUrls = options.ignoreUrls || false,
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139 | maxCommentLength = options.comments;
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140 | let ignorePattern = options.ignorePattern || null;
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141 |
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142 | if (ignorePattern) {
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143 | ignorePattern = new RegExp(ignorePattern);
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144 | }
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145 |
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146 | //--------------------------------------------------------------------------
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147 | // Helpers
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148 | //--------------------------------------------------------------------------
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149 |
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150 | /**
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151 | * Tells if a given comment is trailing: it starts on the current line and
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152 | * extends to or past the end of the current line.
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153 | * @param {string} line The source line we want to check for a trailing comment on
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154 | * @param {number} lineNumber The one-indexed line number for line
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155 | * @param {ASTNode} comment The comment to inspect
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156 | * @returns {boolean} If the comment is trailing on the given line
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157 | */
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158 | function isTrailingComment(line, lineNumber, comment) {
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159 | return comment &&
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160 | (comment.loc.start.line === lineNumber && lineNumber <= comment.loc.end.line) &&
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161 | (comment.loc.end.line > lineNumber || comment.loc.end.column === line.length);
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162 | }
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163 |
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164 | /**
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165 | * Tells if a comment encompasses the entire line.
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166 | * @param {string} line The source line with a trailing comment
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167 | * @param {number} lineNumber The one-indexed line number this is on
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168 | * @param {ASTNode} comment The comment to remove
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169 | * @returns {boolean} If the comment covers the entire line
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170 | */
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171 | function isFullLineComment(line, lineNumber, comment) {
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172 | const start = comment.loc.start,
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173 | end = comment.loc.end,
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174 | isFirstTokenOnLine = !line.slice(0, comment.loc.start.column).trim();
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175 |
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176 | return comment &&
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177 | (start.line < lineNumber || (start.line === lineNumber && isFirstTokenOnLine)) &&
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178 | (end.line > lineNumber || (end.line === lineNumber && end.column === line.length));
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179 | }
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180 |
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181 | /**
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182 | * Gets the line after the comment and any remaining trailing whitespace is
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183 | * stripped.
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184 | * @param {string} line The source line with a trailing comment
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185 | * @param {ASTNode} comment The comment to remove
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186 | * @returns {string} Line without comment and trailing whitepace
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187 | */
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188 | function stripTrailingComment(line, comment) {
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189 |
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190 | // loc.column is zero-indexed
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191 | return line.slice(0, comment.loc.start.column).replace(/\s+$/, "");
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192 | }
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193 |
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194 | /**
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195 | * Ensure that an array exists at [key] on `object`, and add `value` to it.
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196 | *
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197 | * @param {Object} object the object to mutate
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198 | * @param {string} key the object's key
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199 | * @param {*} value the value to add
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200 | * @returns {void}
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201 | * @private
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202 | */
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203 | function ensureArrayAndPush(object, key, value) {
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204 | if (!Array.isArray(object[key])) {
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205 | object[key] = [];
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206 | }
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207 | object[key].push(value);
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208 | }
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209 |
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210 | /**
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211 | * Retrieves an array containing all strings (" or ') in the source code.
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212 | *
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213 | * @returns {ASTNode[]} An array of string nodes.
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214 | */
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215 | function getAllStrings() {
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216 | return sourceCode.ast.tokens.filter(token => (token.type === "String" ||
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217 | (token.type === "JSXText" && sourceCode.getNodeByRangeIndex(token.range[0] - 1).type === "JSXAttribute")));
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218 | }
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219 |
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220 | /**
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221 | * Retrieves an array containing all template literals in the source code.
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222 | *
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223 | * @returns {ASTNode[]} An array of template literal nodes.
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224 | */
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225 | function getAllTemplateLiterals() {
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226 | return sourceCode.ast.tokens.filter(token => token.type === "Template");
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227 | }
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228 |
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229 |
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230 | /**
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231 | * Retrieves an array containing all RegExp literals in the source code.
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232 | *
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233 | * @returns {ASTNode[]} An array of RegExp literal nodes.
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234 | */
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235 | function getAllRegExpLiterals() {
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236 | return sourceCode.ast.tokens.filter(token => token.type === "RegularExpression");
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237 | }
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238 |
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239 |
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240 | /**
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241 | * A reducer to group an AST node by line number, both start and end.
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242 | *
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243 | * @param {Object} acc the accumulator
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244 | * @param {ASTNode} node the AST node in question
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245 | * @returns {Object} the modified accumulator
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246 | * @private
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247 | */
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248 | function groupByLineNumber(acc, node) {
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249 | for (let i = node.loc.start.line; i <= node.loc.end.line; ++i) {
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250 | ensureArrayAndPush(acc, i, node);
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251 | }
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252 | return acc;
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253 | }
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254 |
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255 | /**
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256 | * Check the program for max length
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257 | * @param {ASTNode} node Node to examine
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258 | * @returns {void}
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259 | * @private
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260 | */
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261 | function checkProgramForMaxLength(node) {
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262 |
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263 | // split (honors line-ending)
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264 | const lines = sourceCode.lines,
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265 |
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266 | // list of comments to ignore
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267 | comments = ignoreComments || maxCommentLength || ignoreTrailingComments ? sourceCode.getAllComments() : [];
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268 |
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269 | // we iterate over comments in parallel with the lines
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270 | let commentsIndex = 0;
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271 |
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272 | const strings = getAllStrings();
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273 | const stringsByLine = strings.reduce(groupByLineNumber, {});
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274 |
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275 | const templateLiterals = getAllTemplateLiterals();
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276 | const templateLiteralsByLine = templateLiterals.reduce(groupByLineNumber, {});
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277 |
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278 | const regExpLiterals = getAllRegExpLiterals();
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279 | const regExpLiteralsByLine = regExpLiterals.reduce(groupByLineNumber, {});
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280 |
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281 | lines.forEach((line, i) => {
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282 |
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283 | // i is zero-indexed, line numbers are one-indexed
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284 | const lineNumber = i + 1;
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285 |
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286 | /*
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287 | * if we're checking comment length; we need to know whether this
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288 | * line is a comment
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289 | */
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290 | let lineIsComment = false;
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291 | let textToMeasure;
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292 |
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293 | /*
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294 | * We can short-circuit the comment checks if we're already out of
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295 | * comments to check.
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296 | */
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297 | if (commentsIndex < comments.length) {
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298 | let comment = null;
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299 |
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300 | // iterate over comments until we find one past the current line
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301 | do {
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302 | comment = comments[++commentsIndex];
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303 | } while (comment && comment.loc.start.line <= lineNumber);
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304 |
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305 | // and step back by one
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306 | comment = comments[--commentsIndex];
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307 |
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308 | if (isFullLineComment(line, lineNumber, comment)) {
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309 | lineIsComment = true;
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310 | textToMeasure = line;
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311 | } else if (ignoreTrailingComments && isTrailingComment(line, lineNumber, comment)) {
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312 | textToMeasure = stripTrailingComment(line, comment);
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313 | } else {
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314 | textToMeasure = line;
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315 | }
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316 | } else {
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317 | textToMeasure = line;
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318 | }
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319 | if (ignorePattern && ignorePattern.test(textToMeasure) ||
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320 | ignoreUrls && URL_REGEXP.test(textToMeasure) ||
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321 | ignoreStrings && stringsByLine[lineNumber] ||
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322 | ignoreTemplateLiterals && templateLiteralsByLine[lineNumber] ||
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323 | ignoreRegExpLiterals && regExpLiteralsByLine[lineNumber]
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324 | ) {
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325 |
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326 | // ignore this line
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327 | return;
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328 | }
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329 |
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330 | const lineLength = computeLineLength(textToMeasure, tabWidth);
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331 | const commentLengthApplies = lineIsComment && maxCommentLength;
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332 |
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333 | if (lineIsComment && ignoreComments) {
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334 | return;
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335 | }
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336 |
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337 | if (commentLengthApplies) {
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338 | if (lineLength > maxCommentLength) {
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339 | context.report({
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340 | node,
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341 | loc: { line: lineNumber, column: 0 },
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342 | message: "Line {{lineNumber}} exceeds the maximum comment line length of {{maxCommentLength}}.",
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343 | data: {
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344 | lineNumber: i + 1,
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345 | maxCommentLength
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346 | }
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347 | });
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348 | }
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349 | } else if (lineLength > maxLength) {
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350 | context.report({
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351 | node,
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352 | loc: { line: lineNumber, column: 0 },
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353 | message: "Line {{lineNumber}} exceeds the maximum line length of {{maxLength}}.",
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354 | data: {
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355 | lineNumber: i + 1,
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356 | maxLength
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357 | }
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358 | });
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359 | }
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360 | });
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361 | }
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362 |
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363 |
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364 | //--------------------------------------------------------------------------
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365 | // Public API
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366 | //--------------------------------------------------------------------------
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367 |
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368 | return {
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369 | Program: checkProgramForMaxLength
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370 | };
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371 |
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372 | }
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373 | };
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