1 | /**
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2 | * @fileoverview Comma style - enforces comma styles of two types: last and first
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3 | * @author Vignesh Anand aka vegetableman
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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 | const astUtils = require("../ast-utils");
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9 |
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10 | //------------------------------------------------------------------------------
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11 | // Rule Definition
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12 | //------------------------------------------------------------------------------
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13 |
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14 | module.exports = {
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15 | meta: {
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16 | docs: {
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17 | description: "enforce consistent comma style",
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18 | category: "Stylistic Issues",
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19 | recommended: false,
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20 | url: "https://eslint.org/docs/rules/comma-style"
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21 | },
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22 | fixable: "code",
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23 | schema: [
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24 | {
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25 | enum: ["first", "last"]
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26 | },
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27 | {
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28 | type: "object",
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29 | properties: {
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30 | exceptions: {
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31 | type: "object",
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32 | additionalProperties: {
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33 | type: "boolean"
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34 | }
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35 | }
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36 | },
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37 | additionalProperties: false
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38 | }
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39 | ],
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40 | messages: {
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41 | unexpectedLineBeforeAndAfterComma: "Bad line breaking before and after ','.",
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42 | expectedCommaFirst: "',' should be placed first.",
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43 | expectedCommaLast: "',' should be placed last."
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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 | const style = context.options[0] || "last",
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49 | sourceCode = context.getSourceCode();
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50 | const exceptions = {
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51 | ArrayPattern: true,
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52 | ArrowFunctionExpression: true,
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53 | CallExpression: true,
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54 | FunctionDeclaration: true,
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55 | FunctionExpression: true,
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56 | ImportDeclaration: true,
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57 | ObjectPattern: true,
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58 | NewExpression: true
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59 | };
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60 |
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61 | if (context.options.length === 2 && context.options[1].hasOwnProperty("exceptions")) {
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62 | const keys = Object.keys(context.options[1].exceptions);
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63 |
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64 | for (let i = 0; i < keys.length; i++) {
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65 | exceptions[keys[i]] = context.options[1].exceptions[keys[i]];
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66 | }
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67 | }
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68 |
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69 | //--------------------------------------------------------------------------
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70 | // Helpers
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71 | //--------------------------------------------------------------------------
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72 |
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73 | /**
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74 | * Modified text based on the style
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75 | * @param {string} styleType Style type
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76 | * @param {string} text Source code text
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77 | * @returns {string} modified text
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78 | * @private
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79 | */
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80 | function getReplacedText(styleType, text) {
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81 | switch (styleType) {
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82 | case "between":
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83 | return `,${text.replace("\n", "")}`;
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84 |
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85 | case "first":
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86 | return `${text},`;
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87 |
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88 | case "last":
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89 | return `,${text}`;
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90 |
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91 | default:
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92 | return "";
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93 | }
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94 | }
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95 |
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96 | /**
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97 | * Determines the fixer function for a given style.
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98 | * @param {string} styleType comma style
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99 | * @param {ASTNode} previousItemToken The token to check.
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100 | * @param {ASTNode} commaToken The token to check.
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101 | * @param {ASTNode} currentItemToken The token to check.
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102 | * @returns {Function} Fixer function
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103 | * @private
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104 | */
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105 | function getFixerFunction(styleType, previousItemToken, commaToken, currentItemToken) {
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106 | const text =
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107 | sourceCode.text.slice(previousItemToken.range[1], commaToken.range[0]) +
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108 | sourceCode.text.slice(commaToken.range[1], currentItemToken.range[0]);
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109 | const range = [previousItemToken.range[1], currentItemToken.range[0]];
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110 |
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111 | return function(fixer) {
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112 | return fixer.replaceTextRange(range, getReplacedText(styleType, text));
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113 | };
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114 | }
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115 |
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116 | /**
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117 | * Validates the spacing around single items in lists.
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118 | * @param {Token} previousItemToken The last token from the previous item.
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119 | * @param {Token} commaToken The token representing the comma.
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120 | * @param {Token} currentItemToken The first token of the current item.
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121 | * @param {Token} reportItem The item to use when reporting an error.
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122 | * @returns {void}
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123 | * @private
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124 | */
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125 | function validateCommaItemSpacing(previousItemToken, commaToken, currentItemToken, reportItem) {
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126 |
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127 | // if single line
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128 | if (astUtils.isTokenOnSameLine(commaToken, currentItemToken) &&
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129 | astUtils.isTokenOnSameLine(previousItemToken, commaToken)) {
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130 |
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131 | // do nothing.
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132 |
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133 | } else if (!astUtils.isTokenOnSameLine(commaToken, currentItemToken) &&
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134 | !astUtils.isTokenOnSameLine(previousItemToken, commaToken)) {
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135 |
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136 | // lone comma
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137 | context.report({
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138 | node: reportItem,
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139 | loc: {
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140 | line: commaToken.loc.end.line,
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141 | column: commaToken.loc.start.column
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142 | },
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143 | messageId: "unexpectedLineBeforeAndAfterComma",
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144 | fix: getFixerFunction("between", previousItemToken, commaToken, currentItemToken)
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145 | });
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146 |
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147 | } else if (style === "first" && !astUtils.isTokenOnSameLine(commaToken, currentItemToken)) {
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148 |
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149 | context.report({
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150 | node: reportItem,
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151 | messageId: "expectedCommaFirst",
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152 | fix: getFixerFunction(style, previousItemToken, commaToken, currentItemToken)
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153 | });
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154 |
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155 | } else if (style === "last" && astUtils.isTokenOnSameLine(commaToken, currentItemToken)) {
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156 |
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157 | context.report({
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158 | node: reportItem,
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159 | loc: {
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160 | line: commaToken.loc.end.line,
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161 | column: commaToken.loc.end.column
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162 | },
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163 | messageId: "expectedCommaLast",
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164 | fix: getFixerFunction(style, previousItemToken, commaToken, currentItemToken)
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165 | });
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166 | }
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167 | }
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168 |
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169 | /**
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170 | * Checks the comma placement with regards to a declaration/property/element
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171 | * @param {ASTNode} node The binary expression node to check
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172 | * @param {string} property The property of the node containing child nodes.
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173 | * @private
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174 | * @returns {void}
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175 | */
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176 | function validateComma(node, property) {
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177 | const items = node[property],
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178 | arrayLiteral = (node.type === "ArrayExpression" || node.type === "ArrayPattern");
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179 |
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180 | if (items.length > 1 || arrayLiteral) {
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181 |
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182 | // seed as opening [
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183 | let previousItemToken = sourceCode.getFirstToken(node);
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184 |
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185 | items.forEach(item => {
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186 | const commaToken = item ? sourceCode.getTokenBefore(item) : previousItemToken,
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187 | currentItemToken = item ? sourceCode.getFirstToken(item) : sourceCode.getTokenAfter(commaToken),
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188 | reportItem = item || currentItemToken,
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189 | tokenBeforeComma = sourceCode.getTokenBefore(commaToken);
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190 |
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191 | // Check if previous token is wrapped in parentheses
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192 | if (tokenBeforeComma && astUtils.isClosingParenToken(tokenBeforeComma)) {
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193 | previousItemToken = tokenBeforeComma;
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194 | }
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195 |
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196 | /*
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197 | * This works by comparing three token locations:
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198 | * - previousItemToken is the last token of the previous item
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199 | * - commaToken is the location of the comma before the current item
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200 | * - currentItemToken is the first token of the current item
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201 | *
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202 | * These values get switched around if item is undefined.
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203 | * previousItemToken will refer to the last token not belonging
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204 | * to the current item, which could be a comma or an opening
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205 | * square bracket. currentItemToken could be a comma.
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206 | *
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207 | * All comparisons are done based on these tokens directly, so
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208 | * they are always valid regardless of an undefined item.
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209 | */
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210 | if (astUtils.isCommaToken(commaToken)) {
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211 | validateCommaItemSpacing(previousItemToken, commaToken,
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212 | currentItemToken, reportItem);
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213 | }
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214 |
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215 | if (item) {
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216 | const tokenAfterItem = sourceCode.getTokenAfter(item, astUtils.isNotClosingParenToken);
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217 |
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218 | previousItemToken = tokenAfterItem
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219 | ? sourceCode.getTokenBefore(tokenAfterItem)
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220 | : sourceCode.ast.tokens[sourceCode.ast.tokens.length - 1];
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221 | }
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222 | });
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223 |
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224 | /*
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225 | * Special case for array literals that have empty last items, such
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226 | * as [ 1, 2, ]. These arrays only have two items show up in the
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227 | * AST, so we need to look at the token to verify that there's no
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228 | * dangling comma.
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229 | */
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230 | if (arrayLiteral) {
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231 |
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232 | const lastToken = sourceCode.getLastToken(node),
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233 | nextToLastToken = sourceCode.getTokenBefore(lastToken);
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234 |
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235 | if (astUtils.isCommaToken(nextToLastToken)) {
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236 | validateCommaItemSpacing(
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237 | sourceCode.getTokenBefore(nextToLastToken),
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238 | nextToLastToken,
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239 | lastToken,
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240 | lastToken
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241 | );
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242 | }
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243 | }
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244 | }
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245 | }
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246 |
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247 | //--------------------------------------------------------------------------
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248 | // Public
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249 | //--------------------------------------------------------------------------
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250 |
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251 | const nodes = {};
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252 |
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253 | if (!exceptions.VariableDeclaration) {
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254 | nodes.VariableDeclaration = function(node) {
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255 | validateComma(node, "declarations");
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256 | };
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257 | }
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258 | if (!exceptions.ObjectExpression) {
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259 | nodes.ObjectExpression = function(node) {
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260 | validateComma(node, "properties");
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261 | };
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262 | }
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263 | if (!exceptions.ObjectPattern) {
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264 | nodes.ObjectPattern = function(node) {
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265 | validateComma(node, "properties");
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266 | };
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267 | }
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268 | if (!exceptions.ArrayExpression) {
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269 | nodes.ArrayExpression = function(node) {
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270 | validateComma(node, "elements");
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271 | };
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272 | }
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273 | if (!exceptions.ArrayPattern) {
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274 | nodes.ArrayPattern = function(node) {
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275 | validateComma(node, "elements");
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276 | };
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277 | }
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278 | if (!exceptions.FunctionDeclaration) {
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279 | nodes.FunctionDeclaration = function(node) {
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280 | validateComma(node, "params");
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281 | };
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282 | }
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283 | if (!exceptions.FunctionExpression) {
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284 | nodes.FunctionExpression = function(node) {
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285 | validateComma(node, "params");
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286 | };
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287 | }
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288 | if (!exceptions.ArrowFunctionExpression) {
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289 | nodes.ArrowFunctionExpression = function(node) {
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290 | validateComma(node, "params");
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291 | };
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292 | }
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293 | if (!exceptions.CallExpression) {
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294 | nodes.CallExpression = function(node) {
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295 | validateComma(node, "arguments");
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296 | };
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297 | }
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298 | if (!exceptions.ImportDeclaration) {
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299 | nodes.ImportDeclaration = function(node) {
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300 | validateComma(node, "specifiers");
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301 | };
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302 | }
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303 | if (!exceptions.NewExpression) {
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304 | nodes.NewExpression = function(node) {
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305 | validateComma(node, "arguments");
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306 | };
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307 | }
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308 |
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309 | return nodes;
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310 | }
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311 | };
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