1 | /**
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2 | * @fileoverview Rule to disallow mixed binary operators.
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3 | * @author Toru Nagashima
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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 | // Requirements
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10 | //------------------------------------------------------------------------------
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11 |
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12 | const astUtils = require("./utils/ast-utils.js");
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13 |
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14 | //------------------------------------------------------------------------------
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15 | // Helpers
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16 | //------------------------------------------------------------------------------
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17 |
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18 | const ARITHMETIC_OPERATORS = ["+", "-", "*", "/", "%", "**"];
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19 | const BITWISE_OPERATORS = ["&", "|", "^", "~", "<<", ">>", ">>>"];
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20 | const COMPARISON_OPERATORS = ["==", "!=", "===", "!==", ">", ">=", "<", "<="];
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21 | const LOGICAL_OPERATORS = ["&&", "||"];
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22 | const RELATIONAL_OPERATORS = ["in", "instanceof"];
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23 | const TERNARY_OPERATOR = ["?:"];
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24 | const COALESCE_OPERATOR = ["??"];
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25 | const ALL_OPERATORS = [].concat(
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26 | ARITHMETIC_OPERATORS,
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27 | BITWISE_OPERATORS,
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28 | COMPARISON_OPERATORS,
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29 | LOGICAL_OPERATORS,
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30 | RELATIONAL_OPERATORS,
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31 | TERNARY_OPERATOR,
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32 | COALESCE_OPERATOR
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33 | );
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34 | const DEFAULT_GROUPS = [
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35 | ARITHMETIC_OPERATORS,
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36 | BITWISE_OPERATORS,
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37 | COMPARISON_OPERATORS,
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38 | LOGICAL_OPERATORS,
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39 | RELATIONAL_OPERATORS
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40 | ];
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41 | const TARGET_NODE_TYPE = /^(?:Binary|Logical|Conditional)Expression$/u;
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42 |
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43 | /**
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44 | * Normalizes options.
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45 | * @param {Object|undefined} options A options object to normalize.
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46 | * @returns {Object} Normalized option object.
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47 | */
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48 | function normalizeOptions(options = {}) {
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49 | const hasGroups = options.groups && options.groups.length > 0;
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50 | const groups = hasGroups ? options.groups : DEFAULT_GROUPS;
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51 | const allowSamePrecedence = options.allowSamePrecedence !== false;
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52 |
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53 | return {
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54 | groups,
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55 | allowSamePrecedence
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56 | };
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57 | }
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58 |
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59 | /**
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60 | * Checks whether any group which includes both given operator exists or not.
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61 | * @param {Array.<string[]>} groups A list of groups to check.
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62 | * @param {string} left An operator.
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63 | * @param {string} right Another operator.
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64 | * @returns {boolean} `true` if such group existed.
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65 | */
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66 | function includesBothInAGroup(groups, left, right) {
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67 | return groups.some(group => group.indexOf(left) !== -1 && group.indexOf(right) !== -1);
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68 | }
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69 |
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70 | /**
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71 | * Checks whether the given node is a conditional expression and returns the test node else the left node.
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72 | * @param {ASTNode} node A node which can be a BinaryExpression or a LogicalExpression node.
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73 | * This parent node can be BinaryExpression, LogicalExpression
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74 | * , or a ConditionalExpression node
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75 | * @returns {ASTNode} node the appropriate node(left or test).
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76 | */
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77 | function getChildNode(node) {
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78 | return node.type === "ConditionalExpression" ? node.test : node.left;
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79 | }
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80 |
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81 | //------------------------------------------------------------------------------
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82 | // Rule Definition
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83 | //------------------------------------------------------------------------------
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84 |
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85 | module.exports = {
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86 | meta: {
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87 | type: "suggestion",
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88 |
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89 | docs: {
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90 | description: "disallow mixed binary operators",
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91 | category: "Stylistic Issues",
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92 | recommended: false,
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93 | url: "https://eslint.org/docs/rules/no-mixed-operators"
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94 | },
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95 |
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96 | schema: [
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97 | {
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98 | type: "object",
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99 | properties: {
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100 | groups: {
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101 | type: "array",
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102 | items: {
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103 | type: "array",
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104 | items: { enum: ALL_OPERATORS },
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105 | minItems: 2,
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106 | uniqueItems: true
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107 | },
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108 | uniqueItems: true
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109 | },
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110 | allowSamePrecedence: {
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111 | type: "boolean",
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112 | default: true
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113 | }
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114 | },
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115 | additionalProperties: false
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116 | }
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117 | ],
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118 |
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119 | messages: {
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120 | unexpectedMixedOperator: "Unexpected mix of '{{leftOperator}}' and '{{rightOperator}}'."
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121 | }
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122 | },
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123 |
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124 | create(context) {
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125 | const sourceCode = context.getSourceCode();
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126 | const options = normalizeOptions(context.options[0]);
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127 |
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128 | /**
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129 | * Checks whether a given node should be ignored by options or not.
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130 | * @param {ASTNode} node A node to check. This is a BinaryExpression
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131 | * node or a LogicalExpression node. This parent node is one of
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132 | * them, too.
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133 | * @returns {boolean} `true` if the node should be ignored.
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134 | */
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135 | function shouldIgnore(node) {
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136 | const a = node;
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137 | const b = node.parent;
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138 |
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139 | return (
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140 | !includesBothInAGroup(options.groups, a.operator, b.type === "ConditionalExpression" ? "?:" : b.operator) ||
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141 | (
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142 | options.allowSamePrecedence &&
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143 | astUtils.getPrecedence(a) === astUtils.getPrecedence(b)
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144 | )
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145 | );
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146 | }
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147 |
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148 | /**
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149 | * Checks whether the operator of a given node is mixed with parent
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150 | * node's operator or not.
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151 | * @param {ASTNode} node A node to check. This is a BinaryExpression
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152 | * node or a LogicalExpression node. This parent node is one of
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153 | * them, too.
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154 | * @returns {boolean} `true` if the node was mixed.
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155 | */
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156 | function isMixedWithParent(node) {
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157 |
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158 | return (
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159 | node.operator !== node.parent.operator &&
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160 | !astUtils.isParenthesised(sourceCode, node)
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161 | );
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162 | }
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163 |
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164 | /**
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165 | * Gets the operator token of a given node.
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166 | * @param {ASTNode} node A node to check. This is a BinaryExpression
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167 | * node or a LogicalExpression node.
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168 | * @returns {Token} The operator token of the node.
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169 | */
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170 | function getOperatorToken(node) {
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171 | return sourceCode.getTokenAfter(getChildNode(node), astUtils.isNotClosingParenToken);
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172 | }
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173 |
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174 | /**
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175 | * Reports both the operator of a given node and the operator of the
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176 | * parent node.
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177 | * @param {ASTNode} node A node to check. This is a BinaryExpression
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178 | * node or a LogicalExpression node. This parent node is one of
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179 | * them, too.
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180 | * @returns {void}
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181 | */
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182 | function reportBothOperators(node) {
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183 | const parent = node.parent;
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184 | const left = (getChildNode(parent) === node) ? node : parent;
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185 | const right = (getChildNode(parent) !== node) ? node : parent;
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186 | const data = {
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187 | leftOperator: left.operator || "?:",
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188 | rightOperator: right.operator || "?:"
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189 | };
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190 |
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191 | context.report({
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192 | node: left,
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193 | loc: getOperatorToken(left).loc,
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194 | messageId: "unexpectedMixedOperator",
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195 | data
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196 | });
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197 | context.report({
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198 | node: right,
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199 | loc: getOperatorToken(right).loc,
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200 | messageId: "unexpectedMixedOperator",
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201 | data
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202 | });
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203 | }
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204 |
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205 | /**
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206 | * Checks between the operator of this node and the operator of the
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207 | * parent node.
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208 | * @param {ASTNode} node A node to check.
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209 | * @returns {void}
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210 | */
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211 | function check(node) {
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212 | if (
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213 | TARGET_NODE_TYPE.test(node.parent.type) &&
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214 | isMixedWithParent(node) &&
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215 | !shouldIgnore(node)
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216 | ) {
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217 | reportBothOperators(node);
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218 | }
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219 | }
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220 |
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221 | return {
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222 | BinaryExpression: check,
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223 | LogicalExpression: check
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224 | };
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225 | }
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226 | };
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