1 | /**
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2 | * @fileoverview A rule to ensure whitespace before blocks.
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3 | * @author Mathias Schreck <https://github.com/lo1tuma>
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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 spacing before blocks",
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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/space-before-blocks"
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21 | },
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22 |
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23 | fixable: "whitespace",
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24 |
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25 | schema: [
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26 | {
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27 | oneOf: [
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28 | {
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29 | enum: ["always", "never"]
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30 | },
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31 | {
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32 | type: "object",
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33 | properties: {
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34 | keywords: {
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35 | enum: ["always", "never"]
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36 | },
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37 | functions: {
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38 | enum: ["always", "never"]
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39 | },
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40 | classes: {
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41 | enum: ["always", "never"]
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42 | }
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43 | },
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44 | additionalProperties: false
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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 |
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51 | create(context) {
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52 | const config = context.options[0],
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53 | sourceCode = context.getSourceCode();
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54 | let checkFunctions = true,
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55 | checkKeywords = true,
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56 | checkClasses = true;
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57 |
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58 | if (typeof config === "object") {
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59 | checkFunctions = config.functions !== "never";
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60 | checkKeywords = config.keywords !== "never";
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61 | checkClasses = config.classes !== "never";
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62 | } else if (config === "never") {
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63 | checkFunctions = false;
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64 | checkKeywords = false;
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65 | checkClasses = false;
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66 | }
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67 |
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68 | /**
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69 | * Checks whether or not a given token is an arrow operator (=>) or a keyword
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70 | * in order to avoid to conflict with `arrow-spacing` and `keyword-spacing`.
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71 | *
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72 | * @param {Token} token - A token to check.
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73 | * @returns {boolean} `true` if the token is an arrow operator.
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74 | */
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75 | function isConflicted(token) {
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76 | return (token.type === "Punctuator" && token.value === "=>") || token.type === "Keyword";
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77 | }
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78 |
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79 | /**
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80 | * Checks the given BlockStatement node has a preceding space if it doesn’t start on a new line.
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81 | * @param {ASTNode|Token} node The AST node of a BlockStatement.
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82 | * @returns {void} undefined.
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83 | */
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84 | function checkPrecedingSpace(node) {
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85 | const precedingToken = sourceCode.getTokenBefore(node);
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86 |
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87 | if (precedingToken && !isConflicted(precedingToken) && astUtils.isTokenOnSameLine(precedingToken, node)) {
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88 | const hasSpace = sourceCode.isSpaceBetweenTokens(precedingToken, node);
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89 | const parent = context.getAncestors().pop();
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90 | let requireSpace;
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91 |
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92 | if (parent.type === "FunctionExpression" || parent.type === "FunctionDeclaration") {
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93 | requireSpace = checkFunctions;
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94 | } else if (node.type === "ClassBody") {
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95 | requireSpace = checkClasses;
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96 | } else {
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97 | requireSpace = checkKeywords;
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98 | }
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99 |
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100 | if (requireSpace) {
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101 | if (!hasSpace) {
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102 | context.report({
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103 | node,
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104 | message: "Missing space before opening brace.",
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105 | fix(fixer) {
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106 | return fixer.insertTextBefore(node, " ");
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107 | }
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108 | });
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109 | }
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110 | } else {
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111 | if (hasSpace) {
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112 | context.report({
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113 | node,
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114 | message: "Unexpected space before opening brace.",
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115 | fix(fixer) {
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116 | return fixer.removeRange([precedingToken.range[1], node.range[0]]);
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117 | }
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118 | });
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119 | }
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120 | }
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121 | }
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122 | }
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123 |
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124 | /**
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125 | * Checks if the CaseBlock of an given SwitchStatement node has a preceding space.
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126 | * @param {ASTNode} node The node of a SwitchStatement.
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127 | * @returns {void} undefined.
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128 | */
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129 | function checkSpaceBeforeCaseBlock(node) {
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130 | const cases = node.cases;
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131 | let openingBrace;
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132 |
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133 | if (cases.length > 0) {
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134 | openingBrace = sourceCode.getTokenBefore(cases[0]);
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135 | } else {
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136 | openingBrace = sourceCode.getLastToken(node, 1);
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137 | }
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138 |
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139 | checkPrecedingSpace(openingBrace);
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140 | }
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141 |
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142 | return {
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143 | BlockStatement: checkPrecedingSpace,
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144 | ClassBody: checkPrecedingSpace,
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145 | SwitchStatement: checkSpaceBeforeCaseBlock
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146 | };
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147 |
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148 | }
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149 | };
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