1 | /**
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2 | * @fileoverview An object that caches and applies source code fixes.
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3 | * @author Nicholas C. Zakas
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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 debug = require("debug")("eslint:text-fixer");
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12 |
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13 | //------------------------------------------------------------------------------
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14 | // Helpers
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15 | //------------------------------------------------------------------------------
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16 |
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17 | const BOM = "\uFEFF";
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18 |
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19 | /**
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20 | * Compares items in a messages array by range.
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21 | * @param {Message} a The first message.
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22 | * @param {Message} b The second message.
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23 | * @returns {int} -1 if a comes before b, 1 if a comes after b, 0 if equal.
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24 | * @private
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25 | */
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26 | function compareMessagesByFixRange(a, b) {
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27 | return a.fix.range[0] - b.fix.range[0] || a.fix.range[1] - b.fix.range[1];
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28 | }
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29 |
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30 | /**
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31 | * Compares items in a messages array by line and column.
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32 | * @param {Message} a The first message.
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33 | * @param {Message} b The second message.
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34 | * @returns {int} -1 if a comes before b, 1 if a comes after b, 0 if equal.
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35 | * @private
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36 | */
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37 | function compareMessagesByLocation(a, b) {
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38 | return a.line - b.line || a.column - b.column;
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39 | }
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40 |
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41 | //------------------------------------------------------------------------------
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42 | // Public Interface
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43 | //------------------------------------------------------------------------------
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44 |
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45 | /**
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46 | * Utility for apply fixes to source code.
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47 | * @constructor
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48 | */
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49 | function SourceCodeFixer() {
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50 | Object.freeze(this);
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51 | }
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52 |
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53 | /**
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54 | * Applies the fixes specified by the messages to the given text. Tries to be
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55 | * smart about the fixes and won't apply fixes over the same area in the text.
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56 | * @param {string} sourceText The text to apply the changes to.
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57 | * @param {Message[]} messages The array of messages reported by ESLint.
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58 | * @param {boolean|Function} [shouldFix=true] Determines whether each message should be fixed
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59 | * @returns {Object} An object containing the fixed text and any unfixed messages.
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60 | */
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61 | SourceCodeFixer.applyFixes = function(sourceText, messages, shouldFix) {
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62 | debug("Applying fixes");
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63 |
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64 | if (shouldFix === false) {
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65 | debug("shouldFix parameter was false, not attempting fixes");
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66 | return {
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67 | fixed: false,
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68 | messages,
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69 | output: sourceText
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70 | };
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71 | }
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72 |
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73 | // clone the array
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74 | const remainingMessages = [],
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75 | fixes = [],
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76 | bom = sourceText.startsWith(BOM) ? BOM : "",
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77 | text = bom ? sourceText.slice(1) : sourceText;
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78 | let lastPos = Number.NEGATIVE_INFINITY,
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79 | output = bom;
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80 |
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81 | /**
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82 | * Try to use the 'fix' from a problem.
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83 | * @param {Message} problem The message object to apply fixes from
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84 | * @returns {boolean} Whether fix was successfully applied
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85 | */
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86 | function attemptFix(problem) {
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87 | const fix = problem.fix;
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88 | const start = fix.range[0];
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89 | const end = fix.range[1];
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90 |
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91 | // Remain it as a problem if it's overlapped or it's a negative range
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92 | if (lastPos >= start || start > end) {
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93 | remainingMessages.push(problem);
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94 | return false;
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95 | }
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96 |
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97 | // Remove BOM.
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98 | if ((start < 0 && end >= 0) || (start === 0 && fix.text.startsWith(BOM))) {
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99 | output = "";
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100 | }
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101 |
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102 | // Make output to this fix.
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103 | output += text.slice(Math.max(0, lastPos), Math.max(0, start));
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104 | output += fix.text;
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105 | lastPos = end;
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106 | return true;
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107 | }
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108 |
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109 | messages.forEach(problem => {
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110 | if (problem.hasOwnProperty("fix")) {
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111 | fixes.push(problem);
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112 | } else {
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113 | remainingMessages.push(problem);
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114 | }
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115 | });
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116 |
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117 | if (fixes.length) {
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118 | debug("Found fixes to apply");
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119 | let fixesWereApplied = false;
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120 |
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121 | for (const problem of fixes.sort(compareMessagesByFixRange)) {
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122 | if (typeof shouldFix !== "function" || shouldFix(problem)) {
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123 | attemptFix(problem);
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124 |
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125 | /*
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126 | * The only time attemptFix will fail is if a previous fix was
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127 | * applied which conflicts with it. So we can mark this as true.
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128 | */
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129 | fixesWereApplied = true;
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130 | } else {
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131 | remainingMessages.push(problem);
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132 | }
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133 | }
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134 | output += text.slice(Math.max(0, lastPos));
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135 |
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136 | return {
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137 | fixed: fixesWereApplied,
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138 | messages: remainingMessages.sort(compareMessagesByLocation),
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139 | output
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140 | };
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141 | }
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142 |
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143 | debug("No fixes to apply");
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144 | return {
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145 | fixed: false,
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146 | messages,
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147 | output: bom + text
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148 | };
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149 |
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150 | };
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151 |
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152 | module.exports = SourceCodeFixer;
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