/**
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* @fileoverview An object that caches and applies source code fixes.
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* @author Nicholas C. Zakas
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*/
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"use strict";
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//------------------------------------------------------------------------------
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// Requirements
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//------------------------------------------------------------------------------
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const debug = require("debug")("eslint:source-code-fixer");
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//------------------------------------------------------------------------------
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// Helpers
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//------------------------------------------------------------------------------
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const BOM = "\uFEFF";
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/**
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* Compares items in a messages array by range.
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* @param {Message} a The first message.
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* @param {Message} b The second message.
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* @returns {int} -1 if a comes before b, 1 if a comes after b, 0 if equal.
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* @private
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*/
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function compareMessagesByFixRange(a, b) {
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return a.fix.range[0] - b.fix.range[0] || a.fix.range[1] - b.fix.range[1];
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}
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/**
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* Compares items in a messages array by line and column.
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* @param {Message} a The first message.
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* @param {Message} b The second message.
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* @returns {int} -1 if a comes before b, 1 if a comes after b, 0 if equal.
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* @private
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*/
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function compareMessagesByLocation(a, b) {
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return a.line - b.line || a.column - b.column;
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}
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//------------------------------------------------------------------------------
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// Public Interface
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//------------------------------------------------------------------------------
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/**
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* Utility for apply fixes to source code.
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* @constructor
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*/
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function SourceCodeFixer() {
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Object.freeze(this);
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}
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/**
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* Applies the fixes specified by the messages to the given text. Tries to be
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* smart about the fixes and won't apply fixes over the same area in the text.
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* @param {string} sourceText The text to apply the changes to.
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* @param {Message[]} messages The array of messages reported by ESLint.
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* @param {boolean|Function} [shouldFix=true] Determines whether each message should be fixed
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* @returns {Object} An object containing the fixed text and any unfixed messages.
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*/
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SourceCodeFixer.applyFixes = function(sourceText, messages, shouldFix) {
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debug("Applying fixes");
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if (shouldFix === false) {
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debug("shouldFix parameter was false, not attempting fixes");
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return {
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fixed: false,
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messages,
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output: sourceText
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};
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}
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// clone the array
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const remainingMessages = [],
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fixes = [],
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bom = sourceText.startsWith(BOM) ? BOM : "",
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text = bom ? sourceText.slice(1) : sourceText;
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let lastPos = Number.NEGATIVE_INFINITY,
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output = bom;
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/**
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* Try to use the 'fix' from a problem.
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* @param {Message} problem The message object to apply fixes from
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* @returns {boolean} Whether fix was successfully applied
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*/
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function attemptFix(problem) {
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const fix = problem.fix;
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const start = fix.range[0];
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const end = fix.range[1];
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// Remain it as a problem if it's overlapped or it's a negative range
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if (lastPos >= start || start > end) {
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remainingMessages.push(problem);
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return false;
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}
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// Remove BOM.
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if ((start < 0 && end >= 0) || (start === 0 && fix.text.startsWith(BOM))) {
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output = "";
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}
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// Make output to this fix.
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output += text.slice(Math.max(0, lastPos), Math.max(0, start));
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output += fix.text;
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lastPos = end;
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return true;
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}
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messages.forEach(problem => {
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if (Object.prototype.hasOwnProperty.call(problem, "fix")) {
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fixes.push(problem);
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} else {
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remainingMessages.push(problem);
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}
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});
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if (fixes.length) {
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debug("Found fixes to apply");
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let fixesWereApplied = false;
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for (const problem of fixes.sort(compareMessagesByFixRange)) {
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if (typeof shouldFix !== "function" || shouldFix(problem)) {
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attemptFix(problem);
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/*
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* The only time attemptFix will fail is if a previous fix was
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* applied which conflicts with it. So we can mark this as true.
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*/
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fixesWereApplied = true;
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} else {
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remainingMessages.push(problem);
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}
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}
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output += text.slice(Math.max(0, lastPos));
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return {
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fixed: fixesWereApplied,
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messages: remainingMessages.sort(compareMessagesByLocation),
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output
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};
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}
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debug("No fixes to apply");
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return {
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fixed: false,
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messages,
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output: bom + text
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};
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};
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module.exports = SourceCodeFixer;
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