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