Hashbrown777/repairBrokenXML.js

## repairBrokenXML.js
//build regexes without worrying about
// - double-backslashing
// - adding whitespace for readability
// - adding in comments
const clean = (piece) => (piece
    .replace(/((^|\n)(?:[^\/\\]|\/[^*\/]|\\.)*?)\s*\/\*(?:[^*]|\*[^\/])*(\*\/|)/g, '$1')
    .replace(/((^|\n)(?:[^\/\\]|\/[^\/]|\\.)*?)\s*\/\/[^\n]*/g, '$1')
    .replace(/\n\s*/g, '')
);
const regex = ({raw}, ...interpolations) => (
    new RegExp(interpolations.reduce(
        (regex, insert, index) => (regex + insert + clean(raw[index + 1])),
        clean(raw[0])
    ))
);

const xfcwCache = {};
const xmlFixClosedWithin = (what = '[^\s<>"/\\=&]+') => ([xfcwCache[what] || (xfcwCache[what] = regex`
	(?<=<)(${what})(\s(?:[^>"/]|"[^"]*")*|)(>
		(?:
			[^<]
			|<(?!\1[\s<>"/\\=&])([^\s<>"/\\=&]+)(?:
				\s(?:
					[^>"/]
					|"[^"]*"
				)*
				|
			)(?:
				\/>
				|>[^<]*<\/\4>
			)
		)*
	<\/)(?!\1)([^\s<>"/\\=&]+)(?=>)
`), '$1$2$3$1></$5><$1$2']);

const xfowCache = {};
const xmlFixOpenedWithin = (what = '[^\s<>"/\\=&]+') => ([xfowCache[what] || (xfowCache[what] = regex`
	(?<=<)(${what})(\s(?:[^>"/]|"[^"]*")*|)(>
		(?:
			[^<]
			|<(?!\1[\s<>"/\\=&])([^\s<>"/\\=&]+)(?:
				\s(?:
					[^>"/]
					|"[^"]*"
				)*
				|
			)(?:
				\/>
				|>[^<]*<\/\4>
			)
			|</(?!\1)(?:[\s<>"/\\=&]+)>
		)*
	<)([^\s<>"/\\=&]+)(\s(?:[^>"/]|"[^"]*")*|)(?=>
		(?:
			[^<]
			|<(?!(?:\1|\5)[\s<>"/\\=&])[^\s<>"/\\=&]+(?:
				\s(?:
					[^>"/]
					|"[^"]*"
				)*
				|
			)\/?>
			|</(?!\1|\5)(?:[\s<>"/\\=&]+)>
		)*
	<\/\1>)
`), '$1$2$3/$1><$5$6><$1$2']);

const fixXML = (xml, fixes = [xmlFixClosedWithin(), xmlFixOpenedWithin()]) => {
	if ((typeof fixes == 'string') || fixes instanceof String)
		fixes = [xmlFixClosedWithin(fixes), xmlFixOpenedWithin(fixes)];
	let iterations = 10;
	for (
		let change = '';
		change != xml && --iterations && (change = xml);
	) {
		for (let [problem, fix] of fixes)
			xml = xml.replace(problem, fix);
	}
	if (!iterations)
		throw new Error('Didn\'t manage to rectify the xml within 10 changes');
	return xml;
};
	//build regexes without worrying about
	// - double-backslashing
	// - adding whitespace for readability
	// - adding in comments
	const clean = (piece) => (piece
	.replace(/((^\|\n)(?:[^\/\\]\|\/[^\/]\|\\.)?)\s\/\(?:[^]\|\[^\/])(\\/\|)/g, '$1')
	.replace(/((^\|\n)(?:[^\/\\]\|\/[^\/]\|\\.)?)\s\/\/[^\n]*/g, '$1')
	.replace(/\n\s*/g, '')
	);
	const regex = ({raw}, ...interpolations) => (
	new RegExp(interpolations.reduce(
	(regex, insert, index) => (regex + insert + clean(raw[index + 1])),
	clean(raw[0])
	))
	);

	const xfcwCache = {};
	const xmlFixClosedWithin = (what = '[^\s<>"/\\=&]+') => ([xfcwCache[what] \|\| (xfcwCache[what] = regex`
	(?<=<)(${what})(\s(?:[^>"/]\|"[^"]")\|)(>
	(?:
	[^<]
	\|<(?!\1[\s<>"/\\=&])([^\s<>"/\\=&]+)(?:
	\s(?:
	[^>"/]
	\|"[^"]*"
	)*
	\|
	)(?:
	\/>
	\|>[^<]*<\/\4>
	)
	)*
	<\/)(?!\1)([^\s<>"/\\=&]+)(?=>)
	`), '$1$2$3$1></$5><$1$2']);

	const xfowCache = {};
	const xmlFixOpenedWithin = (what = '[^\s<>"/\\=&]+') => ([xfowCache[what] \|\| (xfowCache[what] = regex`
	(?<=<)(${what})(\s(?:[^>"/]\|"[^"]")\|)(>
	(?:
	[^<]
	\|<(?!\1[\s<>"/\\=&])([^\s<>"/\\=&]+)(?:
	\s(?:
	[^>"/]
	\|"[^"]*"
	)*
	\|
	)(?:
	\/>
	\|>[^<]*<\/\4>
	)
	\|</(?!\1)(?:[\s<>"/\\=&]+)>
	)*
	<)([^\s<>"/\\=&]+)(\s(?:[^>"/]\|"[^"]")\|)(?=>
	(?:
	[^<]
	\|<(?!(?:\1\|\5)[\s<>"/\\=&])[^\s<>"/\\=&]+(?:
	\s(?:
	[^>"/]
	\|"[^"]*"
	)*
	\|
	)\/?>
	\|</(?!\1\|\5)(?:[\s<>"/\\=&]+)>
	)*
	<\/\1>)
	`), '$1$2$3/$1><$5$6><$1$2']);

	const fixXML = (xml, fixes = [xmlFixClosedWithin(), xmlFixOpenedWithin()]) => {
	if ((typeof fixes == 'string') \|\| fixes instanceof String)
	fixes = [xmlFixClosedWithin(fixes), xmlFixOpenedWithin(fixes)];
	let iterations = 10;
	for (
	let change = '';
	change != xml && --iterations && (change = xml);
	) {
	for (let [problem, fix] of fixes)
	xml = xml.replace(problem, fix);
	}
	if (!iterations)
	throw new Error('Didn\'t manage to rectify the xml within 10 changes');
	return xml;
	};