xpath2css/index.js at master · roman-rybalko/xpath2css · GitHub

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/**
 *
 * The simplest XPATH expression to CSS/jQuery selector conversion tool.
 *
 * https://github.com/roman-rybalko/xpath2css
 *
 */

'use strict';

function xpath2css(xpath) {
	if (xpath.match(/__ESCAPE__/))
		throw new Error('"__ESCAPE__" clause is reserved');

	function escape(str) {
		var codes = [];
		for (var i in str)
			codes.push(str.charCodeAt(i));
		return '__ESCAPE__' + codes.join('_');
	}
	function unescape(str) {
		return str.replace(/__ESCAPE__([\d_]+)/g, function(s, m1) {
			var codes = m1.split('_');
			var decoded = '';
			for (var i in codes)
				decoded += String.fromCharCode(codes[i]);
			return decoded;
		});
	}

	xpath = xpath  // strings pre-processing
		// escape strings, will not escape empty strings ("") or unquoted strings (string-without-quotes)
		.replace(/(=|,|\[|and)(\s*)("|')(.*?[^\\]\3)/g, function(s, m1, m2, m3, m4) {return m1 + m2 + escape(m3 + m4);})
		.replace(/\(:.+?:\)/g, '')  // remove XPATH 2.0 comments (after string escaping since a string containing a comment is a valid expression)
	;

	if (xpath.match(/\s+or\s+/))
		throw new Error('xpath "or" clause is not supported');  // ambiguous
	if (xpath.match(/::/))
		throw new Error('xpath axes (/axis::) are not supported');
	if (xpath.match(/\/\.\./))
		throw new Error('xpath parent (/..) clause is not supported');  // unsupported by css, see https://css-tricks.com/parent-selectors-in-css/
	if (xpath.match(/\/\/\./))
		throw new Error('xpath clause "//." is not supported');  // dunno what to do with it

	xpath = xpath  // convert "and" clause before normalization
		.replace(/\s+and\s+/g, '][')  // "and" clause
	;

	xpath = xpath  // normalization (extra space, fixes)
		.replace(/^\s+/, '')  // extra space
		.replace(/\s+$/, '')  // extra space
		.replace(/\s*\[\s*/g, '[')  // extra space
		.replace(/\s*\]\s*/g, ']')  // extra space
		.replace(/\s*\(\s*/g, '(')  // extra space
		.replace(/\s*\)\s*/g, ')')  // extra space
		.replace(/\s*(\/+)\s*/g, '$1')  // extra space
		.replace(/\s*,\s*/g, ',')  // extra space
		.replace(/\s*=\s*/g, '=')  // extra space
		.replace(/\/\/+/g, '//')  // fix "////" "///" clauses
	;

	if (xpath.match(/\]\[\d+\]|\)\[\d+\]/))
		throw new Error('xpath clauses "x[...][n]", "(...)[n]" (node-set index) are not supported, though "*[n]", "x[n]", "...[n][...]" (:nth-child, :nth-of-type) are ok');
	if (xpath.match(/.\/\/[^\/]+\[\d+\]/))
		throw new Error('xpath clause "//y//x[n]" is not supported, use "//y//z/x[n]" instead (specify a parent for an indexed tag), though "//x[n]" (:eq) is ok');
	if (xpath.match(/not\(/))
		throw new Error('xpath clause "not(...)" is unsupported');

	xpath = xpath  // converting
		.replace(/^\/\/([^\/]+)\[(\d+)\]/, function(s, m1, m2) {return m1 + ':eq(' + (m2 - 1) + ')'})  // index (before "//" converting)
		.replace(/^\/+/, '')  // remove root "/" since it's irrelevant in css
		.replace(/\/\./g, '')  // self (parent clause "/.." should be handled before here)
		.replace(/\/\//g, ' ')  // descendant
		.replace(/\//g, ' > ')  // child
		.replace(/position\(\)=/g, '')  // "position() = n" clause (preprocess, will be handled further in index)
		.replace(/\*\[(\d+)\]/g, '*:nth-child($1)')  // index
		.replace(/\[(\d+)\]/g, ':nth-of-type($1)')  // index
		.replace(/@/g, '')  // attribute
		.replace(/\[contains\(text\(\),(\S+?)\)\]/g, ':contains($1)')  // "contains(text(), ...)" clause (jQuery only)
		.replace(/\[contains\((\S+?),(\S+?)\)\]/g, '[$1*=$2]')  // "contains" clause
		.replace(/starts\-with\((\S+?),(\S+?)\)/g, '$1^=$2')  // "starts-with" clause
		.replace(/ends\-with\((\S+?),(\S+?)\)/g, '$1\$=$2')  // "ends-with" clause
		.replace(/\[__ESCAPE__\S+?\]/g, '')  // always-true-string as a comment
	;

	xpath = unescape(xpath);  // unescape strings

	return xpath;
}

module.exports = xpath2css;