Pretty prints xml

prettyxml.js

/**
 *	Pretty prints xml
 *
 *	@param	String	ugly xml
 *	@return	String	prettier xml
 *	@author Schell Scivally
 *	@since	Sun Mar 14 16:16:50 PDT 2010
 */
var formatXml = this.formatXml = function (xml) {
	var reg = /(>)(<)(\/*)/g;
	var wsexp = / *(.*) +\n/g;
	var contexp = /(<.+>)(.+\n)/g;
	xml = xml.replace(reg, '$1\n$2$3').replace(wsexp, '$1\n').replace(contexp, '$1\n$2');
	var pad = 0;
	var formatted = '';
	var lines = xml.split('\n');
	var indent = 0;
	var lastType = 'other';
	// 4 types of tags - single, closing, opening, other (text, doctype, comment) - 4*4 = 16 transitions 
	var transitions = {
		'single->single'    : 0,
		'single->closing'   : -1,
		'single->opening'   : 0,
		'single->other'     : 0,
		'closing->single'   : 0,
		'closing->closing'  : -1,
		'closing->opening'  : 0,
		'closing->other'    : 0,
		'opening->single'   : 1,
		'opening->closing'  : 0, // if there's an open to a close, they probably should have used a single, oh well
		'opening->opening'  : 1,
		'opening->other'    : 1,
		'other->single'     : 0,
		'other->closing'    : -1,
		'other->opening'    : 0,
		'other->other'      : 0
	};

	for (var i=0; i < lines.length; i++) {
		var ln = lines[i];
		var single = /<.+\/>/.test(ln); // is this line a single tag? ex. <br />
		var closing = /<\/.+>/.test(ln); // is this a closing tag? ex. </a>
		var opening = /<[^!].*>/.test(ln); // is this even a tag (that's not <!something>)
		var type = single ? 'single' : closing ? 'closing' : opening ? 'opening' : 'other';
		var fromTo = lastType + '->' + type;
		lastType = type;
		var padding = '';

		indent += transitions[fromTo];
		for (var j = 0; j < indent; j++) {
			padding += '    ';
		}

		formatted += padding + ln + '\n';
	}

	return formatted;
};