Parser which represents string of s-expressions as list of strings and nested lists

SExpParser.hx

import js.Browser;
import js.html.ButtonElement;
import js.html.TextAreaElement;

/**
 * @author Anton
 * s-expressions parser
 */

class Test 
{
	public function new()
	{
		var _in : TextAreaElement = Browser.document.createTextAreaElement();
		var _out : TextAreaElement = Browser.document.createTextAreaElement();
		var _button : ButtonElement = Browser.document.createButtonElement();
		
		_in.style.width = _in.style.height = _out.style.width = _out.style.height = "250px";
		_in.textContent =  "(+ 5 (* 3 5) 5)\n(+ 5 6)";
		_button.textContent = "Click";
		
		Browser.document.body.appendChild(_in);
		Browser.document.body.appendChild(_out);
		Browser.document.body.appendChild(_button);
		
		var pars = new SExpParser(_in.textContent);
		
		_button.onclick = function(e) {			
			pars.expression = _in.value;
			var parsed = pars.parse();
			_out.textContent = parsed.toString();
			trace(parsed);
		}
	}
	
	static function main() 
	{
		new Test();
	}
	
}

class SExpParser
{
	public var expression : String;
	
	public function new(expression : String)
	{
		this.expression = expression;
	}
	
	public function parse() : List<Dynamic>
	{
		var list : List<Dynamic> = new List<Dynamic>();
		list.add(new List<Dynamic>());
		
		var isStringEntry = false;
		var isSymbolEntry = false;
		var dataString = "";
		
		for (i in 0...expression.length)
		{
			switch (expression.charAt(i))
			{
				case '(':
					if (isStringEntry)
						dataString += '(';
					else
						list.add(new List<Dynamic>());
				case ')':
					if (isStringEntry)
						dataString += ')';
					else
					{
						if (dataString != "")
						{
							list.last().add(dataString);
							dataString = "";
						}
						if (isSymbolEntry) isSymbolEntry = false;
						
						var temp = list.last();
						list.remove(list.last());
						list.last().add(temp);
					}	
				case '"':
					if (isStringEntry)
					{
						dataString += '"';
						list.last().add(dataString);
						dataString = "";
						isStringEntry = false;
					}
					else
					{
						isStringEntry = true;
						dataString = '"';
					}
				case " ", "\n", "\t":
					if (isStringEntry)
						dataString += ' ';
					else
					{
						if (isSymbolEntry)
						{
							list.last().add(dataString);
							dataString = "";
							isSymbolEntry = false;
						}
					}
				default:
					if (!isSymbolEntry) isSymbolEntry = true;
					dataString += expression.charAt(i);
			}
		}
		
		return list.first();
	}
}