Re: [ADVANCED-DOTNET] Regex for parsing XML - Foolish?

[Larry O'Brien]

XmlTextReader looks like the clear winner in terms of performance:

Reg Ex:         00:00:00.3805472
XMLTextReader:  00:00:00.1702448
XPathNavigator: 00:00:00.3104464

Thanks for the thoughts!
Larry

using System;
using NUnit.Framework;
using System.Xml;
using System.Xml.XPath;
using System.Text.RegularExpressions;
using System.IO;
using System.Collections;

        [TestFixture]
        public class ParsingTechnique
        {
                public ParsingTechnique()
                {
                }

                [Test]
        public void TestParsingSpeed()
                {
                        string s = //very-long XML string here
                        ParsingTechnique pt = new ParsingTechnique();
                        DateTime start = DateTime.Now;
                        pt.RegExParsing("firstName", s);
                        TimeSpan duration = DateTime.Now - start;
                        Console.WriteLine("Reg Ex: " + duration);
                        start = DateTime.Now;
                        pt.StraightReader("firstName", s);
                        duration = DateTime.Now - start;
                        Console.WriteLine("XMLTextReader: " + duration);
                        start = DateTime.Now;
                        pt.XPath("firstName", s);
                        duration = DateTime.Now - start;
                        Console.WriteLine("XPathNavigator: " +
duration);
                }

                string[] RegExParsing(string elementName, string xml)
                {
                        ArrayList responses = new ArrayList();
                        Regex re = new
Regex(String.Format("<{0}>(?<value>.*?)</{0}>", elementName));
                        MatchCollection matches = re.Matches(xml);
                        foreach(Match m in matches)
                        {
                                string value = m.Groups["value"].Value;
                                responses.Add(value);
                        }
                        return (string[])
responses.ToArray(typeof(string));
                }

                string[] StraightReader(string elementName, string xml)
                {
                        ArrayList responses = new ArrayList();
                        XmlTextReader xtr = new XmlTextReader(new
StringReader(xml));
                        while(xtr.Read())
                        {
                                if(xtr.NodeType == XmlNodeType.Element
&& xtr.Name == elementName)
                                {
                                        while(xtr.NodeType !=
XmlNodeType.Text)
                                        {
                                                xtr.Read();
                                        }
                                        string val = xtr.Value;
                                        responses.Add(val);
                                }
                        }
                        xtr.Close();
                        return (string[])
responses.ToArray(typeof(string));
                }

                string[] XPath(string elementName, string  xml)
                {
                        ArrayList responses = new ArrayList();
                        XPathDocument doc = new XPathDocument(new
StringReader(xml));
                        XPathNavigator nav = doc.CreateNavigator();
                        XPathNodeIterator iter = (XPathNodeIterator)
nav.Evaluate("//"+elementName);
                        while(iter.MoveNext())
                        {
                                string val = iter.Current.Value;
                                responses.Add(val);
                        }
                        return (string[])
responses.ToArray(typeof(string));
                }
        }
}