[dotnet] Add dotnet projects and examples

+ Sitemap generator I created while learning the dispose pattern
+ Testing project for learning general C#

dotnet/sitemap/SiteMapLibrary/SiteMap.cs

@@ -0,0 +1,114 @@
+using System.Text.RegularExpressions;
+
+namespace SiteMapLibrary;
+
+public class SiteMap : IDisposable
+{
+  private HttpClient _client;
+  private HashSet<string> _foundUrls;
+  private HashSet<string> _visitedUrls;
+  private Queue<string> _visitQueue;
+  private bool _disposed = false;
+  private XmlManager XmlManager { get; set; }
+  public string? Url { get; private set; }
+  public Regex Regexp { get; set; }
+
+  public SiteMap(string url, string savepath, Regex pattern)
+  {
+    Url = url;
+    _client = new HttpClient();
+    _foundUrls = new HashSet<string>();
+    _visitedUrls = new HashSet<string>();
+    _visitQueue = new Queue<string>();
+    Regexp = pattern;
+    XmlManager = new XmlManager(savepath);
+  }
+
+  public SiteMap(string url, XmlManager mgr, Regex pattern)
+  {
+    _client = new HttpClient();
+    _foundUrls = new HashSet<string>();
+    _visitedUrls = new HashSet<string>();
+    _visitQueue = new Queue<string>();
+    Regexp = pattern;
+    Url = url;
+    XmlManager = mgr;
+  }
+
+  public async Task Crawl()
+  {
+    while (Url != null)
+    {
+      _visitedUrls.Add(Url);
+      using var content = await _client.GetAsync(Url);
+      if (!content.IsSuccessStatusCode)
+      {
+        Console.WriteLine($"{content.StatusCode} on url: {Url}");
+        NextUrl();
+        continue;
+      }
+
+      var m = Regexp.Match(await content.Content.ReadAsStringAsync());
+      while (m.Success)
+      {
+        foreach (Group group in m.Groups)
+        {
+          if (_foundUrls.Add(group.Value))
+          {
+            Console.WriteLine(group.Value);
+            // Console.WriteLine(content.Content.Headers.LastModified);
+            if (!_visitedUrls.Contains(group.Value) && !_visitQueue.Contains(group.Value))
+            {
+              _visitQueue.Enqueue(group.Value);
+            }
+          }
+        }
+
+        m = m.NextMatch();
+      }
+
+      NextUrl();
+      content.Dispose();
+    }
+    WriteXml();
+  }
+
+  private void WriteXml()
+  {
+    List<string> urls = new List<string>(_visitedUrls.OrderBy(k => k.Length).ToArray());
+    foreach (string url in urls)
+    {
+      XmlManager.AddUrl(url);
+    }
+    XmlManager.Save();
+  }
+
+  private void NextUrl()
+  {
+    if (_visitQueue.Count == 0)
+    {
+      Url = null;
+      return;
+    }
+    Url = _visitQueue.Dequeue();
+  }
+
+  public void Dispose()
+  {
+    Dispose(true);
+    GC.SuppressFinalize(this);
+  }
+
+  public void Dispose(bool disposing)
+  {
+    if (!_disposed)
+    {
+      if (disposing)
+      {
+        _client.Dispose();
+      }
+
+      _disposed = true;
+    }
+  }
+}

dotnet/sitemap/SiteMapLibrary/SiteMapLibrary.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net6.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <RootNamespace>SiteMap</RootNamespace>
+  </PropertyGroup>
+
+</Project>

dotnet/sitemap/SiteMapLibrary/XmlManager.cs

@@ -0,0 +1,59 @@
+using System.Xml;
+
+namespace SiteMapLibrary;
+
+public class XmlManager
+{
+  private XmlDocument XmlDocument { get; set; }
+  private XmlDeclaration XmlDeclaration { get; set; } 
+  private XmlElement XmlUrlset { get; set; }
+  private string Path { get; set; }
+
+  public XmlManager(string path,
+    string version="1.0", string encoding="utf-8", string standalone="")
+  {
+    XmlDocument = new XmlDocument();
+    XmlDeclaration = XmlDocument.CreateXmlDeclaration(version, encoding, standalone);
+    XmlDocument.AppendChild(XmlDeclaration);
+    XmlUrlset = XmlDocument.CreateElement("urlset");
+    XmlDocument.AppendChild(XmlUrlset);
+    Path = path;
+  }
+
+  ~XmlManager()
+  {
+    Save();
+  }
+  
+  public void AddUrl(string url)
+  {
+    XmlElement newUrl = XmlDocument.CreateElement("url");
+    XmlUrlset.AppendChild(newUrl);
+    XmlElement newLoc = XmlDocument.CreateElement("loc");
+    newLoc.InnerText = url;
+    newUrl.AppendChild(newLoc);
+    var lastmod = XmlDocument.CreateElement("lastmod");
+    lastmod.InnerText = DateTime.Now.Year.ToString() 
+                        + '-' + DateTime.Now.Month.ToString()
+                        + '-' + DateTime.Now.Day;
+    newUrl.AppendChild(lastmod);
+    var changeFreq = XmlDocument.CreateElement("changefreq");
+    changeFreq.InnerText = "daily";
+    newUrl.AppendChild(changeFreq);
+    var priority = XmlDocument.CreateElement("priority");
+    priority.InnerText = "0.5";
+    newUrl.AppendChild(priority);
+  }
+  
+  public void Save()
+  {
+    if (Path == "Console.Out")
+    {
+      XmlDocument.Save(Console.Out);
+    }
+    else
+    {
+      XmlDocument.Save(Path);
+    }
+  }
+}