Enable nullable reference types, modernize code

Author: cdervis

Src/Configuration.cs

@@ -21,7 +21,7 @@ namespace SharpConfig
   /// </summary>
   public class Configuration : IEnumerable<Section>
   {
-    private static CultureInfo s_cultureInfo;
+    private static CultureInfo? s_cultureInfo;
     private static char s_preferredCommentChar;
     private static char s_arrayElementSeparator;
     private static readonly Dictionary<Type, ITypeStringConverter> s_typeStringConverters;
@@ -120,8 +120,13 @@ public Section Add(string sectionName)
     /// empty.</exception>
     public bool Remove(string sectionName)
     {
-      return string.IsNullOrEmpty(sectionName) ? throw new ArgumentNullException(nameof(sectionName))
-                                               : Remove(FindSection(sectionName));
+      if (string.IsNullOrEmpty(sectionName))
+      {
+        throw new ArgumentNullException(nameof(sectionName));
+      }
+
+      var section = FindSection(sectionName);
+      return section != null && Remove(section);
     }
 
     /// <summary>
@@ -228,6 +233,11 @@ public static void RegisterTypeStringConverter(ITypeStringConverter converter)
 
       var type = converter.ConvertibleType;
 
+      if (type == null)
+      {
+        throw new ArgumentException("The converter's ConvertibleType cannot be null.", nameof(converter));
+      }
+
       if (s_typeStringConverters.ContainsKey(type))
       {
         throw new InvalidOperationException($"A converter for type '{type.FullName}' is already registered.");
@@ -277,7 +287,7 @@ public static ITypeStringConverter FindTypeStringConverter(Type type)
         type = typeof(Enum);
       }
 
-      if (!s_typeStringConverters.TryGetValue(type, out ITypeStringConverter converter))
+      if (!s_typeStringConverters.TryGetValue(type, out ITypeStringConverter? converter))
       {
         converter = FallbackConverter;
       }
@@ -302,7 +312,7 @@ public static ITypeStringConverter FindTypeStringConverter(Type type)
     /// <exception cref="ArgumentNullException">When <paramref name="filename"/> is null or empty.</exception>
     /// <exception cref="FileNotFoundException">When the specified configuration file is not
     /// found.</exception>
-    public static Configuration LoadFromFile(string filename, Encoding encoding = null)
+    public static Configuration LoadFromFile(string filename, Encoding? encoding = null)
     {
       if (string.IsNullOrEmpty(filename))
       {
@@ -331,7 +341,7 @@ public static Configuration LoadFromFile(string filename, Encoding encoding = nu
     /// </returns>
     ///
     /// <exception cref="ArgumentNullException">When <paramref name="stream"/> is null.</exception>
-    public static Configuration LoadFromStream(Stream stream, Encoding encoding = null)
+    public static Configuration LoadFromStream(Stream stream, Encoding? encoding = null)
     {
       if (stream == null)
       {
@@ -374,7 +384,7 @@ public static Configuration LoadFromString(string source)
     /// </returns>
     ///
     /// <exception cref="ArgumentNullException">When <paramref name="filename"/> is null or empty.</exception>
-    public static Configuration LoadFromBinaryFile(string filename, BinaryReader reader = null)
+    public static Configuration LoadFromBinaryFile(string filename, BinaryReader? reader = null)
     {
       if (string.IsNullOrEmpty(filename))
       {
@@ -400,7 +410,7 @@ public static Configuration LoadFromBinaryFile(string filename, BinaryReader rea
     /// </returns>
     ///
     /// <exception cref="ArgumentNullException">When <paramref name="stream"/> is null.</exception>
-    public static Configuration LoadFromBinaryStream(Stream stream, BinaryReader reader = null)
+    public static Configuration LoadFromBinaryStream(Stream stream, BinaryReader? reader = null)
     {
       return stream == null ? throw new ArgumentNullException(nameof(stream))
                             : ConfigurationReader.ReadFromBinaryStream(stream, reader);
@@ -411,7 +421,7 @@ public static Configuration LoadFromBinaryStream(Stream stream, BinaryReader rea
     /// </summary>
     ///
     /// <param name="filename">The location of the configuration file.</param>
-    public void SaveToFile(string filename) => SaveToFile(filename, null);
+    public void SaveToFile(string filename) => SaveToFile(filename, (Encoding?)null);
 
     /// <summary>
     /// Saves the configuration to a file.
@@ -422,7 +432,7 @@ public static Configuration LoadFromBinaryStream(Stream stream, BinaryReader rea
     /// is UTF8.</param>
     ///
     /// <exception cref="ArgumentNullException">When <paramref name="filename"/> is null or empty.</exception>
-    public void SaveToFile(string filename, Encoding encoding)
+    public void SaveToFile(string filename, Encoding? encoding)
     {
       if (string.IsNullOrEmpty(filename))
       {
@@ -440,7 +450,7 @@ public void SaveToFile(string filename, Encoding encoding)
     /// </summary>
     ///
     /// <param name="stream">The stream to save the configuration to.</param>
-    public void SaveToStream(Stream stream) => SaveToStream(stream, null);
+    public void SaveToStream(Stream stream) => SaveToStream(stream, (Encoding?)null);
 
     /// <summary>
     /// Saves the configuration to a stream.
@@ -451,7 +461,7 @@ public void SaveToFile(string filename, Encoding encoding)
     /// is UTF8.</param>
     ///
     /// <exception cref="ArgumentNullException">When <paramref name="stream"/> is null.</exception>
-    public void SaveToStream(Stream stream, Encoding encoding)
+    public void SaveToStream(Stream stream, Encoding? encoding)
     {
       if (stream == null)
       {
@@ -466,7 +476,7 @@ public void SaveToStream(Stream stream, Encoding encoding)
     /// </summary>
     ///
     /// <param name="filename">The location of the configuration file.</param>
-    public void SaveToBinaryFile(string filename) => SaveToBinaryFile(filename, null);
+    public void SaveToBinaryFile(string filename) => SaveToBinaryFile(filename, (BinaryWriter?)null);
 
     /// <summary>
     /// Saves the configuration to a binary file, using a specific <see cref="BinaryWriter"/>.
@@ -476,7 +486,7 @@ public void SaveToStream(Stream stream, Encoding encoding)
     /// <param name="writer">  The writer to use. Specify null to use the default writer.</param>
     ///
     /// <exception cref="ArgumentNullException">When <paramref name="filename"/> is null or empty.</exception>
-    public void SaveToBinaryFile(string filename, BinaryWriter writer)
+    public void SaveToBinaryFile(string filename, BinaryWriter? writer)
     {
       if (string.IsNullOrEmpty(filename))
       {
@@ -494,7 +504,7 @@ public void SaveToBinaryFile(string filename, BinaryWriter writer)
     /// </summary>
     ///
     /// <param name="stream">The stream to save the configuration to.</param>
-    public void SaveToBinaryStream(Stream stream) => SaveToBinaryStream(stream, null);
+    public void SaveToBinaryStream(Stream stream) => SaveToBinaryStream(stream, (BinaryWriter?)null);
 
     /// <summary>
     /// Saves the configuration to a binary file, using a specific <see cref="BinaryWriter"/>.
@@ -504,7 +514,7 @@ public void SaveToBinaryFile(string filename, BinaryWriter writer)
     /// <param name="writer">The writer to use. Specify null to use the default writer.</param>
     ///
     /// <exception cref="ArgumentNullException">When <paramref name="stream"/> is null.</exception>
-    public void SaveToBinaryStream(Stream stream, BinaryWriter writer)
+    public void SaveToBinaryStream(Stream stream, BinaryWriter? writer)
     {
       if (stream == null)
       {
@@ -580,15 +590,15 @@ void WriteSection(Section section)
     /// <exception cref="ArgumentNullException">When a null reference is set.</exception>
     public static CultureInfo CultureInfo
     {
-      get => s_cultureInfo;
+      get => s_cultureInfo!;
       set => s_cultureInfo = value ?? throw new ArgumentNullException(nameof(value));
     }
 
     /// <summary>
     /// Gets the array that contains all valid comment delimiting characters.
     /// The default value is { '#', ';' }.
     /// </summary>
-    public static HashSet<char> ValidCommentChars { get; private set; }
+    public static HashSet<char> ValidCommentChars { get; private set; } = null!;
 
     /// <summary>
     /// Gets or sets the preferred comment char when saving configurations.
@@ -603,7 +613,7 @@ public static char PreferredCommentChar
       {
         if (!ValidCommentChars.Contains(value))
         {
-          throw new ArgumentException("The specified char '" + value + "' is not allowed as a comment char.");
+          throw new ArgumentException($"The specified char '{value}' is not allowed as a comment char.");
         }
 
         s_preferredCommentChar = value;
@@ -749,7 +759,7 @@ public IEnumerable<Section> GetSectionsNamed(string name)
     }
 
     // Finds a section by its name.
-    private Section FindSection(string name)
+    private Section? FindSection(string name)
     {
       return _sections.FirstOrDefault(
           section => string.Equals(section.Name, name, StringComparison.OrdinalIgnoreCase));

Src/ConfigurationElement.cs

@@ -32,12 +32,12 @@ internal ConfigurationElement(string name)
     /// <summary>
     /// Gets or sets the comment of this element.
     /// </summary>
-    public string Comment { get; set; }
+    public string? Comment { get; set; }
 
     /// <summary>
     /// Gets the comment above this element.
     /// </summary>
-    public string PreComment { get; set; }
+    public string? PreComment { get; set; }
 
     /// <summary>
     /// Gets the string representation of the element.
@@ -74,9 +74,9 @@ public override string ToString()
     private string GetFormattedComment()
     {
       // Only get the first line of the inline comment.
-      var comment = Comment;
+      var comment = Comment!;
 
-      var newLineIndex = Comment.IndexOfAny(Environment.NewLine.ToCharArray());
+      var newLineIndex = comment.IndexOfAny(Environment.NewLine.ToCharArray());
       if (newLineIndex >= 0)
       {
         comment = comment.Substring(0, newLineIndex);
@@ -89,7 +89,7 @@ private string GetFormattedComment()
     // to be written to a config file.
     private string GetFormattedPreComment()
     {
-      var lines = PreComment.Split(formattedPreCommentSeparator, StringSplitOptions.None);
+      var lines = PreComment!.Split(formattedPreCommentSeparator, StringSplitOptions.None);
 
       return string.Join(
           Environment.NewLine, Array.ConvertAll(lines, s => Configuration.PreferredCommentChar + " " + s));

Src/ConfigurationReader.cs

@@ -26,7 +26,7 @@ private static void Parse(StringReader reader, Configuration config)
       var currentSection = new Section(Section.DefaultSectionName);
       var preCommentBuilder = new StringBuilder();
       var lineNumber = 0;
-      string line;
+      string? line;
 
       // Read until EOF.
       while ((line = reader.ReadLine()) != null)
@@ -82,7 +82,7 @@ private static void Parse(StringReader reader, Configuration config)
             currentSection.PreComment =
                 preCommentBuilder.ToString().TrimEnd(Environment.NewLine.ToCharArray());
 
-            preCommentBuilder.Length = 0; // Clear the SB - With .NET >= 4.0: preCommentBuilder.Clear()
+            preCommentBuilder.Clear();
           }
 
           config._sections.Add(currentSection);
@@ -109,7 +109,7 @@ private static void Parse(StringReader reader, Configuration config)
       }
     }
 
-    private static string ParseComment(string line, out int commentCharIndex)
+    private static string? ParseComment(string line, out int commentCharIndex)
     {
       // A comment starts with a valid comment character that:
       // 1. is not within a quote (eg. "this is # not a comment"), and
@@ -118,7 +118,7 @@ private static string ParseComment(string line, out int commentCharIndex)
       // A quote has two quotation marks, neither of which is escaped.
       // For example: "this is a quote \" with an escaped quotation mark inside of it"
 
-      string comment = null;
+      string? comment = null;
       commentCharIndex = -1;
 
       var index = 0;
@@ -191,7 +191,7 @@ private static Setting ParseSetting(string line, StringReader reader, ref int li
       // 2) "<name>" = <value>
       //      <name> may contain any char, including '='
 
-      string settingName = null;
+      string? settingName = null;
       int equalSignIndex;
 
       // Parse the name first.
@@ -247,18 +247,19 @@ private static Setting ParseSetting(string line, StringReader reader, ref int li
         settingValueBuffer.AppendLine("[[");
 
         bool foundClosing = false;
+        string? multilineLine;
 
-        while ((line = reader.ReadLine()) != null)
+        while ((multilineLine = reader.ReadLine()) != null)
         {
           ++lineNumber;
 
-          if (line == "]]")
+          if (multilineLine == "]]")
           {
             foundClosing = true;
             break;
           }
 
-          settingValueBuffer.AppendLine(line);
+          settingValueBuffer.AppendLine(multilineLine);
         }
 
         if (!foundClosing)
@@ -271,10 +272,10 @@ private static Setting ParseSetting(string line, StringReader reader, ref int li
         settingValue = settingValueBuffer.ToString();
       }
 
-      return new Setting(settingName, settingValue);
+      return new Setting(settingName!, settingValue);
     }
 
-    internal static Configuration ReadFromBinaryStream(Stream stream, BinaryReader reader)
+    internal static Configuration ReadFromBinaryStream(Stream stream, BinaryReader? reader)
     {
       if (stream == null)
       {

Src/ConfigurationWriter.cs

@@ -28,21 +28,21 @@ protected override void Dispose(bool disposing)
       }
     }
 
-    internal static void WriteToStreamTextual(Configuration cfg, Stream stream, Encoding encoding)
+    internal static void WriteToStreamTextual(Configuration cfg, Stream stream, Encoding? encoding)
     {
-      Debug.Assert(cfg != null);
+      if (cfg == null)
+      {
+        throw new ArgumentNullException(nameof(cfg));
+      }
 
       if (stream == null)
       {
         throw new ArgumentNullException(nameof(stream));
       }
 
-      if (encoding == null)
-      {
-        encoding = Encoding.UTF8;
-      }
+      encoding ??= Encoding.UTF8;
 
-      var str = cfg.SaveToString();
+      string str = cfg.SaveToString();
 
       // Encode & write the string.
       var byteBuffer = new byte[encoding.GetByteCount(str)];
@@ -52,9 +52,12 @@ internal static void WriteToStreamTextual(Configuration cfg, Stream stream, Enco
       stream.Flush();
     }
 
-    internal static void WriteToStreamBinary(Configuration cfg, Stream stream, BinaryWriter writer)
+    internal static void WriteToStreamBinary(Configuration cfg, Stream stream, BinaryWriter? writer)
     {
-      Debug.Assert(cfg != null);
+      if (cfg == null)
+      {
+        throw new ArgumentNullException(nameof(cfg));
+      }
 
       if (stream == null)
       {

Src/ITypeStringConverter.cs

@@ -21,7 +21,7 @@ public interface ITypeStringConverter
     /// <summary>
     /// The type that this converter is able to convert to and from a string.
     /// </summary>
-    Type ConvertibleType { get; }
+    Type? ConvertibleType { get; }
 
     /// <summary>
     /// Tries to convert a string value to an object of this converter's type.
@@ -34,7 +34,7 @@ public interface ITypeStringConverter
     ///     This parameter can be safely ignored for custom converters.
     /// </param>
     /// <returns>The converted object, or null if conversion is not possible.</returns>
-    object TryConvertFromString(string value, Type hint);
+    object? TryConvertFromString(string value, Type hint);
   }
 
   /// <summary>
@@ -67,6 +67,6 @@ public abstract class TypeStringConverter<T> : ITypeStringConverter
     ///     This parameter can be safely ignored for custom converters.
     /// </param>
     /// <returns>The converted object, or null if conversion is not possible.</returns>
-    public abstract object TryConvertFromString(string value, Type hint);
+    public abstract object? TryConvertFromString(string value, Type hint);
   }
 }