thomasgalliker · thomasgalliker · Jan 13, 2026 · Dec 5, 2025 · Dec 5, 2025 · Dec 5, 2025
diff --git a/.editorconfig b/.editorconfig
@@ -1,7 +1,7 @@
 ####################################################################
-# Editor Configuration (Updated 2023-07-26)
+# Editor Configuration (Updated 2025-12-05)
 #
-# (c)2023 superdev GmbH
+# (c)2025 superdev GmbH
 ####################################################################
 
 root = true
@@ -15,7 +15,7 @@ tab_width = 2
 indent_style = space
 indent_size = 4
 tab_width = 4
-end_of_line = crlf
+end_of_line = lf
 trim_trailing_whitespace = true
 insert_final_newline = false
 max_line_length = 200
@@ -112,6 +112,7 @@ dotnet_style_prefer_inferred_tuple_names = true:suggestion
 dotnet_style_prefer_inferred_anonymous_type_member_names = true:suggestion
 dotnet_style_prefer_compound_assignment = true:suggestion
 dotnet_style_prefer_simplified_interpolation = true:suggestion
+dotnet_style_prefer_collection_expression = false:silent
 dotnet_style_namespace_match_folder = true:suggestion
 dotnet_style_operator_placement_when_wrapping = beginning_of_line
 csharp_style_unused_value_expression_statement_preference = discard_variable:none
@@ -175,4 +176,7 @@ dotnet_diagnostic.IDE0051.severity = warning
 dotnet_diagnostic.CS1591.severity = none
 
 # CA1416: Validate platform compatibility
-dotnet_diagnostic.CA1416.severity = suggestion
+dotnet_diagnostic.CA1416.severity = suggestion
+
+# LocalVariableHidesMember: Local variable hides member
+resharper_local_variable_hides_member_highlighting = none
diff --git a/Diacritics.sln.DotSettings b/Diacritics.sln.DotSettings
@@ -0,0 +1,7 @@
+<wpf:ResourceDictionary xml:space="preserve" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:s="clr-namespace:System;assembly=mscorlib" xmlns:ss="urn:shemas-jetbrains-com:settings-storage-xaml" xmlns:wpf="http://schemas.microsoft.com/winfx/2006/xaml/presentation">
+	<s:Boolean x:Key="/Default/UserDictionary/Words/=Aerzte/@EntryIndexedValue">True</s:Boolean>
+	<s:Boolean x:Key="/Default/UserDictionary/Words/=Delemont/@EntryIndexedValue">True</s:Boolean>
+	<s:Boolean x:Key="/Default/UserDictionary/Words/=Del_00E9mont/@EntryIndexedValue">True</s:Boolean>
+	<s:Boolean x:Key="/Default/UserDictionary/Words/=Gefaess/@EntryIndexedValue">True</s:Boolean>
+	<s:Boolean x:Key="/Default/UserDictionary/Words/=Gef_00E4_00DF/@EntryIndexedValue">True</s:Boolean>
+	<s:Boolean x:Key="/Default/UserDictionary/Words/=_00C4rzte/@EntryIndexedValue">True</s:Boolean></wpf:ResourceDictionary>
diff --git a/Diacritics/Diacritics.csproj b/Diacritics/Diacritics.csproj
@@ -1,9 +1,11 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net462;netstandard1.2;netstandard2.0;netstandard2.1;net7.0;net8.0;net9.0</TargetFrameworks>
+    <TargetFrameworks>net48;netstandard1.2;netstandard2.0;netstandard2.1;net7.0;net8.0;net9.0</TargetFrameworks>
     <OutputType>Library</OutputType>
     <SignAssembly>True</SignAssembly>
+    <LangVersion>latest</LangVersion>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
 
   <!--NuGet package-->
@@ -28,7 +30,6 @@
     <SymbolPackageFormat>snupkg</SymbolPackageFormat>
     <EmbedAllSources>true</EmbedAllSources>
     <PublishRepositoryUrl>true</PublishRepositoryUrl>
-    <SignAssembly>True</SignAssembly>
   </PropertyGroup>
 
   <ItemGroup>
@@ -40,7 +41,6 @@
   <PropertyGroup Condition=" '$(Configuration)' == 'Release' ">
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
   </PropertyGroup>
-
 
   <ItemGroup Condition=" '$(TargetFramework)' == 'net462' ">
     <Reference Include="System" />

diff --git a/Diacritics/DiacriticsMapper.cs b/Diacritics/DiacriticsMapper.cs
@@ -1,19 +1,20 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
-using System.Linq;
-using System.Text;
+using System.Diagnostics.CodeAnalysis;
 using System.Threading;
 using Diacritics.AccentMappings;
 using Diacritics.Internals;
 
+// ReSharper disable ConvertIfStatementToNullCoalescingAssignment
+
 namespace Diacritics
 {
     public class DiacriticsMapper : IDiacriticsMapper
     {
         #region DiacriticsMapper.Current
 
-        private static Lazy<IDiacriticsMapper> Implementation;
+        private static Lazy<IDiacriticsMapper> Implementation = null!;
 
         static DiacriticsMapper()
         {
@@ -43,35 +44,37 @@ public DiacriticsMapper(params IAccentMapping[] mappings)
 
         private static IDictionary<char, MappingReplacement> ConvertMappings(IAccentMapping[] accentMappings)
         {
+            if (accentMappings == null)
+            {
+                throw new ArgumentNullException(nameof(accentMappings));
+            }
+
             var all = new Dictionary<char, MappingReplacement>();
 
-            if (accentMappings != null)
+            foreach (var accentMapping in accentMappings)
             {
-                foreach (var accentMapping in accentMappings)
+                var mappings = accentMapping.Mapping;
+                foreach (var mapping in mappings)
                 {
-                    var mappings = accentMapping.Mapping;
-                    foreach (var mapping in mappings)
+                    if (!all.TryGetValue(mapping.Key, out var mappingReplacement))
                     {
-                        if (!all.TryGetValue(mapping.Key, out var mappingReplacement))
+                        all[mapping.Key] = mapping.Value;
+                    }
+                    else
+                    {
+                        // Merge existing DecomposeTitle and Decompose properties,
+                        // unless the current mapping replacement defines them.
+                        if (mappingReplacement.DecomposeTitle == null)
                         {
-                            all[mapping.Key] = mapping.Value;
+                            mappingReplacement.DecomposeTitle = mapping.Value.DecomposeTitle;
                         }
-                        else
+
+                        if (mappingReplacement.Decompose == null)
                         {
-                            // Merge existing DecomposeTitle and Decompose properties,
-                            // unless the current mapping replacement defines them.
-                            if (mappingReplacement.DecomposeTitle == null)
-                            {
-                                mappingReplacement.DecomposeTitle = mapping.Value.DecomposeTitle;
-                            }
-
-                            if (mappingReplacement.Decompose == null)
-                            {
-                                mappingReplacement.Decompose = mapping.Value.Decompose;
-                            }
-
-                            all[mapping.Key] = mappingReplacement;
+                            mappingReplacement.Decompose = mapping.Value.Decompose;
                         }
+
+                        all[mapping.Key] = mappingReplacement;
                     }
                 }
             }
@@ -90,28 +93,33 @@ IEnumerator IEnumerable.GetEnumerator()
             return this.GetEnumerator();
         }
 
-        public string RemoveDiacritics(string source)
+        [return: NotNullIfNotNull(nameof(source))]
+        public string? RemoveDiacritics(string? source)
         {
             return this.RemoveDiacritics(source, options: null);
         }
 
-        public string RemoveDiacritics(string source, DiacriticsOptions options)
+        [return: NotNullIfNotNull(nameof(source))]
+        public string? RemoveDiacritics(string? source, DiacriticsOptions? options)
         {
             return RemoveDiacritics(source, this.diacriticsMappings, options);
         }
 
-        public string RemoveDiacritics(string source, IAccentMapping[] mappings)
+        [return: NotNullIfNotNull(nameof(source))]
+        public string? RemoveDiacritics(string? source, IAccentMapping[] mappings)
         {
             return this.RemoveDiacritics(source, mappings, options: null);
         }
 
-        public string RemoveDiacritics(string source, IAccentMapping[] mappings, DiacriticsOptions options)
+        [return: NotNullIfNotNull(nameof(source))]
+        public string? RemoveDiacritics(string? source, IAccentMapping[] mappings, DiacriticsOptions? options)
         {
             var diacriticsMappings = ConvertMappings(mappings);
             return RemoveDiacritics(source, diacriticsMappings, options);
         }
 
-        private static string RemoveDiacritics(string source, IDictionary<char, MappingReplacement> diacriticsMappings, DiacriticsOptions options)
+        [return: NotNullIfNotNull(nameof(source))]
+        private static string? RemoveDiacritics(string? source, IDictionary<char, MappingReplacement> diacriticsMappings, DiacriticsOptions? options)
         {
             if (string.IsNullOrWhiteSpace(source))
             {
@@ -120,18 +128,17 @@ private static string RemoveDiacritics(string source, IDictionary<char, MappingR
 
             var decompose = options?.Decompose ?? false;
 
-            var result = StringBuilderCache.Acquire(source.Length);
+            // ReSharper disable once RedundantSuppressNullableWarningExpression
+            var result = StringBuilderCache.Acquire(source!.Length);
 
             for (var currentIndex = 0; currentIndex < source.Length; currentIndex++)
             {
                 var currentChar = source[currentIndex];
 
                 if (diacriticsMappings.TryGetValue(currentChar, out var mappingReplacement))
                 {
-                    var replacement = (decompose ? currentIndex == 0 ?
-                        mappingReplacement.DecomposeTitle ?? mappingReplacement.Decompose :
-                        mappingReplacement.Decompose :
-                        mappingReplacement.Base) ?? mappingReplacement.Base;
+                    var replacement = (decompose ? currentIndex == 0 ? mappingReplacement.DecomposeTitle ?? mappingReplacement.Decompose : mappingReplacement.Decompose : mappingReplacement.Base) ??
+                                      mappingReplacement.Base;
 
                     result.Append(replacement);
                 }
@@ -144,12 +151,12 @@ private static string RemoveDiacritics(string source, IDictionary<char, MappingR
             return StringBuilderCache.GetStringAndRelease(result);
         }
 
-        public bool HasDiacritics(string source)
+        public bool HasDiacritics(string? source)
         {
             return this.HasDiacritics(source, options: null);
         }
 
-        public bool HasDiacritics(string source, DiacriticsOptions options)
+        public bool HasDiacritics(string? source, DiacriticsOptions? options)
         {
             return source != this.RemoveDiacritics(source, options);
         }

diff --git a/Diacritics/Extensions/StringExtensions.cs b/Diacritics/Extensions/StringExtensions.cs
@@ -1,42 +1,47 @@
 
+using System.Diagnostics.CodeAnalysis;
 using Diacritics.AccentMappings;
 
 namespace Diacritics.Extensions
 {
     public static class StringExtensions
     {
         /// <inheritdoc cref="IDiacriticsMapper.RemoveDiacritics(string)"/>
-        public static string RemoveDiacritics(this string source)
+        [return: NotNullIfNotNull(nameof(source))]
+        public static string? RemoveDiacritics(this string? source)
         {
             return DiacriticsMapper.Current.RemoveDiacritics(source);
         }
 
         /// <inheritdoc cref="IDiacriticsMapper.RemoveDiacritics(string, DiacriticsOptions)"/>
-        public static string RemoveDiacritics(this string source, DiacriticsOptions options)
+        [return: NotNullIfNotNull(nameof(source))]
+        public static string? RemoveDiacritics(this string? source, DiacriticsOptions options)
         {
             return DiacriticsMapper.Current.RemoveDiacritics(source, options);
         }
 
         /// <inheritdoc cref="IDiacriticsMapper.RemoveDiacritics(string, IAccentMapping[])"/>
-        public static string RemoveDiacritics(this string source, params IAccentMapping[] mappings)
+        [return: NotNullIfNotNull(nameof(source))]
+        public static string? RemoveDiacritics(this string? source, params IAccentMapping[] mappings)
         {
             return DiacriticsMapper.Current.RemoveDiacritics(source, mappings);
         }
 
         /// <inheritdoc cref="IDiacriticsMapper.RemoveDiacritics(string, IAccentMapping[], DiacriticsOptions)"/>
-        public static string RemoveDiacritics(this string source, IAccentMapping[] mappings, DiacriticsOptions options)
+        [return: NotNullIfNotNull(nameof(source))]
+        public static string? RemoveDiacritics(this string? source, IAccentMapping[] mappings, DiacriticsOptions options)
         {
             return DiacriticsMapper.Current.RemoveDiacritics(source, mappings, options);
         }
 
         /// <inheritdoc cref="IDiacriticsMapper.HasDiacritics(string)"/>
-        public static bool HasDiacritics(this string source)
+        public static bool HasDiacritics(this string? source)
         {
             return DiacriticsMapper.Current.HasDiacritics(source);
         }
 
         /// <inheritdoc cref="IDiacriticsMapper.HasDiacritics(string, DiacriticsOptions)"/>
-        public static bool HasDiacritics(this string source, DiacriticsOptions options)
+        public static bool HasDiacritics(this string? source, DiacriticsOptions options)
         {
             return DiacriticsMapper.Current.HasDiacritics(source, options);
         }

diff --git a/Diacritics/IDiacriticsMapper.cs b/Diacritics/IDiacriticsMapper.cs
@@ -16,43 +16,43 @@ public interface IDiacriticsMapper : IEnumerable<KeyValuePair<char, MappingRepla
         /// Removes any diacritical characters from <paramref name="source"/>.
         /// </summary>
         /// <param name="source">The source string.</param>
-        string RemoveDiacritics(string source);
+        string? RemoveDiacritics(string? source);
 
         /// <summary>
         /// Removes any diacritical characters from <paramref name="source"/>.
         /// </summary>
         /// <param name="source">The source string.</param>
         /// <param name="options">The options.</param>
-        string RemoveDiacritics(string source, DiacriticsOptions options);
+        string? RemoveDiacritics(string? source, DiacriticsOptions? options);
 
         /// <summary>
         /// Removes any diacritical characters from <paramref name="source"/> using custom accent mappings.
         /// </summary>
         /// <param name="source">The source string.</param>
         /// <param name="mappings">The accent mapping to be used to replace diacritical characters.</param>
-        string RemoveDiacritics(string source, IAccentMapping[] mappings);
+        string? RemoveDiacritics(string? source, IAccentMapping[] mappings);
 
         /// <summary>
         /// Removes any diacritical characters from <paramref name="source"/> using custom accent mappings.
         /// </summary>
         /// <param name="source">The source string.</param>
         /// <param name="mappings">The accent mapping to be used to replace diacritical characters.</param>
         /// <param name="options">The options.</param>
-        string RemoveDiacritics(string source, IAccentMapping[] mappings, DiacriticsOptions options);
+        string? RemoveDiacritics(string? source, IAccentMapping[] mappings, DiacriticsOptions? options);
 
         /// <summary>
         /// Checks if the given <paramref name="source"/> string contains any diacritical characters.
         /// </summary>
         /// <param name="source">The source string.</param>
         /// <returns><c>true</c> if the source string contains any diacritical characters; otherwise, <c>false</c>.</returns>
-        bool HasDiacritics(string source);
+        bool HasDiacritics(string? source);
 
         /// <summary>
         /// Checks if the given <paramref name="source"/> string contains any diacritical characters.
         /// </summary>
         /// <param name="source">The source string.</param>
         /// <param name="options">The options.</param>
         /// <returns><c>true</c> if the source string contains any diacritical characters; otherwise, <c>false</c>.</returns>
-        bool HasDiacritics(string source, DiacriticsOptions options);
+        bool HasDiacritics(string? source, DiacriticsOptions? options);
     }
 }