search char equivalences unicode

Robust.Client/UserInterface/Controllers/Implementations/EntitySpawningUIController.cs

@@ -241,17 +241,17 @@ private static bool DoesEntityMatchSearch(EntityPrototype prototype, string sear
         if (string.IsNullOrEmpty(searchStr))
             return true;
 
-        if (prototype.ID.Contains(searchStr, StringComparison.InvariantCultureIgnoreCase))
+        if (prototype.ID.ContainsSearch(searchStr))
             return true;
 
         if (prototype.EditorSuffix != null &&
-            prototype.EditorSuffix.Contains(searchStr, StringComparison.InvariantCultureIgnoreCase))
+            prototype.EditorSuffix.ContainsSearch(searchStr))
             return true;
 
         if (string.IsNullOrEmpty(prototype.Name))
             return false;
 
-        if (prototype.Name.Contains(searchStr, StringComparison.InvariantCultureIgnoreCase))
+        if (prototype.Name.ContainsSearch(searchStr))
             return true;
 
         return false;

Robust.Client/UserInterface/Controllers/Implementations/TileSpawningUIController.cs

@@ -221,8 +221,8 @@ private void BuildTileList(string? searchStr = null)
         if (!string.IsNullOrEmpty(searchStr))
         {
             tileDefs = tileDefs.Where(s =>
-                Loc.GetString(s.Name).Contains(searchStr, StringComparison.CurrentCultureIgnoreCase) ||
-                s.ID.Contains(searchStr, StringComparison.OrdinalIgnoreCase));
+                Loc.GetString(s.Name).ContainsSearch(searchStr) ||
+                s.ID.ContainsSearch(searchStr));
         }
 
         tileDefs = tileDefs.OrderBy(d => Loc.GetString(d.Name));

Robust.Shared/Utility/SearchHelpers.cs

@@ -0,0 +1,41 @@
+using System.Globalization;
+
+namespace Robust.Shared.Utility;
+
+/// <summary>
+///     Helpers for user-facing text search that use Unicode-aware comparison, so that characters
+///     differing only by diacritical marks are treated as equivalent.
+/// </summary>
+/// <remarks>
+///     Uses <see cref="CompareOptions.IgnoreNonSpace"/>, <see cref="CompareOptions.IgnoreWidth"/>,
+///     and <see cref="CompareOptions.IgnoreKanaType"/> via <see cref="CompareInfo"/>. This means:
+///     <list type="bullet">
+///       <item>Characters that differ only by diacritical marks are equivalent: Russian ё matches е,
+///       German ü matches u, French é/è/ê all match e, Spanish ñ matches n, etc.</item>
+///       <item>Full-width and half-width variants of the same character are equivalent (relevant for
+///       Japanese and Chinese input).</item>
+///       <item>Hiragana and Katakana representations of the same sound are equivalent.</item>
+///     </list>
+///     Uses the current culture so that locale-specific comparison rules are respected.
+///     No configuration or setup is required; any UI code can call <see cref="ContainsSearch"/> directly.
+/// </remarks>
+public static class SearchHelpers
+{
+    private const CompareOptions SearchOptions =
+        CompareOptions.IgnoreCase |
+        CompareOptions.IgnoreNonSpace |
+        CompareOptions.IgnoreWidth |
+        CompareOptions.IgnoreKanaType;
+
+    /// <summary>
+    ///     Returns <see langword="true"/> if <paramref name="source"/> contains
+    ///     <paramref name="search"/>, ignoring case, diacritical marks, character width, and
+    ///     kana type.
+    /// </summary>
+    public static bool ContainsSearch(this string source, string search)
+    {
+        if (string.IsNullOrEmpty(search)) return true;
+        if (string.IsNullOrEmpty(source)) return false;
+        return CultureInfo.CurrentCulture.CompareInfo.IndexOf(source, search, SearchOptions) >= 0;
+    }
+}