Brondahl EnumStringValues EnumExtensions.cs GetStringValuesWithPreferences_Uncache resource consumption

@@ -269,15 +269,12 @@ private static bool TryParseStringValueToEnum_ViaCache<TEnumType>(string lowerSt
     {

       var enumTypeObject = typeof(TEnumType);

 

-      var typeAppropriateDictionary = parsedEnumStringsDictionaryByType.GetOrAdd(enumTypeObject, (x) => new ConcurrentDictionary<string, Enum>());

+      var typeAppropriateDictionary = parsedEnumStringsDictionaryByType.GetOrAdd(

+        enumTypeObject, 

+        (x) => BuildCacheDictionaryForParseStringValue<TEnumType>()

+      );

 

-      var cachedValue = typeAppropriateDictionary.GetOrAdd(lowerStringValue, (str) =>

-      {

-        var parseSucceededForDictionary = TryParseStringValueToEnum_Uncached<TEnumType>(lowerStringValue, out var parsedValueForDictionary);

-        return parseSucceededForDictionary ? (Enum) parsedValueForDictionary : null;

-      });

-

-      if (cachedValue != null)

+      if (typeAppropriateDictionary.TryGetValue(lowerStringValue, out var cachedValue))

       {

         parsedValue = (TEnumType)cachedValue;

         return true;

@@ -292,6 +289,25 @@ private static bool TryParseStringValueToEnum_ViaCache<TEnumType>(string lowerSt
     /// <summary> Cache for <see cref="TryParseStringValueToEnum{TEnumType}"/> </summary>

     private static ConcurrentDictionary<Type, ConcurrentDictionary<string, Enum>> parsedEnumStringsDictionaryByType;

 

+

+    private static ConcurrentDictionary<string, Enum> BuildCacheDictionaryForParseStringValue<TEnumType>() where TEnumType : System.Enum

+    {

+      var dict = new ConcurrentDictionary<string, Enum>();

+

+      foreach (var enumValue in EnumerateValues<TEnumType>())

+      {

+        foreach (var enumString in GetStringValues<TEnumType>(enumValue))

+        {

+            // Add to the dictionary, just overwriting if the string is already present.

+            // This overwrite is legitimate, because we've declared parsing a duplicate string definition to be `undefined behaviour`.

+            dict.AddOrUpdate(enumString.ToLower(), enumValue, ((repeatedString, previousEnumValue) => enumValue));

+        }

+      }

+

+      return dict;

+    }

+

+

     private static bool TryParseStringValueToEnum_Uncached<TEnumType>(this string lowerStringValue, out TEnumType parsedValue) where TEnumType : System.Enum

     {

       foreach (var enumValue in EnumerateValues<TEnumType>())