replace concurrentdictionary with generic instance creation

replace instance lambda with static
copied from JakeBayer#42

Author: ycherkes

FuzzySharp/PreProcess/StringPreprocessorFactory.cs

@@ -27,7 +27,7 @@ public static Func<string, string> GetPreprocessor(PreprocessMode mode)
             return mode switch
             {
                 PreprocessMode.Full => Default,
-                PreprocessMode.None => s => s,
+                PreprocessMode.None => static s => s,
                 _ => throw new InvalidOperationException($"Invalid string preprocessor mode: {mode}")
             };
         }

FuzzySharp/SimilarityRatio/ScorerCache.cs

@@ -1,15 +1,17 @@
-using System;
-using System.Collections.Concurrent;
+using System.Runtime.CompilerServices;
 using FuzzySharp.SimilarityRatio.Scorer;
 
 namespace FuzzySharp.SimilarityRatio
 {
     public static class ScorerCache
     {
-        private static readonly ConcurrentDictionary<Type, IRatioScorer> s_scorerCache = new ConcurrentDictionary<Type, IRatioScorer>();
-        public static IRatioScorer Get<T>() where T : IRatioScorer, new()
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static IRatioScorer Get<T>() where T : IRatioScorer, new() => GenericCache<T>.Instance;
+
+        private static class GenericCache<T>
+            where T : IRatioScorer, new()
         {
-            return s_scorerCache.GetOrAdd(typeof(T), new T());
+            public static readonly T Instance = new T();
         }
     }
-}
+}