1 files changed, 60 insertions, 0 deletions
diff --git a/src/System.Private.CoreLib/src/System/AppContextSwitches.cs b/src/System.Private.CoreLib/src/System/AppContextSwitches.cs
new file mode 100644
index 000000000..f838871e8
--- /dev/null
+++ b/src/System.Private.CoreLib/src/System/AppContextSwitches.cs
@@ -0,0 +1,60 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Runtime.CompilerServices;
+
+namespace System
+{
+    internal static class AppContextSwitches
+    {
+        private static int _enforceJapaneseEraYearRanges;
+        public static bool EnforceJapaneseEraYearRanges
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            get
+            {
+                return GetCachedSwitchValue("Switch.System.Globalization.EnforceJapaneseEraYearRanges", ref _enforceJapaneseEraYearRanges);
+            }
+        }
+
+        //
+        // Implementation details
+        //
+
+        private static bool DisableCaching { get; set; }
+
+        static AppContextSwitches()
+        {
+            bool isEnabled;
+            if (AppContext.TryGetSwitch(@"TestSwitch.LocalAppContext.DisableCaching", out isEnabled))
+            {
+                DisableCaching = isEnabled;
+            }
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        internal static bool GetCachedSwitchValue(string switchName, ref int switchValue)
+        {
+            if (switchValue < 0) return false;
+            if (switchValue > 0) return true;
+
+            return GetCachedSwitchValueInternal(switchName, ref switchValue);
+        }
+
+        private static bool GetCachedSwitchValueInternal(string switchName, ref int switchValue)
+        {
+            bool isSwitchEnabled;
+            AppContext.TryGetSwitch(switchName, out isSwitchEnabled);
+
+            if (DisableCaching)
+            {
+                return isSwitchEnabled;
+            }
+
+            switchValue = isSwitchEnabled ? 1 /*true*/ : -1 /*false*/;
+            return isSwitchEnabled;
+        }
+    }
+}