Unstable 1.8.4.0

Libraries/BarotraumaLibs/BarotraumaCore/Extensions/EnumExtensions.cs

@@ -1,17 +1,27 @@
 using System;
+using System.Collections.Generic;
+
+// NOTE: We should use struct in addition to Enum in all the type constraints (at the end of the method signatures), as it
+// tells the compiler that we're only ever using value types, which enums always are anyway.
+// This avoids a lot of allocations caused by the compiler preparing for anything, which in turn happens because despite
+// how it works in practice, Enum is counted as a reference type in C#... for historical reasons.
+
+// We use the (int)(object) cast because generic types can't be cast directly to int, so we box into object and unbox into int instead.
+// It avoids some memory allocations that Convert.ToInt32() seems to do.
+// NOTE: This should work fine as long as the enum values stay within - to + 2^31, so let's not use uint or long for them.
 
 namespace Barotrauma.Extensions
 {
     public static class EnumExtensions
     {
         /// <summary>
-        /// Enum.HasFlag() checks if all flags matches. This method checks if any of them matches.
+        /// Enum.HasFlag() checks if all flags matches. This method checks if any of them matches. It also avoids boxing allocations that the built-in version might still sometimes cause.
         /// E.g. when myEnum = SomeEnum.First | SomeEnum.Second, myEnum.HasFlag(SomeEnum.First | SomeEnum.Third) returns false, because not all of the flags match, but HasAnyFlag(SomeEnum.First | SomeEnum.Third) returns true, because some of the flags match.
         /// </summary>
-        public static bool HasAnyFlag<T>(this T type, T value) where T : Enum
+        public static bool HasAnyFlag<T>(this T type, T value) where T : struct, Enum
         {
-            int typeValue = Convert.ToInt32(type);
-            int flagValue = Convert.ToInt32(value);
+            int typeValue = (int)(object)type;
+            int flagValue = (int)(object)value;
             return (typeValue & flagValue) != 0;
         }
 
@@ -19,10 +29,10 @@ namespace Barotrauma.Extensions
         /// Adds a flag value to an enum.
         /// Note that enums are value types, so you need to use the value returned from this method.
         /// </summary>
-        public static T AddFlag<T>(this T @enum, T flag) where T : Enum
+        public static T AddFlag<T>(this T @enum, T flag) where T : struct, Enum
         {
-            int enumValue = Convert.ToInt32(@enum);
-            int flagValue = Convert.ToInt32(flag);
+            int enumValue = (int)(object)@enum;
+            int flagValue = (int)(object)flag;
             return (T)(object)(enumValue | flagValue);
         }
 
@@ -30,11 +40,19 @@ namespace Barotrauma.Extensions
         /// Removes a flag value from an enum.
         /// Note that enums are value types, so you need to use the value returned from this method.
         /// </summary>
-        public static T RemoveFlag<T>(this T @enum, T flag) where T : Enum
+        public static T RemoveFlag<T>(this T @enum, T flag) where T : struct, Enum
         {
-            int enumValue = Convert.ToInt32(@enum);
-            int flagValue = Convert.ToInt32(flag);
+            int enumValue = (int)(object)@enum;
+            int flagValue = (int)(object)flag;
             return (T)(object)(enumValue & ~flagValue);
         }
+
+        public static IEnumerable<T> GetIndividualFlags<T>(T flagsEnum) where T : struct, Enum
+        {
+            foreach (T value in Enum.GetValues(typeof(T)))
+            {
+                if (flagsEnum.HasAnyFlag(value)) { yield return value; }
+            }
+        }
     }
 }