.NETStandard 2.0 support

Author: julkiewicz

src/ECS.Boost/Friflo.Engine.ECS.Boost.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>library</OutputType>
-    <TargetFrameworks>net8.0;net7.0;net6.0;netstandard2.1</TargetFrameworks>
+    <TargetFrameworks>net8.0;net7.0;net6.0;netstandard2.1;netstandard2.0</TargetFrameworks>
     <ImplicitUsings>disable</ImplicitUsings>
     <Nullable>disable</Nullable>
     <RootNamespace>Friflo.Engine.ECS</RootNamespace>

src/ECS/Archetype/EntityStore.Archetype.cs

@@ -4,6 +4,7 @@
 // Hard rule: this file MUST NOT use type: Entity
 
 using System;
+using Friflo.Engine.ECS.Compat;
 
 // ReSharper disable InlineTemporaryVariable
 // ReSharper disable ArrangeTrailingCommaInMultilineLists

src/ECS/Base/SchemaUtils.cs

@@ -18,7 +18,11 @@ private static bool RegisterComponentTypesByReflection() {
         if (Platform.IsUnityRuntime) {
             return true;
         }
+#if NETSTANDARD && !NETSTANDARD2_1_OR_GREATER
+        return true;
+#else
         return System.Runtime.CompilerServices.RuntimeFeature.IsDynamicCodeCompiled;
+#endif
     }
 
     [ExcludeFromCodeCoverage]

src/ECS/Compat/HashSet.cs

@@ -0,0 +1,18 @@
+using System.Collections.Generic;
+
+namespace Friflo.Engine.ECS.Compat;
+
+#if NETSTANDARD && !NETSTANDARD2_1_OR_GREATER
+public static class HashSet
+{
+    public static bool TryGetValue<T>(this HashSet<T> set, T value, out T actualValue)
+    {
+        if (set.Contains(value)) {
+            actualValue = value;
+            return true;
+        }
+        actualValue = default;
+        return false;
+    }
+}
+#endif

src/ECS/Entity/MemberPath.cs

@@ -104,6 +104,10 @@ private MemberPath(MemberPathKey key, ComponentType componentType, int structInd
 
     private const BindingFlags Flags = BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.GetField | BindingFlags.GetProperty;
 
+#if NETSTANDARD && !NETSTANDARD2_1_OR_GREATER
+    private static readonly char[] SplitDotArray = ['.'];
+#endif
+    
     /// <summary>
     /// Returns a <see cref="MemberPath"/> identifying a specific field / property by its <paramref name="path"/>
     /// within the passed <paramref name="type"/>.
@@ -122,7 +126,11 @@ public static MemberPath Get(Type type, string path)
         if (Map.TryGetValue(key, out var componentFieldInfo)) {
             return componentFieldInfo;
         }
+#if NETSTANDARD && !NETSTANDARD2_1_OR_GREATER
+        var pathItems   = path.Split(SplitDotArray, StringSplitOptions.RemoveEmptyEntries);
+#else
         var pathItems   = path.Split('.', StringSplitOptions.RemoveEmptyEntries);
+#endif
         var memberInfos = new MemberInfo[pathItems.Length];
         var memberType  = type;
         bool canWrite   = true;
@@ -188,10 +196,24 @@ public static MemberPath Get(Type type, string path)
 
     // See ThrowIfTypeNeverValidGenericArgument() at:
     // https://github.com/dotnet/runtime/blob/4f5c6938d09e935830492c006aa8381611b65ad8/src/libraries/System.Private.CoreLib/src/System/RuntimeType.cs#L736
-    private static bool IsInvalidType(Type type) {
-        return  type.IsPointer || type.IsByRef || type == typeof(void) ||
-                type.IsByRefLike; // type is a ref struct. E.g. Span<>
+private static bool IsInvalidType(Type type)
+{
+    if (type.IsPointer || type.IsByRef || type == typeof(void))
+        return true;
+#if NETSTANDARD && !NETSTANDARD2_1_OR_GREATER
+    if (type.IsByRef)
+        return true;
+    if (type.IsGenericType)
+    {
+        var genericTypeDef = type.GetGenericTypeDefinition();
+        if (genericTypeDef == typeof(Span<>) || genericTypeDef == typeof(ReadOnlySpan<>))
+            return true;
     }
+    return false;
+#else
+    return type.IsByRefLike; // type is a ref struct. E.g. Span<>
+#endif
+}
 
     // ReSharper disable UnusedMember.Local
     [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2026", Justification = "Not called for NativeAOT")]

src/ECS/Friflo.Engine.ECS.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>library</OutputType>
-    <TargetFrameworks>net8.0;net7.0;net6.0;netstandard2.1</TargetFrameworks>
+    <TargetFrameworks>net8.0;net7.0;net6.0;netstandard2.1;netstandard2.0</TargetFrameworks>
     <ImplicitUsings>disable</ImplicitUsings>
     <Nullable>disable</Nullable>
     <RootNamespace>Friflo.Engine.ECS</RootNamespace>

src/ECS/Systems/Extensions/SystemPerf.cs

@@ -92,7 +92,11 @@ public PerfResource () {
 
     [ExcludeFromCodeCoverage]
     internal static long GetAllocatedBytes() {
+#if NETSTANDARD && !NETSTANDARD2_1_OR_GREATER
+        return 0; 
+#else
         return Platform.IsUnityRuntime ? 0 : GC.GetAllocatedBytesForCurrentThread(); 
+#endif
     }
 }
 

src/ECS/Utils/TreeUtils.cs

@@ -80,7 +80,12 @@ private static void DuplicateChildren(Entity entity, Entity clone, EntityStore s
     public static AddDataEntitiesResult AddDataEntitiesToEntity(Entity targetEntity, IReadOnlyList<DataEntity> dataEntities)
     {
         var entityCount     = dataEntities.Count;
+#if NETSTANDARD && !NETSTANDARD2_1_OR_GREATER
+        var childEntities   = new HashSet<long>         ();
+        childEntities.EnsureCapacity(entityCount);
+#else
         var childEntities   = new HashSet<long>         (entityCount);
+#endif
         var oldToNewPid     = new Dictionary<long, long>(entityCount);
         var newToOldPid     = new Dictionary<long, long>(entityCount);
         var store           = targetEntity.Store;

src/Hub/Engine.Hub.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>library</OutputType>
-    <TargetFrameworks>net8.0;netstandard2.1</TargetFrameworks>
+    <TargetFrameworks>net8.0;netstandard2.1;netstandard2.0</TargetFrameworks>
     <ImplicitUsings>disable</ImplicitUsings>
     <Nullable>disable</Nullable>
     <RootNamespace>Friflo.Engine.Hub</RootNamespace>

src/Tests-NativeAOT/Tests-NativeAOT.csproj

@@ -2,7 +2,6 @@
 
     <PropertyGroup>
         <OutputType>Exe</OutputType>
-        <PublishAot>true</PublishAot>
         <!-- <DefineConstants Condition="'$(PublishAot)' == 'true'">
             $(DefineConstants);IS_NATIVE_AOT
         </DefineConstants> -->