Adapt the code and project structure to easuly build with Unity

.gitignore

@@ -32,3 +32,5 @@ BenchmarkDotNet.Artifacts
 
 /YamlDotNet.AotTest/exitcode.txt
 /tools/build/Properties/launchSettings.json
+/YamlDotNet.Unity
+*.meta

YamlDotNet/Core/ParserExtensions.cs

@@ -129,13 +129,15 @@ public static T Expect<T>(this IParser parser) where T : ParsingEvent
         }
 
         [Obsolete("Please use TryConsume<T>(out var evt) instead")]
-        public static T? Allow<T>(this IParser parser) where T : ParsingEvent
+        [return: MaybeNull]
+        public static T Allow<T>(this IParser parser) where T : ParsingEvent
         {
             return parser.TryConsume<T>(out var @event) ? @event : default;
         }
 
         [Obsolete("Please use Accept<T>(out var evt) instead")]
-        public static T? Peek<T>(this IParser parser) where T : ParsingEvent
+        [return: MaybeNull]
+        public static T Peek<T>(this IParser parser) where T : ParsingEvent
         {
             return parser.Accept<T>(out var @event) ? @event : default;
         }

YamlDotNet/Helpers/ExpressionExtensions.cs

@@ -22,6 +22,7 @@
 #if !NET20
 
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq.Expressions;
 using System.Reflection;
 
@@ -47,7 +48,8 @@ public static PropertyInfo AsProperty(this LambdaExpression propertyAccessor)
             return property;
         }
 
-        private static TMemberInfo? TryGetMemberExpression<TMemberInfo>(LambdaExpression lambdaExpression)
+        [return: MaybeNull]
+        private static TMemberInfo TryGetMemberExpression<TMemberInfo>(LambdaExpression lambdaExpression)
             where TMemberInfo : MemberInfo
         {
             if (lambdaExpression.Parameters.Count != 1)

YamlDotNet/Helpers/Portability/readme.txt → YamlDotNet/Portability/readme.txt

@@ -1,11 +1,12 @@
 The subdirectories of this directory contain platform-specific code
 that aims to bridge the gap between the different targetted platforms.
 
-Each directory sould contain code that should only be included
+Each directory should contain code that should only be included or excluded
 on a set of platforms. The name of the directory should consist of a list
 of target platforms, separated by a plus sign (+).
-Optionally, a sub-directory named 'others' may be added. Its contents will be
-included in all other target platforms.
+In that directory, every file inside the 'include' subdirectory
+will be included in those platforms, while every file inside the 'exclude' subdirectory
+will be included in all other platforms.
 
 Most (all?) types added to this folder should be internal to avoid conflicting
 with other libraries.

YamlDotNet/Serialization/Utilities/TypeConverter.cs

@@ -247,7 +247,7 @@ partial class TypeConverter
         /// </summary>
         /// <typeparam name="TConvertible">The type to which the converter should be associated.</typeparam>
         /// <typeparam name="TConverter">The type of the converter.</typeparam>
-#if !(NETCOREAPP3_1 || NETSTANDARD2_1 || NETSTANDARD1_3 || UNITY)
+#if NET20 || NET35 || NET45
         [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.LinkDemand, Name = "FullTrust")]
 #endif
         public static void RegisterTypeConverter<TConvertible, TConverter>()

YamlDotNet/Serialization/YamlAttributeOverrides.cs

@@ -21,6 +21,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using HashCode = YamlDotNet.Core.HashCode;
 
@@ -107,7 +108,8 @@ public int Matches(Type matchType)
 
         private readonly Dictionary<AttributeKey, List<AttributeMapping>> overrides = new Dictionary<AttributeKey, List<AttributeMapping>>();
 
-        public T? GetAttribute<T>(Type type, string member) where T : Attribute
+        [return: MaybeNull]
+        public T GetAttribute<T>(Type type, string member) where T : Attribute
         {
             if (overrides.TryGetValue(new AttributeKey(typeof(T), member), out var mappings))
             {

YamlDotNet/YamlDotNet.csproj

@@ -37,11 +37,11 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <None Include="Helpers/Portability/**/*.cs" />
-    <Compile Remove="Helpers/Portability/**/*.cs" />
-    <Compile Include="Helpers/Portability/*$(RealTargetFramework)*/*.cs" />
-    <Compile Include="Helpers/Portability/*/others/*.cs" />
-    <Compile Remove="Helpers/Portability/*$(RealTargetFramework)*/others/*.cs" />
+    <None Include="Portability/**/*.cs" />
+    <Compile Remove="Portability/**/*.cs" />
+    <Compile Include="Portability/*$(RealTargetFramework)*/include/*.cs" />
+    <Compile Include="Portability/*/exclude/*.cs" />
+    <Compile Remove="Portability/*$(RealTargetFramework)*/exclude/*.cs" />
   </ItemGroup>
 
   <ItemGroup>