Bump version

Bumps [actions/setup-dotnet](https://github.com/actions/setup-dotnet) from 4.0.1 to 4.1.0.
- [Release notes](https://github.com/actions/setup-dotnet/releases)
- [Commits](https://github.com/actions/setup-dotnet/compare/v4.0.1...v4.1.0)

---
updated-dependencies:
- dependency-name: actions/setup-dotnet
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/dotnet.yml

@@ -7,14 +7,31 @@ on:
     branches: [ master ]
 
 jobs:
+  net8:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v4
+    - name: Setup .NET
+      uses: actions/[email protected]
+      with:
+        dotnet-version: 8.0.x
+    - name: Restore dependencies
+      run: dotnet restore
+    - name: Build
+      run: dotnet build --framework net8.0 --no-restore
+    - name: Test
+      run: dotnet test --framework net8.0 --no-build --verbosity normal
+
   net7:
 
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Setup .NET
-      uses: actions/setup-dotnet@v3.2.0
+      uses: actions/setup-dotnet@v4.1.0
       with:
         dotnet-version: 7.0.x
     - name: Restore dependencies
@@ -29,9 +46,9 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Setup .NET
-      uses: actions/setup-dotnet@v3.2.0
+      uses: actions/setup-dotnet@v4.1.0
       with:
         dotnet-version: 6.0.x
     - name: Restore dependencies
@@ -46,13 +63,11 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Setup .NET
-      uses: actions/setup-dotnet@v3.2.0
+      uses: actions/setup-dotnet@v4.1.0
       with:
-        dotnet-version: | 
-            5.0.x
-            6.0.x
+        dotnet-version: 5.0.x
     - name: Restore dependencies
       run: dotnet restore
     - name: Build

AssetRipper.Primitives.Tests/AssetRipper.Primitives.Tests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
 	<PropertyGroup>
-		<TargetFrameworks>netframework3.5;netframework4.0;netframework4.8;net5.0;net6.0;net7.0</TargetFrameworks>
+		<TargetFrameworks>net35;net40;net48;net5.0;net6.0;net7.0;net8.0</TargetFrameworks>
 		<LangVersion>Latest</LangVersion>
 		<Nullable>enable</Nullable>
 
@@ -9,14 +9,14 @@
 	</PropertyGroup>
 
 	<ItemGroup>
-		<PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.6.3" />
-		<PackageReference Include="NUnit" Version="3.13.3" />
+		<PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.9.0" />
+		<PackageReference Include="NUnit" Version="3.14.0" />
 		<PackageReference Include="NUnit3TestAdapter" Version="4.5.0" />
-		<PackageReference Include="NUnit.Analyzers" Version="3.6.1">
+		<PackageReference Include="NUnit.Analyzers" Version="4.1.0">
 			<PrivateAssets>all</PrivateAssets>
 			<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
 		</PackageReference>
-		<PackageReference Include="coverlet.collector" Version="6.0.0" />
+		<PackageReference Include="coverlet.collector" Version="6.0.2" />
 	</ItemGroup>
 
 	<ItemGroup>

AssetRipper.Primitives.Tests/ComparisonTests.cs

@@ -68,8 +68,8 @@ public class ComparisonTests
 	{
 		Assert.Multiple(() =>
 		{
-			Assert.That(new UnityVersion(2019, 1, 0, UnityVersionType.Final, 1).IsGreaterEqual(2019, 1, 0), Is.True);
-			Assert.That(new UnityVersion(2019, 1, 0, UnityVersionType.Final, 1).IsLessEqual(2019, 1, 0), Is.True);
+			Assert.That(new UnityVersion(2019, 1, 0, UnityVersionType.Final, 1).GreaterThanOrEquals(2019, 1, 0));
+			Assert.That(new UnityVersion(2019, 1, 0, UnityVersionType.Final, 1).LessThanOrEquals(2019, 1, 0));
 		});
 	}
 }

AssetRipper.Primitives.Tests/ParsingTests.cs

@@ -6,22 +6,28 @@ namespace AssetRipper.Primitives.Tests;
 public class ParsingTests
 {
 	[TestCase("4.2.2f1", 4, 2, 2, UnityVersionType.Final, 1, null, "Normal Unity 4 Version")]
-	[TestCase("4.2.2f1\n1", 4, 2, 2, UnityVersionType.Final, 1, 1, "Custom Unity 4 Version")]
+	[TestCase("4.2.2f1\n1", 4, 2, 2, UnityVersionType.Final, 1, "\n1", "Custom Unity 4 Version")]
 	[TestCase("2343.4.5f7", 2343, 4, 5, UnityVersionType.Final, 7, null, "Fictitious Future Version")]
-	[TestCase("2019.2.2f1c2\n2", 2019, 2, 2, UnityVersionType.China, 2, 2, "Fake Custom Chinese Version")]
+	[TestCase("2019.2.2f1c2\n2", 2019, 2, 2, UnityVersionType.China, 2, "\n2", "Fake Custom Chinese Version")]
+	[TestCase("2019", 2019, 0, 0, UnityVersionType.Final, 1, null, "Major Only")]
 	[TestCase("2019.4", 2019, 4, 0, UnityVersionType.Final, 1, null, "Major Minor Only")]
 	[TestCase("2019.4.3", 2019, 4, 3, UnityVersionType.Final, 1, null, "Major Minor Build Only")]
-	public void UnityVersionParsesCorrectly(string versionString, int major, int minor, int build, UnityVersionType type, int typeNumber, int? customEngine, string name)
+	[TestCase("0", 0, 0, 0, UnityVersionType.Alpha, 0, null, "Zero, Major Only")]
+	[TestCase("0.0", 0, 0, 0, UnityVersionType.Alpha, 0, null, "Zero, Major Minor Only")]
+	[TestCase("0.0.0", 0, 0, 0, UnityVersionType.Alpha, 0, null, "Zero, Major Minor Build Only")]
+	[TestCase("0.0.0b2", 0, 0, 0, UnityVersionType.Beta, 2, null, "Zero, Full")]
+	[TestCase("2019.2.2f1-letters", 2019, 2, 2, UnityVersionType.Final, 1, "-letters", "Issue #40 - Appended Custom Characters")]
+	public void UnityVersionParsesCorrectly(string versionString, int major, int minor, int build, UnityVersionType type, int typeNumber, string? customEngine, string name)
 	{
 		UnityVersion expected = new UnityVersion((ushort)major, (ushort)minor, (ushort)build, type, (byte)typeNumber);
-		UnityVersion parsedVersion = UnityVersion.Parse(versionString, out int? parsedCustomEngine);
+		UnityVersion parsedVersion = UnityVersion.Parse(versionString, out string? parsedCustomEngine);
 		Assert.Multiple(() =>
 		{
 			Assert.That(parsedCustomEngine, Is.EqualTo(customEngine), $"The custom engine boolean is incorrect for '{name}'");
 			Assert.That(parsedVersion, Is.EqualTo(expected), $"The parsed version is incorrect for '{name}'");
-			if (customEngine is not null || typeNumber is not 1)
+			if (customEngine is not null || typeNumber is not 0 and not 1)
 			{
-				Assert.That(parsedVersion.ToString(UnityVersionFormatFlags.Default, parsedCustomEngine), Is.EqualTo(versionString));
+				Assert.That(parsedVersion.ToString(UnityVersionFormatFlags.Default, parsedCustomEngine ?? ""), Is.EqualTo(versionString));
 			}
 		});
 	}
@@ -30,7 +36,7 @@ public class ParsingTests
 	public void UnityVersionToStringParsesCorrectly(UnityVersion version)
 	{
 		string versionString = version.ToString();
-		UnityVersion parsedVersion = UnityVersion.Parse(versionString, out int? customEngine);
+		UnityVersion parsedVersion = UnityVersion.Parse(versionString, out string? customEngine);
 		Assert.Multiple(() =>
 		{
 			Assert.That(customEngine, Is.Null);
@@ -67,6 +73,22 @@ public class ParsingTests
 		});
 	}
 
+	[TestCase("g2019")]
+	[TestCase("g2019.4")]
+	[TestCase("g2019.4.3")]
+	[TestCase("g2019.4.3f")]
+	[TestCase("g2019.4.3f1")]
+	[TestCase("g2019.4.3f1c1")]
+	[TestCase("2019g")]
+	[TestCase("2019.4g")]
+	[TestCase("2019.4.3g")]
+	[TestCase("2019.4.3fg")]
+	// "2019.4.3f1g" and "2019.4.3f1c1g" are technically valid because custom engines often append some text to the version string.
+	public void InvalidVersionStringFailsToParse(string versionString)
+	{
+		Assert.That(UnityVersion.TryParse(versionString, out _, out _), Is.False);
+	}
+
 	private static IEnumerable<UnityVersion> GenerateRandomVersions(int count)
 	{
 		Randomizer random = TestContext.CurrentContext.Random;

AssetRipper.Primitives.Tests/UnityGuidTests.cs

@@ -1,4 +1,4 @@
-#if NET7_0_OR_GREATER
+#if NET5_0_OR_GREATER
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 
@@ -83,7 +83,7 @@ public class UnityGuidTests
 	{
 		Guid originalGuid = Guid.NewGuid();
 		UnityGuid tobyteArrayGuid = new UnityGuid(originalGuid.ToByteArray());
-		UnityGuid memoryMarshallGuid = new UnityGuid(MemoryMarshal.Cast<Guid, byte>(new ReadOnlySpan<Guid>(in originalGuid)));
+		UnityGuid memoryMarshallGuid = Unsafe.As<Guid, UnityGuid>(ref originalGuid);
 		Assert.That(memoryMarshallGuid, Is.EqualTo(tobyteArrayGuid));
 	}
 }

AssetRipper.Primitives.Tests/Utf8StringTests.cs

@@ -1,8 +1,17 @@
-#if NET7_0_OR_GREATER
+#if NET5_0_OR_GREATER
 namespace AssetRipper.Primitives.Tests;
 
 public class Utf8StringTests
 {
+	[Test]
+	public void Utf8StringEqualityWorks()
+	{
+		Utf8String utf8Str = new Utf8String("AssetRipperTestString");
+		Utf8String utf8Str2 = new Utf8String(utf8Str.Data.ToArray());
+
+		Assert.That(utf8Str2, Is.EqualTo(utf8Str));
+	}
+
 	[Test]
 	public void StringEmptyIsEquivalentToUtf8StringEmpty()
 	{
@@ -28,5 +37,51 @@ public class Utf8StringTests
 		Utf8String systemString = "AssetRipperTestString";
 		Assert.That(dataString, Is.EqualTo(systemString));
 	}
+
+	[Test]
+	public void ConcatenationBetweenTwoUtf8StringsWorks()
+	{
+		Utf8String dataString = "AssetRipperTestString"u8;
+		Utf8String systemString = "AssetRipperTestString";
+		Utf8String concatenated = dataString + systemString;
+		Assert.That(concatenated, Is.EqualTo((Utf8String)"AssetRipperTestStringAssetRipperTestString"u8));
+	}
+
+	[Test]
+	public void ConcatenationBetweenThreeUtf8StringsWorksTheSameAsAddition()
+	{
+		Utf8String added = "String1"u8 + new Utf8String("2") + "3"u8;
+		Utf8String concatenated = Utf8String.Concat("String1"u8, "2"u8, "3"u8);
+		Assert.That(added, Is.EqualTo(concatenated));
+	}
+
+	[Test]
+	public void ConcatenationBetweenFourUtf8StringsWorks()
+	{
+		Utf8String string1 = "hello"u8;
+		Utf8String string2 = " world"u8;
+		Utf8String string3 = "!"u8;
+		Utf8String string4 = ", how are you?"u8;
+		Utf8String concatenated = Utf8String.Concat(string1, string2, string3, string4);
+		Assert.That(concatenated, Is.EqualTo((Utf8String)"hello world!, how are you?"u8));
+	}
+
+	[Test]
+	public void IsNullOrEmptyReturnsTrueForEmptyString()
+	{
+		Assert.That(Utf8String.IsNullOrEmpty(Utf8String.Empty), Is.True);
+	}
+
+	[Test]
+	public void IsNullOrEmptyReturnsTrueForNullString()
+	{
+		Assert.That(Utf8String.IsNullOrEmpty(null), Is.True);
+	}
+
+	[Test]
+	public void IsNullOrEmptyReturnsFalseForNonEmptyString()
+	{
+		Assert.That(Utf8String.IsNullOrEmpty("AssetRipperTestString"u8), Is.False);
+	}
 }
 #endif

AssetRipper.Primitives/AssetRipper.Primitives.csproj

@@ -1,12 +1,12 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
 	<PropertyGroup>
-		<TargetFrameworks>netframework3.5;netframework4.0;netstandard2.0;net5.0;net6.0;net7.0</TargetFrameworks>
+		<TargetFrameworks>net35;net40;net461;netstandard2.0;net5.0;net6.0;net7.0;net8.0</TargetFrameworks>
 		<LangVersion>Latest</LangVersion>
 		<Nullable>enable</Nullable>
 		<Authors>ds5678</Authors>
 		<Company>AssetRipper</Company>
-		<Version>2.0.0.0</Version>
+		<Version>3.1.4</Version>
 		<AssemblyVersion>$(Version)</AssemblyVersion>
 		<PackageId>AssetRipper.Primitives</PackageId>
 		<PackageTags>C# assetripper unity unity3d</PackageTags>
@@ -14,26 +14,45 @@
 		<PackageLicenseExpression>MIT</PackageLicenseExpression>
 		<RepositoryType>git</RepositoryType>
 		<PackageProjectUrl>https://github.com/AssetRipper/AssetRipper.Primitives</PackageProjectUrl>
-		<Copyright>Copyright (c) 2022-2023 ds5678</Copyright>
+		<Copyright>Copyright (c) 2022-2024 ds5678</Copyright>
 		<Description>Managed library for primitive types used in AssetRipper.</Description>
 		<GeneratePackageOnBuild>true</GeneratePackageOnBuild>
 		<GenerateDocumentationFile>true</GenerateDocumentationFile>
 		<NoWarn>1591</NoWarn>
 	</PropertyGroup>
 	
-	<PropertyGroup Condition=" '$(TargetFramework)' != 'netframework3.5' and '$(TargetFramework)' != 'netframework4.0' ">
+	<PropertyGroup Condition=" '$(TargetFramework)' != 'net35' and '$(TargetFramework)' != 'net40' ">
 		<IsTrimmable>true</IsTrimmable>
 	</PropertyGroup>
 
+	<PropertyGroup Condition=" '$(TargetFramework)' == 'net8.0' ">
+		<IsAotCompatible>true</IsAotCompatible>
+	</PropertyGroup>
+
 	<ItemGroup>
-		<PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.1.1">
+		<PackageReference Include="Microsoft.SourceLink.GitHub" Version="8.0.0">
 			<PrivateAssets>all</PrivateAssets>
 			<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
 		</PackageReference>
-		<PackageReference Include="PolySharp" Version="1.13.2">
+		<PackageReference Include="PolySharp" Version="1.14.1">
 			<PrivateAssets>all</PrivateAssets>
 			<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
 		</PackageReference>
 	</ItemGroup>
 
+	<ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0' or '$(TargetFramework)' == 'net461'">
+		<PackageReference Include="Microsoft.Bcl.HashCode">
+			<Version>1.1.1</Version>
+		</PackageReference>
+		<PackageReference Include="System.Memory">
+			<Version>4.5.5</Version>
+		</PackageReference>
+	</ItemGroup>
+
+	<ItemGroup Condition="'$(TargetFramework)' == 'net461'">
+		<PackageReference Include="System.ValueTuple">
+			<Version>4.5.0</Version>
+		</PackageReference>
+	</ItemGroup>
+
 </Project>

AssetRipper.Primitives/UnityGuid.cs

@@ -1,21 +1,31 @@
-#if NET7_0_OR_GREATER
+#if NET5_0_OR_GREATER || NETSTANDARD2_0_OR_GREATER || NET461_OR_GREATER
 using System.Buffers.Binary;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
+using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using System.Security.Cryptography;
 using System.Text;
-using System.Text.Json.Serialization;
 
 namespace AssetRipper.Primitives;
 
-[JsonConverter(typeof(UnityGuidJsonConverter))]
+#if NET5_0_OR_GREATER
+[System.Text.Json.Serialization.JsonConverter(typeof(UnityGuidJsonConverter))]
+#endif
 public readonly record struct UnityGuid
+#if NET7_0_OR_GREATER
+	: System.Numerics.IEqualityOperators<UnityGuid, UnityGuid, bool>
+#endif
 {
 	public UnityGuid(Guid guid)
 	{
+#if NET5_0_OR_GREATER
 		Span<byte> guidData = stackalloc byte[16];
 		bool success = guid.TryWriteBytes(guidData);
 		Debug.Assert(success);
+#else
+		Span<byte> guidData = guid.ToByteArray();
+#endif
 		ConvertSystemOrUnityBytes(guidData, guidData);
 		Data0 = ReadUInt32LittleEndian(guidData, 0);
 		Data1 = ReadUInt32LittleEndian(guidData, 1);
@@ -44,10 +54,24 @@ public readonly record struct UnityGuid
 		//This is not an acceptable way to convert between Unity and System Guids.
 		//We only do it this way to efficiently get 16 random bytes.
 		//We don't care about official Guid validity because Unity does not care either.
-		Guid guid = Guid.NewGuid();
-		ReadOnlySpan<Guid> guidSpan = new ReadOnlySpan<Guid>(in guid);
-		ReadOnlySpan<byte> byteSpan = MemoryMarshal.AsBytes(guidSpan);
-		return new UnityGuid(byteSpan);
+		if (Unsafe.SizeOf<Guid>() == Unsafe.SizeOf<UnityGuid>())
+		{
+			Guid guid = Guid.NewGuid();
+			return Unsafe.As<Guid, UnityGuid>(ref guid);
+		}
+		else
+		{
+			return ThrowOrReturnDefault();
+		}
+
+		static UnityGuid ThrowOrReturnDefault()
+		{
+#if DEBUG
+			throw new InvalidCastException($"{nameof(UnityGuid)} struct size does not match {nameof(Guid)}.");
+#else
+			return default;
+#endif
+		}
 	}
 
 	public static explicit operator UnityGuid(Guid systemGuid) => new UnityGuid(systemGuid);
@@ -57,7 +81,11 @@ public readonly record struct UnityGuid
 		Span<byte> span = stackalloc byte[16];
 		unityGuid.Write(span);
 		ConvertSystemOrUnityBytes(span, span);
+#if NET5_0_OR_GREATER
 		return new Guid(span);
+#else
+		return new Guid(span.ToArray());
+#endif
 	}
 
 	private void Write(Span<byte> span)
@@ -77,7 +105,23 @@ public readonly record struct UnityGuid
 
 	public override string ToString()
 	{
-		Span<char> span = stackalloc char[32]
+		Span<char> span = stackalloc char[32];
+		ToString(span);
+		return CreateString(span);
+
+		static string CreateString(Span<char> span)
+		{
+#if NET5_0_OR_GREATER
+			return new string(span);
+#else
+			return new string(span.ToArray());
+#endif
+		}
+	}
+
+	public void ToString(Span<char> buffer)
+	{
+		ReadOnlySpan<char> span = stackalloc char[32]
 		{
 			GetHexChar(Data0, 0),
 			GetHexChar(Data0, 4),
@@ -113,7 +157,7 @@ public readonly record struct UnityGuid
 			GetHexChar(Data3, 28),
 		};
 
-		return new string(span);
+		span.CopyTo(buffer);
 
 		static char GetHexChar(uint value, int offset)
 		{
@@ -186,15 +230,31 @@ public readonly record struct UnityGuid
 	/// <returns>A stable guid corresponding to the <paramref name="input"/>.</returns>
 	public static UnityGuid Md5Hash(scoped ReadOnlySpan<byte> input)
 	{
-		byte[] hashBytes = MD5.HashData(input);
-		ConvertSystemOrUnityBytes(hashBytes, hashBytes);
-		return new UnityGuid(hashBytes);
+		Span<byte> buffer = stackalloc byte[16];
+		HashData(input, buffer);
+		ConvertSystemOrUnityBytes(buffer, buffer);
+		return new UnityGuid(buffer);
+	}
+
+	private static void HashData(ReadOnlySpan<byte> data, Span<byte> buffer)
+	{
+#if NET5_0_OR_GREATER
+		MD5.HashData(data, buffer);
+#else
+		MD5.Create().ComputeHash(data.ToArray()).AsSpan().CopyTo(buffer);
+#endif
 	}
 
 	public static UnityGuid Md5Hash(scoped ReadOnlySpan<byte> assemblyName, scoped ReadOnlySpan<byte> @namespace, scoped ReadOnlySpan<byte> className)
 	{
 		int length = assemblyName.Length + @namespace.Length + className.Length;
-		Span<byte> input = length < 1024 ? stackalloc byte[length] : GC.AllocateUninitializedArray<byte>(length);
+		Span<byte> input = length < 1024
+			? stackalloc byte[length]
+#if NET5_0_OR_GREATER
+			: GC.AllocateUninitializedArray<byte>(length);
+#else
+			: new byte[length];
+#endif
 		assemblyName.CopyTo(input);
 		@namespace.CopyTo(input.Slice(assemblyName.Length));
 		className.CopyTo(input.Slice(assemblyName.Length + @namespace.Length));

AssetRipper.Primitives/UnityGuidJsonConverter.cs

@@ -1,4 +1,4 @@
-#if NET7_0_OR_GREATER
+#if NET5_0_OR_GREATER
 using System.Text.Json;
 using System.Text.Json.Serialization;
 

AssetRipper.Primitives/UnityVersion.ComparisonMethods.cs

@@ -6,41 +6,41 @@ public readonly partial struct UnityVersion
 	private const ulong subMinorMask = 0x00000000FFFFFFFFUL;
 	private const ulong subBuildMask = 0x000000000000FFFFUL;
 	private const ulong subTypeMask = 0x00000000000000FFUL;
-#pragma warning disable CS1591 // Missing XML comment for publicly visible type or member
-	public bool IsEqual(ushort major) => this == From(major);
-	public bool IsEqual(ushort major, ushort minor) => this == From(major, minor);
-	public bool IsEqual(ushort major, ushort minor, ushort build) => this == From(major, minor, build);
-	public bool IsEqual(ushort major, ushort minor, ushort build, UnityVersionType type) => this == From(major, minor, build, type);
-	public bool IsEqual(ushort major, ushort minor, ushort build, UnityVersionType type, byte typeNumber) => this == new UnityVersion(major, minor, build, type, typeNumber);
-	public bool IsEqual(string version) => this == Parse(version);
 
-	public bool IsLess(ushort major) => this < From(major);
-	public bool IsLess(ushort major, ushort minor) => this < From(major, minor);
-	public bool IsLess(ushort major, ushort minor, ushort build) => this < From(major, minor, build);
-	public bool IsLess(ushort major, ushort minor, ushort build, UnityVersionType type) => this < From(major, minor, build, type);
-	public bool IsLess(ushort major, ushort minor, ushort build, UnityVersionType type, byte typeNumber) => this < new UnityVersion(major, minor, build, type, typeNumber);
-	public bool IsLess(string version) => this < Parse(version);
+	public bool Equals(ushort major) => this == From(major);
+	public bool Equals(ushort major, ushort minor) => this == From(major, minor);
+	public bool Equals(ushort major, ushort minor, ushort build) => this == From(major, minor, build);
+	public bool Equals(ushort major, ushort minor, ushort build, UnityVersionType type) => this == From(major, minor, build, type);
+	public bool Equals(ushort major, ushort minor, ushort build, UnityVersionType type, byte typeNumber) => this == new UnityVersion(major, minor, build, type, typeNumber);
+	public bool Equals(string version) => this == Parse(version);
 
-	public bool IsLessEqual(ushort major) => this <= From(major);
-	public bool IsLessEqual(ushort major, ushort minor) => this <= From(major, minor);
-	public bool IsLessEqual(ushort major, ushort minor, ushort build) => this <= From(major, minor, build);
-	public bool IsLessEqual(ushort major, ushort minor, ushort build, UnityVersionType type) => this <= From(major, minor, build, type);
-	public bool IsLessEqual(ushort major, ushort minor, ushort build, UnityVersionType type, byte typeNumber) => this <= new UnityVersion(major, minor, build, type, typeNumber);
-	public bool IsLessEqual(string version) => this <= Parse(version);
+	public bool LessThan(ushort major) => this < From(major);
+	public bool LessThan(ushort major, ushort minor) => this < From(major, minor);
+	public bool LessThan(ushort major, ushort minor, ushort build) => this < From(major, minor, build);
+	public bool LessThan(ushort major, ushort minor, ushort build, UnityVersionType type) => this < From(major, minor, build, type);
+	public bool LessThan(ushort major, ushort minor, ushort build, UnityVersionType type, byte typeNumber) => this < new UnityVersion(major, minor, build, type, typeNumber);
+	public bool LessThan(string version) => this < Parse(version);
 
-	public bool IsGreater(ushort major) => this > From(major);
-	public bool IsGreater(ushort major, ushort minor) => this > From(major, minor);
-	public bool IsGreater(ushort major, ushort minor, ushort build) => this > From(major, minor, build);
-	public bool IsGreater(ushort major, ushort minor, ushort build, UnityVersionType type) => this > From(major, minor, build, type);
-	public bool IsGreater(ushort major, ushort minor, ushort build, UnityVersionType type, byte typeNumber) => this > new UnityVersion(major, minor, build, type, typeNumber);
-	public bool IsGreater(string version) => this > Parse(version);
+	public bool LessThanOrEquals(ushort major) => this <= From(major);
+	public bool LessThanOrEquals(ushort major, ushort minor) => this <= From(major, minor);
+	public bool LessThanOrEquals(ushort major, ushort minor, ushort build) => this <= From(major, minor, build);
+	public bool LessThanOrEquals(ushort major, ushort minor, ushort build, UnityVersionType type) => this <= From(major, minor, build, type);
+	public bool LessThanOrEquals(ushort major, ushort minor, ushort build, UnityVersionType type, byte typeNumber) => this <= new UnityVersion(major, minor, build, type, typeNumber);
+	public bool LessThanOrEquals(string version) => this <= Parse(version);
 
-	public bool IsGreaterEqual(ushort major) => this >= From(major);
-	public bool IsGreaterEqual(ushort major, ushort minor) => this >= From(major, minor);
-	public bool IsGreaterEqual(ushort major, ushort minor, ushort build) => this >= From(major, minor, build);
-	public bool IsGreaterEqual(ushort major, ushort minor, ushort build, UnityVersionType type) => this >= From(major, minor, build, type);
-	public bool IsGreaterEqual(ushort major, ushort minor, ushort build, UnityVersionType type, byte typeNumber) => this >= new UnityVersion(major, minor, build, type, typeNumber);
-	public bool IsGreaterEqual(string version) => this >= Parse(version);
+	public bool GreaterThan(ushort major) => this > From(major);
+	public bool GreaterThan(ushort major, ushort minor) => this > From(major, minor);
+	public bool GreaterThan(ushort major, ushort minor, ushort build) => this > From(major, minor, build);
+	public bool GreaterThan(ushort major, ushort minor, ushort build, UnityVersionType type) => this > From(major, minor, build, type);
+	public bool GreaterThan(ushort major, ushort minor, ushort build, UnityVersionType type, byte typeNumber) => this > new UnityVersion(major, minor, build, type, typeNumber);
+	public bool GreaterThan(string version) => this > Parse(version);
+
+	public bool GreaterThanOrEquals(ushort major) => this >= From(major);
+	public bool GreaterThanOrEquals(ushort major, ushort minor) => this >= From(major, minor);
+	public bool GreaterThanOrEquals(ushort major, ushort minor, ushort build) => this >= From(major, minor, build);
+	public bool GreaterThanOrEquals(ushort major, ushort minor, ushort build, UnityVersionType type) => this >= From(major, minor, build, type);
+	public bool GreaterThanOrEquals(ushort major, ushort minor, ushort build, UnityVersionType type, byte typeNumber) => this >= new UnityVersion(major, minor, build, type, typeNumber);
+	public bool GreaterThanOrEquals(string version) => this >= Parse(version);
 	
 	private UnityVersion From(ushort major)
 	{
@@ -64,5 +64,4 @@ public readonly partial struct UnityVersion
 			((ulong)(ushort)type << typeOffset) | subTypeMask & m_data;
 		return new UnityVersion(data);
 	}
-#pragma warning restore CS1591 // Missing XML comment for publicly visible type or member
 }

AssetRipper.Primitives/UnityVersion.Interfaces.cs

@@ -27,12 +27,7 @@ public readonly partial struct UnityVersion : IEquatable<UnityVersion>, ICompara
 	/// </returns>
 	public int CompareTo(UnityVersion other)
 	{
-		if (this > other)
-			return 1;
-		else if (this < other)
-			return -1;
-		else
-			return 0;
+		return m_data.CompareTo(other.m_data);
 	}
 
 	/// <summary>
@@ -55,6 +50,6 @@ public readonly partial struct UnityVersion : IEquatable<UnityVersion>, ICompara
 	/// <inheritdoc/>
 	public override int GetHashCode()
 	{
-		return unchecked(827 + 911 * m_data.GetHashCode());
+		return m_data.GetHashCode();
 	}
 }

AssetRipper.Primitives/UnityVersion.Parsing.cs

@@ -2,14 +2,8 @@
 using System.Text.RegularExpressions;
 
 namespace AssetRipper.Primitives;
-
 public readonly partial struct UnityVersion
 {
-	private static readonly Regex majorMinorRegex = new Regex(@"^([0-9]+)\.([0-9]+)$", RegexOptions.Compiled);
-	private static readonly Regex majorMinorBuildRegex = new Regex(@"^([0-9]+)\.([0-9]+)\.([0-9]+)$", RegexOptions.Compiled);
-	private static readonly Regex normalRegex = new Regex(@"^([0-9]+)\.([0-9]+)\.([0-9]+)\.?([abcfpx])([0-9]+)(\n[0-9]+)?$", RegexOptions.Compiled);
-	private static readonly Regex chinaRegex = new Regex(@"^([0-9]+)\.([0-9]+)\.([0-9]+)\.?f1c([0-9]+)(\n[0-9]+)?$", RegexOptions.Compiled);
-	
 	/// <summary>
 	/// Serialize the version as a string using <see cref="UnityVersionFormatFlags.Default"/>.
 	/// </summary>
@@ -34,17 +28,22 @@ public readonly partial struct UnityVersion
 	/// Serialize the version as a string
 	/// </summary>
 	/// <param name="flags">The flags to control how the version is formatted</param>
-	/// <param name="customEngineNumber">The custom engine number to be appended</param>
+	/// <param name="customEngineString">The custom engine string to be appended</param>
 	/// <returns>A new string containing the formatted version.</returns>
-	public string ToString(UnityVersionFormatFlags flags, int? customEngineNumber)
+	public string ToString(UnityVersionFormatFlags flags,
+#if !NET6_0_OR_GREATER
+		string customEngineString = "")
+#else
+		ReadOnlySpan<char> customEngineString = default)
+#endif
 	{
-		return customEngineNumber is null
+		return customEngineString.Length == 0
 			? ToString(flags)
 			: (flags & UnityVersionFormatFlags.ExcludeType) != 0
 				? ToStringWithoutType()
 				: Type is not UnityVersionType.China || (flags & UnityVersionFormatFlags.UseShortChineseFormat) != 0
-					? $"{Major}.{Minor}.{Build}{Type.ToCharacter()}{TypeNumber}\n{customEngineNumber}"
-					: $"{Major}.{Minor}.{Build}f1c{TypeNumber}\n{customEngineNumber}";
+					? $"{Major}.{Minor}.{Build}{Type.ToCharacter()}{TypeNumber}{customEngineString}"
+					: $"{Major}.{Minor}.{Build}f1c{TypeNumber}{customEngineString}";
 	}
 
 	/// <summary>
@@ -59,66 +58,98 @@ public readonly partial struct UnityVersion
 	/// <summary>
 	/// Parse a normal Unity version string
 	/// </summary>
-	/// <param name="version">A string to parse</param>
+	/// <param name="s">A string to parse</param>
 	/// <returns>The parsed Unity version</returns>
-	/// <exception cref="ArgumentNullException">If the string is null or empty</exception>
 	/// <exception cref="ArgumentException">If the string is in an invalid format</exception>
-	public static UnityVersion Parse(string version) => Parse(version, out _);
+	public static UnityVersion Parse(string s) => Parse(s, out _);
 
 	/// <summary>
 	/// Parse a normal Unity version string
 	/// </summary>
-	/// <param name="version">A string to parse</param>
-	/// <param name="customEngine">True if this version was generated by a custom Unity Engine.</param>
+	/// <param name="s">A string to parse</param>
+	/// <param name="customEngine">Not null if this version was generated by a custom Unity Engine.</param>
 	/// <returns>The parsed Unity version</returns>
-	/// <exception cref="ArgumentNullException">If the string is null or empty</exception>
 	/// <exception cref="ArgumentException">If the string is in an invalid format</exception>
-	public static UnityVersion Parse(string version, out int? customEngine)
+	public static UnityVersion Parse(string s, out string? customEngine)
 	{
-		if (string.IsNullOrEmpty(version))
-		{
-			throw new ArgumentNullException(nameof(version));
-		}
+		return TryParse(s, out UnityVersion version, out customEngine)
+			? version
+			: throw new ArgumentException($"Invalid version format: {s}", nameof(s));
+	}
 
-		if (normalRegex.TryMatch(version, out Match? match))
+	/// <summary>
+	/// Try to parse a normal Unity version string
+	/// </summary>
+	/// <param name="s">A string to parse</param>
+	/// <param name="version">The parsed Unity version</param>
+	/// <param name="customEngine">Not null if this version was generated by a custom Unity Engine.</param>
+	/// <returns>True if parsing was successful</returns>
+	public static bool TryParse(string s, out UnityVersion version, out string? customEngine)
+	{
+		if (string.IsNullOrEmpty(s))
+		{
+			customEngine = null;
+			version = default;
+			return false;
+		}
+		else if (UnityVersionRegexes.GetChinaRegex().TryMatch(s, out Match? match))
+		{
+			int major = int.Parse(match.Groups[1].Value);
+			int minor = int.Parse(match.Groups[2].Value);
+			int build = int.Parse(match.Groups[3].Value);
+			int typeNumber = int.Parse(match.Groups[4].Value);
+			customEngine = GetNullableString(match.Groups[5]);
+			version = new UnityVersion((ushort)major, (ushort)minor, (ushort)build, UnityVersionType.China, (byte)typeNumber);
+			return true;
+		}
+		else if(UnityVersionRegexes.GetNormalRegex().TryMatch(s, out match))
 		{
 			int major = int.Parse(match.Groups[1].Value);
 			int minor = int.Parse(match.Groups[2].Value);
 			int build = int.Parse(match.Groups[3].Value);
 			char type = match.Groups[4].Value[0];
 			int typeNumber = int.Parse(match.Groups[5].Value);
-			customEngine = ParseNullableInteger(match.Groups[6]);
-			return new UnityVersion((ushort)major, (ushort)minor, (ushort)build, type.ToUnityVersionType(), (byte)typeNumber);
+			customEngine = GetNullableString(match.Groups[6]);
+			version = new UnityVersion((ushort)major, (ushort)minor, (ushort)build, type.ToUnityVersionType(), (byte)typeNumber);
+			return true;
 		}
-		else if (majorMinorBuildRegex.TryMatch(version, out match))
+		else if (UnityVersionRegexes.GetMajorMinorBuildRegex().TryMatch(s, out match))
 		{
 			int major = int.Parse(match.Groups[1].Value);
 			int minor = int.Parse(match.Groups[2].Value);
 			int build = int.Parse(match.Groups[3].Value);
 			customEngine = null;
-			return new UnityVersion((ushort)major, (ushort)minor, (ushort)build, UnityVersionType.Final, 1);
+			version = major is not 0 || minor is not 0 || build is not 0
+				? new UnityVersion((ushort)major, (ushort)minor, (ushort)build, UnityVersionType.Final, 1)
+				: default;
+			return true;
 		}
-		else if (majorMinorRegex.TryMatch(version, out match))
+		else if (UnityVersionRegexes.GetMajorMinorRegex().TryMatch(s, out match))
 		{
 			int major = int.Parse(match.Groups[1].Value);
 			int minor = int.Parse(match.Groups[2].Value);
 			customEngine = null;
-			return new UnityVersion((ushort)major, (ushort)minor, 0, UnityVersionType.Final, 1);
+			version = major is not 0 || minor is not 0
+				? new UnityVersion((ushort)major, (ushort)minor, 0, UnityVersionType.Final, 1)
+				: default;
+			return true;
 		}
-		else if (chinaRegex.TryMatch(version, out match))
+		else if (UnityVersionRegexes.GetMajorRegex().TryMatch(s, out match))
 		{
 			int major = int.Parse(match.Groups[1].Value);
-			int minor = int.Parse(match.Groups[2].Value);
-			int build = int.Parse(match.Groups[3].Value);
-			int typeNumber = int.Parse(match.Groups[4].Value);
-			customEngine = ParseNullableInteger(match.Groups[5]);
-			return new UnityVersion((ushort)major, (ushort)minor, (ushort)build, UnityVersionType.China, (byte)typeNumber);
+			customEngine = null;
+			version = major is not 0
+				? new UnityVersion((ushort)major, 0, 0, UnityVersionType.Final, 1)
+				: default;
+			return true;
 		}
 		else
 		{
-			throw new ArgumentException($"Invalid version format: {version}", nameof(version));
+			customEngine = null;
+			version = default;
+			return false;
 		}
 
-		static int? ParseNullableInteger(Capture capture) => capture.Length == 0 ? null : int.Parse(capture.Value);
+		static string? GetNullableString(Capture capture) => capture.Length == 0 ? null : capture.Value;
 	}
 }

AssetRipper.Primitives/UnityVersionRegexes.cs

@@ -0,0 +1,68 @@
+using System.Diagnostics.CodeAnalysis;
+using System.Text.RegularExpressions;
+
+namespace AssetRipper.Primitives;
+
+internal static partial class UnityVersionRegexes
+{
+#if NET35
+	private const RegexOptions Options = RegexOptions.None;
+#else
+	private const RegexOptions Options = RegexOptions.Compiled;
+#endif
+
+	[StringSyntax("regex")]
+	private const string Major = @"^([0-9]+)$";
+
+	[StringSyntax("regex")]
+	private const string MajorMinor = @"^([0-9]+)\.([0-9]+)$";
+
+	[StringSyntax("regex")]
+	private const string MajorMinorBuild = @"^([0-9]+)\.([0-9]+)\.([0-9]+)$";
+
+	[StringSyntax("regex")]
+	private const string Normal = @"^([0-9]+)\.([0-9]+)\.([0-9]+)\.?([abcfpx])([0-9]+)((?:.|[\r\n])+)?$";
+
+	[StringSyntax("regex")]
+	private const string China = @"^([0-9]+)\.([0-9]+)\.([0-9]+)\.?f1c([0-9]+)((?:.|[\r\n])+)?$";
+
+#if NET7_0_OR_GREATER
+	[GeneratedRegex(Major, Options)]
+	public static partial Regex GetMajorRegex();
+#else
+	private static readonly Regex majorRegex = new Regex(Major, Options);
+	public static Regex GetMajorRegex() => majorRegex;
+#endif
+
+#if NET7_0_OR_GREATER
+	[GeneratedRegex(MajorMinor, Options)]
+	public static partial Regex GetMajorMinorRegex();
+#else
+	private static readonly Regex majorMinorRegex = new Regex(MajorMinor, Options);
+	public static Regex GetMajorMinorRegex() => majorMinorRegex;
+#endif
+
+#if NET7_0_OR_GREATER
+	[GeneratedRegex(MajorMinorBuild, Options)]
+	public static partial Regex GetMajorMinorBuildRegex();
+#else
+	private static readonly Regex majorMinorBuildRegex = new Regex(MajorMinorBuild, Options);
+	public static Regex GetMajorMinorBuildRegex() => majorMinorBuildRegex;
+#endif
+
+#if NET7_0_OR_GREATER
+	[GeneratedRegex(Normal, Options)]
+	public static partial Regex GetNormalRegex();
+#else
+	private static readonly Regex normalRegex = new Regex(Normal, Options);
+	public static Regex GetNormalRegex() => normalRegex;
+#endif
+
+#if NET7_0_OR_GREATER
+	[GeneratedRegex(China, Options)]
+	public static partial Regex GetChinaRegex();
+#else
+	private static readonly Regex chinaRegex = new Regex(China, Options);
+	public static Regex GetChinaRegex() => chinaRegex;
+#endif
+}

AssetRipper.Primitives/Utf8String.cs

@@ -1,4 +1,4 @@
-#if NET7_0_OR_GREATER
+#if NET5_0_OR_GREATER || NETSTANDARD2_0_OR_GREATER || NET461_OR_GREATER
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using System.Text;
@@ -11,7 +11,12 @@ namespace AssetRipper.Primitives;
 /// <remarks>
 /// Conversions to and from <see cref="string"/> are handled by <see cref="Encoding.UTF8"/>.
 /// </remarks>
-public sealed class Utf8String : IEquatable<Utf8String>
+public sealed class Utf8String :
+#if NET7_0_OR_GREATER
+	System.Numerics.IEqualityOperators<Utf8String?, Utf8String?, bool>,
+    System.Numerics.IEqualityOperators<Utf8String?, string?, bool>,
+#endif
+    IEquatable<Utf8String>
 {
 	private readonly byte[] data;
 	private string? cachedString;
@@ -27,9 +32,13 @@ public sealed class Utf8String : IEquatable<Utf8String>
 		cachedString = "";
 	}
 
-	public Utf8String(ReadOnlySpan<byte> data)
+	public Utf8String(ReadOnlySpan<byte> data) : this(data.ToArray())
 	{
-		this.data = data.ToArray();
+	}
+
+	private Utf8String(byte[] data)
+	{
+		this.data = data;
 	}
 
 	public Utf8String(string @string)
@@ -56,7 +65,14 @@ public sealed class Utf8String : IEquatable<Utf8String>
 	public override int GetHashCode()
 	{
 		HashCode hash = new();
+#if NET6_0_OR_GREATER
 		hash.AddBytes(data);
+#else
+		foreach (byte b in data)
+		{
+			hash.Add(b);
+		}
+#endif
 		return hash.ToHashCode();
 	}
 
@@ -79,7 +95,11 @@ public sealed class Utf8String : IEquatable<Utf8String>
 	[return: NotNullIfNotNull(nameof(@string))]
 	public static implicit operator Utf8String?(string? @string)
 	{
-		return @string is null ? null : new Utf8String(@string);
+		return @string is null
+			? null
+			: @string.Length == 0
+				? Empty
+				: new Utf8String(@string);
 	}
 
 	[return: NotNullIfNotNull(nameof(utf8String))]
@@ -90,12 +110,207 @@ public sealed class Utf8String : IEquatable<Utf8String>
 
 	public static implicit operator Utf8String(ReadOnlySpan<byte> data)
 	{
-		return new Utf8String(data);
+		return data.Length == 0 ? Empty : new Utf8String(data);
 	}
 
 	public static implicit operator ReadOnlySpan<byte>(Utf8String? utf8String)
 	{
 		return utf8String is null ? default : utf8String.Data;
 	}
+
+	public static Utf8String operator +(Utf8String? string1, Utf8String? string2)
+	{
+		return Concat(string1, string2);
+	}
+
+	public static Utf8String operator +(Utf8String? string1, ReadOnlySpan<byte> string2)
+	{
+		return string1 is null
+			? string2.Length == 0 ? Empty : new Utf8String(string2)
+			: Concat(string1.Data, string2);
+	}
+
+	public static Utf8String operator +(ReadOnlySpan<byte> string1, Utf8String? string2)
+	{
+		return string2 is null
+			? string1.Length == 0 ? Empty : new Utf8String(string1)
+			: Concat(string1, string2.Data);
+	}
+
+	public static bool IsNullOrEmpty([NotNullWhen(false)] Utf8String? utf8String)
+	{
+		return utf8String is null || utf8String.IsEmpty;
+	}
+
+	public static Utf8String Concat(Utf8String? string1, Utf8String? string2)
+	{
+		if (IsNullOrEmpty(string1))
+		{
+			return string2 ?? Empty;
+		}
+		if (IsNullOrEmpty(string2))
+		{
+			return string1;
+		}
+
+		byte[] data = new byte[string1.data.Length + string2.data.Length];
+		string1.data.CopyTo(data.AsSpan());
+		string2.data.CopyTo(data.AsSpan(string1.data.Length));
+		return new Utf8String(data);
+	}
+
+	public static Utf8String Concat(Utf8String? string1, Utf8String? string2, Utf8String? string3)
+	{
+		if (IsNullOrEmpty(string1))
+		{
+			return Concat(string2, string3);
+		}
+		if (IsNullOrEmpty(string2))
+		{
+			return Concat(string1, string3);
+		}
+		if (IsNullOrEmpty(string3))
+		{
+			return Concat(string1, string2);
+		}
+
+		byte[] data = new byte[string1.data.Length + string2.data.Length + string3.data.Length];
+		string1.data.CopyTo(data.AsSpan());
+		string2.data.CopyTo(data.AsSpan(string1.data.Length));
+		string3.data.CopyTo(data.AsSpan(string1.data.Length + string2.data.Length));
+		return new Utf8String(data);
+	}
+
+	public static Utf8String Concat(Utf8String? string1, Utf8String? string2, Utf8String? string3, Utf8String? string4)
+	{
+		if (IsNullOrEmpty(string1))
+		{
+			return Concat(string2, string3, string4);
+		}
+		if (IsNullOrEmpty(string2))
+		{
+			return Concat(string1, string3, string4);
+		}
+		if (IsNullOrEmpty(string3))
+		{
+			return Concat(string1, string2, string4);
+		}
+		if (IsNullOrEmpty(string4))
+		{
+			return Concat(string1, string2, string3);
+		}
+
+		byte[] data = new byte[string1.data.Length + string2.data.Length + string3.data.Length + string4.data.Length];
+		string1.data.CopyTo(data.AsSpan());
+		string2.data.CopyTo(data.AsSpan(string1.data.Length));
+		string3.data.CopyTo(data.AsSpan(string1.data.Length + string2.data.Length));
+		string4.data.CopyTo(data.AsSpan(string1.data.Length + string2.data.Length + string3.data.Length));
+		return new Utf8String(data);
+	}
+
+	public static Utf8String Concat(params Utf8String?[] values)
+	{
+		if (values is null)
+		{
+			throw new ArgumentNullException(nameof(values));
+		}
+
+		int totalLength = 0;
+		foreach (Utf8String? value in values)
+		{
+			if (value is null)
+			{
+				continue;
+			}
+
+			totalLength += value.data.Length;
+		}
+
+		if (totalLength == 0)
+		{
+			return Empty;
+		}
+
+		byte[] data = new byte[totalLength];
+		int offset = 0;
+		foreach (Utf8String? value in values)
+		{
+			if (value is null)
+			{
+				continue;
+			}
+
+			value.data.CopyTo(data.AsSpan(offset));
+			offset += value.data.Length;
+		}
+
+		return new Utf8String(data);
+	}
+
+	public static Utf8String Concat(ReadOnlySpan<byte> string1, ReadOnlySpan<byte> string2)
+	{
+		if (string1.Length == 0)
+		{
+			return string2.Length == 0 ? Empty : new Utf8String(string2);
+		}
+		if (string2.Length == 0)
+		{
+			return new Utf8String(string1);
+		}
+
+		byte[] data = new byte[string1.Length + string2.Length];
+		string1.CopyTo(data);
+		string2.CopyTo(data.AsSpan(string1.Length));
+		return new Utf8String(data);
+	}
+
+	public static Utf8String Concat(ReadOnlySpan<byte> string1, ReadOnlySpan<byte> string2, ReadOnlySpan<byte> string3)
+	{
+		if (string1.Length == 0)
+		{
+			return Concat(string2, string3);
+		}
+		if (string2.Length == 0)
+		{
+			return Concat(string1, string3);
+		}
+		if (string3.Length == 0)
+		{
+			return Concat(string1, string2);
+		}
+
+		byte[] data = new byte[string1.Length + string2.Length + string3.Length];
+		string1.CopyTo(data);
+		string2.CopyTo(data.AsSpan(string1.Length));
+		string3.CopyTo(data.AsSpan(string1.Length + string2.Length));
+		return new Utf8String(data);
+	}
+
+	public static Utf8String Concat(ReadOnlySpan<byte> string1, ReadOnlySpan<byte> string2, ReadOnlySpan<byte> string3, ReadOnlySpan<byte> string4)
+	{
+		if (string1.Length == 0)
+		{
+			return Concat(string2, string3, string4);
+		}
+		if (string2.Length == 0)
+		{
+			return Concat(string1, string3, string4);
+		}
+		if (string3.Length == 0)
+		{
+			return Concat(string1, string2, string4);
+		}
+		if (string4.Length == 0)
+		{
+			return Concat(string1, string2, string3);
+		}
+
+		byte[] data = new byte[string1.Length + string2.Length + string3.Length + string4.Length];
+		string1.CopyTo(data);
+		string2.CopyTo(data.AsSpan(string1.Length));
+		string3.CopyTo(data.AsSpan(string1.Length + string2.Length));
+		string4.CopyTo(data.AsSpan(string1.Length + string2.Length + string3.Length));
+		return new Utf8String(data);
+	}
 }
 #endif