add UUIDv7 generation option

README.md

@@ -243,8 +243,8 @@ namespace UnitGenerator
         {
             this.Type = typeof(T);
             this.Options = options;
-        }
-    }
+        }
+    }
 #endif
 }
 ```
@@ -283,11 +283,15 @@ public static bool operator false(Foo x) => !x.value;
 public static bool operator !(Foo x) => !x.value;
 ```
 
-> When type is Guid or [Ulid](https://github.com/Cysharp/Ulid), also implements `New()` and `New***()` static operator.
+> When type is Guid or [Ulid](https://github.com/Cysharp/Ulid), also implements `New()` and `New***()` static operator.<br />
+> For Guid type in .NET 9.0 or later, these methods accept an optional `uuidV7` parameter. When `uuidV7` is set to `true`, the methods use `Guid.CreateVersion7()` internally.
 
 ```csharp
 public static GroupId New();
 public static GroupId NewGroupId();
+// overload .NET 9.0+
+public static GroupId New(bool uuidV7);
+public static GroupId NewGroupId(bool uuidV7);
 ```
 
 Second parameter `UnitGenerateOptions options` can configure which method to implement, default is `None`.

UnitGenerator.sln

@@ -19,6 +19,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "FileGenerate", "sandbox\Fil
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "EntityFrameworkApp", "src\EntityFrameworkApp\EntityFrameworkApp.csproj", "{51AE7857-4223-40FE-AEA9-F0E64C5F8238}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "UnitGenerator.NET9.Tests", "tests\UnitGenerator.NET9.Tests\UnitGenerator.NET9.Tests.csproj", "{EAC3A025-E49B-4719-8738-9C3B67484A4A}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -45,6 +47,10 @@ Global
 		{51AE7857-4223-40FE-AEA9-F0E64C5F8238}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{51AE7857-4223-40FE-AEA9-F0E64C5F8238}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{51AE7857-4223-40FE-AEA9-F0E64C5F8238}.Release|Any CPU.Build.0 = Release|Any CPU
+		{EAC3A025-E49B-4719-8738-9C3B67484A4A}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{EAC3A025-E49B-4719-8738-9C3B67484A4A}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{EAC3A025-E49B-4719-8738-9C3B67484A4A}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{EAC3A025-E49B-4719-8738-9C3B67484A4A}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -55,6 +61,7 @@ Global
 		{5DA06D43-A023-4464-B856-8BB42E8E4A05} = {187FBF64-D2AA-444D-AFB1-CE999BC6AD34}
 		{F8353A7A-290E-41D7-A6F8-8D8DBDD44433} = {34EB4113-923D-4855-979C-A0467461B75C}
 		{51AE7857-4223-40FE-AEA9-F0E64C5F8238} = {34EB4113-923D-4855-979C-A0467461B75C}
+		{EAC3A025-E49B-4719-8738-9C3B67484A4A} = {187FBF64-D2AA-444D-AFB1-CE999BC6AD34}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {A64DF779-7829-414F-9E6E-3AF349486508}

src/UnitGenerator/SourceGenerator.cs

@@ -554,6 +554,18 @@ public bool TryFormat (Span<byte> utf8Destination, out int bytesWritten, ReadOnl
             return new {{unitTypeName}}(Guid.NewGuid());
         }
 
+#if NET9_0_OR_GREATER        
+        public static {{unitTypeName}} New(bool uuidV7)
+        {
+            return new {{unitTypeName}}(uuidV7 ? Guid.CreateVersion7() : Guid.NewGuid());
+        }
+
+        public static {{unitTypeName}} New{{unitTypeName}}(bool uuidV7)
+        {
+            return new {{unitTypeName}}(uuidV7 ? Guid.CreateVersion7() : Guid.NewGuid());
+        }
+#endif
+
 """);
             }
 

tests/UnitGenerator.NET9.Tests/UnitGenerator.NET9.Tests.csproj

@@ -0,0 +1,25 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net9.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <IsPackable>false</IsPackable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="coverlet.collector" Version="6.0.2" />
+    <PackageReference Include="FluentAssertions" Version="6.12.2" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.11.1" />
+    <PackageReference Include="xunit" Version="2.9.2" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\src\UnitGenerator\UnitGenerator.csproj" OutputItemType="Analyzer" ReferenceOutputAssembly="false" />
+  </ItemGroup>
+
+	<ItemGroup>
+    <Using Include="Xunit" />
+  </ItemGroup>
+
+</Project>

tests/UnitGenerator.NET9.Tests/UnitOfGuidTests.cs

@@ -0,0 +1,35 @@
+using FluentAssertions;
+using System;
+
+namespace UnitGenerator.NET9.Tests;
+
+public class UnitOfGuidTests
+{
+    [Fact]
+    public void Guidv7_v4_Comparison_AsExpected()
+    {
+        // v7
+        TryGetUuidV7Timestamp(Guidv7Unit.New(uuidV7: true).AsPrimitive(), out var v).Should().BeTrue();
+        // ...approximate check
+        v?.ToString("yyyyMMdd").Should().Be(DateTime.UtcNow.ToString("yyyyMMdd"));
+        TryGetUuidV7Timestamp(Guidv7Unit.New().AsPrimitive(), out var _).Should().BeFalse();
+    }
+
+    static bool TryGetUuidV7Timestamp(Guid uuid, out DateTimeOffset? timestamp)
+    {
+        timestamp = null;
+        var uuidString = uuid.ToString("N");
+        // version number is the 13th character
+        if (uuidString[12] == '7')
+        {
+            var timestampHex = uuidString.Substring(0, 12);
+            var milliseconds = Convert.ToInt64(timestampHex, 16);
+            timestamp = DateTimeOffset.FromUnixTimeMilliseconds(milliseconds);
+            return true;
+        }
+        else return false;
+    }
+}
+
+[UnitOf<Guid>()]
+public readonly partial struct Guidv7Unit { }