Refactor factories to use injectable delegates

Author: commonsensesoftware

src/AspNetCore/WebApi/src/Asp.Versioning.Http/Builder/ApiVersionSetBuilderFactory.cs

@@ -0,0 +1,10 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+
+namespace Asp.Versioning.Builder;
+
+/// <summary>
+/// Creates and returns a new API version set builder.
+/// </summary>
+/// <param name="name">The name of the API associated with the builder, if any.</param>
+/// <returns>A new <see cref="ApiVersionSetBuilder">API version set builder</see>.</returns>
+public delegate ApiVersionSetBuilder ApiVersionSetBuilderFactory( string? name = default );

src/AspNetCore/WebApi/src/Asp.Versioning.Http/Builder/DefaultApiVersionSetBuilderFactory.cs

@@ -27,9 +27,9 @@ public static class IEndpointRouteBuilderExtensions
             throw new ArgumentNullException( nameof( endpoints ) );
         }
 
-        var factory = endpoints.ServiceProvider.GetRequiredService<IApiVersionSetBuilderFactory>();
+        var create = endpoints.ServiceProvider.GetService<ApiVersionSetBuilderFactory>();
 
-        return factory.Create( name );
+        return create is null ? new ApiVersionSetBuilder( name ) : create( name );
     }
 
     /// <summary>
@@ -52,11 +52,9 @@ public static class IEndpointRouteBuilderExtensions
             throw new InvalidOperationException( SR.CannotNestVersionSet );
         }
 
-        var factory = builder.ServiceProvider.GetRequiredService<IApiVersionSetBuilderFactory>();
-
         builder.Finally( EndpointBuilderFinalizer.FinalizeRoutes );
 
-        return new VersionedEndpointRouteBuilder( builder, builder, factory.Create( name ) );
+        return builder.NewVersionedEndpointRouteBuilder( builder, builder, name );
     }
 
     /// <summary>
@@ -79,11 +77,25 @@ public static class IEndpointRouteBuilderExtensions
 
         var group = builder.MapGroup( string.Empty );
         IEndpointConventionBuilder convention = group;
-        var factory = builder.ServiceProvider.GetRequiredService<IApiVersionSetBuilderFactory>();
 
         convention.Finally( EndpointBuilderFinalizer.FinalizeRoutes );
 
-        return new VersionedEndpointRouteBuilder( group, group, factory.Create( name ) );
+        return builder.NewVersionedEndpointRouteBuilder( group, group, name );
+    }
+
+    [MethodImpl( MethodImplOptions.AggressiveInlining )]
+    private static IVersionedEndpointRouteBuilder NewVersionedEndpointRouteBuilder(
+        this IEndpointRouteBuilder builder,
+        IEndpointRouteBuilder routeBuilder,
+        IEndpointConventionBuilder conventionBuilder,
+        string? name )
+    {
+        var create = builder.ServiceProvider.GetService<VersionedEndpointRouteBuilderFactory>();
+        var versionSet = builder.NewApiVersionSet( name );
+
+        return create is null ?
+               new VersionedEndpointRouteBuilder( routeBuilder, conventionBuilder, versionSet ) :
+               create( routeBuilder, conventionBuilder, versionSet );
     }
 
     [MethodImpl( MethodImplOptions.AggressiveInlining )]

src/AspNetCore/WebApi/src/Asp.Versioning.Http/Builder/IApiVersionSetBuilderFactory.cs

@@ -0,0 +1,19 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+
+namespace Asp.Versioning.Builder;
+
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Routing;
+
+/// <summary>
+/// Creates and returns a new versioned endpoint route builder.
+/// </summary>
+/// <param name="routeBuilder">The inner <see cref="IEndpointRouteBuilder"/> the new instance decorates.</param>
+/// <param name="conventionBuilder">The inner <see cref="IEndpointConventionBuilder"/> the new instance decorates.</param>
+/// <param name="apiVersionSetBuilder">The associated <see cref="ApiVersionSetBuilder">API version set builder</see>.</param>
+/// <returns>A new <see cref="IVersionedEndpointRouteBuilder"/> instance.</returns>
+[CLSCompliant( false )]
+public delegate IVersionedEndpointRouteBuilder VersionedEndpointRouteBuilderFactory(
+    IEndpointRouteBuilder routeBuilder,
+    IEndpointConventionBuilder conventionBuilder,
+    ApiVersionSetBuilder apiVersionSetBuilder );

src/AspNetCore/WebApi/src/Asp.Versioning.Http/Builder/IEndpointRouteBuilderExtensions.cs

@@ -84,7 +84,6 @@ private static void AddApiVersioningServices( IServiceCollection services )
             throw new ArgumentNullException( nameof( services ) );
         }
 
-        services.TryAddSingleton<IApiVersionSetBuilderFactory, DefaultApiVersionSetBuilderFactory>();
         services.TryAddSingleton<IApiVersionParser, ApiVersionParser>();
         services.Add( Singleton( sp => sp.GetRequiredService<IOptions<ApiVersioningOptions>>().Value.ApiVersionReader ) );
         services.Add( Singleton( sp => (IApiVersionParameterSource) sp.GetRequiredService<IOptions<ApiVersioningOptions>>().Value.ApiVersionReader ) );