Minor fixes for MatchProcessorFactory

Fixing minor issues found doing DFA integration.

src/Microsoft.AspNetCore.Routing/Matchers/DefaultMatchProcessorFactory.cs

@@ -3,7 +3,6 @@
 
 using System;
 using Microsoft.Extensions.DependencyInjection;
-using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 
 namespace Microsoft.AspNetCore.Routing.Matchers
@@ -11,16 +10,13 @@ namespace Microsoft.AspNetCore.Routing.Matchers
     internal class DefaultMatchProcessorFactory : MatchProcessorFactory
     {
         private readonly RouteOptions _options;
-        private readonly ILogger<DefaultMatchProcessorFactory> _logger;
         private readonly IServiceProvider _serviceProvider;
 
         public DefaultMatchProcessorFactory(
             IOptions<RouteOptions> options,
-            ILogger<DefaultMatchProcessorFactory> logger,
             IServiceProvider serviceProvider)
         {
             _options = options.Value;
-            _logger = logger;
             _serviceProvider = serviceProvider;
         }
 
@@ -67,13 +63,16 @@ namespace Microsoft.AspNetCore.Routing.Matchers
             {
                 throw new InvalidOperationException(
                     Resources.FormatDefaultInlineConstraintResolver_TypeNotConstraint(
-                        constraintType, constraintName, typeof(IRouteConstraint).Name));
+                        constraintType,
+                        constraintName,
+                        typeof(IRouteConstraint).Name));
             }
 
             try
             {
                 return CreateMatchProcessorFromRouteConstraint(
                     matchProcessorReference.ParameterName,
+                    matchProcessorReference.Optional,
                     constraintType,
                     constraintArgument);
             }
@@ -91,11 +90,20 @@ namespace Microsoft.AspNetCore.Routing.Matchers
 
         private MatchProcessor CreateMatchProcessorFromRouteConstraint(
             string parameterName,
+            bool optional,
             Type constraintType,
             string constraintArgument)
         {
             var routeConstraint = DefaultInlineConstraintResolver.CreateConstraint(constraintType, constraintArgument);
-            return (new MatchProcessorReference(parameterName, routeConstraint)).MatchProcessor;
+            var matchProcessor = new MatchProcessorReference(parameterName, routeConstraint).MatchProcessor;
+            if (optional)
+            {
+                matchProcessor = new OptionalMatchProcessor(matchProcessor);
+            }
+
+            matchProcessor.Initialize(parameterName, constraintArgument);
+
+            return matchProcessor;
         }
 
         private MatchProcessor ResolveMatchProcessor(

test/Microsoft.AspNetCore.Routing.Tests/DefaultLinkGeneratorTest.cs

@@ -801,7 +801,6 @@ namespace Microsoft.AspNetCore.Routing
             return new DefaultLinkGenerator(
                 new DefaultMatchProcessorFactory(
                     Options.Create(new RouteOptions()),
-                    NullLogger<DefaultMatchProcessorFactory>.Instance,
                     Mock.Of<IServiceProvider>()),
                 new DefaultObjectPool<UriBuildingContext>(new UriBuilderContextPooledObjectPolicy()),
                 NullLogger<DefaultLinkGenerator>.Instance);

test/Microsoft.AspNetCore.Routing.Tests/Matchers/DefaultMatchProcessorFactoryTest.cs

@@ -56,6 +56,20 @@ namespace Microsoft.AspNetCore.Routing.Matchers
             Assert.False(isMatch);
         }
 
+        [Fact]
+        public void Create_CreatesMatchProcessor_FromConstraintText_AndRouteConstraint_Optional()
+        {
+            // Arrange
+            var factory = GetMatchProcessorFactory();
+            var matchProcessorReference = new MatchProcessorReference("id", true, "int");
+
+            // Act
+            var processor = factory.Create(matchProcessorReference);
+
+            // Assert
+            Assert.IsType<OptionalMatchProcessor>(processor);
+        }
+
         [Fact]
         public void Create_CreatesMatchProcessor_FromConstraintText_AndCustomMatchProcessor()
         {
@@ -143,7 +157,6 @@ namespace Microsoft.AspNetCore.Routing.Matchers
 
             return new DefaultMatchProcessorFactory(
                 Options.Create(options),
-                NullLogger<DefaultMatchProcessorFactory>.Instance,
                 services.BuildServiceProvider());
         }
 

test/Microsoft.AspNetCore.Routing.Tests/Matchers/TreeMatcherTests.cs

@@ -33,7 +33,6 @@ namespace Microsoft.AspNetCore.Routing.Matchers
             var compositeDataSource = new CompositeEndpointDataSource(new[] { endpointDataSource });
             var defaultInlineConstraintResolver = new DefaultMatchProcessorFactory(
                 Options.Create(new RouteOptions()),
-                NullLogger<DefaultMatchProcessorFactory>.Instance,
                 Mock.Of<IServiceProvider>());
             var endpointSelector = new EndpointSelector(
                 compositeDataSource,