Refactor ConventionScope

src/EFCore/Metadata/Builders/OwnedNavigationBuilder.cs

@@ -76,11 +76,11 @@ protected virtual InternalRelationshipBuilder Builder
         [EntityFrameworkInternal]
         protected virtual T UpdateBuilder<T>([NotNull] Func<T> configure)
         {
-            var foreignKey = _builder.Metadata;
+            IConventionForeignKey foreignKey = _builder.Metadata;
             var result = DependentEntityType.Model.ConventionDispatcher.Run(configure, ref foreignKey);
             if (foreignKey != null)
             {
-                _builder = foreignKey.Builder;
+                _builder = ((ForeignKey)foreignKey).Builder;
             }
 
             return result;

src/EFCore/Metadata/Conventions/Internal/ConventionDispatcher.ConventionNode.cs

@@ -0,0 +1,13 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal
+{
+    public partial class ConventionDispatcher
+    {
+        private abstract class ConventionNode
+        {
+            public abstract ConventionNode Accept(ConventionVisitor visitor);
+        }
+    }
+}

src/EFCore/Metadata/Conventions/Internal/ConventionDispatcher.ConventionScope.cs

@@ -0,0 +1,84 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using System.Reflection;
+using JetBrains.Annotations;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+
+namespace Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal
+{
+    public partial class ConventionDispatcher
+    {
+        private abstract class ConventionScope : ConventionNode
+        {
+            public virtual ConventionScope Parent => null;
+            public virtual IReadOnlyList<ConventionNode> Children => null;
+
+            public int GetLeafCount()
+            {
+                if (Children == null)
+                {
+                    return 0;
+                }
+
+                var scopesToVisit = new Queue<ConventionScope>();
+                scopesToVisit.Enqueue(this);
+                var leafCount = 0;
+                while (scopesToVisit.Count > 0)
+                {
+                    var scope = scopesToVisit.Dequeue();
+                    if (scope.Children == null)
+                    {
+                        continue;
+                    }
+
+                    foreach (var conventionNode in scope.Children)
+                    {
+                        if (conventionNode is ConventionScope nextScope)
+                        {
+                            scopesToVisit.Enqueue(nextScope);
+                        }
+                        else
+                        {
+                            leafCount++;
+                        }
+                    }
+                }
+
+                return leafCount;
+            }
+
+            public abstract IConventionEntityTypeBuilder OnEntityTypeAdded([NotNull] IConventionEntityTypeBuilder entityTypeBuilder);
+            public abstract IConventionAnnotation OnEntityTypeAnnotationChanged([NotNull] IConventionEntityTypeBuilder entityTypeBuilder, [NotNull] string name, [CanBeNull] IConventionAnnotation annotation, [CanBeNull] IConventionAnnotation oldAnnotation);
+            public abstract IConventionEntityType OnEntityTypeBaseTypeChanged([NotNull] IConventionEntityTypeBuilder entityTypeBuilder, [CanBeNull] IConventionEntityType newBaseType, [CanBeNull] IConventionEntityType previousBaseType);
+            public abstract string OnEntityTypeIgnored([NotNull] IConventionModelBuilder modelBuilder, [NotNull] string name, [CanBeNull] Type type);
+            public abstract string OnEntityTypeMemberIgnored([NotNull] IConventionEntityTypeBuilder entityTypeBuilder, [NotNull] string name);
+            public abstract IConventionKey OnEntityTypePrimaryKeyChanged([NotNull] IConventionEntityTypeBuilder entityTypeBuilder, [CanBeNull] IConventionKey newPrimaryKey, [CanBeNull] IConventionKey previousPrimaryKey);
+            public abstract IConventionEntityType OnEntityTypeRemoved([NotNull] IConventionModelBuilder modelBuilder, [NotNull] IConventionEntityType entityType);
+            public abstract IConventionRelationshipBuilder OnForeignKeyAdded([NotNull] IConventionRelationshipBuilder relationshipBuilder);
+            public abstract IConventionAnnotation OnForeignKeyAnnotationChanged(IConventionRelationshipBuilder relationshipBuilder, string name, IConventionAnnotation annotation, IConventionAnnotation oldAnnotation);
+            public abstract IConventionRelationshipBuilder OnForeignKeyOwnershipChanged([NotNull] IConventionRelationshipBuilder relationshipBuilder);
+            public abstract IConventionRelationshipBuilder OnForeignKeyPrincipalEndChanged([NotNull] IConventionRelationshipBuilder relationshipBuilder);
+            public abstract IConventionRelationshipBuilder OnForeignKeyPropertiesChanged([NotNull] IConventionRelationshipBuilder relationshipBuilder, [NotNull] IReadOnlyList<IConventionProperty> oldDependentProperties, [NotNull] IConventionKey oldPrincipalKey);
+            public abstract IConventionForeignKey OnForeignKeyRemoved([NotNull] IConventionEntityTypeBuilder entityTypeBuilder, [NotNull] IConventionForeignKey foreignKey);
+            public abstract IConventionRelationshipBuilder OnForeignKeyRequirednessChanged([NotNull] IConventionRelationshipBuilder relationshipBuilder);
+            public abstract IConventionRelationshipBuilder OnForeignKeyUniquenessChanged([NotNull] IConventionRelationshipBuilder relationshipBuilder);
+            public abstract IConventionIndexBuilder OnIndexAdded([NotNull] IConventionIndexBuilder indexBuilder);
+            public abstract IConventionAnnotation OnIndexAnnotationChanged([NotNull] IConventionIndexBuilder indexBuilder, [NotNull] string name, [CanBeNull] IConventionAnnotation annotation, [CanBeNull] IConventionAnnotation oldAnnotation);
+            public abstract IConventionIndex OnIndexRemoved([NotNull] IConventionEntityTypeBuilder entityTypeBuilder, [NotNull] IConventionIndex index);
+            public abstract IConventionIndexBuilder OnIndexUniquenessChanged([NotNull] IConventionIndexBuilder indexBuilder);
+            public abstract IConventionKeyBuilder OnKeyAdded([NotNull] IConventionKeyBuilder keyBuilder);
+            public abstract IConventionAnnotation OnKeyAnnotationChanged(IConventionKeyBuilder keyBuilder, string name, IConventionAnnotation annotation, IConventionAnnotation oldAnnotation);
+            public abstract IConventionKey OnKeyRemoved([NotNull] IConventionEntityTypeBuilder entityTypeBuilder, [NotNull] IConventionKey key);
+            public abstract IConventionAnnotation OnModelAnnotationChanged([NotNull] IConventionModelBuilder modelBuilder, [NotNull] string name, [CanBeNull] IConventionAnnotation annotation, [CanBeNull] IConventionAnnotation oldAnnotation);
+            public abstract IConventionNavigation OnNavigationAdded([NotNull] IConventionRelationshipBuilder relationshipBuilder, [NotNull] IConventionNavigation navigation);
+            public abstract string OnNavigationRemoved([NotNull] IConventionEntityTypeBuilder sourceEntityTypeBuilder, [NotNull] IConventionEntityTypeBuilder targetEntityTypeBuilder, [NotNull] string navigationName, [CanBeNull] MemberInfo memberInfo);
+            public abstract IConventionPropertyBuilder OnPropertyAdded([NotNull] IConventionPropertyBuilder propertyBuilder);
+            public abstract IConventionAnnotation OnPropertyAnnotationChanged([NotNull] IConventionPropertyBuilder propertyBuilder, [NotNull] string name, [CanBeNull] IConventionAnnotation annotation, [CanBeNull] IConventionAnnotation oldAnnotation);
+            public abstract FieldInfo OnPropertyFieldChanged([NotNull] IConventionPropertyBuilder propertyBuilder, FieldInfo newFieldInfo, [CanBeNull] FieldInfo oldFieldInfo);
+            public abstract IConventionPropertyBuilder OnPropertyNullableChanged([NotNull] IConventionPropertyBuilder propertyBuilder);
+        }
+    }
+}