expose GetObjectsReferencing in ChangeContext

src/SIL.Harmony.Tests/ConfigTests.cs

@@ -0,0 +1,32 @@
+using SIL.Harmony.Sample.Changes;
+using SIL.Harmony.Sample.Models;
+using SIL.Harmony.Tests.Adapter;
+
+namespace SIL.Harmony.Tests;
+
+public class ConfigTests
+{
+    [Fact]
+    public void CanGetEntityTypes()
+    {
+        var config = new CrdtConfig();
+        config.ObjectTypeListBuilder.DefaultAdapter()
+            .Add<Word>()
+            .Add<Definition>();
+        config.ObjectTypeListBuilder
+            .CustomAdapter<CustomObjectAdapterTests.IMyCustomInterface, CustomObjectAdapterTests.MyClassAdapter>()
+            .Add<CustomObjectAdapterTests.MyClass>();
+        var types = config.ObjectTypes.ToArray();
+        types.Should().BeEquivalentTo([typeof(Word), typeof(Definition), typeof(CustomObjectAdapterTests.MyClass)]);
+    }
+
+    [Fact]
+    public void CanGetChangeTypes()
+    {
+        var config = new CrdtConfig();
+        config.ChangeTypeListBuilder.Add<NewDefinitionChange>();
+        config.ChangeTypeListBuilder.Add<SetWordTextChange>();
+        var types = config.ChangeTypes.ToArray();
+        types.Should().BeEquivalentTo([typeof(NewDefinitionChange), typeof(SetWordTextChange)]);
+    }
+}

src/SIL.Harmony/Changes/ChangeContext.cs

@@ -17,6 +17,10 @@ internal ChangeContext(Commit commit, SnapshotWorker worker, CrdtConfig crdtConf
 
     public Commit Commit { get; }
     public async ValueTask<ObjectSnapshot?> GetSnapshot(Guid entityId) => await _worker.GetSnapshot(entityId);
+    public IAsyncEnumerable<object> GetObjectsReferencing(Guid entityId, bool includeDeleted = false)
+    {
+        return _worker.GetSnapshotsReferencing(entityId, includeDeleted).Select(s => s.Entity.DbObject);
+    }
     public async ValueTask<T?> GetCurrent<T>(Guid entityId) where T : class
     {
         var snapshot = await GetSnapshot(entityId);

src/SIL.Harmony/CrdtConfig.cs

@@ -23,7 +23,9 @@ public class CrdtConfig
     /// </summary>
     public bool AlwaysValidateCommits { get; set; } = true;
     public ChangeTypeListBuilder ChangeTypeListBuilder { get; } = new();
+    public IEnumerable<Type> ChangeTypes => ChangeTypeListBuilder.Types.Select(t => t.DerivedType);
     public ObjectTypeListBuilder ObjectTypeListBuilder { get; } = new();
+    public IEnumerable<Type> ObjectTypes => ObjectTypeListBuilder.AdapterProviders.SelectMany(p => p.GetRegistrations().Select(r => r.ObjectDbType));
     public JsonSerializerOptions JsonSerializerOptions => _lazyJsonSerializerOptions.Value;
     private readonly Lazy<JsonSerializerOptions> _lazyJsonSerializerOptions;
 

src/SIL.Harmony/SnapshotWorker.cs

@@ -125,7 +125,7 @@ private async ValueTask ApplyCommitChanges(IEnumerable<Commit> commits, bool upd
                 {
                     intermediateSnapshots[prevSnapshot.Entity.Id] = prevSnapshot;
                 }
-                
+
                 await _crdtConfig.BeforeSaveObject.Invoke(entity.DbObject, newSnapshot);
 
                 AddSnapshot(newSnapshot);
@@ -202,6 +202,13 @@ private async ValueTask MarkDeleted(Guid deletedEntityId, Commit commit)
         return snapshot;
     }
 
+    internal IAsyncEnumerable<ObjectSnapshot> GetSnapshotsReferencing(Guid entityId, bool includeDeleted = false)
+    {
+        return _crdtRepository.CurrentSnapshots()
+            .Where(s => (includeDeleted || !s.EntityIsDeleted) && s.References.Contains(entityId))
+            .AsAsyncEnumerable();
+    }
+
     private void AddSnapshot(ObjectSnapshot snapshot)
     {
         if (snapshot.IsRoot)