Add flexible schema mapping POC

Realm/Realm.SourceGenerator/ClassBuilders/ClassCodeBuilderBase.cs

@@ -0,0 +1,118 @@
+////////////////////////////////////////////////////////////////////////////
+//
+// Copyright 2024 Realm Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License")
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+////////////////////////////////////////////////////////////////////////////
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Microsoft.CodeAnalysis.CSharp;
+
+namespace Realms.SourceGenerator;
+
+internal abstract class ClassCodeBuilderBase
+{
+    private readonly string[] _defaultNamespaces =
+    {
+        "MongoDB.Bson.Serialization",
+        "System",
+        "System.Collections.Generic",
+        "System.Linq",
+        "System.Runtime.CompilerServices",
+        "System.Runtime.Serialization",
+        "System.Xml.Serialization",
+        "System.Reflection",
+        "System.ComponentModel",
+        "Realms",
+        "Realms.Weaving",
+        "Realms.Schema",
+    };
+
+    protected readonly ClassInfo _classInfo;
+    protected readonly Lazy<string> _ignoreFieldAttribute;
+
+    protected string _baseInterface => $"I{_classInfo.ObjectType}";
+
+    protected ClassCodeBuilderBase(ClassInfo classInfo, GeneratorConfig generatorConfig)
+    {
+        _classInfo = classInfo;
+
+        _ignoreFieldAttribute = new(() =>
+        {
+            var result = "[IgnoreDataMember, XmlIgnore]";
+            var customAttribute = generatorConfig.CustomIgnoreAttribute;
+            if (!string.IsNullOrEmpty(customAttribute))
+            {
+                result += customAttribute;
+            }
+
+            return result;
+        });
+    }
+
+    public static ClassCodeBuilderBase CreateBuilder(ClassInfo classInfo, GeneratorConfig generatorConfig) => classInfo.ObjectType switch
+    {
+        ObjectType.MappedObject => new MappedObjectCodeBuilder(classInfo, generatorConfig),
+        ObjectType.AsymmetricObject or ObjectType.EmbeddedObject or ObjectType.RealmObject => new RealmObjectCodeBuilder(classInfo, generatorConfig),
+        _ => throw new NotSupportedException($"Unexpected ObjectType: {classInfo.ObjectType}")
+    };
+
+    public string GenerateSource()
+    {
+        var usings = GetUsings();
+
+        var classString = GeneratePartialClass();
+
+        foreach (var enclosingClass in _classInfo.EnclosingClasses)
+        {
+            classString = $@"{SyntaxFacts.GetText(enclosingClass.Accessibility)} partial class {enclosingClass.Name}
+{{
+{classString.Indent()}
+}}";
+        }
+
+        if (!_classInfo.NamespaceInfo.IsGlobal)
+        {
+            classString = $@"namespace {_classInfo.NamespaceInfo.OriginalName}
+{{
+{classString.Indent()}
+}}";
+        }
+
+        return $@"// <auto-generated />
+#nullable enable
+
+{usings}
+
+{classString}
+";
+    }
+
+    private string GetUsings()
+    {
+        var namespaces = new HashSet<string>(_defaultNamespaces);
+        namespaces.UnionWith(_classInfo.Usings);
+
+        if (!_classInfo.NamespaceInfo.IsGlobal)
+        {
+            namespaces.Add(_classInfo.NamespaceInfo.OriginalName);
+        }
+
+        return string.Join(Environment.NewLine, namespaces.Where(n => !string.IsNullOrWhiteSpace(n)).OrderBy(s => s).Select(s => $"using {s};"));
+    }
+
+    protected abstract string GeneratePartialClass();
+}

Realm/Realm.SourceGenerator/ClassBuilders/MappedObjectCodeBuilder.cs

@@ -0,0 +1,114 @@
+////////////////////////////////////////////////////////////////////////////
+//
+// Copyright 2024 Realm Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License")
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+////////////////////////////////////////////////////////////////////////////
+
+using Microsoft.CodeAnalysis.CSharp;
+
+namespace Realms.SourceGenerator;
+
+internal class MappedObjectCodeBuilder : ClassCodeBuilderBase
+{
+    public MappedObjectCodeBuilder(ClassInfo classInfo, GeneratorConfig generatorConfig) : base(classInfo, generatorConfig)
+    {
+    }
+
+    protected override string GeneratePartialClass()
+    {
+        var contents = @"private IDictionary<string, RealmValue> _backingStorage = null!;
+
+public void SetBackingStorage(IDictionary<string, RealmValue> dictionary)
+{
+    _backingStorage = dictionary;
+}";
+
+        return $@"[Generated]
+[Realms.Preserve(AllMembers = true)]
+{SyntaxFacts.GetText(_classInfo.Accessibility)} partial class {_classInfo.Name} : {_baseInterface}, INotifyPropertyChanged
+{{
+{contents.Indent()}
+
+{GetPropertyChanged().Indent()}
+}}";
+    }
+
+    private string GetPropertyChanged()
+    {
+        return _classInfo.HasPropertyChangedEvent ? string.Empty :
+            @"#region INotifyPropertyChanged
+
+private IDisposable? _notificationToken;
+
+private event PropertyChangedEventHandler? _propertyChanged;
+
+/// <inheritdoc />
+public event PropertyChangedEventHandler? PropertyChanged
+{
+    add
+    {
+        if (_propertyChanged == null)
+        {
+            SubscribeForNotifications();
+        }
+
+        _propertyChanged += value;
+    }
+
+    remove
+    {
+        _propertyChanged -= value;
+
+        if (_propertyChanged == null)
+        {
+            UnsubscribeFromNotifications();
+        }
+    }
+}
+
+partial void OnPropertyChanged(string? propertyName);
+
+private void RaisePropertyChanged([CallerMemberName] string propertyName = """")
+{
+    _propertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+    OnPropertyChanged(propertyName);
+}
+
+private void SubscribeForNotifications()
+{
+    _notificationToken = _backingStorage.SubscribeForKeyNotifications((sender, changes) =>
+    {
+        if (changes == null)
+        {
+            return;
+        }
+
+        foreach (var key in changes.ModifiedKeys)
+        {
+            RaisePropertyChanged(key);
+        }
+
+        // TODO: what do we do with deleted/inserted keys
+    });
+}
+
+private void UnsubscribeFromNotifications()
+{
+    _notificationToken?.Dispose();
+}
+
+#endregion";
+    }
+}