feat: add insertModeFactory

Author: helightdev

packages/dogs_core/lib/src/engine.dart

@@ -372,13 +372,37 @@ class DogEngine with MetadataMixin {
   }
 
   /// Registers a [OperationModeFactory] in this [DogEngine] instance and emits
-  /// a event to the change stream if [emitChangeToStream] is true.
+  /// a event to the change stream if [emitChangeToStream] is true. This
+  /// will override any previously registered factory for the given
+  /// [type] or the [factory]'s type argument.
   void registerModeFactory(OperationModeFactory factory,
       {bool emitChangeToStream = true, Type? type}) {
     _modeFactories[type ?? factory.typeArgument] = factory;
     if (emitChangeToStream) populateChange();
   }
 
+  /// Modifies the associated [OperationModeFactory] to insert the given
+  /// [factory] at the given [slot]. If no factory is registered for the given
+  /// [type] or the [factory]'s type argument, the [factory] will be registered
+  /// as new factory. If [emitChangeToStream] is true, a change event will be
+  /// emitted to the change stream.
+  void insertModeFactory(OperationModeFactory factory,
+      {bool emitChangeToStream = true,
+      Type? type,
+      ModeFactoryInsertionSlot slot = ModeFactoryInsertionSlot.first}) {
+    final arg = type ?? factory.typeArgument;
+    final currentFactory = _modeFactories[arg];
+    if (currentFactory == null) {
+      _modeFactories[arg] = factory;
+      if (emitChangeToStream) populateChange();
+      return;
+    }
+
+    final modified = currentFactory.insert(factory, slot);
+    _modeFactories[arg] = modified;
+    if (emitChangeToStream) populateChange();
+  }
+
   /// Registers multiple converters using [registerAutomatic].
   /// For more details see [DogEngine.registerAutomatic].
   void registerAllConverters(Iterable<DogConverter> converters) {

packages/dogs_core/lib/src/opmodes/factory.dart

@@ -39,8 +39,28 @@ abstract class OperationModeFactory<T extends OperationMode>
 
   /// A [OperationModeFactory] that composes multiple other factories.
   static OperationModeFactory<T> compose<T extends OperationMode>(
-          List<OperationModeFactory> factories) =>
-      ComposableOperationModeFactory<T>(factories);
+      List<OperationModeFactory> factories) {
+    final flattened = <OperationModeFactory>[];
+    for (var factory in factories) {
+      if (factory is ComposableOperationModeFactory<T>) {
+        flattened.addAll(factory._factories);
+      } else {
+        flattened.add(factory);
+      }
+    }
+    return ComposableOperationModeFactory<T>(flattened);
+  }
+
+  /// Composes this factory with another [insertion] factory, placing [insertion] in the specified [slot].
+  OperationModeFactory<T> insert(
+    OperationModeFactory<T> insertion,
+    ModeFactoryInsertionSlot slot,
+  ) =>
+      compose<T>([
+        if (slot == ModeFactoryInsertionSlot.first) insertion,
+        this,
+        if (slot == ModeFactoryInsertionSlot.last) insertion,
+      ]);
 }
 
 /// A [OperationModeFactory] that returns a single [OperationMode] for a [DogConverter] of [schema].
@@ -102,3 +122,12 @@ class ComposableOperationModeFactory<T extends OperationMode>
     return null;
   }
 }
+
+/// Specifies where to insert a [OperationModeFactory] when composing with another factory.
+enum ModeFactoryInsertionSlot {
+  /// Insert the factory at the beginning of the composition.
+  first,
+
+  /// Insert the factory at the end of the composition.
+  last
+}

packages/dogs_flutter/lib/dogs_flutter.dart

@@ -69,7 +69,7 @@ DogPlugin DogsFlutterPlugin({
     ...?binders,
     defaultFactories,
   ]);
-  engine.registerModeFactory(modeFactory, type: FlutterWidgetBinder);
+  engine.insertModeFactory(modeFactory, type: FlutterWidgetBinder, slot: ModeFactoryInsertionSlot.last);
 
   if (addSchemaContributors) {
     DogsMaterializer.get(