skeleton of decision tree regressor added

lib/src/di/dependencies.dart

@@ -26,6 +26,8 @@ import 'package:ml_algo/src/math/randomizer/randomizer_factory.dart';
 import 'package:ml_algo/src/math/randomizer/randomizer_factory_impl.dart';
 import 'package:ml_algo/src/model_selection/data_splitter/data_splitter_factory.dart';
 import 'package:ml_algo/src/model_selection/data_splitter/data_splitter_factory_impl.dart';
+import 'package:ml_algo/src/regressor/decision_tree_regressor/decision_tree_regressor_factory.dart';
+import 'package:ml_algo/src/regressor/decision_tree_regressor/decision_tree_regressor_factory_impl.dart';
 import 'package:ml_algo/src/regressor/knn_regressor/knn_regressor_factory.dart';
 import 'package:ml_algo/src/regressor/knn_regressor/knn_regressor_factory_impl.dart';
 
@@ -74,4 +76,7 @@ Injector get dependencies =>
               (injector) => KnnRegressorFactoryImpl(
                 injector.getDependency<KernelFactory>(),
                 injector.getDependency<KnnSolverFactory>(),
-          ));
+          ))
+
+      ..registerSingleton<DecisionTreeRegressorFactory>(
+              (_) => const DecisionTreeRegressorFactoryImpl());

lib/src/regressor/decision_tree_regressor/_helpers/create_decision_tree_regressor.dart

@@ -0,0 +1,10 @@
+import 'package:ml_algo/src/di/dependencies.dart';
+import 'package:ml_algo/src/regressor/decision_tree_regressor/decision_tree_regressor.dart';
+import 'package:ml_algo/src/regressor/decision_tree_regressor/decision_tree_regressor_factory.dart';
+
+DecisionTreeRegressor createDecisionTreeRegressor() {
+  final regressorFactory = dependencies
+      .getDependency<DecisionTreeRegressorFactory>();
+
+  return regressorFactory.create();
+}

lib/src/regressor/decision_tree_regressor/decision_tree_regressor.dart

@@ -0,0 +1,5 @@
+import 'package:ml_algo/src/regressor/decision_tree_regressor/_helpers/create_decision_tree_regressor.dart';
+
+abstract class DecisionTreeRegressor {
+  factory DecisionTreeRegressor() => createDecisionTreeRegressor();
+}

lib/src/regressor/decision_tree_regressor/decision_tree_regressor_factory.dart

@@ -0,0 +1,5 @@
+import 'package:ml_algo/src/regressor/decision_tree_regressor/decision_tree_regressor.dart';
+
+abstract class DecisionTreeRegressorFactory {
+  DecisionTreeRegressor create();
+}

lib/src/regressor/decision_tree_regressor/decision_tree_regressor_factory_impl.dart

@@ -0,0 +1,10 @@
+import 'package:ml_algo/src/regressor/decision_tree_regressor/decision_tree_regressor.dart';
+import 'package:ml_algo/src/regressor/decision_tree_regressor/decision_tree_regressor_factory.dart';
+import 'package:ml_algo/src/regressor/decision_tree_regressor/decision_tree_regressor_impl.dart';
+
+class DecisionTreeRegressorFactoryImpl implements DecisionTreeRegressorFactory {
+  const DecisionTreeRegressorFactoryImpl();
+
+  @override
+  DecisionTreeRegressor create() => DecisionTreeRegressorImpl();
+}

lib/src/regressor/decision_tree_regressor/decision_tree_regressor_impl.dart

@@ -0,0 +1,5 @@
+import 'package:ml_algo/src/regressor/decision_tree_regressor/decision_tree_regressor.dart';
+
+class DecisionTreeRegressorImpl implements DecisionTreeRegressor {
+
+}