New cpp folder structure

Signed-off-by: Alexander Borsuk <me@alex.bio>

libs/indexer/feature_source.hpp

@@ -0,0 +1,62 @@
+#pragma once
+
+#include "indexer/feature.hpp"
+#include "indexer/features_vector.hpp"
+#include "indexer/mwm_set.hpp"
+
+#include "geometry/rect2d.hpp"
+
+#include <cstdint>
+#include <functional>
+#include <memory>
+#include <string>
+
+enum class FeatureStatus
+{
+  Untouched,  // The feature hasn't been saved in the editor.
+  Deleted,    // The feature has been marked as deleted.
+  Obsolete,   // The feature has been marked for deletion via note.
+  Modified,   // The feature has been saved in the editor and differs from the original one.
+  Created     // The feature was created by a user and has been saved in the editor.
+  // Note: If a feature was created by a user but hasn't been saved in the editor yet
+  // its status is Untouched.
+}; // enum class FeatureStatus
+
+std::string ToString(FeatureStatus fs);
+inline std::string DebugPrint(FeatureStatus fs) { return ToString(fs); }
+
+class FeatureSource
+{
+public:
+  explicit FeatureSource(MwmSet::MwmHandle const & handle);
+  virtual ~FeatureSource() = default;
+
+  size_t GetNumFeatures() const;
+
+  std::unique_ptr<FeatureType> GetOriginalFeature(uint32_t index) const;
+
+  MwmSet::MwmId const & GetMwmId() const { return m_handle.GetId(); }
+
+  virtual FeatureStatus GetFeatureStatus(uint32_t index) const;
+
+  virtual std::unique_ptr<FeatureType> GetModifiedFeature(uint32_t index) const;
+
+  // Runs |fn| for each feature, that is not present in the mwm.
+  virtual void ForEachAdditionalFeature(m2::RectD const & rect, int scale,
+                                        std::function<void(uint32_t)> const & fn) const;
+
+protected:
+  MwmSet::MwmHandle const & m_handle;
+  std::unique_ptr<FeaturesVector> m_vector;
+};
+
+// Lightweight FeatureSource factory. Each DataSource owns factory object.
+class FeatureSourceFactory
+{
+public:
+  virtual ~FeatureSourceFactory() = default;
+  virtual std::unique_ptr<FeatureSource> operator()(MwmSet::MwmHandle const & handle) const
+  {
+    return std::make_unique<FeatureSource>(handle);
+  }
+};