New cpp folder structure

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

libs/descriptions/loader.cpp

@@ -0,0 +1,36 @@
+#include "descriptions/loader.hpp"
+
+#include "indexer/data_source.hpp"
+
+#include "base/assert.hpp"
+
+#include "defines.hpp"
+
+namespace descriptions
+{
+std::string Loader::GetWikiDescription(FeatureID const & featureId, std::vector<int8_t> const & langPriority)
+{
+  auto const handle = m_dataSource.GetMwmHandleById(featureId.m_mwmId);
+
+  if (!handle.IsAlive())
+    return {};
+
+  auto const & value = *handle.GetValue();
+
+  if (!value.m_cont.IsExist(DESCRIPTIONS_FILE_TAG))
+    return {};
+
+  EntryPtr entry;
+  {
+    std::lock_guard<std::mutex> lock(m_mutex);
+    entry = m_deserializers.try_emplace(featureId.m_mwmId, std::make_shared<Entry>()).first->second;
+  }
+
+  ASSERT(entry, ());
+
+  auto readerPtr = value.m_cont.GetReader(DESCRIPTIONS_FILE_TAG);
+
+  std::lock_guard<std::mutex> lock(entry->m_mutex);
+  return entry->m_deserializer.Deserialize(*readerPtr.GetPtr(), featureId.m_index, langPriority);
+}
+}  // namespace descriptions