New cpp folder structure

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

libs/routing/checkpoint_predictor.hpp

@@ -0,0 +1,44 @@
+#pragma once
+
+#include "geometry/point2d.hpp"
+
+#include <cstdint>
+#include <iterator>
+#include <vector>
+
+namespace routing
+{
+/// \brief This class is responsable for prediction of the order of intermediate route points.
+/// According to current implementation to find the best place for an adding intermediate points
+/// this class inserts an added intermediate point between points at vector
+/// {<route start>, <former intermediate points>, <route finish>}, calculates the length
+/// of the broken line in meters, and finds the sequence of points which gets the shortest length.
+class CheckpointPredictor final
+{
+  friend class CheckpointPredictorTest;
+
+public:
+  CheckpointPredictor(m2::PointD const & start, m2::PointD const & finish)
+    : m_start(start), m_finish(finish)
+  {
+  }
+
+  /// \returns difference between distance |from|->|between| + |between|->|to| and distance |from|->|to|.
+  static double CalculateDeltaMeters(m2::PointD const & from, m2::PointD const & to, m2::PointD const & between);
+
+  /// \brief finds the best position for |point| between |points| to minimize the length
+  /// of broken line of |m_start|, |points| and |m_finish| with inserted |point| between them.
+  /// \param points is a sequence of points on the map.
+  /// \param point is a point to be inserted between |points|.
+  /// \returns zero based index of a line segment between two points at |points|.
+  size_t PredictPosition(std::vector<m2::PointD> const & points, m2::PointD const & point) const;
+
+private:
+  /// \returns checkpoint by its |index|.
+  /// \note checkpoints is a sequence of points: |m_start|, |points|, |m_finish|.
+  m2::PointD const & GetCheckpoint(std::vector<m2::PointD> const & points, size_t index) const;
+
+  m2::PointD const m_start;
+  m2::PointD const m_finish;
+};
+}  // namespace routing