[indexer] Implemented CentersTable.

1 files changed, 79 insertions, 0 deletions

diff --git a/indexer/centers_table.hpp b/indexer/centers_table.hpp
new file mode 100644
index 0000000000..7c67eed682
--- /dev/null
+++ b/indexer/centers_table.hpp
@@ -0,0 +1,79 @@
+#pragma once
+
+#include "geometry/point2d.hpp"
+
+#include "std/cstdint.hpp"
+#include "std/unique_ptr.hpp"
+#include "std/vector.hpp"
+
+class Reader;
+class Writer;
+
+namespace serial
+{
+class CodingParams;
+}
+
+namespace search
+{
+// A wrapper class around serialized centers-table.
+//
+// *NOTE* This wrapper is abstract enough so feel free to change it,
+// but note that there should always be backward-compatibility.  Thus,
+// when adding new versions, never change data format of old versions.
+//
+// All centers tables are serialized in the following format:
+//
+// File offset (bytes)  Field name  Field size (bytes)
+// 0                    version     2
+// 2                    endiannes   2
+//
+// Version and endiannes is always in stored little-endian format.  0
+// value of endiannes means little endian, whereas 1 means big endian.
+class CentersTable
+{
+public:
+  struct Header
+  {
+    void Read(Reader & reader);
+    void Write(Writer & writer);
+    bool IsValid() const;
+
+    uint16_t m_version = 0;
+    uint16_t m_endiannes = 0;
+  };
+
+  static_assert(sizeof(Header) == 4, "Wrong header size");
+
+  virtual ~CentersTable() = default;
+
+  // Tries to get |center| of the feature identified by |id|.  Returns
+  // false if table does not have entry for the feature.
+  virtual bool Get(uint32_t id, m2::PointD & center) = 0;
+
+  // Loads CentersTable instance. Note that |reader| must be alive
+  // until the destruction of loaded table. Returns nullptr if
+  // CentersTable can't be loaded.
+  static unique_ptr<CentersTable> Load(Reader & reader, serial::CodingParams const & codingParams);
+
+private:
+  virtual bool Init() = 0;
+};
+
+class CentersTableBuilder
+{
+public:
+  CentersTableBuilder(Writer & writer, serial::CodingParams const & codingParams);
+
+  ~CentersTableBuilder();
+
+  void Put(uint32_t featureId, m2::PointD const & center);
+
+private:
+  Writer & m_writer;
+  serial::CodingParams const & m_codingParams;
+
+  vector<m2::PointU> m_centers;
+  vector<uint32_t> m_ids;
+};
+}  // namespace search