some thoughts about cursors, nothing special yet

src/cursor.h

@@ -19,6 +19,9 @@
 #ifndef LMDBAL_CURSOR_H
 #define LMDBAL_CURSOR_H
 
+#include <string>
+
+#include "lmdb.h"
 #include "base.h"
 #include "storage.h"
 
@@ -28,18 +31,45 @@ template <class K, class V>
 class Cursor {
     friend class Storage<K, V>;
 private:
+    enum State {            /**<Cursor state:*/
+        closed,             /**<    - closed*/
+        openedPublic,       /**<    - opened with public transaction, all storages will be notified about it after it's done*/
+        openedPrivate       /**<    - opened with private transaction, only current storage will be notified when cursor is closed*/
+    };
+
     Cursor(Storage<K, V>* parent);
     ~Cursor();
 
 public:
-    void open();
-    void close();
+    void open() const;
+    void open(TransactionID txn) const;
+    void renew() const;
+    void renew(TransactionID txn) const;
+    void close() const;
+
+    std::pair<K, V> first() const;
+    std::pair<K, V> last() const;
+    std::pair<K, V> next() const;
+    std::pair<K, V> prev() const;
+    std::pair<K, V> current() const;
+
+    void first(std::pair<K, V>& out) const;
+    void last(std::pair<K, V>& out) const;
+    void next(std::pair<K, V>& out) const;
+    void prev(std::pair<K, V>& out) const;
+    void current(std::pair<K, V>& out) const;
 
 private:
-    void terminated();
+    void terminated() const;
 
 private:
     Storage<K, V>* storage;
+    mutable MDB_cursor* cursor;
+    mutable State state;
+
+    inline static const std::string openRecordMethodName = "Cursor::open";   /**<\brief member function name, just for exceptions*/
+    inline static const std::string closeRecordMethodName = "Cursor::close"; /**<\brief member function name, just for exceptions*/
+    inline static const std::string renewRecordMethodName = "Cursor::renew"; /**<\brief member function name, just for exceptions*/
 };
 
 };