Add getFirstSnapshot()

source/RobotAPI/libraries/armem/core/base/EntityBase.h

@@ -178,12 +178,25 @@ namespace armarx::armem::base
         {
             return const_cast<EntitySnapshotT&>(const_cast<const EntityBase*>(this)->getLatestSnapshot());
         }
-
         const EntitySnapshotT& getLatestSnapshot() const
         {
             return getLatestItem().second;
         }
 
+        /**
+         * @brief Return the snapshot with the most recent timestamp.
+         * @return The latest snapshot.
+         * @throw `armem::error::EntityHistoryEmpty` If the history is empty.
+         */
+        EntitySnapshotT& getFirstSnapshot()
+        {
+            return const_cast<EntitySnapshotT&>(const_cast<const EntityBase*>(this)->getFirstSnapshot());
+        }
+        const EntitySnapshotT& getFirstSnapshot() const
+        {
+            return getFirstItem().second;
+        }
+
 
         /**
          * @brief Return the lastest snapshot before time.
@@ -541,6 +554,23 @@ namespace armarx::armem::base
             return *this->_container.rbegin();
         }
 
+        /**
+         * @brief Return the snapshot with the least recent timestamp.
+         * @return The first snapshot.
+         * @throw `armem::error::EntityHistoryEmpty` If the history is empty.
+         */
+        virtual
+        const typename ContainerT::value_type&
+        getFirstItem() const
+        {
+            if (this->_container.empty())
+            {
+                throw armem::error::EntityHistoryEmpty(name(), "when getting the first snapshot.");
+            }
+            return *this->_container.begin();
+        }
+
+
     };
 
 }