An engine object should be used for one column only, because the stored column name is part of the engine. If it would be used for more than one column, they would all share the same stored column. When the engine is bound to a column, it is checked if the name of that column matches the given virtual column name.
The engine can be used for a column containing any kind of array (thus direct or indirect, fixed or variable shaped)) as long as the virtual array can be stored in the stored array. Thus a fixed shaped virtual can use a variable shaped stored, but not vice versa. A fixed shape indirect virtual can use a stored with direct arrays.
Because the engine can serve only one column, it was possible to combine the engine and the column functionality in one class. This has been achieved using multiple inheritance. The advantage of this is that only one templated class is used, so less template instantiations are needed.
// Create the table description and 2 columns with indirect arrays in it.
// The Int column will be stored, while the double will be
// used as virtual.
TableDesc tableDesc ("", TableDesc::Scratch);
tableDesc.addColumn (ArrayColumnDesc<Int> ("storedArray"));
tableDesc.addColumn (ArrayColumnDesc<double> ("virtualArray"));
// Create a new table using the table description.
SetupNewTable newtab (tableDesc, "tab.data", Table::New);
// Create the array mapping engine to map from double to Int
// and bind it to the double column.
// Create the table.
MappedArrayEngine<double,Int> mappingEngine("virtualArray",
"storedArray", 10);
newtab.bindColumn ("virtualArray", mappingEngine);
Table table (newtab);
// Store a 3-D array (with dim. 2,3,4) into each row of the column.
// The shape of each array in the column is implicitly set by the put
// function. This will also set the shape of the underlying Int array.
ArrayColumn data (table, "virtualArray");
Array<double> someArray(IPosition(4,2,3,4));
someArray = 0;
for (uInt i=0, i<10; i++) { // table will have 10 rows
table.addRow();
data.put (i, someArray)
}
Construct from a record specification as created by dataManagerSpec().
Destructor is mandatory.
Return the type name of the engine (i.e. its class name).
Get the name given to the engine (is the virtual column name).
Record a record containing data manager specifications.
Return the name of the class. This includes the names of the template arguments.
Register the class name and the static makeObject "constructor".
This will make the engine known to the table system.
The automatically invoked registration function in DataManReg.cc
contains MappedArrayEngine
Assignment is not needed and therefore forbidden
(so it is made private and not implemented).
Clone the engine object.
Get an array in the given row.
Put an array in the given row.
Get a section of the array in the given row.
Put into a section of the array in the given row.
Get an entire column.
Put an entire column.
Get a section of all arrays in the column.
Put a section of all arrays in the column.
MappedArrayEngine (const MappedArrayEngine<VirtualType,StoredType>&)
Copy constructor is only used by clone().
(so it is made private).
MappedArrayEngine<VirtualType,StoredType>& operator= (const MappedArrayEngine<VirtualType,StoredType>&)
DataManager* clone() const
void getArray (uInt rownr, Array<VirtualType>& array)
void putArray (uInt rownr, const Array<VirtualType>& array)
void getSlice (uInt rownr, const Slicer& slicer, Array<VirtualType>& array)
void putSlice (uInt rownr, const Slicer& slicer, const Array<VirtualType>& array)
void getArrayColumn (Array<VirtualType>& array)
void putArrayColumn (const Array<VirtualType>& array)
void getColumnSlice (const Slicer& slicer, Array<VirtualType>& array)
void putColumnSlice (const Slicer& slicer, const Array<VirtualType>& array)
static DataManager* makeObject (const String& dataManagerType, const Record& spec)
Define the "constructor" to construct this engine when a
table is read back.
This "constructor" has to be registered by the user of the engine.
If the engine is commonly used, its registration can be added
to the registerAllCtor function in DataManReg.cc.
That function gets automatically invoked by the table system.