casacore::BitFlagsEngine< StoredType > Class Template Reference

Templated virtual column engine to map bit flags to a Bool. More...

#include <BitFlagsEngine.h>

Inheritance diagram for casacore::BitFlagsEngine< StoredType >:

Classes
struct	BoolToFlags
	Functor to convert Bools to flags using a mask. More...
struct	FlagsToBool
	Functor to and an array and mask and convert to Bool. More...
Public Member Functions
	BitFlagsEngine (const String &virtualColumnName, const String &storedColumnName, StoredType readMask=StoredType(0xffffffff), StoredType writeMask=1)
	Construct an engine to map integer arrays in a column to Bool arrays.
	BitFlagsEngine (const String &virtualColumnName, const String &storedColumnName, const Array< String > &readMaskKeys, const Array< String > &writeMaskKeys)
	Construct an engine to map integer arrays in a column to Bool arrays.
	BitFlagsEngine (const Record &spec)
	Construct from a record specification as created by dataManagerSpec().
	~BitFlagsEngine ()
	Destructor is mandatory.
virtual String	dataManagerType () const
	Return the type name of the engine (i.e.
virtual String	dataManagerName () const
	Get the name given to the engine (is the virtual column name).
virtual Record	dataManagerSpec () const
	Record a record containing data manager specifications.
virtual Record	getProperties () const
	Get data manager properties that can be modified.
virtual void	setProperties (const Record &spec)
	Modify data manager properties.
Static Public Member Functions
static String	className ()
	Return the name of the class.
static void	registerClass ()
	Register the class name and the static makeObject "constructor".
static DataManager *	makeObject (const String &dataManagerType, const Record &spec)
	Define the "constructor" to construct this engine when a table is read back.
Private Member Functions
	BitFlagsEngine (const BitFlagsEngine< StoredType > &)
	Copy constructor is only used by clone().
BitFlagsEngine< StoredType > &	operator= (const BitFlagsEngine< StoredType > &)
	Assignment is not needed and therefore forbidden (so it is made private and not implemented).
DataManager *	clone () const
	Clone the engine object.
void	create (uInt initialNrrow)
	Initialize the object for a new table.
void	prepare ()
	Preparing consists of setting the writable switch and adding the initial number of rows in case of create.
void	getArray (uInt rownr, Array< Bool > &array)
	Get an array in the given row.
void	putArray (uInt rownr, const Array< Bool > &array)
	Put an array in the given row.
void	getSlice (uInt rownr, const Slicer &slicer, Array< Bool > &array)
	Get a section of the array in the given row.
void	putSlice (uInt rownr, const Slicer &slicer, const Array< Bool > &array)
	Put into a section of the array in the given row.
void	getArrayColumn (Array< Bool > &array)
	Get an entire column.
void	putArrayColumn (const Array< Bool > &array)
	Put an entire column.
virtual void	getArrayColumnCells (const RefRows &rownrs, Array< Bool > &data)
	Get some array values in the column.
virtual void	putArrayColumnCells (const RefRows &rownrs, const Array< Bool > &data)
	Put some array values in the column.
void	getColumnSlice (const Slicer &slicer, Array< Bool > &array)
	Get a section of all arrays in the column.
void	putColumnSlice (const Slicer &slicer, const Array< Bool > &array)
	Put a section of all arrays in the column.
virtual void	getColumnSliceCells (const RefRows &rownrs, const Slicer &slicer, Array< Bool > &data)
	Get a section of some arrays in the column.
virtual void	putColumnSliceCells (const RefRows &rownrs, const Slicer &slicer, const Array< Bool > &data)
	Put into a section of some arrays in the column.
void	mapOnGet (Array< Bool > &array, const Array< StoredType > &stored)
	Map bit flags array to Bool array.
void	mapOnPut (const Array< Bool > &array, Array< StoredType > &stored)
	Map Bool array to bit flags array.
Private Attributes
BFEngineMask	itsBFEReadMask
BFEngineMask	itsBFEWriteMask
StoredType	itsReadMask
StoredType	itsWriteMask
Bool	itsIsNew

Detailed Description

template<typename StoredType>
class casacore::BitFlagsEngine< StoredType >

Templated virtual column engine to map bit flags to a Bool.

Intended use:

Public interface

Review Status

Reviewed By:: Gareth Hunt
Date Reviewed:: 94Nov17

Prerequisite

Synopsis

BitFlagsEngine is a virtual column engine which maps an integer column containing flag bits to a Bool column. It can be used in a MeasurementSet to have multiple flag categories, yet use all existing software that deals with the Bool FLAG column.

The engine support read as well as write access. For both cases a mask can be defined telling which bits have to be taken into account. For example, when writing to the Bool FLAG column, the data in the bitflags column twill be or-ed with the bits as defined in the writemask. Similary when reading FLAG, only the bits of the readmask are taken into account.

The masks can be defined in two ways:

The mask can be given directly as an integer value. The default write mask is 1 (thus only bit 0), while the default read mask is all bits.
Symbolic names for mask bits can be defined as keywords in the flagbits column. They define the bit value, not the bit number. It makes it possible to combine bits in a keyword. The keywords are stored in a subrecord of keyword FLAGSETS. Example of keyword and their values could be:
RFI=1, CAL=2, CLIP=4, OTHER=8, RFICAL=3
Note that in this example RFICAL is defined such that it contains RFI and CAL.

A mask can be set at construction time, but it can be changed at runtime using the setProperties function. The masks are kept in special keywords (which are different from the keywords defining the flag bits), so it is possible to change a mask by changing those keywords before opening a table. However, that is not recommended.

BitFlagsEngine is known to the table system for data types uChar, Short, and Int.

Motivation

The FLAG_CATEGORY defined the Measurement does not work because adding an extra flag means resizing the entire array which is slow. This class makes it possible to use an integer column to store flags and map it directly to a Bool column.

Example

 // Create the table description and 2 columns with indirect arrays in it.
 // The Int column will be stored, while the Bool will be used as virtual.
 TableDesc tableDesc ("", TableDesc::Scratch);
 tableDesc.addColumn (ArrayColumnDesc<Int> ("BitBlags"));
 tableDesc.addColumn (ArrayColumnDesc<Bool> ("FLAG"));
 
 // Create a new table using the table description.
 SetupNewTable newtab (tableDesc, "tab.data", Table::New);
 
 // Create the engine and bind the FLAG column to it.
 BitFlagsEngine<Int> flagsEngine("FLAG", "BitFlags");
 newtab.bindColumn ("FLAG", flagsEngine);
 // Create the table.
 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<Bool> someArray(IPosition(4,2,3,4));
 someArray = True;
 for (uInt i=0, i<10; i++) {          // table will have 10 rows
 table.addRow();
 data.put (i, someArray)
 }

The underlying integer array will be stored according to the writemask which defaults to 1.

Template Type Argument Requirements (StoredType)

only suited for built-in integer data types

Definition at line 170 of file BitFlagsEngine.h.

Constructor & Destructor Documentation

template<typename StoredType>

casacore::BitFlagsEngine< StoredType >::BitFlagsEngine	(	const String &	virtualColumnName,
		const String &	storedColumnName,
		StoredType	readMask = `StoredType(0xffffffff)`,
		StoredType	writeMask = `1`
	)

Construct an engine to map integer arrays in a column to Bool arrays.

StoredColumnName is the name of the column where the integer data will be put and must have data type StoredType. The virtual column using this engine must have data type Bool.
A mask can be given that specifies which bits to use in the mapping from StoredType to Bool. Similarly a mask can be given defining which bits to set when mapping from Bool to StoredType.

template<typename StoredType>

casacore::BitFlagsEngine< StoredType >::BitFlagsEngine	(	const String &	virtualColumnName,
		const String &	storedColumnName,
		const Array< String > &	readMaskKeys,
		const Array< String > &	writeMaskKeys
	)

Construct an engine to map integer arrays in a column to Bool arrays.

StoredColumnName is the name of the column where the scaled data will be put and must have data type StoredType. The virtual column using this engine must have data type Bool.
A mask can be given that specifies which bits to use in the mapping from StoredType to Bool. Similarly a mask can be given defining which bits to set when mapping from Bool to StoredType. The masks are given using the values of keywords in the stored column. Each keyword should be an integer defining one or more bits and can be seen as a symbolic name. The keyword values are or-ed to form the mask. The keywords are stored in a subrecord of keyword FLAGSETS.

template<typename StoredType>

casacore::BitFlagsEngine< StoredType >::BitFlagsEngine ( const Record & spec )

Construct from a record specification as created by dataManagerSpec().

template<typename StoredType>

casacore::BitFlagsEngine< StoredType >::~BitFlagsEngine ( )

Destructor is mandatory.

template<typename StoredType>

casacore::BitFlagsEngine< StoredType >::BitFlagsEngine ( const BitFlagsEngine< StoredType > & ) [private]

Copy constructor is only used by clone().

(so it is made private).

Member Function Documentation

template<typename StoredType>

static String casacore::BitFlagsEngine< StoredType >::className ( ) [static]

Return the name of the class.

This includes the names of the template arguments.

template<typename StoredType>

DataManager* casacore::BitFlagsEngine< StoredType >::clone ( ) const [private, virtual]

Clone the engine object.

Implements casacore::DataManager.

template<typename StoredType>

void casacore::BitFlagsEngine< StoredType >::create ( uInt initialNrrow ) [private, virtual]

Initialize the object for a new table.

It defines the keywords containing the engine parameters.

Reimplemented from casacore::BaseMappedArrayEngine< Bool, StoredType >.

template<typename StoredType>

virtual String casacore::BitFlagsEngine< StoredType >::dataManagerName ( ) const [virtual]

Get the name given to the engine (is the virtual column name).

Reimplemented from casacore::DataManager.

template<typename StoredType>

virtual Record casacore::BitFlagsEngine< StoredType >::dataManagerSpec ( ) const [virtual]

Record a record containing data manager specifications.

Reimplemented from casacore::DataManager.

template<typename StoredType>

virtual String casacore::BitFlagsEngine< StoredType >::dataManagerType ( ) const [virtual]

Return the type name of the engine (i.e.

its class name).

Implements casacore::DataManager.

template<typename StoredType>

void casacore::BitFlagsEngine< StoredType >::getArray	(	uInt	rownr,
		Array< Bool > &	array
	)			`[private, virtual]`

Get an array in the given row.

This will scale and offset from the underlying array.

Reimplemented from casacore::BaseMappedArrayEngine< Bool, StoredType >.

template<typename StoredType>

void casacore::BitFlagsEngine< StoredType >::getArrayColumn ( Array< Bool > & array ) [private, virtual]

Get an entire column.

This will scale and offset from the underlying array.

Reimplemented from casacore::BaseMappedArrayEngine< Bool, StoredType >.

template<typename StoredType>

virtual void casacore::BitFlagsEngine< StoredType >::getArrayColumnCells	(	const RefRows &	rownrs,
		Array< Bool > &	data
	)			`[private, virtual]`

Get some array values in the column.

This will scale and offset from the underlying array.

Reimplemented from casacore::BaseMappedArrayEngine< Bool, StoredType >.

template<typename StoredType>

void casacore::BitFlagsEngine< StoredType >::getColumnSlice	(	const Slicer &	slicer,
		Array< Bool > &	array
	)			`[private, virtual]`

Get a section of all arrays in the column.

This will scale and offset from the underlying array.

Reimplemented from casacore::BaseMappedArrayEngine< Bool, StoredType >.

template<typename StoredType>

virtual void casacore::BitFlagsEngine< StoredType >::getColumnSliceCells	(	const RefRows &	rownrs,
		const Slicer &	slicer,
		Array< Bool > &	data
	)			`[private, virtual]`

Get a section of some arrays in the column.

This will scale and offset from the underlying array.

Reimplemented from casacore::BaseMappedArrayEngine< Bool, StoredType >.

template<typename StoredType>

virtual Record casacore::BitFlagsEngine< StoredType >::getProperties ( ) const [virtual]

Get data manager properties that can be modified.

These are ReadMask, WriteMask, ReadMaskKeys, and WriteMaskKeys. It is a subset of the data manager specification.

Reimplemented from casacore::DataManager.

template<typename StoredType>

void casacore::BitFlagsEngine< StoredType >::getSlice	(	uInt	rownr,
		const Slicer &	slicer,
		Array< Bool > &	array
	)			`[private, virtual]`

Get a section of the array in the given row.

This will scale and offset from the underlying array.

Reimplemented from casacore::BaseMappedArrayEngine< Bool, StoredType >.

template<typename StoredType>

static DataManager* casacore::BitFlagsEngine< StoredType >::makeObject	(	const String &	dataManagerType,
		const Record &	spec
	)			`[static]`

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.

template<typename StoredType>

void casacore::BitFlagsEngine< StoredType >::mapOnGet	(	Array< Bool > &	array,
		const Array< StoredType > &	stored
	)			`[private, virtual]`

Map bit flags array to Bool array.

This is meant when reading an array from the stored column.

Reimplemented from casacore::BaseMappedArrayEngine< Bool, StoredType >.

template<typename StoredType>

void casacore::BitFlagsEngine< StoredType >::mapOnPut	(	const Array< Bool > &	array,
		Array< StoredType > &	stored
	)			`[private, virtual]`

Map Bool array to bit flags array.

This is meant when writing an array into the stored column.

Reimplemented from casacore::BaseMappedArrayEngine< Bool, StoredType >.

template<typename StoredType>

BitFlagsEngine<StoredType>& casacore::BitFlagsEngine< StoredType >::operator= ( const BitFlagsEngine< StoredType > & ) [private]

Assignment is not needed and therefore forbidden (so it is made private and not implemented).

Reimplemented from casacore::VirtualColumnEngine.

template<typename StoredType>

void casacore::BitFlagsEngine< StoredType >::prepare ( ) [private, virtual]

Preparing consists of setting the writable switch and adding the initial number of rows in case of create.

Furthermore it reads the keywords containing the engine parameters.

Reimplemented from casacore::BaseMappedArrayEngine< Bool, StoredType >.

template<typename StoredType>

void casacore::BitFlagsEngine< StoredType >::putArray	(	uInt	rownr,
		const Array< Bool > &	array
	)			`[private, virtual]`

Put an array in the given row.