uk.ac.starlink.ttools.plot2.task

Class JELDataSpec

java.lang.Object

uk.ac.starlink.ttools.plot2.data.AbstractDataSpec

uk.ac.starlink.ttools.plot2.task.JELDataSpec

All Implemented Interfaces:

DataSpec

public class JELDataSpec
extends AbstractDataSpec

DataSpec implementation that works with JEL expressions. The mask and coord ID values are based on strings which are evaluated as JEL expressions in the context of the DataSpec's table. The constraints on ID equality are therefore met since equal expression strings applied against the same table must yield the same values.

Since:

1 Mar 2013

Author:

Mark Taylor

Constructor Summary

Constructors

Constructor and Description
JELDataSpec(StarTable table, String maskExpr, CoordValue[] coordValues) Constructor.

Method Summary

Modifier and Type	Method and Description
UserDataReader	createUserDataReader() Returns an object that can be used to read the mask and coordinate values from a row sequence derived from this object's source table.
Coord	getCoord(int ic) Returns the coord reader that can read the data for one of this object's output columns.
int	getCoordCount() Returns the number of columns that this object produces.
String[]	getCoordExpressions(int ic) Returns the user input strings used to supply the value for a given coordinate in this DataSpec.
String	getCoordId(int ic) Returns an identifier for one of the the columns produced by this object.
String	getMaskId() Returns an identifier for the row mask for this object.
StarTable	getSourceTable() Returns the table object from which this data spec's data is obtained.
ValueInfo[]	getUserCoordInfos(int ic) Returns the metadata, if known, for the values supplied by the user to provide data for one of this object's output columns.
DomainMapper[]	getUserCoordMappers(int ic) Returns the domain mappers to use for the values supplied by the user to provide data for one of this object's output columns.
boolean	isCoordBlank(int icoord) Indicates whether the value for a given coord specified by this object is known to have a constant, blank value in all cases.
boolean	isMaskTrue() Indicates whether the mask flag specified by this object is known always to be true.

Methods inherited from class uk.ac.starlink.ttools.plot2.data.AbstractDataSpec

equals, hashCode

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

JELDataSpec

public JELDataSpec(StarTable table,
                   String maskExpr,
                   CoordValue[] coordValues)
            throws TaskException

Constructor.

Parameters:

table - table containing data

maskExpr - JEL boolean expression giving mask inclusion; null may be used to indicate unconditional inclusion

coordValues - coordinate definitions for which columns are required, along with the JEL expressions for their values; note that the DomainMapper array is permitted to have missing elements

Throws:

TaskException

Method Detail

getSourceTable

public StarTable getSourceTable()

Description copied from interface: DataSpec

Returns the table object from which this data spec's data is obtained.

Returns:

data source table

getCoordCount

public int getCoordCount()

Description copied from interface: DataSpec

Returns the number of columns that this object produces.

Returns:

TupleSequence column count

getCoordId

public String getCoordId(int ic)

Description copied from interface: DataSpec

Returns an identifier for one of the the columns produced by this object. Coords with the same identifier must mean the same thing, and preferably vice versa.

Parameters:

ic - column index

Returns:

column identifier

getCoord

public Coord getCoord(int ic)

Description copied from interface: DataSpec

Returns the coord reader that can read the data for one of this object's output columns.

Parameters:

ic - column index

Returns:

column data reader

getMaskId

public String getMaskId()

Description copied from interface: DataSpec

Returns an identifier for the row mask for this object. Masks with the same identifier must mean the same thing, and preferably vice versa.

Returns:

mask identifier

getUserCoordInfos

public ValueInfo[] getUserCoordInfos(int ic)

Description copied from interface: DataSpec

Returns the metadata, if known, for the values supplied by the user to provide data for one of this object's output columns.

Parameters:

ic - column index

Returns:

array of value infos for column data inputs; elements may be null if not known

getUserCoordMappers

public DomainMapper[] getUserCoordMappers(int ic)

Description copied from interface: DataSpec

Returns the domain mappers to use for the values supplied by the user to provide data for one of this object's output columns. These objects define how the input values as supplied by the user are to be interpreted as the expected input values for this dataspec. In many cases this mapping is trivial (for instance Y axis coordinate), but in some (for instance absolute epoch) it may not be.

Parameters:

ic - column index

Returns:

array of DomainMappers for column data inputs

createUserDataReader

public UserDataReader createUserDataReader()

Description copied from interface: DataSpec

Returns an object that can be used to read the mask and coordinate values from a row sequence derived from this object's source table. A given UserDataReader can only be used from a single thread, but multiple returns from this method may be used concurrently in different threads.

Returns:

new data reader

isMaskTrue

public boolean isMaskTrue()

Description copied from interface: DataSpec

Indicates whether the mask flag specified by this object is known always to be true. If true is returned, then getUserDataReader().getMaskFlag will always return true. False negatives are permitted; even if the result is false, the mask may in fact always return true.

Returns:

true if all rows are known to be included in the mask

isCoordBlank

public boolean isCoordBlank(int icoord)

Description copied from interface: DataSpec

Indicates whether the value for a given coord specified by this object is known to have a constant, blank value in all cases. Clients don't have to test this, since data stores will always dispense the relevant blank value based on this data spec, and should do so in an efficient manner, but it may be useful for clients to know in advance that a column is blank all the way down. False negatives are permitted: even if the result is false, the column may in fact have all blank values.

Parameters:

icoord - column index

Returns:

true if all values in the column are always blank

getCoordExpressions

public String[] getCoordExpressions(int ic)

Returns the user input strings used to supply the value for a given coordinate in this DataSpec.

Parameters:

ic - coordinate index

Returns:

array of JEL expressions entered by the user to provide data for the coordinate