uk.ac.starlink.ttools.plottask

Class TablePointSequence

java.lang.Object

uk.ac.starlink.ttools.plottask.TablePointSequence

All Implemented Interfaces:

PointSequence

public abstract class TablePointSequence
extends Object
implements PointSequence

PointSequence abstract superclass implementation for getting sequential plot data from a table.

Since:

13 Aug 2008

Author:

Mark Taylor

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	TablePointSequence(SequentialJELRowReader rseq, String labelExpr, String[] setExprs) Constructor.

Method Summary

Modifier and Type	Method and Description
void	close() Call when this sequence is no longer required.
protected Object	evaluate(gnu.jel.CompiledExpression compex) Convenience method which evaluates an Object-valued compiled expression.
protected double	evaluateDouble(gnu.jel.CompiledExpression compex) Convenience method which evaluates a numeric-valued compiled expression.
String	getLabel() Returns any text label associated with the current point.
boolean	isIncluded(int iset) Indicates whether the current row is included in the given subset.
boolean	next() Attempts to advance the current row to the next one.

Methods inherited from class java.lang.Object

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

Methods inherited from interface uk.ac.starlink.ttools.plot.PointSequence

getErrors, getPoint

Constructor Detail

TablePointSequence

protected TablePointSequence(SequentialJELRowReader rseq,
                             String labelExpr,
                             String[] setExprs)
                      throws gnu.jel.CompilationException

Constructor.

Parameters:

rseq - row sequence representing the table which contains the actual data

labelExpr - JEL expression for text labellling each point; may be null for no label; may have any type (converted to string before use)

setExprs - nset-element array of boolean-valued JEL expressions giving per-set point inclusion status

Throws:

gnu.jel.CompilationException

Method Detail

next

public boolean next()

Description copied from interface: PointSequence

Attempts to advance the current row to the next one. If true is returned the attempt has been successful, and if false is returned there are no more rows in this sequence. Since the initial position of this sequence is before the first row, this method must be called before calling any of the data access methods.

Specified by:

next in interface PointSequence

Returns:

true if row advance has succeeded, false for end of sequence

getLabel

public String getLabel()

Description copied from interface: PointSequence

Returns any text label associated with the current point.

Specified by:

getLabel in interface PointSequence

Returns:

text label, or null

isIncluded

public boolean isIncluded(int iset)

Description copied from interface: PointSequence

Indicates whether the current row is included in the given subset.

Specified by:

isIncluded in interface PointSequence

Returns:

true iff set iset is included

close

public void close()

Description copied from interface: PointSequence

Call when this sequence is no longer required.

Specified by:

close in interface PointSequence

evaluate

protected Object evaluate(gnu.jel.CompiledExpression compex)

Convenience method which evaluates an Object-valued compiled expression. Any resulting exceptions are rethrown as PlotDataExceptions.

Parameters:

compex - compiled expression

Returns:

expression value

evaluateDouble

protected double evaluateDouble(gnu.jel.CompiledExpression compex)

Convenience method which evaluates a numeric-valued compiled expression. Any resulting exceptions are rethrown as PlotDataExceptions.

Parameters:

compex - compiled expression

Returns:

expression value