Module xl.core

Package de.grogra.xl.lang

Class Aggregate

java.lang.Object

de.grogra.xl.lang.Aggregate

public final class Aggregate
extends Object

An instance of Aggregate is used in aggregate method invocations as specified by the XL programming language. Aggregate methods use such an instance to collect the information about a sequence of values which they need to compute an aggregate value.

Author:

Ole Kniemeyer

Field Summary

Fields

Modifier and Type	Field	Description
Object	aval	This field contains the result if the type is a reference type.
Object	aval1	This field may be used freely by aggregate methods.
Object	aval2	This field may be used freely by aggregate methods.
Object	aval3	This field may be used freely by aggregate methods.
Object	aval4	This field may be used freely by aggregate methods.
double	dval	This field contains the result if the type is double.
double	dval1	This field may be used freely by aggregate methods.
double	dval2	This field may be used freely by aggregate methods.
double	dval3	This field may be used freely by aggregate methods.
double	dval4	This field may be used freely by aggregate methods.
float	fval	This field contains the result if the type is float.
float	fval1	This field may be used freely by aggregate methods.
float	fval2	This field may be used freely by aggregate methods.
float	fval3	This field may be used freely by aggregate methods.
float	fval4	This field may be used freely by aggregate methods.
int	ival	This field contains the result if the type is boolean, byte, short, char, or int.
int	ival1	This field may be used freely by aggregate methods.
int	ival2	This field may be used freely by aggregate methods.
int	ival3	This field may be used freely by aggregate methods.
int	ival4	This field may be used freely by aggregate methods.
long	lval	This field contains the result if the type is long.
long	lval1	This field may be used freely by aggregate methods.
long	lval2	This field may be used freely by aggregate methods.
long	lval3	This field may be used freely by aggregate methods.
long	lval4	This field may be used freely by aggregate methods.

Method Summary

Modifier and Type	Method	Description
static Aggregate	allocate(Class type)
static Object	aval(Aggregate a)
static double	dval(Aggregate a)
static float	fval(Aggregate a)
Class	getType()	Returns the result type of the aggregation.
boolean	initialize()	Returns true the first time it is invoked.
boolean	isFinished()	Returns true iff setFinished() has been called previously.
static int	ival(Aggregate a)
static long	lval(Aggregate a)
void	setFinished()	Sets the finished-flags to true.

Methods inherited from class java.lang.Object

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

Field Details

ival

public int ival

This field contains the result if the type is boolean, byte, short, char, or int.

lval

public long lval

This field contains the result if the type is long.

fval

public float fval

This field contains the result if the type is float.

dval

public double dval

This field contains the result if the type is double.

aval

public Object aval

This field contains the result if the type is a reference type. It has to be of the type returned by getType().

ival1

public int ival1

This field may be used freely by aggregate methods.

ival2

public int ival2

This field may be used freely by aggregate methods.

ival3

public int ival3

This field may be used freely by aggregate methods.

ival4

public int ival4

This field may be used freely by aggregate methods.

lval1

public long lval1

This field may be used freely by aggregate methods.

lval2

public long lval2

This field may be used freely by aggregate methods.

lval3

public long lval3

This field may be used freely by aggregate methods.

lval4

public long lval4

This field may be used freely by aggregate methods.

fval1

public float fval1

This field may be used freely by aggregate methods.

fval2

public float fval2

This field may be used freely by aggregate methods.

fval3

public float fval3

This field may be used freely by aggregate methods.

fval4

public float fval4

This field may be used freely by aggregate methods.

dval1

public double dval1

This field may be used freely by aggregate methods.

dval2

public double dval2

This field may be used freely by aggregate methods.

dval3

public double dval3

This field may be used freely by aggregate methods.

dval4

public double dval4

This field may be used freely by aggregate methods.

aval1

public Object aval1

This field may be used freely by aggregate methods.

aval2

public Object aval2

This field may be used freely by aggregate methods.

aval3

public Object aval3

This field may be used freely by aggregate methods.

aval4

public Object aval4

This field may be used freely by aggregate methods.

Method Details

allocate

public static Aggregate allocate(Class type)

ival

public static int ival(Aggregate a)

lval

public static long lval(Aggregate a)

fval

public static float fval(Aggregate a)

dval

public static double dval(Aggregate a)

aval

public static Object aval(Aggregate a)

initialize

public boolean initialize()

Returns true the first time it is invoked. This has to be queried in implementations of aggregate methods to initialize their computation.

Returns:

true iff this method is invoked the first time for a specific invocation of an aggregate method

setFinished

public void setFinished()

Sets the finished-flags to true.

See Also:

• isFinished()

isFinished

public boolean isFinished()

Returns true iff setFinished() has been called previously. This is used for two purposes:

1. To indicate the aggregate method implementation that no more values are available for aggregation. The aggregate method has to compute the final result and place it in the appropriate field (ival, lval, fval, dval, or aval).
2. To indicate the invoker of the aggregate method that the computation of the aggregate value has been completed by the aggregate method, even if there are values left for aggregation. E.g., this is the case for a shortcut-implementation of the boolean or where the result is known when the first true-value is encountered. The invoker must not invoke the aggregate method again.

Returns:

true iff setFinished() has been called previously

getType

public Class getType()

Returns the result type of the aggregation. This has to be respected by aggregate method implementations which compute aggregate values of reference type.

Returns:

the result type

See Also:

• aval