de.grogra.xl.lang
Class Aggregate

java.lang.Object
  de.grogra.xl.lang.Aggregate

public final class Aggregate
extends java.lang.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

java.lang.Object	aval This field contains the result if the type is a reference type.
java.lang.Object	aval1 This field may be used freely by aggregate methods.
java.lang.Object	aval2 This field may be used freely by aggregate methods.
java.lang.Object	aval3 This field may be used freely by aggregate methods.
java.lang.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

static Aggregate	allocate(java.lang.Class type)
static java.lang.Object	aval(Aggregate a)
static double	dval(Aggregate a)
static float	fval(Aggregate a)
java.lang.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 Detail

aval

public java.lang.Object aval

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

aval1

public java.lang.Object aval1

This field may be used freely by aggregate methods.

aval2

public java.lang.Object aval2

This field may be used freely by aggregate methods.

aval3

public java.lang.Object aval3

This field may be used freely by aggregate methods.

aval4

public java.lang.Object aval4

This field may be used freely by aggregate methods.

dval

public double dval

This field contains the result if the type is double.

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.

fval

public float fval

This field contains the result if the type is float.

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.

ival

public int ival

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

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.

lval

public long lval

This field contains the result if the type is long.

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.

Method Detail

allocate

public static Aggregate allocate(java.lang.Class type)

aval

public static java.lang.Object aval(Aggregate a)

dval

public static double dval(Aggregate a)

fval

public static float fval(Aggregate a)

getType

public java.lang.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

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

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

ival

public static int ival(Aggregate a)

lval

public static long lval(Aggregate a)

setFinished

public void setFinished()

Sets the finished-flags to true.

See Also:

isFinished()