org.abora.white.cross
Class TupleStepper

java.lang.Object
  |
  +--org.abora.white.xpp.basic.Heaper
        |
        +--org.abora.white.collection.steppers.Stepper
              |
              +--org.abora.white.cross.TupleStepper

public class TupleStepper

extends Stepper

A stepper for stepping through the positions in a simple cross region in order according to a lexicographic composition of OrderSpecs of each of the projections of the region. See CrossOrderSpec.NOT.A.TYPE

Field Summary

protected PrimIntArray	myLexOrder
protected CrossSpace	mySpace
protected PtrArray	mySteppers
protected Tuple	myValue
protected PtrArray	myVirginSteppers

Fields inherited from class org.abora.white.collection.steppers.Stepper

TheEmptyStepper

Constructor Summary

TupleStepper(CrossSpace space, PtrArray virginSteppers, PtrArray steppers, PrimIntArray lexOrder)

TupleStepper(Rcvr receiver)

Method Summary

Stepper	copy() Return a new stepper which steps independently of me, but whose current value is the same as mine, and which must produce a future history of values which satisfies the same obligation that my contract obligates me to produce now.
Heaper	fetch() If I am exhausted (i.e., if (!! this->hasValue())), then return NULL.
boolean	hasValue() Iff I have a current value (i.e.
static Stepper	make(CrossSpace space, PtrArray virginSteppers)
static Stepper	make(CrossSpace space, PtrArray virginSteppers, PrimIntArray lexOrder)
void	sendSelfTo(Xmtr xmtr)
void	setValueFromSteppers()
void	step() Essential.

Methods inherited from class org.abora.white.collection.steppers.Stepper

actualHashForEqual, atEnd, emptyStepper, get, info, isEqual, itemStepper, stepMany, stepMany, theOne

Methods inherited from class org.abora.white.xpp.basic.Heaper

destroy, destruct, equals, hashForEqual, printContentsOn, printOn, toString

Methods inherited from class java.lang.Object

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

Field Detail

mySpace

protected CrossSpace mySpace

myVirginSteppers

protected PtrArray myVirginSteppers

mySteppers

protected PtrArray mySteppers

myLexOrder

protected PrimIntArray myLexOrder

myValue

protected Tuple myValue

Constructor Detail

TupleStepper

public TupleStepper(CrossSpace space,
                    PtrArray virginSteppers,
                    PtrArray steppers,
                    PrimIntArray lexOrder)

TupleStepper

public TupleStepper(Rcvr receiver)

Method Detail

setValueFromSteppers

public void setValueFromSteppers()

copy

public Stepper copy()

Description copied from class: Stepper

Return a new stepper which steps independently of me, but whose current value is the same as mine, and which must produce a future history of values which satisfies the same obligation that my contract obligates me to produce now. Typically, this will mean that he must produce the same future history that I'm going to produce. However, let's say that I am enumerating the elements of a partial order in some full order which is consistent with the partial order. If a copy of me is made after I'm part way through, then me and my copy may produce any future history compatable both with the partial order and the elements I've already produced by the time of the copy. Of course, a subclass or a Stepper creating message (like IntegerRegion::stepper()) may specify the more stringent requirement (that a copy must produce the same sequence). To prevent aliasing, Steppers should typically be passed by copy. See class comment.

Specified by:

copy in class Stepper

fetch

public Heaper fetch()

Description copied from class: Stepper

If I am exhausted (i.e., if (!! this->hasValue())), then return NULL. Else return current element. I return wimpily since most items returned are held by collections. If I create a new object, I should cache it.

Specified by:

fetch in class Stepper

hasValue

public boolean hasValue()

Description copied from class: Stepper

Iff I have a current value (i.e. this message returns true), then I am not exhasted. 'fetch' and 'get' will both return this value, and I can be 'step'ped to my next state. As I am stepped, eventually I may become exhausted (the reverse of all the above), which is a permanent condition. Note that not all steppers have to be exhaustable. A Stepper which enumerates all primes is perfectly reasonable. Assuming otherwise will create infinite loops. See class comment.

Specified by:

hasValue in class Stepper

step

public void step()

Description copied from class: Stepper

Essential. If I am currently exhausted (see Stepper::hasValue()), then it is an error to step me. The result of doing so isn't currently specified (we probably should specify it to BLAST, but I know that the implementation doesn't currently live up to that spec). If I am not exhausted, then this advances me to my next state. If my current value (see Stepper::get()) was my final value, then I am now exhausted, otherwise my new current value is the next value.

Specified by:

step in class Stepper

sendSelfTo

public void sendSelfTo(Xmtr xmtr)

Overrides:

sendSelfTo in class Heaper

make

public static Stepper make(CrossSpace space,
                           PtrArray virginSteppers,
                           PrimIntArray lexOrder)

make

public static Stepper make(CrossSpace space,
                           PtrArray virginSteppers)