agi.foundation.segmentpropagation

(agi.foundation.segmentpropagation-2023r2.jar)

Class HoldSegment

java.lang.Object

agi.foundation.infrastructure.DefinitionalObject

agi.foundation.segmentpropagation.SegmentDefinition

agi.foundation.segmentpropagation.PropagateSegment

agi.foundation.segmentpropagation.HoldSegment

All Implemented Interfaces:

ICloneWithContext, IEnumerateDependencies, IEquatableDefinition, IFreezable

public class HoldSegment
extends PropagateSegment

A segment whose states are held constant in time. This is intended to be used when the object being propagated is fixed in some way, such as landed on a central body or fixed to another vehicle. The results returned when this segments propagator is propagated will always be a .

The advantage to using this derived type as opposed to the PropagateSegment directly is that the configuration of the StateElementAdapters is handled automatically.

Note that this segment implements PropagateSegment and as such at propagation time, it is possible to configure a ChangePropagateSegmentsPropagatorOperator with any other StoppablePropagatorDefinition.

Also note that this segment is unique in that StateElementAdapters are optional. If one is not set or specified for an element then no transformation will take place for that element.

Constructor Summary

Constructors

Modifier	Constructor and Description
	HoldSegment() Initializes a new instance.
protected	HoldSegment(HoldSegment existingInstance, CopyContext context) Initializes a new instance as a copy of an existing instance.

Method Summary

Modifier and Type	Method and Description
protected boolean	checkForSameDefinition(HoldSegment other) Checks to determine if another instance has the same definition as this instance and returns true if it does.
protected boolean	checkForSameDefinition(PropagateSegment other) Checks to determine if another instance has the same definition as this instance and returns true if it does.
Object	clone(CopyContext context) Clones this object using the specified context.
protected int	computeCurrentDefinitionHashCode() Computes a hash code based on the current properties of this object.
protected SegmentPropagator	createSegmentPropagator(EvaluatorGroup group, SegmentDefinition previousSegment) Creates, configures, and returns the SegmentPropagator for this segment.
protected boolean	getAllowZeroElements() Gets a value indicating whether if it is acceptable for this type of PropagateSegment to have no elements.
Duration	getStep() Gets the default step that the SegmentPropagator should creates states for.
void	setStep(Duration value) Sets the default step that the SegmentPropagator should creates states for.

Methods inherited from class agi.foundation.segmentpropagation.PropagateSegment

addPropagationFinishedEvent, addStepTaken, checkForSameDefinition, clearStoppingConditionsAutoSegment, enumerateDependencies, freezeAggregatedObjects, getMaximumDuration, getNumberOfTimesToExecuteStoppingConditionsAutoSegment, getOutputSparsity, getStopOnMaximumDurationBehavior, getStoppablePropagator, getStoppingConditions, getStoppingConditionsAutoSegment, removePropagationFinishedEvent, removeStepTaken, setMaximumDuration, setOutputSparsity, setStopOnMaximumDurationBehavior, setStoppablePropagator, setStoppingConditionAutoSegment

Methods inherited from class agi.foundation.segmentpropagation.SegmentDefinition

checkForSameDefinition, containsElement, getDefinedIn, getElementAdapter, getElements, getName, getNextStateBehavior, getPassAllElementsToNextSegment, getPropagationDirection, getSegmentPropagator, getSegmentPropagator, getSegmentPropagator, getSegmentPropagator, removeElement, setElementAndAdapter, setName, setNextStateBehavior, setPropagationDirection, toString

Methods inherited from class agi.foundation.infrastructure.DefinitionalObject

areSameDefinition, areSameDefinition, areSameDefinition, areSameDefinition, areSameDefinition, collectionItemsAreSameDefinition, collectionItemsAreSameDefinition, collectionItemsAreSameDefinition, dictionaryItemsAreSameDefinition, freeze, getCollectionHashCode, getCollectionHashCode, getCollectionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDictionaryHashCode, getIsFrozen, isSameDefinition, throwIfFrozen

Methods inherited from class java.lang.Object

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

Constructor Detail

HoldSegment

public HoldSegment()

Initializes a new instance. The Step (get / set) and at least one StoppingCondition must be added to the StoppingConditions (get) before the SegmentPropagator for this SegmentDefinition can be created.

HoldSegment

protected HoldSegment(@Nonnull
                      HoldSegment existingInstance,
                      @Nonnull
                      CopyContext context)

Initializes a new instance as a copy of an existing instance.

See ICloneWithContext.clone(CopyContext) for more information about how to implement this constructor in a derived class.

Parameters:

existingInstance - The existing instance to copy.

context - A CopyContext that controls the depth of the copy.

Throws:

ArgumentNullException - Thrown when existingInstance or context is null.

Method Detail

clone

public Object clone(CopyContext context)

Clones this object using the specified context.

This method should be implemented to call a copy constructor on the class of the object being cloned. The copy constructor should take the CopyContext as a parameter in addition to the existing instance to copy. The copy constructor should first call CopyContext.addObjectMapping(T, T) to identify the newly constructed instance as a copy of the existing instance. It should then copy all fields, using CopyContext.updateReference(T) to copy any reference fields.

A typical implementation of ICloneWithContext:

public static class MyClass implements ICloneWithContext {
    public MyClass(MyClass existingInstance, CopyContext context) {
        context.addObjectMapping(existingInstance, this);
        someReference = context.updateReference(existingInstance.someReference);
    }

    @Override
    public final Object clone(CopyContext context) {
        return new MyClass(this, context);
    }

    private Object someReference;
}

In general, all fields that are reference types should be copied with a call to CopyContext.updateReference(T). There are a couple of exceptions:

1. Fields that are aggregate parts of the object should always be copied. A referenced object is an aggregate if properties or methods on the object being copied can modify the externally-visible value of the referenced object.
2. If the semantics of the referenced object require that it have a single parent, owner, context, etc., and the object being copied is that parent, owner, or context, then the referenced object should always be copied.

If one of these exceptions applies, the CopyContext should be given an opportunity to update the reference before the reference is copied explicitly. Use CopyContext.updateReference(T) to update the reference. If CopyContext.updateReference(T) returns the original object, indicating that the context does not have a replacement registered, then copy the object manually by invoking a Clone method, a copy constructor, or by manually constructing a new instance and copying the values.

alwaysCopy = context.updateReference(existingInstance.alwaysCopy);
if (existingInstance.alwaysCopy != null && alwaysCopy == existingInstance.alwaysCopy) {
    alwaysCopy = (AlwaysCopy) existingInstance.alwaysCopy.clone(context);
}

If you are implementing an evaluator (a class that implements IEvaluator), the IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) method shares some responsibilities with the copy context constructor. Code duplication can be avoided by doing the following:

1. For references to other evaluators ONLY, simply assign the reference in the constructor instead of calling CopyContext.updateReference(T). You should still call CopyContext.updateReference(T) on any references to non-evaluators.
2. Call IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) as the last line in the constructor and pass it the same CopyContext passed to the constructor.
3. Implement IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) as normal. See the reference documentation for IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) for more information on implementing that method.

public MyClass(MyClass existingInstance, CopyContext context) {
    super(existingInstance, context);
    someReference = context.updateReference(existingInstance.someReference);
    evaluatorReference = existingInstance.evaluatorReference;
    updateEvaluatorReferences(context);
}

@Override
public void updateEvaluatorReferences(CopyContext context) {
    evaluatorReference = context.updateReference(evaluatorReference);
}

@Override
public Object clone(CopyContext context) {
    return new MyClass(this, context);
}

private Object someReference;
private IEvaluator evaluatorReference;

Specified by:

clone in interface ICloneWithContext

Overrides:

clone in class PropagateSegment

Parameters:

context - The context to use to perform the copy.

Returns:

A new instance which is a copy of this object.

checkForSameDefinition

protected final boolean checkForSameDefinition(PropagateSegment other)

Checks to determine if another instance has the same definition as this instance and returns true if it does. Derived classes MUST override this method and check all new fields introduced by the derived class for definitional equivalence. It is NOT necessary to check base class fields because the base class will already have done that. When overriding this method, you should NOT call the base implementation because it will return false for all derived-class instances. Derived classes should check the type of other to preserve the symmetric nature of IEquatableDefinition.isSameDefinition(java.lang.Object).

Overrides:

checkForSameDefinition in class PropagateSegment

Parameters:

other - The other instance to compare to this one.

Returns:

true if the two objects are defined equivalently; otherwise false.

checkForSameDefinition

protected boolean checkForSameDefinition(HoldSegment other)

Checks to determine if another instance has the same definition as this instance and returns true if it does. Derived classes MUST override this method and check all new fields introduced by the derived class for definitional equivalence. It is NOT necessary to check base class fields because the base class will already have done that. When overriding this method, you should NOT call the base implementation because it will return false for all derived-class instances. Derived classes should check the type of other to preserve the symmetric nature of IEquatableDefinition.isSameDefinition(java.lang.Object).

Parameters:

other - The other instance to compare to this one.

Returns:

true if the two objects are defined equivalently; otherwise false.

computeCurrentDefinitionHashCode

protected int computeCurrentDefinitionHashCode()

Computes a hash code based on the current properties of this object. Derived classes MUST override this method and compute a hash code that combines: a unique hash code seed, the base implementation result, and the hash codes of all new fields introduced by the derived class which are used in the HoldSegment.checkForSameDefinition(agi.foundation.segmentpropagation.PropagateSegment) method.

Overrides:

computeCurrentDefinitionHashCode in class PropagateSegment

Returns:

The computed hash code.

getAllowZeroElements

protected boolean getAllowZeroElements()

Gets a value indicating whether if it is acceptable for this type of PropagateSegment to have no elements. HoldSegment always returns true.

Overrides:

getAllowZeroElements in class PropagateSegment

getStep

@Nonnull
public final Duration getStep()

Gets the default step that the SegmentPropagator should creates states for.

setStep

public final void setStep(@Nonnull
                          Duration value)

Sets the default step that the SegmentPropagator should creates states for.

createSegmentPropagator

protected SegmentPropagator createSegmentPropagator(EvaluatorGroup group,
                                                    SegmentDefinition previousSegment)

Creates, configures, and returns the SegmentPropagator for this segment. This method should check that all of the required properties on the concrete instance are configured properly before constructing the SegmentPropagator to be returned.

Overrides:

createSegmentPropagator in class PropagateSegment

Parameters:

group - The group to use during creation.

previousSegment - The previous segment. Some segments will require the previousSegment to be set, whereas other will require that the previous segment not be null, whereas others will only use information from it if provided. It is up to you writing a concrete type to enforce what makes sense for your particular segment in this method.

Returns:

The propagator for this segment.