agi.foundation.celestial

(agi.foundation.models-2024r2.jar)

Class JplDEFile

java.lang.Object

agi.foundation.infrastructure.DefinitionalObject

agi.foundation.celestial.JplDEFile

All Implemented Interfaces:

ICloneWithContext, IEnumerateDependencies, IEquatableDefinition, IFreezable

public class JplDEFile
extends DefinitionalObject

Provides raw access to a JPL DE file.

JPL Planetary Ephemeris files can be downloaded from https://ftp.agi.com/pub/STKData/Astro/PlanetEphem/lendian/.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	JplDEFile(JplDEFile existingInstance, CopyContext context) Initializes a new instance as a copy of an existing instance.
	JplDEFile(StreamFactory streamFactory) Initializes a new instance with the specified stream factory.
	JplDEFile(String fileName) Initializes an instance using the specified JPL DE filename.

Method Summary

Modifier and Type	Method and Description
protected boolean	checkForSameDefinition(DefinitionalObject other) Checks to determine if another instance has the same definition as this instance and returns true if it does.
protected boolean	checkForSameDefinition(JplDEFile 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.
Iterable<String>	getConstants() Gets an enumerator for the constants in the file.
double	getConstantValue(String name) Retrieves the value associated with the named constant.
double	getDaysPerBlock() Gets the number of days in each data block.
JplDEFileEvaluator	getEvaluator(JplDEDataIndex index) Gets an evaluator that can be used to produce the time-varying information based on this JPL DE file.
JplDEFileEvaluator	getEvaluator(JplDEDataIndex index, EvaluatorGroup group) Gets an evaluator that can be used to calculate time-varying information in the file.
JulianDate	getFinalEpoch() Gets the final epoch for which this file contains data.
JulianDate	getInitialEpoch() Gets the initial epoch for which this file contains data.
List<String>	getTitles() Gets the titles of this file.
static JulianDate	jedToJulianDate(double jed) Converts a Julian ephemeris date to a Julian epoch.
static double	julianDateToJed(JulianDate epoch) Converts a Julian epoch to a Julian ephemeris date.

Methods inherited from class agi.foundation.infrastructure.DefinitionalObject

areSameDefinition, areSameDefinition, areSameDefinition, areSameDefinition, areSameDefinition, collectionItemsAreSameDefinition, collectionItemsAreSameDefinition, collectionItemsAreSameDefinition, dictionaryItemsAreSameDefinition, enumerateDependencies, freeze, freezeAggregatedObjects, 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, toString, wait, wait, wait

Constructor Detail

JplDEFile

public JplDEFile(@Nonnull
                 String fileName)

Initializes an instance using the specified JPL DE filename.

Parameters:

fileName - The full path and filename of the JPL DE file.

Throws:

ArgumentNullException - Thrown when fileName is null.

JplDEFile

public JplDEFile(@Nonnull
                 StreamFactory streamFactory)

Initializes a new instance with the specified stream factory.

The streams created by streamFactory must support seeking. This means that the streams must implement ISeekableStream or FileInputStream.

Parameters:

streamFactory - The factory to use to create streams to read the JPL DE data.

Throws:

ArgumentNullException - Thrown when streamFactory is null.

JplDEFile

protected JplDEFile(@Nonnull
                    JplDEFile 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

Specified by:

clone in class DefinitionalObject

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(DefinitionalObject 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).

Specified by:

checkForSameDefinition in class DefinitionalObject

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(JplDEFile 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 JplDEFile.checkForSameDefinition(agi.foundation.infrastructure.DefinitionalObject) method.

Overrides:

computeCurrentDefinitionHashCode in class DefinitionalObject

Returns:

The computed hash code.

getConstantValue

public final double getConstantValue(@Nonnull
                                     String name)

Retrieves the value associated with the named constant.

Parameters:

name - The name of the constant to retrieve.

Returns:

The value of the constant with the specified name.

getConstants

public final Iterable<String> getConstants()

Gets an enumerator for the constants in the file.

getTitles

@Nonnull
public final List<String> getTitles()

Gets the titles of this file.

getInitialEpoch

@Nonnull
public final JulianDate getInitialEpoch()

Gets the initial epoch for which this file contains data.

getFinalEpoch

@Nonnull
public final JulianDate getFinalEpoch()

Gets the final epoch for which this file contains data.

getDaysPerBlock

public final double getDaysPerBlock()

Gets the number of days in each data block.

getEvaluator

@Nonnull
public final JplDEFileEvaluator getEvaluator(@Nonnull
                                                       JplDEDataIndex index)

Gets an evaluator that can be used to produce the time-varying information based on this JPL DE file. The evaluator will produce an array of double values corresponding to the data for the given JplDEDataIndex for a given JulianDate.

Parameters:

index - The index of the data to evaluate.

Returns:

An evaluator used to calculate time-varying information in the file.

getEvaluator

@Nonnull
public final JplDEFileEvaluator getEvaluator(@Nonnull
                                                       JplDEDataIndex index,
                                                       @Nonnull
                                                       EvaluatorGroup group)

Gets an evaluator that can be used to calculate time-varying information in the file.

Parameters:

index - The index of the data to evaluate.

group - The group with which to associate the new evaluator. By grouping evaluators that are often evaluated at the same Julian dates, common computations can be performed only once for the entire group instead of multiple times for each evaluator.

Returns:

An evaluator used to calculate time-varying information in the file.

Throws:

ArgumentNullException - Thrown when group is null.

jedToJulianDate

@Nonnull
public static JulianDate jedToJulianDate(double jed)

Converts a Julian ephemeris date to a Julian epoch.

Parameters:

jed - The Julian ephemeris date to convert.

Returns:

The corresponding Julian epoch in BarycentricDynamicalTime (get).

julianDateToJed

public static double julianDateToJed(@Nonnull
                                     JulianDate epoch)

Converts a Julian epoch to a Julian ephemeris date.

Parameters:

epoch - The Julian epoch to convert in BarycentricDynamicalTime (get).

Returns:

The corresponding Julian ephemeris date.