org.jpc.engine.prolog.driver

Class AbstractPrologEngineDriver<T extends PrologEngine>

java.lang.Object

org.jpc.engine.prolog.driver.AbstractPrologEngineDriver<T>

All Implemented Interfaces:

PrologEngineDriver<T>, PrologEngineFactory<T>

Direct Known Subclasses:

JpcEngineDriver, UniquePrologEngineDriver

public abstract class AbstractPrologEngineDriver<T extends PrologEngine>
extends Object
implements PrologEngineDriver<T>

Field Summary

Fields

Modifier and Type	Field and Description
static String	JAVA_SIDE_EXCEPTION_SPECIFIER

Constructor Summary

Constructors

Constructor and Description
AbstractPrologEngineDriver(EngineDescription engineDescription)
AbstractPrologEngineDriver(EngineDescription engineDescription, JpcPreferences preferences) A PrologDriver may be instantiated with incomplete information.

Method Summary

Modifier and Type	Method and Description
void	addStateListener(DriverStateListener listener)
T	createPrologEngine()
protected T	createPrologEngine(PrologEngineFactory<T> basicFactory)
protected abstract PrologEngineFactory<T>	defaultBasicFactory()
String	getDescription()
EngineDescription	getEngineDescription()
abstract String	getLibraryName()
String	getLicenseUrl()
protected Collection<DriverStateListener>	getListeners() Subclasses may override this method to provide a convenient representation of the state listeners.
JpcPreferences	getPreferences()
String	getShortDescription()
String	getSiteUrl()
boolean	isDisabled() Answers if the driver is disabled (cannot create a Prolog Engine session) or enabled.
protected void	notifyDisabledState() Notify the listeners that the state of this driver is now disabled
protected void	onCreate(PrologEngine prologEngine) Invoked immediately after a Prolog engine abstraction has been created.
protected void	readyOrThrow()
void	removeStateListener(DriverStateListener listener)
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

JAVA_SIDE_EXCEPTION_SPECIFIER

public static final String JAVA_SIDE_EXCEPTION_SPECIFIER

See Also:

Constant Field Values

Constructor Detail

AbstractPrologEngineDriver

public AbstractPrologEngineDriver(EngineDescription engineDescription)

AbstractPrologEngineDriver

public AbstractPrologEngineDriver(EngineDescription engineDescription,
                                  JpcPreferences preferences)

A PrologDriver may be instantiated with incomplete information. This is with the intention to allow this data to be added later (e.g., with a GUI)

Parameters:

preferences -

Method Detail

getPreferences

public JpcPreferences getPreferences()

isDisabled

public boolean isDisabled()

Answers if the driver is disabled (cannot create a Prolog Engine session) or enabled. Normally this property cannot be set by the programmer but depends on the internals of the concrete driver implementation (that is the reason is not implemented as an instance variable). The original motivation of this property is to enable GUI tools to show properly the driver description and availability on the screen Normally, drivers supporting multiple Prolog engines are always enable. However, drivers supporting only one Prolog session are enabled only before creating the first (and unique) Prolog session, and disabled afterwards. Note that certain libraries (e.g., JPL) allows only one session using the library, so it is not possible to start a second session with a different Prolog engine that uses the same library. For example, if a SWI Prolog engine is created using JPL, it is not going to be possible to create a YAP Prolog engine using also JPL.

Specified by:

isDisabled in interface PrologEngineDriver<T extends PrologEngine>

Returns:

the disabled state of the driver

defaultBasicFactory

protected abstract PrologEngineFactory<T> defaultBasicFactory()

createPrologEngine

public final T createPrologEngine()

Specified by:

createPrologEngine in interface PrologEngineFactory<T extends PrologEngine>

Returns:

a Prolog engine.

createPrologEngine

protected T createPrologEngine(PrologEngineFactory<T> basicFactory)

readyOrThrow

protected void readyOrThrow()

onCreate

protected void onCreate(PrologEngine prologEngine)

Invoked immediately after a Prolog engine abstraction has been created. This method is the right place for loading libraries required for the driver to function correctly in a concrete local engine. Driver implementors should note that this is a bootstrapping method and not all the services are available yet. Concretely, the jpc.pl file has not been loaded yet.

Parameters:

prologEngine -

notifyDisabledState

protected void notifyDisabledState()

Notify the listeners that the state of this driver is now disabled

addStateListener

public void addStateListener(DriverStateListener listener)

Specified by:

addStateListener in interface PrologEngineDriver<T extends PrologEngine>

removeStateListener

public void removeStateListener(DriverStateListener listener)

Specified by:

removeStateListener in interface PrologEngineDriver<T extends PrologEngine>

getListeners

protected Collection<DriverStateListener> getListeners()

Subclasses may override this method to provide a convenient representation of the state listeners. Concretely, drivers using libraries that can be instantiated only once, may implement this method as returning a static shared variable (care should be taken since this may pose a problem if the driver class is loaded by multiple classloaders).

Returns:

the state listeners of this driver

toString

public String toString()

Overrides:

toString in class Object

getShortDescription

public String getShortDescription()

Specified by:

getShortDescription in interface PrologEngineDriver<T extends PrologEngine>

getDescription

public String getDescription()

Specified by:

getDescription in interface PrologEngineDriver<T extends PrologEngine>

getLibraryName

public abstract String getLibraryName()

Specified by:

getLibraryName in interface PrologEngineDriver<T extends PrologEngine>

getEngineDescription

public EngineDescription getEngineDescription()

Specified by:

getEngineDescription in interface PrologEngineDriver<T extends PrologEngine>

getLicenseUrl

public String getLicenseUrl()

Specified by:

getLicenseUrl in interface PrologEngineDriver<T extends PrologEngine>

getSiteUrl

public String getSiteUrl()

Specified by:

getSiteUrl in interface PrologEngineDriver<T extends PrologEngine>