org.jpc.engine.prolog.driver

Class UniquePrologEngineDriver<T extends PrologEngine>

java.lang.Object

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

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

All Implemented Interfaces:

PrologEngineDriver<T>, PrologEngineFactory<T>

public abstract class UniquePrologEngineDriver<T extends PrologEngine>
extends AbstractPrologEngineDriver<T>

This class describes logic engines that are unique per process Instances can cache the logic engine when creating it

Author:

sergioc

Field Summary

Fields inherited from class org.jpc.engine.prolog.driver.AbstractPrologEngineDriver

JAVA_SIDE_EXCEPTION_SPECIFIER

Constructor Summary

Constructors

Constructor and Description
UniquePrologEngineDriver(EngineDescription engineDescription)
UniquePrologEngineDriver(EngineDescription engineDescription, JpcPreferences preferences)

Method Summary

Modifier and Type	Method and Description
protected T	createPrologEngine(PrologEngineFactory<T> basicFactory)
protected abstract Collection<DriverStateListener>	getListeners() To force descendant to re-implement this method properly.
boolean	isDisabled() Answers if the driver is disabled (cannot create a Prolog Engine session) or enabled.
protected abstract boolean	isInstanceRunning()

Methods inherited from class org.jpc.engine.prolog.driver.AbstractPrologEngineDriver

addStateListener, createPrologEngine, defaultBasicFactory, getDescription, getEngineDescription, getLibraryName, getLicenseUrl, getPreferences, getShortDescription, getSiteUrl, notifyDisabledState, onCreate, readyOrThrow, removeStateListener, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

UniquePrologEngineDriver

public UniquePrologEngineDriver(EngineDescription engineDescription)

UniquePrologEngineDriver

public UniquePrologEngineDriver(EngineDescription engineDescription,
                                JpcPreferences preferences)

Method Detail

isDisabled

public boolean isDisabled()

Description copied from class: AbstractPrologEngineDriver

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>

Overrides:

isDisabled in class AbstractPrologEngineDriver<T extends PrologEngine>

Returns:

the disabled state of the driver

isInstanceRunning

protected abstract boolean isInstanceRunning()

createPrologEngine

protected T createPrologEngine(PrologEngineFactory<T> basicFactory)

Overrides:

createPrologEngine in class AbstractPrologEngineDriver<T extends PrologEngine>

getListeners

protected abstract Collection<DriverStateListener> getListeners()

To force descendant to re-implement this method properly. Since descendants represent drivers that can create only one session per JVM, descendant drivers should refer to the same collection of listeners.

Overrides:

getListeners in class AbstractPrologEngineDriver<T extends PrologEngine>

Returns:

the state listeners of this driver