jess
Class Rete

java.lang.Object
  jess.Rete

All Implemented Interfaces:

java.util.EventListener, JessListener, java.io.Serializable

public class Rete

extends java.lang.Object

implements java.io.Serializable, JessListener

The reasoning engine and the central class in the Jess library. Executes the built Rete network, and coordinates many other activities. Rete is basically a facade for all the other classes in the Jess.

(C) 2003 Ernest J. Friedman-Hill and Sandia National Laboratories
$Id: Rete.java,v 1.23.2.1 2003/05/07 18:08:15 ejfried Exp $

See Also:

Serialized Form

Field Summary

static int	ACTIVATE
static int	EVERY_TIME
static int	INSTALL

Constructor Summary

Rete()

Rete(java.applet.Applet applet)

Rete(java.lang.Object appObject)

Method Summary

protected void	aboutToFire(Activation a)
Deffacts	addDeffacts(Deffacts df) Creates a new deffacts in this object
Defglobal	addDefglobal(Defglobal dg) Creates a new Defglobal in this object.
void	addDefmodule(java.lang.String moduleName) Define a new module, which becomes current.
void	addDefmodule(java.lang.String moduleName, java.lang.String doccomment) Define a new module, which becomes current.
HasLHS	addDefrule(HasLHS dr) Creates a new defrule or defquery in this object
Deftemplate	addDeftemplate(Deftemplate dt) Creates a new deftemplate in this object.
void	addInputRouter(java.lang.String s, java.io.Reader is, boolean consoleLike)
void	addJessListener(JessListener jel)
void	addOutputRouter(java.lang.String s, java.io.Writer os)
Userfunction	addUserfunction(Userfunction uf) Creates a new function in this object Will happily destroy an old one.
Userpackage	addUserpackage(Userpackage up) Add a Userpackage to this engine.
Fact	assert(Fact f) Deprecated. Use assertFact instead.
Fact	assert(Fact f, Context c) Deprecated. Use assertFact instead
Fact	assertFact(Fact f) Assert a fact
Fact	assertFact(Fact f, Context c) Assert a fact
Fact	assertString(java.lang.String s) Assert a fact, as a String, using the global execution context
Fact	assertString(java.lang.String s, Context c) Assert a fact, as a String
void	bload(java.io.InputStream is) Read this object's state from the given stream.
void	bsave(java.io.OutputStream os) Save this object's state out to the given stream.
void	clear() Reinitialize engine Thanks to Karl Mueller for idea
void	clearFocusStack() Empty the focus stack.
void	clearStorage() Clear the storage used by store() and fetch().
Value	defclass(java.lang.String jessName, java.lang.String clazz, java.lang.String parent) Add a defclass definition to this engine
Value	definstance(java.lang.String jessTypename, java.lang.Object object, boolean dynamic) Tell this engine to pattern match on the given object.
Value	definstance(java.lang.String jessTypename, java.lang.Object object, boolean dynamic, Context context)
int	doPreAssertionProcessing(Fact f)
void	eventHappened(JessEvent je) This method is just an implementation detail.
Value	executeCommand(java.lang.String cmd) Evaluate a Jess expression in this engine's global context.
Value	executeCommand(java.lang.String cmd, Context context) Evaluate a Jess expression in the given context.
Value	fetch(java.lang.String name) Retrieve an object previously stored with store().
java.lang.Class	findClass(java.lang.String clazz)
Deffacts	findDeffacts(java.lang.String name) Return the named deffacts object
Defglobal	findDefglobal(java.lang.String name) Look up a defglobal by name.
HasLHS	findDefrule(java.lang.String name) Find a defrule or defquery object with a certain name.
Deftemplate	findDeftemplate(java.lang.String name) Find a deftemplate object with a certain name
Fact	findFactByFact(Fact f) This find is fast, and can be used to find out quickly if a given fact is on the fact-list and if so, obtain a reference to it.
Fact	findFactByID(int id) This "find" is very slow; don't use it unless you have to.
Userfunction	findUserfunction(java.lang.String name) Find a userfunction, if there is one.
java.lang.Object	getActivationSemaphore() The monitor of the object returned from this method will be signalled whenever an activation appears.
java.applet.Applet	getApplet() Returns the applet this Rete is installed in.
java.lang.Class	getAppObjectClass() Returns the "application object" for this Rete instance
java.lang.String	getCurrentModule() Return the name of the current module.
java.io.PrintWriter	getErrStream()
int	getEvalSalience() Fetch the salience evaluation behaviour
int	getEventMask()
static Factory	getFactory()
java.lang.String	getFocus() Query the focus module.
Context	getGlobalContext() Fetch the global execution context.
boolean	getInputMode(java.lang.String s)
java.io.Reader	getInputRouter(java.lang.String s)
java.io.Writer	getOutputRouter(java.lang.String s)
java.io.PrintWriter	getOutStream()
boolean	getResetGlobals() When resetGlobals is true, the initializers of global variables are evaluated when (reset) is executed.
Strategy	getStrategy() Retrieve the Strategy object this engine is using to order activations on the agenda.
java.util.ArrayList	getSupportedFacts(Fact supporter) Returns a list of Fact objects that receive logical support from the argument.
java.util.ArrayList	getSupportingTokens(Fact fact) Returns a list of one or more jess.Token objects that provide logical support for this fact.
Activation	getThisActivation() Get the activation record for the currently firing rule.
java.lang.String	getThisRuleName() Find out the name of the currently firing rule.
void	halt() Stop the engine from firing rules.
void	importClass(java.lang.String clazz)
void	importPackage(java.lang.String pack)
java.lang.Class	javaClassForDefclass(java.lang.String name) Return the Java Class corresponding to a given Defclass name, or null if the name was not found.
protected void	justFired(Activation a)
java.util.Iterator	listActivations() Return an Iterator over all the activiations for the current module.
java.util.Iterator	listActivations(java.lang.String moduleName) Return an Iterator over all the activiations for the named module.
java.util.Iterator	listDefclasses() Return an Iterator over all the names of all defclasses.
java.util.Iterator	listDeffacts() Return an Iterator over all the deffacts in this engine.
java.util.Iterator	listDefglobals() Return an Iterator over all the defglobals in this engine.
java.util.Iterator	listDefinstances() Return an Iterator over all the definstanced objects
java.util.Iterator	listDefrules() Return an Iterator over all the defrules in this engine.
java.util.Iterator	listDeftemplates() Return an Iterator over all the deftemplates in this engine, both explicit and implied.
java.util.Iterator	listFacts() Return an Iterator over all the facts currently on the fact-list
java.util.Iterator	listFocusStack() Iterate over the focus stack, from bottom to top.
java.util.Iterator	listFunctions() Return an Iterator over all the functions in this engine: built-in, user, and deffunctions.
java.util.Iterator	listJessListeners()
java.util.Iterator	listModules() List all modules
Fact	modify(Fact fact, java.lang.String slot, Value value) Modify a single slot in a fact.
Fact	modify(Fact fact, java.lang.String slot, Value value, Context context) Modify a single slot in a fact.
java.lang.String	popFocus(java.lang.String expected) Remove the top module from the focus stack, and return it.
void	ppFacts(java.lang.String head, java.io.Writer output) Write the pretty print forms of the facts with the given head to the writer
void	ppFacts(java.io.Writer output) Write the pretty print forms of all facts to the writer
void	removeInputRouter(java.lang.String s)
void	removeJessListener(JessListener jel)
void	removeOutputRouter(java.lang.String s)
void	reset() Reset the Rete engine.
java.lang.String	resolveName(java.lang.String name) Decorate the name with the current module name, if it doesn't already contain a module name.
Fact	retract(Fact f) Retract a fact.
Fact	retractString(java.lang.String s) Karl Mueller NASA/GSFC Code 522.2 (Karl.R.Mueller@gsfc.nasa.gov) 27.January.1998 Retract a fact as a string
int	run() Run the actual engine.
int	run(int max) Run the rule engine.
java.util.Iterator	runQuery(java.lang.String name, ValueVector params) Quick way to run a defquery
int	runUntilHalt() Run until halt() is called.
void	setApplet(java.applet.Applet applet) Associates this Rete with an applet so that, for instance, the (batch) commands will look for scripts using the applet's document base URL.
void	setAppObject(java.lang.Object appObject) Associates this Rete with an object so that, for instance, the (batch) commands will look for scripts using the object's class loader.
java.lang.String	setCurrentModule(java.lang.String name) Change the current module.
void	setEvalSalience(int method) Set the salience evaluation behaviour.
void	setEventMask(int i)
static void	setFactory(Factory f)
void	setFocus(java.lang.String name) Change the focus module.
void	setPendingFact(Fact fact, boolean assrt)
void	setResetGlobals(boolean reset) When resetGlobals is true, the initializers of global variables are evaluated when (reset) is executed.
java.lang.String	setStrategy(Strategy s) Tell this engine to use the given Strategy object to order the rules on the agenda.
Value	store(java.lang.String name, java.lang.Object val) Store a value in the engine under a given name for later retrieval by fetch.
Value	store(java.lang.String name, Value val) Store a value in the engine under a given name for later retrieval by fetch.
java.lang.String	toString()
Fact	undefinstance(java.lang.Object object) Tell this engine to stop pattern matching on the given object
Value	unDefrule(java.lang.String name) Remove a rule or query from this Rete object.
void	unwatch(int which) Cancel some debugging information.
void	unwatchAll() Cancel all debugging info.
Value	updateObject(java.lang.Object object) Bring a shadow fact up to date.
void	verifyModule(java.lang.String moduleName) Throw an exception if the argument isn't the name of a module.
void	waitForActivations() Waits on the activation lock until a rule is activated.
void	watch(int which) Produce some debugging information.
void	watchAll() Produce all possible debugging info.

Methods inherited from class java.lang.Object

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

Field Detail

INSTALL

public static final int INSTALL

See Also:

Constant Field Values

ACTIVATE

public static final int ACTIVATE

See Also:

Constant Field Values

EVERY_TIME

public static final int EVERY_TIME

See Also:

Constant Field Values

Constructor Detail

Rete

public Rete()

Rete

public Rete(java.applet.Applet applet)

Parameters:

applet - If this Rete object is being created inside an applet, pass it as an argument.

Rete

public Rete(java.lang.Object appObject)

Method Detail

addInputRouter

public void addInputRouter(java.lang.String s,
                           java.io.Reader is,
                           boolean consoleLike)

Parameters:

s - The router name

is - A Reader where the router's data comes from

consoleLike - See the Jess manual

removeInputRouter

public void removeInputRouter(java.lang.String s)

Parameters:

s - The name of the router

getInputRouter

public java.io.Reader getInputRouter(java.lang.String s)

Parameters:

s - The router name

Returns:

The router, or null if none

addOutputRouter

public void addOutputRouter(java.lang.String s,
                            java.io.Writer os)

Parameters:

s - The router name

os - Where the data should go

removeOutputRouter

public void removeOutputRouter(java.lang.String s)

Parameters:

s - The name of the router

getInputMode

public boolean getInputMode(java.lang.String s)

Parameters:

s - The router name

Returns:

The console-like property for that router

getOutputRouter

public java.io.Writer getOutputRouter(java.lang.String s)

Parameters:

s - The router name

Returns:

The router, or null if none

getErrStream

public java.io.PrintWriter getErrStream()

Returns:

The WSTDERR router

getOutStream

public java.io.PrintWriter getOutStream()

Returns:

The WSTDOUT router

doPreAssertionProcessing

public int doPreAssertionProcessing(Fact f)
                             throws JessException

Throws:

JessException

clear

public void clear()
           throws JessException

Reinitialize engine Thanks to Karl Mueller for idea

Throws:

JessException

setPendingFact

public void setPendingFact(Fact fact,
                           boolean assrt)

reset

public void reset()
           throws JessException

Reset the Rete engine. Remove all facts, activations, etc. Clear all non-globals from the global scope. Assert (initial-fact). Broadcasts a JessEvent of type RESET.

Throws:

JessException - If anything goes wrong.

assertString

public Fact assertString(java.lang.String s,
                         Context c)
                  throws JessException

Assert a fact, as a String

Parameters:

s - A String representing a fact

c - An execution context for resolving variables

Returns:

The fact that was asserted

Throws:

JessException - If something goes wrong

assertString

public Fact assertString(java.lang.String s)
                  throws JessException

Assert a fact, as a String, using the global execution context

Parameters:

s - A String representing a fact

Returns:

The fact that was asserted

Throws:

JessException - If something goes wrong

assert

public Fact assert(Fact f)
            throws JessException

Deprecated. Use assertFact instead.

Throws:

JessException

assertFact

public Fact assertFact(Fact f)
                throws JessException

Assert a fact

Parameters:

f - A Fact object. This fact becomes the property of Jess after calling assertFact() -- don't change any of its fields until the fact is retracted!

Returns:

The fact ID on success, or -1.

Throws:

JessException - If anything goes wrong

assert

public Fact assert(Fact f,
                   Context c)
            throws JessException

Deprecated. Use assertFact instead

Throws:

JessException

assertFact

public Fact assertFact(Fact f,
                       Context c)
                throws JessException

Assert a fact

Parameters:

f - A Fact object. This fact becomes the property of Jess after calling assertFact() -- don't change any of its fields until the fact is retracted!

Returns:

The fact ID on success, or -1.

Throws:

JessException - If anything goes wrong

retractString

public Fact retractString(java.lang.String s)
                   throws JessException

Karl Mueller NASA/GSFC Code 522.2 (Karl.R.Mueller@gsfc.nasa.gov) 27.January.1998 Retract a fact as a string

Parameters:

s -

Throws:

JessException

retract

public Fact retract(Fact f)
             throws JessException

Retract a fact.

Parameters:

f - A Fact object. Doesn't need to be the actual object that appears on the fact-list; can just be a Fact that could compare equal to one.

Throws:

JessException - If anything goes wrong.

modify

public Fact modify(Fact fact,
                   java.lang.String slot,
                   Value value)
            throws JessException

Modify a single slot in a fact. This function works for both plain and shadow facts.

Parameters:

fact - A fact that's currently in working memory.

slot - The name of a slot in the fact

value - A new value for the slot

Returns:

The fact argument

Throws:

JessException - If the slot name is bad or any other error occurs.

modify

public Fact modify(Fact fact,
                   java.lang.String slot,
                   Value value,
                   Context context)
            throws JessException

Modify a single slot in a fact. This function works for both plain and shadow facts.

Parameters:

fact - A fact that's currently in working memory.

slot - The name of a slot in the fact

value - A new value for the slot

context - The execution context

Returns:

The fact argument

Throws:

JessException - If the slot name is bad or any other error occurs.

findFactByID

public Fact findFactByID(int id)
                  throws JessException

This "find" is very slow; don't use it unless you have to. Consider the returned Fact to be READ-ONLY!

Parameters:

id - The fact-id

Returns:

The fact, or null if none

Throws:

JessException - If something goes wrong

findFactByFact

public Fact findFactByFact(Fact f)
                    throws JessException

This find is fast, and can be used to find out quickly if a given fact is on the fact-list and if so, obtain a reference to it. The argument doesn't have to be a fact on the fact list -- only a Fact object identical to one that is.

Throws:

JessException

ppFacts

public void ppFacts(java.lang.String head,
                    java.io.Writer output)
             throws java.io.IOException

Write the pretty print forms of the facts with the given head to the writer

Throws:

java.io.IOException

ppFacts

public void ppFacts(java.io.Writer output)
             throws java.io.IOException

Write the pretty print forms of all facts to the writer

Throws:

java.io.IOException

listDeffacts

public java.util.Iterator listDeffacts()

Return an Iterator over all the deffacts in this engine.

findDeffacts

public Deffacts findDeffacts(java.lang.String name)

Return the named deffacts object

listDeftemplates

public java.util.Iterator listDeftemplates()

Return an Iterator over all the deftemplates in this engine, both explicit and implied.

listDefrules

public java.util.Iterator listDefrules()

Return an Iterator over all the defrules in this engine.

listFacts

public java.util.Iterator listFacts()

Return an Iterator over all the facts currently on the fact-list

listDefinstances

public java.util.Iterator listDefinstances()

Return an Iterator over all the definstanced objects

listDefclasses

public java.util.Iterator listDefclasses()

Return an Iterator over all the names of all defclasses. You can use each name to look up the corresponding template using findDeftemplate, or the corresponding Java class using javaClassForDefclass.

See Also:

findDeftemplate(java.lang.String), javaClassForDefclass(java.lang.String)

listDefglobals

public java.util.Iterator listDefglobals()

Return an Iterator over all the defglobals in this engine.

listFunctions

public java.util.Iterator listFunctions()

Return an Iterator over all the functions in this engine: built-in, user, and deffunctions.

findDefrule

public final HasLHS findDefrule(java.lang.String name)

Find a defrule or defquery object with a certain name.

Parameters:

name - The name

Returns:

The found rule or query, or null.

javaClassForDefclass

public java.lang.Class javaClassForDefclass(java.lang.String name)

Return the Java Class corresponding to a given Defclass name, or null if the name was not found.

findDeftemplate

public Deftemplate findDeftemplate(java.lang.String name)
                            throws JessException

Find a deftemplate object with a certain name

Parameters:

name - The name

Returns:

The found object, or null.

Throws:

JessException

addDeftemplate

public Deftemplate addDeftemplate(Deftemplate dt)
                           throws JessException

Creates a new deftemplate in this object. Ensure that every deftemplate has a unique class name.

Parameters:

dt -

Returns:

The argument.

Throws:

JessException - If the deftemplate is already defined

addDeffacts

public Deffacts addDeffacts(Deffacts df)
                     throws JessException

Creates a new deffacts in this object

Parameters:

df - A new Deffacts object

Returns:

The argument

Throws:

JessException - If an error occurs during event broadcasting

addDefglobal

public Defglobal addDefglobal(Defglobal dg)
                       throws JessException

Creates a new Defglobal in this object. Trick it into resetting right now, regardless of the setting of resetGlobals.

Parameters:

dg - A new Defglobal object

Returns:

The argument

Throws:

JessException - If an error occurs

findDefglobal

public Defglobal findDefglobal(java.lang.String name)

Look up a defglobal by name.

Parameters:

name - The name of the defglobal

Returns:

The Defglobal, if found, or null.

addUserfunction

public Userfunction addUserfunction(Userfunction uf)

Creates a new function in this object Will happily destroy an old one.

Parameters:

uf - A new USerfunction

Returns:

The parameter, or null if call rejected by event handler

addUserpackage

public Userpackage addUserpackage(Userpackage up)

Add a Userpackage to this engine. A package generally calls addUserfunction lots of times.

Parameters:

up - The package object

Returns:

The package object, or null if call rejected by event handler

findUserfunction

public final Userfunction findUserfunction(java.lang.String name)

Find a userfunction, if there is one.

Parameters:

name - The name of the function

Returns:

The Userfunction object, if there is one.

addDefrule

public final HasLHS addDefrule(HasLHS dr)
                        throws JessException

Creates a new defrule or defquery in this object

Parameters:

dr - A Defrule or Defquery

Returns:

The added object

Throws:

JessException - If anything goes wrong.

unDefrule

public final Value unDefrule(java.lang.String name)
                      throws JessException

Remove a rule or query from this Rete object. Removes all subrules of the names rule as well.

Parameters:

name - The name of the rule or query

Returns:

The symbol TRUE

Throws:

JessException - If anything goes wrong

addDefmodule

public void addDefmodule(java.lang.String moduleName)
                  throws JessException

Define a new module, which becomes current.

Throws:

JessException

addDefmodule

public void addDefmodule(java.lang.String moduleName,
                         java.lang.String doccomment)
                  throws JessException

Define a new module, which becomes current.

Throws:

JessException

getCurrentModule

public java.lang.String getCurrentModule()

Return the name of the current module.

setCurrentModule

public java.lang.String setCurrentModule(java.lang.String name)
                                  throws JessException

Change the current module.

Throws:

JessException

listModules

public java.util.Iterator listModules()
                               throws JessException

List all modules

Throws:

JessException

getFocus

public java.lang.String getFocus()

Query the focus module.

setFocus

public void setFocus(java.lang.String name)
              throws JessException

Change the focus module.

Throws:

JessException

listFocusStack

public java.util.Iterator listFocusStack()
                                  throws JessException

Iterate over the focus stack, from bottom to top. The current focus module is returned last.

Throws:

JessException

clearFocusStack

public void clearFocusStack()

Empty the focus stack.

popFocus

public java.lang.String popFocus(java.lang.String expected)
                          throws JessException

Remove the top module from the focus stack, and return it. If expected in non-null, then this is a no-op unless expected names the top module on the stack.

Throws:

JessException

verifyModule

public void verifyModule(java.lang.String moduleName)
                  throws JessException

Throw an exception if the argument isn't the name of a module.

Throws:

JessException

resolveName

public java.lang.String resolveName(java.lang.String name)

Decorate the name with the current module name, if it doesn't already contain a module name.

listActivations

public java.util.Iterator listActivations()

Return an Iterator over all the activiations for the current module. Note that some of the activations may be cancelled or already fired; check the return value of "isInactive()"for each one to be sure.

listActivations

public java.util.Iterator listActivations(java.lang.String moduleName)
                                   throws JessException

Return an Iterator over all the activiations for the named module. Asterisk ("*") is not accepted. Note that some of the activations may be cancelled or already fired; check the return value of "isInactive()" for each one to be sure.

Returns:

An iterator over the agenda for the named module

Throws:

JessException

See Also:

Activation.isInactive()

getActivationSemaphore

public java.lang.Object getActivationSemaphore()

The monitor of the object returned from this method will be signalled whenever an activation appears. Thus a run-loop could wait on this monitor when idle.

Returns:

The activation lock

See Also:

waitForActivations()

waitForActivations

public void waitForActivations()

Waits on the activation lock until a rule is activated. Can be called in a run-loop to wait for more rules to fire.

See Also:

getActivationSemaphore()

setStrategy

public java.lang.String setStrategy(Strategy s)
                             throws JessException

Tell this engine to use the given Strategy object to order the rules on the agenda.

Parameters:

s - The new conflict resolution strategy

Returns:

The name of the previous conflict resolution strategy

Throws:

JessException

getStrategy

public Strategy getStrategy()

Retrieve the Strategy object this engine is using to order activations on the agenda.

Returns:

The current conflict resolution strategy

setEvalSalience

public final void setEvalSalience(int method)
                           throws JessException

Set the salience evaluation behaviour. The behaviour can be one of INSTALL, ACTIVATE, or EVERY_TIME; the default is INSTALL. When the behaviour is INSTALL, a rule's salience is evulated once when the rule is compiled. If it is ACTIVATE, it is computed each time the rule is activated. If it is EVERY_TIME, salience evaluations are done for all rules each time the next rule on the agenda is to be chosen.

Parameters:

method - One of the acceptable values

Throws:

JessException - If something goes wrong

getEvalSalience

public final int getEvalSalience()

Fetch the salience evaluation behaviour

Returns:

The salience evaluation behaviour

See Also:

setEvalSalience(int)

run

public int run()
        throws JessException

Run the actual engine.

Returns:

The actual number of rules fired

Throws:

JessException - If anything goes wrong.

aboutToFire

protected void aboutToFire(Activation a)

justFired

protected void justFired(Activation a)

run

public int run(int max)
        throws JessException

Run the rule engine.

Parameters:

max - The maximum number of rules to fire

Returns:

The number of rules that fired

Throws:

JessException - If anything goes wrong.

runUntilHalt

public int runUntilHalt()
                 throws JessException

Run until halt() is called. When no rules are active, the calling Thread will be waiting on the activation semaphore.

Returns:

The number of rules that fired.

Throws:

JessException

halt

public void halt()
          throws JessException

Stop the engine from firing rules.

Throws:

JessException

getThisRuleName

public java.lang.String getThisRuleName()

Find out the name of the currently firing rule.

Returns:

The name of the rule that is currently firing, if this is called while a rule is firing; otherwise, returns null.

See Also:

getThisActivation()

getThisActivation

public Activation getThisActivation()

Get the activation record for the currently firing rule. An activation record contains a Defrule and the list of facts that made the rule active.

Returns:

The activation record for the rule that is currently firing, if this is called while a rule is firing; otherwise, returns null.

See Also:

getThisRuleName()

addJessListener

public void addJessListener(JessListener jel)

removeJessListener

public void removeJessListener(JessListener jel)

listJessListeners

public java.util.Iterator listJessListeners()

getEventMask

public int getEventMask()

setEventMask

public void setEventMask(int i)

bload

public void bload(java.io.InputStream is)
           throws java.io.IOException,
                  java.lang.ClassNotFoundException

Read this object's state from the given stream.

Throws:

java.io.IOException

java.lang.ClassNotFoundException

bsave

public void bsave(java.io.OutputStream os)
           throws java.io.IOException

Save this object's state out to the given stream.

Throws:

java.io.IOException

definstance

public Value definstance(java.lang.String jessTypename,
                         java.lang.Object object,
                         boolean dynamic)
                  throws JessException

Tell this engine to pattern match on the given object.

Parameters:

jessTypename - The name of a defclass

object - An object of the defclass's type

dynamic - true if PropertyChangeListeners should be used

Returns:

A FactIdValue containing the shadow fact for the object

Throws:

JessException

definstance

public Value definstance(java.lang.String jessTypename,
                         java.lang.Object object,
                         boolean dynamic,
                         Context context)
                  throws JessException

Throws:

JessException

undefinstance

public Fact undefinstance(java.lang.Object object)
                   throws JessException

Tell this engine to stop pattern matching on the given object

Parameters:

object - An object of the defclass's type

Throws:

JessException

updateObject

public Value updateObject(java.lang.Object object)
                   throws JessException

Bring a shadow fact up to date. If the properties of the given object, assumed to be a definstanced object, have changed, its corresponding shadow fact will be updated.

Parameters:

object - A previously definstanced object

Returns:

The shadow fact, as a FactIDValue

Throws:

JessException - If object isn't a definstanced object, or on error.

defclass

public Value defclass(java.lang.String jessName,
                      java.lang.String clazz,
                      java.lang.String parent)
               throws JessException

Add a defclass definition to this engine

Parameters:

jessName - The name Jess should use for this defclass

clazz - The name of the Java class

parent - If non-null, a parent deftemplate or defclass name

Throws:

JessException

getApplet

public java.applet.Applet getApplet()

Returns the applet this Rete is installed in. Returns null if none.

Returns:

The applet

getAppObjectClass

public java.lang.Class getAppObjectClass()

Returns the "application object" for this Rete instance

See Also:

Rete(java.lang.Object)

setApplet

public void setApplet(java.applet.Applet applet)

Associates this Rete with an applet so that, for instance, the (batch) commands will look for scripts using the applet's document base URL.

Parameters:

applet - The applet

setAppObject

public void setAppObject(java.lang.Object appObject)

Associates this Rete with an object so that, for instance, the (batch) commands will look for scripts using the object's class loader.

Parameters:

appObject - The app object

getGlobalContext

public final Context getGlobalContext()

Fetch the global execution context.

Returns:

The global execution context.

executeCommand

public Value executeCommand(java.lang.String cmd)
                     throws JessException

Evaluate a Jess expression in this engine's global context.

Parameters:

cmd - A string containing a Jess expression

Returns:

The result of evaluating the expression

Throws:

JessException - If anything goes wrong

executeCommand

public Value executeCommand(java.lang.String cmd,
                            Context context)
                     throws JessException

Evaluate a Jess expression in the given context.

Parameters:

cmd - A string containing a Jess expression

context - The evaluation context

Returns:

The result of evaluating the expression

Throws:

JessException - If anything goes wrong

setResetGlobals

public final void setResetGlobals(boolean reset)

When resetGlobals is true, the initializers of global variables are evaluated when (reset) is executed.

Parameters:

reset - The value of this property

getResetGlobals

public final boolean getResetGlobals()

When resetGlobals is true, the initializers of global variables are evaluated when (reset) is executed.

Returns:

The value of this property

store

public Value store(java.lang.String name,
                   Value val)

Store a value in the engine under a given name for later retrieval by fetch.

Parameters:

name - A key under which to file the value

val - The value to store

Returns:

Any old value stored under this name, or null.

See Also:

fetch(java.lang.String)

store

public Value store(java.lang.String name,
                   java.lang.Object val)

Store a value in the engine under a given name for later retrieval by fetch. The Object is first wrapped in a new jess.Value object.

Parameters:

name - A key under which to file the value

val - The value to store

Returns:

Any old value stored under this name, or null.

See Also:

fetch(java.lang.String)

fetch

public Value fetch(java.lang.String name)

Retrieve an object previously stored with store().

Parameters:

name - The key under which to find an object

Returns:

The object, or null if not found.

See Also:

store(java.lang.String, jess.Value)

clearStorage

public void clearStorage()

Clear the storage used by store() and fetch().

getFactory

public static Factory getFactory()

setFactory

public static void setFactory(Factory f)

findClass

public java.lang.Class findClass(java.lang.String clazz)
                          throws java.lang.ClassNotFoundException

Throws:

java.lang.ClassNotFoundException

importPackage

public void importPackage(java.lang.String pack)

importClass

public void importClass(java.lang.String clazz)

runQuery

public java.util.Iterator runQuery(java.lang.String name,
                                   ValueVector params)
                            throws JessException

Quick way to run a defquery

Throws:

JessException

watch

public void watch(int which)
           throws JessException

Produce some debugging information. The argument specifies which kind of event will be reported. The output goes to the "WSTDOUT" router.

Parameters:

which - One of the constants in WatchConstants

Throws:

JessException - If the argument is invalid

See Also:

WatchConstants

unwatch

public void unwatch(int which)
             throws JessException

Cancel some debugging information. The argument specifies which kind of event will no longer be reported.

Parameters:

which - One of the constants in WatchConstants

Throws:

JessException - If the argument is invalid

See Also:

WatchConstants

watchAll

public void watchAll()

Produce all possible debugging info. Equivalent to calling watch() multiple times using each legal argument in succession.

unwatchAll

public void unwatchAll()

Cancel all debugging info. Equivalent to calling unwatch() using each legal argument in succession.

eventHappened

public void eventHappened(JessEvent je)

This method is just an implementation detail. Part of the "watch" facility. Each Rete object is registered with itself as a listener.

Specified by:

eventHappened in interface JessListener

Parameters:

je - An event object

toString

public java.lang.String toString()

getSupportingTokens

public java.util.ArrayList getSupportingTokens(Fact fact)

Returns a list of one or more jess.Token objects that provide logical support for this fact. This method returns null if there is no specific logical support. You can use the Token.size() method to check how many supporting Facts are in a Token, and the Token.fact() method to check each supporting Fact in turn. This is a fast operation, taking O(ln N) time, where N is the number of facts that have logical support.

Parameters:

fact - A fact of interest.

Returns:

A list of supporting Token objects, or null if there is unconditional support.

See Also:

Token, Token.fact(int), Token.size()

getSupportedFacts

public java.util.ArrayList getSupportedFacts(Fact supporter)

Returns a list of Fact objects that receive logical support from the argument. This method is potentially expensive, as it takes time proportional to O(N), where N is the number of facts currently receiving logical support of any kind.

Parameters:

supporter - A fact of interest.

Returns:

A list of zero or more Fact objects.