jess
Class Funcall

java.lang.Object
  jess.ValueVector
      jess.Funcall

All Implemented Interfaces:

java.lang.Cloneable, java.io.Serializable, Visitable

public class Funcall

extends ValueVector

implements java.io.Serializable, Visitable

jess.Funcall is a specialized subclass of ValueVector that represents a Jess function call. It contains the name of the function, an internal pointer to the actual Userfunction object containing the function code, and the arguments to pass to the function.

You can call Jess functions using Funcall if you prefer, rather than using Rete.eval(java.lang.String) This method has somewhat less overhead since there is no parsing to be done, but of course it's less convenient.

 Rete r = new Rete();

 // The following is equivalent to the Jess code
 // (defclass dimension "java.awt.Dimension")
 Funcall f = new Funcall("defclass", r);
 f.arg("dimension").arg("java.awt.Dimension");
 f.execute(r.getGlobalContext());
 

The first entry in a Funcall's ValueVector is the name of the function, even though you don't explicitly set it. Changing the first entry will not automatically change the function the Funcall will call! On the other hand, redefining a function in the Rete object a Funcall is tied to will cause the Funcall to call the new function.

The Funcall class also contains some public static constant Value member objects that represent the special symbols nil, TRUE, FALSE, EOF, etc. You are encouraged to use these.

(C) 2006 Sandia National Laboratories

See Also:

FuncallValue, Serialized Form

Field Summary

static Value	CRLF The object representing a newline to printout
static Value	EOF The object representing end-of-file
static Value	FALSE The object representing the value FALSE
static Value	NIL The object representing the value NIL
static Value	NILLIST An object representing an empty list.
static Value	T The object representing printout's standard router
static Value	TRUE The object representing the value TRUE

Fields inherited from class jess.ValueVector

m_ptr, m_v

Constructor Summary

Funcall(java.lang.String name, Rete engine)
Create a Funcall given the name.

Method Summary

java.lang.Object	accept(Visitor v) A proper accept() implementation should call one of the visitXXX() methods on the Visitor.
Funcall	arg(double f) Calls ValueVector.add(jess.Value), then returns this object.
Funcall	arg(Funcall f) Calls ValueVector.add(jess.Value), then returns this object.
Funcall	arg(int i) Calls ValueVector.add(jess.Value), then returns this object.
Funcall	arg(long l) Calls ValueVector.add(jess.Value), then returns this object.
Funcall	arg(java.lang.Object o) Calls ValueVector.add(jess.Value), then returns this object.
Funcall	arg(java.lang.String s) Calls ValueVector.add(jess.Value), then returns this object.
Funcall	arg(Value v) Calls ValueVector.add(jess.Value), then returns this object.
java.lang.Object	clone() Copies a Funcall
Funcall	cloneInto(Funcall vv) Makes the argument into a copy of this Funcall.
Value	execute(Context context) Execute this funcall in a particular context.
Value	get(int i) A version of ValueVector.get with more appropriate error messages.
java.lang.String	getName() Returns the name of the function this Funcall will invoke
Userfunction	getUserfunction(Rete engine) Returns the Userfunction object this Funcall would invoke if it were invoked now,
static java.util.Iterator	listIntrinsics() Lists all the functions built into this version of Jess.
java.lang.String	toString() Formats a Funcall as a String
java.lang.String	toStringWithParens() Just calls toString()

Methods inherited from class jess.ValueVector

add, add, add, add, add, add, add, addAll, addAll, cloneInto, copy, equals, hashCode, remove, set, setLength, size

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

TRUE

public static Value TRUE

The object representing the value TRUE

FALSE

public static Value FALSE

The object representing the value FALSE

NIL

public static Value NIL

The object representing the value NIL

NILLIST

public static Value NILLIST

An object representing an empty list.

EOF

public static Value EOF

The object representing end-of-file

CRLF

public static Value CRLF

The object representing a newline to printout

T

public static Value T

The object representing printout's standard router

Constructor Detail

Funcall

public Funcall(java.lang.String name,
               Rete engine)
        throws JessException

Create a Funcall given the name. The Funcall's arguments must then be added using methods inherited from ValueVector.

Parameters:

name - The name of the function

engine - The Rete engine where the function is defined

Throws:

JessException - If something goes wrong.

Method Detail

toString

public java.lang.String toString()

Formats a Funcall as a String

Overrides:

toString in class ValueVector

Returns:

The pretty-print form of this Funcall

toStringWithParens

public java.lang.String toStringWithParens()

Just calls toString()

Overrides:

toStringWithParens in class ValueVector

Returns:

the pretty-print form of this Funcall

listIntrinsics

public static java.util.Iterator listIntrinsics()

Lists all the functions built into this version of Jess.

Returns:

the Iterator

getName

public java.lang.String getName()

Returns the name of the function this Funcall will invoke

Returns:

the name of the function

clone

public java.lang.Object clone()

Copies a Funcall

Overrides:

clone in class ValueVector

Returns:

A copy of the Funcall

cloneInto

public Funcall cloneInto(Funcall vv)

Makes the argument into a copy of this Funcall.

Parameters:

vv - The Funcall into which the copy should be made

Returns:

The argument

execute

public Value execute(Context context)
              throws JessException

Execute this funcall in a particular context.

Parameters:

context - An execution context for the function

Returns:

The result of the function call

Throws:

JessException - If something goes wrong

getUserfunction

public Userfunction getUserfunction(Rete engine)
                             throws JessException

Returns the Userfunction object this Funcall would invoke if it were invoked now,

Parameters:

engine - the Rete object that will supply the execution context

Returns:

the Userfunction object

Throws:

JessException

arg

public Funcall arg(Value v)

Calls ValueVector.add(jess.Value), then returns this object. This method does the same thing as add but returns this Funcall as a Funcall so the last call in a chain can be a call to execute(jess.Context).

Parameters:

v - An argument to add to this Funcall

Returns:

This Funcall

See Also:

ValueVector.add(jess.Value)

arg

public Funcall arg(java.lang.String s)
            throws JessException

Calls ValueVector.add(jess.Value), then returns this object. This method does the same thing as add but returns this Funcall as a Funcall so the last call in a chain can be a call to execute(jess.Context).

Parameters:

s - An argument to add to this Funcall, interpreted as a symbol

Returns:

This Funcall

Throws:

JessException

See Also:

ValueVector.add(jess.Value)

arg

public Funcall arg(int i)
            throws JessException

Calls ValueVector.add(jess.Value), then returns this object. This method does the same thing as add but returns this Funcall as a Funcall so the last call in a chain can be a call to execute(jess.Context).

Parameters:

i - An argument to add to this Funcall, interpreted as an integer

Returns:

This Funcall

Throws:

JessException

See Also:

ValueVector.add(jess.Value)

arg

public Funcall arg(double f)
            throws JessException

Calls ValueVector.add(jess.Value), then returns this object. This method does the same thing as add but returns this Funcall as a Funcall so the last call in a chain can be a call to execute(jess.Context).

Parameters:

f - An argument to add to this Funcall, interpreted as an integer

Returns:

This Funcall

Throws:

JessException

See Also:

ValueVector.add(jess.Value)

arg

public Funcall arg(long l)
            throws JessException

Calls ValueVector.add(jess.Value), then returns this object. This method does the same thing as add but returns this Funcall as a Funcall so the last call in a chain can be a call to execute(jess.Context).

Parameters:

l - An argument to add to this Funcall, interpreted as a long

Returns:

This Funcall

Throws:

JessException

See Also:

ValueVector.add(jess.Value)

arg

public Funcall arg(Funcall f)
            throws JessException

Calls ValueVector.add(jess.Value), then returns this object. This method does the same thing as add but returns this Funcall as a Funcall so the last call in a chain can be a call to execute(jess.Context).

Parameters:

f - An argument to add to this Funcall, interpreted as a function call

Returns:

This Funcall

Throws:

JessException

See Also:

ValueVector.add(jess.Value)

arg

public Funcall arg(java.lang.Object o)
            throws JessException

Calls ValueVector.add(jess.Value), then returns this object. This method does the same thing as add but returns this Funcall as a Funcall so the last call in a chain can be a call to execute(jess.Context).

Parameters:

o - An argument to add to this Funcall, interpreted as a Java object

Returns:

This Funcall

Throws:

JessException

See Also:

ValueVector.add(jess.Value)

get

public Value get(int i)
          throws JessException

A version of ValueVector.get with more appropriate error messages. Fetch the entry at position i in this Funcall.

Overrides:

get in class ValueVector

Parameters:

i - The 0-based index of the Value to fetch

Returns:

The Value

Throws:

JessException

accept

public java.lang.Object accept(Visitor v)

Description copied from interface: Visitable

A proper accept() implementation should call one of the visitXXX() methods on the Visitor.

Specified by:

accept in interface Visitable

Parameters:

v - a visitor to invoke

Returns:

whatever the invoked Visitor method returns.