jess
Class Value

java.lang.Object
  jess.Value

All Implemented Interfaces:

java.io.Serializable

Direct Known Subclasses:

BindingValue, FactIDValue, FuncallValue, LongValue, Variable

public class Value

extends java.lang.Object

implements java.io.Serializable

A class to represent a Jess typed value. Does some 'type conversions'. Subclasses of this are used to represent Variables and other special types.

(C) 1998 E.J. Friedman-Hill and the Sandia Corporation

Author:

Ernest J. Friedman-Hill

See Also:

Serialized Form

Constructor Summary

Value(boolean b)
Contruct a boolean value object (one of the RU.ATOMs TRUE or FALSE.

Value(double d, int type)
Contruct a value of floating-point type.

Value(int value, int type)
Contruct a value of integral type.

Value(java.lang.Object o)
Contruct a value of external address type.

Value(java.lang.String s, int type)
Contruct a value of String type.

Value(Value v)
Contruct a value that is a copy of another Value.

Value(ValueVector f, int type)
Contruct a value of list type.

Method Summary

java.lang.String	atomValue(Context c) Returns the contents of this value, as an atom
boolean	equals(java.lang.Object v) Compare this value to another object.
boolean	equals(Value v) Compare this value to another value.
boolean	equalsStar(Value v) Like equals(Value) above, but returns true for 3 == 3.0
java.lang.Object	externalAddressValue(Context c) Returns the contents of this value, as an external adress object
Fact	factValue(Context c) Returns the contents of this value, as a fact
double	floatValue(Context c) Returns the contents of this value, as a number
Funcall	funcallValue(Context c) Returns the contents of this value, as a function call.
int	hashCode() Return a hashcode for the object
int	intValue(Context c) Returns the contents of this value, as an int
ValueVector	listValue(Context c) Returns the contents of this value, as a list
long	longValue(Context c) Returns the contents of this value, as a long
double	numericValue(Context c) Returns the contents of this value, as a number
Value	resolveValue(Context c) Given an evaluation context, return the "true value" of this Value.
java.lang.String	stringValue(Context c) Returns the contents of this value, as a String
java.lang.String	toString() Pretty-print this value, without adding parens to any lists
java.lang.String	toStringWithParens() Pretty-print this value, adding parens to any lists
int	type() Return the type of this variable.
java.lang.String	variableValue(Context c) Returns the contents of this value, as a String (a variable name)

Methods inherited from class java.lang.Object

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

Constructor Detail

Value

public Value(int value,
             int type)
      throws JessException

Contruct a value of integral type. Allowed type values are NONE and INTEGER

Parameters:

value - The value

type - The type

Throws:

JessException - If the value and type don't match.

Value

public Value(Value v)

Contruct a value that is a copy of another Value.

Parameters:

v - Value to copy

Value

public Value(java.lang.String s,
             int type)
      throws JessException

Contruct a value of String type. Allowed type values are RU.ATOM, RU.STRING, RU.SLOT and RU.MULTISLOT.

Parameters:

s - The value

type - The type

Throws:

JessException - If the value and type don't match.

Value

public Value(ValueVector f,
             int type)
      throws JessException

Contruct a value of list type. Allowed type values are FACT and LIST.

Parameters:

f - The value

type - The type

Throws:

JessException - If the value and type don't match.

Value

public Value(double d,
             int type)
      throws JessException

Contruct a value of floating-point type. Allowed type values are FLOAT, LONG, and INTEGER -- although LONG can only be used if this is called from the subclass LongValue.

Parameters:

d - The value

type - The type

Throws:

JessException - If the value and type don't match.

Value

public Value(boolean b)

Contruct a boolean value object (one of the RU.ATOMs TRUE or FALSE.

Parameters:

b - The value

Value

public Value(java.lang.Object o)

Contruct a value of external address type.

Parameters:

o - The value

Method Detail

externalAddressValue

public java.lang.Object externalAddressValue(Context c)
                                      throws JessException

Returns the contents of this value, as an external adress object

Returns:

The external address object

Throws:

JessException - If this value does not contain an object

funcallValue

public Funcall funcallValue(Context c)
                     throws JessException

Returns the contents of this value, as a function call.

Returns:

The function call object

Throws:

JessException - If this value does not contain a function call

factValue

public Fact factValue(Context c)
               throws JessException

Returns the contents of this value, as a fact

Returns:

The fact

Throws:

JessException - If this value does not contain a fact

listValue

public ValueVector listValue(Context c)
                      throws JessException

Returns the contents of this value, as a list

Returns:

The list

Throws:

JessException - If this value does not contain a list

numericValue

public double numericValue(Context c)
                    throws JessException

Returns the contents of this value, as a number

Returns:

The number as a double

Throws:

JessException - If this value does not contain any kind of number

intValue

public int intValue(Context c)
             throws JessException

Returns the contents of this value, as an int

Returns:

The number as an int

Throws:

JessException - If this value does not contain any kind of number

longValue

public long longValue(Context c)
               throws JessException

Returns the contents of this value, as a long

Returns:

The number as a long

Throws:

JessException - If this value does not contain any kind of number

floatValue

public double floatValue(Context c)
                  throws JessException

Returns the contents of this value, as a number

Returns:

The number as a double

Throws:

JessException - If this value does not contain any kind of number

atomValue

public java.lang.String atomValue(Context c)
                           throws JessException

Returns the contents of this value, as an atom

Returns:

The atom

Throws:

JessException - If this value does not contain any kind of String

variableValue

public java.lang.String variableValue(Context c)
                               throws JessException

Returns the contents of this value, as a String (a variable name)

Returns:

The name of the variable

Throws:

JessException - If this value does not contain a variable

stringValue

public java.lang.String stringValue(Context c)
                             throws JessException

Returns the contents of this value, as a String

Returns:

The string

Throws:

JessException - If this value does not contain any kind of String

toString

public java.lang.String toString()

Pretty-print this value, without adding parens to any lists

Returns:

The formatted string

toStringWithParens

public java.lang.String toStringWithParens()

Pretty-print this value, adding parens to any lists

Returns:

The formatted string

type

public int type()

Return the type of this variable. Always one of the constants in jess.RU.

Returns:

The type

equals

public boolean equals(java.lang.Object v)

Compare this value to another object. As a convenience, if the parameter is not a Value, it will be compared to any contained Object inside this Vector (a String or external address object.)

Parameters:

v - The object to compare to.

Returns:

True if the objects are equivalent.

equals

public boolean equals(Value v)

Compare this value to another value. Believe it or not, using this separate overloaded routine has a measurable impact on performance - since so much time is spent comparing Values.

Parameters:

v - The Value to compare to.

Returns:

True if the Values are equivalent.

equalsStar

public boolean equalsStar(Value v)

Like equals(Value) above, but returns true for 3 == 3.0

Parameters:

v - Value to compare to

Returns:

True if the values are loosely equivalent

hashCode

public int hashCode()

Return a hashcode for the object

Returns:

The hashcode

resolveValue

public Value resolveValue(Context c)
                   throws JessException

Given an evaluation context, return the "true value" of this Value. For this class, the true value is always "this". For subclasses, the Context may be used to compute a new Value.

Parameters:

c - An execution context. You can pass null if you are sure that you're not calling this method on a subclass that uses the argument.

Returns:

This object

Throws:

JessException

See Also:

Variable, Funcall