com.ibm.able.data
Class AblePredicate

java.lang.Object
  com.ibm.able.data.AblePredicate

All Implemented Interfaces:

java.io.Serializable

Direct Known Subclasses:

AbleEmptyListPredicate

public class AblePredicate

extends java.lang.Object

implements java.io.Serializable

This class represents a single predicate-logic predicate with a name, and zero or more arguments which could be Strings, Literals, Variables or other predicates. AblePredicates are processed by the AblePredicateEngine and are used in AblePredicateRules and AblePredicateFacts.

See Also:

Serialized Form

Field Summary

protected java.util.Vector	argList The list of arguments which could be Strings, Literals, Variables, or Predicates
protected int	arity
static java.lang.String	AssertAPredicate The name of a special predicate denoting a "asserta" predicate.
static java.lang.String	AssertPredicate The name of a special predicate denoting a "assert" predicate.
static java.lang.String	AssertZPredicate The name of a special predicate denoting a "assertz" predicate.
static java.lang.String	AtomCharsPredicate The name of a special predicate denoting a "atom_charts" predicate.
static java.lang.String	AtomConcatPredicate The name of a special predicate denoting a "atom_concat" predicate.
static java.lang.String	AtomLengthPredicate The name of a special predicate denoting a "atom_length" predicate.
static java.lang.String	AtomNumberPredicate The name of a special predicate denoting a "atom_number" predicate.
static java.lang.String	CallPredicate The name of a special predicate denoting a "call" predicate.
static java.lang.String	ConsultPredicate The name of a special predicate denoting a "consult" predicate.
static java.lang.String	CutPredicate The name of a special predicate denoting a "cut" predicate.
static java.lang.String	DontCareSymbol The "don't care" symbol for use in predicate clauses.
static AbleEmptyListPredicate	EmptyListPredicate A special predicate that is the empty "list" predicate: .().
static java.lang.String	FailPredicate The name of a special predicate denoting a "fail" predicate.
static java.lang.String	FunctorPredicate The name of a special predicate denoting a "functor" predicate.
static java.lang.String	IsListPredicate The name of a special predicate denoting a "isList" predicate.
static java.lang.String	ListPredicate The name of a special predicate denoting a "list" predicate.
static java.lang.String	MemberPredicate The name of a special predicate denoting a "member" predicate.
protected AbleLogger	myTracer
protected java.lang.String	name
static java.lang.String	NonVarPredicate The name of a special predicate denoting a "nonvar" predicate.
static java.lang.String	NotPredicate The name of a special predicate denoting a "not" predicate.
protected java.util.Hashtable	replacementVars This hashtable is used when duplicating a predicate fact or rule during inferencing.
static java.lang.String	RetractAllPredicate The name of a special predicate denoting a "retractall" predicate.
static java.lang.String	RetractPredicate The name of a special predicate denoting a "retract" predicate.
static java.lang.String	SubAtomPredicate The name of a special predicate denoting a "sub_atom" predicate.
static java.lang.String	UnifyPredicate The name of a special predicate denoting a "unify" predicate.
static java.lang.String	UnivPredicate The name of a special predicate denoting a "univ" predicate.
protected java.util.Vector	variables variables is a list of all of the AbleVariable objects that appear in this predicate (and embedded arguments).
static java.lang.String	VarPredicate The name of a special predicate denoting a "var" predicate.

Constructor Summary

AblePredicate()

AblePredicate(AblePredicate thePredicate)
Construct a copy of the predicate with all local variables duplicated with same name and value.

AblePredicate(java.lang.Object head, AblePredicate tail)
Construct a standard list predicate with a head and a predicate list as the tail

AblePredicate(java.lang.String name)
Create an AblePredicate object with specified name

AblePredicate(java.lang.String name, java.util.Vector argList)
Create an AblePredicate object with name and arguments.

AblePredicate(java.util.Vector argList)
Create an AblePredicate list object with name "." and arguments.

Method Summary

java.lang.String	arlString() Return a formal rule language string that describes this clause.
java.lang.String	armlString() Return a formal XML string that describes this clause.
void	clearBindings() Sets all variables in this predicate to null values
void	clearBindings(java.util.Vector unboundVars) Sets selected variables to null
AblePredicate	createMatchPredicate(java.util.Hashtable replacementVars) Create a copy of this predicate with unbound copies of any variables This copy is used in the match() method in AblePredicateEngine
boolean	equals(java.lang.Object otherObj)
protected void	findAllVariables() Find all contained variables and initialize the variables member
java.lang.Object	getArgument(int index) Get an argument from the predicate at specified index
java.util.Vector	getArguments() Get the list of arguments in this predicate
int	getArity() Get the predicate arity (number of arguments)
java.util.Vector	getBoundVariables() Returns all bound variables in this and any contained predicates Note: this list should not contain duplicates
java.lang.String	getFunctor() Get the predicate name or functor
java.lang.Object	getHead() Get the head (first argument) of a predicate list Note: Caller should use isList() before this method is called
java.util.Vector	getListArguments() Return a list predicate as a Vector; that is, unwind the list.
java.lang.String	getSignature() Get a unique signature based on predicate name and arity
protected static AblePredicate	getStandardList(java.util.Vector atomList) Take this Vector of args and turn it into the standard Prolog/Lisp list structure with a head and tail for each element in the list.
java.lang.Object	getTail() Get the tail (second arg) of a predicate list Note: Caller should use isList() before this method is called
java.lang.String	getTemplateString(java.util.Vector theTemplateVars) Retrieve a text format string for use by rule templates.
java.util.Vector	getUnboundVariables() Get a list of all unbound variables in this predicate (and any contained predicates) Note: this list will not contain any duplicates
java.util.Vector	getVariables() Return all variables contained in this predicate
int	hashCode()
boolean	isBound() Returns true if all variables are bound (non-null)
boolean	isCut() Test if the predicate name is "cut" with 0-arity (no args)
boolean	isEmptyList() Test is this predicate is an empty list
boolean	isFail() Test if the predicate name is "fail" with 0 arity (no args)
boolean	isGround() Test if this predicate is ground (contains no variables)
boolean	isList() Test if this predicate represents a List
boolean	isMember(java.lang.Object fact)
boolean	isNot() Test if this predicate represents a not(X) predicate
static java.lang.String	listToString(AblePredicate predList) Take a list predicate and turn it into a [ ] format string
AblePredicate	makeGround() Construct a ground instance (contains no variables) of this predicate All bound variables are removed and replaced by literals.
java.lang.String	toString() Return a String representation of this predicate
java.lang.String	traceString(int theTraceStringFlavor) Retrieve a string describing (the contents of) the object.
java.lang.String	xmlCRdString() Return a formal XML "clause read" string that describes this data object.
java.lang.String	xmlString() Return a formal XML string that describes this clause.

Methods inherited from class java.lang.Object

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

Field Detail

name

protected java.lang.String name

arity

protected int arity

argList

protected java.util.Vector argList

The list of arguments which could be Strings, Literals, Variables, or Predicates

replacementVars

protected java.util.Hashtable replacementVars

This hashtable is used when duplicating a predicate fact or rule during inferencing. The original variables are used as the keys, and duplicate variables are constructed and placed in the hashtable values. This is used by createMatchPredicate()

variables

protected java.util.Vector variables

variables is a list of all of the AbleVariable objects that appear in this predicate (and embedded arguments).

myTracer

protected AbleLogger myTracer

DontCareSymbol

public static final java.lang.String DontCareSymbol

The "don't care" symbol for use in predicate clauses.

See Also:

Constant Field Values

ListPredicate

public static final java.lang.String ListPredicate

The name of a special predicate denoting a "list" predicate.

See Also:

Constant Field Values

IsListPredicate

public static final java.lang.String IsListPredicate

The name of a special predicate denoting a "isList" predicate.

See Also:

Constant Field Values

EmptyListPredicate

public static final AbleEmptyListPredicate EmptyListPredicate

A special predicate that is the empty "list" predicate: .().

NotPredicate

public static final java.lang.String NotPredicate

The name of a special predicate denoting a "not" predicate.

See Also:

Constant Field Values

CutPredicate

public static final java.lang.String CutPredicate

The name of a special predicate denoting a "cut" predicate.

See Also:

Constant Field Values

FailPredicate

public static final java.lang.String FailPredicate

The name of a special predicate denoting a "fail" predicate.

See Also:

Constant Field Values

CallPredicate

public static final java.lang.String CallPredicate

The name of a special predicate denoting a "call" predicate.

See Also:

Constant Field Values

UnivPredicate

public static final java.lang.String UnivPredicate

The name of a special predicate denoting a "univ" predicate.

See Also:

Constant Field Values

AtomCharsPredicate

public static final java.lang.String AtomCharsPredicate

The name of a special predicate denoting a "atom_charts" predicate.

See Also:

Constant Field Values

AtomConcatPredicate

public static final java.lang.String AtomConcatPredicate

The name of a special predicate denoting a "atom_concat" predicate.

See Also:

Constant Field Values

SubAtomPredicate

public static final java.lang.String SubAtomPredicate

The name of a special predicate denoting a "sub_atom" predicate.

See Also:

Constant Field Values

VarPredicate

public static final java.lang.String VarPredicate

The name of a special predicate denoting a "var" predicate.

See Also:

Constant Field Values

NonVarPredicate

public static final java.lang.String NonVarPredicate

The name of a special predicate denoting a "nonvar" predicate.

See Also:

Constant Field Values

AssertPredicate

public static final java.lang.String AssertPredicate

The name of a special predicate denoting a "assert" predicate.

See Also:

Constant Field Values

AssertAPredicate

public static final java.lang.String AssertAPredicate

The name of a special predicate denoting a "asserta" predicate.

See Also:

Constant Field Values

AssertZPredicate

public static final java.lang.String AssertZPredicate

The name of a special predicate denoting a "assertz" predicate.

See Also:

Constant Field Values

RetractPredicate

public static final java.lang.String RetractPredicate

The name of a special predicate denoting a "retract" predicate.

See Also:

Constant Field Values

RetractAllPredicate

public static final java.lang.String RetractAllPredicate

The name of a special predicate denoting a "retractall" predicate.

See Also:

Constant Field Values

MemberPredicate

public static final java.lang.String MemberPredicate

The name of a special predicate denoting a "member" predicate.

See Also:

Constant Field Values

UnifyPredicate

public static final java.lang.String UnifyPredicate

The name of a special predicate denoting a "unify" predicate.

See Also:

Constant Field Values

ConsultPredicate

public static final java.lang.String ConsultPredicate

The name of a special predicate denoting a "consult" predicate.

See Also:

Constant Field Values

AtomNumberPredicate

public static final java.lang.String AtomNumberPredicate

The name of a special predicate denoting a "atom_number" predicate.

See Also:

Constant Field Values

FunctorPredicate

public static final java.lang.String FunctorPredicate

The name of a special predicate denoting a "functor" predicate.

See Also:

Constant Field Values

AtomLengthPredicate

public static final java.lang.String AtomLengthPredicate

The name of a special predicate denoting a "atom_length" predicate.

See Also:

Constant Field Values

Constructor Detail

AblePredicate

public AblePredicate()

AblePredicate

public AblePredicate(java.lang.String name)

Create an AblePredicate object with specified name

AblePredicate

public AblePredicate(java.lang.String name,
                     java.util.Vector argList)

Create an AblePredicate object with name and arguments. If this is a predicate list (name = ".") then the argList must end with an empty predicate list (AblePredicate.EmptyListPredicate) or a local variable.

Parameters:

name - A String containing the predicate name

argList - A Vector containing the predicate arguments. These could be other predicates, antecedent or consequent clauses, Symbols (strings) BooleanLiteral, StringLiteral or DoubleLiteral, CharacterLiteral or IntegerLiteral objects. There must be at least two arguments provided. If more than two arguments are provided, the atomic head and tail predicates are included automatically.

AblePredicate

public AblePredicate(java.util.Vector argList)

Create an AblePredicate list object with name "." and arguments. If the argList is empty, an EmptyListPredicate ([]) will be returned. If the argList is non-empty an EmptyListPredicate will be added to the end of the argList and an AblePredicate list will be returned.

Parameters:

argList - A Vector containing the predicate list arguments.

AblePredicate

public AblePredicate(java.lang.Object head,
                     AblePredicate tail)

Construct a standard list predicate with a head and a predicate list as the tail

Parameters:

head - An Object representing the head of the list

tail - A List predicate representing the tail of the list

AblePredicate

public AblePredicate(AblePredicate thePredicate)

Construct a copy of the predicate with all local variables duplicated with same name and value.

Parameters:

thePredicate - The predicate object to be copied

Method Detail

isMember

public boolean isMember(java.lang.Object fact)
                 throws AbleDataException

Throws:

AbleDataException

equals

public boolean equals(java.lang.Object otherObj)

hashCode

public int hashCode()

getSignature

public java.lang.String getSignature()

Get a unique signature based on predicate name and arity

Returns:

the signature string

getFunctor

public java.lang.String getFunctor()

Get the predicate name or functor

Returns:

the signature string

getArity

public int getArity()

Get the predicate arity (number of arguments)

Returns:

the arity

isList

public boolean isList()

Test if this predicate represents a List

Returns:

true if the predicate name is "." which means it is a list

isEmptyList

public boolean isEmptyList()

Test is this predicate is an empty list

Returns:

true if the predicate name is "." which means it is a list and it has zero arguments which means it is empty

isNot

public boolean isNot()

Test if this predicate represents a not(X) predicate

Returns:

true if the predicate name is "not"

getArgument

public java.lang.Object getArgument(int index)

Get an argument from the predicate at specified index

Parameters:

index - The argument (0-based) to retrieve.

Returns:

the argument Object.

getArguments

public java.util.Vector getArguments()

Get the list of arguments in this predicate

Returns:

the Vector of argument objects.

getVariables

public java.util.Vector getVariables()

Return all variables contained in this predicate

Returns:

the Vector of variables.

isGround

public boolean isGround()

Test if this predicate is ground (contains no variables)

Returns:

true if this predicate is ground, false otherwise

isFail

public boolean isFail()

Test if the predicate name is "fail" with 0 arity (no args)

Returns:

true if the predicate is the "fail" predicate

isCut

public boolean isCut()

Test if the predicate name is "cut" with 0-arity (no args)

Returns:

true if the predicate is the "cut" predicate

getHead

public java.lang.Object getHead()

Get the head (first argument) of a predicate list Note: Caller should use isList() before this method is called

Returns:

the head (first arg) of the list

getTail

public java.lang.Object getTail()

Get the tail (second arg) of a predicate list Note: Caller should use isList() before this method is called

Returns:

the tail (second arg) of the list

makeGround

public AblePredicate makeGround()

Construct a ground instance (contains no variables) of this predicate All bound variables are removed and replaced by literals.

Returns:

a ground instance of this predicate

isBound

public boolean isBound()

Returns true if all variables are bound (non-null)

getStandardList

protected static AblePredicate getStandardList(java.util.Vector atomList)

Take this Vector of args and turn it into the standard Prolog/Lisp list structure with a head and tail for each element in the list. This method is used by the AblePredicate constructor called by the Parser to convert a Vector of list args into an embedded structure of Predicate lists. so [ 1,2,3,4] looks like .( 1, .( 2, .(3, .(4, []) ) ) ) and [1,2,3 | A] looks like .(1, .(2, .(3, A) ) )

Parameters:

atomList - A vector of list elements (objects)

createMatchPredicate

public AblePredicate createMatchPredicate(java.util.Hashtable replacementVars)

Create a copy of this predicate with unbound copies of any variables This copy is used in the match() method in AblePredicateEngine

Parameters:

replacementVars - A set of unbound variable instances to be used as replacements when a copy of this predicate is constructed.

getUnboundVariables

public java.util.Vector getUnboundVariables()
                                     throws AbleDataException

Get a list of all unbound variables in this predicate (and any contained predicates) Note: this list will not contain any duplicates

Returns:

a Vector of unbound variables

Throws:

AbleDataException

findAllVariables

protected void findAllVariables()

Find all contained variables and initialize the variables member

getBoundVariables

public java.util.Vector getBoundVariables()

Returns all bound variables in this and any contained predicates Note: this list should not contain duplicates

clearBindings

public void clearBindings()

Sets all variables in this predicate to null values

clearBindings

public void clearBindings(java.util.Vector unboundVars)

Sets selected variables to null

Parameters:

unboundVars - A Vector of unbound variables that should be reset to AbleData.StringNull

getListArguments

public java.util.Vector getListArguments()

Return a list predicate as a Vector; that is, unwind the list. Note: isList() should be called on this predicate before calling this method

Returns:

A Vector containing the list elements

listToString

public static java.lang.String listToString(AblePredicate predList)

Take a list predicate and turn it into a [ ] format string

Parameters:

predList - A predicate list object

Returns:

A formatted string representation of the list with brackets [ ]

arlString

public java.lang.String arlString()

Return a formal rule language string that describes this clause.

Returns:

A String that describes this clause in formal rule language.

getTemplateString

public java.lang.String getTemplateString(java.util.Vector theTemplateVars)

Retrieve a text format string for use by rule templates. The string contains "{n}" strings, where the index 'n' corresponds to the template variables defined in the rule template. This string is based on the standard arlString() representation of the rule. After replacement of the template variable values, the resulting string must be a valid ARL format string that can be parsed.

Parameters:

theTemplateVars - An ordered list of template variables referenced by this rule.

Returns:

A Text format string used to create a new rule instance.

armlString

public java.lang.String armlString()

Return a formal XML string that describes this clause.

Returns:

A String that describes this clause in XML.

xmlCRdString

public java.lang.String xmlCRdString()

Return a formal XML "clause read" string that describes this data object.

Returns:

A String describing the data object in XML.

xmlString

public java.lang.String xmlString()

Return a formal XML string that describes this clause.

Returns:

A String that describes this clause in XML.

toString

public java.lang.String toString()

Return a String representation of this predicate

traceString

public java.lang.String traceString(int theTraceStringFlavor)

Retrieve a string describing (the contents of) the object.

Parameters:

theTraceStringFlavor - An Able.TraceStringFlavor value.

Returns:

A String containing the current contents of the object.