ubc.cs.JLog.Terms
Class jPredicate

java.lang.Object
  ubc.cs.JLog.Foundation.jType
      ubc.cs.JLog.Terms.jTerm
          ubc.cs.JLog.Terms.iPredicate
              ubc.cs.JLog.Terms.jPredicate

All Implemented Interfaces:

iType, iUnifiable, iConsultable, iName, iNameArity, iTerm, iValue

public class jPredicate
extends iPredicate

This is the base class for Prolog predicates.

Version:

%I%, %G%

Author:

Glendon Holst

Field Summary

protected jCompoundTerm	arguments
protected int	arity
protected jRuleDefinitions	cached_ruledefs
protected String	name

Fields inherited from class ubc.cs.JLog.Foundation.jType

type

Fields inherited from interface ubc.cs.JLog.Terms.iTerm

EQUAL, GREATER_THAN, LESS_THAN

Fields inherited from interface ubc.cs.JLog.Foundation.iType

TYPE_ARITHMETIC, TYPE_ATOM, TYPE_BUILTINPREDICATE, TYPE_COMMAND, TYPE_COMPARE, TYPE_COMPOUND, TYPE_CONS, TYPE_IF, TYPE_INTEGER, TYPE_LIST, TYPE_NULLLIST, TYPE_NUMERICCOMPARE, TYPE_OBJECT, TYPE_OPERATOR, TYPE_OR, TYPE_ORPREDICATE, TYPE_PREDICATE, TYPE_PREDICATETERMS, TYPE_REAL, TYPE_TYPE, TYPE_UNARYARITHMETIC, TYPE_UNARYOPERATOR, TYPE_UNDEFINED, TYPE_VARIABLE

Constructor Summary

	jPredicate(jAtom a) Copy constructor to convert jAtom to predicate/0
protected	jPredicate(String n) Constructor for subclasses which must set arguments and arity themselves.
	jPredicate(String n, jCompoundTerm args) jPredicate constructor.
protected	jPredicate(String n, jCompoundTerm args, int ar, jRuleDefinitions crds)

Method Summary

void	addGoals(jGoal g, iGoalStack goals) Adds goal to prove this predicate onto goal stack.
void	addGoals(jGoal g, jVariable[] vars, iGoalStack goals) Adds goal to prove this predicate onto goal stack.
void	addTerm(jTerm t)
protected int	compareArguments(iPredicate ipred, boolean first_call, boolean var_equal) Compares the arguments for predicates.
void	consult(jKnowledgeBase kb) Consult the given jKnowledgeBase and cache any invariant values (those which would not change until the next time the jKnowledgeBase changes).
void	consultReset() Called when the jKnowledgeBase changes.
jTerm	copy(jVariableRegistry vars) Internal member function which creates a copy of this term.
jTerm	duplicate(jVariable[] vars) Creates a complete and entirely independant duplicate of this term.
jCompoundTerm	duplicateArguments(jVariable[] vars)
void	enumerateVariables(jVariableVector v, boolean all) Adds variables belonging to this term (or belonging to any sub-part of this term) to the jVariableVector
boolean	equivalence(jTerm term, jEquivalenceMapping v) The public interface for evaluating term equivalence (i.e., structural similarity).
boolean	equivalenceArguments(jCompoundTerm term, jEquivalenceMapping v)
jCompoundTerm	getArguments() Accessor for the arguments for this predicate.
int	getArity() Returns the arity of this instance.
jRuleDefinitions	getCachedRuleDefinitions()
String	getName() Returns the name of this instance.
boolean	isConsultNeeded() Determine if cached values already exist and hence if consulting is required.
protected boolean	lookup_predicate()
void	registerUnboundVariables(jUnifiedVector v) Adds any unbound variables belonging to this term (or belonging to any sub-part of this term) to the jUnifiedVector
void	registerVariables(jVariableVector v) Adds all variables belonging to this term (or belonging to any sub-part of this term) to the jUnifiedVector Should be called during the consultation phase by rules for their owned terms both head and base.
void	removeTerm(jTerm t)
String	toString(boolean usename) Produces a string identifying this term, suitable for display to the console.
boolean	unify(jTerm term, jUnifiedVector v) Determines if this instance and term unify.
boolean	unifyArguments(jCompoundTerm term, jUnifiedVector v)

Methods inherited from class ubc.cs.JLog.Terms.iPredicate

compare

Methods inherited from class ubc.cs.JLog.Terms.jTerm

compare, copy, getTerm, getValue, requiresCompleteVariableState, toString

Methods inherited from class ubc.cs.JLog.Foundation.jType

getType, objectToString

Methods inherited from class java.lang.Object

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

Field Detail

name

protected String name

arity

protected int arity

arguments

protected jCompoundTerm arguments

cached_ruledefs

protected jRuleDefinitions cached_ruledefs

Constructor Detail

jPredicate

public jPredicate(String n,
                  jCompoundTerm args)

jPredicate constructor.

Parameters:

n - The predicates name.

args - The arguments for the predicate.

jPredicate

public jPredicate(jAtom a)

Copy constructor to convert jAtom to predicate/0

Parameters:

a - The jAtom.

jPredicate

protected jPredicate(String n)

Constructor for subclasses which must set arguments and arity themselves.

Parameters:

n - The predicates name.

jPredicate

protected jPredicate(String n,
                     jCompoundTerm args,
                     int ar,
                     jRuleDefinitions crds)

Method Detail

getName

public final String getName()

Description copied from interface: iName

Returns the name of this instance.

Specified by:

getName in interface iName

Specified by:

getName in interface iTerm

Overrides:

getName in class jTerm

Returns:

String containing name of this instance.

getArity

public final int getArity()

Description copied from interface: iNameArity

Returns the arity of this instance.

Returns:

int whose value is the arity of this instance.

compareArguments

protected int compareArguments(iPredicate ipred,
                               boolean first_call,
                               boolean var_equal)

Description copied from class: iPredicate

Compares the arguments for predicates. Like compare except that name and arity must be equal.

Specified by:

compareArguments in class iPredicate

Parameters:

ipred - the iPredicate to compare with this instance of iPredicate.

first_call - true if just invoked by public compare member function. false otherwise.

var_equal - if var_equal is true, then unbound variables are considered equal. var_equal = false is standard prolog behavior.

Returns:

LESS_THAN if this instance is less than term, EQUAL if the two terms are equal, and GREATER_THAN if this instance is greater than term.

getCachedRuleDefinitions

public jRuleDefinitions getCachedRuleDefinitions()

consult

public void consult(jKnowledgeBase kb)

Description copied from interface: iConsultable

Consult the given jKnowledgeBase and cache any invariant values (those which would not change until the next time the jKnowledgeBase changes). Where possible, consultable objects should minimize computation and assume that any cached values are still accurate.

Specified by:

consult in interface iConsultable

Specified by:

consult in interface iTerm

Overrides:

consult in class jTerm

Parameters:

kb - the knowledge base which attempted proofs are based upon.

consultReset

public void consultReset()

Description copied from interface: iConsultable

Called when the jKnowledgeBase changes. Should set all cached values to dirty so that a following call to consult would perform a full lookup as required.

Specified by:

consultReset in interface iConsultable

Specified by:

consultReset in interface iTerm

Overrides:

consultReset in class jTerm

isConsultNeeded

public boolean isConsultNeeded()

Description copied from interface: iConsultable

Determine if cached values already exist and hence if consulting is required. If object does not knowimmediatly whether consulting is needed, then assuming it is required.

Specified by:

isConsultNeeded in interface iConsultable

Specified by:

isConsultNeeded in interface iTerm

Overrides:

isConsultNeeded in class jTerm

Returns:

false if cached values are valid, true otherwise, if consult should be called.

addGoals

public void addGoals(jGoal g,
                     jVariable[] vars,
                     iGoalStack goals)

Description copied from class: iPredicate

Adds goal to prove this predicate onto goal stack. This version is called when the original predicate must duplicate itself (or its arguments). Add goals in the reverse order you want them evaluated.

Specified by:

addGoals in class iPredicate

Parameters:

g - The super-goal jGoal for the sub-goal that this function will add.

vars - The vector of duplicate variables produced from the previous call to registerVariables. Needed for call to duplicate.

goals - The iGoalStack to add the goal to.

addGoals

public void addGoals(jGoal g,
                     iGoalStack goals)

Description copied from class: iPredicate

Adds goal to prove this predicate onto goal stack. This version is called when the original predicate is already duplicated (usually as part of an argument for another predicate). Add goals in the reverse order you want them evaluated.

Specified by:

addGoals in class iPredicate

Parameters:

g - The super-goal jGoal for the sub-goal that this function will add.

goals - The iGoalStack to add the goal to.

registerUnboundVariables

public void registerUnboundVariables(jUnifiedVector v)

Description copied from class: jTerm

Adds any unbound variables belonging to this term (or belonging to any sub-part of this term) to the jUnifiedVector

Specified by:

registerUnboundVariables in interface iTerm

Overrides:

registerUnboundVariables in class jTerm

Parameters:

v - The jUnifiedVector where unbound variables are added to. This parameter is used to as output to the caller, not as input.

equivalence

public boolean equivalence(jTerm term,
                           jEquivalenceMapping v)

Description copied from interface: iTerm

The public interface for evaluating term equivalence (i.e., structural similarity).

Specified by:

equivalence in interface iTerm

Specified by:

equivalence in class jTerm

Parameters:

term - the jTerm to compare with this instance of jTerm.

v - v is the collection of equivalent variable pairs found. It should be empty when first calling this function.

Returns:

true if this instance is equivalent to term, false otherwise.

unify

public boolean unify(jTerm term,
                     jUnifiedVector v)

Description copied from interface: iUnifiable

Determines if this instance and term unify. Every variable which was previously unbound, but which becomes bound during the unification must register itself with the jUnifiedVector. It is the callers responsibility to deal with the unified vector.

Specified by:

unify in interface iUnifiable

Specified by:

unify in interface iTerm

Specified by:

unify in class jTerm

Parameters:

term - the term to unify with this instance.

v - the vector of variables bound during unification. Even if unification fails, this vector may contain recently bound vectors. This parameter is used to as output to the caller, not as input for unify.

Returns:

true if unification succeeded, false otherwise.

equivalenceArguments

public final boolean equivalenceArguments(jCompoundTerm term,
                                          jEquivalenceMapping v)

unifyArguments

public final boolean unifyArguments(jCompoundTerm term,
                                    jUnifiedVector v)

registerVariables

public void registerVariables(jVariableVector v)

Description copied from class: jTerm

Adds all variables belonging to this term (or belonging to any sub-part of this term) to the jUnifiedVector Should be called during the consultation phase by rules for their owned terms both head and base. all variables encountered should be unbound. After call, this term should not be modified in any way.

Specified by:

registerVariables in interface iTerm

Specified by:

registerVariables in class jTerm

Parameters:

v - The jUnifiedVector where variables are added to. This parameter is used to as output to the caller, not as input.

enumerateVariables

public void enumerateVariables(jVariableVector v,
                               boolean all)

Description copied from class: jTerm

Adds variables belonging to this term (or belonging to any sub-part of this term) to the jVariableVector

Specified by:

enumerateVariables in interface iTerm

Specified by:

enumerateVariables in class jTerm

Parameters:

v - The jVariabeVector where variables are added to. This parameter is used to as output to the caller, not as input.

all - If true, then all variables should register, otherwise only add non-existentially qualified variables.

duplicate

public jTerm duplicate(jVariable[] vars)

Description copied from class: jTerm

Creates a complete and entirely independant duplicate of this term. User should call only for terms for which registerVariables has already been invoked. Within duplicate, any other calls to duplicate should pass along the same vars array produced by registerVariables since the same duplication path previously taken by registerVariables should be taken by duplicate. This call is designed only for terms which belong to rules and are templates for instantiation. Any variables in the term should be unbound. As implied by the modification restrictions on registerVariables, terms and their children cannot change (especially during call!)

Specified by:

duplicate in interface iTerm

Specified by:

duplicate in class jTerm

Parameters:

vars - The user passes in a duplicate of the variable vector produced from the previous call to registerVariables. vars is produced from the jVariableVector by creating a single duplicate variable for each variable. Since this is created in the same order as the registerVariables, it is now efficient for jVariables to return their unique duplicate.

Returns:

jTerm which is an instantiated duplicate of this term.

copy

public jTerm copy(jVariableRegistry vars)

Description copied from class: jTerm

Internal member function which creates a copy of this term. This member function is designed to duplicate a term, but without the restrictions of the duplicate function. Should only be invoked by copy() or other copy(vars). Should only invoke other copy(vars) functions. Bound variables should return a copy of the bound term.

Specified by:

copy in interface iTerm

Specified by:

copy in class jTerm

Parameters:

vars - The registry of variables and their duplicates. Initially this is empty. As variables generate copies, they add themselves and their copy to the jVariableRegistry, and this is output from the function call. Any further calls with the same vars ensures that the same variable (in a different term) returns the same copy.

Returns:

jTerm which is an instantiated copy of this term.

getArguments

public final jCompoundTerm getArguments()

Description copied from class: iPredicate

Accessor for the arguments for this predicate. Don't modify arguments after consult. Arguments are not guaranteed to be original so modifying has an unspecified effect.

Overrides:

getArguments in class iPredicate

Returns:

The original or possibly duplicated arguments for this predicate.

addTerm

public void addTerm(jTerm t)

removeTerm

public void removeTerm(jTerm t)

duplicateArguments

public jCompoundTerm duplicateArguments(jVariable[] vars)

toString

public String toString(boolean usename)

Description copied from class: jTerm

Produces a string identifying this term, suitable for display to the console. param usename determines whether to display variables by name or identity. false is the default for displaying the term, true for displaying this term in a user query.

Specified by:

toString in interface iTerm

Specified by:

toString in class jTerm

Returns:

String which is a textual representation of this term.

lookup_predicate

protected boolean lookup_predicate()