gnu.prolog.database
Class Predicate

java.lang.Object
  gnu.prolog.database.Predicate

public class Predicate
extends Object

Predicate in database

Author:

Contantine A Plotnikov

Nested Class Summary

static class

Predicate.TYPE The possible types of Predicate

Field Summary

protected List<Term>	clauses list of clauses for this predicate
protected boolean	dynamicFlag dynamic property of predicate
protected Set<String>	files set files where this predicate is defined
protected String	javaClassName class name for external predicate
protected Module	module current module
protected boolean	propertiesLocked flag which indicate that clauses was added for this predicate
protected CompoundTermTag	tag a tag of predicate head
protected Predicate.TYPE	type type of predicate.

Constructor Summary

Predicate(Module module, CompoundTermTag tag)
constructor of predicate

Method Summary

void	addClauseFirst(Term clause) Add clause for predicate at the beginning.
void	addClauseLast(Term clause) Add clause for predicate at the end.
boolean	arePropertiesLocked() Check if properties of predicate could be changed at this moment
int	getArity() get arity of predicate
List<Term>	getClauses() get clauses of predicate You must synchronize on this class when iterating through this list as although it is a synchronized list you are getting a unmodifiable view of that list.
AtomTerm	getFunctor() get functor of predicate
String	getJavaClassName() Get name of Java class that defines this predicate.
CompoundTermTag	getTag() get tag of predicate
Predicate.TYPE	getType() get type of predicate
boolean	isDynamic() Check if predicate is dynamic.
static Term	prepareBody(Term body)
static Term	prepareClause(Term clause)
static Term	prepareHead(Term head)
void	removeClause(Term clause) Remove clause for predicate.
void	setDynamic() set "dynamic" property of predicate to true.
void	setJavaClassName(String javaClassName) set java class name of the predicate.
void	setType(Predicate.TYPE type) set type of predicate

Methods inherited from class java.lang.Object

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

Field Detail

type

protected Predicate.TYPE type

type of predicate. It should be either UNDEFINED, CONTROL ,BUILD_IN, USER_DEFINED or EXTERNAL

tag

protected CompoundTermTag tag

a tag of predicate head

clauses

protected List<Term> clauses

list of clauses for this predicate

propertiesLocked

protected boolean propertiesLocked

flag which indicate that clauses was added for this predicate

dynamicFlag

protected boolean dynamicFlag

dynamic property of predicate

javaClassName

protected String javaClassName

class name for external predicate

files

protected Set<String> files

set files where this predicate is defined

module

protected Module module

current module

Constructor Detail

Predicate

public Predicate(Module module,
                 CompoundTermTag tag)

constructor of predicate

Parameters:

module -

tag -

Method Detail

getClauses

public List<Term> getClauses()

get clauses of predicate You must synchronize on this class when iterating through this list as although it is a synchronized list you are getting a unmodifiable view of that list.

Returns:

an unmodifiable list of the clauses of the Predicate

getType

public Predicate.TYPE getType()

get type of predicate

Returns:

type of predicate

setType

public void setType(Predicate.TYPE type)

set type of predicate

Parameters:

type - type of predicate

Throws:

IllegalStateException - if predicate type is already set

getJavaClassName

public String getJavaClassName()

Get name of Java class that defines this predicate.

Returns:

true if predicate is external, false otherwise.

setJavaClassName

public void setJavaClassName(String javaClassName)

set java class name of the predicate.

Parameters:

javaClassName - the class name to set

getFunctor

public AtomTerm getFunctor()

get functor of predicate

Returns:

the functor for the predicate. e.g. in foo(X,Y) the functor is 'foo'

getArity

public int getArity()

get arity of predicate

Returns:

the arity of the Predicate

getTag

public CompoundTermTag getTag()

get tag of predicate

Returns:

the tag of the predicate

addClauseLast

public void addClauseLast(Term clause)

Add clause for predicate at the end. This method simply add clause to predicate. No modification to term is done. It even is not copied.

Parameters:

clause - a clause to add

addClauseFirst

public void addClauseFirst(Term clause)

Add clause for predicate at the beginning. This method simply add clause to predicate. No modification to term is done. It even is not copied.

Parameters:

clause - a clause to add

removeClause

public void removeClause(Term clause)

Remove clause for predicate. This method remove first clause which is identical to clause.

Parameters:

clause - a clause to remove

arePropertiesLocked

public boolean arePropertiesLocked()

Check if properties of predicate could be changed at this moment

Returns:

true if properties of predicate could be changed at this moment

isDynamic

public boolean isDynamic()

Check if predicate is dynamic.

Returns:

true if predicate is dynamic, false otherwise.

setDynamic

public void setDynamic()

set "dynamic" property of predicate to true. This method should be called first time before any clause was added.

Throws:

IllegalStateException - if there were clauses added to predicate and dynamic flag was not set before. See 7.4.2.1 clause of ISO Prolog.

prepareClause

public static Term prepareClause(Term clause)

prepareHead

public static Term prepareHead(Term head)

prepareBody

public static Term prepareBody(Term body)