se.sics.jasper

Class SPQuery

java.lang.Object

se.sics.jasper.SPQuery

All Implemented Interfaces:

Query

public class SPQuery
extends java.lang.Object
implements Query

This class is used for holding a query-reference which is used to find multiple solutions to a query. This class is never instantiated explicitly by the user.

You should not inherit from SPQuery.

See Also:

SICStus.openQuery(java.lang.String, java.lang.String, se.sics.jasper.SPTerm[])

Method Summary

Modifier and Type	Method and Description
void	close() Closes a query.
void	cut() Discards choices made since this query object was created, like the goal !
boolean	nextSolution() Gets the next solution for the query.

Methods inherited from class java.lang.Object

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

Method Detail

nextSolution

public boolean nextSolution()
                     throws SPException

Gets the next solution for the query. Returns false when there are no more solutions. When no more solutions are needed, the query must be closed using the method close().

Multiple queries can be open at the same time, but the calls to nextSolution must be nested, i.e. refer to the most recently opened query. Invalidates all SPTerm objects created since this query was created

Invalidates all SPTerm objects created since this query was created If you need to keep data created by the previous call to nextSolution to this query (i.e. data referred to by SPTerm objects), you need to convert it to Java data types before calling this function.

Specified by:

nextSolution in interface Query

Returns:

False if there are no more solutions, True otherwise.

Throws:

SPException - If a Prolog exception was thrown during the query.

See Also:

SICStus.openQuery(java.lang.String, java.lang.String, se.sics.jasper.SPTerm[]), close(), cut()

close

public void close()

Closes a query. All remaining solutions to the query are discarded, and the state of the Prolog engine will be restored to the state it was in when openQuery was called. If the query is not the most recently opened, all still open queries opened after this query will be closed as well.

A closed or cut query is invalidated and most operations on it will throw an exception. In particular you should not call close, cut or nextSolution on an invalidated query.

Invalidates all SPTerm objects created since this query was created If you need to keep data created by the query (i.e. data referred to by SPTerm objects), you need to convert it to Java datatypes before calling this function.

Specified by:

close in interface Query

cut

public void cut()
         throws SPException

Discards choices made since this query object was created, like the goal !.

If the query is not the most recently opened, all still open queries opened after this query will be cut as well.

A closed or cut query is invalidated and most operations on it will throw an exception. In particular you should not call close, cut or nextSolution on an invalidated query.

Invalidates all SPTerm objects created since this query was created If you need to keep data created by the query (i.e. data referred to by SPTerm objects), you need to convert it to Java datatypes before calling this function.

Specified by:

cut in interface Query

Throws:

SPException