se.sics.prologbeans

Class QueryAnswer

java.lang.Object

se.sics.prologbeans.Bindings

se.sics.prologbeans.QueryAnswer

public class QueryAnswer
extends Bindings

The representation of an answer from the Prolog server.

The QueryAnswer is returned by PrologSession in response to a query and contains variable bindings, errors, and success/failure information. It also contains the variable bindings specified in the query.

Note that this implementation is not synchronized.

Constructor Summary

Constructors

Constructor and Description
QueryAnswer(PBTerm answer, Bindings bindings) Creates a new QueryAnswer instance with the specified information.

Method Summary

Modifier and Type	Method and Description
java.lang.String	getError() Returns the error reason or null if an error has not occurred or if no error reason is known.
PBTerm	getValue(java.lang.String variable) Returns the value of the specified variable or null if the variable is not bound.
boolean	isError() Returns true if an error occurred while processing the query and false otherwise.
boolean	queryFailed() Returns true if the query failed (i.e. the Prolog responded with 'no') and false otherwise.
java.lang.String	toString() Returns a string description of this answer.

Methods inherited from class se.sics.prologbeans.Bindings

bind, bind, bind, bind, bind, bind, bindAtom

Methods inherited from class java.lang.Object

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

Constructor Detail

QueryAnswer

public QueryAnswer(PBTerm answer,
                   Bindings bindings)

Creates a new QueryAnswer instance with the specified information.

Parameters:

answer - a PBTerm value representing the Prolog response

bindings - the variable bindings for the query to which this is an answer

Method Detail

getValue

public PBTerm getValue(java.lang.String variable)

Returns the value of the specified variable or null if the variable is not bound.

Overrides:

getValue in class Bindings

Parameters:

variable - the name of the variable

Returns:

the value of the variable as a PBTerm or null if the variable is not bound

queryFailed

public boolean queryFailed()

Returns true if the query failed (i.e. the Prolog responded with 'no') and false otherwise.

Returns:

whether the query failed

isError

public boolean isError()

Returns true if an error occurred while processing the query and false otherwise.

Returns:

whether the query threw an exception

getError

public java.lang.String getError()

Returns the error reason or null if an error has not occurred or if no error reason is known.

Returns:

the error, or null, if none

toString

public java.lang.String toString()

Returns a string description of this answer.

Overrides:

toString in class Bindings