Helfer OutInLimit

Jan Burse, erstellt 15. Sep 2018
package example05;
import jekpro.platform.headless.ToolkitLibrary;
import jekpro.tools.call.*;
import jekpro.tools.term.AbstractTerm;
import jekpro.tools.term.Knowledgebase;
import jekpro.tools.term.TermCompound;
import jekpro.tools.term.TermVar;
import java.io.IOException;
import java.io.Writer;
/**
* <p>Java code for the Call-out Call-in Solution Limiter example.</p>
* <p/>
* Warranty & Liability
* To the extent permitted by applicable law and unless explicitly
* otherwise agreed upon, XLOG Technologies GmbH makes no warranties
* regarding the provided information. XLOG Technologies GmbH assumes
* no liability that any problems might be solved with the information
* provided by XLOG Technologies GmbH.
* <p/>
* Rights & License
* All industrial property rights regarding the information - copyright
* and patent rights in particular - are the sole property of XLOG
* Technologies GmbH. If the company was not the originator of some
* excerpts, XLOG Technologies GmbH has at least obtained the right to
* reproduce, change and translate the information.
* <p/>
* Reproduction is restricted to the whole unaltered document. Reproduction
* of the information is only allowed for non-commercial uses. Selling,
* giving away or letting of the execution of the library is prohibited.
* The library can be distributed as part of your applications and libraries
* for execution provided this comment remains unchanged.
* <p/>
* Restrictions
* Only to be distributed with programs that add significant and primary
* functionality to the library. Not to be distributed with additional
* software intended to replace any components of the library.
* <p/>
* Trademarks
* Jekejeke is a registered trademark of XLOG Technologies GmbH.
*/
public class OutInLimit {
/* choice point data */
private final CallIn callin;
private int count = 0;
/**
* <p>Create a choice point data.</p>
*
* @param c The call-in.
*/
private OutInLimit(CallIn c) {
callin = c;
}
/**
* <p>Foreign predicate to limit solutions.</p>
*
* @param inter The call-in.
* @param callout The call-out object.
* @param goal The goal.
* @param max The maximum number of solutions to return.
* @return True if a result was found, otherwise false.
* @throws InterpreterException Passed down from the goal.
*/
public static boolean limit(Interpreter inter,
CallOut callout,
AbstractTerm goal, int max)
throws InterpreterException, InterpreterMessage {
OutInLimit limit;
if (callout.getFirst()) {
limit = new OutInLimit(inter.iterator(goal));
callout.setData(limit);
} else {
limit = (OutInLimit) callout.getData();
}
if (callout.getCleanup()) {
InterpreterException ex = callout.getException();
ex = limit.callin.cleanup(ex);
callout.setException(ex);
return true;
}
if (!(limit.count < max)) {
limit.callin.close();
return false;
}
if (limit.callin.hasNext()) {
limit.callin.next();
limit.count++;
callout.setRetry(true);
callout.setSpecial(true);
callout.setCutter(true);
return true;
}
return false;
}
/**
* <p>Runtime library variant of executing the example.</p>
*
* @param args The command line arguments.
* @throws InterpreterException Exception in Jekejeke Prolog execution.
* @throws InterpreterMessage Message in Jekejeke Prolog execution.
* @throws IOException Problem writing to current output.
*/
public static void main(String[] args) throws InterpreterException,
InterpreterMessage, IOException {
Knowledgebase know = new Knowledgebase(ToolkitLibrary.DEFAULT);
Interpreter inter = know.iterable();
Knowledgebase.initKnowledgebase(inter);
Object foreignGoal = inter.parseTerm("use_package(foreign(" +
"jekpro/tools/call))");
inter.iterator(foreignGoal).next().close();
foreignGoal = inter.parseTerm("use_package(foreign(" +
"jekpro/tools/term))");
inter.iterator(foreignGoal).next().close();
foreignGoal = inter.parseTerm("foreign(employee/1, " +
"'example03.OutTable', employee('CallOut'))");
inter.iterator(foreignGoal).next().close();
foreignGoal = inter.parseTerm("foreign(limit/2, " +
"'example05.OutInLimit', limit('Interpreter', 'CallOut'," +
"'AbstractTerm', 'int'))");
inter.iterator(foreignGoal).next().close();
TermVar employeeVar = new TermVar();
TermCompound employeeGoal = new TermCompound("employee", employeeVar);
TermCompound limitGoal = new TermCompound("limit", employeeGoal, 3);
Writer wr = (Writer) inter.getProperty(ToolkitLibrary.PROP_SYS_CUR_OUTPUT);
CallIn callin = inter.iterator(limitGoal);
while (callin.hasNext()) {
callin.next();
wr.write(inter.unparseTerm(0, employeeVar));
wr.write('\n');
wr.flush();
}
wr.write('\n');
wr.flush();
limitGoal = new TermCompound("limit", employeeGoal, 4);
callin = inter.iterator(limitGoal);
callin.next();
wr.write(inter.unparseTerm(0, employeeVar));
wr.write('\n');
wr.flush();
callin.close();
wr.write('\n');
wr.flush();
limitGoal = new TermCompound("limit", employeeGoal, 6);
callin = inter.iterator(limitGoal);
while (callin.hasNext()) {
callin.next();
wr.write(inter.unparseTerm(0, employeeVar));
wr.write('\n');
wr.flush();
}
}
}

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