Helper ChoiceForeign

Jan Burse, created Jun 19. 2019
package jekpro.tools.foreign;
import jekpro.model.inter.AbstractChoice;
import jekpro.model.inter.Engine;
import jekpro.model.molec.*;
import jekpro.model.rope.Goal;
import jekpro.model.rope.Intermediate;
import jekpro.tools.array.Types;
import jekpro.tools.call.CallOut;
import jekpro.tools.call.InterpreterException;
import jekpro.tools.term.AbstractSkel;
import jekpro.tools.term.AbstractTerm;
import jekpro.tools.term.SkelCompound;
import jekpro.tools.term.SkelVar;
import static jekpro.tools.array.AbstractLense.MASK_METH_FUNC;
/**
* <p>The class represents a choice point for a foreign predicate.
* Foreign predicate objects cannot be directly constructed by the
* application programmer. They are created by the method defineForeign()
* in the interpreter or by the foreign/3 builtin.</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.
*/
final class ChoiceForeign extends AbstractChoice {
CallOut co;
MemberMethodNondet del;
Object obj;
Object[] args;
AbstractUndo mark;
Intermediate goalskel;
/**
* <p>Creata choice foreign.</p>
*
* @param n The parent choice.
*/
ChoiceForeign(AbstractChoice n, CallFrame u) {
super(n, u);
}
/**
* <p>Logically evaluate a term in a list of goals for an additional time.</p>
* <p>The result is returned via the contskel and contdisplay of the engine.</p>
*
* @param en The engine.
* @return True if the foreign predicate succeeded, otherwise false.
* @throws EngineException FFI error.
* @throws EngineMessage FFI error.
*/
public final boolean moniNext(Engine en)
throws EngineException, EngineMessage {
/* remove choice point */
en.choices = next;
en.number--;
en.contskel = goalskel;
en.contdisplay = goaldisplay;
if ((co.flags & CallOut.MASK_CALL_SPECI) == 0) {
en.fault = null;
en.releaseBind(mark);
if (en.fault != null)
throw en.fault;
}
Intermediate ir = goalskel;
Object term = ((Goal) ir).term;
Display ref = goaldisplay.disp;
if ((ir.flags & Goal.MASK_GOAL_NAKE) != 0) {
/* inlined deref */
BindUniv b1;
while (term instanceof SkelVar &&
(b1 = ref.bind[((SkelVar) term).id]).display != null) {
term = b1.skel;
ref = b1.display;
}
}
co.flags &= ~CallOut.MASK_CALL_FIRST;
for (; ; ) {
co.flags &= ~CallOut.MASK_CALL_RETRY;
co.flags &= ~CallOut.MASK_CALL_SPECI;
co.flags &= ~CallOut.MASK_CALL_CUTTR;
Object res = AbstractMember.invokeMethod(del.method, obj, args, en);
if ((del.subflags & MASK_METH_FUNC) != 0) {
res = Types.normJava(del.encoderet, res);
} else {
res = Types.noretNormJava(del.encoderet, res);
}
if (res == null)
return false;
Display d = AbstractTerm.getDisplay(res);
Object[] help;
boolean ext = d.getAndReset();
if (res != AbstractSkel.VOID_OBJ &&
!en.unifyTerm((help = ((SkelCompound) term).args)[
help.length - 1], ref,
AbstractTerm.getSkel(res), d)) {
if ((co.flags & CallOut.MASK_CALL_RETRY) == 0)
return false;
if ((co.flags & CallOut.MASK_CALL_SPECI) == 0) {
en.fault = null;
en.releaseBind(mark);
if (en.fault != null)
throw en.fault;
}
} else {
if (ext)
d.remTab(en);
if ((co.flags & CallOut.MASK_CALL_RETRY) != 0) {
/* meta argument change */
if ((co.flags & CallOut.MASK_CALL_SPECI) != 0)
next = en.choices;
/* reuse choice point */
en.choices = this;
en.number++;
}
return true;
}
}
}
/**
* <p>Free data used to logically evaluate a term an additional time.</p>
* <p>The current exception is passed via the engine fault.</p>
* <p>The new current exception is returned via the engine fault.</p>
* <p>The current contskel and contdisplay of the engine is not changed.</p>
*
* @param en The engine.
*/
public final void moniCut(Engine en) {
/* remove choice point */
en.choices = next;
en.number--;
if ((co.flags & CallOut.MASK_CALL_CUTTR) == 0)
return;
/* backup continuation */
Intermediate r = en.contskel;
CallFrame u = en.contdisplay;
en.contskel = goalskel;
en.contdisplay = goaldisplay;
if (en.fault != null) {
co.setException(new InterpreterException(en.fault));
} else {
co.setException(null);
}
try {
co.flags &= ~CallOut.MASK_CALL_FIRST;
co.flags |= CallOut.MASK_CALL_CLEAN;
AbstractMember.invokeMethod(del.method, obj, args, en);
InterpreterException ie = co.getException();
en.fault = (ie != null ? (EngineException) ie.getException() : null);
} catch (EngineException x) {
InterpreterException ie = co.getException();
en.fault = (ie != null ? (EngineException) ie.getException() : null);
if (en.fault != null) {
en.fault = new EngineException(en.fault, x);
} else {
en.fault = x;
}
} catch (EngineMessage y) {
InterpreterException ie = co.getException();
en.fault = (ie != null ? (EngineException) ie.getException() : null);
EngineException x = new EngineException(y, EngineException.fetchStack(en));
if (en.fault != null) {
en.fault = new EngineException(en.fault, x);
} else {
en.fault = x;
}
}
/* restore continuation */
en.contskel = r;
en.contdisplay = u;
}
}

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