Helper ChoiceDefined

Jan Burse, created Oct 18. 2019
package jekpro.model.inter;
import jekpro.model.molec.*;
import jekpro.model.rope.*;
import jekpro.tools.term.SkelCompound;
import jekpro.tools.term.SkelVar;
/**
* <p>The class provides a choice point for defined predicates.</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
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* 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 ChoiceDefined extends AbstractChoice {
protected int at;
protected final Clause[] list;
protected final AbstractUndo mark;
/**
* <p>Create pick choice.</p>
*
* @param n The molec.
* @param a The position.
* @param c The clause list.
* @param m The mark.
*/
ChoiceDefined(AbstractChoice n, int a,
Clause[] c,
CallFrame u, AbstractUndo m) {
super(n, u);
at = a;
list = c;
mark = m;
}
/**
* <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 predicate succeeded, otherwise false.
* @throws EngineException Shit happens.
*/
public boolean moniNext(Engine en)
throws EngineException {
/* remove choice point */
en.choices = next;
en.number--;
/* undo bindings */
en.contskel = goaldisplay.contskel;
en.contdisplay = goaldisplay.contdisplay;
en.fault = null;
en.releaseBind(mark);
if (en.fault != null)
throw en.fault;
Object t = ((Goal) goaldisplay.contskel).term;
Display d = goaldisplay.contdisplay.disp;
/* inlined deref */
BindUniv b1;
while (t instanceof SkelVar &&
(b1 = d.bind[((SkelVar) t).id]).display != null) {
t = b1.skel;
d = b1.display;
}
Clause clause;
Display d2 = goaldisplay.disp;
/* search rope */
for (; ; ) {
clause = list[at++];
d2.setSize(clause.sizerule);
if (clause.intargs == null ||
AbstractDefined.unifyDefined(((SkelCompound) t).args, d,
((SkelCompound) clause.head).args, d2,
clause.intargs, en))
break;
/* end of cursor */
if (at == list.length)
return false;
/* undo bindings */
en.fault = null;
en.releaseBind(mark);
if (en.fault != null)
throw en.fault;
}
d2.vars = clause.vars;
if (at != list.length) {
if ((clause.flags & AbstractDefined.MASK_DEFI_NBDY) == 0)
goaldisplay.flags &= ~Directive.MASK_DIRE_LTGC;
/* reuse choice point */
en.choices = this;
en.number++;
en.contskel = clause;
en.contdisplay = goaldisplay;
return true;
} else if (clause.getNextRaw(en) != Success.DEFAULT) {
CallFrame dc = goaldisplay.getFrame(en);
if ((clause.flags & AbstractDefined.MASK_DEFI_NBDY) == 0)
dc.flags &= ~Directive.MASK_DIRE_LTGC;
dc.flags &= ~Directive.MASK_DIRE_MORE;
en.contskel = clause;
en.contdisplay = dc;
return true;
} else {
if ((clause.flags & AbstractDefined.MASK_DEFI_NBDY) == 0) {
if (d2.bind.length > 0)
d2.remTab(en);
}
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--;
goaldisplay.flags &= ~Directive.MASK_DIRE_MORE;
}
}

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