/*
* Copyright 2015 Red Hat, Inc. and/or its affiliates.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.drools.core.beliefsystem.defeasible;
import org.drools.core.beliefsystem.BeliefSystem;
import org.drools.core.beliefsystem.jtms.JTMSBeliefSet;
import org.drools.core.beliefsystem.jtms.JTMSBeliefSetImpl.MODE;
import org.drools.core.common.EqualityKey;
import org.drools.core.common.InternalFactHandle;
import org.drools.core.common.LogicalDependency;
import org.drools.core.common.QueryElementFactHandle;
import org.drools.core.common.WorkingMemoryAction;
import org.drools.core.definitions.rule.impl.RuleImpl;
import org.drools.core.spi.PropagationContext;
import org.drools.core.util.Entry;
import org.drools.core.util.FastIterator;
import org.drools.core.util.LinkedListNode;
import org.kie.api.runtime.rule.FactHandle;
import java.util.Arrays;
import java.util.List;
public class DefeasibleBeliefSet<M extends DefeasibleMode<M>> implements JTMSBeliefSet<M> {
private BeliefSystem beliefSystem;
public static final String DEFEATS = Defeats.class.getSimpleName();
private static final FastIterator iterator = new IteratorImpl();
private InternalFactHandle rootHandle;
private M rootUndefeated;
private M tailUndefeated;
private int definitelyPosCount;
private int definitelyNegCount;
private int defeasiblyPosCount;
private int defeasiblyNegCount;
private int defeatedlyPosCount;
private int defeatedlyNegCount;
private static final int DEFINITELY_POS_BIT = 1;
private static final int DEFINITELY_NEG_BIT = 2;
private static final int DEFEASIBLY_POS_BIT = 4;
private static final int DEFEASIBLY_NEG_BIT = 8;
private static final int DEFEATEDLY_POS_BIT = 16;
private static final int DEFEATEDLY_NEG_BIT = 32;
private static final int POS_MASK = DEFINITELY_POS_BIT | DEFEASIBLY_POS_BIT | DEFEATEDLY_POS_BIT;
private static final int NEG_MASK = DEFINITELY_NEG_BIT | DEFEASIBLY_NEG_BIT | DEFEATEDLY_NEG_BIT;
private static final int WEAK_POS_MASK = DEFEASIBLY_POS_BIT | DEFEATEDLY_POS_BIT;
private static final int WEAK_NEG_MASK = DEFEASIBLY_NEG_BIT | DEFEATEDLY_NEG_BIT;
private int statusMask = 0;
private DefeasibilityStatus status;
public DefeasibleBeliefSet(BeliefSystem<M> beliefSystem, InternalFactHandle rootHandle) {
this.beliefSystem = beliefSystem;
this.rootHandle = rootHandle;
}
public BeliefSystem<M> getBeliefSystem() {
return beliefSystem;
}
public InternalFactHandle getFactHandle() {
return rootHandle;
}
public M getFirst() {
return rootUndefeated;
}
public DefeasibleMode<M> getLast() {
return tailUndefeated;
}
public void add( M newDep ) {
newDep.setStatus( resolveStatus( newDep ) );
RuleImpl rule = newDep.getLogicalDependency().getJustifier().getRule();
// first iterate to see if this new dep is defeated. If it's defeated, it can no longer impacts any deps
// if we checked what it defeats, and later this was defeated, we would have undo action. So we do the cheaper work first.
boolean wasDefeated = false;
for (DefeasibleMode<M> existingDep = rootUndefeated; existingDep != null; existingDep = existingDep.getNext()) {
wasDefeated = checkIsDefeated( newDep, rule, existingDep );
if (wasDefeated) {
existingDep.addDefeated( newDep );
break;
}
}
if (!wasDefeated) {
M stagedDeps = null;
for ( M existingDep = rootUndefeated; existingDep != null;) {
M next = existingDep.getNext();
if ( checkIsDefeated( existingDep, existingDep.getLogicalDependency().getJustifier().getRule(), newDep ) ) {
// fist remove it from the undefeated list
removeUndefeated( existingDep );
newDep.addDefeated( existingDep );
if (existingDep.getRootDefeated() != null) {
// build up the list of staged deps, that will need to be reprocessed
if (stagedDeps == null) {
stagedDeps = existingDep.getRootDefeated();
} else {
stagedDeps.setPrevious( existingDep.getTailDefeated() );
stagedDeps = existingDep.getRootDefeated();
}
}
existingDep.clearDefeated();
}
existingDep = next;
}
addUndefeated(newDep);
// now process the staged
reprocessDefeated(stagedDeps);
}
updateStatus();
}
private void reprocessDefeated( M deps ) {
for ( M dep = deps; dep != null; ) {
M next = dep.getNext();
dep.nullPrevNext(); // it needs to be removed, before it can be processed
add( dep ); // adding back in, effectively reprocesses the dep
dep = next;
}
}
public void remove( M dep) {
if (dep.getDefeatedBy() != null) {
// Defeated deps do not have defeated defeated lists of their own, so just remove.
DefeasibleMode<M> defeater = dep.getDefeatedBy();
defeater.removeDefeated(dep);
} else {
// ins undefeated, process it's defeated list if they exist
removeUndefeated(dep);
if (dep.getRootDefeated() != null) {
reprocessDefeated( dep.getRootDefeated() );
}
}
updateStatus();
}
private boolean checkIsDefeated( DefeasibleMode potentialInferior, RuleImpl rule, DefeasibleMode potentialSuperior ) {
if ( potentialSuperior.getDefeats() == null ) {
return false;
}
if ( potentialSuperior.getStatus() == DefeasibilityStatus.DEFINITELY && potentialInferior.getStatus() != DefeasibilityStatus.DEFINITELY ) {
return true;
}
// adds the references that defeat the current node
if (Arrays.binarySearch(potentialSuperior.getDefeats(), rule.getName()) >= 0 ||
Arrays.binarySearch(potentialSuperior.getDefeats(), rule.getPackage() + "." + rule.getName()) >= 0) {
if ( "neg".equals( potentialSuperior.getValue() ) ^ "neg".equals( potentialInferior.getValue() ) ) {
return true;
}
}
return false;
}
public void addUndefeated( M dep ) {
boolean pos = ! ( dep.getValue() != null && MODE.NEGATIVE.getId().equals( dep.getValue() ) );
switch( dep.getStatus() ) {
case DEFINITELY:
if ( pos ) {
definitelyPosCount++;
statusMask = statusMask | DEFINITELY_POS_BIT;
} else {
definitelyNegCount++;
statusMask = statusMask | DEFINITELY_NEG_BIT;
}
break;
case DEFEASIBLY:
if ( pos ) {
defeasiblyPosCount++;
statusMask = statusMask | DEFEASIBLY_POS_BIT;
} else {
defeasiblyNegCount++;
statusMask = statusMask | DEFEASIBLY_NEG_BIT;
}
break;
case DEFEATEDLY:
if ( pos ) {
defeatedlyPosCount++;
statusMask = statusMask | DEFEATEDLY_POS_BIT;
} else {
defeatedlyNegCount++;
statusMask = statusMask | DEFEATEDLY_NEG_BIT;
}
break;
case UNDECIDABLY:
throw new IllegalStateException("Individual logical dependencies cannot be undecidably");
}
if (rootUndefeated == null) {
rootUndefeated = dep;
tailUndefeated = dep;
} else {
if ( dep.getStatus() == DefeasibilityStatus.DEFINITELY ) {
// Strict dependencies at to the front
rootUndefeated.setPrevious(dep);
dep.setNext(rootUndefeated);
rootUndefeated = dep;
} else {
// add to end
tailUndefeated.setNext(dep);
dep.setPrevious(tailUndefeated);
tailUndefeated = dep;
}
}
}
public void removeUndefeated(DefeasibleMode dep) {
boolean pos = ! ( dep.getValue() != null && MODE.NEGATIVE.getId().equals( dep.getValue().toString() ) );
switch( dep.getStatus() ) {
case DEFINITELY:
if ( pos ) {
definitelyPosCount--;
if ( definitelyPosCount == 0 ) {
statusMask = statusMask ^ DEFINITELY_POS_BIT;
}
} else {
definitelyNegCount--;
if ( definitelyNegCount == 0 ) {
statusMask = statusMask ^ DEFINITELY_NEG_BIT;
}
}
break;
case DEFEASIBLY:
if ( pos ) {
defeasiblyPosCount--;
if ( defeasiblyPosCount == 0 ) {
statusMask = statusMask ^ DEFEASIBLY_POS_BIT;
}
} else {
defeasiblyNegCount--;
if ( defeasiblyNegCount == 0 ) {
statusMask = statusMask ^ DEFEASIBLY_NEG_BIT;
}
}
break;
case DEFEATEDLY:
if ( pos ) {
defeatedlyPosCount--;
if ( defeatedlyPosCount == 0 ) {
statusMask = statusMask ^ DEFEATEDLY_POS_BIT;
}
} else {
defeatedlyNegCount--;
if ( defeatedlyNegCount == 0 ) {
statusMask = statusMask ^ DEFEATEDLY_NEG_BIT;
}
}
break;
case UNDECIDABLY:
throw new IllegalStateException("Individual logical dependencies cannot be undecidably");
}
if (this.rootUndefeated == dep) {
removeFirst();
} else if (this.tailUndefeated == dep) {
removeLast();
} else {
dep.getPrevious().setNext(dep.getNext());
((DefeasibleMode)dep.getNext()).setPrevious(dep.getPrevious());
dep.nullPrevNext();
}
}
public M removeFirst() {
if (this.rootUndefeated == null) {
return null;
}
final M dep = this.rootUndefeated;
this.rootUndefeated = dep.getNext();
dep.setNext(null);
if (this.rootUndefeated != null) {
this.rootUndefeated.setPrevious(null);
} else {
this.tailUndefeated = null;
}
return dep;
}
public M removeLast() {
if (this.tailUndefeated == null) {
return null;
}
final M dep = this.tailUndefeated;
this.tailUndefeated = dep.getPrevious();
dep.setPrevious(null);
if (this.tailUndefeated != null) {
this.tailUndefeated.setNext(null);
} else {
this.rootUndefeated = this.tailUndefeated;
}
return dep;
}
public LinkedListNode getRootUndefeated() {
return this.rootUndefeated;
}
public LinkedListNode getTailUnDefeated() {
return this.tailUndefeated;
}
public boolean isEmpty() {
return rootUndefeated == null;
}
public int size() {
return definitelyPosCount + definitelyNegCount + defeasiblyPosCount + defeasiblyNegCount + defeatedlyPosCount + defeatedlyNegCount;
}
public int undefeatdSize() {
int i = 0;
for (DefeasibleMode existingNode = rootUndefeated; existingNode != null; existingNode = (DefeasibleMode) existingNode.getNext()) {
i++;
}
return i;
}
public void cancel(PropagationContext propagationContext) {
// get all but last, as that we'll do via the BeliefSystem, for cleanup
// note we don't update negative, conflict counters. It's needed for the last cleanup operation
FastIterator it = iterator();
for ( M node = getFirst(); node != tailUndefeated; ) {
M temp = (M) it.next(node); // get next, as we are about to remove it
LogicalDependency<M> dep = node.getLogicalDependency();
dep.getJustifier().getLogicalDependencies().remove( dep );
remove( node );
node = temp;
}
DefeasibleMode<M> node = getFirst();
LogicalDependency<M> dep = node.getLogicalDependency();
dep.getJustifier().getLogicalDependencies().remove( dep );
}
public void clear(PropagationContext propagationContext) {
}
public void setWorkingMemoryAction(WorkingMemoryAction wmAction) {
}
public boolean isDefinitelyPosProveable() {
return (statusMask & DEFINITELY_POS_BIT) != 0;
}
public boolean isDefinitelyNegProveable() {
return (statusMask & DEFINITELY_NEG_BIT) != 0;
}
public boolean isDefeasiblyPosProveable() {
return (statusMask & DEFEASIBLY_POS_BIT) != 0;
}
public boolean isDefeasiblyNegProveable() {
return (statusMask & DEFEASIBLY_NEG_BIT) != 0;
}
public boolean isDefeatedlyPosProveable() {
return (statusMask & DEFEATEDLY_POS_BIT) != 0;
}
public boolean isDefeatedlyNegProveable() {
return (statusMask & DEFEATEDLY_NEG_BIT) != 0;
}
public DefeasibilityStatus getStatus() {
return status;
}
public void updateStatus() {
if ( isDefinitelyPosProveable() ^ isDefinitelyNegProveable() ) {
status = DefeasibilityStatus.DEFINITELY;
return;
}
if ( isConflicting() ) {
status = DefeasibilityStatus.UNDECIDABLY;
return;
}
if ( isDefeasiblyPosProveable() ^ isDefeasiblyNegProveable() ) {
status = DefeasibilityStatus.DEFEASIBLY;
return;
}
if ( isDefeatedlyPosProveable() ^ isDefeatedlyNegProveable() ) {
status = DefeasibilityStatus.DEFEATEDLY;
return;
}
status = DefeasibilityStatus.UNDECIDABLY;
}
public boolean isNegated() {
return ((statusMask & POS_MASK ) == 0 ) && ((statusMask & NEG_MASK ) != 0 );
}
public boolean isPositive() {
return ((statusMask & POS_MASK ) != 0 ) && ((statusMask & NEG_MASK ) == 0 );
}
public boolean isConflicting() {
return ((statusMask & POS_MASK ) != 0 ) && ((statusMask & NEG_MASK ) != 0 );
}
public boolean isDecided() {
return getStatus() != DefeasibilityStatus.UNDECIDABLY && getStatus() != DefeasibilityStatus.DEFEATEDLY;
}
public FastIterator iterator() {
return iterator;
}
private static class IteratorImpl implements FastIterator {
public Entry next(Entry object) {
DefeasibleMode dep = (DefeasibleMode) object;
if ( dep.getRootDefeated() != null ) {
// try going down the list of defeated first
return dep.getRootDefeated();
}
if ( dep.getNext() != null ) {
return dep.getNext();
}
if ( dep.getDefeatedBy() != null ) {
// go back up to the parent undefeated, and try the next undefeated
return dep.getDefeatedBy().getNext();
}
return null; // nothing more to iterate too.
}
public boolean isFullIterator() {
return true;
}
}
private DefeasibilityStatus resolveStatus( DefeasibleMode node ) {
List<? extends FactHandle> premise = node.getLogicalDependency().getJustifier().getFactHandles();
DefeasibilityStatus status = DefeasibilityStatus.resolve( node.getValue() );
if ( status == null ) {
DefeasibleRuleNature defeasibleType = DefeasibleRuleNature.STRICT;
if ( node.getLogicalDependency().getJustifier().getRule().getMetaData().containsKey( DefeasibleRuleNature.DEFEASIBLE.getLabel() ) ) {
defeasibleType = DefeasibleRuleNature.DEFEASIBLE;
} else if ( node.getLogicalDependency().getJustifier().getRule().getMetaData().containsKey( DefeasibleRuleNature.DEFEATER.getLabel() ) ) {
defeasibleType = DefeasibleRuleNature.DEFEATER;
}
switch ( defeasibleType ) {
case DEFEASIBLE :
status = checkDefeasible(premise);
break;
case DEFEATER :
status = checkDefeater(premise);
break;
case STRICT :
default :
status = checkStrict(premise );
break;
}
}
return status;
}
private DefeasibilityStatus checkDefeasible( List<? extends FactHandle> premise ) {
return DefeasibilityStatus.DEFEASIBLY;
}
private DefeasibilityStatus checkDefeater( List<? extends FactHandle> premise ) {
return DefeasibilityStatus.DEFEATEDLY;
}
private DefeasibilityStatus checkStrict( List<? extends FactHandle> premise ) {
// The rule is strict. To prove that the derivation is strict we have to check that all the premises are
// either facts or strictly proved facts
for ( FactHandle h : premise ) {
if ( h instanceof QueryElementFactHandle ) {
return DefeasibilityStatus.DEFINITELY;
}
EqualityKey key = ((InternalFactHandle) h).getEqualityKey();
if ( key != null && key.getStatus() == EqualityKey.JUSTIFIED ) {
//DefeasibleBeliefSet bs = (DefeasibleBeliefSet) getTruthMaintenanceSystem().getJustifiedMap().get(((DefaultFactHandle) h).getId());
DefeasibleBeliefSet bs = (DefeasibleBeliefSet) key.getBeliefSet();
if ( bs.getStatus() != DefeasibilityStatus.DEFINITELY ) {
// to make a fact "definitely provable", all the supporting non-factual premises must be definitely provable.
return DefeasibilityStatus.DEFEASIBLY;
}
}
// else it's a fact, so it's a good candidate for definite entailment
}
return DefeasibilityStatus.DEFINITELY;
}
}