/**
* Innermost method for a reduction rule. Implementation of the abstract method from superclass.
*
* @net YNet to perform reduction
* @element an for consideration. returns a reduced YNet or null if a given net cannot be reduced.
*/
public YNet reduceElement(YNet net, YExternalNetElement nextElement) {
YNet reducedNet = net;
if (nextElement instanceof YCondition) {
YCondition condition = (YCondition) nextElement;
Set postSet = condition.getPostsetElements();
Set preSet = condition.getPresetElements();
// \pre{p} = 1, \post{p} = 1
if (preSet.size() == 1 && postSet.size() == 1) {
YTask t = (YTask) preSet.toArray()[0];
YTask u = (YTask) postSet.toArray()[0];
Set preSetOfu = u.getPresetElements();
Set postSetOfu = u.getPostsetElements();
// t,u and p are not reset
// u does not have reset arcs
Set postSetOft = new HashSet(t.getPostsetElements());
postSetOft.retainAll(postSetOfu);
if (t.getSplitType() == YTask._AND
&& u.getSplitType() == YTask._AND
&& preSetOfu.size() == 1
&& u.getRemoveSet().isEmpty()
&& t.getCancelledBySet().isEmpty()
&& u.getCancelledBySet().isEmpty()
&& condition.getCancelledBySet().isEmpty()
&& (!checkReset(postSetOfu))
&& postSetOft.isEmpty()) {
// set postflows from u to t
Iterator postFlowIter = postSetOfu.iterator();
while (postFlowIter.hasNext()) {
YExternalNetElement next = (YExternalNetElement) postFlowIter.next();
t.addPostset(new YFlow(t, next));
}
// remove condition from postset of t
t.removePostsetFlow(new YFlow(condition, t));
reducedNet.removeNetElement(condition);
reducedNet.removeNetElement(u);
t.addToYawlMappings(condition);
t.addToYawlMappings(condition.getYawlMappings());
t.addToYawlMappings(u);
t.addToYawlMappings(u.getYawlMappings());
return reducedNet;
} // if nested
} // if - size 1
} // endif - condition
return null;
}
