/**
* Extracts the morphism from rule nodes to input graph nodes corresponding to the transition's
* input parameters.
*
* @return if {@code null}, the binding cannot be constructed and so the rule cannot match
*/
private RuleToHostMap extractBinding(Step step) {
RuleToHostMap result = this.state.getGraph().getFactory().createRuleToHostMap();
Object[] sourceValues = this.state.getActualValues();
for (Assignment assign : step.getEnterAssignments()) {
sourceValues = assign.compute(sourceValues);
}
for (Pair<Var, Binding> entry : step.getRuleSwitch().getCallBinding()) {
Binding bind = entry.two();
HostNode value;
if (bind == null) {
// this corresponds to an output parameter of the call
continue;
}
switch (bind.getSource()) {
case CONST:
value = bind.getValue().getNode();
break;
case VAR:
value = Valuator.get(sourceValues, bind);
break;
default:
assert false;
value = null;
}
RuleNode ruleNode = entry.one().getRuleNode();
if (isCompatible(ruleNode, value)) {
result.putNode(ruleNode, value);
} else {
result = null;
break;
}
}
return result;
}
/**
* Returns the set of matching events for a given control step.
*
* @param step the control step for which matches are to be found; non-{@code null}
*/
public MatchResultSet computeMatches(final Step step) {
final MatchResultSet result = new MatchResultSet();
if (DEBUG) {
System.out.printf("Matches for %s, %s%n ", this.state, this.state.getGraph());
}
assert step != null;
// there are three reasons to want to use the parent matches: to
// save matching time, to reuse added nodes, and to find confluent
// diamonds. The first is only relevant if the rule is not (re)enabled,
// the third only if the parent match target is already closed
final boolean isDisabled = isDisabled(step.getRuleCall());
boolean isModifying = step.isModifying();
if (!isDisabled) {
for (GraphTransition trans : this.parentTransMap) {
if (trans instanceof RuleTransition) {
RuleTransition ruleTrans = (RuleTransition) trans;
if (ruleTrans.getEvent().getRule().equals(step.getRule())) {
MatchResult match = ruleTrans.getKey();
if (isModifying) {
// we can reuse the event but not the control step
match = new MatchResult(match.getEvent(), step);
}
result.add(match);
if (DEBUG) {
System.out.print(" T" + System.identityHashCode(trans.getEvent()));
}
}
}
}
}
if (isDisabled || isEnabled(step.getRuleCall())) {
// the rule was possibly enabled afresh, so we have to add the fresh
// matches
RuleToHostMap boundMap = extractBinding(step);
if (boundMap != null) {
final Record record = this.record;
Visitor<Proof, Boolean> eventCollector =
new Visitor<Proof, Boolean>(false) {
@Override
protected boolean process(Proof object) {
RuleEvent event = record.getEvent(object);
// only look up the event in the parent map if
// the rule was disabled, as otherwise the result
// already contains all relevant parent results
MatchResult match = new MatchResult(event, step);
if (isDisabled) {
match = getParentTrans(match);
}
result.add(match);
if (DEBUG) {
System.out.print(" E" + System.identityHashCode(match.getEvent()));
checkEvent(match.getEvent());
}
setResult(true);
return true;
}
};
step.getRule().traverseMatches(this.state.getGraph(), boundMap, eventCollector);
}
}
if (DEBUG) {
System.out.println();
}
return result;
}