/**
* 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;
}
