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package knorxx.framework.generator.order;
import com.google.common.base.Joiner;
import com.google.common.base.Optional;
import java.util.ArrayList;
import java.util.List;
import java.util.Set;
import org.jgrapht.alg.CycleDetector;
import org.jgrapht.graph.DefaultEdge;
import org.jgrapht.graph.SimpleDirectedGraph;
import org.jgrapht.traverse.TopologicalOrderIterator;
/**
*
* @author sj
*/
public abstract class OrderSorter {
private Optional<OrderSorter> nextCollector = Optional.absent();
public OrderSorter() {
}
public OrderSorter(OrderSorter nextCollector) {
this.nextCollector = Optional.of(nextCollector);
}
public Set<OrderConstraint> getConstraints(List<Class<?>> classes) {
Set<OrderConstraint> result = getConstraintsInternal(classes);
if (nextCollector.isPresent()) {
result.addAll(nextCollector.get().getConstraintsInternal(classes));
}
return result;
}
protected abstract Set<OrderConstraint> getConstraintsInternal(List<Class<?>> classes);
public List<String> sort(List<Class<?>> classes) throws OrderSortCycleException {
List<String> result = new ArrayList<>();
SimpleDirectedGraph<String, DefaultEdge> graph = new SimpleDirectedGraph<>(DefaultEdge.class);
for (OrderConstraint orderConstraint : getConstraints(classes)) {
graph.addVertex(orderConstraint.getFirst());
graph.addVertex(orderConstraint.getSecond());
graph.addEdge(orderConstraint.getFirst(), orderConstraint.getSecond());
}
CycleDetector<String, DefaultEdge> cycleDetector = new CycleDetector<>(graph);
if(!cycleDetector.detectCycles()) {
for (TopologicalOrderIterator<String, DefaultEdge> iterator = new TopologicalOrderIterator<>(graph); iterator.hasNext();) {
result.add(iterator.next());
}
} else {
String cycles = Joiner.on(", ").join(cycleDetector.findCycles());
throw new OrderSortCycleException("The given order constraints contain (at least one) cycle. Cycles can only "
+ "be caused by static references because we have single inherintance only in Java (involved classes: '" + cycles + "').");
}
return result;
}
}
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