/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* 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.apache.tajo.util.graph;
import java.util.ArrayList;
public class DirectedGraphCursor<V,E> {
private DirectedGraph<V,E> graph;
private ArrayList<V> orderedVertices = new ArrayList<>();
private int cursor = 0;
public DirectedGraphCursor(DirectedGraph<V, E> graph, V startVertex) {
this.graph = graph;
buildOrder(startVertex);
}
public int size() {
return orderedVertices.size();
}
private void buildOrder(V current) {
if (!graph.isLeaf(current)) {
for (V child : graph.getChilds(current)) {
buildOrder(child);
}
}
orderedVertices.add(current);
}
public boolean hasNext() {
return cursor < orderedVertices.size();
}
public V nextBlock() {
return orderedVertices.get(cursor++);
}
public V peek() {
return orderedVertices.get(cursor);
}
public V peek(int skip) {
return orderedVertices.get(cursor + skip);
}
public void reset() {
cursor = 0;
}
}