// Copyright 2017 JanusGraph Authors
//
// Licensed 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.janusgraph.graphdb.query.vertex;
import com.carrotsearch.hppc.LongArrayList;
import org.janusgraph.core.JanusGraphVertex;
import org.janusgraph.core.VertexList;
import org.janusgraph.graphdb.transaction.StandardJanusGraphTx;
import org.janusgraph.util.datastructures.AbstractLongListUtil;
import java.util.Arrays;
import java.util.Iterator;
import java.util.NoSuchElementException;
/**
* An implementation of {@link VertexListInternal} that stores only the vertex ids
* and simply wraps an {@link LongArrayList} and keeps a boolean flag to remember whether this list is in sort order.
* In addition, we need a transaction reference in order to construct actual vertex references on request.
* </p>
* This is a more efficient way to represent a vertex result set but only applies to loaded vertices that have ids.
* So, compared to {@link VertexArrayList} this is an optimization for the special use case that a vertex is loaded.
*
* @author Matthias Broecheler (me@matthiasb.com)
*/
public class VertexLongList implements VertexListInternal {
private final StandardJanusGraphTx tx;
private LongArrayList vertices;
private boolean sorted;
public VertexLongList(StandardJanusGraphTx tx) {
this(tx,new LongArrayList(10),true);
}
public VertexLongList(StandardJanusGraphTx tx, LongArrayList vertices, boolean sorted) {
assert !sorted || AbstractLongListUtil.isSorted(vertices);
this.tx = tx;
this.vertices = vertices;
this.sorted = sorted;
}
@Override
public void add(JanusGraphVertex n) {
if (!vertices.isEmpty()) sorted = sorted && vertices.get(vertices.size()-1)<=n.longId();
vertices.add(n.longId());
}
@Override
public long getID(int pos) {
return vertices.get(pos);
}
@Override
public LongArrayList getIDs() {
return vertices;
}
@Override
public JanusGraphVertex get(int pos) {
return tx.getInternalVertex(getID(pos));
}
@Override
public void sort() {
if (sorted) return;
Arrays.sort(vertices.buffer,0,vertices.size());
sorted = true;
}
@Override
public boolean isSorted() {
return sorted;
}
@Override
public VertexList subList(int fromPosition, int length) {
LongArrayList subList = new LongArrayList(length);
subList.add(vertices.buffer, fromPosition, length);
assert subList.size()==length;
return new VertexLongList(tx,subList,sorted);
}
@Override
public int size() {
return vertices.size();
}
@Override
public void addAll(VertexList vertexlist) {
LongArrayList othervertexids = null;
if (vertexlist instanceof VertexLongList) {
othervertexids = ((VertexLongList) vertexlist).vertices;
} else if (vertexlist instanceof VertexArrayList) {
VertexArrayList other = (VertexArrayList) vertexlist;
othervertexids = new LongArrayList(other.size());
for (int i = 0; i < other.size(); i++) othervertexids.add(other.getID(i));
} else {
throw new IllegalArgumentException("Unsupported vertex-list: " + vertexlist.getClass());
}
if (sorted && vertexlist.isSorted()) {
//Merge join
vertices = AbstractLongListUtil.mergeSort(vertices,othervertexids);
} else {
sorted = false;
vertices.add(othervertexids.buffer, 0, othervertexids.size());
}
}
public VertexArrayList toVertexArrayList() {
VertexArrayList list = new VertexArrayList(tx);
for (int i=0;i<vertices.size();i++) {
list.add(get(i));
}
return list;
}
@Override
public Iterator<JanusGraphVertex> iterator() {
return new Iterator<JanusGraphVertex>() {
private int pos = -1;
@Override
public boolean hasNext() {
return (pos + 1) < size();
}
@Override
public JanusGraphVertex next() {
if (!hasNext()) throw new NoSuchElementException();
pos++;
return get(pos);
}
@Override
public void remove() {
throw new UnsupportedOperationException("Vertices cannot be removed from neighborhood list");
}
};
}
}