/**
* Copyright (c) 2013, Institute of Information Systems (Sven Groppe and contributors of LUPOSDATE), University of Luebeck
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
* following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice, this list of conditions and the following
* disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
* following disclaimer in the documentation and/or other materials provided with the distribution.
* - Neither the name of the University of Luebeck nor the names of its contributors may be used to endorse or promote
* products derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package lupos.datastructures.patriciatrie.diskseq;
import java.util.List;
import lupos.datastructures.patriciatrie.Trie;
import lupos.datastructures.patriciatrie.TrieSet;
import lupos.datastructures.patriciatrie.diskseq.nodemanager.SeqNodeManager;
import lupos.datastructures.patriciatrie.exception.TrieNotCopyableException;
import lupos.datastructures.patriciatrie.exception.TrieNotMergeableException;
import lupos.datastructures.patriciatrie.node.Node;
import lupos.datastructures.patriciatrie.node.NodeHelper;
/**
* This class implements a special disk based behavior for a trie for set of strings.
*
* It can be used to store intermediary results on disk, that can be merged into
* a DBTrie or a RBTrie later.
*
* However, because of its underlying data structure, it is not suited for the
* basic operations add/remove.
*
* Merging is possible, but it breaks to possibility to convert this trie back
* into a RBTrie or DBTrie, because the values of numberOfEntries for the
* children will be wrong.
*/
public class DBSeqTrieSet extends TrieSet {
/**
* Name of the file, that holds this trie.
*/
protected String fileName;
/**
* Node Manager that manages write and read operations.
*/
protected SeqNodeManager nodeManager;
/**
* Constructor
*
* @param fileName
* Name of the file for this Trie
*
* @param mode the mode of this trie
*/
public DBSeqTrieSet(final String fileName) {
super();
this.fileName = fileName;
this.nodeManager = new SeqNodeManager(fileName);
}
@Override
public void copy(final Trie trie) throws TrieNotCopyableException {
if (!trie.hasCompleteMetadata()){
throw new TrieNotCopyableException();
}
this.nodeManager.clear();
this.nodeManager.writeNextNodeRecursive(DBSeqNode.deSerializer, trie.getRootNode());
this.prepareForReading();
}
/**
* Resets the InputStream, that is responsible for the retrieval of the nodes from the underlying filesystem.
*
* This method must be called before trying to merge this trie into another.
*/
@Override
protected void prepareForReading() {
this.nodeManager.readAgain();
this.setRootNode(this.nodeManager.readNextNode(DBSeqNode.deSerializer));
}
@Override
public void release() {
this.nodeManager.close();
this.nodeManager.release();
this.nodeManager = null;
super.release();
}
@Override
protected Node createNodeInstance() {
return new DBSeqNode(this.nodeManager);
}
@Override
protected Node createRootNodeInstance() {
throw new UnsupportedOperationException(); }
@Override
protected void changeRootNode(final Node rootNodeParam) {
this.nodeManager.writeRootNodeAgain(DBSeqNode.deSerializer, rootNodeParam);
}
@Override
public void clear() {
// TODO Implementieren
}
@Override
public boolean add(final String key) {
throw new UnsupportedOperationException();
}
@Override
public String get(final int index) {
throw new UnsupportedOperationException();
}
@Override
public int getIndex(final String key) {
throw new UnsupportedOperationException();
}
@Override
public boolean remove(final String key) {
throw new UnsupportedOperationException();
}
@Override
public void merge(final List<? extends Trie> tries) throws TrieNotMergeableException {
/*
* This trie must be empty, because the file, that contains the original
* elements, will be overwritten during the merge process. If this trie
* was not empty, there would be unpredictable side effects because the
* Input- and OutputStreams will be continuously reset.
*/
if (this.size() > 0){
System.err.println("Warning: Calling DBSeqTrie.merge() on a non-empty DBSeqTrie does not work. All entries from this DBSeqTrie will be removed before merging.");
}
this.setRootNode(null);
this.nodeManager.setCompleteMetadata(false);
this.nodeManager.clear();
this.merge(tries, false);
this.prepareForReading();
}
@Override
public boolean hasCompleteMetadata() {
return this.nodeManager.hasCompleteMetadata();
}
@Override
public int getNodeCount() {
throw new UnsupportedOperationException();
}
@Override
protected void mergeAfterCheck(final Node root, final List<Node> nodesToMerge){
NodeHelper.mergeSeqSet((DBSeqNode) root, nodesToMerge);
}
}