/* Copyright (C) 2004 - 2006 db4objects Inc. http://www.db4o.com
This file is part of the db4o open source object database.
db4o is free software; you can redistribute it and/or modify it under
the terms of version 2 of the GNU General Public License as published
by the Free Software Foundation and as clarified by db4objects' GPL
interpretation policy, available at
http://www.db4o.com/about/company/legalpolicies/gplinterpretation/
Alternatively you can write to db4objects, Inc., 1900 S Norfolk Street,
Suite 350, San Mateo, CA 94403, USA.
db4o is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
package com.db4o.internal;
import com.db4o.foundation.Tree;
/**
* @exclude
*/
public final class TreeReader
{
private final Readable i_template;
private final Buffer i_bytes;
private int i_current = 0;
private int i_levels = 0;
private int i_size;
private boolean i_orderOnRead;
public TreeReader(Buffer a_bytes, Readable a_template) {
this(a_bytes, a_template, false);
}
public TreeReader(Buffer a_bytes, Readable a_template, boolean a_orderOnRead) {
i_template = a_template;
i_bytes = a_bytes;
i_orderOnRead = a_orderOnRead;
}
public Tree read() {
return read(i_bytes.readInt());
}
public Tree read(int a_size){
i_size = a_size;
if(i_size > 0){
if(i_orderOnRead){
Tree tree = null;
for (int i = 0; i < i_size; i++) {
tree = Tree.add(tree, (Tree)i_template.read(i_bytes));
}
return tree;
}
while ((1 << i_levels) < (i_size + 1)){
i_levels ++;
}
return linkUp(null, i_levels);
}
return null;
}
private final Tree linkUp(Tree a_preceding, int a_level){
Tree node = (Tree)i_template.read(i_bytes);
i_current++;
node._preceding = a_preceding;
node._subsequent = linkDown(a_level + 1);
node.calculateSize();
if(i_current < i_size){
return linkUp(node, a_level - 1);
}
return node;
}
private final Tree linkDown(int a_level){
if(i_current < i_size){
i_current++;
if(a_level < i_levels) {
Tree preceding = linkDown(a_level + 1);
Tree node = (Tree)i_template.read(i_bytes);
node._preceding = preceding;
node._subsequent = linkDown(a_level + 1);
node.calculateSize();
return node;
}
return (Tree)i_template.read(i_bytes);
}
return null;
}
}