PropertyTable.java

/* ====================================================================
   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.poi.poifs.property;

import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Stack;

import org.apache.poi.poifs.storage.BlockWritable;
import org.apache.poi.poifs.storage.RawDataBlockList;

/**
 * This class embodies the Property Table for the filesystem; this is
 * basically the dsirectory for all of the documents in the
 * filesystem.
 *
 * @author Marc Johnson (mjohnson at apache dot org)
 */
public final class PropertyTable implements BlockWritable {
    private List<Property>    _properties;
    private BlockWritable[]   _blocks;

    public PropertyTable()
    {
        _properties  = new ArrayList<>();
        addProperty(new RootProperty());
        _blocks = null;
    }

    /**
     * reading constructor (used when we've read in a file and we want
     * to extract the property table from it). Populates the
     * properties thoroughly
     *
     * @param startBlock the first block of the property table
     * @param blockList the list of blocks
     *
     * @exception IOException if anything goes wrong (which should be
     *            a result of the input being NFG)
     */
    public PropertyTable(
                         final int startBlock,
                         final RawDataBlockList blockList)
        throws IOException
    {
        _blocks      = null;
        _properties  =
            PropertyFactory
                .convertToProperties(blockList.fetchBlocks(startBlock, -1));
        populatePropertyTree(( DirectoryProperty ) _properties.get(0));
    }

    /**
     * Add a property to the list of properties we manage
     *
     * @param property the new Property to manage
     */
    public void addProperty(Property property)
    {
        _properties.add(property);
    }

    /**
     * Remove a property from the list of properties we manage
     *
     * @param property the Property to be removed
     */
    public void removeProperty(final Property property)
    {
        _properties.remove(property);
    }

    /**
     * Get the root property
     *
     * @return the root property
     */
    public RootProperty getRoot()
    {

        // it's always the first element in the List
        return ( RootProperty ) _properties.get(0);
    }

    private void populatePropertyTree(DirectoryProperty root)
        throws IOException
    {
        int index = root.getChildIndex();

        if (!Property.isValidIndex(index))
        {

            // property has no children
            return;
        }
        Stack<Property> children = new Stack<>();

        children.push(_properties.get(index));
        while (!children.empty())
        {
            Property property = children.pop();

            root.addChild(property);
            if (property.isDirectory())
            {
                populatePropertyTree(( DirectoryProperty ) property);
            }
            index = property.getPreviousChildIndex();
            if (Property.isValidIndex(index))
            {
                children.push(_properties.get(index));
            }
            index = property.getNextChildIndex();
            if (Property.isValidIndex(index))
            {
                children.push(_properties.get(index));
            }
        }
    }

    /**
     * Write the storage to an OutputStream
     *
     * @param stream the OutputStream to which the stored data should
     *               be written
     *
     * @exception IOException on problems writing to the specified
     *            stream
     */
    public void writeBlocks(final OutputStream stream)
        throws IOException
    {
        if (_blocks != null)
        {
            for (int j = 0; j < _blocks.length; j++)
            {
                _blocks[ j ].writeBlocks(stream);
            }
        }
    }
}