poi/src/java/org/apache/poi/hssf/record/DBCellRecord.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.hssf.record;

import org.apache.poi.util.LittleEndian;

/**
 * Title:        DBCell Record
 * Description:  Used by Excel and other MS apps to quickly find rows in the sheets.<P>
 * REFERENCE:  PG 299/440 Microsoft Excel 97 Developer's Kit (ISBN: 1-57231-498-2)<P>
 * @author Andrew C. Oliver (acoliver at apache dot org)
 * @author Jason Height
 * @version 2.0-pre
 */
public final class DBCellRecord extends Record {
    public final static int BLOCK_SIZE = 32;
    public final static short sid = 0xd7;
    private int               field_1_row_offset;
    private short[]           field_2_cell_offsets;

    public DBCellRecord()
    {
        field_2_cell_offsets = new short[0];
    }

    /**
     * Constructs a DBCellRecord and sets its fields appropriately
     * @param in the RecordInputstream to read the record from
     */
    public DBCellRecord(RecordInputStream in)
    {
        super(in);
    }

    protected void validateSid(short id)
    {
        if (id != sid)
        {
            throw new RecordFormatException("NOT A valid DBCell RECORD");
        }
    }

    protected void fillFields(RecordInputStream in)
    {
        field_1_row_offset   = in.readUShort();
        int size = in.remaining();        
        field_2_cell_offsets = new short[ size / 2 ];

        for (int i=0;i<field_2_cell_offsets.length;i++)
        {
            field_2_cell_offsets[ i ] = in.readShort();
        }
    }

    /**
     * sets offset from the start of this DBCellRecord to the start of the first cell in
     * the next DBCell block.
     *
     * @param offset    offset to the start of the first cell in the next DBCell block
     */
    public void setRowOffset(int offset)
    {
        field_1_row_offset = offset;
    }

    // need short list impl.
    public void addCellOffset(short offset)
    {
        if (field_2_cell_offsets == null)
        {
            field_2_cell_offsets = new short[ 1 ];
        }
        else
        {
            short[] temp = new short[ field_2_cell_offsets.length + 1 ];

            System.arraycopy(field_2_cell_offsets, 0, temp, 0,
                             field_2_cell_offsets.length);
            field_2_cell_offsets = temp;
        }
        field_2_cell_offsets[ field_2_cell_offsets.length - 1 ] = offset;
    }

    /**
     * gets offset from the start of this DBCellRecord to the start of the first cell in
     * the next DBCell block.
     *
     * @return rowoffset to the start of the first cell in the next DBCell block
     */
    public int getRowOffset()
    {
        return field_1_row_offset;
    }

    /**
     * return the cell offset in the array
     *
     * @param index of the cell offset to retrieve
     * @return celloffset from the celloffset array
     */
    public short getCellOffsetAt(int index)
    {
        return field_2_cell_offsets[ index ];
    }

    /**
     * get the number of cell offsets in the celloffset array
     *
     * @return number of cell offsets
     */
    public int getNumCellOffsets()
    {
        return field_2_cell_offsets.length;
    }

    public String toString()
    {
        StringBuffer buffer = new StringBuffer();

        buffer.append("[DBCELL]\n");
        buffer.append("    .rowoffset       = ")
            .append(Integer.toHexString(getRowOffset())).append("\n");
        for (int k = 0; k < getNumCellOffsets(); k++)
        {
            buffer.append("    .cell_" + k + "          = ")
                .append(Integer.toHexString(getCellOffsetAt(k))).append("\n");
        }
        buffer.append("[/DBCELL]\n");
        return buffer.toString();
    }

    public int serialize(int offset, byte [] data)
    {
        if (field_2_cell_offsets == null)
        {
            field_2_cell_offsets = new short[ 0 ];
        }
        LittleEndian.putShort(data, 0 + offset, sid);
        LittleEndian.putShort(data, 2 + offset,
                              (( short ) (4 + (getNumCellOffsets() * 2))));
        LittleEndian.putInt(data, 4 + offset, getRowOffset());
        for (int k = 0; k < getNumCellOffsets(); k++)
        {
            LittleEndian.putShort(data, 8 + 2*k + offset, getCellOffsetAt(k));
        }
        return getRecordSize();
    }

    public int getRecordSize()
    {
        return 8 + (getNumCellOffsets() * 2);
    }
    
    /**
     *  @returns the size of the group of <tt>DBCellRecord</tt>s needed to encode
     *  the specified number of blocks and rows
     */
    public static int calculateSizeOfRecords(int nBlocks, int nRows) {
        // One DBCell per block.
        // 8 bytes per DBCell (non variable section)
        // 2 bytes per row reference
        return nBlocks * 8 + nRows * 2;
    }

    public short getSid()
    {
        return sid;
    }

    public boolean isInValueSection()
    {
        return true;
    }
    public Object clone() {
        // TODO - make immutable.
        // this should be safe because only the instantiating code mutates these objects
        return this;
    }
}