
/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2003 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. 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.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache POI" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
 *    written permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    "Apache POI", nor may "Apache" appear in their name, without
 *    prior written permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED 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 APACHE SOFTWARE FOUNDATION OR
 * ITS 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

/*
 * Cell.java
 *
 * Created on September 30, 2001, 3:46 PM
 */
package org.apache.poi.hssf.usermodel;

import org.apache.poi.hssf.model.Workbook;
import org.apache.poi.hssf.model.Sheet;
import org.apache.poi.hssf.model.FormulaParser;
import org.apache.poi.hssf.record.CellValueRecordInterface;
import org.apache.poi.hssf.record.Record;
import org.apache.poi.hssf.record.FormulaRecord;
import org.apache.poi.hssf.record.LabelSSTRecord;
import org.apache.poi.hssf.record.NumberRecord;
import org.apache.poi.hssf.record.BlankRecord;
import org.apache.poi.hssf.record.BoolErrRecord;
import org.apache.poi.hssf.record.ExtendedFormatRecord;
import org.apache.poi.hssf.record.aggregates.FormulaRecordAggregate;
import org.apache.poi.hssf.record.formula.Ptg;
import org.apache.poi.hssf.util.SheetReferences;

//import org.apache.poi.hssf.record.formula.FormulaParser;

import java.util.Date;
import java.util.Calendar;

/**
 * High level representation of a cell in a row of a spreadsheet.
 * Cells can be numeric, formula-based or string-based (text).  The cell type
 * specifies this.  String cells cannot conatin numbers and numeric cells cannot
 * contain strings (at least according to our model).  Client apps should do the
 * conversions themselves.  Formula cells are treated like string cells, simply
 * containing a formula string.  They'll be rendered differently.
 * <p>
 * Cells should have their number (0 based) before being added to a row.  Only
 * cells that have values should be added.
 * <p>
 * NOTE: the alpha won't be implementing formulas
 *
 * @author  Andrew C. Oliver (acoliver at apache dot org)
 * @author  Dan Sherman (dsherman at isisph.com)
 * @author  Brian Sanders (kestrel at burdell dot org) Active Cell support
 * @version 1.0-pre
 */

public class HSSFCell
{

    /**
     * Numeric Cell type (0)
     * @see #setCellType(int)
     * @see #getCellType()
     */

    public final static int          CELL_TYPE_NUMERIC           = 0;

    /**
     * String Cell type (1)
     * @see #setCellType(int)
     * @see #getCellType()
     */

    public final static int          CELL_TYPE_STRING            = 1;

    /**
     * Formula Cell type (2)
     * @see #setCellType(int)
     * @see #getCellType()
     */

    public final static int          CELL_TYPE_FORMULA           = 2;

    /**
     * Blank Cell type (3)
     * @see #setCellType(int)
     * @see #getCellType()
     */

    public final static int          CELL_TYPE_BLANK             = 3;

    /**
     * Boolean Cell type (4)
     * @see #setCellType(int)
     * @see #getCellType()
     */

    public final static int          CELL_TYPE_BOOLEAN           = 4;

    /**
     * Error Cell type (5)
     * @see #setCellType(int)
     * @see #getCellType()
     */

    public final static int          CELL_TYPE_ERROR             = 5;
    public final static short        ENCODING_COMPRESSED_UNICODE = 0;
    public final static short        ENCODING_UTF_16             = 1;
    private short                    cellNum;
    private int                      cellType;
    private HSSFCellStyle            cellStyle;
    private double                   cellValue;
    private String                   stringValue;
    private boolean                  booleanValue;
    private byte                     errorValue;
    private short                    encoding = ENCODING_COMPRESSED_UNICODE;
    private Workbook                 book;
    private Sheet                    sheet;
    //private short                    row;
    private int                    row;
    private CellValueRecordInterface record;

    /**
     * Creates new Cell - Should only be called by HSSFRow.  This creates a cell
     * from scratch.
     * <p>
     * When the cell is initially created it is set to CELL_TYPE_BLANK. Cell types
     * can be changed/overwritten by calling setCellValue with the appropriate
     * type as a parameter although conversions from one type to another may be
     * prohibited.
     *
     * @param book - Workbook record of the workbook containing this cell
     * @param sheet - Sheet record of the sheet containing this cell
     * @param row   - the row of this cell
     * @param col   - the column for this cell
     *
     * @see org.apache.poi.hssf.usermodel.HSSFRow#createCell(short)
     */

    //protected HSSFCell(Workbook book, Sheet sheet, short row, short col)
    protected HSSFCell(Workbook book, Sheet sheet, int row, short col)
    {
        checkBounds(col);
        cellNum      = col;
        this.row     = row;
        cellStyle    = null;
        cellValue    = 0;
        stringValue  = null;
        booleanValue = false;
        errorValue   = ( byte ) 0;
        this.book    = book;
        this.sheet   = sheet;

        // Relying on the fact that by default the cellType is set to 0 which
        // is different to CELL_TYPE_BLANK hence the following method call correctly
        // creates a new blank cell.
        setCellType(CELL_TYPE_BLANK, false);
        ExtendedFormatRecord xf = book.getExFormatAt(0xf);

        setCellStyle(new HSSFCellStyle(( short ) 0xf, xf));
    }

    /**
     * Creates new Cell - Should only be called by HSSFRow.  This creates a cell
     * from scratch.
     *
     * @param book - Workbook record of the workbook containing this cell
     * @param sheet - Sheet record of the sheet containing this cell
     * @param row   - the row of this cell
     * @param col   - the column for this cell
     * @param type  - CELL_TYPE_NUMERIC, CELL_TYPE_STRING, CELL_TYPE_FORMULA, CELL_TYPE_BLANK,
     *                CELL_TYPE_BOOLEAN, CELL_TYPE_ERROR
     *                Type of cell
     * @see org.apache.poi.hssf.usermodel.HSSFRow#createCell(short,int)
     * @deprecated As of 22-Jan-2002 use @see org.apache.poi.hssf.usermodel.HSSFRow#createCell(short)
     * and use setCellValue to specify the type lazily.
     */

    //protected HSSFCell(Workbook book, Sheet sheet, short row, short col,
    protected HSSFCell(Workbook book, Sheet sheet, int row, short col,
                       int type)
    {
        checkBounds(col);
        cellNum      = col;
        this.row     = row;
        cellType     = type;
        cellStyle    = null;
        cellValue    = 0;
        stringValue  = null;
        booleanValue = false;
        errorValue   = ( byte ) 0;
        this.book    = book;
        this.sheet   = sheet;
        switch (type)
        {

            case CELL_TYPE_NUMERIC :
                record = new NumberRecord();
                (( NumberRecord ) record).setColumn(col);
                (( NumberRecord ) record).setRow(row);
                (( NumberRecord ) record).setValue(( short ) 0);
                (( NumberRecord ) record).setXFIndex(( short ) 0);
                break;

            case CELL_TYPE_STRING :
                record = new LabelSSTRecord();
                (( LabelSSTRecord ) record).setColumn(col);
                (( LabelSSTRecord ) record).setRow(row);
                (( LabelSSTRecord ) record).setXFIndex(( short ) 0);
                break;

            case CELL_TYPE_BLANK :
                record = new BlankRecord();
                (( BlankRecord ) record).setColumn(col);
                (( BlankRecord ) record).setRow(row);
                (( BlankRecord ) record).setXFIndex(( short ) 0);
                break;

            case CELL_TYPE_FORMULA :
                FormulaRecord formulaRecord = new FormulaRecord();
                record = new FormulaRecordAggregate(formulaRecord,null);
                formulaRecord.setColumn(col);
                formulaRecord.setRow(row);
                formulaRecord.setXFIndex(( short ) 0);
            case CELL_TYPE_BOOLEAN :
                record = new BoolErrRecord();
                (( BoolErrRecord ) record).setColumn(col);
                (( BoolErrRecord ) record).setRow(row);
                (( BoolErrRecord ) record).setXFIndex(( short ) 0);
                (( BoolErrRecord ) record).setValue(false);
                break;

            case CELL_TYPE_ERROR :
                record = new BoolErrRecord();
                (( BoolErrRecord ) record).setColumn(col);
                (( BoolErrRecord ) record).setRow(row);
                (( BoolErrRecord ) record).setXFIndex(( short ) 0);
                (( BoolErrRecord ) record).setValue(( byte ) 0);
                break;
        }
        ExtendedFormatRecord xf = book.getExFormatAt(0xf);

        setCellStyle(new HSSFCellStyle(( short ) 0xf, xf));
    }

    /**
     * Creates an HSSFCell from a CellValueRecordInterface.  HSSFSheet uses this when
     * reading in cells from an existing sheet.
     *
     * @param book - Workbook record of the workbook containing this cell
     * @param sheet - Sheet record of the sheet containing this cell
     * @param cval - the Cell Value Record we wish to represent
     */

    //protected HSSFCell(Workbook book, Sheet sheet, short row,
    protected HSSFCell(Workbook book, Sheet sheet, int row,
                       CellValueRecordInterface cval)
    {
        cellNum     = cval.getColumn();
        record      = cval;
        this.row    = row;
        cellType    = determineType(cval);
        cellStyle   = null;
        stringValue = null;
        this.book   = book;
        this.sheet  = sheet;
        switch (cellType)
        {

            case CELL_TYPE_NUMERIC :
                cellValue = (( NumberRecord ) cval).getValue();
                break;

            case CELL_TYPE_STRING :
                stringValue =
                    book.getSSTString( ( (LabelSSTRecord ) cval).getSSTIndex());
                break;

            case CELL_TYPE_BLANK :
                break;

            case CELL_TYPE_FORMULA :
                cellValue = (( FormulaRecordAggregate ) cval).getFormulaRecord().getValue();
                stringValue=((FormulaRecordAggregate) cval).getStringValue();
                break;

            case CELL_TYPE_BOOLEAN :
                booleanValue = (( BoolErrRecord ) cval).getBooleanValue();
                break;

            case CELL_TYPE_ERROR :
                errorValue = (( BoolErrRecord ) cval).getErrorValue();
                break;
        }
        ExtendedFormatRecord xf = book.getExFormatAt(cval.getXFIndex());

        setCellStyle(new HSSFCellStyle(( short ) cval.getXFIndex(), xf));
    }

    /**
     * private constructor to prevent blank construction
     */
    private HSSFCell()
    {
    }

    /**
     * used internally -- given a cell value record, figure out its type
     */
    private int determineType(CellValueRecordInterface cval)
    {
        Record record = ( Record ) cval;
        int    sid    = record.getSid();
        int    retval = 0;

        switch (sid)
        {

            case NumberRecord.sid :
                retval = HSSFCell.CELL_TYPE_NUMERIC;
                break;

            case BlankRecord.sid :
                retval = HSSFCell.CELL_TYPE_BLANK;
                break;

            case LabelSSTRecord.sid :
                retval = HSSFCell.CELL_TYPE_STRING;
                break;

            case FormulaRecordAggregate.sid :
                retval = HSSFCell.CELL_TYPE_FORMULA;
                break;

            case BoolErrRecord.sid :
                BoolErrRecord boolErrRecord = ( BoolErrRecord ) record;

                retval = (boolErrRecord.isBoolean())
                         ? HSSFCell.CELL_TYPE_BOOLEAN
                         : HSSFCell.CELL_TYPE_ERROR;
                break;
        }
        return retval;
    }

    /**
     * set the cell's number within the row (0 based)
     * @param num  short the cell number
     */

    public void setCellNum(short num)
    {
        cellNum = num;
        record.setColumn(num);
    }

    /**
     *  get the cell's number within the row
     * @return short reperesenting the column number (logical!)
     */

    public short getCellNum()
    {
        return cellNum;
    }

    /**
     * set the cells type (numeric, formula or string) -- DONT USE FORMULAS IN THIS RELEASE
     * WE'LL THROW YOU A RUNTIME EXCEPTION IF YOU DO
     * @see #CELL_TYPE_NUMERIC
     * @see #CELL_TYPE_STRING
     * @see #CELL_TYPE_FORMULA
     * @see #CELL_TYPE_BLANK
     * @see #CELL_TYPE_BOOLEAN
     * @see #CELL_TYPE_ERROR
     */

    public void setCellType(int cellType)
    {
        setCellType(cellType, true);
    }

    /**
     * sets the cell type. The setValue flag indicates whether to bother about
     *  trying to preserve the current value in the new record if one is created.
     *  <p>
     *  The @see #setCellValue method will call this method with false in setValue
     *  since it will overwrite the cell value later
     *
     */

    private void setCellType(int cellType, boolean setValue)
    {

        // if (cellType == CELL_TYPE_FORMULA)
        // {
        // throw new RuntimeException(
        // "Formulas have not been implemented in this release");
        // }
        if (cellType > CELL_TYPE_ERROR)
        {
            throw new RuntimeException("I have no idea what type that is!");
        }
        switch (cellType)
        {

            case CELL_TYPE_FORMULA :
                FormulaRecordAggregate frec = null;

                if (cellType != this.cellType)
                {
                    frec = new FormulaRecordAggregate(new FormulaRecord(),null);
                }
                else
                {
                    frec = ( FormulaRecordAggregate ) record;
                }
                frec.setColumn(getCellNum());
                if (setValue)
                {
                    frec.getFormulaRecord().setValue(getNumericCellValue());
                }
                frec.setXFIndex(( short ) cellStyle.getIndex());
                frec.setRow(row);
                record = frec;
                break;

            case CELL_TYPE_NUMERIC :
                NumberRecord nrec = null;

                if (cellType != this.cellType)
                {
                    nrec = new NumberRecord();
                }
                else
                {
                    nrec = ( NumberRecord ) record;
                }
                nrec.setColumn(getCellNum());
                if (setValue)
                {
                    nrec.setValue(getNumericCellValue());
                }
                nrec.setXFIndex(( short ) cellStyle.getIndex());
                nrec.setRow(row);
                record = nrec;
                break;

            case CELL_TYPE_STRING :
                LabelSSTRecord lrec = null;

                if (cellType != this.cellType)
                {
                    lrec = new LabelSSTRecord();
                }
                else
                {
                    lrec = ( LabelSSTRecord ) record;
                }
                lrec.setColumn(getCellNum());
                lrec.setRow(row);
                lrec.setXFIndex(( short ) cellStyle.getIndex());
                if (setValue)
                {
                    if ((getStringCellValue() != null)
                            && (!getStringCellValue().equals("")))
                    {
                        int sst = 0;

                        if (encoding == ENCODING_COMPRESSED_UNICODE)
                        {
                            sst = book.addSSTString(getStringCellValue());
                        }
                        if (encoding == ENCODING_UTF_16)
                        {
                            sst = book.addSSTString(getStringCellValue(),
                                                    true);
                        }
                        lrec.setSSTIndex(sst);
                    }
                }
                record = lrec;
                break;

            case CELL_TYPE_BLANK :
                BlankRecord brec = null;

                if (cellType != this.cellType)
                {
                    brec = new BlankRecord();
                }
                else
                {
                    brec = ( BlankRecord ) record;
                }
                brec.setColumn(getCellNum());

                // During construction the cellStyle may be null for a Blank cell.
                if (cellStyle != null)
                {
                    brec.setXFIndex(( short ) cellStyle.getIndex());
                }
                else
                {
                    brec.setXFIndex(( short ) 0);
                }
                brec.setRow(row);
                record = brec;
                break;

            case CELL_TYPE_BOOLEAN :
                BoolErrRecord boolRec = null;

                if (cellType != this.cellType)
                {
                    boolRec = new BoolErrRecord();
                }
                else
                {
                    boolRec = ( BoolErrRecord ) record;
                }
                boolRec.setColumn(getCellNum());
                if (setValue)
                {
                    boolRec.setValue(getBooleanCellValue());
                }
                boolRec.setXFIndex(( short ) cellStyle.getIndex());
                boolRec.setRow(row);
                record = boolRec;
                break;

            case CELL_TYPE_ERROR :
                BoolErrRecord errRec = null;

                if (cellType != this.cellType)
                {
                    errRec = new BoolErrRecord();
                }
                else
                {
                    errRec = ( BoolErrRecord ) record;
                }
                errRec.setColumn(getCellNum());
                if (setValue)
                {
                    errRec.setValue(getErrorCellValue());
                }
                errRec.setXFIndex(( short ) cellStyle.getIndex());
                errRec.setRow(row);
                record = errRec;
                break;
        }
        if (cellType != this.cellType)
        {
            int loc = sheet.getLoc();

            sheet.replaceValueRecord(record);
            sheet.setLoc(loc);
        }
        this.cellType = cellType;
    }

    /**
     * get the cells type (numeric, formula or string)
     * @see #CELL_TYPE_STRING
     * @see #CELL_TYPE_NUMERIC
     * @see #CELL_TYPE_FORMULA
     * @see #CELL_TYPE_BOOLEAN
     * @see #CELL_TYPE_ERROR
     */

    public int getCellType()
    {
        return cellType;
    }

    /**
     * set a numeric value for the cell
     *
     * @param value  the numeric value to set this cell to.  For formulas we'll set the
     *        precalculated value, for numerics we'll set its value. For other types we
     *        will change the cell to a numeric cell and set its value.
     */
    public void setCellValue(double value)
    {
        if ((cellType != CELL_TYPE_NUMERIC) && (cellType != CELL_TYPE_FORMULA))
        {
            setCellType(CELL_TYPE_NUMERIC, false);
        }
        (( NumberRecord ) record).setValue(value);
        cellValue = value;
    }

    /**
     * set a date value for the cell. Excel treats dates as numeric so you will need to format the cell as
     * a date.
     *
     * @param value  the date value to set this cell to.  For formulas we'll set the
     *        precalculated value, for numerics we'll set its value. For other types we
     *        will change the cell to a numeric cell and set its value.
     */
    public void setCellValue(Date value)
    {
        setCellValue(HSSFDateUtil.getExcelDate(value));
    }

    /**
     * set a date value for the cell. Excel treats dates as numeric so you will need to format the cell as
     * a date.
     *
     * @param value  the date value to set this cell to.  For formulas we'll set the
     *        precalculated value, for numerics we'll set its value. For othertypes we
     *        will change the cell to a numeric cell and set its value.
     */
    public void setCellValue(Calendar value)
    {
        setCellValue(value.getTime());
    }

    /**
     * set a string value for the cell. Please note that if you are using
     * full 16 bit unicode you should call <code>setEncoding()</code> first.
     *
     * @param value  value to set the cell to.  For formulas we'll set the formula
     * string, for String cells we'll set its value.  For other types we will
     * change the cell to a string cell and set its value.
     * If value is null then we will change the cell to a Blank cell.
     */

    public void setCellValue(String value)
    {
        if (value == null)
        {
            setCellType(CELL_TYPE_BLANK, false);
        }
        else
        {
            if ((cellType != CELL_TYPE_STRING ) && ( cellType != CELL_TYPE_FORMULA))
            {
                setCellType(CELL_TYPE_STRING, false);
            }
            int index = 0;

            if (encoding == ENCODING_COMPRESSED_UNICODE)
            {
                index = book.addSSTString(value);
            }
            if (encoding == ENCODING_UTF_16)
            {
                index = book.addSSTString(value, true);
            }
            (( LabelSSTRecord ) record).setSSTIndex(index);
            stringValue = value;
        }
    }

    public void setCellFormula(String formula) {
        //Workbook.currentBook=book;
        if (formula==null) {
            setCellType(CELL_TYPE_BLANK,false);
        } else {
            setCellType(CELL_TYPE_FORMULA,false);
            FormulaRecordAggregate rec = (FormulaRecordAggregate) record;
            rec.getFormulaRecord().setOptions(( short ) 2);
            rec.getFormulaRecord().setValue(0);
            
            //only set to default if there is no extended format index already set
            if (rec.getXFIndex() == (short)0) rec.setXFIndex(( short ) 0x0f);
            FormulaParser fp = new FormulaParser(formula+";",book);
            fp.parse();
            Ptg[] ptg  = fp.getRPNPtg();
            int   size = 0;
            //System.out.println("got Ptgs " + ptg.length);
            for (int k = 0; k < ptg.length; k++) {
                size += ptg[ k ].getSize();
                rec.getFormulaRecord().pushExpressionToken(ptg[ k ]);
            }
            rec.getFormulaRecord().setExpressionLength(( short ) size);
            //Workbook.currentBook = null;
        }
    }

    public String getCellFormula() {
        //Workbook.currentBook=book;
        String retval = FormulaParser.toFormulaString(book, ((FormulaRecordAggregate)record).getFormulaRecord().getParsedExpression());
        //Workbook.currentBook=null;
        return retval;
    }


    /**
     * get the value of the cell as a number.  For strings we throw an exception.
     * For blank cells we return a 0.
     */

    public double getNumericCellValue()
    {
        if (cellType == CELL_TYPE_BLANK)
        {
            return 0;
        }
        if (cellType == CELL_TYPE_STRING)
        {
            throw new NumberFormatException(
                "You cannot get a numeric value from a String based cell");
        }
        if (cellType == CELL_TYPE_BOOLEAN)
        {
            throw new NumberFormatException(
                "You cannot get a numeric value from a boolean cell");
        }
        if (cellType == CELL_TYPE_ERROR)
        {
            throw new NumberFormatException(
                "You cannot get a numeric value from an error cell");
        }
        return cellValue;
    }

    /**
     * get the value of the cell as a date.  For strings we throw an exception.
     * For blank cells we return a null.
     */
    public Date getDateCellValue()
    {
        if (cellType == CELL_TYPE_BLANK)
        {
            return null;
        }
        if (cellType == CELL_TYPE_STRING)
        {
            throw new NumberFormatException(
                "You cannot get a date value from a String based cell");
        }
        if (cellType == CELL_TYPE_BOOLEAN)
        {
            throw new NumberFormatException(
                "You cannot get a date value from a boolean cell");
        }
        if (cellType == CELL_TYPE_ERROR)
        {
            throw new NumberFormatException(
                "You cannot get a date value from an error cell");
        }
        if (book.isUsing1904DateWindowing()) {
            return HSSFDateUtil.getJavaDate(cellValue,true);
        }
        else {
            return HSSFDateUtil.getJavaDate(cellValue,false);
        }
    }

    /**
     * get the value of the cell as a string - for numeric cells we throw an exception.
     * For blank cells we return an empty string.
     * For formulaCells that are not string Formulas, we return empty String
     */

    public String getStringCellValue()
    {
        if (cellType == CELL_TYPE_BLANK)
        {
            return "";
        }
        if (cellType == CELL_TYPE_NUMERIC)
        {
            throw new NumberFormatException(
                "You cannot get a string value from a numeric cell");
        }
        if (cellType == CELL_TYPE_BOOLEAN)
        {
            throw new NumberFormatException(
                "You cannot get a string value from a boolean cell");
        }
        if (cellType == CELL_TYPE_ERROR)
        {
            throw new NumberFormatException(
                "You cannot get a string value from an error cell");
        }
        if (cellType == CELL_TYPE_FORMULA) 
        {
            if (stringValue==null) return "";
        }
        return stringValue;
    }

    /**
     * set a boolean value for the cell
     *
     * @param value the boolean value to set this cell to.  For formulas we'll set the
     *        precalculated value, for booleans we'll set its value. For other types we
     *        will change the cell to a boolean cell and set its value.
     */

    public void setCellValue(boolean value)
    {
        if ((cellType != CELL_TYPE_BOOLEAN ) && ( cellType != CELL_TYPE_FORMULA))
        {
            setCellType(CELL_TYPE_BOOLEAN, false);
        }
        (( BoolErrRecord ) record).setValue(value);
        booleanValue = value;
    }

    /**
     * set a error value for the cell
     *
     * @param value the error value to set this cell to.  For formulas we'll set the
     *        precalculated value ??? IS THIS RIGHT??? , for errors we'll set
     *        its value. For other types we will change the cell to an error
     *        cell and set its value.
     */

    public void setCellErrorValue(byte value)
    {
        if ((cellType != CELL_TYPE_ERROR) && (cellType != CELL_TYPE_FORMULA))
        {
            setCellType(CELL_TYPE_ERROR, false);
        }
        (( BoolErrRecord ) record).setValue(value);
        errorValue = value;
    }

    /**
     * get the value of the cell as a boolean.  For strings, numbers, and errors, we throw an exception.
     * For blank cells we return a false.
     */

    public boolean getBooleanCellValue()
    {
        if (cellType == CELL_TYPE_BOOLEAN)
        {
            return booleanValue;
        }
        if (cellType == CELL_TYPE_BLANK)
        {
            return false;
        }
        throw new NumberFormatException(
            "You cannot get a boolean value from a non-boolean cell");
    }

    /**
     * get the value of the cell as an error code.  For strings, numbers, and booleans, we throw an exception.
     * For blank cells we return a 0.
     */

    public byte getErrorCellValue()
    {
        if (cellType == CELL_TYPE_ERROR)
        {
            return errorValue;
        }
        if (cellType == CELL_TYPE_BLANK)
        {
            return ( byte ) 0;
        }
        throw new NumberFormatException(
            "You cannot get an error value from a non-error cell");
    }

    /**
     * set the style for the cell.  The style should be an HSSFCellStyle created/retreived from
     * the HSSFWorkbook.
     *
     * @param style  reference contained in the workbook
     * @see org.apache.poi.hssf.usermodel.HSSFWorkbook#createCellStyle()
     * @see org.apache.poi.hssf.usermodel.HSSFWorkbook#getCellStyleAt(short)
     */

    public void setCellStyle(HSSFCellStyle style)
    {
        cellStyle = style;
        record.setXFIndex(style.getIndex());
    }

    /**
     * get the style for the cell.  This is a reference to a cell style contained in the workbook
     * object.
     * @see org.apache.poi.hssf.usermodel.HSSFWorkbook#getCellStyleAt(short)
     */

    public HSSFCellStyle getCellStyle()
    {
        return cellStyle;
    }

    /**
     * used for internationalization, currently 0 for compressed unicode or 1 for 16-bit
     *
     * @see #ENCODING_COMPRESSED_UNICODE
     * @see #ENCODING_UTF_16
     *
     * @return 1 or 0 for compressed or uncompressed (used only with String type)
     */

    public short getEncoding()
    {
        return encoding;
    }

    /**
     * set the encoding to either 8 or 16 bit. (US/UK use 8-bit, rest of the western world use 16bit)
     *
     * @see #ENCODING_COMPRESSED_UNICODE
     * @see #ENCODING_UTF_16
     *
     * @param encoding either ENCODING_COMPRESSED_UNICODE (0) or ENCODING_UTF_16 (1)
     */

    public void setEncoding(short encoding)
    {
        this.encoding = encoding;
    }

    /**
     * Should only be used by HSSFSheet and friends.  Returns the low level CellValueRecordInterface record
     *
     * @return CellValueRecordInterface representing the cell via the low level api.
     */

    protected CellValueRecordInterface getCellValueRecord()
    {
        return record;
    }

    /**
     * @throws RuntimeException if the bounds are exceeded.
     */
    private void checkBounds(int cellNum) {
      if (cellNum > 255) {
          throw new RuntimeException("You cannot have more than 255 columns "+
                    "in a given row (IV).  Because Excel can't handle it");
      }
      else if (cellNum < 0) {
          throw new RuntimeException("You cannot reference columns with an index of less then 0.");
      }
    }
    
    /**
     * Sets this cell as the active cell for the worksheet
     */
    public void setAsActiveCell()
    {
        this.sheet.setActiveCellRow(this.row);
        this.sheet.setActiveCellCol(this.cellNum);
    }
}