/Classes/PHPExcel/Cell.php

<?php
/**
 * PHPExcel
 *
 * Copyright (c) 2006 - 2012 PHPExcel
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * @category	PHPExcel
 * @package		PHPExcel_Cell
 * @copyright	Copyright (c) 2006 - 2012 PHPExcel (http://www.codeplex.com/PHPExcel)
 * @license		http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt	LGPL
 * @version		1.7.7, 2012-05-19
 */


/**
 * PHPExcel_Cell
 *
 * @category   PHPExcel
 * @package	PHPExcel_Cell
 * @copyright  Copyright (c) 2006 - 2012 PHPExcel (http://www.codeplex.com/PHPExcel)
 */
class PHPExcel_Cell
{
	/**
	 * Value binder to use
	 *
	 * @var PHPExcel_Cell_IValueBinder
	 */
	private static $_valueBinder = null;

	/**
	 * Column of the cell
	 *
	 * @var string
	 */
	private $_column;

	/**
	 * Row of the cell
	 *
	 * @var int
	 */
	private $_row;

	/**
	 * Value of the cell
	 *
	 * @var mixed
	 */
	private $_value;

	/**
	 * Calculated value of the cell (used for caching)
	 *
	 * @var mixed
	 */
	private $_calculatedValue = null;

	/**
	 * Type of the cell data
	 *
	 * @var string
	 */
	private $_dataType;

	/**
	 * Parent worksheet
	 *
	 * @var PHPExcel_Worksheet
	 */
	private $_parent;

	/**
	 * Index to cellXf
	 *
	 * @var int
	 */
	private $_xfIndex;

	/**
	 * Attributes of the formula
	 *
	 *
	 */
	private $_formulaAttributes;


	/**
	 * Send notification to the cache controller
	 *
	 * @return void
	 **/
	public function notifyCacheController() {
		$this->_parent->getCellCacheController()->updateCacheData($this);
		return $this;
	}

	public function detach() {
		$this->_parent = null;
	}

	public function attach($parent) {
		$this->_parent = $parent;
	}


	/**
	 * Create a new Cell
	 *
	 * @param	string				$pColumn
	 * @param	int					$pRow
	 * @param	mixed				$pValue
	 * @param	string				$pDataType
	 * @param	PHPExcel_Worksheet	$pSheet
	 * @throws	Exception
	 */
	public function __construct($pColumn = 'A', $pRow = 1, $pValue = null, $pDataType = null, PHPExcel_Worksheet $pSheet = null)
	{
		// Initialise cell coordinate
		$this->_column = strtoupper($pColumn);
		$this->_row = $pRow;

		// Initialise cell value
		$this->_value = $pValue;

		// Set worksheet
		$this->_parent = $pSheet;

		// Set datatype?
		if ($pDataType !== null) {
			if ($pDataType == PHPExcel_Cell_DataType::TYPE_STRING2)
				$pDataType = PHPExcel_Cell_DataType::TYPE_STRING;
			$this->_dataType = $pDataType;
		} else {
			if (!self::getValueBinder()->bindValue($this, $pValue)) {
				throw new Exception("Value could not be bound to cell.");
			}
		}

		// set default index to cellXf
		$this->_xfIndex = 0;
	}

	/**
	 * Get cell coordinate column
	 *
	 * @return string
	 */
	public function getColumn()
	{
		return $this->_column;
	}

	/**
	 * Get cell coordinate row
	 *
	 * @return int
	 */
	public function getRow()
	{
		return $this->_row;
	}

	/**
	 * Get cell coordinate
	 *
	 * @return string
	 */
	public function getCoordinate()
	{
		return $this->_column . $this->_row;
	}

	/**
	 * Get cell value
	 *
	 * @return mixed
	 */
	public function getValue()
	{
		return $this->_value;
	}

	/**
	 * Get cell value with formatting
	 *
	 * @return string
	 */
	public function getFormattedValue()
	{
		return (string) PHPExcel_Style_NumberFormat::toFormattedString( $this->getCalculatedValue(),
						         $this->_parent->getParent()->getCellXfByIndex($this->getXfIndex())->getNumberFormat()->getFormatCode()
			            );
	}

	/**
	 * Set cell value
	 *
	 * Sets the value for a cell, automatically determining the datatype using the value binder
	 *
	 * @param mixed	$pValue					Value
	 * @return PHPExcel_Cell
	 */
	public function setValue($pValue = null)
	{
		if (!self::getValueBinder()->bindValue($this, $pValue)) {
			throw new Exception("Value could not be bound to cell.");
		}
		return $this;
	}

	/**
	 * Set the value for a cell, with the explicit data type passed to the method (bypassing any use of the value binder)
	 *
	 * @param mixed	$pValue			Value
	 * @param string	$pDataType		Explicit data type
	 * @return PHPExcel_Cell
	 * @throws Exception
	 */
	public function setValueExplicit($pValue = null, $pDataType = PHPExcel_Cell_DataType::TYPE_STRING)
	{
		// set the value according to data type
		switch ($pDataType) {
			case PHPExcel_Cell_DataType::TYPE_STRING2:
				$pDataType = PHPExcel_Cell_DataType::TYPE_STRING;
			case PHPExcel_Cell_DataType::TYPE_STRING:
			case PHPExcel_Cell_DataType::TYPE_NULL:
			case PHPExcel_Cell_DataType::TYPE_INLINE:
				$this->_value = PHPExcel_Cell_DataType::checkString($pValue);
				break;

			case PHPExcel_Cell_DataType::TYPE_NUMERIC:
				$this->_value = (float)$pValue;
				break;

			case PHPExcel_Cell_DataType::TYPE_FORMULA:
				$this->_value = (string)$pValue;
				break;

			case PHPExcel_Cell_DataType::TYPE_BOOL:
				$this->_value = (bool)$pValue;
				break;

			case PHPExcel_Cell_DataType::TYPE_ERROR:
				$this->_value = PHPExcel_Cell_DataType::checkErrorCode($pValue);
				break;

			default:
				throw new Exception('Invalid datatype: ' . $pDataType);
				break;
		}

		// set the datatype
		$this->_dataType = $pDataType;

		return $this->notifyCacheController();
	}

	/**
	 * Get calculated cell value
	 *
	 * @return mixed
	 */
	public function getCalculatedValue($resetLog=true)
	{
//		echo 'Cell '.$this->getCoordinate().' value is a '.$this->_dataType.' with a value of '.$this->getValue().'<br />';
		if ($this->_dataType == PHPExcel_Cell_DataType::TYPE_FORMULA) {
			try {
//				echo 'Cell value for '.$this->getCoordinate().' is a formula: Calculating value<br />';
				$result = PHPExcel_Calculation::getInstance()->calculateCellValue($this,$resetLog);
//				echo $this->getCoordinate().' calculation result is '.$result.'<br />';
			} catch ( Exception $ex ) {
				if (($ex->getMessage() === 'Unable to access External Workbook') && ($this->_calculatedValue !== NULL)) {
//					echo 'Returning fallback value of '.$this->_calculatedValue.' for cell '.$this->getCoordinate().'<br />';
					return $this->_calculatedValue; // Fallback for calculations referencing external files.
				}
//				echo 'Calculation Exception: '.$ex->getMessage().'<br />';
				$result = '#N/A';
				throw(new Exception($this->getParent()->getTitle().'!'.$this->getCoordinate().' -> '.$ex->getMessage()));
			}

			if ($result === '#Not Yet Implemented') {
//				echo 'Returning fallback value of '.$this->_calculatedValue.' for cell '.$this->getCoordinate().'<br />';
				return $this->_calculatedValue; // Fallback if calculation engine does not support the formula.
			}
//			echo 'Returning calculated value of '.$result.' for cell '.$this->getCoordinate().'<br />';
			return $result;
		}

//		if ($this->_value === NULL) {
//			echo 'Cell '.$this->getCoordinate().' has no value, formula or otherwise<br />';
//			return null;
//		}
//		echo 'Cell value for '.$this->getCoordinate().' is not a formula: Returning data value of '.$this->_value.'<br />';
		return $this->_value;
	}

	/**
	 * Set calculated value (used for caching)
	 *
	 * @param mixed $pValue	Value
	 * @return PHPExcel_Cell
	 */
	public function setCalculatedValue($pValue = null)
	{
		if ($pValue !== NULL) {
			$this->_calculatedValue = (is_numeric($pValue)) ? (float) $pValue : $pValue;
		}

		return $this->notifyCacheController();
	}

	/**
	 * Get old calculated value (cached)
	 *
	 * @return mixed
	 */
	public function getOldCalculatedValue()
	{
		return $this->_calculatedValue;
	}

	/**
	 * Get cell data type
	 *
	 * @return string
	 */
	public function getDataType()
	{
		return $this->_dataType;
	}

	/**
	 * Set cell data type
	 *
	 * @param string $pDataType
	 * @return PHPExcel_Cell
	 */
	public function setDataType($pDataType = PHPExcel_Cell_DataType::TYPE_STRING)
	{
		if ($pDataType == PHPExcel_Cell_DataType::TYPE_STRING2)
			$pDataType = PHPExcel_Cell_DataType::TYPE_STRING;

		$this->_dataType = $pDataType;

		return $this->notifyCacheController();
	}

	/**
	 * Has Data validation?
	 *
	 * @return boolean
	 */
	public function hasDataValidation()
	{
		if (!isset($this->_parent)) {
			throw new Exception('Cannot check for data validation when cell is not bound to a worksheet');
		}

		return $this->_parent->dataValidationExists($this->getCoordinate());
	}

	/**
	 * Get Data validation
	 *
	 * @return PHPExcel_Cell_DataValidation
	 */
	public function getDataValidation()
	{
		if (!isset($this->_parent)) {
			throw new Exception('Cannot get data validation for cell that is not bound to a worksheet');
		}

		return $this->_parent->getDataValidation($this->getCoordinate());
	}

	/**
	 * Set Data validation
	 *
	 * @param	PHPExcel_Cell_DataValidation	$pDataValidation
	 * @throws	Exception
	 * @return PHPExcel_Cell
	 */
	public function setDataValidation(PHPExcel_Cell_DataValidation $pDataValidation = null)
	{
		if (!isset($this->_parent)) {
			throw new Exception('Cannot set data validation for cell that is not bound to a worksheet');
		}

		$this->_parent->setDataValidation($this->getCoordinate(), $pDataValidation);

		return $this->notifyCacheController();
	}

	/**
	 * Has Hyperlink
	 *
	 * @return boolean
	 */
	public function hasHyperlink()
	{
		if (!isset($this->_parent)) {
			throw new Exception('Cannot check for hyperlink when cell is not bound to a worksheet');
		}

		return $this->_parent->hyperlinkExists($this->getCoordinate());
	}

	/**
	 * Get Hyperlink
	 *
	 * @throws Exception
	 * @return PHPExcel_Cell_Hyperlink
	 */
	public function getHyperlink()
	{
		if (!isset($this->_parent)) {
			throw new Exception('Cannot get hyperlink for cell that is not bound to a worksheet');
		}

		return $this->_parent->getHyperlink($this->getCoordinate());
	}

	/**
	 * Set Hyperlink
	 *
	 * @param	PHPExcel_Cell_Hyperlink	$pHyperlink
	 * @throws	Exception
	 * @return PHPExcel_Cell
	 */
	public function setHyperlink(PHPExcel_Cell_Hyperlink $pHyperlink = null)
	{
		if (!isset($this->_parent)) {
			throw new Exception('Cannot set hyperlink for cell that is not bound to a worksheet');
		}

		$this->_parent->setHyperlink($this->getCoordinate(), $pHyperlink);

		return $this->notifyCacheController();
	}

	/**
	 * Get parent
	 *
	 * @return PHPExcel_Worksheet
	 */
	public function getParent() {
		return $this->_parent;
	}

	/**
	 * Re-bind parent
	 *
	 * @param PHPExcel_Worksheet $parent
	 * @return PHPExcel_Cell
	 */
	public function rebindParent(PHPExcel_Worksheet $parent) {
		$this->_parent = $parent;

		return $this->notifyCacheController();
	}

	/**
	 * Is cell in a specific range?
	 *
	 * @param	string	$pRange		Cell range (e.g. A1:A1)
	 * @return	boolean
	 */
	public function isInRange($pRange = 'A1:A1')
	{
		list($rangeStart,$rangeEnd) = PHPExcel_Cell::rangeBoundaries($pRange);

		// Translate properties
		$myColumn	= PHPExcel_Cell::columnIndexFromString($this->getColumn());
		$myRow		= $this->getRow();

		// Verify if cell is in range
		return (($rangeStart[0] <= $myColumn) && ($rangeEnd[0] >= $myColumn) &&
				($rangeStart[1] <= $myRow) && ($rangeEnd[1] >= $myRow)
			   );
	}

	/**
	 * Coordinate from string
	 *
	 * @param	string	$pCoordinateString
	 * @return	array	Array containing column and row (indexes 0 and 1)
	 * @throws	Exception
	 */
	public static function coordinateFromString($pCoordinateString = 'A1')
	{
		if (preg_match("/^([$]?[A-Z]{1,3})([$]?\d{1,7})$/", $pCoordinateString, $matches)) {
			return array($matches[1],$matches[2]);
		} elseif ((strpos($pCoordinateString,':') !== false) || (strpos($pCoordinateString,',') !== false)) {
			throw new Exception('Cell coordinate string can not be a range of cells.');
		} elseif ($pCoordinateString == '') {
			throw new Exception('Cell coordinate can not be zero-length string.');
		} else {
			throw new Exception('Invalid cell coordinate '.$pCoordinateString);
		}
	}

	/**
	 * Make string row, column or cell coordinate absolute
	 *
	 * @param	string	$pCoordinateString		e.g. 'A' or '1' or 'A1'
	 * @return	string	Absolute coordinate		e.g. '$A' or '$1' or '$A$1'
	 * @throws	Exception
	 */
	public static function absoluteReference($pCoordinateString = 'A1')
	{
		if (strpos($pCoordinateString,':') === false && strpos($pCoordinateString,',') === false) {
			// Create absolute coordinate
			if (ctype_digit($pCoordinateString)) {
				return '$'.$pCoordinateString;
			} elseif (ctype_alpha($pCoordinateString)) {
				return '$'.strtoupper($pCoordinateString);
			}
			return self::absoluteCoordinate($pCoordinateString);
		} else {
			throw new Exception("Coordinate string should not be a cell range.");
		}
	}

	/**
	 * Make string coordinate absolute
	 *
	 * @param	string	$pCoordinateString		e.g. 'A1'
	 * @return	string	Absolute coordinate		e.g. '$A$1'
	 * @throws	Exception
	 */
	public static function absoluteCoordinate($pCoordinateString = 'A1')
	{
		if (strpos($pCoordinateString,':') === false && strpos($pCoordinateString,',') === false) {
			// Create absolute coordinate
			$worksheet = '';
			$cellAddress = explode('!',$pCoordinateString);
			if (count($cellAddress) == 2) {
				list($worksheet,$pCoordinateString) = $cellAddress;
			}

			list($column, $row) = PHPExcel_Cell::coordinateFromString($pCoordinateString);
			if ($column[0] == '$')	$column = substr($column,1);
			if ($row[0] == '$')		$row = substr($row,1);
			if ($worksheet > '')
				$worksheet .= '!';
			return $worksheet . '$' . $column . '$' . $row;
		} else {
			throw new Exception("Coordinate string should not be a cell range.");
		}
	}

	/**
	 * Split range into coordinate strings
	 *
	 * @param	string	$pRange
	 * @return	array	Array containg one or more arrays containing one or two coordinate strings
	 */
	public static function splitRange($pRange = 'A1:A1')
	{
		$exploded = explode(',', $pRange);
		$counter = count($exploded);
		for ($i = 0; $i < $counter; ++$i) {
			$exploded[$i] = explode(':', $exploded[$i]);
		}
		return $exploded;
	}

	/**
	 * Build range from coordinate strings
	 *
	 * @param	array	$pRange	Array containg one or more arrays containing one or two coordinate strings
	 * @return  string	String representation of $pRange
	 * @throws	Exception
	 */
	public static function buildRange($pRange)
	{
		// Verify range
		if (!is_array($pRange) || empty($pRange) || !is_array($pRange[0])) {
			throw new Exception('Range does not contain any information.');
		}

		// Build range
		$imploded = array();
		$counter = count($pRange);
		for ($i = 0; $i < $counter; ++$i) {
			$pRange[$i] = implode(':', $pRange[$i]);
		}
		$imploded = implode(',', $pRange);

		return $imploded;
	}

	/**
	 * Calculate range boundaries
	 *
	 * @param	string	$pRange		Cell range (e.g. A1:A1)
	 * @return	array	Range coordinates (Start Cell, End Cell) where Start Cell and End Cell are arrays (Column Number, Row Number)
	 */
	public static function rangeBoundaries($pRange = 'A1:A1')
	{
		// Uppercase coordinate
		$pRange = strtoupper($pRange);

		// Extract range
		if (strpos($pRange, ':') === false) {
			$rangeA = $rangeB = $pRange;
		} else {
			list($rangeA, $rangeB) = explode(':', $pRange);
		}

		// Calculate range outer borders
		$rangeStart = PHPExcel_Cell::coordinateFromString($rangeA);
		$rangeEnd	= PHPExcel_Cell::coordinateFromString($rangeB);

		// Translate column into index
		$rangeStart[0]	= PHPExcel_Cell::columnIndexFromString($rangeStart[0]);
		$rangeEnd[0]	= PHPExcel_Cell::columnIndexFromString($rangeEnd[0]);

		return array($rangeStart, $rangeEnd);
	}

	/**
	 * Calculate range dimension
	 *
	 * @param	string	$pRange		Cell range (e.g. A1:A1)
	 * @return	array	Range dimension (width, height)
	 */
	public static function rangeDimension($pRange = 'A1:A1')
	{
		// Calculate range outer borders
		list($rangeStart,$rangeEnd) = PHPExcel_Cell::rangeBoundaries($pRange);

		return array( ($rangeEnd[0] - $rangeStart[0] + 1), ($rangeEnd[1] - $rangeStart[1] + 1) );
	}

	/**
	 * Calculate range boundaries
	 *
	 * @param	string	$pRange		Cell range (e.g. A1:A1)
	 * @return	array	Range boundaries (staring Column, starting Row, Final Column, Final Row)
	 */
	public static function getRangeBoundaries($pRange = 'A1:A1')
	{
		// Uppercase coordinate
		$pRange = strtoupper($pRange);

		// Extract range
		if (strpos($pRange, ':') === false) {
			$rangeA = $rangeB = $pRange;
		} else {
			list($rangeA, $rangeB) = explode(':', $pRange);
		}

		return array( self::coordinateFromString($rangeA), self::coordinateFromString($rangeB));
	}

	/**
	 * Column index from string
	 *
	 * @param	string $pString
	 * @return	int Column index (base 1 !!!)
	 * @throws	Exception
	 */
	public static function columnIndexFromString($pString = 'A')
	{
		//	Using a lookup cache adds a slight memory overhead, but boosts speed
		//	caching using a static within the method is faster than a class static,
		//		though it's additional memory overhead
		static $_indexCache = array();

		if (isset($_indexCache[$pString]))
			return $_indexCache[$pString];

		//	It's surprising how costly the strtoupper() and ord() calls actually are, so we use a lookup array rather than use ord()
		//		and make it case insensitive to get rid of the strtoupper() as well. Because it's a static, there's no significant
		//		memory overhead either
		static $_columnLookup = array(
			'A' => 1, 'B' => 2, 'C' => 3, 'D' => 4, 'E' => 5, 'F' => 6, 'G' => 7, 'H' => 8, 'I' => 9, 'J' => 10, 'K' => 11, 'L' => 12, 'M' => 13,
			'N' => 14, 'O' => 15, 'P' => 16, 'Q' => 17, 'R' => 18, 'S' => 19, 'T' => 20, 'U' => 21, 'V' => 22, 'W' => 23, 'X' => 24, 'Y' => 25, 'Z' => 26,
			'a' => 1, 'b' => 2, 'c' => 3, 'd' => 4, 'e' => 5, 'f' => 6, 'g' => 7, 'h' => 8, 'i' => 9, 'j' => 10, 'k' => 11, 'l' => 12, 'm' => 13,
			'n' => 14, 'o' => 15, 'p' => 16, 'q' => 17, 'r' => 18, 's' => 19, 't' => 20, 'u' => 21, 'v' => 22, 'w' => 23, 'x' => 24, 'y' => 25, 'z' => 26
		);

		//	We also use the language construct isset() rather than the more costly strlen() function to match the length of $pString
		//		for improved performance
		if (isset($pString{0})) {
			if (!isset($pString{1})) {
				$_indexCache[$pString] = $_columnLookup[$pString];
				return $_indexCache[$pString];
			} elseif(!isset($pString{2})) {
				$_indexCache[$pString] = $_columnLookup[$pString{0}] * 26 + $_columnLookup[$pString{1}];
				return $_indexCache[$pString];
			} elseif(!isset($pString{3})) {
				$_indexCache[$pString] = $_columnLookup[$pString{0}] * 676 + $_columnLookup[$pString{1}] * 26 + $_columnLookup[$pString{2}];
				return $_indexCache[$pString];
			}
		}
		throw new Exception("Column string index can not be " . ((isset($pString{0})) ? "longer than 3 characters" : "empty") . ".");
	}

	/**
	 * String from columnindex
	 *
	 * @param int $pColumnIndex Column index (base 0 !!!)
	 * @return string
	 */
	public static function stringFromColumnIndex($pColumnIndex = 0)
	{
		//	Using a lookup cache adds a slight memory overhead, but boosts speed
		//	caching using a static within the method is faster than a class static,
		//		though it's additional memory overhead
		static $_indexCache = array();

		if (!isset($_indexCache[$pColumnIndex])) {
			// Determine column string
			if ($pColumnIndex < 26) {
				$_indexCache[$pColumnIndex] = chr(65 + $pColumnIndex);
			} elseif ($pColumnIndex < 702) {
				$_indexCache[$pColumnIndex] = chr(64 + ($pColumnIndex / 26)) .
											  chr(65 + $pColumnIndex % 26);
			} else {
				$_indexCache[$pColumnIndex] = chr(64 + (($pColumnIndex - 26) / 676)) .
											  chr(65 + ((($pColumnIndex - 26) % 676) / 26)) .
											  chr(65 + $pColumnIndex % 26);
			}
		}
		return $_indexCache[$pColumnIndex];
	}

	/**
	 * Extract all cell references in range
	 *
	 * @param	string	$pRange		Range (e.g. A1 or A1:A10 or A1:A10 A100:A1000)
	 * @return	array	Array containing single cell references
	 */
	public static function extractAllCellReferencesInRange($pRange = 'A1') {
		// Returnvalue
		$returnValue = array();

		// Explode spaces
		$cellBlocks = explode(' ', str_replace('$', '', strtoupper($pRange)));
		foreach ($cellBlocks as $cellBlock) {
			// Single cell?
			if (strpos($cellBlock,':') === false && strpos($cellBlock,',') === false) {
				$returnValue[] = $cellBlock;
				continue;
			}

			// Range...
			$ranges = PHPExcel_Cell::splitRange($cellBlock);
			foreach($ranges as $range) {
				// Single cell?
				if (!isset($range[1])) {
					$returnValue[] = $range[0];
					continue;
				}

				// Range...
				list($rangeStart, $rangeEnd)	= $range;
				list($startCol, $startRow)	= sscanf($rangeStart,'%[A-Z]%d');
				list($endCol, $endRow)		= sscanf($rangeEnd,'%[A-Z]%d');
				$endCol++;

				// Current data
				$currentCol	= $startCol;
				$currentRow	= $startRow;

				// Loop cells
				while ($currentCol != $endCol) {
					while ($currentRow <= $endRow) {
						$returnValue[] = $currentCol.$currentRow;
						++$currentRow;
					}
					++$currentCol;
					$currentRow = $startRow;
				}
			}
		}

		// Return value
		return $returnValue;
	}

	/**
	 * Compare 2 cells
	 *
	 * @param	PHPExcel_Cell	$a	Cell a
	 * @param	PHPExcel_Cell	$a	Cell b
	 * @return	int		Result of comparison (always -1 or 1, never zero!)
	 */
	public static function compareCells(PHPExcel_Cell $a, PHPExcel_Cell $b)
	{
		if ($a->_row < $b->_row) {
			return -1;
		} elseif ($a->_row > $b->_row) {
			return 1;
		} elseif (PHPExcel_Cell::columnIndexFromString($a->_column) < PHPExcel_Cell::columnIndexFromString($b->_column)) {
			return -1;
		} else {
			return 1;
		}
	}

	/**
	 * Get value binder to use
	 *
	 * @return PHPExcel_Cell_IValueBinder
	 */
	public static function getValueBinder() {
		if (self::$_valueBinder === NULL) {
			self::$_valueBinder = new PHPExcel_Cell_DefaultValueBinder();
		}

		return self::$_valueBinder;
	}

	/**
	 * Set value binder to use
	 *
	 * @param PHPExcel_Cell_IValueBinder $binder
	 * @throws Exception
	 */
	public static function setValueBinder(PHPExcel_Cell_IValueBinder $binder = null) {
		if ($binder === NULL) {
			throw new Exception("A PHPExcel_Cell_IValueBinder is required for PHPExcel to function correctly.");
		}

		self::$_valueBinder = $binder;
	}

	/**
	 * Implement PHP __clone to create a deep clone, not just a shallow copy.
	 */
	public function __clone() {
		$vars = get_object_vars($this);
		foreach ($vars as $key => $value) {
			if ((is_object($value)) && ($key != '_parent')) {
				$this->$key = clone $value;
			} else {
				$this->$key = $value;
			}
		}
	}

	/**
	 * Get index to cellXf
	 *
	 * @return int
	 */
	public function getXfIndex()
	{
		return $this->_xfIndex;
	}

	/**
	 * Set index to cellXf
	 *
	 * @param int $pValue
	 * @return PHPExcel_Cell
	 */
	public function setXfIndex($pValue = 0)
	{
		$this->_xfIndex = $pValue;

		return $this->notifyCacheController();
	}


	public function setFormulaAttributes($pAttributes)
	{
		$this->_formulaAttributes = $pAttributes;
		return $this;
	}

	public function getFormulaAttributes()
	{
		return $this->_formulaAttributes;
	}

}