/**
* Write a formula to the specified row and column (zero indexed).
* The textual representation of the formula is passed to the parser in
* Parser.php which returns a packed binary string.
*
* Returns 0 : normal termination
* -1 : formula errors (bad formula)
* -2 : row or column out of range
*
* @access public
* @param integer $row Zero indexed row
* @param integer $col Zero indexed column
* @param string $formula The formula text string
* @param mixed $format The optional XF format
* @return integer
*/
public function writeFormula($row, $col, $formula, $format = null)
{
$record = 0x6;
// Record identifier
// Excel normally stores the last calculated value of the formula in $num.
// Clearly we are not in a position to calculate this a priori. Instead
// we set $num to zero and set the option flags in $grbit to ensure
// automatic calculation of the formula when the file is opened.
//
$xf = $this->_XF($format);
// The cell format
$num = 0x0;
// Current value of formula
$grbit = 0x3;
// Option flags
$unknown = 0x0;
// Must be zero
// Check that row and col are valid and store max and min values
if ($this->_checkRowCol($row, $col) == false) {
return -2;
}
// Strip the '=' or '@' sign at the beginning of the formula string
if (preg_match("/^=/", $formula)) {
$formula = preg_replace("/(^=)/", "", $formula);
} elseif (preg_match("/^@/", $formula)) {
$formula = preg_replace("/(^@)/", "", $formula);
} else {
// Error handling
$this->writeString($row, $col, 'Unrecognised character for formula');
return -1;
}
// Parse the formula using the parser in Parser.php
$error = $this->_parser->parse($formula);
if ($this->isError($error)) {
$this->writeString($row, $col, $error->getMessage());
return -1;
}
$formula = $this->_parser->toReversePolish();
if ($this->isError($formula)) {
$this->writeString($row, $col, $formula->getMessage());
return -1;
}
$formlen = strlen($formula);
// Length of the binary string
$length = 0x16 + $formlen;
// Length of the record data
$header = pack("vv", $record, $length);
$data = pack("vvvdvVv", $row, $col, $xf, $num, $grbit, $unknown, $formlen);
$this->_append($header . $data . $formula);
return 0;
}
