FormulaParser.php

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<?php
/*
PARTLY BASED ON:
        Copyright (c) 2007 E. W. Bachtal, Inc.
 
        Permission is hereby granted, free of charge, to any person obtaining a copy of this software
        and associated documentation files (the "Software"), to deal in the Software without restriction,
        including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
        and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so,
        subject to the following conditions:
 
          The above copyright notice and this permission notice shall be included in all copies or substantial
          portions of the Software.
 
        The software is provided "as is", without warranty of any kind, express or implied, including but not
        limited to the warranties of merchantability, fitness for a particular purpose and noninfringement. In
        no event shall the authors or copyright holders be liable for any claim, damages or other liability,
        whether in an action of contract, tort or otherwise, arising from, out of or in connection with the
        software or the use or other dealings in the software.
 
        http://ewbi.blogs.com/develops/2007/03/excel_formula_p.html
        http://ewbi.blogs.com/develops/2004/12/excel_formula_p.html
*/
 
class PHPExcel_Calculation_FormulaParser {
        /* Character constants */
        const QUOTE_DOUBLE  = '"';
        const QUOTE_SINGLE  = '\'';
        const BRACKET_CLOSE = ']';
        const BRACKET_OPEN  = '[';
        const BRACE_OPEN    = '{';
        const BRACE_CLOSE   = '}';
        const PAREN_OPEN    = '(';
        const PAREN_CLOSE   = ')';
        const SEMICOLON     = ';';
        const WHITESPACE    = ' ';
        const COMMA         = ',';
        const ERROR_START   = '#';
 
        const OPERATORS_SN                      = "+-";
        const OPERATORS_INFIX           = "+-*/^&=><";
        const OPERATORS_POSTFIX         = "%";
 
        private $_formula;
 
        private $_tokens = array();
 
    public function __construct($pFormula = '')
    {
        // Check parameters
        if (is_null($pFormula)) {
                throw new PHPExcel_Calculation_Exception("Invalid parameter passed: formula");
        }
 
        // Initialise values
        $this->_formula = trim($pFormula);
        // Parse!
        $this->_parseToTokens();
    }
 
    public function getFormula() {
        return $this->_formula;
    }
 
    public function getToken($pId = 0) {
        if (isset($this->_tokens[$pId])) {
                return $this->_tokens[$pId];
        } else {
                throw new PHPExcel_Calculation_Exception("Token with id $pId does not exist.");
        }
    }
 
    public function getTokenCount() {
        return count($this->_tokens);
    }
 
    public function getTokens() {
        return $this->_tokens;
    }
 
    private function _parseToTokens() {
                // No attempt is made to verify formulas; assumes formulas are derived from Excel, where
                // they can only exist if valid; stack overflows/underflows sunk as nulls without exceptions.
 
                // Check if the formula has a valid starting =
                $formulaLength = strlen($this->_formula);
                if ($formulaLength < 2 || $this->_formula{0} != '=') return;
 
                // Helper variables
                $tokens1        = $tokens2      = $stack = array();
                $inString       = $inPath       = $inRange      = $inError = false;
                $token          = $previousToken        = $nextToken    = null;
 
                $index  = 1;
                $value  = '';
 
                $ERRORS                         = array("#NULL!", "#DIV/0!", "#VALUE!", "#REF!", "#NAME?", "#NUM!", "#N/A");
                $COMPARATORS_MULTI      = array(">=", "<=", "<>");
 
                while ($index < $formulaLength) {
                        // state-dependent character evaluation (order is important)
 
                        // double-quoted strings
                        // embeds are doubled
                        // end marks token
                        if ($inString) {
                                if ($this->_formula{$index} == PHPExcel_Calculation_FormulaParser::QUOTE_DOUBLE) {
                                        if ((($index + 2) <= $formulaLength) && ($this->_formula{$index + 1} == PHPExcel_Calculation_FormulaParser::QUOTE_DOUBLE)) {
                                                $value .= PHPExcel_Calculation_FormulaParser::QUOTE_DOUBLE;
                                                ++$index;
                                        } else {
                                                $inString = false;
                                                $tokens1[] = new PHPExcel_Calculation_FormulaToken($value, PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERAND, PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_TEXT);
                                                $value = "";
                                        }
                                } else {
                                        $value .= $this->_formula{$index};
                                }
                                ++$index;
                                continue;
                        }
 
                        // single-quoted strings (links)
                        // embeds are double
                        // end does not mark a token
                        if ($inPath) {
                                if ($this->_formula{$index} == PHPExcel_Calculation_FormulaParser::QUOTE_SINGLE) {
                                        if ((($index + 2) <= $formulaLength) && ($this->_formula{$index + 1} == PHPExcel_Calculation_FormulaParser::QUOTE_SINGLE)) {
                                                $value .= PHPExcel_Calculation_FormulaParser::QUOTE_SINGLE;
                                                ++$index;
                                        } else {
                                                $inPath = false;
                                        }
                                } else {
                                        $value .= $this->_formula{$index};
                                }
                                ++$index;
                                continue;
                        }
 
                        // bracked strings (R1C1 range index or linked workbook name)
                        // no embeds (changed to "()" by Excel)
                        // end does not mark a token
                        if ($inRange) {
                                if ($this->_formula{$index} == PHPExcel_Calculation_FormulaParser::BRACKET_CLOSE) {
                                        $inRange = false;
                                }
                                $value .= $this->_formula{$index};
                                ++$index;
                                continue;
                        }
 
                        // error values
                        // end marks a token, determined from absolute list of values
                        if ($inError) {
                                $value .= $this->_formula{$index};
                                ++$index;
                                if (in_array($value, $ERRORS)) {
                                        $inError = false;
                                        $tokens1[] = new PHPExcel_Calculation_FormulaToken($value, PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERAND, PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_ERROR);
                                        $value = "";
                                }
                                continue;
                        }
 
                        // scientific notation check
                        if (strpos(PHPExcel_Calculation_FormulaParser::OPERATORS_SN, $this->_formula{$index}) !== false) {
                                if (strlen($value) > 1) {
                                        if (preg_match("/^[1-9]{1}(\.[0-9]+)?E{1}$/", $this->_formula{$index}) != 0) {
                                                $value .= $this->_formula{$index};
                                                ++$index;
                                                continue;
                                        }
                                }
                        }
 
                        // independent character evaluation (order not important)
 
                        // establish state-dependent character evaluations
                        if ($this->_formula{$index} == PHPExcel_Calculation_FormulaParser::QUOTE_DOUBLE) {
                                if (strlen($value > 0)) {  // unexpected
                                        $tokens1[] = new PHPExcel_Calculation_FormulaToken($value, PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_UNKNOWN);
                                        $value = "";
                                }
                                $inString = true;
                                ++$index;
                                continue;
                        }
 
                        if ($this->_formula{$index} == PHPExcel_Calculation_FormulaParser::QUOTE_SINGLE) {
                                if (strlen($value) > 0) { // unexpected
                                        $tokens1[] = new PHPExcel_Calculation_FormulaToken($value, PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_UNKNOWN);
                                        $value = "";
                                }
                                $inPath = true;
                                ++$index;
                                continue;
                        }
 
                        if ($this->_formula{$index} == PHPExcel_Calculation_FormulaParser::BRACKET_OPEN) {
                                $inRange = true;
                                $value .= PHPExcel_Calculation_FormulaParser::BRACKET_OPEN;
                                ++$index;
                                continue;
                        }
 
                        if ($this->_formula{$index} == PHPExcel_Calculation_FormulaParser::ERROR_START) {
                                if (strlen($value) > 0) { // unexpected
                                        $tokens1[] = new PHPExcel_Calculation_FormulaToken($value, PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_UNKNOWN);
                                        $value = "";
                                }
                                $inError = true;
                                $value .= PHPExcel_Calculation_FormulaParser::ERROR_START;
                                ++$index;
                                continue;
                        }
 
                        // mark start and end of arrays and array rows
                        if ($this->_formula{$index} == PHPExcel_Calculation_FormulaParser::BRACE_OPEN) {
                                if (strlen($value) > 0) { // unexpected
                                        $tokens1[] = new PHPExcel_Calculation_FormulaToken($value, PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_UNKNOWN);
                                        $value = "";
                                }
 
                                $tmp = new PHPExcel_Calculation_FormulaToken("ARRAY", PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_FUNCTION, PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_START);
                                $tokens1[] = $tmp;
                                $stack[] = clone $tmp;
 
                                $tmp = new PHPExcel_Calculation_FormulaToken("ARRAYROW", PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_FUNCTION, PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_START);
                                $tokens1[] = $tmp;
                                $stack[] = clone $tmp;
 
                                ++$index;
                                continue;
                        }
 
                        if ($this->_formula{$index} == PHPExcel_Calculation_FormulaParser::SEMICOLON) {
                                if (strlen($value) > 0) {
                                        $tokens1[] = new PHPExcel_Calculation_FormulaToken($value, PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERAND);
                                        $value = "";
                                }
 
                                $tmp = array_pop($stack);
                                $tmp->setValue("");
                                $tmp->setTokenSubType(PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_STOP);
                                $tokens1[] = $tmp;
 
                                $tmp = new PHPExcel_Calculation_FormulaToken(",", PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_ARGUMENT);
                                $tokens1[] = $tmp;
 
                                $tmp = new PHPExcel_Calculation_FormulaToken("ARRAYROW", PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_FUNCTION, PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_START);
                                $tokens1[] = $tmp;
                                $stack[] = clone $tmp;
 
                                ++$index;
                                continue;
                        }
 
                        if ($this->_formula{$index} == PHPExcel_Calculation_FormulaParser::BRACE_CLOSE) {
                                if (strlen($value) > 0) {
                                        $tokens1[] = new PHPExcel_Calculation_FormulaToken($value, PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERAND);
                                        $value = "";
                                }
 
                                $tmp = array_pop($stack);
                                $tmp->setValue("");
                                $tmp->setTokenSubType(PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_STOP);
                                $tokens1[] = $tmp;
 
                                $tmp = array_pop($stack);
                                $tmp->setValue("");
                                $tmp->setTokenSubType(PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_STOP);
                                $tokens1[] = $tmp;
 
                                ++$index;
                                continue;
                        }
 
                        // trim white-space
                        if ($this->_formula{$index} == PHPExcel_Calculation_FormulaParser::WHITESPACE) {
                                if (strlen($value) > 0) {
                                        $tokens1[] = new PHPExcel_Calculation_FormulaToken($value, PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERAND);
                                        $value = "";
                                }
                                $tokens1[] = new PHPExcel_Calculation_FormulaToken("", PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_WHITESPACE);
                                ++$index;
                                while (($this->_formula{$index} == PHPExcel_Calculation_FormulaParser::WHITESPACE) && ($index < $formulaLength)) {
                                        ++$index;
                                }
                                continue;
                        }
 
                        // multi-character comparators
                        if (($index + 2) <= $formulaLength) {
                                if (in_array(substr($this->_formula, $index, 2), $COMPARATORS_MULTI)) {
                                        if (strlen($value) > 0) {
                                                $tokens1[] = new PHPExcel_Calculation_FormulaToken($value, PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERAND);
                                                $value = "";
                                        }
                                        $tokens1[] = new PHPExcel_Calculation_FormulaToken(substr($this->_formula, $index, 2), PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERATORINFIX, PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_LOGICAL);
                                        $index += 2;
                                        continue;
                                }
                        }
 
                        // standard infix operators
                        if (strpos(PHPExcel_Calculation_FormulaParser::OPERATORS_INFIX, $this->_formula{$index}) !== false) {
                                if (strlen($value) > 0) {
                                        $tokens1[] =new PHPExcel_Calculation_FormulaToken($value, PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERAND);
                                        $value = "";
                                }
                                $tokens1[] = new PHPExcel_Calculation_FormulaToken($this->_formula{$index}, PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERATORINFIX);
                                ++$index;
                                continue;
                        }
 
                        // standard postfix operators (only one)
                        if (strpos(PHPExcel_Calculation_FormulaParser::OPERATORS_POSTFIX, $this->_formula{$index}) !== false) {
                                if (strlen($value) > 0) {
                                        $tokens1[] = new PHPExcel_Calculation_FormulaToken($value, PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERAND);
                                        $value = "";
                                }
                                $tokens1[] = new PHPExcel_Calculation_FormulaToken($this->_formula{$index}, PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERATORPOSTFIX);
                                ++$index;
                                continue;
                        }
 
                        // start subexpression or function
                        if ($this->_formula{$index} == PHPExcel_Calculation_FormulaParser::PAREN_OPEN) {
                                if (strlen($value) > 0) {
                                        $tmp = new PHPExcel_Calculation_FormulaToken($value, PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_FUNCTION, PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_START);
                                        $tokens1[] = $tmp;
                                        $stack[] = clone $tmp;
                                        $value = "";
                                } else {
                                        $tmp = new PHPExcel_Calculation_FormulaToken("", PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_SUBEXPRESSION, PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_START);
                                        $tokens1[] = $tmp;
                                        $stack[] = clone $tmp;
                                }
                                ++$index;
                                continue;
                        }
 
                        // function, subexpression, or array parameters, or operand unions
                        if ($this->_formula{$index} == PHPExcel_Calculation_FormulaParser::COMMA) {
                                if (strlen($value) > 0) {
                                        $tokens1[] = new PHPExcel_Calculation_FormulaToken($value, PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERAND);
                                        $value = "";
                                }
 
                                $tmp = array_pop($stack);
                                $tmp->setValue("");
                                $tmp->setTokenSubType(PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_STOP);
                                $stack[] = $tmp;
 
                                if ($tmp->getTokenType() == PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_FUNCTION) {
                                        $tokens1[] = new PHPExcel_Calculation_FormulaToken(",", PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERATORINFIX, PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_UNION);
                                } else {
                                        $tokens1[] = new PHPExcel_Calculation_FormulaToken(",", PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_ARGUMENT);
                                }
                                ++$index;
                                continue;
                        }
 
                        // stop subexpression
                        if ($this->_formula{$index} == PHPExcel_Calculation_FormulaParser::PAREN_CLOSE) {
                                if (strlen($value) > 0) {
                                        $tokens1[] = new PHPExcel_Calculation_FormulaToken($value, PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERAND);
                                        $value = "";
                                }
 
                                $tmp = array_pop($stack);
                                $tmp->setValue("");
                                $tmp->setTokenSubType(PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_STOP);
                                $tokens1[] = $tmp;
 
                                ++$index;
                                continue;
                        }
 
                // token accumulation
                        $value .= $this->_formula{$index};
                        ++$index;
                }
 
                // dump remaining accumulation
                if (strlen($value) > 0) {
                        $tokens1[] = new PHPExcel_Calculation_FormulaToken($value, PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERAND);
                }
 
                // move tokenList to new set, excluding unnecessary white-space tokens and converting necessary ones to intersections
                $tokenCount = count($tokens1);
                for ($i = 0; $i < $tokenCount; ++$i) {
                        $token = $tokens1[$i];
                        if (isset($tokens1[$i - 1])) {
                                $previousToken = $tokens1[$i - 1];
                        } else {
                                $previousToken = null;
                        }
                        if (isset($tokens1[$i + 1])) {
                                $nextToken = $tokens1[$i + 1];
                        } else {
                                $nextToken = null;
                        }
 
                        if (is_null($token)) {
                                continue;
                        }
 
                        if ($token->getTokenType() != PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_WHITESPACE) {
                                $tokens2[] = $token;
                                continue;
                        }
 
                        if (is_null($previousToken)) {
                                continue;
                        }
 
                        if (! (
                                        (($previousToken->getTokenType() == PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_FUNCTION) && ($previousToken->getTokenSubType() == PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_STOP)) ||
                                        (($previousToken->getTokenType() == PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_SUBEXPRESSION) && ($previousToken->getTokenSubType() == PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_STOP)) ||
                                        ($previousToken->getTokenType() == PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERAND)
                                  ) ) {
                                continue;
                        }
 
                        if (is_null($nextToken)) {
                                continue;
                        }
 
                        if (! (
                                        (($nextToken->getTokenType() == PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_FUNCTION) && ($nextToken->getTokenSubType() == PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_START)) ||
                                        (($nextToken->getTokenType() == PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_SUBEXPRESSION) && ($nextToken->getTokenSubType() == PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_START)) ||
                                        ($nextToken->getTokenType() == PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERAND)
                                  ) ) {
                                continue;
                        }
 
                        $tokens2[] = new PHPExcel_Calculation_FormulaToken($value, PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERATORINFIX, PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_INTERSECTION);
                }
 
                // move tokens to final list, switching infix "-" operators to prefix when appropriate, switching infix "+" operators
                // to noop when appropriate, identifying operand and infix-operator subtypes, and pulling "@" from function names
                $this->_tokens = array();
 
                $tokenCount = count($tokens2);
                for ($i = 0; $i < $tokenCount; ++$i) {
                        $token = $tokens2[$i];
                        if (isset($tokens2[$i - 1])) {
                                $previousToken = $tokens2[$i - 1];
                        } else {
                                $previousToken = null;
                        }
                        if (isset($tokens2[$i + 1])) {
                                $nextToken = $tokens2[$i + 1];
                        } else {
                                $nextToken = null;
                        }
 
                        if (is_null($token)) {
                                continue;
                        }
 
                        if ($token->getTokenType() == PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERATORINFIX && $token->getValue() == "-") {
                                if ($i == 0) {
                                        $token->setTokenType(PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERATORPREFIX);
                                } else if (
                                                        (($previousToken->getTokenType() == PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_FUNCTION) && ($previousToken->getTokenSubType() == PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_STOP)) ||
                                                        (($previousToken->getTokenType() == PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_SUBEXPRESSION) && ($previousToken->getTokenSubType() == PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_STOP)) ||
                                                        ($previousToken->getTokenType() == PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERATORPOSTFIX) ||
                                                        ($previousToken->getTokenType() == PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERAND)
                                                ) {
                                        $token->setTokenSubType(PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_MATH);
                                } else {
                                        $token->setTokenType(PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERATORPREFIX);
                                }
 
                                $this->_tokens[] = $token;
                                continue;
                        }
 
                        if ($token->getTokenType() == PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERATORINFIX && $token->getValue() == "+") {
                                if ($i == 0) {
                                        continue;
                                } else if (
                                                        (($previousToken->getTokenType() == PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_FUNCTION) && ($previousToken->getTokenSubType() == PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_STOP)) ||
                                                        (($previousToken->getTokenType() == PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_SUBEXPRESSION) && ($previousToken->getTokenSubType() == PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_STOP)) ||
                                                        ($previousToken->getTokenType() == PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERATORPOSTFIX) ||
                                                        ($previousToken->getTokenType() == PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERAND)
                                                ) {
                                        $token->setTokenSubType(PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_MATH);
                                } else {
                                        continue;
                                }
 
                                $this->_tokens[] = $token;
                                continue;
                        }
 
                        if ($token->getTokenType() == PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERATORINFIX && $token->getTokenSubType() == PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_NOTHING) {
                                if (strpos("<>=", substr($token->getValue(), 0, 1)) !== false) {
                                        $token->setTokenSubType(PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_LOGICAL);
                                } else if ($token->getValue() == "&") {
                                        $token->setTokenSubType(PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_CONCATENATION);
                                } else {
                                        $token->setTokenSubType(PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_MATH);
                                }
 
                                $this->_tokens[] = $token;
                                continue;
                        }
 
                        if ($token->getTokenType() == PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_OPERAND && $token->getTokenSubType() == PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_NOTHING) {
                                if (!is_numeric($token->getValue())) {
                                        if (strtoupper($token->getValue()) == "TRUE" || strtoupper($token->getValue() == "FALSE")) {
                                                $token->setTokenSubType(PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_LOGICAL);
                                        } else {
                                                $token->setTokenSubType(PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_RANGE);
                                        }
                                } else {
                                        $token->setTokenSubType(PHPExcel_Calculation_FormulaToken::TOKEN_SUBTYPE_NUMBER);
                                }
 
                                $this->_tokens[] = $token;
                                continue;
                        }
 
                        if ($token->getTokenType() == PHPExcel_Calculation_FormulaToken::TOKEN_TYPE_FUNCTION) {
                                if (strlen($token->getValue() > 0)) {
                                        if (substr($token->getValue(), 0, 1) == "@") {
                                                $token->setValue(substr($token->getValue(), 1));
                                        }
                                }
                        }
 
                $this->_tokens[] = $token;
                }
    }
}