source: sourcecode/application/libraries/PHPExcel/Calculation/Token/Stack.php @ 1

<?php
/**
 * PHPExcel
 *
 * Copyright (c) 2006 - 2014 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_Calculation
 * @copyright  Copyright (c) 2006 - 2014 PHPExcel (http://www.codeplex.com/PHPExcel)
 * @license     http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt   LGPL
 * @version     1.8.0, 2014-03-02
 */


/**
 * PHPExcel_Calculation_Token_Stack
 *
 * @category    PHPExcel_Calculation_Token_Stack
 * @package             PHPExcel_Calculation
 * @copyright   Copyright (c) 2006 - 2014 PHPExcel (http://www.codeplex.com/PHPExcel)
 */
class PHPExcel_Calculation_Token_Stack {

        /**
         *  The parser stack for formulae
         *
         *  @var mixed[]
         */
        private $_stack = array();

        /**
         *  Count of entries in the parser stack
         *
         *  @var integer
         */
        private $_count = 0;


        /**
         * Return the number of entries on the stack
         *
         * @return  integer
         */
        public function count() {
                return $this->_count;
        }       //      function count()

        /**
         * Push a new entry onto the stack
         *
         * @param  mixed  $type
         * @param  mixed  $value
         * @param  mixed  $reference
         */
        public function push($type, $value, $reference = NULL) {
                $this->_stack[$this->_count++] = array('type'           => $type,
                                                                                           'value'              => $value,
                                                                                           'reference'  => $reference
                                                                                          );
                if ($type == 'Function') {
                        $localeFunction = PHPExcel_Calculation::_localeFunc($value);
                        if ($localeFunction != $value) {
                                $this->_stack[($this->_count - 1)]['localeValue'] = $localeFunction;
                        }
                }
        }       //      function push()

        /**
         * Pop the last entry from the stack
         *
         * @return  mixed
         */
        public function pop() {
                if ($this->_count > 0) {
                        return $this->_stack[--$this->_count];
                }
                return NULL;
        }       //      function pop()

        /**
         * Return an entry from the stack without removing it
         *
         * @param   integer  $n  number indicating how far back in the stack we want to look
         * @return  mixed
         */
        public function last($n = 1) {
                if ($this->_count - $n < 0) {
                        return NULL;
                }
                return $this->_stack[$this->_count - $n];
        }       //      function last()

        /**
         * Clear the stack
         */
        function clear() {
                $this->_stack = array();
                $this->_count = 0;
        }

}       //      class PHPExcel_Calculation_Token_Stack