<?php
/*
 * Smarty plugin
 * -------------------------------------------------------------
 * Name:     math
 * Version:  0.1
 * Date:     2002-04-15
 * File:     modifier.math.php
 * Type:     modifier
 * Purpose:  Simple math modifier, replaces 'x' in an equation
 *           with the template variable and calculates the result.
 * Examples: {$numbervar|math:"x * 10"}
 *           {$numbervar|math:"abs(x)"}
 *           {$arrayvar|@count|math:"x * 2"}
 * Install:  Drop into the plugin directory.
 * Author:   Linus McCabe, Linus@McCabe.nu, http://anticapslock.com
 * -------------------------------------------------------------
 */
   function smarty_modifier_math($string, $equation = '')
   {
       // Make sure only allowed functions are used in equations
       // Code from function.math.php
       preg_match_all("![a-zA-Z][a-zA-Z0-9]*!",$equation, $match);
       $allowed_funcs = array('int','abs','ceil','cos','exp','floor','log','log10',
                              'max','min','pi','pow','rand','round','sin','sqrt','srand','tan','x');
   
       foreach($match[0] as $curr_var) {
           if (!in_array($curr_var, $allowed_funcs)) {
               $smarty->trigger_error("math: function $curr_var not allowed");
               return;
           }
       }
      
      $str = '$res = ' . preg_replace('/(?<!\w)x(?!\w)/', "$string",  $equation). ';';
      eval($str);
      
      return $res;
   }
?>