languages/utils/CLDRPluralRuleEvaluator.php

   1 <?php
   2 /**
   3  * Parse and evaluate a plural rule
   4  *
   5  * @author Niklas Laxstrom
   6  *
   7  * @copyright Copyright © 2010-2012, Niklas Laxström
   8  * @license http://www.gnu.org/copyleft/gpl.html GNU General Public License 2.0 or later
   9  * @file
  10  */
  11
  12 class CLDRPluralRuleEvaluator {
  13         /**
  14          * Evaluate a number against a set of plural rules. If a rule passes,
  15          * return the index of plural rule.
  16          *
  17          * @param int The number to be evaluated against the rules
  18          * @param array The associative array of plural rules in pluralform => rule format.
  19          * @return int The index of the plural form which passed the evaluation
  20          */
  21         public static function evaluate( $number, $rules ) {
  22                 $formIndex = 0;
  23                 if ( !$rules ) {
  24                         return 0;
  25                 }
  26                 foreach ( $rules as $form => $rule ) {
  27                         $parsedRule = self::parseCLDRRule( $rule, $number );
  28                         // FIXME eval is bad.
  29                         if ( eval( "return $parsedRule;" ) ) {
  30                                 return $formIndex;
  31                         }
  32                         $formIndex++;
  33                 }
  34                 return $formIndex;
  35         }
  36         private static function parseCLDRRule( $rule ) {
  37                 $rule = preg_replace( '/\bn\b/', '$number', $rule );
  38                 $rule = preg_replace( '/([^ ]+) mod (\d+)/', 'self::mod(\1,\2)', $rule );
  39                 $rule = preg_replace( '/([^ ]+) is not (\d+)/' , '\1!=\2', $rule );
  40                 $rule = preg_replace( '/([^ ]+) is (\d+)/', '\1==\2', $rule );
  41                 $rule = preg_replace( '/([^ ]+) not in (\d+)\.\.(\d+)/', '!self::in(\1,\2,\3)', $rule );
  42                 $rule = preg_replace( '/([^ ]+) not within (\d+)\.\.(\d+)/', '!self::within(\1,\2,\3)', $rule );
  43                 $rule = preg_replace( '/([^ ]+) in (\d+)\.\.(\d+)/', 'self::in(\1,\2,\3)', $rule );
  44                 $rule = preg_replace( '/([^ ]+) within (\d+)\.\.(\d+)/', 'self::within(\1,\2,\3)', $rule );
  45                 // AND takes precedence over OR
  46                 $andrule = '/([^ ]+) and ([^ ]+)/i';
  47                 while ( preg_match( $andrule, $rule ) ) {
  48                         $rule = preg_replace( $andrule, '(\1&&\2)', $rule );
  49                 }
  50                 $orrule = '/([^ ]+) or ([^ ]+)/i';
  51                 while ( preg_match( $orrule, $rule ) ) {
  52                         $rule = preg_replace( $orrule, '(\1||\2)', $rule );
  53                 }
  54
  55                 return $rule;
  56         }
  57
  58         private static function in( $num, $low, $high ) {
  59                 return is_int( $num ) && $num >= $low && $num <= $high;
  60         }
  61
  62         private static function within( $num, $low, $high ) {
  63                 return $num >= $low && $num <= $high;
  64         }
  65
  66         private static function mod( $num, $mod ) {
  67                 if ( is_int( $num ) ) {
  68                         return (int) fmod( $num, $mod );
  69                 }
  70                 return fmod( $num, $mod );
  71         }
  72 }