root/branches/1.3/lib/i18n/sfChoiceFormat.class.php

<?php

/**
 * sfChoiceFormat class file.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the BSD License.
 *
 * Copyright(c) 2004 by Qiang Xue. All rights reserved.
 *
 * To contact the author write to {@link mailto:qiang.xue@gmail.com Qiang Xue}
 * The latest version of PRADO can be obtained from:
 * {@link http://prado.sourceforge.net/}
 *
 * @author     Wei Zhuo <weizhuo[at]gmail[dot]com>
 * @version    $Id$
 * @package    symfony
 * @subpackage i18n
 */


/**
 * sfChoiceFormat class.
 * 
 * sfChoiceFormat converts between ranges of numeric values and string 
 * names for those ranges.
 *
 * A sfChoiceFormat splits the real number line -Inf to +Inf into two or 
 * more contiguous ranges. Each range is mapped to a string. 
 * sfChoiceFormat is generally used in a MessageFormat for displaying 
 * grammatically correct plurals such as "There are 2 files."
 *
 * <code>
 *  $string = '[0] are no files |[1] is one file |(1,Inf] are {number} files';
 *  
 *  $formatter = new sfMessageFormat(...); //init for a source
 *  $translated = $formatter->format($string);
 *
 *  $choice = new sfChoiceFormat();
 *  echo $choice->format($translated, 0); //shows "are no files"
 * </code>
 *
 * The message/string choices are separated by the pipe "|" followed
 * by a set notation of the form
 *  # <t>[1,2]</t> -- accepts values between 1 and 2, inclusive.
 *  # <t>(1,2)</t> -- accepts values between 1 and 2, excluding 1 and 2.
 *  # <t>{1,2,3,4}</t> -- only values defined in the set are accepted.
 *  # <t>[-Inf,0)</t> -- accepts value greater or equal to negative infinity 
 *                       and strictly less than 0
 * Any non-empty combinations of the delimiters of square and round brackets
 * are acceptable.
 *
 * @author Xiang Wei Zhuo <weizhuo[at]gmail[dot]com>
 * @version v1.0, last update on Fri Dec 24 20:46:16 EST 2004
 * @package    symfony
 * @subpackage i18n
 */
class sfChoiceFormat
{
  /**
   * The pattern to validate a set notation
   */
  protected $validate = '/[\(\[\{]|[-Inf\d:\s]+|,|[\+Inf\d\s:\?\-=!><%\|&\(\)]+|[\)\]\}]/ms';

  /**
   * The pattern to parse the formatting string.
   */
  protected $parse = '/\s*\|?([\(\[\{]([-Inf\d:\s]+,?[\+Inf\d\s:\?\-=!><%\|&\(\)]*)+[\)\]\}])\s*/';

  /**
   * The value for positive infinity.
   */
  protected $inf;

  /**
   * Constructor.
   */
  public function __construct()
  {
    $this->inf = -log(0);
  }

  /**
   * Determines if the given number belongs to a given set
   *
   * @param  float  $number the number to test.
   * @param  string $set    the set, in set notation.
   * @return boolean true if number is in the set, false otherwise.
   */
  public function isValid($number, $set)
  {
    $n = preg_match_all($this->validate, $set, $matches, PREG_SET_ORDER);

    if ($n < 3)
    {
      throw new sfException(sprintf('Invalid set "%s".', $set));
    }

    if (preg_match('/\{\s*n:([^\}]+)\}/', $set, $def))
    {
      return $this->isValidSetNotation($number, $def[1]);
    }

    $leftBracket = $matches[0][0];
    $rightBracket = $matches[$n - 1][0];

    $i = 0;
    $elements = array();

    foreach ($matches as $match)
    {
      $string = $match[0];
      if ($i != 0 && $i != $n - 1 && $string !== ',')
      {
        if ($string == '-Inf')
        {
          $elements[] = -1 * $this->inf;
        }
        else if ($string == '+Inf' || $string == 'Inf')
        {
          $elements[] = $this->inf;
        }
        else
        {
          $elements[] = floatval($string);
        }
      }
      $i++;
    }
    $total = count($elements);
    $number = floatval($number);

    if ($leftBracket == '{' && $rightBracket == '}')
    {
      return in_array($number, $elements);
    }

    $left = false;
    if ($leftBracket == '[')
    {
      $left = $number >= $elements[0];
    }
    else if ($leftBracket == '(')
    {
      $left = $number > $elements[0];
    }

    $right = false;
    if ($rightBracket == ']')
    {
      $right = $number <= $elements[$total - 1];
    }
    else if ($rightBracket == ')')
    {
      $right = $number < $elements[$total - 1];
    }

    if ($left && $right)
    {
      return true;
    }

    return false;
  }

  protected function isValidSetNotation($number, $set)
  {
    $str = '$result = '.str_replace('n', '$number', $set).';';
    try
    {
      eval($str);
      return $result;
    }
    catch (Exception $e)
    {
      return false;
    }
  }

  /**
   * Parses a choice string and get a list of sets and a list of strings corresponding to the sets.
   *
   * @param  string $string the string containing the choices
   * @return array array($sets, $strings)
   */
  public function parse($string)
  {
    $n = preg_match_all($this->parse, $string, $matches, PREG_OFFSET_CAPTURE);
    $sets = array();
    foreach ($matches[1] as $match)
    {
      $sets[] = $match[0];
    }

    $offset = $matches[0];
    $strings = array();
    for ($i = 0; $i < $n; $i++)
    {
      $len = strlen($offset[$i][0]);
      $begin = $i == 0 ? $len : $offset[$i][1] + $len;
      $end = $i == $n - 1 ? strlen($string) : $offset[$i + 1][1];
      $strings[] = substr($string, $begin, $end - $begin);
    }

    return array($sets, $strings);
  }

  /**
   * For the choice string, and a number, find and return the string that satisfied the set within the choices.
   *
   * @param  string $string   the choices string.
   * @param  float  $number   the number to test.
   * @return string the choosen string.
   */
  public function format($string, $number)
  {
    list($sets, $strings) = $this->parse($string);
    $total = count($sets);
    for ($i = 0; $i < $total; $i++)
    {
      if ($this->isValid($number, $sets[$i]))
      {
        return $strings[$i];
      }
    }

    return false;
  }
}