<?php

/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_Validate
 * @copyright  Copyright (c) 2005-2008 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 * @version    $Id: Alpha.php 8064 2008-02-16 10:58:39Z thomas $
 */

/**
 * @see Zend_Validate_Abstract
 */
require_once 'external/Zend/Validate/Abstract.php';

/**
 * @category   Zend
 * @package    Zend_Validate
 * @copyright  Copyright (c) 2005-2008 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */
class Zend_Validate_Alpha extends Zend_Validate_Abstract {
  /**
   * Validation failure message key for when the value contains non-alphabetic characters
   */
  const NOT_ALPHA = 'notAlpha';
  
  /**
   * Validation failure message key for when the value is an empty string
   */
  const STRING_EMPTY = 'stringEmpty';
  
  /**
   * Whether to allow white space characters; off by default
   *
   * @var boolean
   */
  public $allowWhiteSpace;
  
  /**
   * Alphabetic filter used for validation
   *
   * @var Zend_Filter_Alpha
   */
  protected static $_filter = null;
  
  /**
   * Validation failure message template definitions
   *
   * @var array
   */
  protected $_messageTemplates = array(self::NOT_ALPHA => "'%value%' has not only alphabetic characters", 
      self::STRING_EMPTY => "'%value%' is an empty string");

  /**
   * Sets default option values for this instance
   *
   * @param  boolean $allowWhiteSpace
   * @return void
   */
  public function __construct($allowWhiteSpace = false) {
    $this->allowWhiteSpace = (boolean)$allowWhiteSpace;
  }

  /**
   * Defined by Zend_Validate_Interface
   *
   * Returns true if and only if $value contains only alphabetic characters
   *
   * @param  string $value
   * @return boolean
   */
  public function isValid($value) {
    $valueString = (string)$value;
    
    $this->_setValue($valueString);
    
    if ('' === $valueString) {
      $this->_error(self::STRING_EMPTY);
      return false;
    }
    
    if (null === self::$_filter) {
      /**
       * @see Zend_Filter_Alpha
       */
      require_once 'external/Zend/Filter/Alpha.php';
      self::$_filter = new Zend_Filter_Alpha();
    }
    
    self::$_filter->allowWhiteSpace = $this->allowWhiteSpace;
    
    if ($valueString !== self::$_filter->filter($valueString)) {
      $this->_error(self::NOT_ALPHA);
      return false;
    }
    
    return true;
  }

}
