<?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_Search_Lucene
 * @subpackage Index
 * @copyright  Copyright (c) 2005-2007 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */


/**
 * A Term represents a word from text.  This is the unit of search.  It is
 * composed of two elements, the text of the word, as a string, and the name of
 * the field that the text occured in, an interned string.
 *
 * Note that terms may represent more than words from text fields, but also
 * things like dates, email addresses, urls, etc.
 *
 * @category   Zend
 * @package    Zend_Search_Lucene
 * @subpackage Index
 * @copyright  Copyright (c) 2005-2007 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */
class Zend_Search_Lucene_Index_Term
{
    /**
     * Field name or field number (depending from context)
     *
     * @var mixed
     */
    public $field;

    /**
     * Term value
     *
     * @var string
     */
    public $text;


    /**
     * Object constructor
     */
    public function __construct($text, $field = null)
    {
        $this->field = ($field === null)?  Zend_Search_Lucene::getDefaultSearchField() : $field;
        $this->text  = $text;
    }


    /**
     * Returns term key
     *
     * @return string
     */
    public function key()
    {
        return $this->field . chr(0) . $this->text;
    }

    /**
     * Get term prefix
     *
     * @param integer $length
     * @return string
     */
    public static function getPrefix($str, $length)
    {
        $prefixBytes = 0;
        $prefixChars = 0;
        while ($prefixBytes < strlen($str)  &&  $prefixChars < $length) {
            $charBytes = 1;
            if ((ord($str[$prefixBytes]) & 0xC0) == 0xC0) {
                $charBytes++;
                if (ord($str[$prefixBytes]) & 0x20 ) {
                    $charBytes++;
                    if (ord($str[$prefixBytes]) & 0x10 ) {
                        $charBytes++;
                    }
                }
            }

            if ($prefixBytes + $charBytes > strlen($str)) {
                // wrong character
                break;
            }

            $prefixChars++;
            $prefixBytes += $charBytes;
        }

        return substr($str, 0, $prefixBytes);
    }
}

