/library/Zend/Search/Lucene/TermStreamsPriorityQueue.php

  1<?php
  2/**
  3 * Zend Framework
  4 *
  5 * LICENSE
  6 *
  7 * This source file is subject to the new BSD license that is bundled
  8 * with this package in the file LICENSE.txt.
  9 * It is also available through the world-wide-web at this URL:
 10 * http://framework.zend.com/license/new-bsd
 11 * If you did not receive a copy of the license and are unable to
 12 * obtain it through the world-wide-web, please send an email
 13 * to license@zend.com so we can send you a copy immediately.
 14 *
 15 * @category   Zend
 16 * @package    Zend_Search_Lucene
 17 * @subpackage Index
 18 * @copyright  Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
 19 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 20 * @version    $Id: TermStreamsPriorityQueue.php 24594 2012-01-05 21:27:01Z matthew $
 21 */
 22
 23/** Zend_Search_Lucene_Index_TermsStream_Interface */
 24require_once 'Zend/Search/Lucene/Index/TermsStream/Interface.php';
 25
 26
 27/**
 28 * @category   Zend
 29 * @package    Zend_Search_Lucene
 30 * @subpackage Index
 31 * @copyright  Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
 32 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 33 */
 34class Zend_Search_Lucene_TermStreamsPriorityQueue implements Zend_Search_Lucene_Index_TermsStream_Interface
 35{
 36    /**
 37     * Array of term streams (Zend_Search_Lucene_Index_TermsStream_Interface objects)
 38     *
 39     * @var array
 40     */
 41    protected $_termStreams;
 42
 43    /**
 44     * Terms stream queue
 45     *
 46     * @var Zend_Search_Lucene_Index_TermsPriorityQueue
 47     */
 48    protected $_termsStreamQueue = null;
 49
 50    /**
 51     * Last Term in a terms stream
 52     *
 53     * @var Zend_Search_Lucene_Index_Term
 54     */
 55    protected $_lastTerm = null;
 56
 57
 58    /**
 59     * Object constructor
 60     *
 61     * @param array $termStreams  array of term streams (Zend_Search_Lucene_Index_TermsStream_Interface objects)
 62     */
 63    public function __construct(array $termStreams)
 64    {
 65        $this->_termStreams = $termStreams;
 66
 67        $this->resetTermsStream();
 68    }
 69
 70    /**
 71     * Reset terms stream.
 72     */
 73    public function resetTermsStream()
 74    {
 75        /** Zend_Search_Lucene_Index_TermsPriorityQueue */
 76        require_once 'Zend/Search/Lucene/Index/TermsPriorityQueue.php';
 77
 78        $this->_termsStreamQueue = new Zend_Search_Lucene_Index_TermsPriorityQueue();
 79
 80        foreach ($this->_termStreams as $termStream) {
 81            $termStream->resetTermsStream();
 82
 83            // Skip "empty" containers
 84            if ($termStream->currentTerm() !== null) {
 85                $this->_termsStreamQueue->put($termStream);
 86            }
 87        }
 88
 89        $this->nextTerm();
 90    }
 91
 92    /**
 93     * Skip terms stream up to the specified term preffix.
 94     *
 95     * Prefix contains fully specified field info and portion of searched term
 96     *
 97     * @param Zend_Search_Lucene_Index_Term $prefix
 98     */
 99    public function skipTo(Zend_Search_Lucene_Index_Term $prefix)
100    {
101        $this->_termsStreamQueue = new Zend_Search_Lucene_Index_TermsPriorityQueue();
102
103        foreach ($this->_termStreams as $termStream) {
104            $termStream->skipTo($prefix);
105
106            if ($termStream->currentTerm() !== null) {
107                $this->_termsStreamQueue->put($termStream);
108            }
109        }
110
111        return $this->nextTerm();
112    }
113
114    /**
115     * Scans term streams and returns next term
116     *
117     * @return Zend_Search_Lucene_Index_Term|null
118     */
119    public function nextTerm()
120    {
121        while (($termStream = $this->_termsStreamQueue->pop()) !== null) {
122            if ($this->_termsStreamQueue->top() === null ||
123                $this->_termsStreamQueue->top()->currentTerm()->key() !=
124                            $termStream->currentTerm()->key()) {
125                // We got new term
126                $this->_lastTerm = $termStream->currentTerm();
127
128                if ($termStream->nextTerm() !== null) {
129                    // Put segment back into the priority queue
130                    $this->_termsStreamQueue->put($termStream);
131                }
132
133                return $this->_lastTerm;
134            }
135
136            if ($termStream->nextTerm() !== null) {
137                // Put segment back into the priority queue
138                $this->_termsStreamQueue->put($termStream);
139            }
140        }
141
142        // End of stream
143        $this->_lastTerm = null;
144
145        return null;
146    }
147
148    /**
149     * Returns term in current position
150     *
151     * @return Zend_Search_Lucene_Index_Term|null
152     */
153    public function currentTerm()
154    {
155        return $this->_lastTerm;
156    }
157
158    /**
159     * Close terms stream
160     *
161     * Should be used for resources clean up if stream is not read up to the end
162     */
163    public function closeTermsStream()
164    {
165        while (($termStream = $this->_termsStreamQueue->pop()) !== null) {
166            $termStream->closeTermsStream();
167        }
168
169        $this->_termsStreamQueue = null;
170        $this->_lastTerm         = null;
171    }
172}