search/classes/skip_future_documents_iterator.php

   1 <?php
   2 // This file is part of Moodle - http://moodle.org/
   3 //
   4 // Moodle is free software: you can redistribute it and/or modify
   5 // it under the terms of the GNU General Public License as published by
   6 // the Free Software Foundation, either version 3 of the License, or
   7 // (at your option) any later version.
   8 //
   9 // Moodle is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13 //
  14 // You should have received a copy of the GNU General Public License
  15 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 /**
  18  * Iterator for skipping search recordset documents that are in the future.
  19  *
  20  * @package core_search
  21  * @copyright 2017 The Open University
  22  * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  23  */
  24
  25 namespace core_search;
  26
  27 defined('MOODLE_INTERNAL') || die();
  28
  29 /**
  30  * Iterator for skipping search recordset documents that are in the future.
  31  *
  32  * This iterator stops iterating if it receives a document that was modified later than the
  33  * specified cut-off time (usually current time).
  34  *
  35  * This iterator assumes that its parent iterator returns documents in modified order (which is
  36  * required to be the case for search indexing). This means we will stop retrieving data from the
  37  * recordset
  38  *
  39  * @copyright 2017 The Open University
  40  * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  41  */
  42 class skip_future_documents_iterator implements \Iterator {
  43     /** @var \Iterator Parent iterator */
  44     protected $parent;
  45
  46     /** @var int Cutoff time; anything later than this will cause the iterator to stop */
  47     protected $cutoff;
  48
  49     /** @var mixed Current value of iterator */
  50     protected $currentdoc;
  51
  52     /** @var bool True if current value is available */
  53     protected $gotcurrent;
  54
  55     /**
  56      * Constructor.
  57      *
  58      * @param \Iterator $parent Parent iterator, must return search documents in modified order
  59      * @param int $cutoff Cut-off time, default is current time
  60      */
  61     public function __construct(\Iterator $parent, $cutoff = 0) {
  62         $this->parent = $parent;
  63         if ($cutoff) {
  64             $this->cutoff = $cutoff;
  65         } else {
  66             $this->cutoff = time();
  67         }
  68     }
  69
  70     public function current() {
  71         if (!$this->gotcurrent) {
  72             $this->currentdoc = $this->parent->current();
  73             $this->gotcurrent = true;
  74         }
  75         return $this->currentdoc;
  76     }
  77
  78     public function next() {
  79         $this->parent->next();
  80         $this->gotcurrent = false;
  81     }
  82
  83     public function key() {
  84         return $this->parent->key();
  85     }
  86
  87     public function valid() {
  88         // Check that the parent is valid.
  89         if (!$this->parent->valid()) {
  90             return false;
  91         }
  92
  93         if ($doc = $this->current()) {
  94             // This document is valid if the modification date is before the cutoff.
  95             return $doc->get('modified') <= $this->cutoff;
  96         } else {
  97             // If the document is false/null, allow iterator to continue.
  98             return true;
  99         }
 100     }
 101
 102     public function rewind() {
 103         $this->parent->rewind();
 104         $this->gotcurrent = false;
 105     }
 106 }