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
25namespace core_search;
26
27defined('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 */
42class 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}
107