133 lines
3.0 KiB
PHP
133 lines
3.0 KiB
PHP
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<?php
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/**
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; under version 2
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* of the License (non-upgradable).
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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* Copyright (c) 2002-2020 (original work) 2014 Open Assessment Technologies SA
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*
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*/
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/**
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* Iterator over all triples
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*
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* @author joel bout <joel@taotesting.com>
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*/
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class common_persistence_sql_QueryIterator implements Iterator
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{
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private const CACHE_SIZE = 100;
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/**
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* @var common_persistence_SqlPersistence
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*/
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private $persistence;
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/**
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* @var string
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*/
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private $query;
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/**
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* @var array
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*/
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private $params;
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/**
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* Id of the current instance
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*
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* @var int
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*/
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private $currentResult;
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/**
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* Return statements of the last query
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*
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* @var array
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*/
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private $cache;
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/**
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* @var array
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*/
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private $types;
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/**
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* @var int
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*/
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private $limit;
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public function __construct(
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common_persistence_SqlPersistence $persistence,
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string $query,
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array $params = [],
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array $types = [],
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int $limit = self::CACHE_SIZE
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) {
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$this->persistence = $persistence;
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$this->query = $query;
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$this->params = $params;
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$this->types = $types;
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$this->limit = $limit;
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$this->rewind();
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}
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public function rewind()
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{
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$this->load(0);
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}
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/**
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* @return core_kernel_classes_Triple
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*/
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public function current()
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{
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return $this->cache[$this->currentResult];
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}
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public function key()
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{
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return $this->currentResult;
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}
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public function next()
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{
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if ($this->valid()) {
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$last = $this->key();
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$this->currentResult++;
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if (!isset($this->cache[$this->currentResult])) {
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$this->load($last + 1);
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}
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}
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}
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public function valid()
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{
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return !empty($this->cache);
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}
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/**
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* Loads the next n results, starting with $offset
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*
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* @param int $offset
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*/
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protected function load($offset)
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{
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$query = $this->persistence->getPlatForm()->limitStatement($this->query, $this->limit, $offset);
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$result = $this->persistence->query($query, $this->params, $this->types);
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$this->cache = [];
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$pos = $offset;
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while ($statement = $result->fetch()) {
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$this->cache[$pos++] = $statement;
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}
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$this->currentResult = $offset;
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}
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}
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