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<?php
namespace r7r\cms\sys\models;
use DoesNotExistError;
use ArrayAccess;
use Iterator;
use Countable;
use r7r\cms\sys\Database;
/**
* An abstract class for a KVStorage
*/
abstract class KVStorage implements Countable, ArrayAccess, Iterator
{
private $keybuffer;
private $counter;
private $silent_mode;
private $common_vals;
private $stmt_get;
private $stmt_unset;
private $stmt_update;
private $stmt_create;
final protected function init(string $sqltable, array $common, Database $db)
{
$this->silent_mode = false;
$this->keybuffer = [];
$selector = "WHERE ";
$fields = "";
foreach ($common as $field => $val) {
$selector .= "`$field` = ? AND ";
$fields .= ", `$field`";
$this->common_vals[] = $val;
}
$this->stmt_get = $db->prepStmt("SELECT `value` FROM `$sqltable` $selector `key` = ?");
$this->stmt_unset = $db->prepStmt("DELETE FROM `$sqltable` $selector `key` = ?");
$this->stmt_update = $db->prepStmt("UPDATE `$sqltable` SET `value` = ? $selector `key` = ?");
$this->stmt_create = $db->prepStmt("INSERT INTO `$sqltable` (`key`, `value` $fields) VALUES (?,?" . str_repeat(",?", count($common)) . ")");
$get_keys = $db->prepStmt("SELECT `key` FROM `$sqltable` $selector 1");
$get_keys->execute($this->common_vals);
while ($sqlrow = $get_keys->fetch()) {
$this->keybuffer[] = $sqlrow["key"];
}
$this->counter = 0;
}
/**
* Enable silent mode.
*
* If the silent mode is enabled, the KVStorage behaves even more like a PHP array, i.e. it just returns NULL,
* if an unknown key was requested and does not throw an DoesNotExistError Exception.
*
* See also {@see KVStorage::disable_silent_mode()}
*/
final public function enable_silent_mode()
{
$this->silent_mode = true;
}
/**
* Disable silent mode.
*
* See also {@see KVStorage::enable_silent_mode()}
*/
final public function disable_silent_mode()
{
$this->silent_mode = false;
}
/* Countable interface implementation */
final public function count()
{
return count($this->keybuffer);
}
/* ArrayAccess interface implementation */
final public function offsetExists($offset)
{
return in_array($offset, $this->keybuffer);
}
final public function offsetGet($offset)
{
if ($this->offsetExists($offset)) {
$this->stmt_get->execute(array_merge($this->common_vals, [$offset]));
$sqlrow = $this->stmt_get->fetch();
$this->stmt_get->closeCursor();
return unserialize(base64_decode($sqlrow["value"]));
} elseif ($this->silent_mode) {
return null;
} else {
throw new DoesNotExistError();
}
}
final public function offsetUnset($offset)
{
if ($this->offsetExists($offset)) {
unset($this->keybuffer[array_search($offset, $this->keybuffer)]);
$this->keybuffer = array_merge($this->keybuffer);
$this->stmt_unset->execute(array_merge($this->common_vals, [$offset]));
$this->stmt_unset->closeCursor();
}
}
final public function offsetSet($offset, $value)
{
if ($this->offsetExists($offset)) {
$this->stmt_update->execute(array_merge([base64_encode(serialize($value))], $this->common_vals, [$offset]));
$this->stmt_update->closeCursor();
} else {
$this->stmt_create->execute(array_merge([$offset, base64_encode(serialize($value))], $this->common_vals));
$this->stmt_create->closeCursor();
$this->keybuffer[] = $offset;
}
}
/* Iterator interface implementation */
final public function rewind()
{
return $this->counter = 0;
}
final public function current()
{
return $this->offsetGet($this->keybuffer[$this->counter]);
}
final public function key()
{
return $this->keybuffer[$this->counter];
}
final public function next()
{
++$this->counter;
}
final public function valid()
{
return isset($this->keybuffer[$this->counter]);
}
}
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