3 * @copyright Copyright (C) 2021, Friendica
5 * @license GNU AGPL version 3 or any later version
7 * This program is free software: you can redistribute it and/or modify
8 * it under the terms of the GNU Affero General Public License as
9 * published by the Free Software Foundation, either version 3 of the
10 * License, or (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU Affero General Public License for more details.
17 * You should have received a copy of the GNU Affero General Public License
18 * along with this program. If not, see <https://www.gnu.org/licenses/>.
22 namespace Friendica\Util;
25 * An iterator which returns lines from file in reversed order
27 * original code https://stackoverflow.com/a/10494801
29 class ReversedFileReader implements \Iterator
31 const BUFFER_SIZE = 4096;
32 const SEPARATOR = "\n";
49 public function __construct($filename)
51 $this->_fh = fopen($filename, 'r');
53 // this should use a custom exception.
54 throw \Exception("Unable to open $filename");
56 $this->filesize = filesize($filename);
63 public function _read($size)
66 fseek($this->_fh, $this->pos);
67 return fread($this->_fh, $size);
70 public function _readline()
72 $buffer = & $this->buffer;
74 if ($this->pos == 0) {
75 return array_pop($buffer);
77 if (count($buffer) > 1) {
78 return array_pop($buffer);
80 $buffer = explode(self::SEPARATOR, $this->_read(self::BUFFER_SIZE) . $buffer[0]);
84 public function next()
87 $this->value = $this->_readline();
90 public function rewind()
92 if ($this->filesize > 0) {
93 $this->pos = $this->filesize;
96 $this->buffer = explode(self::SEPARATOR, $this->_read($this->filesize % self::BUFFER_SIZE ?: self::BUFFER_SIZE));
101 public function key()
106 public function current()
111 public function valid()
113 return ! is_null($this->value);