Read file backward
<?php
class ReverseFile implements Iterator
{
const BUFFER_SIZE = 4096;
const SEPARATOR = "\n";
public function __construct($filename)
{
$this->_fh = fopen($filename, 'r');
$this->_filesize = filesize($filename);
$this->_pos = -1;
$this->_buffer = null;
$this->_key = -1;
$this->_value = null;
}
public function _read($size)
{
$this->_pos -= $size;
fseek($this->_fh, $this->_pos);
return fread($this->_fh, $size);
}
public function _readline()
{
$buffer =& $this->_buffer;
while (true) {
if ($this->_pos == 0) {
return array_pop($buffer);
}
if (count($buffer) > 1) {
return array_pop($buffer);
}
$buffer = explode(self::SEPARATOR, $this->_read(self::BUFFER_SIZE) . $buffer[0]);
}
}
public function next()
{
++$this->_key;
$this->_value = $this->_readline();
}
public function rewind()
{
if ($this->_filesize > 0) {
$this->_pos = $this->_filesize;
$this->_value = null;
$this->_key = -1;
$this->_buffer = explode(self::SEPARATOR, $this->_read($this->_filesize % self::BUFFER_SIZE ?: self::BUFFER_SIZE));
$this->next();
}
}
public function key() { return $this->_key; }
public function current() { return $this->_value; }
public function valid() { return ! is_null($this->_value); }
}
$f = new ReverseFile(__DIR__. '/file');
foreach ($f as $line) echo $line, "\n";