Online PHP editor | output for hq4L2

<?php /** * Implements a read/write buffer. */ class Buffer { protected $eof = false; protected $indexRead = 0; protected $indexWrite = 0; protected $buffer = []; public function write($bytes) { if ($bytes === null) { $this->eof = true; } else { $this->buffer[$this->indexWrite++] = $bytes; } } public function read($length = 4096) { if (!$this->buffer) { return $this->eof ? null : ''; } $output = ''; $outputLength = 0; while ($this->indexRead < $this->indexWrite) { $chunk = $this->buffer[$this->indexRead]; $chunkLength = \strlen($chunk); if ($outputLength + $chunkLength == $length) { unset($this->buffer[$this->indexRead++]); $output .= $chunk; return $output; } if ($outputLength + $chunkLength > $length) { $slice = $length - $outputLength; $this->buffer[$this->indexRead] = \substr($chunk, $slice); $output .= \substr($chunk, 0, $slice); return $output; } unset($this->buffer[$this->indexRead++]); $output .= $chunk; $outputLength += $chunkLength; } return $output; } } $b = new Buffer(); $b->write('ABCDEFGHIJ'); $b->write('KLMNOPQRSTUVWXYZ'); var_dump($b->read(3)); var_dump($b->read(3)); var_dump($b->read(3)); var_dump($b->read(3)); var_dump($b->read(3)); var_dump($b->read(3)); var_dump($b->read(3)); var_dump($b->read(3)); var_dump($b->read(3)); var_dump($b->read(3)); var_dump($b->read(3)); var_dump($b->read(3)); var_dump($b->read(3)); var_dump($b->read(3)); var_dump($b->read(3)); var_dump($b->read(3)); var_dump($b->read(3)); echo 'Writing more...' . PHP_EOL; $b->write('01234567890'); var_dump($b->read(3)); var_dump($b->read(3)); var_dump($b->read(3)); var_dump($b->read(3)); var_dump($b->read(3)); echo 'EOF...' . PHP_EOL; $b->write(null); var_dump($b->read(3)); var_dump($b->read(3)); var_dump($b->read(3));