<?php
/*
* This file is part of Psy Shell.
*
* (c) 2012-2020 Justin Hileman
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
namespace Psy\Output;
use Symfony\Component\Console\Output\StreamOutput;
/**
* ProcOutputPager class.
*
* A ProcOutputPager instance wraps a regular StreamOutput's stream. Rather
* than writing directly to the stream, it shells out to a pager process and
* gives that process the stream as stdout. This means regular *nix commands
* like `less` and `more` can be used to page large amounts of output.
*/
class ProcOutputPager extends StreamOutput implements OutputPager
{
private $proc;
private $pipe;
private $stream;
private $cmd;
/**
* Constructor.
*
* @param StreamOutput $output
* @param string $cmd Pager process command (default: 'less -R -S -F -X')
*/
public function __construct(StreamOutput $output, $cmd = 'less -R -S -F -X')
{
$this->stream = $output->getStream();
$this->cmd = $cmd;
}
/**
* Writes a message to the output.
*
* @param string $message A message to write to the output
* @param bool $newline Whether to add a newline or not
*
* @throws \RuntimeException When unable to write output (should never happen)
*/
public function doWrite($message, $newline)
{
$pipe = $this->getPipe();
if (false === @\fwrite($pipe, $message . ($newline ? PHP_EOL : ''))) {
// @codeCoverageIgnoreStart
// should never happen
throw new \RuntimeException('Unable to write output');
// @codeCoverageIgnoreEnd
}
\fflush($pipe);
}
/**
* Close the current pager process.
*/
public function close()
{
if (isset($this->pipe)) {
\fclose($this->pipe);
}
if (isset($this->proc)) {
$exit = \proc_close($this->proc);
if ($exit !== 0) {
throw new \RuntimeException('Error closing output stream');
}
}
$this->pipe = null;
$this->proc = null;
}
/**
* Get a pipe for paging output.
*
* If no active pager process exists, fork one and return its input pipe.
*/
private function getPipe()
{
if (!isset($this->pipe) || !isset($this->proc)) {
$desc = [['pipe', 'r'], $this->stream, \fopen('php://stderr', 'w')];
$this->proc = \proc_open($this->cmd, $desc, $pipes);
if (!\is_resource($this->proc)) {
throw new \RuntimeException('Error opening output stream');
}
$this->pipe = $pipes[0];
}
return $this->pipe;
}
}