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https://github.com/mcrumm/pecan

ReactPHP Shell, based on the Symfony Console component.
https://github.com/mcrumm/pecan

reactphp readline symfony-console

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ReactPHP Shell, based on the Symfony Console component.

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# Pecan



Event-driven, non-blocking shell for [ReactPHP](http://reactphp.org).



Pecan (`/pɪˈkɑːn/`) provides a non-blocking alternative to the shell provided in the [Symfony Console](https://github.com/symfony/console) component. Additionally, Pecan includes a basic, framework-agnostic shell component called `Drupe` that can be used as the basis for building custom shells.



## Shells



### Drupe



`Pecan\Drupe` is a standalone component for building event-driven console components.  I like to think of it as Pecan without the Shell.



Pass an `EventLoopInterface` to `start()` listening for input.



```

$loop  = \React\EventLoop\Factory::create();

$shell = new \Pecan\Drupe();



// $shell->start() returns $loop to allow this chaining.

$shell->start($loop)->run();

```



### Drupe Events



 - `running` - The shell is running.

 - `data` - Data was received from `STDIN`.

 - `error` - Indicates an I/O problem.

 - `close` - The shell was closed.



### Shell



`Pecan\Shell` extends `Drupe` to provide an event-driven wrapper for a standard `Symfony\Component\Console\Application`.  It can be used as a drop-in replacement for `Symfony\Component\Console\Shell`.



>**Note**: To maintain a Symfony Console-like workflow, calling `$shell->run()` on `Pecan\Shell` starts the EventLoop, so make sure it gets called last.



### Shell Events



`Shell` emits the same events as `Drupe`.



## Readline



`Pecan\Readline` provides an interface for reading line-by-line input from `STDIN`.  This component is heavily inspired by, and strives for parity with the [NodeJS Readline Component](http://nodejs.org/api/readline.html).



### Readline Events



 - `line` - A line has been read from `STDIN`.

 - `pause` - Reading from the stream has been paused.

 - `resume` - Reading from the stream has resumed.

 - `error` - The input stream encountered an error.

 - `close` - Then input stream was closed.



## Console



`Pecan\Console\Console` provides a standard interface for working with `STDOUT` and `STDERR`.  It is inspired heavily by the [NodeJS Console Component](http://nodejs.org/api/console.html) and takes some functionality from the [Symfony Console Component](http://symfony.com)



### Output



The Output classes extend the base Console Output. `StreamOutput` wraps a single stream resource, while `ConsoleOutput` contains both the `STDOUT` and `STDERR` streams.



- `StreamOutputInterface`

- `ConsoleOutputInterface`

- `PecanOutput`



## Using Pecan



### Using Drupe as a Standalone Shell



```php

use Pecan\Drupe;



$loop   = \React\EventLoop\Factory::create();

$shell  = new Drupe();



// Example one-time callback to write the initial prompt.

// This resumes reading from STDIN and kicks off the shell.

$shell->once('running', function (Drupe $shell) {

    $shell->setPrompt('drupe> ')->prompt();

});



// Example callback for the data event.

// By convention, any call to write() will be followed by a call to prompt() 

// once the data has been written to the output stream.

$shell->on('data', function ($line, Drupe $shell) {



    $command = (!$line && strlen($line) == 0) ? false : rtrim($line);



    if ('exit' === $command || false === $command) {

        $shell->close();

    } else {

        $shell->writeln(sprintf(PHP_EOL.'// in: %s', $line));

    }



});



// Example callback for the close event.

$shell->on('close', function ($code, Drupe $shell) {

    $shell->writeln([

        '// Goodbye.',

        sprintf('// Shell exits with code %d', $code),

    ]);

});



$shell->start($loop)->run();

```



### Using Shell with Symfony Console Applications



Here is a shell that echoes back any input it receives, and then exits.



```php

// Pecan\Shell wraps a standard Console Application.

use Symfony\Component\Console\Application;

use Pecan\Shell;



$shell = new Shell(new Application('pecan'));



$shell->on('data', function($line, Shell $shell) {

    $shell->write($line)->then(function($shell) {

        $shell->close();

    });

});



$shell->run();

```



### Injecting An `EventLoopInterface` into `Pecan\Shell`



Unless you pass `\Pecan\Shell` an object implementing `EventLoopInterface` as its second constructor method, the `Shell` will get one from the EventLoop Factory.  Keep this in mind if you want to integrate Pecan into an existing ReactPHP project.



```php

use Symfony\Component\Console\Application;

use Pecan\Shell;



$loop  = \React\EventLoop\Factory::create();



// Do other things requiring $loop...



$shell = new Shell(new Application('pecan'), $loop);



// We must still let the shell run the EventLoop.

$shell->run();

```



### Example `exit` callback



```php

// Example callback for the exit event.

$shell->on('exit', function($code, \Pecan\Shell $shell) {

    $shell->emit('output', [

        [

            'Goodbye.',

            sprintf('// Shell exits with code %d', $code)

        ],

        true

    ]);

});

```