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|
<?php
namespace React\Stream;
use Evenement\EventEmitter;
use InvalidArgumentException;
/**
* The `ThroughStream` implements the
* [`DuplexStreamInterface`](#duplexstreaminterface) and will simply pass any data
* you write to it through to its readable end.
*
* ```php
* $through = new ThroughStream();
* $through->on('data', $this->expectCallableOnceWith('hello'));
*
* $through->write('hello');
* ```
*
* Similarly, the [`end()` method](#end) will end the stream and emit an
* [`end` event](#end-event) and then [`close()`](#close-1) the stream.
* The [`close()` method](#close-1) will close the stream and emit a
* [`close` event](#close-event).
* Accordingly, this is can also be used in a [`pipe()`](#pipe) context like this:
*
* ```php
* $through = new ThroughStream();
* $source->pipe($through)->pipe($dest);
* ```
*
* Optionally, its constructor accepts any callable function which will then be
* used to *filter* any data written to it. This function receives a single data
* argument as passed to the writable side and must return the data as it will be
* passed to its readable end:
*
* ```php
* $through = new ThroughStream('strtoupper');
* $source->pipe($through)->pipe($dest);
* ```
*
* Note that this class makes no assumptions about any data types. This can be
* used to convert data, for example for transforming any structured data into
* a newline-delimited JSON (NDJSON) stream like this:
*
* ```php
* $through = new ThroughStream(function ($data) {
* return json_encode($data) . PHP_EOL;
* });
* $through->on('data', $this->expectCallableOnceWith("[2, true]\n"));
*
* $through->write(array(2, true));
* ```
*
* The callback function is allowed to throw an `Exception`. In this case,
* the stream will emit an `error` event and then [`close()`](#close-1) the stream.
*
* ```php
* $through = new ThroughStream(function ($data) {
* if (!is_string($data)) {
* throw new \UnexpectedValueException('Only strings allowed');
* }
* return $data;
* });
* $through->on('error', $this->expectCallableOnce()));
* $through->on('close', $this->expectCallableOnce()));
* $through->on('data', $this->expectCallableNever()));
*
* $through->write(2);
* ```
*
* @see WritableStreamInterface::write()
* @see WritableStreamInterface::end()
* @see DuplexStreamInterface::close()
* @see WritableStreamInterface::pipe()
*/
final class ThroughStream extends EventEmitter implements DuplexStreamInterface
{
private $readable = true;
private $writable = true;
private $closed = false;
private $paused = false;
private $drain = false;
private $callback;
public function __construct($callback = null)
{
if ($callback !== null && !\is_callable($callback)) {
throw new InvalidArgumentException('Invalid transformation callback given');
}
$this->callback = $callback;
}
public function pause()
{
$this->paused = true;
}
public function resume()
{
if ($this->drain) {
$this->drain = false;
$this->emit('drain');
}
$this->paused = false;
}
public function pipe(WritableStreamInterface $dest, array $options = array())
{
return Util::pipe($this, $dest, $options);
}
public function isReadable()
{
return $this->readable;
}
public function isWritable()
{
return $this->writable;
}
public function write($data)
{
if (!$this->writable) {
return false;
}
if ($this->callback !== null) {
try {
$data = \call_user_func($this->callback, $data);
} catch (\Exception $e) {
$this->emit('error', array($e));
$this->close();
return false;
}
}
$this->emit('data', array($data));
if ($this->paused) {
$this->drain = true;
return false;
}
return true;
}
public function end($data = null)
{
if (!$this->writable) {
return;
}
if (null !== $data) {
$this->write($data);
// return if write() already caused the stream to close
if (!$this->writable) {
return;
}
}
$this->readable = false;
$this->writable = false;
$this->paused = true;
$this->drain = false;
$this->emit('end');
$this->close();
}
public function close()
{
if ($this->closed) {
return;
}
$this->readable = false;
$this->writable = false;
$this->closed = true;
$this->paused = true;
$this->drain = false;
$this->callback = null;
$this->emit('close');
$this->removeAllListeners();
}
}
|
