Documentation for ThroughStream

README.md

@@ -37,6 +37,7 @@ descriptor based implementation with an in-memory write buffer.
   * [ReadableResourceStream](#readableresourcestream)
   * [WritableResourceStream](#writableresourcestream)
   * [DuplexResourceStream](#duplexresourcestream)
+  * [ThroughStream](#throughstream)
 * [Usage](#usage)
 * [Install](#install)
 * [Tests](#tests)
@@ -924,6 +925,53 @@ $buffer->softLimit = 8192;
 
 See also [`write()`](#write) for more details.
 
+### ThroughStream
+
+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));
+```
+
 ## Usage
 ```php
     $loop = React\EventLoop\Factory::create();

src/ThroughStream.php

@@ -5,6 +5,57 @@
 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));
+ * ```
+ *
+ * @see WritableStreamInterface::write()
+ * @see WritableStreamInterface::end()
+ * @see DuplexStreamInterface::close()
+ * @see WritableStreamInterface::pipe()
+ */
 class ThroughStream extends EventEmitter implements DuplexStreamInterface
 {
     private $readable = true;