# PSR-7 Message Implementation
This repository co
ntains a full [PSR-7](http://www.php-fig.org/psr/psr-7/)
message implementation, several stream decorators, and some helpful
functio
nality like query string parsing.
[![Build Status](https://travis-ci.org/guzzle/psr7.svg?branch=master)](https://travis-ci.org/guzzle/psr7)
# Stream implementation
This package comes with a number of stream implementations and stream
decorators.
## AppendStream
`GuzzleHttpPsr7AppendStream`
Reads from multiple streams, one after the other.
```php
use GuzzleHttpPsr7;
$a = Psr7stream_for('abc, ');
$b = Psr7stream_for('123.');
$composed = new Psr7AppendStream([$a, $b]);
$composed->addStream(Psr7stream_for(' Above all listen to me'));
echo $composed; // abc, 123. Above all listen to me.
```
## BufferStream
`GuzzleHttpPsr7BufferStream`
Provides a buffer stream that can be written to fill a buffer, and read
from to remove bytes from the buffer.
This stream returns a "hwm" m
etadata value that tells upstream co
nsumers
what the co
nfigured high water mark of the stream is, or the maximum
preferred size of the buffer.
```php
use GuzzleHttpPsr7;
// When more than 1024 bytes are in the buffer, it will begin returning
// false to writes. This is an indication that writers should slow down.
$buffer = new Psr7BufferStream(1024);
```
## CachingStream
The CachingStream is used to allow seeking over previously read bytes on
non-seekable streams. This can be useful when transferring a non-seekable
entity body fails due to needing to rewind the stream (for example, resulting
from a redirect). Data that is read from the remote stream will be buffered in
a PHP temp stream so that previously read bytes are cached first in memory,
then on disk.
```php
use GuzzleHttpPsr7;
$original = Psr7stream_for(fopen('http://www.google.com', 'r'));
$stream = new Psr7CachingStream($original);
$stream->read(1024);
echo $stream->tell();
// 1024
$stream->seek(0);
echo $stream->tell();
// 0
```
## Dro
ppingStream
`GuzzleHttpPsr7DroppingStream`
Stream decorator that begins dropping data o
nce the size of the underlying
stream becomes too full.
```php
use GuzzleHttpPsr7;
// Create an empty stream
$stream = Psr7stream_for();
// Start dropping data when the stream has more than 10 bytes
$dropping = new Psr7DroppingStream($stream, 10);
$dropping->write('01234567890123456789');
echo $stream; // 0123456789
```
## FnStream
`GuzzleHttpPsr7FnStream`
Compose stream implementations b
ased on a hash of functions.
Allows for easy testing and extension of a provided stream without needing
to create a co
ncrete class for a simple extension point.
```php
use GuzzleHttpPsr7;
$stream = Psr7stream_for('hi');
$fnStream = Psr7FnStream::decorate($stream, [
'rewind' => function () use ($stream) {
echo 'A
bout to rewind - ';
$stream->rewind();
echo 'rewound!';
}
]);
$fnStream->rewind();
// Outputs: A
bout to rewind - rewound!
```
## InflateStream
`GuzzleHttpPsr7InflateStream`
Uses PHP's zlib.inflate filter to inflate deflate or gzipped content.
This stream decorator skips the first 10 bytes of the given stream to remove
the gzip header, co
nverts the provided stream to a PHP stream resource,
then appends the zlib.inflate filter. The stream is then co
nverted back
to a Guzzle stream resource to be used as a Guzzle stream.
## LazyOpenStream
`GuzzleHttpPsr7LazyOpenStream`
Lazily reads or writes to a file that is opened o
nly after an IO operation
take place on the stream.
```php
use GuzzleHttpPsr7;
$stream = new Psr7LazyOpenStream('/path/to/file', 'r');
// The file has not yet been opened...
echo $stream->read(10);
// The file is opened and read from o
nly when needed.
```
## LimitStream
`GuzzleHttpPsr7LimitStream`
LimitStream can be used to read a subset or slice of an existing stream object.
This can be useful for breaking a large file into smaller pieces to be sent in
chunks (e.g. Amazon S3's multipart upload API).
```php
use GuzzleHttpPsr7;
$original = Psr7stream_for(fopen('/tmp/test.txt', 'r+'));
echo $original->getSize();
// >>> 1048576
// Limit the size of the body to 1024 bytes and start reading from byte 2048
$stream = new Psr7LimitStream($original, 1024, 2048);
echo $stream->getSize();
// >>> 1024
echo $stream->tell();
// >>> 0
```
## MultipartStream
`GuzzleHttpPsr7MultipartStream`
Stream that when read returns bytes for a streaming multipart or
multipart/form-data stream.
## NoSeekStream
`GuzzleHttpPsr7NoSeekStream`
NoSeekStream wraps a stream and does not allow seeking.
```php
use GuzzleHttpPsr7;
$original = Psr7stream_for('foo');
$noSeek = new Psr7NoSeekStream($original);
echo $noSeek->read(3);
// foo
var_export($noSeek->isSeekable());
// false
$noSeek->seek(0);
var_export($noSeek->read(3));
// NULL
```
## PumpStream
`GuzzleHttpPsr7PumpStream`
Provides a read o
nly stream that pumps data from a PHP callable.
When invoking the provided callable, the PumpStream will pass the amount of
data requested to read to the callable. The callable can choose to ignore
this value and return fewer or more bytes than requested. Any extra data
returned by the provided callable is buffered internally until drained using
the read() function of the PumpStream. The provided callable MUST return
false when there is no more data to read.
## Implementing stream decorators
Creating a stream decorator is very easy thanks to the
`GuzzleHttpPsr7StreamDecoratorTrait`. This trait provides methods that
implement `PsrHttpMessageStreamInterface` by proxying to an underlying
stream. Just `use` the `StreamDecoratorTrait` and implement your custom
methods.
For example, let's say we wanted to call a specific function each time the last
byte is read from a stream. This could be implemented by overriding the
`read()` method.
```php
use PsrHttpMessageStreamInterface;
use GuzzleHttpPsr7StreamDecoratorTrait;
class EofCallbackStream implements StreamInterface
{
use StreamDecoratorTrait;
private $callback;
public function __co
nstruct(StreamInterface $stream, callable $cb)
{
$this->stream = $stream;
$this->callback = $cb;
}
public function read($length)
{
$result = $this->stream->read($length);
// Invoke the callback when EOF is hit.
if ($this->eof()) {
call_user_func($this->callback);
}
return $result;
}
}
```
This decorator could be added to any existing stream and used like so:
```php
use GuzzleHttpPsr7;
$original = Psr7stream_for('foo');
$eofStream = new EofCallbackStream($original, function () {
echo 'EOF!';
});
$eofStream->read(2);
$eofStream->read(1);
// echoes "EOF!"
$eofStream->seek(0);
$eofStream->read(3);
// echoes "EOF!"
```
## PHP StreamWrapper
You can use the `GuzzleHttpPsr7StreamWrapper` class if you need to use a
PSR-7 stream as a PHP stream resource.
Use the `GuzzleHttpPsr7StreamWrapper::getResource()` method to create a PHP
stream from a PSR-7 stream.
```php
use GuzzleHttpPsr7StreamWrapper;
$stream = GuzzleHttpPsr7stream_for('hello!');
$resource = StreamWrapper::getResource($stream);
echo fread($resource, 6); // outputs hello!
```
# Function API
There are various functions available under the `GuzzleHttpPsr7` namespace.
## `function str`
`function str(MessageInterface $message)`
Returns the string representation of an HTTP message.
```php
$request = new GuzzleHttpPsr7Request('GET', 'http://example.com');
echo GuzzleHttpPsr7str($request);
```
## `function uri_for`
`function uri_for($uri)`
This function accepts a string or `PsrHttpMessageUriInterface` and returns a
UriInterface for the given value. If the value is already a `UriInterface`, it
is returned as-is.
```php
$uri = GuzzleHttpPsr7or('http://example.com');
assert($uri === GuzzleHttpPsr7or($uri));
```
## `function stream_for`