# PSR-7 Message Implementation
This repository contains a full [PSR-7](http://www.php-fig.org/psr/psr-7/)
message implementation, several stream decorators, and some helpful
functionality 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" metadata value that tells upstream consumers
what the configured 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
```
## DroppingStream
`GuzzleHttpPsr7DroppingStream`
Stream decorator that begins dropping data once 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 based on a hash of functions.
Allows for easy testing and extension of a provided stream without needing
to create a concrete class for a simple extension point.
```php
use GuzzleHttpPsr7;
$stream = Psr7stream_for('hi');
$fnStream = Psr7FnStream::decorate($stream, [
'rewind' => function () use ($stream) {
echo 'About to rewind - ';
$stream->rewind();
echo 'rewound!';
}
]);
$fnStream->rewind();
// Outputs: About 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, converts the provided stream to a PHP stream resource,
then appends the zlib.inflate filter. The stream is then converted back
to a Guzzle stream resource to be used as a Guzzle stream.