# zbateson/stream-decorators

Psr7 stream decorators for character set conversion and common mail format content encodings.

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The goals of this project are to be:

* Well written
* Standards-compliant but forgiving
* Tested where possible

To include it for use in your project, please install via composer:

```
composer require zbateson/stream-decorators
```

## Php 7 Support Dropped

As of stream-decorators 2.0, support for php 7 has been dropped.

## Requirements

stream-decorators requires PHP 8.0 or newer.  Tested on 8.0, 8.1, 8.2 and 8.3.

## New in 2.0 and 2.1

Support for guzzlehttp/psr7 1.9 dropped, min supported version is 2.0.

zbateson/mb-wrapper has been updated to 2.0 as well, which throws an UnsupportedCharsetException converting from/to an unsupported charset, which changes the behaviour of CharsetStream.

Two new classes are introduced in 2.1, DecoratedCachingStream and a TellZeroStream.

## Usage

```php
$stream = GuzzleHttp\Psr7\Utils::streamFor($handle);
$b64Stream = new ZBateson\StreamDecorators\Base64Stream($stream);
$charsetStream = new ZBateson\StreamDecorators\CharsetStream($b64Stream, 'UTF-32', 'UTF-8');

while (($line = GuzzleHttp\Psr7\Utils::readLine()) !== false) {
    echo $line, "\r\n";
}

```

Note that CharsetStream, depending on the target encoding, may return multiple bytes when a single 'char' is read.  If using php's 'fread', this will result in a warning:

'read x bytes more data than requested (xxxx read, xxxx max) - excess data will be lost

This is because the parameter to 'fread' is bytes, and so when CharsetStream returns, say, 4 bytes representing a single UTF-32 character, fread will truncate to the first byte when requesting '1' byte.  It is recommended to **not** convert to a stream handle (with StreamWrapper) for this reason when using CharsetStream.

The library consists of the following Psr\Http\Message\StreamInterface implementations:
* ZBateson\StreamDecorators\Base64Stream - decodes on read and encodes on write to base64.
* ZBateson\StreamDecorators\CharsetStream - encodes from $streamCharset to $stringCharset on read, and vice-versa on write.
* ZBateson\StreamDecorators\ChunkSplitStream - splits written characters into lines of $lineLength long (stream implementation of php's chunk_split).
* ZBateson\StreamDecorators\DecoratedCachingStream - a caching stream that writes to a decorated stream, and reads from the cached undecorated stream, so for instance a stream could be passed, and decorated with a Base64Stream, and when read, the returned bytes would be base64 encoded.
* ZBateson\StreamDecorators\NonClosingStream - overrides close() and detach(), and simply unsets the attached stream without closing it.
* ZBateson\StreamDecorators\PregReplaceFilterStream - calls preg_replace on with passed arguments on every read() call.
* ZBateson\StreamDecorators\QuotedPrintableStream - decodes on read and encodes on write to quoted-printable.
* ZBateson\StreamDecorators\SeekingLimitStream - similar to GuzzleHttp's LimitStream, but maintains an internal current read position, seeking to it when read() is called, and seeking back to the wrapped stream's position after reading.
* ZBateson\StreamDecorators\TellZeroStream - tell() always returns '0' -- used by DecoratedCachingStream to wrap a BufferStream in a CachingStream.  CachingStream calls tell() on its wrapped stream, and BufferStream throws an exception, so TellZeroStream is used to wrap the internal BufferStream to mitigate that.
* ZBateson\StreamDecorators\UUStream - decodes on read, encodes on write to uu-encoded.

QuotedPrintableStream, Base64Stream and UUStream's constructors take a single argument of a StreamInterface.
CharsetStreams's constructor also takes $streamCharset and $stringCharset as arguments respectively, ChunkSplitStream
optionally takes a $lineLength argument (defaults to 76) and a $lineEnding argument (defaults to CRLF).
PregReplaceFilterStream takes a $pattern argument and a $replacement argument.  SeekingLimitStream takes optional
$limit and $offset parameters, similar to GuzzleHttp's LimitStream.

## License

BSD licensed - please see [license agreement](https://github.com/zbateson/stream-decorators/blob/master/LICENSE).