/
CharsetStream.php
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/
CharsetStream.php
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<?php
/**
* This file is part of the ZBateson\StreamDecorator project.
*
* @license http://opensource.org/licenses/bsd-license.php BSD
*/
namespace ZBateson\StreamDecorators;
use GuzzleHttp\Psr7\StreamDecoratorTrait;
use Psr\Http\Message\StreamInterface;
use RuntimeException;
use ZBateson\MbWrapper\MbWrapper;
/**
* GuzzleHttp\Psr7 stream decoder extension for charset conversion.
*
* @author Zaahid Bateson
*/
class CharsetStream implements StreamInterface
{
use StreamDecoratorTrait;
/**
* @var MbWrapper the charset converter
*/
protected MbWrapper $converter;
/**
* @var string charset of the source stream
*/
protected string $streamCharset = 'ISO-8859-1';
/**
* @var string charset of strings passed in write operations, and returned
* in read operations.
*/
protected string $stringCharset = 'UTF-8';
/**
* @var int current read/write position
*/
private int $position = 0;
/**
* @var int number of $stringCharset characters in $buffer
*/
private int $bufferLength = 0;
/**
* @var string a buffer of characters read in the original $streamCharset
* encoding
*/
private string $buffer = '';
/**
* @var StreamInterface $stream
*/
private StreamInterface $stream;
/**
* @param StreamInterface $stream Stream to decorate
* @param string $streamCharset The underlying stream's charset
* @param string $stringCharset The charset to encode strings to (or
* expected for write)
*/
public function __construct(StreamInterface $stream, string $streamCharset = 'ISO-8859-1', string $stringCharset = 'UTF-8')
{
$this->stream = $stream;
$this->converter = new MbWrapper();
$this->streamCharset = $streamCharset;
$this->stringCharset = $stringCharset;
}
/**
* Overridden to return the position in the target encoding.
*/
public function tell() : int
{
return $this->position;
}
/**
* Returns null, getSize isn't supported
*
* @return null
*/
public function getSize() : ?int
{
return null;
}
/**
* Not supported.
*
* @param int $offset
* @param int $whence
* @throws RuntimeException
*/
public function seek($offset, $whence = SEEK_SET) : void
{
throw new RuntimeException('Cannot seek a CharsetStream');
}
/**
* Overridden to return false
*/
public function isSeekable() : bool
{
return false;
}
/**
* Reads a minimum of $length characters from the underlying stream in its
* encoding into $this->buffer.
*
* Aligning to 4 bytes seemed to solve an issue reading from UTF-16LE
* streams and pass testReadUtf16LeToEof, although the buffered string
* should've solved that on its own.
*/
private function readRawCharsIntoBuffer(int $length) : void
{
$n = (int) \ceil(($length + 32) / 4.0) * 4;
while ($this->bufferLength < $n) {
$raw = $this->stream->read($n + 512);
if ($raw === '') {
return;
}
$this->buffer .= $raw;
$this->bufferLength = $this->converter->getLength($this->buffer, $this->streamCharset);
}
}
/**
* Returns true if the end of stream has been reached.
*/
public function eof() : bool
{
return ($this->bufferLength === 0 && $this->stream->eof());
}
/**
* Reads up to $length decoded chars from the underlying stream and returns
* them after converting to the target string charset.
*
* @param int $length
*/
public function read($length) : string
{
// let Guzzle decide what to do.
if ($length <= 0 || $this->eof()) {
return $this->stream->read($length);
}
$this->readRawCharsIntoBuffer($length);
$numChars = \min([$this->bufferLength, $length]);
$chars = $this->converter->getSubstr($this->buffer, $this->streamCharset, 0, $numChars);
$this->position += $numChars;
$this->buffer = $this->converter->getSubstr($this->buffer, $this->streamCharset, $numChars);
$this->bufferLength -= $numChars;
return $this->converter->convert($chars, $this->streamCharset, $this->stringCharset);
}
/**
* Writes the passed string to the underlying stream after converting it to
* the target stream encoding.
*
* @param string $string
* @return int the number of bytes written
*/
public function write($string) : int
{
$converted = $this->converter->convert($string, $this->stringCharset, $this->streamCharset);
$written = $this->converter->getLength($converted, $this->streamCharset);
$this->position += $written;
return $this->stream->write($converted);
}
}