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liveuser |
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<?php
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namespace GuzzleHttp\Psr7;
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use Psr\Http\Message\StreamInterface;
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/**
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* Stream decorator that can cache previously read bytes from a sequentially
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* read stream.
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*/
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class CachingStream implements StreamInterface
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{
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use StreamDecoratorTrait;
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/** @var StreamInterface Stream being wrapped */
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private $remoteStream;
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/** @var int Number of bytes to skip reading due to a write on the buffer */
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private $skipReadBytes = 0;
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/**
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* We will treat the buffer object as the body of the stream
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*
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* @param StreamInterface $stream Stream to cache
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* @param StreamInterface $target Optionally specify where data is cached
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*/
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public function __construct(
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StreamInterface $stream,
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StreamInterface $target = null
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) {
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$this->remoteStream = $stream;
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$this->stream = $target ?: new Stream(fopen('php://temp', 'r+'));
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}
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public function getSize()
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{
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return max($this->stream->getSize(), $this->remoteStream->getSize());
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}
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public function rewind()
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{
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$this->seek(0);
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}
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public function seek($offset, $whence = SEEK_SET)
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{
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if ($whence == SEEK_SET) {
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$byte = $offset;
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} elseif ($whence == SEEK_CUR) {
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$byte = $offset + $this->tell();
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} elseif ($whence == SEEK_END) {
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$size = $this->remoteStream->getSize();
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if ($size === null) {
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$size = $this->cacheEntireStream();
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}
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$byte = $size + $offset;
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} else {
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throw new \InvalidArgumentException('Invalid whence');
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}
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$diff = $byte - $this->stream->getSize();
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if ($diff > 0) {
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// Read the remoteStream until we have read in at least the amount
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// of bytes requested, or we reach the end of the file.
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while ($diff > 0 && !$this->remoteStream->eof()) {
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$this->read($diff);
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$diff = $byte - $this->stream->getSize();
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}
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} else {
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// We can just do a normal seek since we've already seen this byte.
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$this->stream->seek($byte);
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}
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}
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public function read($length)
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{
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// Perform a regular read on any previously read data from the buffer
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$data = $this->stream->read($length);
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$remaining = $length - strlen($data);
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// More data was requested so read from the remote stream
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if ($remaining) {
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// If data was written to the buffer in a position that would have
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// been filled from the remote stream, then we must skip bytes on
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// the remote stream to emulate overwriting bytes from that
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// position. This mimics the behavior of other PHP stream wrappers.
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$remoteData = $this->remoteStream->read(
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$remaining + $this->skipReadBytes
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);
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if ($this->skipReadBytes) {
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$len = strlen($remoteData);
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$remoteData = substr($remoteData, $this->skipReadBytes);
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$this->skipReadBytes = max(0, $this->skipReadBytes - $len);
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}
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$data .= $remoteData;
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$this->stream->write($remoteData);
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}
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return $data;
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}
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public function write($string)
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{
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// When appending to the end of the currently read stream, you'll want
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// to skip bytes from being read from the remote stream to emulate
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// other stream wrappers. Basically replacing bytes of data of a fixed
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// length.
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$overflow = (strlen($string) + $this->tell()) - $this->remoteStream->tell();
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if ($overflow > 0) {
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$this->skipReadBytes += $overflow;
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}
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return $this->stream->write($string);
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}
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public function eof()
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{
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return $this->stream->eof() && $this->remoteStream->eof();
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}
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/**
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* Close both the remote stream and buffer stream
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*/
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public function close()
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{
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$this->remoteStream->close() && $this->stream->close();
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}
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private function cacheEntireStream()
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{
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$target = new FnStream(['write' => 'strlen']);
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Utils::copyToStream($this, $target);
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return $this->tell();
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}
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}
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