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<?php |
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namespace Thruster\Component\HttpMessage; |
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use Psr\Http\Message\StreamInterface; |
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/** |
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* Class LimitStream |
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* |
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* @package Thruster\Component\HttpMessage |
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* @author Aurimas Niekis <[email protected]> |
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*/ |
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class LimitStream implements StreamInterface |
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{ |
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use StreamDecoratorTrait; |
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/** |
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* @var int Offset to start reading from |
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*/ |
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private $offset; |
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/** |
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* @var int Limit the number of bytes that can be read |
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*/ |
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private $limit; |
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/** |
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* @param StreamInterface $stream Stream to wrap |
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* @param int $limit Total number of bytes to allow to be read |
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* from the stream. Pass -1 for no limit. |
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* @param int|null $offset Position to seek to before reading (only |
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* works on seekable streams). |
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*/ |
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public function __construct( |
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StreamInterface $stream, |
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$limit = -1, |
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$offset = 0 |
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) { |
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$this->stream = $stream; |
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$this->setLimit($limit); |
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$this->setOffset($offset); |
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} |
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public function eof() |
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{ |
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// Always return true if the underlying stream is EOF |
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if ($this->stream->eof()) { |
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return true; |
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} |
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// No limit and the underlying stream is not at EOF |
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if ($this->limit == -1) { |
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return false; |
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} |
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return $this->stream->tell() >= $this->offset + $this->limit; |
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} |
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/** |
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* Returns the size of the limited subset of data |
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* {@inheritdoc} |
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*/ |
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public function getSize() |
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{ |
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if (null === ($length = $this->stream->getSize())) { |
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return null; |
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} elseif (-1 == $this->limit) { |
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return $length - $this->offset; |
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} else { |
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return min($this->limit, $length - $this->offset); |
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} |
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} |
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/** |
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* Allow for a bounded seek on the read limited stream |
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* {@inheritdoc} |
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*/ |
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public function seek($offset, $whence = SEEK_SET) |
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{ |
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if (SEEK_SET !== $whence || 0 > $offset) { |
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throw new \RuntimeException(sprintf( |
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'Cannot seek to offset % with whence %s', |
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$offset, |
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$whence |
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)); |
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} |
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$offset += $this->offset; |
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if (-1 !== $this->limit) { |
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if ($offset > $this->offset + $this->limit) { |
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$offset = $this->offset + $this->limit; |
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} |
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} |
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$this->stream->seek($offset); |
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} |
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/** |
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* Give a relative tell() |
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* {@inheritdoc} |
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*/ |
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public function tell() |
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{ |
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return $this->stream->tell() - $this->offset; |
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} |
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/** |
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* Set the offset to start limiting from |
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* |
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* @param int $offset Offset to seek to and begin byte limiting from |
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* |
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* @throws \RuntimeException if the stream cannot be seeked. |
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*/ |
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public function setOffset($offset) |
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{ |
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$current = $this->stream->tell(); |
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if ($current !== $offset) { |
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// If the stream cannot seek to the offset position, then read to it |
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if ($this->stream->isSeekable()) { |
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$this->stream->seek($offset); |
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} elseif ($current > $offset) { |
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throw new \RuntimeException("Could not seek to stream offset $offset"); |
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} else { |
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$this->stream->read($offset - $current); |
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} |
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} |
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$this->offset = $offset; |
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} |
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/** |
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* Set the limit of bytes that the decorator allows to be read from the |
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* stream. |
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* |
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* @param int $limit Number of bytes to allow to be read from the stream. |
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* Use -1 for no limit. |
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*/ |
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public function setLimit($limit) |
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{ |
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$this->limit = $limit; |
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} |
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public function read($length) |
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{ |
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if ($this->limit == -1) { |
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return $this->stream->read($length); |
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} |
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// Check if the current position is less than the total allowed |
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// bytes + original offset |
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$remaining = ($this->offset + $this->limit) - $this->stream->tell(); |
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if ($remaining > 0) { |
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// Only return the amount of requested data, ensuring that the byte |
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// limit is not exceeded |
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return $this->stream->read(min($remaining, $length)); |
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} |
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return ''; |
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} |
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} |
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In PHP it is possible to write to properties without declaring them. For example, the following is perfectly valid PHP code:
Generally, it is a good practice to explictly declare properties to avoid accidental typos and provide IDE auto-completion: