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<?php |
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/** |
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* File containing the class {@see \AppUtils\OutputBuffering}. |
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* |
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* @package Application Utils |
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* @subpackage Output Buffering |
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* @see \AppUtils\OutputBuffering |
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*/ |
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declare(strict_types=1); |
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namespace AppUtils; |
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/** |
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* Wrapper around the native PHP output buffering methods, |
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* using exceptions to avoid having to check the return |
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* values of the methods. |
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* |
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* It is limited to a typical output buffering usage: |
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* starting a buffer, and retrieving or flushing its contents, |
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* stopping the buffer in the process. Any more complex |
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* buffer usage will have to use the PHP functions. |
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* |
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* @package Application Utils |
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* @subpackage Output Buffering |
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* @author Sebastian Mordziol <[email protected]> |
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*/ |
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class OutputBuffering |
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{ |
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const ERROR_CANNOT_START = 91501; |
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const ERROR_CANNOT_GET_BUFFER = 91502; |
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const ERROR_BUFFER_NOT_STARTED = 91503; |
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const ERROR_CANNOT_STOP_BUFFER = 91504; |
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const ERROR_CANNOT_FLUSH_BUFFER = 91505; |
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/** |
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* @var int[] |
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*/ |
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private static $stack = array(); |
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/** |
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* @var int |
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*/ |
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private static $baseLevel = 0; |
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/** |
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* Checks whether any level of output buffering is currently active. |
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* |
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* NOTE: Assumes by default that 0 is the inactive buffer level. |
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* If this is not the case, see the {@see OutputBuffering::setBaseBufferLevel()} |
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* method to adjust it. |
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* |
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* @return bool |
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* @see OutputBuffering::setBaseBufferLevel() |
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*/ |
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public static function isActive() : bool |
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{ |
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return ob_get_level() > self::$baseLevel; |
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} |
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/** |
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* Starts a new output buffer. |
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* |
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* @throws OutputBuffering_Exception |
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* @see OutputBuffering::ERROR_CANNOT_START |
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*/ |
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public static function start() : void |
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{ |
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self::$stack[] = 1; |
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if(ob_start() === true) { |
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return; |
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} |
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throw new OutputBuffering_Exception( |
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'Cannot start output buffering.', |
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'ob_start returned false.', |
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self::ERROR_CANNOT_START |
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); |
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} |
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/** |
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* Stops the output buffer, discarding the captured content. |
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* |
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* @throws OutputBuffering_Exception |
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* @see OutputBuffering::ERROR_BUFFER_NOT_STARTED |
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* @see OutputBuffering::ERROR_CANNOT_STOP_BUFFER |
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*/ |
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public static function stop() : void |
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{ |
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self::_stop(); |
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if(ob_end_clean() !== false) |
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{ |
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return; |
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} |
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throw new OutputBuffering_Exception( |
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'Cannot stop the output buffer.', |
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'The ob_end_clean call returned false.', |
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self::ERROR_CANNOT_STOP_BUFFER |
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); |
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} |
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/** |
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* @throws OutputBuffering_Exception |
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*/ |
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private static function _stop() : void |
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{ |
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if(empty(self::$stack)) |
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{ |
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throw new OutputBuffering_Exception( |
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'Output buffering is not active', |
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'Tried to get the output buffer, but none was active.', |
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self::ERROR_BUFFER_NOT_STARTED |
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); |
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} |
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array_pop(self::$stack); |
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} |
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/** |
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* Flushes the captured output buffer to standard output. |
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* |
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* @throws OutputBuffering_Exception |
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* @see OutputBuffering::ERROR_BUFFER_NOT_STARTED |
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* @see OutputBuffering::ERROR_CANNOT_FLUSH_BUFFER |
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*/ |
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public static function flush() : void |
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{ |
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self::_stop(); |
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if(ob_end_flush() !== false) |
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{ |
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return; |
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} |
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throw new OutputBuffering_Exception( |
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'Cannot flush the output buffer.', |
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'ob_end_flush returned false.', |
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self::ERROR_CANNOT_FLUSH_BUFFER |
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); |
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} |
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/** |
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* Retrieves the current output buffer's contents, |
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* and stops the output buffer. |
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* |
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* @return string |
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* |
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* @throws OutputBuffering_Exception |
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* @see OutputBuffering::ERROR_BUFFER_NOT_STARTED |
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* @see OutputBuffering::ERROR_CANNOT_GET_BUFFER |
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*/ |
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public static function get() : string |
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{ |
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self::_stop(); |
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$content = ob_get_clean(); |
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if($content !== false) |
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{ |
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return $content; |
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} |
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throw new OutputBuffering_Exception( |
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'Cannot stop the output buffer.', |
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'ob_get_contents returned false.', |
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self::ERROR_CANNOT_GET_BUFFER |
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); |
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} |
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/** |
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* Configure the output buffer to work in unit testing |
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* mode, which assumes that the testing framework does |
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* some output buffering of its own. This skews the |
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* {@see OutputBuffering::isActive()} method, since it |
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* assumes the buffer level must be 0 to be inactive. |
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*/ |
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public static function enableUnitTesting() : void |
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{ |
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self::setBaseBufferLevel(1); |
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} |
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/** |
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* Sets the base output buffering level. Any level |
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* above this value is considered an active output |
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* buffering level. |
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* |
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* Use this in case scripts outside your control |
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* already have output buffering active. For example, |
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* if your script always runs with 1 output buffering |
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* level already being active, set the level to 1. |
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* |
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* @param int $level |
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*/ |
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public static function setBaseBufferLevel(int $level) : void |
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{ |
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self::$baseLevel = $level; |
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} |
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} |
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