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Bitmap, also called bit array is a data structure that compactly store set of values as bits of integer. More data can be read at http://en.wikipedia.org/wiki/Bit_array.
It is useful when required compact way to represent combination of values and simple manipulations with them. One byte can represent eight independent values.
composer require sokil/php-bitmap
Lets see example. Errors in PHP represents as constants:
E_ERROR = 1 (0);
E_WARNING = 2 (1);
E_PARSE = 4 (2);
E_NOTICE = 8 (3);
E_CORE_ERROR = 16 (4);
E_CORE_WARNING = 32 (5);
E_COMPILE_ERROR = 64 (6);
E_COMPILE_WARNING = 128 (7);
E_USER_ERROR = 256 (8);
E_USER_WARNING = 512 (9);
E_USER_NOTICE = 1024 (10);
E_STRICT = 2048 (11);
E_RECOVERABLE_ERROR = 4096 (12);
E_DEPRECATED = 8192 (13);
E_USER_DEPRECATED = 16384 (14);
E_ALL = 32767 (15);
Every error level represent logical "1", and combination of all this values may be represent only by two bytes. E_ERROR represent first bit of byte, E_WARNING - second, etc.
Combination of E_WARNING and E_NOTICE in binary system is "1010" or 10 in decimal system.
Class that represents bitmap of PHP errors:
class PhpError extends \Sokil\Bitmap { /** * Show errors * Set first bit, which represents E_ERROR, to "1" */ public function showErrors() { $this->setBit(0); return $this; } /** * Hide errors * Set first bit, which represents E_ERROR, to "0" */ public function hideErrors() { $this->unsetBit(0); return $this; } /** * Check if errors shown * Check if first bit set to 1 */ public function isErrorsShown() { return $this->isBitSet(0); } /** * Show warnings * Set second bit, which represents E_WARNING, to "1" */ public function showWarnings() { $this->setBit(1); return $this; } /** * Hide warnings * Set second bit, which represents E_WARNING, to "0" */ public function hideWarnings() { $this->unsetBit(1); return $this; } /** * Check if warnings shown * Check if second bit set to 1 */ public function isWarningsShown() { return $this->isBitSet(1); } }
Now we can easely manipulate with errors:
// load current error levels $error = new PhpError(error_reporting()); // enable errors and warnings $error->showErrors()->showWarnings(); // set error reporting error_reporting($error->toInt()); // check if warnings shown var_dump($error->isWarningsShown()); // value may be set by mask // E_USER_ERROR | E_USER_WARNING is 256 + 512; $error->setBitsByMask(E_USER_ERROR | E_USER_WARNING);