readme

Author: sokil

README.md

@@ -1,4 +1,122 @@
 php-bitmap
 ==========
 
-Operations with bitmap
+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.
+
+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:
+
+```php
+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 showErrors()
+    {
+        $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 showWarnings()
+    {
+        $this->unsetBit(1);
+        return $this;
+    }
+
+    /**
+     * Check if warnings shown
+     * Check if second bit set to 1
+     */
+    public function isWarningsShown()
+    {
+        return $this->isBitSet(1);
+    }
+}
+```
+
+Now we can easely manipulate with errors:
+```php
+
+// load current error levels
+$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);
+```