Complex classes like HTMLPurifier_DefinitionCache_Serializer often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use HTMLPurifier_DefinitionCache_Serializer, and based on these observations, apply Extract Interface, too.
| 1 | <?php  | 
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| 3 | class HTMLPurifier_DefinitionCache_Serializer extends HTMLPurifier_DefinitionCache  | 
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| 4 | { | 
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| 5 | |||
| 6 | /**  | 
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| 7 | * @param HTMLPurifier_Definition $def  | 
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| 8 | * @param HTMLPurifier_Config $config  | 
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| 9 | * @return int|bool  | 
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| 10 | */  | 
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| 11 | public function add($def, $config)  | 
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| 12 |     { | 
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| 13 |         if (!$this->checkDefType($def)) { | 
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| 14 | return null;  | 
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| 15 | }  | 
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| 16 | $file = $this->generateFilePath($config);  | 
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| 17 |         if (file_exists($file)) { | 
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| 18 | return false;  | 
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| 19 | }  | 
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| 20 |         if (!$this->_prepareDir($config)) { | 
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| 21 | return false;  | 
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| 22 | }  | 
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| 23 | return $this->_write($file, serialize($def), $config);  | 
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| 24 | }  | 
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| 25 | |||
| 26 | /**  | 
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| 27 | * @param HTMLPurifier_Definition $def  | 
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| 28 | * @param HTMLPurifier_Config $config  | 
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| 29 | * @return int|bool  | 
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| 30 | */  | 
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| 31 | public function set($def, $config)  | 
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| 42 | |||
| 43 | /**  | 
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| 44 | * @param HTMLPurifier_Definition $def  | 
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| 45 | * @param HTMLPurifier_Config $config  | 
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| 46 | * @return int|bool  | 
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| 47 | */  | 
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| 48 | public function replace($def, $config)  | 
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| 49 |     { | 
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| 50 |         if (!$this->checkDefType($def)) { | 
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| 51 | return;  | 
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| 52 | }  | 
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| 53 | $file = $this->generateFilePath($config);  | 
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| 54 |         if (!file_exists($file)) { | 
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| 55 | return false;  | 
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| 56 | }  | 
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| 57 |         if (!$this->_prepareDir($config)) { | 
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| 58 | return false;  | 
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| 59 | }  | 
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| 60 | return $this->_write($file, serialize($def), $config);  | 
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| 61 | }  | 
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| 62 | |||
| 63 | /**  | 
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| 64 | * @param HTMLPurifier_Config $config  | 
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| 65 | * @return bool|HTMLPurifier_Config  | 
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| 66 | */  | 
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| 67 | public function get($config)  | 
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| 75 | |||
| 76 | /**  | 
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| 77 | * @param HTMLPurifier_Config $config  | 
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| 78 | * @return bool  | 
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| 79 | */  | 
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| 80 | public function remove($config)  | 
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| 88 | |||
| 89 | /**  | 
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| 90 | * @param HTMLPurifier_Config $config  | 
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| 91 | * @return bool  | 
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| 92 | */  | 
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| 93 | public function flush($config)  | 
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| 118 | |||
| 119 | /**  | 
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| 120 | * @param HTMLPurifier_Config $config  | 
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| 121 | * @return bool  | 
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| 122 | */  | 
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| 123 | public function cleanup($config)  | 
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| 149 | |||
| 150 | /**  | 
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| 151 | * Generates the file path to the serial file corresponding to  | 
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| 152 | * the configuration and definition name  | 
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| 153 | * @param HTMLPurifier_Config $config  | 
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| 154 | * @return string  | 
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| 155 | * @todo Make protected  | 
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| 156 | */  | 
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| 157 | public function generateFilePath($config)  | 
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| 162 | |||
| 163 | /**  | 
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| 164 | * Generates the path to the directory contain this cache's serial files  | 
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| 165 | * @param HTMLPurifier_Config $config  | 
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| 166 | * @return string  | 
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| 167 | * @note No trailing slash  | 
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| 168 | * @todo Make protected  | 
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| 169 | */  | 
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| 170 | public function generateDirectoryPath($config)  | 
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| 175 | |||
| 176 | /**  | 
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| 177 | * Generates path to base directory that contains all definition type  | 
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| 178 | * serials  | 
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| 179 | * @param HTMLPurifier_Config $config  | 
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| 180 | * @return mixed|string  | 
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| 181 | * @todo Make protected  | 
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| 182 | */  | 
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| 183 | public function generateBaseDirectoryPath($config)  | 
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| 189 | |||
| 190 | /**  | 
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| 191 | * Convenience wrapper function for file_put_contents  | 
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| 192 | * @param string $file File name to write to  | 
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| 193 | * @param string $data Data to write into file  | 
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| 194 | * @param HTMLPurifier_Config $config  | 
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| 195 | * @return int|bool Number of bytes written if success, or false if failure.  | 
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| 196 | */  | 
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| 197 | private function _write($file, $data, $config)  | 
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| 209 | |||
| 210 | /**  | 
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| 211 | * Prepares the directory that this type stores the serials in  | 
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| 212 | * @param HTMLPurifier_Config $config  | 
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| 213 | * @return bool True if successful  | 
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| 214 | */  | 
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| 215 | private function _prepareDir($config)  | 
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| 251 | |||
| 252 | /**  | 
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| 253 | * Tests permissions on a directory and throws out friendly  | 
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| 254 | * error messages and attempts to chmod it itself if possible  | 
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| 255 | * @param string $dir Directory path  | 
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| 256 | * @param int $chmod Permissions  | 
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| 257 | * @return bool True if directory is writable  | 
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| 258 | */  | 
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| 259 | private function _testPermissions($dir, $chmod)  | 
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| 304 | }  | 
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| 305 | |||
| 307 |