Duplicate code is one of the most pungent code smells. A rule that is often used is to re-structure code once it is duplicated in three or more places.
Common duplication problems, and corresponding solutions are:
Complex classes like Punycode 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 Punycode, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 12 | class Punycode |
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| 13 | { |
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| 14 | |||
| 15 | /** |
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| 16 | * Bootstring parameter values |
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| 17 | * |
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| 18 | */ |
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| 19 | const BASE = 36; |
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| 20 | const TMIN = 1; |
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| 21 | const TMAX = 26; |
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| 22 | const SKEW = 38; |
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| 23 | const DAMP = 700; |
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| 24 | const INITIAL_BIAS = 72; |
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| 25 | const INITIAL_N = 128; |
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| 26 | const PREFIX = 'xn--'; |
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| 27 | const DELIMITER = '-'; |
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| 28 | |||
| 29 | /** |
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| 30 | * Encode table |
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| 31 | * |
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| 32 | * @param array |
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| 33 | */ |
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| 34 | protected static $encodeTable = array( |
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| 35 | 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', |
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| 36 | 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', |
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| 37 | 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', |
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| 38 | ); |
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| 39 | |||
| 40 | /** |
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| 41 | * Decode table |
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| 42 | * |
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| 43 | * @param array |
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| 44 | */ |
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| 45 | protected static $decodeTable = array( |
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| 46 | 'a' => 0, 'b' => 1, 'c' => 2, 'd' => 3, 'e' => 4, 'f' => 5, |
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| 47 | 'g' => 6, 'h' => 7, 'i' => 8, 'j' => 9, 'k' => 10, 'l' => 11, |
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| 48 | 'm' => 12, 'n' => 13, 'o' => 14, 'p' => 15, 'q' => 16, 'r' => 17, |
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| 49 | 's' => 18, 't' => 19, 'u' => 20, 'v' => 21, 'w' => 22, 'x' => 23, |
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| 50 | 'y' => 24, 'z' => 25, '0' => 26, '1' => 27, '2' => 28, '3' => 29, |
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| 51 | '4' => 30, '5' => 31, '6' => 32, '7' => 33, '8' => 34, '9' => 35 |
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| 52 | ); |
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| 53 | |||
| 54 | /** |
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| 55 | * Character encoding |
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| 56 | * |
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| 57 | * @param string |
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| 58 | */ |
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| 59 | protected $encoding; |
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| 60 | |||
| 61 | /** |
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| 62 | * Constructor |
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| 63 | * |
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| 64 | * @param string $encoding Character encoding |
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| 65 | */ |
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| 66 | public function __construct($encoding = 'UTF-8') |
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| 70 | |||
| 71 | /** |
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| 72 | * Encode a domain to its Punycode version |
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| 73 | * |
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| 74 | * @param string $input Domain name in Unicode to be encoded |
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| 75 | * @return string Punycode representation in ASCII |
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| 76 | */ |
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| 77 | public function encode($input) |
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| 96 | |||
| 97 | /** |
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| 98 | * Encode a part of a domain name, such as tld, to its Punycode version |
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| 99 | * |
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| 100 | * @param string $input Part of a domain name |
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| 101 | * @return string Punycode representation of a domain part |
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| 102 | */ |
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| 103 | protected function encodePart($input) |
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| 169 | |||
| 170 | /** |
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| 171 | * Decode a Punycode domain name to its Unicode counterpart |
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| 172 | * |
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| 173 | * @param string $input Domain name in Punycode |
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| 174 | * @return string Unicode domain name |
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| 175 | */ |
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| 176 | public function decode($input) |
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| 200 | |||
| 201 | /** |
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| 202 | * Decode a part of domain name, such as tld |
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| 203 | * |
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| 204 | * @param string $input Part of a domain name |
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| 205 | * @return string Unicode domain part |
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| 206 | */ |
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| 207 | protected function decodePart($input) |
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| 249 | |||
| 250 | /** |
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| 251 | * Calculate the bias threshold to fall between TMIN and TMAX |
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| 252 | * |
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| 253 | * @param integer $k |
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| 254 | * @param integer $bias |
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| 255 | * @return integer |
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| 256 | */ |
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| 257 | protected function calculateThreshold($k, $bias) |
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| 266 | |||
| 267 | /** |
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| 268 | * Bias adaptation |
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| 269 | * |
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| 270 | * @param integer $delta |
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| 271 | * @param integer $numPoints |
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| 272 | * @param boolean $firstTime |
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| 273 | * @return integer |
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| 274 | */ |
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| 275 | protected function adapt($delta, $numPoints, $firstTime) |
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| 293 | |||
| 294 | /** |
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| 295 | * List code points for a given input |
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| 296 | * |
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| 297 | * @param string $input |
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| 298 | * @return array Multi-dimension array with basic, non-basic and aggregated code points |
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| 299 | */ |
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| 300 | protected function listCodePoints($input) |
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| 321 | |||
| 322 | /** |
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| 323 | * Convert a single or multi-byte character to its code point |
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| 324 | * |
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| 325 | * @param string $char |
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| 326 | * @return integer |
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| 327 | */ |
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| 328 | protected function charToCodePoint($char) |
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| 341 | |||
| 342 | /** |
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| 343 | * Convert a code point to its single or multi-byte character |
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| 344 | * |
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| 345 | * @param integer $code |
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| 346 | * @return string |
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| 347 | */ |
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| 348 | protected function codePointToChar($code) |
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| 360 | } |
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| 361 |
Short variable names may make your code harder to understand. Variable names should be self-descriptive. This check looks for variable names who are shorter than a configured minimum.