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 IRI 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 IRI, and based on these observations, apply Extract Interface, too.
| 1 | <?php  | 
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| 19 | class IRI  | 
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| 20 | { | 
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| 21 | /**  | 
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| 22 | * The scheme  | 
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| 23 | *  | 
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| 24 | * @var string|null  | 
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| 25 | */  | 
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| 26 | private $scheme = null;  | 
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| 27 | |||
| 28 | /**  | 
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| 29 | * The user information  | 
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| 30 | *  | 
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| 31 | * @var string|null  | 
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| 32 | */  | 
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| 33 | private $userinfo = null;  | 
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| 34 | |||
| 35 | /**  | 
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| 36 | * The host  | 
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| 37 | *  | 
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| 38 | * @var string|null  | 
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| 39 | */  | 
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| 40 | private $host = null;  | 
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| 41 | |||
| 42 | /**  | 
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| 43 | * The port  | 
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| 44 | *  | 
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| 45 | * @var string|null  | 
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| 46 | */  | 
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| 47 | private $port = null;  | 
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| 48 | |||
| 49 | /**  | 
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| 50 | * The path  | 
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| 51 | *  | 
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| 52 | * @var string  | 
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| 53 | */  | 
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| 54 | private $path = '';  | 
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| 55 | |||
| 56 | /**  | 
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| 57 | * The query component  | 
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| 58 | *  | 
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| 59 | * @var string|null  | 
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| 60 | */  | 
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| 61 | private $query = null;  | 
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| 62 | |||
| 63 | /**  | 
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| 64 | * The fragment identifier  | 
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| 65 | *  | 
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| 66 | * @var string|null  | 
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| 67 | */  | 
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| 68 | private $fragment = null;  | 
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| 69 | |||
| 70 | |||
| 71 | /**  | 
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| 72 | * Constructor  | 
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| 73 | *  | 
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| 74 | * @param null|string|IRI $iri The IRI.  | 
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| 75 | *  | 
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| 76 | * @throws \InvalidArgumentException If an invalid IRI is passed.  | 
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| 77 | *  | 
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| 78 | * @api  | 
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| 79 | */  | 
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| 80 | public function __construct($iri = null)  | 
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| 101 | |||
| 102 | /**  | 
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| 103 | * Get the scheme  | 
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| 104 | *  | 
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| 105 | * @return string|null Returns the scheme or null if not set.  | 
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| 106 | */  | 
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| 107 | public function getScheme()  | 
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| 111 | |||
| 112 | /**  | 
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| 113 | * Get the authority  | 
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| 114 | *  | 
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| 115 | * @return string|null Returns the authority or null if not set.  | 
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| 116 | */  | 
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| 117 | public function getAuthority()  | 
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| 134 | |||
| 135 | /**  | 
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| 136 | * Get the user information  | 
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| 137 | *  | 
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| 138 | * @return string|null Returns the user information or null if not set.  | 
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| 139 | */  | 
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| 140 | public function getUserInfo()  | 
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| 144 | |||
| 145 | /**  | 
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| 146 | * Get the host  | 
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| 147 | *  | 
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| 148 | * @return string|null Returns the host or null if not set.  | 
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| 149 | */  | 
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| 150 | public function getHost()  | 
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| 154 | |||
| 155 | /**  | 
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| 156 | * Get the port  | 
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| 157 | *  | 
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| 158 | * @return string|null Returns the port or null if not set.  | 
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| 159 | */  | 
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| 160 | public function getPort()  | 
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| 164 | |||
| 165 | /**  | 
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| 166 | * Get the path  | 
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| 167 | *  | 
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| 168 | * @return string Returns the path which might be empty.  | 
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| 169 | */  | 
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| 170 | public function getPath()  | 
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| 174 | |||
| 175 | /**  | 
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| 176 | * Get the query component  | 
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| 177 | *  | 
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| 178 | * @return string|null Returns the query component or null if not set.  | 
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| 179 | */  | 
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| 180 | public function getQuery()  | 
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| 184 | |||
| 185 | /**  | 
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| 186 | * Get the fragment identifier  | 
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| 187 | *  | 
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| 188 | * @return string|null Returns the fragment identifier or null if not set.  | 
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| 189 | */  | 
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| 190 | public function getFragment()  | 
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| 194 | |||
| 195 | /**  | 
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| 196 | * Find out whether the IRI is absolute  | 
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| 197 | *  | 
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| 198 | * @return bool Returns true if the IRI is absolute, false otherwise.  | 
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| 199 | *  | 
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| 200 | * @api  | 
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| 201 | */  | 
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| 202 | public function isAbsolute()  | 
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| 206 | |||
| 207 | /**  | 
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| 208 | * Get as absolute IRI, i.e., without fragment identifier  | 
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| 209 | *  | 
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| 210 | * @return IRI The absolute IRI, i.e., without fragment identifier  | 
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| 211 | *  | 
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| 212 | * @throws \UnexpectedValueException If the IRI is a relative IRI.  | 
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| 213 | *  | 
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| 214 | * @link http://tools.ietf.org/html/rfc3987#section-2.2 RFC3987 absolute-IRI  | 
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| 215 | *  | 
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| 216 | * @api  | 
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| 217 | */  | 
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| 218 | public function getAbsoluteIri()  | 
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| 229 | |||
| 230 | /**  | 
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| 231 | * Check whether the passed IRI is equal  | 
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| 232 | *  | 
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| 233 | * @param IRI|string $iri IRI to compare to this instance.  | 
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| 234 | *  | 
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| 235 | * @return bool Returns true if the two IRIs are equal, false otherwise.  | 
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| 236 | *  | 
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| 237 | * @api  | 
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| 238 | */  | 
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| 239 | public function equals($iri)  | 
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| 244 | |||
| 245 | /**  | 
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| 246 | * Resolve a (relative) IRI reference against this IRI  | 
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| 247 | *  | 
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| 248 | * @param IRI|string $reference The (relative) IRI reference that should  | 
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| 249 | * be resolved against this IRI.  | 
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| 250 | *  | 
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| 251 | * @return IRI The resolved IRI.  | 
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| 252 | *  | 
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| 253 | * @throws \InvalidArgumentException If an invalid IRI is passed.  | 
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| 254 | *  | 
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| 255 | * @link http://tools.ietf.org/html/rfc3986#section-5.2  | 
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| 256 | *  | 
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| 257 | * @api  | 
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| 258 | */  | 
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| 259 | public function resolve($reference)  | 
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| 339 | |||
| 340 | /**  | 
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| 341 | * Transform this IRI to a IRI reference relative to the passed base IRI  | 
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| 342 | *  | 
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| 343 | * @param IRI|string $base The (relative) IRI reference that should be  | 
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| 344 | * be used as base IRI.  | 
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| 345 | * @param bool Defines whether schema-relative IRIs such  | 
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| 346 | * as `//example.com` should be created (`true`)  | 
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| 347 | * or not (`false`).  | 
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| 348 | *  | 
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| 349 | * @return IRI The IRI reference relative to the passed base IRI.  | 
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| 350 | *  | 
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| 351 | * @throws \InvalidArgumentException If an invalid IRI is passed.  | 
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| 352 | *  | 
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| 353 | * @api  | 
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| 354 | */  | 
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| 355 | public function relativeTo($base, $schemaRelative = false)  | 
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| 427 | |||
| 428 | /**  | 
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| 429 | * Convert an IRI to a relative IRI reference using this IRI as base  | 
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| 430 | *  | 
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| 431 | * This method provides a more convenient interface than the  | 
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| 432 |      * {@link IRI::relativeTo()} method if the base IRI stays the same while | 
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| 433 | * the IRIs to convert to relative IRI references change.  | 
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| 434 | *  | 
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| 435 | * @param string|IRI $iri The IRI to convert to a relative reference  | 
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| 436 | * @param bool Defines whether schema-relative IRIs such  | 
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| 437 | * as `//example.com` should be created (`true`)  | 
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| 438 | * or not (`false`).  | 
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| 439 | *  | 
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| 440 | * @throws \InvalidArgumentException If an invalid IRI is passed.  | 
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| 441 | *  | 
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| 442 | * @see \ML\IRI\IRI::relativeTo()  | 
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| 443 | *  | 
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| 444 | * @return IRI The relative IRI reference  | 
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| 445 | */  | 
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| 446 | public function baseFor($iri, $schemaRelative = false)  | 
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| 454 | |||
| 455 | /**  | 
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| 456 | * Get a string representation of this IRI object  | 
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| 457 | *  | 
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| 458 | * @return string A string representation of this IRI instance.  | 
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| 459 | *  | 
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| 460 | * @api  | 
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| 461 | */  | 
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| 462 | public function __toString()  | 
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| 486 | |||
| 487 | /**  | 
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| 488 | * Parse an IRI into it's components  | 
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| 489 | *  | 
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| 490 | * This is done according to  | 
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| 491 |      * {@link http://tools.ietf.org/html/rfc3986#section-3.1 RFC3986}. | 
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| 492 | *  | 
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| 493 | * @param string $iri The IRI to parse.  | 
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| 494 | */  | 
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| 495 | protected function parse($iri)  | 
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| 552 | |||
| 553 | /**  | 
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| 554 | * Remove dot-segments  | 
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| 555 | *  | 
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| 556 | * This method removes the special "." and ".." complete path segments  | 
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| 557 | * from an IRI.  | 
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| 558 | *  | 
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| 559 | * @param string $input The IRI from which dot segments should be removed.  | 
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| 560 | *  | 
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| 561 | * @return string The IRI with all dot-segments removed.  | 
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| 562 | *  | 
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| 563 | * @link http://tools.ietf.org/html/rfc3986#section-5.2.4  | 
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| 564 | */  | 
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| 565 | private static function removeDotSegments($input)  | 
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| 602 | }  | 
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| 603 | 
This check looks for variable assignements that are either overwritten by other assignments or where the variable is not used subsequently.
Both the
$myVarassignment in line 1 and the$higherassignment in line 2 are dead. The first because$myVaris never used and the second because$higheris always overwritten for every possible time line.