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 XmlLocation 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 XmlLocation, and based on these observations, apply Extract Interface, too.
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13 | class XmlLocation extends AbstractLocation |
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14 | { |
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15 | /** @var \XMLWriter XML writer resource */ |
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16 | private $writer; |
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17 | |||
18 | /** @var string Content-Type header added when XML is found */ |
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19 | private $contentType; |
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20 | |||
21 | /** @var Parameter[] Buffered elements to write */ |
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22 | private $buffered = []; |
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23 | |||
24 | /** |
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25 | * @param string $locationName Name of the location |
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26 | * @param string $contentType Set to a non-empty string to add a |
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27 | * Content-Type header to a request if any XML content is added to the |
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28 | * body. Pass an empty string to disable the addition of the header. |
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29 | */ |
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30 | 4 | public function __construct($locationName = 'xml', $contentType = 'application/xml') |
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35 | |||
36 | /** |
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37 | * @param CommandInterface $command |
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38 | * @param RequestInterface $request |
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39 | * @param Parameter $param |
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40 | * |
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41 | * @return RequestInterface |
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42 | */ |
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43 | 17 | public function visit( |
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59 | |||
60 | /** |
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61 | * @param CommandInterface $command |
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62 | * @param RequestInterface $request |
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63 | * @param Operation $operation |
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64 | * |
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65 | * @return RequestInterface |
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66 | */ |
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67 | 18 | public function after( |
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115 | |||
116 | /** |
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117 | * Create the root XML element to use with a request |
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118 | * |
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119 | * @param Operation $operation Operation object |
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120 | * |
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121 | * @return \XMLWriter |
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122 | */ |
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123 | 18 | protected function createRootElement(Operation $operation) |
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147 | |||
148 | /** |
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149 | * Recursively build the XML body |
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150 | * |
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151 | * @param \XMLWriter $writer XML to modify |
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152 | * @param Parameter $param API Parameter |
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153 | * @param mixed $value Value to add |
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154 | */ |
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155 | 17 | protected function addXml(\XMLWriter $writer, Parameter $param, $value) |
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190 | |||
191 | /** |
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192 | * Write an attribute with namespace if used |
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193 | * |
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194 | * @param \XMLWriter $writer XMLWriter instance |
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195 | * @param string $prefix Namespace prefix if any |
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196 | * @param string $name Attribute name |
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197 | * @param string $namespace The uri of the namespace |
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198 | * @param string $value The attribute content |
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199 | */ |
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200 | 5 | protected function writeAttribute($writer, $prefix, $name, $namespace, $value) |
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208 | |||
209 | /** |
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210 | * Write an element with namespace if used |
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211 | * |
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212 | * @param \XMLWriter $writer XML writer resource |
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213 | * @param string $prefix Namespace prefix if any |
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214 | * @param string $name Element name |
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215 | * @param string $namespace The uri of the namespace |
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216 | * @param string $value The element content |
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217 | */ |
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218 | 15 | protected function writeElement(\XMLWriter $writer, $prefix, $name, $namespace, $value) |
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232 | |||
233 | /** |
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234 | * Create a new xml writer and start a document |
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235 | * |
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236 | * @param string $encoding document encoding |
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237 | * |
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238 | * @return \XMLWriter the writer resource |
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239 | * @throws \RuntimeException if the document cannot be started |
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240 | */ |
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241 | 18 | protected function startDocument($encoding) |
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253 | |||
254 | /** |
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255 | * End the document and return the output |
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256 | * |
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257 | * @param \XMLWriter $writer |
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258 | * |
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259 | * @return string the writer resource |
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260 | */ |
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261 | 18 | protected function finishDocument($writer) |
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267 | |||
268 | /** |
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269 | * Add an array to the XML |
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270 | * |
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271 | * @param \XMLWriter $writer |
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272 | * @param Parameter $param |
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273 | * @param $value |
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274 | */ |
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275 | 4 | protected function addXmlArray(\XMLWriter $writer, Parameter $param, &$value) |
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283 | |||
284 | /** |
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285 | * Add an object to the XML |
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286 | * |
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287 | * @param \XMLWriter $writer |
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288 | * @param Parameter $param |
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289 | * @param $value |
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290 | */ |
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291 | 8 | protected function addXmlObject(\XMLWriter $writer, Parameter $param, &$value) |
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311 | |||
312 | /** |
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313 | * @param $value |
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314 | * @param Parameter $param |
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315 | * @param Operation $operation |
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316 | */ |
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317 | 17 | private function visitWithValue( |
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328 | } |
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329 |