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 StreamProviderWrapper 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 StreamProviderWrapper, and based on these observations, apply Extract Interface, too.
1 | <?php |
||
17 | class StreamProviderWrapper |
||
18 | { |
||
19 | /** |
||
20 | * Holds reference to the data service instance. |
||
21 | * |
||
22 | * @var IService |
||
23 | */ |
||
24 | private $_service; |
||
25 | |||
26 | /** |
||
27 | * Holds reference to the implementation of IStreamProvider or IStreamProvider2. |
||
28 | * |
||
29 | * |
||
30 | * @var IStreamProvider|IStreamProvider2 |
||
31 | */ |
||
32 | private $_streamProvider; |
||
33 | |||
34 | /** |
||
35 | * Used to check whether interface implementation modified response content type header or not. |
||
36 | * |
||
37 | * |
||
38 | * @var string|null |
||
39 | */ |
||
40 | private $_responseContentType; |
||
41 | |||
42 | /** |
||
43 | * Used to check whether interface implementation modified ETag header or not. |
||
44 | * |
||
45 | * @var string|null |
||
46 | */ |
||
47 | private $_responseETag; |
||
48 | |||
49 | /** |
||
50 | * To set reference to the data service instance. |
||
51 | * |
||
52 | * @param IService $service The data service instance |
||
53 | */ |
||
54 | public function setService(IService $service) |
||
58 | |||
59 | /** |
||
60 | * To get stream associated with the given media resource. |
||
61 | * |
||
62 | * @param object $entity The media resource |
||
63 | * @param ResourceStreamInfo $resourceStreamInfo This will be null if media |
||
64 | * resource is MLE, if media |
||
65 | * resource is named |
||
66 | * stream then will be the |
||
67 | * ResourceStreamInfo instance |
||
68 | * holding the details of |
||
69 | * named stream |
||
70 | * |
||
71 | * @return string|null |
||
72 | */ |
||
73 | public function getReadStream($entity, $resourceStreamInfo) |
||
130 | |||
131 | /** |
||
132 | * Gets the IANA content type (aka media type) of the stream associated with |
||
133 | * the specified media resource. |
||
134 | * |
||
135 | * @param object $entity The entity instance |
||
136 | * (media resource) associated with |
||
137 | * the stream for which the content |
||
138 | * type is to be obtained |
||
139 | * @param ResourceStreamInfo $resourceStreamInfo This will be null if |
||
140 | * media resource is MLE, |
||
141 | * if media resource is named |
||
142 | * stream then will be the |
||
143 | * ResourceStreamInfo instance |
||
144 | * holding the details of |
||
145 | * named stream |
||
146 | * |
||
147 | * @return string|null |
||
148 | */ |
||
149 | View Code Duplication | public function getStreamContentType($entity, $resourceStreamInfo) |
|
150 | { |
||
151 | $contentType = null; |
||
152 | $this->_saveContentTypeAndETag(); |
||
153 | $opContext = $this->_service->getOperationContext(); |
||
154 | if (is_null($resourceStreamInfo)) { |
||
155 | $this->_loadAndValidateStreamProvider(); |
||
156 | $contentType = $this->_streamProvider->getStreamContentType($entity, $opContext); |
||
157 | if (is_null($contentType)) { |
||
158 | throw new InvalidOperationException( |
||
159 | Messages::streamProviderWrapperGetStreamContentTypeReturnsEmptyOrNull() |
||
160 | ); |
||
161 | } |
||
162 | } else { |
||
163 | $this->_loadAndValidateStreamProvider2(); |
||
164 | assert($this->_streamProvider instanceof IStreamProvider2); |
||
165 | $contentType = $this->_streamProvider->getStreamContentType2($entity, $resourceStreamInfo, $opContext); |
||
166 | } |
||
167 | |||
168 | $this->_verifyContentTypeOrETagModified('IDSSP::getStreamContentType'); |
||
169 | |||
170 | return $contentType; |
||
171 | } |
||
172 | |||
173 | /** |
||
174 | * Get the ETag of the stream associated with the entity specified. |
||
175 | * |
||
176 | * @param object $entity The entity instance |
||
177 | * (media resource) associated |
||
178 | * with the stream for which |
||
179 | * the etag is to be obtained |
||
180 | * @param ResourceStreamInfo $resourceStreamInfo This will be null if |
||
181 | * media resource is MLE, |
||
182 | * if media resource is named |
||
183 | * stream then will be the |
||
184 | * ResourceStreamInfo |
||
185 | * instance holding the |
||
186 | * details of named stream |
||
187 | * |
||
188 | * @throws InvalidOperationException |
||
189 | * |
||
190 | * @return string Etag |
||
191 | */ |
||
192 | View Code Duplication | public function getStreamETag($entity, $resourceStreamInfo) |
|
193 | { |
||
194 | $eTag = null; |
||
195 | $this->_saveContentTypeAndETag(); |
||
196 | $opContext = $this->_service->getOperationContext(); |
||
197 | if (is_null($resourceStreamInfo)) { |
||
198 | $this->_loadAndValidateStreamProvider(); |
||
199 | $eTag = $this->_streamProvider->getStreamETag($entity, $opContext); |
||
200 | } else { |
||
201 | $this->_loadAndValidateStreamProvider2(); |
||
202 | assert($this->_streamProvider instanceof IStreamProvider2); |
||
203 | $eTag = $this->_streamProvider->getStreamETag2($entity, $resourceStreamInfo, $opContext); |
||
204 | } |
||
205 | |||
206 | $this->_verifyContentTypeOrETagModified('IDSSP::getStreamETag'); |
||
207 | if (!self::isETagValueValid($eTag, true)) { |
||
208 | throw new InvalidOperationException( |
||
209 | Messages::streamProviderWrapperGetStreamETagReturnedInvalidETagFormat() |
||
210 | ); |
||
211 | } |
||
212 | |||
213 | return $eTag; |
||
214 | } |
||
215 | |||
216 | /** |
||
217 | * Gets the URI clients should use when making retrieve (ie. GET) requests |
||
218 | * to the stream. |
||
219 | * |
||
220 | * @param object $entity The entity instance |
||
221 | * associated with the |
||
222 | * stream for which a |
||
223 | * read stream URI is to |
||
224 | * be obtained |
||
225 | * @param ResourceStreamInfo $resourceStreamInfo This will be null |
||
226 | * if media resource |
||
227 | * is MLE, if media |
||
228 | * resource is named |
||
229 | * stream then will be |
||
230 | * the ResourceStreamInfo |
||
231 | * instance holding the |
||
232 | * details of named stream |
||
233 | * @param string $mediaLinkEntryUri MLE uri |
||
234 | * |
||
235 | * @return string |
||
236 | * |
||
237 | * @throws InvalidOperationException |
||
238 | */ |
||
239 | public function getReadStreamUri( |
||
240 | $entity, |
||
241 | $resourceStreamInfo, |
||
242 | $mediaLinkEntryUri |
||
243 | ) { |
||
244 | $readStreamUri = null; |
||
245 | $this->_saveContentTypeAndETag(); |
||
246 | $opContext = $this->_service->getOperationContext(); |
||
247 | if (is_null($resourceStreamInfo)) { |
||
248 | $this->_loadAndValidateStreamProvider(); |
||
249 | $readStreamUri = $this->_streamProvider->getReadStreamUri($entity, $opContext); |
||
250 | } else { |
||
251 | $this->_loadAndValidateStreamProvider2(); |
||
252 | assert($this->_streamProvider instanceof IStreamProvider2); |
||
253 | $readStreamUri = $this->_streamProvider->getReadStreamUri2($entity, $resourceStreamInfo, $opContext); |
||
254 | } |
||
255 | |||
256 | $this->_verifyContentTypeOrETagModified('IDSSP::getReadStreamUri'); |
||
257 | if (!is_null($readStreamUri)) { |
||
258 | try { |
||
259 | new \POData\Common\Url($readStreamUri); |
||
260 | } catch (\POData\Common\UrlFormatException $ex) { |
||
261 | throw new InvalidOperationException( |
||
262 | Messages::streamProviderWrapperGetReadStreamUriMustReturnAbsoluteUriOrNull() |
||
263 | ); |
||
264 | } |
||
265 | } else { |
||
266 | if (is_null($resourceStreamInfo)) { |
||
267 | // For MLEs the content src attribute is |
||
268 | //required so we cannot return null. |
||
269 | $readStreamUri = $this->getDefaultStreamEditMediaUri($mediaLinkEntryUri, null); |
||
270 | } |
||
271 | } |
||
272 | |||
273 | // Note if readStreamUri is null, the self link for the |
||
274 | // named stream will be omitted. |
||
275 | return $readStreamUri; |
||
276 | } |
||
277 | |||
278 | /** |
||
279 | * Checks the given value is a valid eTag. |
||
280 | * |
||
281 | * @param string $etag eTag to validate |
||
282 | * @param bool $allowStrongEtag True if strong eTag is allowed |
||
283 | * False otherwise |
||
284 | * |
||
285 | * @return bool |
||
286 | */ |
||
287 | public static function isETagValueValid($etag, $allowStrongEtag) |
||
321 | |||
322 | /** |
||
323 | * Get ETag header value from request header. |
||
324 | * |
||
325 | * @param mixed &$eTag On return, this parameter will hold |
||
326 | * value of IfMatch or IfNoneMatch |
||
327 | * header, if this header is absent then |
||
328 | * this parameter will hold NULL |
||
329 | * @param mixed &$checkETagForEquality On return, this parameter will hold |
||
330 | * true if IfMatch is present, false if |
||
331 | * IfNoneMatch header is present, null |
||
332 | * otherwise |
||
333 | */ |
||
334 | private function _getETagFromHeaders(&$eTag, &$checkETagForEquality) |
||
355 | |||
356 | /** |
||
357 | * Validates that an implementation of IStreamProvider exists and |
||
358 | * load it. |
||
359 | * |
||
360 | * |
||
361 | * @throws ODataException |
||
362 | */ |
||
363 | private function _loadAndValidateStreamProvider() |
||
375 | |||
376 | /** |
||
377 | * Validates that an implementation of IStreamProvider2 exists and |
||
378 | * load it. |
||
379 | * |
||
380 | * |
||
381 | * @throws ODataException |
||
382 | */ |
||
383 | private function _loadAndValidateStreamProvider2() |
||
405 | |||
406 | /** |
||
407 | * Ask data service to load stream provider instance. |
||
408 | * |
||
409 | * |
||
410 | * @throws ODataException |
||
411 | */ |
||
412 | private function _loadStreamProvider() |
||
423 | |||
424 | /** |
||
425 | * Construct the default edit media uri from the given media link entry uri. |
||
426 | * |
||
427 | * @param string $mediaLinkEntryUri Uri to the media link entry |
||
428 | * @param ResourceStreamInfo|null $resourceStreamInfo Stream info instance, if its |
||
429 | * null default stream is assumed |
||
430 | * |
||
431 | * @return string Uri to the media resource |
||
432 | */ |
||
433 | public function getDefaultStreamEditMediaUri($mediaLinkEntryUri, $resourceStreamInfo) |
||
440 | |||
441 | /** |
||
442 | * Save value of content type and etag headers before invoking implementor |
||
443 | * methods. |
||
444 | */ |
||
445 | private function _saveContentTypeAndETag() |
||
450 | |||
451 | /** |
||
452 | * Check whether implementor modified content type or etag header |
||
453 | * if so throw InvalidOperationException. |
||
454 | * |
||
455 | * @param string $methodName NAme of the method |
||
456 | * |
||
457 | * @throws InvalidOperationException |
||
458 | */ |
||
459 | private function _verifyContentTypeOrETagModified($methodName) |
||
469 | } |
||
470 |
It seems like the method you are trying to call exists only in some of the possible types.
Let’s take a look at an example:
Available Fixes
Add an additional type-check:
Only allow a single type to be passed if the variable comes from a parameter: