Complex classes like SeoPage 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 SeoPage, and based on these observations, apply Extract Interface, too.
| 1 | <?php  | 
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| 19 | class SeoPage implements SeoPageInterface, PageWithStructuredData  | 
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| 20 | { | 
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| 21 | /**  | 
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| 22 | * @var string  | 
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| 23 | */  | 
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| 24 | protected $title;  | 
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| 25 | |||
| 26 | /**  | 
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| 27 | * @var array  | 
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| 28 | */  | 
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| 29 | protected $metas;  | 
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| 30 | |||
| 31 | /**  | 
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| 32 | * @var array  | 
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| 33 | */  | 
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| 34 | protected $htmlAttributes;  | 
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| 35 | |||
| 36 | /**  | 
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| 37 | * @var string  | 
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| 38 | */  | 
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| 39 | protected $linkCanonical;  | 
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| 40 | |||
| 41 | /**  | 
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| 42 | * @var string  | 
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| 43 | */  | 
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| 44 | protected $separator;  | 
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| 45 | |||
| 46 | /**  | 
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| 47 | * @var array  | 
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| 48 | */  | 
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| 49 | protected $headAttributes;  | 
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| 50 | |||
| 51 | /**  | 
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| 52 | * @var array  | 
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| 53 | */  | 
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| 54 | protected $langAlternates;  | 
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| 55 | |||
| 56 | /**  | 
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| 57 | * @var array  | 
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| 58 | */  | 
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| 59 | protected $oembedLinks;  | 
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| 60 | |||
| 61 | /**  | 
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| 62 | * A JSON-LD string, which can be served as structured data.  | 
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| 63 | *  | 
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| 64 | * @var string  | 
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| 65 | */  | 
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| 66 | private $structuredData;  | 
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| 67 | |||
| 68 | /**  | 
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| 69 | * @param string $title  | 
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| 70 | */  | 
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| 71 | public function __construct($title = '')  | 
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| 90 | |||
| 91 | /**  | 
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| 92 |      * {@inheritdoc} | 
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| 93 | */  | 
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| 94 | public function setTitle($title)  | 
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| 100 | |||
| 101 | /**  | 
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| 102 |      * {@inheritdoc} | 
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| 103 | */  | 
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| 104 | public function addTitle($title)  | 
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| 110 | |||
| 111 | /**  | 
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| 112 |      * {@inheritdoc} | 
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| 113 | */  | 
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| 114 | public function getTitle()  | 
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| 118 | |||
| 119 | /**  | 
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| 120 |      * {@inheritdoc} | 
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| 121 | */  | 
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| 122 | public function getMetas()  | 
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| 126 | |||
| 127 | /**  | 
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| 128 |      * {@inheritdoc} | 
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| 129 | */  | 
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| 130 | public function addMeta($type, $name, $content, array $extras = [])  | 
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| 140 | |||
| 141 | /**  | 
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| 142 | * @param string $type  | 
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| 143 | * @param string $name  | 
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| 144 | *  | 
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| 145 | * @return bool  | 
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| 146 | */  | 
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| 147 | public function hasMeta($type, $name)  | 
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| 151 | |||
| 152 | /**  | 
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| 153 | * @param string $type  | 
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| 154 | * @param string $name  | 
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| 155 | *  | 
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| 156 | * @return $this  | 
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| 157 | */  | 
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| 158 | public function removeMeta($type, $name)  | 
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| 164 | |||
| 165 | /**  | 
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| 166 |      * {@inheritdoc} | 
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| 167 | */  | 
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| 168 | public function setMetas(array $metadatas)  | 
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| 186 | |||
| 187 | /**  | 
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| 188 |      * {@inheritdoc} | 
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| 189 | */  | 
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| 190 | public function setHtmlAttributes(array $attributes)  | 
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| 196 | |||
| 197 | /**  | 
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| 198 |      * {@inheritdoc} | 
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| 199 | */  | 
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| 200 | public function addHtmlAttributes($name, $value)  | 
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| 206 | |||
| 207 | /**  | 
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| 208 | * @param string $name  | 
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| 209 | *  | 
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| 210 | * @return $this  | 
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| 211 | */  | 
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| 212 | public function removeHtmlAttributes($name)  | 
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| 218 | |||
| 219 | /**  | 
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| 220 |      * {@inheritdoc} | 
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| 221 | */  | 
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| 222 | public function getHtmlAttributes()  | 
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| 226 | |||
| 227 | /**  | 
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| 228 | * @param string $name  | 
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| 229 | *  | 
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| 230 | * @return bool  | 
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| 231 | */  | 
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| 232 | public function hasHtmlAttribute($name)  | 
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| 236 | |||
| 237 | /**  | 
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| 238 | * @param array $attributes  | 
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| 239 | *  | 
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| 240 | * @return SeoPageInterface  | 
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| 241 | */  | 
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| 242 | public function setHeadAttributes(array $attributes)  | 
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| 248 | |||
| 249 | /**  | 
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| 250 | * @param string $name  | 
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| 251 | * @param string $value  | 
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| 252 | *  | 
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| 253 | * @return SeoPageInterface  | 
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| 254 | */  | 
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| 255 | public function addHeadAttribute($name, $value)  | 
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| 261 | |||
| 262 | /**  | 
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| 263 | * @param string $name  | 
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| 264 | *  | 
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| 265 | * @return $this  | 
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| 266 | */  | 
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| 267 | public function removeHeadAttribute($name)  | 
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| 273 | |||
| 274 | /**  | 
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| 275 | * @return array  | 
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| 276 | */  | 
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| 277 | public function getHeadAttributes()  | 
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| 281 | |||
| 282 | /**  | 
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| 283 | * @param string $name  | 
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| 284 | *  | 
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| 285 | * @return array  | 
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| 286 | */  | 
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| 287 | public function hasHeadAttribute($name)  | 
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| 291 | |||
| 292 | /**  | 
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| 293 |      * {@inheritdoc} | 
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| 294 | */  | 
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| 295 | public function setLinkCanonical($link)  | 
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| 301 | |||
| 302 | /**  | 
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| 303 |      * {@inheritdoc} | 
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| 304 | */  | 
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| 305 | public function getLinkCanonical()  | 
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| 309 | |||
| 310 | /**  | 
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| 311 |      * {@inheritdoc} | 
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| 312 | */  | 
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| 313 | public function removeLinkCanonical()  | 
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| 317 | |||
| 318 | /**  | 
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| 319 |      * {@inheritdoc} | 
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| 320 | */  | 
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| 321 | public function setSeparator($separator)  | 
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| 327 | |||
| 328 | /**  | 
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| 329 |      * {@inheritdoc} | 
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| 330 | */  | 
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| 331 | public function setLangAlternates(array $langAlternates)  | 
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| 337 | |||
| 338 | /**  | 
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| 339 |      * {@inheritdoc} | 
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| 340 | */  | 
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| 341 | public function addLangAlternate($href, $hrefLang)  | 
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| 347 | |||
| 348 | /**  | 
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| 349 | * @param string $href  | 
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| 350 | *  | 
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| 351 | * @return $this  | 
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| 352 | */  | 
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| 353 | public function removeLangAlternate($href)  | 
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| 359 | |||
| 360 | /**  | 
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| 361 | * @param string $href  | 
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| 362 | *  | 
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| 363 | * @return $this  | 
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| 364 | */  | 
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| 365 | public function hasLangAlternate($href)  | 
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| 369 | |||
| 370 | /**  | 
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| 371 |      * {@inheritdoc} | 
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| 372 | */  | 
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| 373 | public function getLangAlternates()  | 
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| 377 | |||
| 378 | /**  | 
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| 379 | * @param $title  | 
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| 380 | * @param $link  | 
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| 381 | *  | 
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| 382 | * @return SeoPageInterface  | 
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| 383 | */  | 
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| 384 | public function addOEmbedLink($title, $link)  | 
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| 390 | |||
| 391 | /**  | 
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| 392 | * @return array  | 
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| 393 | */  | 
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| 394 | public function getOEmbedLinks()  | 
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| 398 | |||
| 399 | /**  | 
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| 400 |      * {@inheritdoc} | 
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| 401 | */  | 
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| 402 | public function getStructuredData()  | 
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| 403 |     { | 
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| 404 | return $this->structuredData;  | 
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| 405 | }  | 
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| 406 | |||
| 407 | public function setStructuredData($structuredData)  | 
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| 408 |     { | 
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| 409 | $this->structuredData = $structuredData;  | 
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| 410 | |||
| 411 | return $this;  | 
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| 412 | }  | 
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| 413 | |||
| 414 | /**  | 
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| 415 | * @param mixed $meta  | 
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| 416 | *  | 
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| 417 | * @return array  | 
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| 418 | */  | 
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| 419 | private function normalize($meta)  | 
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| 420 |     { | 
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| 421 |         if (\is_string($meta)) { | 
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| 422 | return [$meta, []];  | 
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| 423 | }  | 
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| 424 | |||
| 425 | return $meta;  | 
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| 426 | }  | 
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| 427 | |||
| 428 | /**  | 
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| 429 | * @param mixed $meta  | 
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| 430 | *  | 
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| 431 | * @return array  | 
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| 432 | */  | 
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| 433 | private function normalize($meta)  | 
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| 441 | }  | 
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| 442 |