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<?php |
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namespace VDB\Spider\Discoverer; |
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use VDB\Spider\Resource; |
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use VDB\Spider\Filter\PreFetchFilterInterface; |
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use VDB\Spider\Uri\DiscoveredUri; |
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class DiscovererSet |
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{ |
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/** |
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* @var Discoverer[] |
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*/ |
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private $discoverers = array(); |
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/** @var Filter[] */ |
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private $filters = array(); |
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/** |
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* @var int maximum crawl depth |
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*/ |
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public $maxDepth = 3; |
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/** |
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* @var array the list of already visited URIs with the depth they were discovered on as value |
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*/ |
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private $alreadySeenUris = array(); |
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public function __construct(array $discoverers = array()) |
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{ |
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foreach ($discoverers as $alias => $discoverer) { |
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$this->set($discoverer, is_int($alias) ? null : $alias); |
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} |
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} |
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/** |
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* @param DiscoveredUri $uri |
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* |
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* Mark an Uri as already seen. |
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* |
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* If it already exists, it is not overwritten, since we want to keep the |
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* first depth it was found at. |
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*/ |
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private function markSeen(DiscoveredUri $uri) |
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{ |
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$uriString = $uri->normalize()->toString(); |
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if (!array_key_exists($uriString, $this->alreadySeenUris)) { |
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$this->alreadySeenUris[$uriString] = $uri->getDepthFound(); |
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} |
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} |
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/** |
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* @return bool Returns true if this URI was found at max depth |
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*/ |
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private function isAtMaxDepth(DiscoveredUri $uri) |
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{ |
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return $uri->getDepthFound() === $this->maxDepth; |
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} |
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/** |
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* @param Resource $resource |
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* @return UriInterface[] |
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*/ |
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public function discover(Resource $resource) |
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{ |
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$this->markSeen($resource->getUri()); |
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if ($this->isAtMaxDepth($resource->getUri())) { |
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return []; |
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} |
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$discoveredUris = []; |
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foreach ($this->discoverers as $discoverer) { |
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$discoveredUris = array_merge($discoveredUris, $discoverer->discover($resource)); |
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} |
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$this->normalize($discoveredUris); |
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$this->removeDuplicates($discoveredUris); |
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$this->filterAlreadySeen($discoveredUris); |
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$this->filter($discoveredUris); |
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foreach ($discoveredUris as $uri) { |
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$uri->setDepthFound($resource->getUri()->getDepthFound() + 1); |
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$this->markSeen($uri); |
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} |
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return $discoveredUris; |
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} |
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/** |
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* Sets a discoverer. |
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* |
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* @param discovererInterface $discoverer The discoverer instance |
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* @param string|null $alias An alias |
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*/ |
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public function set(DiscovererInterface $discoverer, $alias = null) |
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{ |
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$this->discoverers[$discoverer->getName()] = $discoverer; |
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if (null !== $alias) { |
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$this->discoverers[$alias] = $discoverer; |
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} |
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} |
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/** |
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* @param PreFetchFilterInterface $filter |
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*/ |
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public function addFilter(PreFetchFilterInterface $filter) |
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{ |
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$this->filters[] = $filter; |
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} |
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/** |
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* @param UriInterface[] $discoveredUris |
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*/ |
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private function normalize(array &$discoveredUris) |
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{ |
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foreach ($discoveredUris as &$uri) { |
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$uri->normalize(); |
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} |
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} |
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/** |
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* @param UriInterface[] $discoveredUris |
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*/ |
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private function filterAlreadySeen(array &$discoveredUris) |
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{ |
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foreach ($discoveredUris as $k => &$uri) { |
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if (array_key_exists($uri->toString(), $this->alreadySeenUris)) { |
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unset($discoveredUris[$k]); |
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} |
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} |
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} |
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/** |
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* @param UriInterface[] $discoveredUris |
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*/ |
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private function filter(array &$discoveredUris) |
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{ |
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foreach ($discoveredUris as $k => &$uri) { |
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foreach ($this->filters as $filter) { |
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if ($filter->match($uri)) { |
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unset($discoveredUris[$k]); |
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} |
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} |
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} |
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} |
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/** |
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* @param UriInterface[] $discoveredUris |
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*/ |
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private function removeDuplicates(array &$discoveredUris) |
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{ |
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// make sure there are no duplicates in the list |
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$tmp = array(); |
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/** @var Uri $uri */ |
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foreach ($discoveredUris as $k => $uri) { |
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$tmp[$k] = $uri->toString(); |
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} |
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// Find duplicates in temporary array |
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$tmp = array_unique($tmp); |
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// Remove the duplicates from original array |
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foreach ($discoveredUris as $k => $uri) { |
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if (!array_key_exists($k, $tmp)) { |
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unset($discoveredUris[$k]); |
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} |
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} |
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} |
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} |
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