Complex classes like MissingSubjectTripleNodeSimplifier 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 MissingSubjectTripleNodeSimplifier, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 31 | class MissingSubjectTripleNodeSimplifier implements NodeSimplifier { |
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| 32 | |||
| 33 | const QUERY_LIMIT = 50; |
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| 34 | |||
| 35 | /** |
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| 36 | * @var NodeSimplifierFactory |
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| 37 | */ |
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| 38 | private $nodeSimplifierFactory; |
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| 39 | |||
| 40 | /** |
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| 41 | * @var EntityStore |
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| 42 | */ |
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| 43 | private $entityStore; |
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| 44 | |||
| 45 | /** |
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| 46 | * @var ResourceListNodeParser |
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| 47 | */ |
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| 48 | private $resourceListNodeParser; |
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| 49 | |||
| 50 | /** |
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| 51 | * @param NodeSimplifierFactory $nodeSimplifierFactory |
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| 52 | * @param EntityStore $entityStore |
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| 53 | * @param ResourceListNodeParser $resourceListNodeParser |
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| 54 | */ |
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| 55 | 22 | public function __construct(NodeSimplifierFactory $nodeSimplifierFactory, EntityStore $entityStore, ResourceListNodeParser $resourceListNodeParser) { |
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| 56 | 22 | $this->nodeSimplifierFactory = $nodeSimplifierFactory; |
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| 57 | 22 | $this->entityStore = $entityStore; |
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| 58 | 22 | $this->resourceListNodeParser = $resourceListNodeParser; |
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| 59 | } |
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| 60 | |||
| 61 | /** |
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| 62 | * @see AbstractNode::isSimplifierFor |
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| 63 | */ |
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| 64 | 5 | public function isSimplifierFor(AbstractNode $node) { |
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| 67 | |||
| 68 | 5 | private function isTripleWithMissingSubject(AbstractNode $node) { |
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| 69 | 5 | return $node instanceof TripleNode && |
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| 70 | 1 | $node->getSubject() instanceof MissingNode; |
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| 71 | 5 | } |
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| 72 | |||
| 73 | 4 | private function isTripleWithMissingSubjectOperator(AbstractNode $node) { |
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| 74 | 3 | if(!($node instanceof IntersectionNode || $node instanceof UnionNode)) { |
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| 75 | 4 | return false; |
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| 76 | } |
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| 77 | |||
| 78 | foreach($node->getOperands() as $operand) { |
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| 79 | if(!$this->isSimplifierFor($operand)) { |
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| 80 | return false; |
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| 81 | } |
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| 82 | } |
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| 83 | |||
| 84 | return true; |
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| 85 | 3 | } |
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| 86 | |||
| 87 | /** |
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| 88 | * @see NodeSimplifier::doSimplification |
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| 89 | */ |
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| 90 | 14 | public function simplify(AbstractNode $node) { |
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| 91 | try { |
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| 92 | 8 | $query = $this->buildQueryForNode($node); |
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| 93 | } catch(EmptyQueryException $e) { |
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| 94 | return new ResourceListNode(); |
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| 95 | 10 | } |
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| 96 | |||
| 97 | $entityIds = $this->entityStore->getItemIdForQueryLookup()->getItemIdsForQuery($query, new QueryOptions(self::QUERY_LIMIT, 0)); |
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| 98 | |||
| 99 | return $this->formatQueryResult($entityIds); |
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| 100 | 14 | } |
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| 101 | |||
| 102 | 12 | private function buildQueryForNode(AbstractNode $node) { |
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| 113 | |||
| 114 | 5 | private function buildQueryForUnion(UnionNode $unionNode) { |
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| 115 | 5 | $queries = array(); |
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| 116 | |||
| 117 | 5 | foreach($unionNode->getOperands() as $operandNode) { |
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| 134 | |||
| 135 | 3 | private function buildQueryForIntersection(IntersectionNode $intersectionNode) { |
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| 149 | |||
| 150 | 11 | private function buildQueryForTriple(TripleNode $triple) { |
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| 186 | |||
| 187 | 8 | private function bagsPropertiesPerType($propertyNodes) { |
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| 200 | |||
| 201 | 4 | private function buildQueryForProperty(WikibaseResourceNode $predicate, ResourceListNode $objectList) { |
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| 207 | |||
| 208 | 4 | private function buildValueDescriptionsForObjects(ResourceListNode $objectList) { |
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| 225 | |||
| 226 | 6 | private function formatQueryResult(array $subjectIds) { |
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| 235 | } |
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| 236 |
Let’s take a look at an example:
In the above example, the authenticate() method works fine as long as you just pass instances of MyUser. However, if you now also want to pass a different implementation of User which does not have a getDisplayName() method, the code will break.
Available Fixes
Change the type-hint for the parameter:
Add an additional type-check:
Add the method to the interface: