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diff --git a/www/wiki/extensions/SemanticMediaWiki/src/SQLStore/QueryEngine/README.md b/www/wiki/extensions/SemanticMediaWiki/src/SQLStore/QueryEngine/README.md new file mode 100644 index 00000000..a6d9dc21 --- /dev/null +++ b/www/wiki/extensions/SemanticMediaWiki/src/SQLStore/QueryEngine/README.md @@ -0,0 +1,61 @@ +# QueryEngine + +The `QueryEngine` handles the transformation of the `ask` query language into a `SQL` construct and is also +responsible to return query results from the `SQL` back-end with the help of the following components: + +- The `QuerySegmentListBuilder` transforms `ask` descriptions into individual `QuerySegment`'s (aka `QuerySegmentList`) +- The `DescriptionInterpreter` interface describes classes that are responsible to interpret a specific + `Description` object and turn it into an abstract `SQL` construct (a `QuerySegment`) +- The `QuerySegmentListProcessor` flattens and transforms a list of `QuerySegment`'s into a non-recursive + tree of `SQL` statements (including resolving of property/category hierarchies) +- The `ConceptQueryResolver` encapsulates query processing of a concept description in connection + with the `ConceptCache` class + +## Overview + + + +### Examples +```php +/** + * Equivalent to [[Category:Foo]] + */ +$classDescription = new ClassDescription( + new DIWikiPage( 'Foo', NS_CATEGORY ) +); + +/** + * Equivalent to [[:+]] + */ +$namespaceDescription = new NamespaceDescription( + NS_MAIN +); + +/** + * Equivalent to [[Foo::+]] + */ +$someProperty = new SomeProperty( + new DIProperty( 'Foo' ), + new ThingDescription() +); + +/** + * Equivalent to [[:+]][[Category:Foo]][[Foo::+]] + */ +$description = new Conjunction( [ + $namespaceDescription, + $classDescription, + $someProperty +] ); +``` +```php +$query = new Query( $description ); +$query->setLimit( 10 ); + +$sqlStorefactory = new SQLStoreFactory( + new SQLStore() +); + +$queryEngine = $sqlStorefactory->newMasterQueryEngine(); +$queryResult = $queryEngine->getQueryResult( $query ); +``` |