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public interface QueryHandler
a QueryHandler handles queries on behalf of a graph. It's primary purpose is to isolate changes to the query interface away from the Graph; multiple different Graph implementations can use the same QueryHandler class, such as the built-in SimpleQueryHandler.
Method Summary | |
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boolean |
containsNode(Node n)
true iff the graph contains a triple in which n appears somewhere. |
ExtendedIterator |
objectsFor(Node s,
Node p)
deliver an iterator over all the objects _o_ such that _(s, p, o)_ is in the underlying graph; nulls count as wildcards. .remove() is not defined on this iterator. |
Stage |
patternStage(Mapping map,
ExpressionSet constraints,
Triple[] p)
produce a single Stage which will probe the underlying graph for triples matching p and inject all the resulting bindings into the processing stream (see Stage for details) _map_ is the variable binding map to use and update. |
ExtendedIterator |
predicatesFor(Node s,
Node o)
Answer an iterator over all the predicates p such that
(s, p, o) is in the underlying graph. .remove() is not
defined on this iterator. |
BindingQueryPlan |
prepareBindings(Query q,
Node[] variables)
prepare a plan for generating bindings given the query _q_ and the result variables _variables_. |
TreeQueryPlan |
prepareTree(Graph pattern)
deliver a plan for executing the tree-match query defined by _pattern_. |
ExtendedIterator |
subjectsFor(Node p,
Node o)
deliver an iterator over all the subjects _s_ such that _(s, p, o)_ is in the underlying graph; nulls count as wildcards. .remove() is not defined on this iterator. |
Method Detail |
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BindingQueryPlan prepareBindings(Query q, Node[] variables)
Stage patternStage(Mapping map, ExpressionSet constraints, Triple[] p)
_map_ is the variable binding map to use and update. _constraints_ is the current constraint expression: if this Stage can absorb some of the ANDed constraints, it may do so, and remove them from the ExpressionSet.
TreeQueryPlan prepareTree(Graph pattern)
ExtendedIterator objectsFor(Node s, Node p)
ExtendedIterator subjectsFor(Node p, Node o)
ExtendedIterator predicatesFor(Node s, Node o)
p
such that
(s, p, o)
is in the underlying graph. .remove() is not
defined on this iterator.
boolean containsNode(Node n)
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