com.hp.hpl.jena.graph.query
Interface QueryHandler

All Known Implementing Classes:

SimpleQueryHandler

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.

Author:

kers

Method Summary

boolean	containsNode(Node n) true iff the graph contains a triple in which n appears somewhere.
com.hp.hpl.jena.util.iterator.ExtendedIterator<Node>	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.
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)
com.hp.hpl.jena.util.iterator.ExtendedIterator<Node>	predicatesFor(Node s, Node o) Answer an iterator over all the predicates p such that (s, p, o) is in the underlying graph.
BindingQueryPlan	prepareBindings(GraphQuery 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_.
com.hp.hpl.jena.util.iterator.ExtendedIterator<Node>	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.

Method Detail

prepareBindings

BindingQueryPlan prepareBindings(GraphQuery q,
                                 Node[] variables)

prepare a plan for generating bindings given the query _q_ and the result variables _variables_.

patternStage

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. _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.

prepareTree

TreeQueryPlan prepareTree(Graph pattern)

deliver a plan for executing the tree-match query defined by _pattern_.

objectsFor

com.hp.hpl.jena.util.iterator.ExtendedIterator<Node> 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.

subjectsFor

com.hp.hpl.jena.util.iterator.ExtendedIterator<Node> 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.

predicatesFor

com.hp.hpl.jena.util.iterator.ExtendedIterator<Node> 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.

containsNode

boolean containsNode(Node n)

true iff the graph contains a triple in which n appears somewhere. if n is a fluid node, it is not defined whether true or false is returned, so don't do that.