it.unibz.inf.ontop.iq.node

Interface QueryNode

All Superinterfaces:

Cloneable

All Known Subinterfaces:

AggregationNode, BinaryNonCommutativeOperatorNode, BinaryOrderedOperatorNode, CommutativeJoinNode, CommutativeJoinOrFilterNode, ConstructionNode, DataNode<P>, DistinctNode, EmptyNode, ExplicitVariableProjectionNode, ExtendedProjectionNode, ExtensionalDataNode, FilterNode, InnerJoinLikeNode, InnerJoinNode, IntensionalDataNode, JoinLikeNode, JoinOrFilterNode, LeafIQTree, LeftJoinNode, NaryOperatorNode, NativeNode, OrderByNode, QueryModifierNode, SliceNode, TrueNode, UnaryOperatorNode, UnionNode

All Known Implementing Classes:

AggregationNodeImpl, CompositeQueryNodeImpl, ConstructionNodeImpl, DataNodeImpl, DistinctNodeImpl, EmptyNodeImpl, ExtendedProjectionNodeImpl, ExtensionalDataNodeImpl, FilterNodeImpl, InnerJoinNodeImpl, IntensionalDataNodeImpl, JoinLikeNodeImpl, JoinOrFilterNodeImpl, LeafIQTreeImpl, LeftJoinNodeImpl, NativeNodeImpl, OrderByNodeImpl, QueryModifierNodeImpl, QueryNodeImpl, SliceNodeImpl, TrueNodeImpl, UnionNodeImpl

public interface QueryNode
extends Cloneable

Immutable. However, needs to be cloned to have multiple copies (distinct nodes) in an query tree. Only "QueryNode.equals(this)" returns true since multiple clones of a node may appear in the same IntermediateQuery and they must absolutely be distinguished. See IntermediateQueryFactory for creating new instances.

Method Summary

Modifier and Type	Method and Description
QueryNode	acceptNodeTransformer(HomogeneousQueryNodeTransformer transformer) "Accept" method for the "Visitor" pattern.
void	acceptVisitor(QueryNodeVisitor visitor) "Accept" method for the "Visitor" pattern.
QueryNode	clone() Cloning is needed for having multiple copies in the same intermediate query tree.
com.google.common.collect.ImmutableSet<Variable>	getLocallyDefinedVariables() Locally defined variables must not appear in the sub-tree
com.google.common.collect.ImmutableSet<Variable>	getLocallyRequiredVariables() Set of variables that this node, INDEPENDENTLY OF THE REQUIREMENTS OF ITS ANCESTORS, requires to be defined in the sub-tree.
com.google.common.collect.ImmutableSet<Variable>	getLocalVariables() Set of variables MENTIONED in the node, INDEPENDENTLY of its sub-tree.
com.google.common.collect.ImmutableSet<Variable>	getRequiredVariables(IntermediateQuery query) Set of variables which, individually, must be provided by at least one child, INDEPENDENTLY OF THE REQUIREMENTS OF THIS NODE'S ANCESTORS.
boolean	isEquivalentTo(QueryNode queryNode) Is syntactically equivalent
boolean	isSyntacticallyEquivalentTo(QueryNode node) TODO: explain
boolean	isVariableNullable(IntermediateQuery query, Variable variable) Returns true if it cannot guarantee the projected variable to be non-null Throws an IllegalArgumentException if the variable is not projected by the node

Method Detail

acceptVisitor

void acceptVisitor(QueryNodeVisitor visitor)

"Accept" method for the "Visitor" pattern. To be implemented by leaf classes.

clone

QueryNode clone()

Cloning is needed for having multiple copies in the same intermediate query tree.

acceptNodeTransformer

QueryNode acceptNodeTransformer(HomogeneousQueryNodeTransformer transformer)
                         throws QueryNodeTransformationException

"Accept" method for the "Visitor" pattern. To be implemented by leaf classes. If the transformation cannot be done, throw a QueryNodeTransformationException

Throws:

QueryNodeTransformationException

getLocalVariables

com.google.common.collect.ImmutableSet<Variable> getLocalVariables()

Set of variables MENTIONED in the node, INDEPENDENTLY of its sub-tree. See ImmutableQuery.getVariables(QueryNode node) for getting all the variables returned by the QueryNode.

isVariableNullable

boolean isVariableNullable(IntermediateQuery query,
                           Variable variable)

Returns true if it cannot guarantee the projected variable to be non-null Throws an IllegalArgumentException if the variable is not projected by the node

isSyntacticallyEquivalentTo

boolean isSyntacticallyEquivalentTo(QueryNode node)

TODO: explain

getLocallyRequiredVariables

com.google.common.collect.ImmutableSet<Variable> getLocallyRequiredVariables()

Set of variables that this node, INDEPENDENTLY OF THE REQUIREMENTS OF ITS ANCESTORS, requires to be defined in the sub-tree. Said differently, additional variable requirements may come from its ancestors.

getRequiredVariables

com.google.common.collect.ImmutableSet<Variable> getRequiredVariables(IntermediateQuery query)

Set of variables which, individually, must be provided by at least one child, INDEPENDENTLY OF THE REQUIREMENTS OF THIS NODE'S ANCESTORS. This may extend locally required variables. For instance, for a join node, this includes variables used in implicit joining conditions

getLocallyDefinedVariables

com.google.common.collect.ImmutableSet<Variable> getLocallyDefinedVariables()

Locally defined variables must not appear in the sub-tree

isEquivalentTo

boolean isEquivalentTo(QueryNode queryNode)

Is syntactically equivalent