it.unibz.inf.ontop.iq.node.impl

Class LeafIQTreeImpl

java.lang.Object

it.unibz.inf.ontop.iq.node.impl.QueryNodeImpl

it.unibz.inf.ontop.iq.node.impl.LeafIQTreeImpl

All Implemented Interfaces:

IQTree, LeafIQTree, ExplicitVariableProjectionNode, QueryNode, Cloneable

Direct Known Subclasses:

DataNodeImpl, EmptyNodeImpl, ExtensionalDataNodeImpl, NativeNodeImpl, TrueNodeImpl

public abstract class LeafIQTreeImpl
extends QueryNodeImpl
implements LeafIQTree

Field Summary

Fields

Modifier and Type	Field and Description
protected IntermediateQueryFactory	iqFactory

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	LeafIQTreeImpl(IQTreeTools iqTreeTools, IntermediateQueryFactory iqFactory)

Method Summary

Modifier and Type	Method and Description
IQTree	applyDescendingSubstitution(ImmutableSubstitution<? extends VariableOrGroundTerm> descendingSubstitution, Optional<ImmutableExpression> constraint) NB: the constraint is irrelevant here
com.google.common.collect.ImmutableList<IQTree>	getChildren()
com.google.common.collect.ImmutableSet<ImmutableSubstitution<NonVariableTerm>>	getPossibleVariableDefinitions() Returns a set of substitutions that define the projected variables when they are constructed.
LeafIQTree	getRootNode()
boolean	isConstructed(Variable variable) Returns true if the variable is (at least in one branch) constructed by a substitution (in a construction node)
boolean	isEquivalentTo(IQTree tree)
IQTree	liftIncompatibleDefinitions(Variable variable, VariableGenerator variableGenerator) Tries to lift unions when they have incompatible definitions for a variable.
IQTree	normalizeForOptimization(VariableGenerator variableGenerator)
IQTree	propagateDownConstraint(ImmutableExpression constraint) TODO: explain The constraint is used for pruning.
IQTree	removeDistincts() TODO: find a better name
IQTree	replaceSubTree(IQTree subTreeToReplace, IQTree newSubTree) If subTreeToReplace is not found, has no effect (besides creating a novel copy).

Methods inherited from class it.unibz.inf.ontop.iq.node.impl.QueryNodeImpl

clone

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface it.unibz.inf.ontop.iq.LeafIQTree

acceptNodeTransformer

Methods inherited from interface it.unibz.inf.ontop.iq.IQTree

acceptTransformer, acceptVisitor, applyDescendingSubstitutionWithoutOptimizing, applyFreshRenaming, getKnownVariables, getNotInternallyRequiredVariables, getVariableNullability, getVariables, inferUniqueConstraints, isDeclaredAsEmpty, isDistinct, isLeaf, validate

Methods inherited from interface it.unibz.inf.ontop.iq.node.ExplicitVariableProjectionNode

getVariables

Methods inherited from interface it.unibz.inf.ontop.iq.node.QueryNode

acceptVisitor, clone, getLocallyDefinedVariables, getLocallyRequiredVariables, getLocalVariables, getRequiredVariables, isEquivalentTo, isSyntacticallyEquivalentTo, isVariableNullable

Field Detail

iqFactory

protected final IntermediateQueryFactory iqFactory

Constructor Detail

LeafIQTreeImpl

protected LeafIQTreeImpl(IQTreeTools iqTreeTools,
                         IntermediateQueryFactory iqFactory)

Method Detail

getRootNode

public LeafIQTree getRootNode()

Specified by:

getRootNode in interface IQTree

Specified by:

getRootNode in interface LeafIQTree

getChildren

public com.google.common.collect.ImmutableList<IQTree> getChildren()

Specified by:

getChildren in interface IQTree

normalizeForOptimization

public IQTree normalizeForOptimization(VariableGenerator variableGenerator)

Specified by:

normalizeForOptimization in interface IQTree

isConstructed

public boolean isConstructed(Variable variable)

Description copied from interface: IQTree

Returns true if the variable is (at least in one branch) constructed by a substitution (in a construction node)

Specified by:

isConstructed in interface IQTree

isEquivalentTo

public boolean isEquivalentTo(IQTree tree)

Specified by:

isEquivalentTo in interface IQTree

applyDescendingSubstitution

public final IQTree applyDescendingSubstitution(ImmutableSubstitution<? extends VariableOrGroundTerm> descendingSubstitution,
                                                Optional<ImmutableExpression> constraint)

NB: the constraint is irrelevant here

Specified by:

applyDescendingSubstitution in interface IQTree

propagateDownConstraint

public IQTree propagateDownConstraint(ImmutableExpression constraint)

Description copied from interface: IQTree

TODO: explain The constraint is used for pruning. It remains enforced by a parent tree.

Specified by:

propagateDownConstraint in interface IQTree

replaceSubTree

public IQTree replaceSubTree(IQTree subTreeToReplace,
                             IQTree newSubTree)

Description copied from interface: IQTree

If subTreeToReplace is not found, has no effect (besides creating a novel copy).

Specified by:

replaceSubTree in interface IQTree

getPossibleVariableDefinitions

public com.google.common.collect.ImmutableSet<ImmutableSubstitution<NonVariableTerm>> getPossibleVariableDefinitions()

Description copied from interface: IQTree

Returns a set of substitutions that define the projected variables when they are constructed. Guarantee: each tuple in the result set having constructed values matches at least one of these substitutions. It is advised to call this method on a normalized IQ so as to reduce the number of possible substitutions (normalization drops unsatisfiable substitutions). The intended usage of this method it to determine the definition of a variable from the returned substitution. Therefore this method is robust to simple variable renaming and to multiple complex substitutions. E.g. if [x/x2], [x2/x3] and [x3/URI("http://myURI{}", x4] are three substitutions found in that order in a same branch, then x/URI("http://myURI{}", x4) will be the only output substitution for that branch.

Specified by:

getPossibleVariableDefinitions in interface IQTree

liftIncompatibleDefinitions

public IQTree liftIncompatibleDefinitions(Variable variable,
                                          VariableGenerator variableGenerator)

Description copied from interface: IQTree

Tries to lift unions when they have incompatible definitions for a variable. Union branches with compatible definitions are kept together

Specified by:

liftIncompatibleDefinitions in interface IQTree

removeDistincts

public IQTree removeDistincts()

Description copied from interface: IQTree

TODO: find a better name

Specified by:

removeDistincts in interface IQTree