Class Var

java.lang.Object

org.eclipse.rdf4j.query.algebra.AbstractQueryModelNode

org.eclipse.rdf4j.query.algebra.Var

All Implemented Interfaces:

Serializable, Cloneable, QueryModelNode, ValueExpr, VariableScopeChange

public class Var
extends AbstractQueryModelNode
implements ValueExpr

A variable that can contain a Value.

Service Provider–based construction: Prefer the Var.of(...) static factory methods over direct constructors. These factories delegate to a Var.Provider discovered via ServiceLoader or selected via the PROVIDER_PROPERTY system property. This allows third-party libraries to supply custom Var subclasses without changing call sites. If no provider is found, construction falls back to new Var(...).

To install a provider, add a file META-INF/services/org.eclipse.rdf4j.query.algebra.Var$Provider containing the implementing class name, or set system property PROVIDER_PROPERTY to a specific provider FQCN.

See Also:

• Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	Var.Provider	Service Provider Interface for globally controlling Var instantiation.

Field Summary

Fields

Modifier and Type	Field	Description
static final String	PROVIDER_PROPERTY	System property that, when set to a fully qualified class name implementing Var.Provider, selects that provider.

Constructor Summary

Constructors

Constructor	Description
Var(String name)	Deprecated, for removal: This API element is subject to removal in a future version. since 5.1.5, use of(String) instead.
Var(String name, boolean anonymous)	Deprecated, for removal: This API element is subject to removal in a future version. since 5.1.5, use of(String, boolean) instead.
Var(String name, Value value)	Deprecated, for removal: This API element is subject to removal in a future version. since 5.1.5, use of(String, Value) instead.
Var(String name, Value value, boolean anonymous)	Deprecated, for removal: This API element is subject to removal in a future version. since 5.1.5, use of(String, Value, boolean) instead.
Var(String name, Value value, boolean anonymous, boolean constant)	Deprecated, for removal: This API element is subject to removal in a future version. since 5.1.5, use of(String, Value, boolean, boolean) instead.

Method Summary

Modifier and Type	Method	Description
Var	clone()	Returns a (deep) clone of this query model node.
boolean	equals(Object o)	Returns true if this query model node and its children are recursively equal to o and its children.
String	getName()
String	getSignature()	Default implementation of QueryModelNode.getSignature() that prints the name of the node's class.
Value	getValue()
int	hashCode()
boolean	hasValue()
boolean	isAnonymous()
boolean	isConstant()
static Var	of(String name)	Factory mirroring Var(String).
static Var	of(String name, boolean anonymous)	Factory mirroring Var(String, boolean).
static Var	of(String name, Value value)	Factory mirroring Var(String, Value).
static Var	of(String name, Value value, boolean anonymous)	Factory mirroring Var(String, Value, boolean).
static Var	of(String name, Value value, boolean anonymous, boolean constant)	Factory mirroring Var(String, Value, boolean, boolean).
void	replaceChildNode(QueryModelNode current, QueryModelNode replacement)	Replaces one of the child nodes with a new node.
void	setParentNode(QueryModelNode parent)	Sets the node's parent.
protected boolean	spiEquals(Var other)	Extension hook for subclasses to participate in equals(Object) while preserving symmetry with other Var instances.
protected int	spiHashCode()	Extension hook for subclasses to contribute additional state to hashCode() while reusing the cached hash storage in Var.
<X extends Exception> void	visit(QueryModelVisitor<X> visitor)	Visits this node.
<X extends Exception> void	visitChildren(QueryModelVisitor<X> visitor)	Visits the children of this node.

Methods inherited from class AbstractQueryModelNode

getCardinality, getCostEstimate, getParentNode, getResultSizeActual, getResultSizeEstimate, getTotalTimeNanosActual, isCardinalitySet, isVariableScopeChange, nullEquals, replaceNodeInList, replaceWith, resetCardinality, setCardinality, setCostEstimate, setResultSizeActual, setResultSizeEstimate, setTotalTimeNanosActual, setVariableScopeChange, shouldCacheCardinality, toString

Methods inherited from class Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface QueryModelNode

getCostEstimate, getParentNode, getResultSizeActual, getResultSizeEstimate, getTotalTimeNanosActual, replaceWith, setCostEstimate, setResultSizeActual, setResultSizeEstimate, setTotalTimeNanosActual, toString

Field Details

PROVIDER_PROPERTY

public static final String PROVIDER_PROPERTY

System property that, when set to a fully qualified class name implementing Var.Provider, selects that provider. If absent, the first provider discovered by ServiceLoader is used; if none are found, a default provider that constructs Var directly is used.

See Also:

• Constant Field Values

Constructor Details

Var

@Deprecated(since="5.1.5",
            forRemoval=true)
public Var(String name,
 Value value,
 boolean anonymous,
 boolean constant)

Deprecated, for removal: This API element is subject to removal in a future version.

since 5.1.5, use of(String, Value, boolean, boolean) instead. Constructor will be made protected, subclasses may still use this method to instantiate themselves.

Parameters:

name -

value -

anonymous -

constant -

Var

@Deprecated(since="5.1.5",
            forRemoval=true)
public Var(String name)

Deprecated, for removal: This API element is subject to removal in a future version.

since 5.1.5, use of(String) instead.

Parameters:

name -

Var

@Deprecated(since="5.1.5",
            forRemoval=true)
public Var(String name,
 boolean anonymous)

Deprecated, for removal: This API element is subject to removal in a future version.

since 5.1.5, use of(String, boolean) instead.

Parameters:

name -

anonymous -

Var

@Deprecated(since="5.1.5",
            forRemoval=true)
public Var(String name,
 Value value)

Deprecated, for removal: This API element is subject to removal in a future version.

since 5.1.5, use of(String, Value) instead.

Parameters:

name -

value -

Var

@Deprecated(since="5.1.5",
            forRemoval=true)
public Var(String name,
 Value value,
 boolean anonymous)

Deprecated, for removal: This API element is subject to removal in a future version.

since 5.1.5, use of(String, Value, boolean) instead.

Parameters:

name -

value -

anonymous -

Method Details

of

public static Var of(String name)

Factory mirroring Var(String).

of

public static Var of(String name,
 boolean anonymous)

Factory mirroring Var(String, boolean).

of

public static Var of(String name,
 Value value)

Factory mirroring Var(String, Value).

of

public static Var of(String name,
 Value value,
 boolean anonymous)

Factory mirroring Var(String, Value, boolean).

of

public static Var of(String name,
 Value value,
 boolean anonymous,
 boolean constant)

Factory mirroring Var(String, Value, boolean, boolean).

isAnonymous

public boolean isAnonymous()

getName

public String getName()

hasValue

public boolean hasValue()

getValue

public Value getValue()

visit

public <X extends Exception> void visit(QueryModelVisitor<X> visitor)
                                 throws X

Description copied from interface: QueryModelNode

Visits this node. The node reports itself to the visitor with the proper runtime type.

Specified by:

visit in interface QueryModelNode

Throws:

X

visitChildren

public <X extends Exception> void visitChildren(QueryModelVisitor<X> visitor)
                                         throws X

Description copied from interface: QueryModelNode

Visits the children of this node. The node calls QueryModelNode.visit(QueryModelVisitor) on all of its child nodes.

Specified by:

visitChildren in interface QueryModelNode

Throws:

X

setParentNode

public void setParentNode(QueryModelNode parent)

Description copied from interface: QueryModelNode

Sets the node's parent.

Specified by:

setParentNode in interface QueryModelNode

Overrides:

setParentNode in class AbstractQueryModelNode

Parameters:

parent - The parent node for this node.

replaceChildNode

public void replaceChildNode(QueryModelNode current,
 QueryModelNode replacement)

Description copied from interface: QueryModelNode

Replaces one of the child nodes with a new node.

Specified by:

replaceChildNode in interface QueryModelNode

Parameters:

current - The current child node.

replacement - The new child node.

getSignature

public String getSignature()

Description copied from class: AbstractQueryModelNode

Default implementation of QueryModelNode.getSignature() that prints the name of the node's class.

Specified by:

getSignature in interface QueryModelNode

Overrides:

getSignature in class AbstractQueryModelNode

Returns:

The node's signature, e.g. SLICE (offset=10, limit=10).

equals

public boolean equals(Object o)

Description copied from interface: QueryModelNode

Returns true if this query model node and its children are recursively equal to o and its children.

Specified by:

equals in interface QueryModelNode

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

clone

public Var clone()

Description copied from interface: QueryModelNode

Returns a (deep) clone of this query model node. This method recursively clones the entire node tree, starting from this nodes.

Specified by:

clone in interface QueryModelNode

Specified by:

clone in interface ValueExpr

Overrides:

clone in class AbstractQueryModelNode

Returns:

A deep clone of this query model node.

spiEquals

protected boolean spiEquals(Var other)

Extension hook for subclasses to participate in equals(Object) while preserving symmetry with other Var instances.

spiHashCode

protected int spiHashCode()

Extension hook for subclasses to contribute additional state to hashCode() while reusing the cached hash storage in Var.

isConstant

public boolean isConstant()

Returns:

Returns the constant.