Package org.eclipse.rdf4j.query.algebra.helpers

Class TupleExprs

java.lang.Object

org.eclipse.rdf4j.query.algebra.helpers.TupleExprs

public class TupleExprs
extends Object

Utility methods for TupleExpr objects.

Author:

Jeen Broekstra

Constructor Summary

Constructors

Constructor	Description
TupleExprs()

Method Summary

Modifier and Type	Method	Description
static boolean	containsExtension(TupleExpr t)	Verifies if the supplied TupleExpr contains a Extension.
static boolean	containsSubquery(TupleExpr t)	Verifies if the supplied TupleExpr contains a Projection with the subquery flag set to true (default).
static Var	createConstVar(Value value)	Creates an (anonymous) Var representing a constant value.
static List<TupleExpr>	getChildren(TupleExpr t)	Returns TupleExpr children of the given node.
static String	getConstVarName(Value value)
static boolean	isFilterExistsFunction(TupleExpr expr)	Verifies if the supplied expression is a FILTER (NOT) EXISTS operation
static boolean	isVariableScopeChange(TupleExpr expr)	Verifies if the supplied TupleExpr represents a variable scope change.

Methods inherited from class java.lang.Object

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

Constructor Details

TupleExprs

public TupleExprs()

Method Details

containsSubquery

public static boolean containsSubquery(TupleExpr t)

Verifies if the supplied TupleExpr contains a Projection with the subquery flag set to true (default). If the supplied TupleExpr is a Join or contains a Join, projections inside that Join's arguments will not be taken into account.

Parameters:

t - a tuple expression.

Returns:

true if the TupleExpr contains a subquery projection (outside of a Join), false otherwise.

containsExtension

public static boolean containsExtension(TupleExpr t)

Verifies if the supplied TupleExpr contains a Extension. If the supplied TupleExpr is a Join or contains a Join, a Service clause or a subquery element, extensions inside that element's argument will not be taken into account.

Parameters:

t - a tuple expression.

Returns:

true if the TupleExpr contains an Extension (outside of a Join, Service clause, or subquery), false otherwise.

isVariableScopeChange

public static boolean isVariableScopeChange(TupleExpr expr)

Verifies if the supplied TupleExpr represents a variable scope change.

Parameters:

expr - a TupleExpr

Returns:

true if the TupleExpr implements VariableScopeChange and has its scope change flag set to true, false otherwise.

getChildren

public static List<TupleExpr> getChildren(TupleExpr t)

Returns TupleExpr children of the given node.

Parameters:

t - a tuple expression.

Returns:

a list of TupleExpr children.

createConstVar

public static Var createConstVar(Value value)

Creates an (anonymous) Var representing a constant value. The variable name will be derived from the actual value to guarantee uniqueness.

Parameters:

value -

Returns:

an (anonymous) Var representing a constant value.

getConstVarName

public static String getConstVarName(Value value)

isFilterExistsFunction

public static boolean isFilterExistsFunction(TupleExpr expr)

Verifies if the supplied expression is a FILTER (NOT) EXISTS operation

Parameters:

expr - a tuple expression

Returns:

true if the supplied expression is a FILTER (NOT) EXISTS operation, false otherwise.