Class LogicalOpMultiwayLeftJoin

java.lang.Object

se.liu.ida.hefquin.engine.queryplan.logical.impl.LogicalOpMultiwayLeftJoin

All Implemented Interfaces:

QueryPlanOperator, LogicalOperator, NaryLogicalOp

public class LogicalOpMultiwayLeftJoin
extends Object
implements NaryLogicalOp

A multiway left join corresponds to a sequence of SPARQL OPTIONAL clauses. Hence, it is not to be confused with nested OPTIONAL clauses (which would, instead, be captured as multiple nested multiway left joins).

Field Summary

Fields

Modifier and Type	Field	Description
protected static LogicalOpMultiwayLeftJoin	singleton

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	LogicalOpMultiwayLeftJoin()

Method Summary

Modifier and Type	Method	Description
boolean	equals(Object o)
ExpectedVariables	getExpectedVariables(ExpectedVariables... inputVars)	Returns the variables that can be expected in the solution mappings produced by this operator in the case that the input(s) to this operator contain solutions mappings with the given set(s) of variables.
static LogicalOpMultiwayLeftJoin	getInstance()
int	hashCode()
String	toString()
void	visit(LogicalPlanVisitor visitor)

Methods inherited from class java.lang.Object

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

Field Details

singleton

protected static LogicalOpMultiwayLeftJoin singleton

Constructor Details

LogicalOpMultiwayLeftJoin

protected LogicalOpMultiwayLeftJoin()

Method Details

getInstance

public static LogicalOpMultiwayLeftJoin getInstance()

getExpectedVariables

public ExpectedVariables getExpectedVariables(ExpectedVariables... inputVars)

Description copied from interface: QueryPlanOperator

Returns the variables that can be expected in the solution mappings produced by this operator in the case that the input(s) to this operator contain solutions mappings with the given set(s) of variables. The number of ExpectedVariables objects passed to this method must be in line with the degree of this operator (e.g., for a unary operator, exactly one such object must be passed).

Specified by:

getExpectedVariables in interface QueryPlanOperator

visit

public void visit(LogicalPlanVisitor visitor)

Specified by:

visit in interface LogicalOperator

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object