de.fuberlin.wiwiss.d2rq.optimizer.expr

Class TransformExprToSQLApplyer

java.lang.Object

de.fuberlin.wiwiss.d2rq.optimizer.expr.TransformExprToSQLApplyer

All Implemented Interfaces:

ExprVisitor

public final class TransformExprToSQLApplyer
extends Object
implements ExprVisitor

Attempts to transform a SPARQL FILTER Expr to a SQL Expression Notes:

• Literals using d2rq:pattern cannot be compared.
• No XSD type checking/conversion or constructor functions yet.

Author:

Herwig Leimer, Giovanni Mels

Constructor Summary

Constructors

Constructor and Description
TransformExprToSQLApplyer(NodeRelation nodeRelation) Creates an expression transformer.

Method Summary

Methods

Modifier and Type	Method and Description
static Expression	convert(Expr expr, NodeRelation nodeRelation) Converts a SPARQL filter expression to an SQL expression
protected void	extensionConvert(ExprFunction function, List<Expression> args)
protected boolean	extensionSupports(ExprFunction function)
void	finishVisit()
Expression	result() Returns the sql Expression
void	startVisit()
void	visit(ExprAggregator eAgg)
void	visit(ExprFunction0 func)
void	visit(ExprFunction1 function)
void	visit(ExprFunction2 function)
void	visit(ExprFunction3 func)
void	visit(ExprFunctionN func)
void	visit(ExprFunctionOp funcOp)
void	visit(ExprVar var)
void	visit(NodeValue value)

Methods inherited from class java.lang.Object

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

Constructor Detail

TransformExprToSQLApplyer

public TransformExprToSQLApplyer(NodeRelation nodeRelation)

Creates an expression transformer.

Parameters:

nodeRelation -

Method Detail

convert

public static Expression convert(Expr expr,
                 NodeRelation nodeRelation)

Converts a SPARQL filter expression to an SQL expression

Parameters:

expr - The root node of an Expr tree, contains the SPARQL filter.

nodeRelation - The relation supplying the values to apply the filter on.

Returns:

The root node of an Expression tree, if conversion was successful, null otherwise.

result

public Expression result()

Returns the sql Expression

Returns:

the transformed sql expression if converting was possible, otherwise null.

startVisit

public void startVisit()

Specified by:

startVisit in interface ExprVisitor

finishVisit

public void finishVisit()

Specified by:

finishVisit in interface ExprVisitor

visit

public void visit(ExprFunction0 func)

Specified by:

visit in interface ExprVisitor

visit

public void visit(ExprFunction1 function)

Specified by:

visit in interface ExprVisitor

visit

public void visit(ExprFunction2 function)

Specified by:

visit in interface ExprVisitor

visit

public void visit(ExprFunction3 func)

Specified by:

visit in interface ExprVisitor

visit

public void visit(ExprFunctionN func)

Specified by:

visit in interface ExprVisitor

visit

public void visit(ExprFunctionOp funcOp)

Specified by:

visit in interface ExprVisitor

visit

public void visit(ExprAggregator eAgg)

Specified by:

visit in interface ExprVisitor

visit

public void visit(ExprVar var)

Specified by:

visit in interface ExprVisitor

visit

public void visit(NodeValue value)

Specified by:

visit in interface ExprVisitor

extensionSupports

protected boolean extensionSupports(ExprFunction function)

extensionConvert

protected void extensionConvert(ExprFunction function,
                    List<Expression> args)