How to use org.apache.jena.sparql.engine.ref

@Override
public void visit(OpQuadPattern quadPattern)
{
  push(Eval.evalQuadPattern(quadPattern, evaluator)) ;
}

@Override
public void visit(OpGraph opGraph)
{
  push(Eval.evalGraph(opGraph, evaluator)) ;
}

@Override
public void visit(OpDatasetNames dsNames)
{
  push(Eval.evalDS(dsNames, evaluator)) ;
}

@Override
public void visit(OpTopN opTop)
{
  Table table = eval(opTop.getSubOp()) ;
  //table = evaluator.topN(table, opTop.getLimti(), opTop.getConditions()) ;
  table = evaluator.order(table, opTop.getConditions()) ;
  table = evaluator.slice(table, 0, opTop.getLimit()) ;
  push(table) ;
}

@Override
public void visit(OpDistinct opDistinct)
{
  Table table = eval(opDistinct.getSubOp()) ;
  table = evaluator.distinct(table) ;
  push(table) ;
}

@Override
public void visit(OpList opList)
{
  Table table = eval(opList.getSubOp()) ;
  table = evaluator.list(table) ;
  push(table) ;
}

@Override
public void visit(OpConditional opCond)
{
  Table left = eval(opCond.getLeft()) ;
  // Ref engine - don;'t care about efficiency
  Table right = eval(opCond.getRight()) ;
  Table table = evaluator.condition(left, right) ;
  push(table) ;
}

@Override
public void visit(OpUnion opUnion)
{
  Table left = eval(opUnion.getLeft()) ;
  Table right = eval(opUnion.getRight()) ;
  Table table = evaluator.union(left, right) ;
  push(table) ;
}

@Override
public void visit(OpMinus opMinus)
{
  Table left = eval(opMinus.getLeft()) ;
  Table right = eval(opMinus.getRight()) ;
  Table table = evaluator.minus(left, right) ;
  push(table) ;
}

@Override
public void visit(OpProject opProject)
{
  Table table = eval(opProject.getSubOp()) ;
  table = evaluator.project(table, opProject.getVars()) ;
  push(table) ;
}

@Override
public void visit(OpAssign opAssign)
{
  Table table = eval(opAssign.getSubOp()) ;
  table = evaluator.assign(table, opAssign.getVarExprList()) ;
  push(table) ;
}

@Override
public void visit(OpFilter opFilter)
{
  Table table = eval(opFilter.getSubOp()) ;
  table = evaluator.filter(opFilter.getExprs(), table) ;
  push(table) ;
}

@Override
public void visit(OpOrder opOrder)
{
  Table table = eval(opOrder.getSubOp()) ;
  table = evaluator.order(table, opOrder.getConditions()) ;
  push(table) ;
}

@Override
public void visit(OpLeftJoin opLeftJoin)
{
  Table left = eval(opLeftJoin.getLeft()) ;
  Table right = eval(opLeftJoin.getRight()) ;
  Table table = evaluator.leftJoin(left, right, opLeftJoin.getExprs()) ;
  push(table) ;
}

@Override
public void visit(OpSlice opSlice)
{
  Table table = eval(opSlice.getSubOp()) ;
  table = evaluator.slice(table, opSlice.getStart(), opSlice.getLength()) ;
  push(table) ;
}

@Override
public void visit(OpPropFunc opPropFunc)
{
  Table table = eval(opPropFunc.getSubOp()) ;
  table = evaluator.propertyFunction(table, opPropFunc.getProperty(), opPropFunc.getSubjectArgs(), opPropFunc.getObjectArgs()) ;
  push(table) ;
}

@Override
public Plan create(Query query, DatasetGraph dataset, Binding binding, Context context)
{
  QueryEngineRef engine = new QueryEngineRef(query, dataset, binding, context) ;
  return engine.getPlan() ;
}

@Override
public Plan create(Op op, DatasetGraph dataset, Binding binding, Context context)
{
  QueryEngineRefQuad engine = new QueryEngineRefQuad(op, dataset, binding, context) ;
  return engine.getPlan() ;
}

@Override
public void visit(OpPath opPath)
{
  Table table = evaluator.pathPattern(opPath.getTriplePath()) ;
  push(table) ;
}

@Override
public Plan create(Op op, DatasetGraph dataset, Binding binding, Context context)
{
  QueryEngineRef engine = new QueryEngineRef(op, dataset, binding, context) ;
  return engine.getPlan() ;
}