/*
----
This file is part of SECONDO.

Copyright (C) 2004, University in Hagen, Department of Computer Science,
Database Systems for New Applications.

SECONDO is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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SECONDO is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with SECONDO; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
----

//paragraph [1] Title: [{\Large \bf \begin{center}] [\end{center}}]
//paragraph [10] Footnote: [{\footnote{] [}}]
//[TOC] [\tableofcontents]


[1] Implementation of the getRootNode Operator

[TOC]

0 Overview

1 Defines and Includes

*/

#include "op_getRootNode.h"

#include "ListUtils.h"
#include "QueryProcessor.h"


#include "BTree2.h"

extern NestedList *nl;
extern QueryProcessor *qp;

namespace BTree2Algebra {
namespace Operators {
/*
2 Operator ~getRootNode~

Signature is

----
    getRootNode: (btree2) --> (int)
----

2.1 TypeMapping for Operator ~getRootNode~

*/

ListExpr getRootNode::TypeMapping( ListExpr args){
    if(nl->ListLength(args) != 1){
       return listutils::typeError("Operator expects exactly one argument");
    }
    if(!listutils::isBTree2Description(nl->First(args))){
      return listutils::typeError("Operator expects a btree2 "
                                  "object as argument.");
    }
  return (nl->SymbolAtom(CcInt::BasicType()));
}

/*
2.2 Value Mapping

*/
int
getRootNode::ValueMapping(Word* args, Word& result, int message,
        Word& local, Supplier s)
{
  result = qp->ResultStorage(s);
  BTree2* btree = (BTree2*)args[0].addr;
  CcInt *res = (CcInt*) result.addr;
  res->Set( true, btree->GetRootNode() );
  return 0;
}

/*
2.3 Operator specification

*/
struct getRootNodeInfo : OperatorInfo {

  getRootNodeInfo() : OperatorInfo()
  {
    name =      "getRootNode";
    signature = "(btree2 Tk Td u) -> int";
    syntax =    "getRootNode ( _ )";
    meaning =   "Returns the SmiRecordId of the tree's root node.";
    example =   "query getRootNode (Staedte_btree2)";
  }
};

Operator getRootNode::def( getRootNodeInfo(), getRootNode::ValueMapping,
                          getRootNode::TypeMapping);

}
}