Calculator.h

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/***************************************************************************
 *
 * Copyright (C) 2009 Cassio Neri Moreira
 *
 * This file is part of the KeyValue library.
 *
 * The KeyValue library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or (at
 * your option) any later version.
 *
 * The KeyValue library 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 KeyValue. If not, see <http://www.gnu.org/licenses/>.
 *
 **************************************************************************/

#ifndef KEYVALUE_MNGT_CALCULATOR_H_
#define KEYVALUE_MNGT_CALCULATOR_H_

#include "keyvalue/mngt/Processor.h"
#include "keyvalue/mngt/ProcessorMngr.h"
#include "keyvalue/sys/exception/Exception.h"
#include "keyvalue/value/Variant.h"

namespace keyvalue {

template <typename Tag>
class Calculator : public Processor {

public:

  static Calculator&
  getInstance();

  const char*
  getName() const;

  value::Result
  getResult(const DataSet& data) const;

  value::Result
  getResult(const value::Variant& data) const;

  virtual value::Value
  getValue(const DataSet& data) const;

  virtual value::Value
  getValue(const value::Variant& data) const;

protected:

  // Constructor registers this into the ProcessorMngr
  Calculator();

  static void
  setGetter(Calculator& (*getter)());

private:

  static Calculator&
  getSingleton();

  static Calculator& (*getter_)();

}; // class Calculator

/*--------------------------------------------------------------------------
 * getInstance()
 *------------------------------------------------------------------------*/

template <typename Tag>
Calculator<Tag>&
Calculator<Tag>::getInstance() {
  return getter_();
}

template <typename Tag>
Calculator<Tag>& (*Calculator<Tag>::getter_)() = 
  Calculator<Tag>::getSingleton;

/*--------------------------------------------------------------------------
 * getResult()
 *------------------------------------------------------------------------*/

template <typename Tag>
value::Result
Calculator<Tag>::getResult(const DataSet& data) const {
  return getValue(data);
}

template <typename Tag>
value::Result
Calculator<Tag>::getResult(const value::Variant& data) const {
  return getValue(data);
}

/*--------------------------------------------------------------------------
 * getValue()
 *------------------------------------------------------------------------*/

template <typename Tag>
value::Value
Calculator<Tag>::getValue(const value::Variant& data) const {
  throw RuntimeError() & "Calculator '" & getName() & "' cannot build from "
    "input '" & data & "'!";
}

/*--------------------------------------------------------------------------
 * Calculator()
 *------------------------------------------------------------------------*/

template <typename Tag>
Calculator<Tag>::Calculator() {
  ProcessorMngr::getInstance().add(this);
}

/*--------------------------------------------------------------------------
 * setGetter()
 *------------------------------------------------------------------------*/

template <typename Tag>
void
Calculator<Tag>::setGetter(Calculator& (*getter)()) {
  getter_ = getter;
}

/*--------------------------------------------------------------------------
 * getSingleton()
 *------------------------------------------------------------------------*/

template <typename Tag>
Calculator<Tag>&
Calculator<Tag>::getSingleton() {
  static Calculator<Tag> singleton;
  return singleton;
}

} // namespace keyvalue

#endif // KEYVALUE_MNGT_CALCULATOR_H_