StdSingle.h

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/***************************************************************************
 *
 * Copyright (C) 2009-2010 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_KEY_CONVERTER_STDSINGLE_H_
#define KEYVALUE_KEY_CONVERTER_STDSINGLE_H_

#include "keyvalue/sys/exception/KV_ASSERT.h"
#include "keyvalue/value/Single.h"
#include "keyvalue/value/Variant.h"

namespace keyvalue {
namespace key {

template <typename ElementType>
class StdSingle {

public:

  typedef value::Single InputType_;

  typedef ElementType OutputType_;

  StdSingle(const InputType_& input, OutputType_* cache);

  bool
  isEmpty() const;

  value::Variant
  pop();

  void
  insert(const ElementType& element);

  OutputType_
  getOutput() const;

  bool
  mustUpdate() const;

private:

  const InputType_&   input_;
  OutputType_* const  cache_;
  OutputType_         output_;
  bool                empty_;
  bool                mustUpdate_;

};

/*--------------------------------------------------------------------------
 * StdSingle()
 *------------------------------------------------------------------------*/

template <typename ElementType>
StdSingle<ElementType>::StdSingle(const InputType_& input,
  OutputType_* const cache) : input_(input), cache_(cache), empty_(false),
  mustUpdate_(!cache) {
}

/*--------------------------------------------------------------------------
 * isEmpty()
 *------------------------------------------------------------------------*/

template <typename ElementType>
bool
StdSingle<ElementType>::isEmpty() const {
  return empty_;
}

/*--------------------------------------------------------------------------
 * pop()
 *------------------------------------------------------------------------*/

template <typename ElementType>
value::Variant
StdSingle<ElementType>::pop() {
  KV_ASSERT(!isEmpty(), "Element has been processed!");
  empty_ = true;
  return input_;
}

/*--------------------------------------------------------------------------
 * insert()
 *------------------------------------------------------------------------*/

template <typename ElementType>
void
StdSingle<ElementType>::insert(const ElementType& element) {
  output_ = element;
  mustUpdate_ = mustUpdate_ || output_ == *cache_;
}

/*--------------------------------------------------------------------------
 * getOutput()
 *------------------------------------------------------------------------*/

template <typename ElementType>
typename StdSingle<ElementType>::OutputType_
StdSingle<ElementType>::getOutput() const {
  return output_;
}

/*--------------------------------------------------------------------------
 * getOutput()
 *------------------------------------------------------------------------*/

template <typename ElementType>
bool
StdSingle<ElementType>::mustUpdate() const {
  return mustUpdate_;
}

} // namespace key
} // namespace keyvalue

#endif // KEYVALUE_KEY_CONVERTER_STDSINGLE_H_