////////////////////////////////////////////////////////////////////////////////
/// @brief arithmetic helpers
///
/// @file 
///
/// DISCLAIMER
///
/// Copyright 2010-2014 triagens GmbH, Cologne, Germany
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
///     http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.
///
/// Copyright holder is triAGENS GmbH, Cologne, Germany
///
/// @author Max Neunhoeffer
/// @author Copyright 2014, triagens GmbH, Cologne, Germany
////////////////////////////////////////////////////////////////////////////////

#ifndef ARANGODB_AQL_ARITHMETIC_H
#define ARANGODB_AQL_ARITHMETIC_H 1

#include "Basics/Common.h"

namespace triagens {
  namespace aql {

    template<typename T>
    bool IsUnsafeAddition (T l, T r) {
      return ((r > 0 && l > (std::numeric_limits<T>::max)() - r) ||
              (r < 0 && l < (std::numeric_limits<T>::min)() - r));
    }

    template<typename T>
    bool IsUnsafeSubtraction (T l, T r) {
      return ((r > 0 && l < (std::numeric_limits<T>::min)() + r) || (r < 0 && l > (std::numeric_limits<T>::max)() + r));
    }

    template<typename T>
    bool IsUnsafeMultiplication (T l, T r) {
      if (l > 0) {  
        if (r > 0) { 
          if (l > ((std::numeric_limits<T>::max)() / r)) {
            return true;
          }
        } 
        else { 
          if (r < ((std::numeric_limits<T>::min)() / l)) {
            return true;
          }
        } 
      } 
      else { 
        if (r > 0) { 
          if (l < ((std::numeric_limits<T>::min)() / r)) {
            return true;
          }
        } 
        else { 
          if ( (l != 0) && (r < ((std::numeric_limits<T>::max)() / l))) {
            return true;
          }
        } 
      }

      return false;
    }

    template<typename T>
    bool IsUnsafeDivision (T l, T r) {
      // note: the caller still has to check whether r is zero (division by zero)
      return (l == (std::numeric_limits<T>::min)() && r == -1);
    } 

  }
} 

#endif

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