id_generator.inl

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/** @file
 *  @author Bram de Greve (bram@cocamware.com)
 *  @author Tom De Muer (tom@cocamware.com)
 *
 *  *** BEGIN LICENSE INFORMATION ***
 *  
 *  The contents of this file are subject to the Common Public Attribution License 
 *  Version 1.0 (the "License"); you may not use this file except in compliance with 
 *  the License. You may obtain a copy of the License at 
 *  http://lass.sourceforge.net/cpal-license. The License is based on the 
 *  Mozilla Public License Version 1.1 but Sections 14 and 15 have been added to cover 
 *  use of software over a computer network and provide for limited attribution for 
 *  the Original Developer. In addition, Exhibit A has been modified to be consistent 
 *  with Exhibit B.
 *  
 *  Software distributed under the License is distributed on an "AS IS" basis, WITHOUT 
 *  WARRANTY OF ANY KIND, either express or implied. See the License for the specific 
 *  language governing rights and limitations under the License.
 *  
 *  The Original Code is LASS - Library of Assembled Shared Sources.
 *  
 *  The Initial Developer of the Original Code is Bram de Greve and Tom De Muer.
 *  The Original Developer is the Initial Developer.
 *  
 *  All portions of the code written by the Initial Developer are:
 *  Copyright (C) 2004-2022 the Initial Developer.
 *  All Rights Reserved.
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 *
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 *  GNU General Public License Version 2 or later (the GPL), in which case the 
 *  provisions of GPL are applicable instead of those above.  If you wish to allow use
 *  of your version of this file only under the terms of the GPL and not to allow 
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 *  
 *  *** END LICENSE INFORMATION ***
 */
 
 
 
#ifndef LASS_GUARDIAN_OF_INCLUSION_UTIL_ID_GENERATOR_INL
#define LASS_GUARDIAN_OF_INCLUSION_UTIL_ID_GENERATOR_INL
 
#include "id_generator.h"
#include "../num/num_traits.h"
 
 
 
namespace lass
{
 
namespace util
{
 
/** Construct an ID generator of which @a iFirstId is the first ID to be generated.
 */
template <typename T>
IdGenerator<T>::IdGenerator( typename CallTraits<T>::TParam iFirstId ):
    nextId_(iFirstId)
{
}
 
 
 
/** Generate an ID.
 *  Each call to this operator will give you a new ID incremented by one.
 *  @throw an exception is thrown if the generator can no longer increment the id field.
 *      Since the generator stores the id that will be returned on the next call, this means
 *      the maximum id returned will be @c num::NumTraits<T>::max-1
 */
template <typename T>
typename CallTraits<T>::TValue IdGenerator<T>::operator()()
{
    using TValue = typename CallTraits<T>::TValue;
    TValue currentId = nextId_.load(std::memory_order_acquire);
    TValue nextId {};
    do
    {
        if (currentId == num::NumTraits<TValue>::max)
        {
            LASS_THROW("ID overflow.  Can no longer increment ID field.");
        }
        nextId = static_cast<TValue>(currentId + 1);
    }
    while (!nextId_.compare_exchange_weak(currentId, nextId,
        std::memory_order_release, std::memory_order_relaxed));
    return currentId;
}
 
 
 
/** set the next ID to be drawn.
 */
template <typename T>
void IdGenerator<T>::setNext( typename CallTraits<T>::TParam iNextId )
{
    nextId_ = iNextId;
}
 
 
 
}
 
}
 
#endif