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dindexer/include/dindexer-machinery/scantask/leanbase.hpp

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/* Copyright 2015, 2016, Michele Santullo
* This file is part of "dindexer".
*
* "dindexer" 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.
*
* "dindexer" 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 "dindexer". If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef id982AF1D5C59C415584F56C1E6DDFE55E
#define id982AF1D5C59C415584F56C1E6DDFE55E
#include <ciso646>
#include <cassert>
#if !defined(NDEBUG)
# define LEANBASE_ASSERT_REENTRANCY
#endif
namespace mchlib {
namespace scantask {
#if defined(LEANBASE_ASSERT_REENTRANCY)
struct AutoSetBool {
explicit AutoSetBool ( bool* parBool ) :
m_bool(parBool)
{
assert(m_bool);
assert(not *m_bool);
*m_bool = true;
}
~AutoSetBool ( void ) noexcept {
*m_bool = false;
}
bool* m_bool;
};
#endif
template <typename T>
class LeanBase {
protected:
LeanBase ( void );
virtual ~LeanBase ( void ) noexcept = default;
void unset_data_created ( void );
public:
T& get_or_create ( void );
private:
virtual void on_data_fill ( void ) = 0;
virtual T& on_data_get ( void ) = 0;
bool m_data_created;
#if defined(LEANBASE_ASSERT_REENTRANCY)
bool m_inside_call;
#endif
};
template <typename T>
LeanBase<T>::LeanBase() :
m_data_created(false)
#if defined(LEANBASE_ASSERT_REENTRANCY)
, m_inside_call(false)
#endif
{
}
template <typename T>
T& LeanBase<T>::get_or_create() {
#if defined(LEANBASE_ASSERT_REENTRANCY)
assert(not m_inside_call);
AutoSetBool auto_bool(&m_inside_call);
#endif
if (not m_data_created) {
m_data_created = true;
this->on_data_fill();
}
return this->on_data_get();
}
template <typename T>
void LeanBase<T>::unset_data_created() {
assert(m_data_created);
m_data_created = false;
}
} //namespace scantask
} //namespace mchlib
#endif