168 lines
4 KiB
C++
168 lines
4 KiB
C++
/*****************************************************************************
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*
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* This file is part of Mapnik (c++ mapping toolkit)
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*
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* Copyright (C) 2011 Artem Pavlenko
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*****************************************************************************/
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#ifndef MAPNIK_UTILS_HPP
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#define MAPNIK_UTILS_HPP
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// boost
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#ifdef MAPNIK_THREADSAFE
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#include <boost/thread/mutex.hpp>
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#endif
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// stl
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#include <stdexcept>
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#include <cstdlib>
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#include <limits>
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#include <ctime>
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#include <algorithm>
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#include <cmath>
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namespace mapnik
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{
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#ifdef MAPNIK_THREADSAFE
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using boost::mutex;
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#endif
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template <typename T>
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class CreateUsingNew
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{
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public:
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static T* create()
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{
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return new T;
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}
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static void destroy(T* obj)
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{
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delete obj;
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}
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};
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template <typename T>
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class CreateStatic
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{
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private:
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union MaxAlign
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{
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char t_[sizeof(T)];
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short int shortInt_;
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int int_;
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long int longInt_;
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float float_;
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double double_;
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long double longDouble_;
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struct Test;
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int Test::* pMember_;
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int (Test::*pMemberFn_)(int);
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};
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public:
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static T* create()
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{
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static MaxAlign staticMemory;
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return new(&staticMemory) T;
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}
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#ifdef __SUNPRO_CC
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// Sun C++ Compiler doesn't handle `volatile` keyword same as GCC.
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static void destroy(T* obj)
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#else
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static void destroy(volatile T* obj)
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#endif
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{
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obj->~T();
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}
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};
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template <typename T,
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template <typename U> class CreatePolicy=CreateStatic> class singleton
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{
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#ifdef __SUNPRO_CC
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/* Sun's C++ compiler will issue the following errors if CreatePolicy<T> is used:
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Error: A class template name was expected instead of mapnik::CreatePolicy<mapnik::T>
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Error: A "friend" declaration must specify a class or function.
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*/
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friend class CreatePolicy;
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#else
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friend class CreatePolicy<T>;
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#endif
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static T* pInstance_;
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static bool destroyed_;
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singleton(const singleton &rhs);
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singleton& operator=(const singleton&);
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static void onDeadReference()
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{
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throw std::runtime_error("dead reference!");
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}
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static void DestroySingleton()
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{
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CreatePolicy<T>::destroy(pInstance_);
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pInstance_ = 0;
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destroyed_ = true;
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}
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protected:
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#ifdef MAPNIK_THREADSAFE
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static mutex mutex_;
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#endif
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singleton() {}
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public:
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static T& instance()
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{
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if (! pInstance_)
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{
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#ifdef MAPNIK_THREADSAFE
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mutex::scoped_lock lock(mutex_);
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#endif
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if (! pInstance_)
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{
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if (destroyed_)
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{
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destroyed_ = false;
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onDeadReference();
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}
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else
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{
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pInstance_ = CreatePolicy<T>::create();
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// register destruction
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std::atexit(&DestroySingleton);
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}
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}
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}
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return *pInstance_;
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}
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};
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#ifdef MAPNIK_THREADSAFE
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template <typename T,
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template <typename U> class CreatePolicy> mutex singleton<T,CreatePolicy>::mutex_;
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#endif
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template <typename T,
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template <typename U> class CreatePolicy> T* singleton<T,CreatePolicy>::pInstance_=0;
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template <typename T,
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template <typename U> class CreatePolicy> bool singleton<T,CreatePolicy>::destroyed_=false;
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}
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#endif // MAPNIK_UTILS_HPP
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