mapnik/include/utils.hpp

/* This file is part of Mapnik (c++ mapping toolkit)
 * Copyright (C) 2005 Artem Pavlenko
 *
 * Mapnik 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 2
 * of the License, or any later version.
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

//$Id: utils.hpp 39 2005-04-10 20:39:53Z pavlenko $

#ifndef UTILS_HPP
#define UTILS_HPP

#include <stdexcept>
#include <limits>
#include <ctime>
#include <sys/time.h>
#include <sstream>
#include <iostream>
#include <cmath>

#include <boost/thread/mutex.hpp>

namespace mapnik
{
    using boost::mutex;
    
    template <typename T>
    class CreateUsingNew
    {
    public:
	static T* create()
	{
	    return new T;
	}
	static void destroy(T* obj)
	{
	    delete obj;
	}
    };

    template <typename T>
    class CreateStatic
    {
    private:
	union MaxAlign
	{
	    char t_[sizeof(T)];
	    short int shortInt_;
	    int int_;
	    long int longInt_;
	    float float_;
	    double double_;
	    long double longDouble_;
	    struct Test;
	    int Test::* pMember_;
	    int (Test::*pMemberFn_)(int);
	};
    public:
	static T* create()
	{
	    static MaxAlign staticMemory;
	    return new(&staticMemory) T;
	}
	static void destroy(volatile T* obj)
	{
	    obj->~T();
	}
    };

    template <typename T,
	      template <typename T> class CreatePolicy=CreateStatic> class singleton
	      {
		  friend class CreatePolicy<T>;
		  static T* pInstance_;
		  static bool destroyed_;
		  singleton(const singleton &rhs);
		  singleton& operator=(const singleton&);
		  static void onDeadReference()
		  {
		      throw std::runtime_error("dead reference!");
		  }
	      protected:
		  static mutex mutex_;
		  singleton() {}
		  virtual ~singleton()
		  {
		      CreatePolicy<T>::destroy(pInstance_);
		      destroyed_=true;
		  }
	      public:
		  static  T* instance()
		  {
		      if (!pInstance_)
		      {
			  mutex::scoped_lock lock(mutex_);
			  if (!pInstance_)
			  {
			      if (destroyed_)
			      {
				  onDeadReference();
			      }
			      else
			      {
				  pInstance_=CreatePolicy<T>::create();
			      }
			  }
		      }
		      return pInstance_;
		  }
	      };

    template <typename T,
	      template <typename T> class CreatePolicy> mutex singleton<T,CreatePolicy>::mutex_;
    template <typename T,
	      template <typename T> class CreatePolicy> T* singleton<T,CreatePolicy>::pInstance_=0;
    template <typename T,
	      template <typename T> class CreatePolicy> bool singleton<T,CreatePolicy>::destroyed_=false;

    template <class T> class Handle
    {
        T* ptr_;
        int* pCount_;
    public:
	T* operator->() {return ptr_;}
	const T* operator->() const {return ptr_;}
	Handle(T* ptr)
	    :ptr_(ptr),pCount_(new int(1)) {}
	Handle(const Handle& rhs)
	    :ptr_(rhs.ptr_),pCount_(rhs.pCount_)
	{
	    (*pCount_)++;
	}
	Handle& operator=(const Handle& rhs)
	{
	    if (ptr_==rhs.ptr_) return *this;
	    if (--(*pCount_)==0)
	    {
		delete ptr_;
		delete pCount_;
	    }
	    ptr_=rhs.ptr_;
	    pCount_=rhs.pCount_;
	    (*pCount_)++;
	    return *this;
	}
	~Handle()
	{
	    if (--(*pCount_)==0)
	    {
		delete ptr_;
		delete pCount_;
	    }
	}
    };


    struct timer
    {
        struct timeval tv_;
        timer()
        {
            gettimeofday (&tv_,0);
        }
        void start()
        {
            gettimeofday (&tv_,0);
        }
        void stop()
        {
            timeval tv;
            gettimeofday (&tv,0);
            std::ostringstream s;
            long sec=1000*(tv.tv_sec-tv_.tv_sec);
            long total_ms=sec+static_cast<long>(0.001*(tv.tv_usec-tv_.tv_usec));
            s << "elapsed time is "<<total_ms<<" ms";
            std::clog<<s.str()<<std::endl;
        }
    };
    
    //converters
    class BadConversion : public std::runtime_error
    {
    public:
	BadConversion(const std::string& s)
	    :std::runtime_error(s)
	{}
    };
    
    template <typename T>
    inline std::string toString(const T& x)
    {
	std::ostringstream o;
	if (!(o << x))
	    throw BadConversion(std::string("toString(")
				+ typeid(x).name() + ")");
	return o.str();
    }
    
    template<typename T>
    inline void fromString(const std::string& s, T& x,
			   bool failIfLeftoverChars = true)
    {
	std::istringstream i(s);
	char c;
	if (!(i >> x) || (failIfLeftoverChars && i.get(c)))
	    throw BadConversion("fromString("+s+")");
    }
    
    inline bool space (char c)
    {
	return isspace(c);
    }
    
    inline bool not_space (char c)
    {
	return !isspace(c);
    }
    
    inline std::string trim_left(const std::string& str)
    {
	typedef std::string::const_iterator iter;
	iter i = find_if(str.begin(),str.end(),not_space);
	return std::string(i,str.end());	
    }
    inline std::string trim_right(const std::string& str)
    {
	std::string::size_type idx=str.find_last_not_of(" ");
	return str.substr(0,idx+1);
    }
    inline std::string trim(const std::string& str)
    {
	return trim_left(trim_right(str));
    }
}


#endif                                            //UTILS_HPP