assimp/code/TinyFormatter.h

/*
Open Asset Import Library (assimp)
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*/

/** @file  TinyFormatter.h
 *  @brief Utility to format log messages more easily. Introduced
 *    to get rid of the boost::format dependency. Much slinker,
 *    basically just extends stringstream.
 */
#ifndef INCLUDED_TINY_FORMATTER_H
#define INCLUDED_TINY_FORMATTER_H

#include <sstream>

namespace Assimp {
	namespace Formatter {

// ------------------------------------------------------------------------------------------------
/** stringstream utility. Usage:
 *  @code
 *  void writelog(const std::string&s);
 *  void writelog(const std::wstring&s);
 *  ...
 *  writelog(format()<< "hi! this is a number: " << 4);
 *  writelog(wformat()<< L"hi! this is a number: " << 4);
 *
 *  @endcode */
template < typename T,
	typename CharTraits = std::char_traits<T>,
	typename Allocator  = std::allocator<T>
> 
class basic_formatter 
{

public:

	typedef class std::basic_string< 
		T,CharTraits,Allocator
	> string;

	typedef class std::basic_ostringstream< 
		T,CharTraits,Allocator
	> stringstream;

public:

	basic_formatter() {}

	/* Allow basic_formatter<T>'s to be used almost interchangeably
	 * with std::(w)string or const (w)char* arguments because the
	 * conversion c'tor is called implicitly. */
	template <typename TT>
	basic_formatter(const TT& sin)	{
		underlying << sin;
	}


	// The problem described here:
	// https://sourceforge.net/tracker/?func=detail&atid=1067632&aid=3358562&group_id=226462
	// can also cause trouble here. Apparently, older gcc versions sometimes copy temporaries
	// being bound to const ref& function parameters. Copying streams is not permitted, though.
	// This workaround avoids this by manually specifying a copy ctor.
#if !defined(__GNUC__) || !defined(__APPLE__) || __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
	basic_formatter(const basic_formatter& other) {
		underlying << (string)other;
	}
#endif
	 

public:

	operator string () const {
		return underlying.str();
	}


	/* note - this is declared const because binding temporaries does only
	 * work for const references, so many function prototypes will 
	 * include const basic_formatter<T>& s but might still want to
	 * modify the formatted string without the need for a full copy.*/
	template <typename TToken>
	const basic_formatter& operator << (const TToken& s) const {
		underlying << s;
		return *this;
	}

	template <typename TToken>
	basic_formatter& operator << (const TToken& s) {
		underlying << s;
		return *this;
	}


	// comma operator overloaded as well, choose your preferred way.
	template <typename TToken>
	const basic_formatter& operator, (const TToken& s) const {
		underlying << s;
		return *this;
	}

	template <typename TToken>
	basic_formatter& operator, (const TToken& s) {
		underlying << s;
		return *this;
	}

	// Fix for MSVC8
	// See https://sourceforge.net/projects/assimp/forums/forum/817654/topic/4372824
	template <typename TToken>
	basic_formatter& operator, (TToken& s) {
		underlying << s;
		return *this;
	}


private:
	mutable stringstream underlying;
};


typedef basic_formatter< char > format;
typedef basic_formatter< wchar_t > wformat;

} // ! namespace Formatter 

} // ! namespace Assimp
#endif