/*
  FORMAT-COUT.hpp  -  use custom string conversions in stream output

  Copyright (C)         Lumiera.org
    2016,               Hermann Vosseler <Ichthyostega@web.de>

  This program 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 (at your option) 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., 675 Mass Ave, Cambridge, MA 02139, USA.

*/


/** @file format-cout.hpp
 ** Automatically use custom string conversion in C++ stream output.
 ** This diagnostics facility allows just to dump any object into `cout` or `cerr`.
 ** Pointers will be detected, checked for NULL and printed as address, followed
 ** by the representation of the pointee. When the displayed entity defines an
 ** `operator string()`, this custom string conversion will be used (suppressing
 ** any exceptions, of course). As fallback, a simplified type string is printed.
 ** 
 ** @see FormatHelper_test
 ** @see [frontend for boost::format, printf-style](format-string.hpp)
 ** 
 */


#ifndef LIB_FORMAT_COUT_H
#define LIB_FORMAT_COUT_H

#include "lib/format-obj.hpp"
//#include "lib/util.hpp"

#include <string>
#include <iostream>

// make those generally visible
using std::cout;
using std::cerr;
using std::endl;


  
namespace lib  {
namespace meta {
  
  /** when to use custom string conversions for output streams */
  template<typename X>
  struct use_StringConversion4Stream
    : __and_<std::is_class<typename Strip<X>::TypePlain>
            ,__not_<std::is_pointer<X>>
            ,__not_<can_lexical2string<X>>
            >
    { };
}}



namespace std {
  
  namespace { // toggle for the following generic overloads of operator<<
    
    template<typename X>
    using enable_StringConversion = lib::meta::enable_if< lib::meta::use_StringConversion4Stream<X>>;
  }
  
  
  /** generic overload to use custom string conversions in output */
  template<typename X, typename =    enable_StringConversion<X>>
  ostream&
  operator<< (ostream& os, X const& obj)
  {
    return os << lib::meta::CustomStringConv<X>::invoke (obj);
  }
  
  
  /** generic overload to pretty-print any pointer in output
   * @note possibly also invokes custom string conversion,
   *       in case the pointee defines one
   */
  template<typename X, typename =    enable_StringConversion<X>>
  ostream&
  operator<< (ostream& os, X* ptr)
  {
    if (ptr)
      return util::showAddr(os, ptr) << " ↗" << *ptr;
    else
      return os << "⟂ «" << lib::meta::typeStr<X>() << "»";
  }
  
  
  
} // namespace std
#endif /*LIB_FORMAT_COUT_H*/