JRedirectAvailable.hh

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#ifndef __JLANG__JREDIRECTAVAILABLE__
#define __JLANG__JREDIRECTAVAILABLE__

#include <istream>
#include <ostream>

#include "JLang/JAnyType.hh"
#include "JLang/JNullType.hh"
#include "JLang/JTest.hh"
#include "JLang/JPrintHelper.hh"


/**
 * \author mdejong
 */

/**
 * Fallback implementation for <tt>std::istream& operator>>(std::istream, T&)</tt> 
 * for types that don't support the redirect operator.
 *
 * \param  in          input stream
 * \param  any_type    any  type
 * \return             null type
 */
JLANG::JNullType operator>>(std::istream& in, JLANG::JAnyType any_type);
  
  
/**
 * \cond NEVER
 * Fallback implementation for <tt>std::ostream& operator<<(std::ostream, const T&)</tt>
 * for types that don't support the redirect operator.
 *
 * \param  out         output stream
 * \param  any_type    any  type
 * \return             null type
 * \endcond
 */
//JLANG::JNullType operator<<(std::ostream& out, JLANG::JAnyType any_type);


/**
 * Test availability of redirect operators.
 */
template<class T, bool __str__ = JLANG::JPrintHelper::JMemberMethod<T>::__str__>
class JRedirectAvailable :
  public JLANG::JTest
{
  using JLANG::JTest::test;
  
  static JTrue test(std::istream&);
  static JTrue test(std::ostream&);
    
  static T& getReference();

  static std::istream& is();
  static std::ostream& os();
    
public:
  static const bool has_istream = JTEST(test(is() >> getReference()));  //!< true if <tt>std::istream& operator>>(std::istream&, T&)</tt> is defined; else false
  static const bool has_ostream = JTEST(test(os() << getReference()));  //!< true if <tt>std::ostream& operator<<(std::ostream&, const T&)</tt> is defined; else false
};


/**
 * Specialisation of JRedirectAvailable for class without member method <tt>__str__</tt>.
 */
template<class T>
class JRedirectAvailable<T, true> :
  public JLANG::JTest
{
public:
  static const bool has_istream = JRedirectAvailable<T, false>::has_istream;
  static const bool has_ostream = true;
};

#endif