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include/boost/logic/tribool_io.hpp  view on Meta::CPAN

template<typename T> std::basic_string<T> default_false_name();

/**
 * \brief Returns the character string "false".
 *
 * This function only exists when the C++ standard library
 * implementation does not support locales.
 */
template<>
inline std::basic_string<char> default_false_name<char>()
{ return "false"; }

#  ifndef BOOST_NO_WCHAR_T
/**
 * \brief Returns the wide character string L"false".
 *
 * This function only exists when the C++ standard library
 * implementation does not support locales.
 */
template<>
inline std::basic_string<wchar_t> default_false_name<wchar_t>()
{ return L"false"; }
#  endif

/**
 * \brief Returns a string containing the default name for the \c true
 * value of a tribool with the given character type T.
 *
 * This function only exists when the C++ standard library
 * implementation does not support locales.
 */
template<typename T> std::basic_string<T> default_true_name();

/**
 * \brief Returns the character string "true".
 *
 * This function only exists when the C++ standard library
 * implementation does not support locales.
 */
template<>
inline std::basic_string<char> default_true_name<char>()
{ return "true"; }

#  ifndef BOOST_NO_WCHAR_T
/**
 * \brief Returns the wide character string L"true".
 *
 *  This function only exists * when the C++ standard library
 *  implementation does not support * locales.
 */
template<>
inline std::basic_string<wchar_t> default_true_name<wchar_t>()
{ return L"true"; }
#  endif
#endif

/**
 * \brief Returns a string containing the default name for the indeterminate
 * value of a tribool with the given character type T.
 *
 * This routine is used by the input and output streaming operators
 * for tribool when there is no locale support or the stream's locale
 * does not contain the indeterminate_name facet.
 */
template<typename T> std::basic_string<T> get_default_indeterminate_name();

/// Returns the character string "indeterminate".
template<>
inline std::basic_string<char> get_default_indeterminate_name<char>()
{ return "indeterminate"; }

#ifndef BOOST_NO_WCHAR_T
/// Returns the wide character string L"indeterminate".
template<>
inline std::basic_string<wchar_t> get_default_indeterminate_name<wchar_t>()
{ return L"indeterminate"; }
#endif

// http://www.cantrip.org/locale.html

#ifndef BOOST_NO_STD_LOCALE
/**
 * \brief A locale facet specifying the name of the indeterminate
 * value of a tribool.
 *
 * The facet is used to perform I/O on tribool values when \c
 * std::boolalpha has been specified. This class template is only
 * available if the C++ standard library implementation supports
 * locales.
 */
template<typename CharT>
class indeterminate_name : public std::locale::facet, private boost::noncopyable
{
public:
  typedef CharT char_type;
  typedef std::basic_string<CharT> string_type;

  /// Construct the facet with the default name
  indeterminate_name() : name_(get_default_indeterminate_name<CharT>()) {}

  /// Construct the facet with the given name for the indeterminate value
  explicit indeterminate_name(const string_type& initial_name)
  : name_(initial_name) {}

  /// Returns the name for the indeterminate value
  string_type name() const { return name_; }

  /// Uniquily identifies this facet with the locale.
  static std::locale::id id;

private:
  string_type name_;
};

template<typename CharT> std::locale::id indeterminate_name<CharT>::id;
#endif

/**
 * \brief Writes the value of a tribool to a stream.
 *
 * When the value of @p x is either \c true or \c false, this routine