Chris@16: // Three-state boolean logic library
Chris@16: 
Chris@16: // Copyright Douglas Gregor 2002-2004. Use, modification and
Chris@16: // distribution is subject to the Boost Software License, Version
Chris@16: // 1.0. (See accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: #ifndef BOOST_LOGIC_TRIBOOL_IO_HPP
Chris@16: #define BOOST_LOGIC_TRIBOOL_IO_HPP
Chris@16: 
Chris@16: #include <boost/logic/tribool.hpp>
Chris@16: #include <boost/detail/workaround.hpp>
Chris@16: #include <boost/noncopyable.hpp>
Chris@16: 
Chris@101: #if defined(_MSC_VER)
Chris@16: #  pragma once
Chris@16: #endif
Chris@16: 
Chris@16: #ifndef BOOST_NO_STD_LOCALE
Chris@16: #  include <locale>
Chris@16: #endif
Chris@16: 
Chris@16: #include <string>
Chris@16: #include <iostream>
Chris@16: 
Chris@16: namespace boost { namespace logic {
Chris@16: 
Chris@16: #ifdef BOOST_NO_STD_LOCALE
Chris@16: 
Chris@16: /**
Chris@16:  * \brief Returns a string containing the default name for the \c
Chris@16:  * false value of a tribool with the given character type T.
Chris@16:  *
Chris@16:  * This function only exists when the C++ standard library
Chris@16:  * implementation does not support locales.
Chris@16:  */
Chris@16: template<typename T> std::basic_string<T> default_false_name();
Chris@16: 
Chris@16: /**
Chris@16:  * \brief Returns the character string "false".
Chris@16:  *
Chris@16:  * This function only exists when the C++ standard library
Chris@16:  * implementation does not support locales.
Chris@16:  */
Chris@16: template<>
Chris@16: inline std::basic_string<char> default_false_name<char>()
Chris@16: { return "false"; }
Chris@16: 
Chris@16: #  ifndef BOOST_NO_WCHAR_T
Chris@16: /**
Chris@16:  * \brief Returns the wide character string L"false".
Chris@16:  *
Chris@16:  * This function only exists when the C++ standard library
Chris@16:  * implementation does not support locales.
Chris@16:  */
Chris@16: template<>
Chris@16: inline std::basic_string<wchar_t> default_false_name<wchar_t>()
Chris@16: { return L"false"; }
Chris@16: #  endif
Chris@16: 
Chris@16: /**
Chris@16:  * \brief Returns a string containing the default name for the \c true
Chris@16:  * value of a tribool with the given character type T.
Chris@16:  *
Chris@16:  * This function only exists when the C++ standard library
Chris@16:  * implementation does not support locales.
Chris@16:  */
Chris@16: template<typename T> std::basic_string<T> default_true_name();
Chris@16: 
Chris@16: /**
Chris@16:  * \brief Returns the character string "true".
Chris@16:  *
Chris@16:  * This function only exists when the C++ standard library
Chris@16:  * implementation does not support locales.
Chris@16:  */
Chris@16: template<>
Chris@16: inline std::basic_string<char> default_true_name<char>()
Chris@16: { return "true"; }
Chris@16: 
Chris@16: #  ifndef BOOST_NO_WCHAR_T
Chris@16: /**
Chris@16:  * \brief Returns the wide character string L"true".
Chris@16:  *
Chris@16:  *  This function only exists * when the C++ standard library
Chris@16:  *  implementation does not support * locales.
Chris@16:  */
Chris@16: template<>
Chris@16: inline std::basic_string<wchar_t> default_true_name<wchar_t>()
Chris@16: { return L"true"; }
Chris@16: #  endif
Chris@16: #endif
Chris@16: 
Chris@16: /**
Chris@16:  * \brief Returns a string containing the default name for the indeterminate
Chris@16:  * value of a tribool with the given character type T.
Chris@16:  *
Chris@16:  * This routine is used by the input and output streaming operators
Chris@16:  * for tribool when there is no locale support or the stream's locale
Chris@16:  * does not contain the indeterminate_name facet.
Chris@16:  */
Chris@16: template<typename T> std::basic_string<T> get_default_indeterminate_name();
Chris@16: 
Chris@16: /// Returns the character string "indeterminate".
Chris@16: template<>
Chris@16: inline std::basic_string<char> get_default_indeterminate_name<char>()
Chris@16: { return "indeterminate"; }
Chris@16: 
Chris@101: #ifndef BOOST_NO_WCHAR_T
Chris@16: /// Returns the wide character string L"indeterminate".
Chris@16: template<>
Chris@16: inline std::basic_string<wchar_t> get_default_indeterminate_name<wchar_t>()
Chris@16: { return L"indeterminate"; }
Chris@16: #endif
Chris@16: 
Chris@16: // http://www.cantrip.org/locale.html
Chris@16: 
Chris@16: #ifndef BOOST_NO_STD_LOCALE
Chris@16: /**
Chris@16:  * \brief A locale facet specifying the name of the indeterminate
Chris@16:  * value of a tribool.
Chris@16:  *
Chris@16:  * The facet is used to perform I/O on tribool values when \c
Chris@16:  * std::boolalpha has been specified. This class template is only
Chris@16:  * available if the C++ standard library implementation supports
Chris@16:  * locales.
Chris@16:  */
Chris@16: template<typename CharT>
Chris@16: class indeterminate_name : public std::locale::facet, private boost::noncopyable
Chris@16: {
Chris@16: public:
Chris@16:   typedef CharT char_type;
Chris@16:   typedef std::basic_string<CharT> string_type;
Chris@16: 
Chris@16:   /// Construct the facet with the default name
Chris@16:   indeterminate_name() : name_(get_default_indeterminate_name<CharT>()) {}
Chris@16: 
Chris@16:   /// Construct the facet with the given name for the indeterminate value
Chris@16:   explicit indeterminate_name(const string_type& initial_name)
Chris@16:   : name_(initial_name) {}
Chris@16: 
Chris@16:   /// Returns the name for the indeterminate value
Chris@16:   string_type name() const { return name_; }
Chris@16: 
Chris@16:   /// Uniquily identifies this facet with the locale.
Chris@16:   static std::locale::id id;
Chris@16: 
Chris@16: private:
Chris@16:   string_type name_;
Chris@16: };
Chris@16: 
Chris@16: template<typename CharT> std::locale::id indeterminate_name<CharT>::id;
Chris@16: #endif
Chris@16: 
Chris@16: /**
Chris@16:  * \brief Writes the value of a tribool to a stream.
Chris@16:  *
Chris@16:  * When the value of @p x is either \c true or \c false, this routine
Chris@16:  * is semantically equivalent to:
Chris@16:  * \code out << static_cast<bool>(x); \endcode
Chris@16:  *
Chris@16:  * When @p x has an indeterminate value, it outputs either the integer
Chris@16:  * value 2 (if <tt>(out.flags() & std::ios_base::boolalpha) == 0</tt>)
Chris@16:  * or the name of the indeterminate value. The name of the
Chris@16:  * indeterminate value comes from the indeterminate_name facet (if it
Chris@16:  * is defined in the output stream's locale), or from the
Chris@16:  * get_default_indeterminate_name function (if it is not defined in the
Chris@16:  * locale or if the C++ standard library implementation does not
Chris@16:  * support locales).
Chris@16:  *
Chris@16:  * \returns @p out
Chris@16:  */
Chris@16: template<typename CharT, typename Traits>
Chris@16: inline std::basic_ostream<CharT, Traits>&
Chris@16: operator<<(std::basic_ostream<CharT, Traits>& out, tribool x)
Chris@16: {
Chris@16:   if (!indeterminate(x)) {
Chris@16:     out << static_cast<bool>(x);
Chris@16:   } else {
Chris@16:     typename std::basic_ostream<CharT, Traits>::sentry cerberus(out);
Chris@16:     if (cerberus) {
Chris@16:       if (out.flags() & std::ios_base::boolalpha) {
Chris@16: #ifndef BOOST_NO_STD_LOCALE
Chris@16:         if (BOOST_HAS_FACET(indeterminate_name<CharT>, out.getloc())) {
Chris@16:           const indeterminate_name<CharT>& facet =
Chris@16:             BOOST_USE_FACET(indeterminate_name<CharT>, out.getloc());
Chris@16:           out << facet.name();
Chris@16:         } else {
Chris@16:           out << get_default_indeterminate_name<CharT>();
Chris@16:         }
Chris@16: #else
Chris@16:         out << get_default_indeterminate_name<CharT>();
Chris@16: #endif
Chris@16:       }
Chris@16:       else
Chris@16:         out << 2;
Chris@16:     }
Chris@16:   }
Chris@16:   return out;
Chris@16: }
Chris@16: 
Chris@16: /**
Chris@16:  * \brief Writes the indeterminate tribool value to a stream.
Chris@16:  *
Chris@16:  * This routine outputs either the integer
Chris@16:  * value 2 (if <tt>(out.flags() & std::ios_base::boolalpha) == 0</tt>)
Chris@16:  * or the name of the indeterminate value. The name of the
Chris@16:  * indeterminate value comes from the indeterminate_name facet (if it
Chris@16:  * is defined in the output stream's locale), or from the
Chris@16:  * get_default_indeterminate_name function (if it is not defined in the
Chris@16:  * locale or if the C++ standard library implementation does not
Chris@16:  * support locales).
Chris@16:  *
Chris@16:  * \returns @p out
Chris@16:  */
Chris@16: template<typename CharT, typename Traits>
Chris@16: inline std::basic_ostream<CharT, Traits>&
Chris@16: operator<<(std::basic_ostream<CharT, Traits>& out, 
Chris@16:            bool (*)(tribool, detail::indeterminate_t))
Chris@16: { return out << tribool(indeterminate); } 
Chris@16: 
Chris@16: /**
Chris@16:  * \brief Reads a tribool value from a stream.
Chris@16:  *
Chris@16:  * When <tt>(out.flags() & std::ios_base::boolalpha) == 0</tt>, this
Chris@16:  * function reads a \c long value from the input stream @p in and
Chris@16:  * converts that value to a tribool. If that value is 0, @p x becomes
Chris@16:  * \c false; if it is 1, @p x becomes \c true; if it is 2, @p becomes
Chris@16:  * \c indetermine; otherwise, the operation fails (and the fail bit is
Chris@16:  * set on the input stream @p in).
Chris@16:  *
Chris@16:  * When <tt>(out.flags() & std::ios_base::boolalpha) != 0</tt>, this
Chris@16:  * function first determines the names of the false, true, and
Chris@16:  * indeterminate values. The false and true names are extracted from
Chris@16:  * the \c std::numpunct facet of the input stream's locale (if the C++
Chris@16:  * standard library implementation supports locales), or from the \c
Chris@16:  * default_false_name and \c default_true_name functions (if there is
Chris@16:  * no locale support). The indeterminate name is extracted from the
Chris@16:  * appropriate \c indeterminate_name facet (if it is available in the
Chris@16:  * input stream's locale), or from the \c get_default_indeterminate_name
Chris@16:  * function (if the C++ standard library implementation does not
Chris@16:  * support locales, or the \c indeterminate_name facet is not
Chris@16:  * specified for this locale object). The input is then matched to
Chris@16:  * each of these names, and the tribool @p x is assigned the value
Chris@16:  * corresponding to the longest name that matched. If no name is
Chris@16:  * matched or all names are empty, the operation fails (and the fail
Chris@16:  * bit is set on the input stream @p in).
Chris@16:  *
Chris@16:  * \returns @p in
Chris@16:  */
Chris@16: template<typename CharT, typename Traits>
Chris@16: inline std::basic_istream<CharT, Traits>&
Chris@16: operator>>(std::basic_istream<CharT, Traits>& in, tribool& x)
Chris@16: {
Chris@16:   if (in.flags() & std::ios_base::boolalpha) {
Chris@16:     typename std::basic_istream<CharT, Traits>::sentry cerberus(in);
Chris@16:     if (cerberus) {
Chris@16:       typedef std::basic_string<CharT> string_type;
Chris@16: 
Chris@16: #ifndef BOOST_NO_STD_LOCALE
Chris@16:       const std::numpunct<CharT>& numpunct_facet =
Chris@16:         BOOST_USE_FACET(std::numpunct<CharT>, in.getloc());
Chris@16: 
Chris@16:       string_type falsename = numpunct_facet.falsename();
Chris@16:       string_type truename = numpunct_facet.truename();
Chris@16: 
Chris@16:       string_type othername;
Chris@16:       if (BOOST_HAS_FACET(indeterminate_name<CharT>, in.getloc())) {
Chris@16:         othername =
Chris@16:           BOOST_USE_FACET(indeterminate_name<CharT>, in.getloc()).name();
Chris@16:       } else {
Chris@16:         othername = get_default_indeterminate_name<CharT>();
Chris@16:       }
Chris@16: #else
Chris@16:       string_type falsename = default_false_name<CharT>();
Chris@16:       string_type truename = default_true_name<CharT>();
Chris@16:       string_type othername = get_default_indeterminate_name<CharT>();
Chris@16: #endif
Chris@16: 
Chris@16:       typename string_type::size_type pos = 0;
Chris@16:       bool falsename_ok = true, truename_ok = true, othername_ok = true;
Chris@16: 
Chris@16:       // Modeled after the code from Library DR 17
Chris@101:       while ((falsename_ok && pos < falsename.size())
Chris@101:              || (truename_ok && pos < truename.size())
Chris@101:              || (othername_ok && pos < othername.size())) {
Chris@16:         typename Traits::int_type c = in.get();
Chris@16:         if (c == Traits::eof())
Chris@16:           return in;
Chris@16: 
Chris@16:         bool matched = false;
Chris@16:         if (falsename_ok && pos < falsename.size()) {
Chris@16:           if (Traits::eq(Traits::to_char_type(c), falsename[pos]))
Chris@16:             matched = true;
Chris@16:           else
Chris@16:             falsename_ok = false;
Chris@16:         }
Chris@16: 
Chris@16:         if (truename_ok && pos < truename.size()) {
Chris@16:           if (Traits::eq(Traits::to_char_type(c), truename[pos]))
Chris@16:             matched = true;
Chris@16:           else
Chris@16:             truename_ok = false;
Chris@16:         }
Chris@16: 
Chris@16:         if (othername_ok && pos < othername.size()) {
Chris@16:           if (Traits::eq(Traits::to_char_type(c), othername[pos]))
Chris@16:             matched = true;
Chris@16:           else
Chris@16:             othername_ok = false;
Chris@16:         }
Chris@16: 
Chris@16:         if (matched) { ++pos; }
Chris@16:         if (pos > falsename.size()) falsename_ok = false;
Chris@16:         if (pos > truename.size())  truename_ok = false;
Chris@16:         if (pos > othername.size()) othername_ok = false;
Chris@16:       }
Chris@16: 
Chris@16:       if (pos == 0)
Chris@16:         in.setstate(std::ios_base::failbit);
Chris@16:       else {
Chris@16:         if (falsename_ok)      x = false;
Chris@16:         else if (truename_ok)  x = true;
Chris@16:         else if (othername_ok) x = indeterminate;
Chris@16:         else in.setstate(std::ios_base::failbit);
Chris@16:       }
Chris@16:     }
Chris@16:   } else {
Chris@16:     long value;
Chris@16:     if (in >> value) {
Chris@16:       switch (value) {
Chris@16:       case 0: x = false; break;
Chris@16:       case 1: x = true; break;
Chris@16:       case 2: x = indeterminate; break;
Chris@16:       default: in.setstate(std::ios_base::failbit); break;
Chris@16:       }
Chris@16:     }
Chris@16:   }
Chris@16: 
Chris@16:   return in;
Chris@16: }
Chris@16: 
Chris@16: } } // end namespace boost::logic
Chris@16: 
Chris@16: #endif // BOOST_LOGIC_TRIBOOL_IO_HPP