--- /dev/null
+// TR2 <bool_set> -*- C++ -*-
+
+// Copyright (C) 2009, 2011 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library 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 3, or (at your option)
+// any later version.
+
+// This library 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.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+// <http://www.gnu.org/licenses/>.
+
+/** @file tr2/bool_set
+ * This is a TR2 C++ Library header.
+ */
+
+#ifndef _GLIBCXX_TR2_BOOL_SET
+#define _GLIBCXX_TR2_BOOL_SET 1
+
+#pragma GCC system_header
+
+#include <typeinfo>
+#include <iostream>
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+namespace tr2
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+ /**
+ * bool_set
+ *
+ * See N2136, Bool_set: multi-valued logic
+ * by Hervé Brönnimann, Guillaume Melquiond, Sylvain Pion.
+ *
+ * The implicit conversion to bool is slippery! I may use the new
+ * explicit conversion. This has been specialized in the language
+ * so that in contexts requiring a bool the conversion happens
+ * implicitly. Thus most objections should be eliminated.
+ */
+ class bool_set
+ {
+ public:
+
+ /// Default constructor.
+ bool_set() : _M_b(_S_false) { }
+
+ /// Constructor from bool.
+ bool_set(bool __t) : _M_b(_Bool_set_val(__t)) { }
+
+ // I'm not sure about this.
+ bool contains(bool_set __b) const
+ { return this->is_singleton() && this->equals(__b); }
+
+ /// Return true if states are equal.
+ bool equals(bool_set __b) const
+ { return __b._M_b == _M_b; }
+
+ /// Return true if this is empty.
+ bool is_emptyset() const
+ { return _M_b == _S_empty; }
+
+ /// Return true if this is indeterminate.
+ bool is_indeterminate() const
+ { return _M_b == _S_indet; }
+
+ /// Return true if this is false or true (normal boolean).
+ bool is_singleton() const
+ { return _M_b == _S_false || _M_b == _S_true_; }
+
+ /// Conversion to bool.
+ //explicit
+ operator bool() const
+ {
+ if (! is_singleton())
+ throw std::bad_cast();
+ return _M_b;
+ }
+
+ ///
+ static bool_set indeterminate()
+ {
+ bool_set __b;
+ __b._M_b = _S_indet;
+ return __b;
+ }
+
+ ///
+ static bool_set emptyset()
+ {
+ bool_set __b;
+ __b._M_b = _S_empty;
+ return __b;
+ }
+
+ friend bool_set
+ operator!(bool_set __b)
+ { return __b._M_not(); }
+
+ friend bool_set
+ operator^(bool_set __s, bool_set __t)
+ { return __s._M_xor(__t); }
+
+ friend bool_set
+ operator|(bool_set __s, bool_set __t)
+ { return __s._M_or(__t); }
+
+ friend bool_set
+ operator&(bool_set __s, bool_set __t)
+ { return __s._M_and(__t); }
+
+ friend bool_set
+ operator==(bool_set __s, bool_set __t)
+ { return __s._M_eq(__t); }
+
+
+ // These overloads replace the facet additions in the paper!
+
+ template<typename CharT, typename Traits>
+ friend std::basic_ostream<CharT, Traits>&
+ operator<<(std::basic_ostream<CharT, Traits>& __out, bool_set __b)
+ {
+ int __a = __b._M_b;
+ __out << __a;
+ }
+
+ template<typename CharT, typename Traits>
+ friend std::basic_istream<CharT, Traits>&
+ operator>>(std::basic_istream<CharT, Traits>& __in, bool_set& __b)
+ {
+ long __c;
+ __in >> __c;
+ if (__c >= _S_false && __c < _S_empty)
+ __b._M_b = static_cast<_Bool_set_val>(__c);
+ }
+
+ private:
+
+ ///
+ enum _Bool_set_val: unsigned char
+ {
+ _S_false = 0,
+ _S_true_ = 1,
+ _S_indet = 2,
+ _S_empty = 3
+ };
+
+ /// Bool set state.
+ _Bool_set_val _M_b;
+
+ ///
+ bool_set(_Bool_set_val __c) : _M_b(__c) { }
+
+ ///
+ bool_set _M_not() const
+ { return _S_not[this->_M_b]; }
+
+ ///
+ bool_set _M_xor(bool_set __b) const
+ { return _S_xor[this->_M_b][__b._M_b]; }
+
+ ///
+ bool_set _M_or(bool_set __b) const
+ { return _S_or[this->_M_b][__b._M_b]; }
+
+ ///
+ bool_set _M_and(bool_set __b) const
+ { return _S_and[this->_M_b][__b._M_b]; }
+
+ ///
+ bool_set _M_eq(bool_set __b) const
+ { return _S_eq[this->_M_b][__b._M_b]; }
+
+ ///
+ static _Bool_set_val _S_not[4];
+
+ ///
+ static _Bool_set_val _S_xor[4][4];
+
+ ///
+ static _Bool_set_val _S_or[4][4];
+
+ ///
+ static _Bool_set_val _S_and[4][4];
+
+ ///
+ static _Bool_set_val _S_eq[4][4];
+ };
+
+ // 20.2.3.2 bool_set values
+
+ inline bool
+ contains(bool_set __s, bool_set __t)
+ { return __s.contains(__t); }
+
+ inline bool
+ equals(bool_set __s, bool_set __t)
+ { return __s.equals(__t); }
+
+ inline bool
+ is_emptyset(bool_set __b)
+ { return __b.is_emptyset(); }
+
+ inline bool
+ is_indeterminate(bool_set __b)
+ { return __b.is_indeterminate(); }
+
+ inline bool
+ is_singleton(bool_set __b)
+ { return __b.is_singleton(); }
+
+ inline bool
+ certainly(bool_set __b)
+ { return ! __b.contains(false); }
+
+ inline bool
+ possibly(bool_set __b)
+ { return __b.contains(true); }
+
+
+ // 20.2.3.3 bool_set set operations
+
+ inline bool_set
+ set_union(bool __s, bool_set __t)
+ { return bool_set(__s) | __t; }
+
+ inline bool_set
+ set_union(bool_set __s, bool __t)
+ { return __s | bool_set(__t); }
+
+ inline bool_set
+ set_union(bool_set __s, bool_set __t)
+ { return __s | __t; }
+
+ inline bool_set
+ set_intersection(bool __s, bool_set __t)
+ { return bool_set(__s) & __t; }
+
+ inline bool_set
+ set_intersection(bool_set __s, bool __t)
+ { return __s & bool_set(__t); }
+
+ inline bool_set
+ set_intersection(bool_set __s, bool_set __t)
+ { return __s & __t; }
+
+ inline bool_set
+ set_complement(bool_set __b)
+ { return ! __b; }
+
+
+ // 20.2.3.4 bool_set logical operators
+
+ inline bool_set
+ operator^(bool __s, bool_set __t)
+ { return bool_set(__s) ^ __t; }
+
+ inline bool_set
+ operator^(bool_set __s, bool __t)
+ { return __s ^ bool_set(__t); }
+
+ inline bool_set
+ operator|(bool __s, bool_set __t)
+ { return bool_set(__s) | __t; }
+
+ inline bool_set
+ operator|(bool_set __s, bool __t)
+ { return __s | bool_set(__t); }
+
+ inline bool_set
+ operator&(bool __s, bool_set __t)
+ { return bool_set(__s) & __t; }
+
+ inline bool_set
+ operator&(bool_set __s, bool __t)
+ { return __s & bool_set(__t); }
+
+
+ // 20.2.3.5 bool_set relational operators
+
+ inline bool_set
+ operator==(bool __s, bool_set __t)
+ { return bool_set(__s) == __t; }
+
+ inline bool_set
+ operator==(bool_set __s, bool __t)
+ { return __s == bool_set(__t); }
+
+ inline bool_set
+ operator!=(bool __s, bool_set __t)
+ { return ! (__s == __t); }
+
+ inline bool_set
+ operator!=(bool_set __s, bool __t)
+ { return ! (__s == __t); }
+
+ inline bool_set
+ operator!=(bool_set __s, bool_set __t)
+ { return ! (__s == __t); }
+
+_GLIBCXX_END_NAMESPACE_VERSION
+}
+}
+
+#include <tr2/bool_set.tcc>
+
+#endif // _GLIBCXX_TR2_BOOL_SET
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