Squashed 'third_party/boostorg/detail/' content from commit 824721a
Change-Id: Id58ef7955aa7ca41b9e6b3f41ee1b0ad900985ea
git-subtree-dir: third_party/boostorg/detail
git-subtree-split: 824721a7533de893338ed5bbc8e8d9f4fb1ad716
diff --git a/include/boost/detail/identifier.hpp b/include/boost/detail/identifier.hpp
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+// boost/identifier.hpp ----------------------------------------------------//
+
+// Copyright Beman Dawes 2006
+
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+// See documentation at http://www.boost.org/libs/utility
+
+#ifndef BOOST_IDENTIFIER_HPP
+#define BOOST_IDENTIFIER_HPP
+
+#include <boost/utility/enable_if.hpp>
+#include <boost/type_traits/is_base_of.hpp>
+#include <iosfwd>
+
+namespace boost
+{
+ namespace detail
+ {
+ // class template identifier ---------------------------------------------//
+
+ // Always used as a base class so that different instantiations result in
+ // different class types even if instantiated with the same value type T.
+
+ // Expected usage is that T is often an integer type, best passed by
+ // value. There is no reason why T can't be a possibly larger class such as
+ // std::string, best passed by const reference.
+
+ // This implementation uses pass by value, based on expected common uses.
+
+ template <typename T, typename D>
+ class identifier
+ {
+ public:
+ typedef T value_type;
+
+ const value_type value() const { return m_value; }
+ void assign( value_type v ) { m_value = v; }
+
+ bool operator==( const D & rhs ) const { return m_value == rhs.m_value; }
+ bool operator!=( const D & rhs ) const { return m_value != rhs.m_value; }
+ bool operator< ( const D & rhs ) const { return m_value < rhs.m_value; }
+ bool operator<=( const D & rhs ) const { return m_value <= rhs.m_value; }
+ bool operator> ( const D & rhs ) const { return m_value > rhs.m_value; }
+ bool operator>=( const D & rhs ) const { return m_value >= rhs.m_value; }
+
+ typedef void (*unspecified_bool_type)(D); // without the D, unspecified_bool_type
+ static void unspecified_bool_true(D){} // conversion allows relational operators
+ // between different identifier types
+
+ operator unspecified_bool_type() const { return m_value == value_type() ? 0 : unspecified_bool_true; }
+ bool operator!() const { return m_value == value_type(); }
+
+ // constructors are protected so that class can only be used as a base class
+ protected:
+ identifier() {}
+ explicit identifier( value_type v ) : m_value(v) {}
+
+ private:
+ T m_value;
+ };
+
+ //#ifndef BOOST_NO_SFINAE
+
+ // template <class Ostream, class Id>
+ // typename enable_if< is_base_of< identifier< typename Id::value_type, Id >, Id >,
+ // Ostream & >::type operator<<( Ostream & os, const Id & id )
+ // {
+ // return os << id.value();
+ // }
+
+ // template <class Istream, class Id>
+ // typename enable_if< is_base_of< identifier< typename Id::value_type, Id >, Id >,
+ // Istream & >::type operator>>( Istream & is, Id & id )
+ // {
+ // typename Id::value_type v;
+ // is >> v;
+ // id.value( v );
+ // return is;
+ // }
+ //#endif
+
+ } // namespace detail
+} // namespace boost
+
+#endif // BOOST_IDENTIFIER_HPP