Chris@16: // Copyright (C) 2003, Fernando Luis Cacciola Carballal.
Chris@16: //
Chris@16: // Use, modification, and distribution is subject to the Boost Software
Chris@16: // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: //
Chris@16: // See http://www.boost.org/libs/optional for documentation.
Chris@16: //
Chris@16: // You are welcome to contact the author at:
Chris@16: //  fernando_cacciola@hotmail.com
Chris@16: //
Chris@16: #ifndef BOOST_UTILITY_COMPARE_POINTEES_25AGO2003_HPP
Chris@16: #define BOOST_UTILITY_COMPARE_POINTEES_25AGO2003_HPP
Chris@16: 
Chris@16: #include<functional>
Chris@16: 
Chris@16: namespace boost {
Chris@16: 
Chris@16: // template<class OP> bool equal_pointees(OP const& x, OP const& y);
Chris@16: // template<class OP> struct equal_pointees_t;
Chris@16: //
Chris@16: // Being OP a model of OptionalPointee (either a pointer or an optional):
Chris@16: //
Chris@16: // If both x and y have valid pointees, returns the result of (*x == *y)
Chris@16: // If only one has a valid pointee, returns false.
Chris@16: // If none have valid pointees, returns true.
Chris@16: // No-throw
Chris@16: template<class OptionalPointee>
Chris@16: inline
Chris@16: bool equal_pointees ( OptionalPointee const& x, OptionalPointee const& y )
Chris@16: {
Chris@16:   return (!x) != (!y) ? false : ( !x ? true : (*x) == (*y) ) ;
Chris@16: }
Chris@16: 
Chris@16: template<class OptionalPointee>
Chris@16: struct equal_pointees_t : std::binary_function<OptionalPointee,OptionalPointee,bool>
Chris@16: {
Chris@16:   bool operator() ( OptionalPointee const& x, OptionalPointee const& y ) const
Chris@16:     { return equal_pointees(x,y) ; }
Chris@16: } ;
Chris@16: 
Chris@16: // template<class OP> bool less_pointees(OP const& x, OP const& y);
Chris@16: // template<class OP> struct less_pointees_t;
Chris@16: //
Chris@16: // Being OP a model of OptionalPointee (either a pointer or an optional):
Chris@16: //
Chris@16: // If y has not a valid pointee, returns false.
Chris@16: // ElseIf x has not a valid pointee, returns true.
Chris@16: // ElseIf both x and y have valid pointees, returns the result of (*x < *y)
Chris@16: // No-throw
Chris@16: template<class OptionalPointee>
Chris@16: inline
Chris@16: bool less_pointees ( OptionalPointee const& x, OptionalPointee const& y )
Chris@16: {
Chris@16:   return !y ? false : ( !x ? true : (*x) < (*y) ) ;
Chris@16: }
Chris@16: 
Chris@16: template<class OptionalPointee>
Chris@16: struct less_pointees_t : std::binary_function<OptionalPointee,OptionalPointee,bool>
Chris@16: {
Chris@16:   bool operator() ( OptionalPointee const& x, OptionalPointee const& y ) const
Chris@16:     { return less_pointees(x,y) ; }
Chris@16: } ;
Chris@16: 
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #endif
Chris@16: