williamr@2: // Copyright (C) 2003, Fernando Luis Cacciola Carballal.
williamr@2: //
williamr@2: // Use, modification, and distribution is subject to the Boost Software
williamr@2: // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
williamr@2: // http://www.boost.org/LICENSE_1_0.txt)
williamr@2: //
williamr@2: // See http://www.boost.org/lib/optional for documentation.
williamr@2: //
williamr@2: // You are welcome to contact the author at:
williamr@2: //  fernando_cacciola@hotmail.com
williamr@2: //
williamr@2: #ifndef BOOST_UTILITY_COMPARE_POINTEES_25AGO2003_HPP
williamr@2: #define BOOST_UTILITY_COMPARE_POINTEES_25AGO2003_HPP
williamr@2: 
williamr@2: #include<functional>
williamr@2: 
williamr@2: namespace boost {
williamr@2: 
williamr@2: // template<class OP> bool equal_pointees(OP const& x, OP const& y);
williamr@2: // template<class OP> struct equal_pointees_t;
williamr@2: //
williamr@2: // Being OP a model of OptionalPointee (either a pointer or an optional):
williamr@2: //
williamr@2: // If both x and y have valid pointees, returns the result of (*x == *y)
williamr@2: // If only one has a valid pointee, returns false.
williamr@2: // If none have valid pointees, returns true.
williamr@2: // No-throw
williamr@2: template<class OptionalPointee>
williamr@2: inline
williamr@2: bool equal_pointees ( OptionalPointee const& x, OptionalPointee const& y )
williamr@2: {
williamr@2:   return (!x) != (!y) ? false : ( !x ? true : (*x) == (*y) ) ;
williamr@2: }
williamr@2: 
williamr@2: template<class OptionalPointee>
williamr@2: struct equal_pointees_t : std::binary_function<OptionalPointee,OptionalPointee,bool>
williamr@2: {
williamr@2:   bool operator() ( OptionalPointee const& x, OptionalPointee const& y ) const
williamr@2:     { return equal_pointees(x,y) ; }
williamr@2: } ;
williamr@2: 
williamr@2: // template<class OP> bool less_pointees(OP const& x, OP const& y);
williamr@2: // template<class OP> struct less_pointees_t;
williamr@2: //
williamr@2: // Being OP a model of OptionalPointee (either a pointer or an optional):
williamr@2: //
williamr@2: // If y has not a valid pointee, returns false.
williamr@2: // ElseIf x has not a valid pointee, returns true.
williamr@2: // ElseIf both x and y have valid pointees, returns the result of (*x < *y)
williamr@2: // No-throw
williamr@2: template<class OptionalPointee>
williamr@2: inline
williamr@2: bool less_pointees ( OptionalPointee const& x, OptionalPointee const& y )
williamr@2: {
williamr@2:   return !y ? false : ( !x ? true : (*x) < (*y) ) ;
williamr@2: }
williamr@2: 
williamr@2: template<class OptionalPointee>
williamr@2: struct less_pointees_t : std::binary_function<OptionalPointee,OptionalPointee,bool>
williamr@2: {
williamr@2:   bool operator() ( OptionalPointee const& x, OptionalPointee const& y ) const
williamr@2:     { return less_pointees(x,y) ; }
williamr@2: } ;
williamr@2: 
williamr@2: } // namespace boost
williamr@2: 
williamr@2: #endif
williamr@2: