libstdc++
eq_by_less.hpp
Go to the documentation of this file.
00001 // -*- C++ -*-
00002 
00003 // Copyright (C) 2005, 2006, 2009, 2011 Free Software Foundation, Inc.
00004 //
00005 // This file is part of the GNU ISO C++ Library.  This library is free
00006 // software; you can redistribute it and/or modify it under the terms
00007 // of the GNU General Public License as published by the Free Software
00008 // Foundation; either version 3, or (at your option) any later
00009 // version.
00010 
00011 // This library is distributed in the hope that it will be useful, but
00012 // WITHOUT ANY WARRANTY; without even the implied warranty of
00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00014 // General Public License for more details.
00015 
00016 // Under Section 7 of GPL version 3, you are granted additional
00017 // permissions described in the GCC Runtime Library Exception, version
00018 // 3.1, as published by the Free Software Foundation.
00019 
00020 // You should have received a copy of the GNU General Public License and
00021 // a copy of the GCC Runtime Library Exception along with this program;
00022 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00023 // <http://www.gnu.org/licenses/>.
00024 
00025 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
00026 
00027 // Permission to use, copy, modify, sell, and distribute this software
00028 // is hereby granted without fee, provided that the above copyright
00029 // notice appears in all copies, and that both that copyright notice
00030 // and this permission notice appear in supporting documentation. None
00031 // of the above authors, nor IBM Haifa Research Laboratories, make any
00032 // representation about the suitability of this software for any
00033 // purpose. It is provided "as is" without express or implied
00034 // warranty.
00035 
00036 /**
00037  * @file eq_by_less.hpp
00038  * Contains an equivalence function.
00039  */
00040 
00041 #ifndef PB_DS_EQ_BY_LESS_HPP
00042 #define PB_DS_EQ_BY_LESS_HPP
00043 
00044 #include <utility>
00045 #include <functional>
00046 #include <vector>
00047 #include <assert.h>
00048 #include <ext/pb_ds/detail/types_traits.hpp>
00049 
00050 namespace __gnu_pbds
00051 {
00052   namespace detail
00053   {
00054     /// Equivalence function.
00055     template<typename Key, class Cmp_Fn>
00056     struct eq_by_less : private Cmp_Fn
00057     {
00058       bool
00059       operator()(const Key& r_lhs, const Key& r_rhs) const
00060       {
00061     const bool l = Cmp_Fn::operator()(r_lhs, r_rhs);
00062     const bool g = Cmp_Fn::operator()(r_rhs, r_lhs);
00063     return !(l || g);
00064       }
00065     };
00066   } // namespace detail
00067 } // namespace __gnu_pbds
00068 
00069 #endif // #ifndef PB_DS_EQ_BY_LESS_HPP