48 lines · cpp
1//===----------------------------------------------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9// <map>10 11// class value_compare12 13// bool operator()( const value_type& lhs, const value_type& rhs ) const;14 15#include <map>16#include <cassert>17#include <string>18#include <utility>19 20template <typename Map>21struct CallCompMember : Map::value_compare {22 CallCompMember(const typename Map::value_compare& vc) : Map::value_compare(vc) {}23 24 typedef typename Map::value_type value_type;25 bool operator()(const value_type& value1, const value_type& value2) const {26 return this->comp(value1.first, value2.first);27 }28};29 30int main(int, char**) {31 typedef std::map<int, std::string> map_type;32 33 map_type m;34 std::pair<map_type::iterator, bool> p1 = m.insert(map_type::value_type(1, "abc"));35 std::pair<map_type::iterator, bool> p2 = m.insert(map_type::value_type(2, "abc"));36 37 const map_type::value_compare vc = m.value_comp();38 CallCompMember<map_type> call_comp = m.value_comp();39 40 assert(vc(*p1.first, *p2.first));41 assert(call_comp(*p1.first, *p2.first));42 43 assert(!vc(*p2.first, *p1.first));44 assert(!call_comp(*p2.first, *p1.first));45 46 return 0;47}48