llvm-project

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//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// <map>
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// class value_compare
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// bool operator()( const value_type& lhs, const value_type& rhs ) const;
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#include <map>
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#include <cassert>
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#include <string>
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#include <utility>
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template <typename MMap>
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struct CallCompMember : MMap::value_compare {
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    CallCompMember(const typename MMap::value_compare& vc) : MMap::value_compare(vc) {}
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    typedef typename MMap::value_type value_type;
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    bool operator()(const value_type& value1, const value_type& value2) const {
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        return this->comp(value1.first, value2.first);
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    }
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};
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int main(int, char**) {
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    typedef std::multimap<int, std::string> map_type;
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    map_type m;
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    map_type::iterator i1 = m.insert(map_type::value_type(1, "abc"));
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    map_type::iterator i2 = m.insert(map_type::value_type(2, "abc"));
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    const map_type::value_compare vc = m.value_comp();
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    CallCompMember<map_type> call_comp = m.value_comp();
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    assert(vc(*i1, *i2));
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    assert(call_comp(*i1, *i2));
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    assert(!vc(*i2, *i1));
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    assert(!call_comp(*i2, *i1));
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    return 0;
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}
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