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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// UNSUPPORTED: c++03, c++11
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// <set>
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// class set
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// template<typename K>
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//     pair<iterator,iterator>             equal_range(const K& x);        //
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//     C++14
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// template<typename K>
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//     pair<const_iterator,const_iterator> equal_range(const K& x) const;  //
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//     C++14
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#include <cassert>
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#include <set>
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#include <utility>
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struct Comp {
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  using is_transparent = void;
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  bool operator()(const std::pair<int, int> &lhs,
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                  const std::pair<int, int> &rhs) const {
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    return lhs < rhs;
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  }
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  bool operator()(const std::pair<int, int> &lhs, int rhs) const {
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    return lhs.first < rhs;
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  }
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  bool operator()(int lhs, const std::pair<int, int> &rhs) const {
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    return lhs < rhs.first;
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  }
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};
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int main(int, char**) {
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  std::set<std::pair<int, int>, Comp> s{{2, 1}, {1, 2}, {1, 3}, {1, 4}, {2, 2}};
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  auto er = s.equal_range(1);
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  long nels = 0;
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  for (auto it = er.first; it != er.second; it++) {
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    assert(it->first == 1);
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    nels++;
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  }
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  assert(nels == 3);
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  return 0;
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}
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