text: // Copyright (C) 2017 Andrzej Krzemienski.
  //
  // Use, modification, and distribution is subject to the Boost Software
  // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
  // http://www.boost.org/LICENSE_1_0.txt)
  //
  // See http://www.boost.org/lib/optional for documentation.
  //
  // You are welcome to contact the author at:
  //  akrzemi1@gmail.com
  
  #include "boost/optional/optional.hpp"
  
  #ifdef BOOST_BORLANDC
  #pragma hdrstop
  #endif
  
  #include "boost/core/ignore_unused.hpp"
  #include "boost/core/is_same.hpp"
  #include "boost/core/lightweight_test.hpp"
  #include "boost/core/lightweight_test_trait.hpp"
  
  
  using boost::optional;
  using boost::make_optional;
  using boost::core::is_same;
  
  template <typename Expected, typename Deduced>
  void verify_type(Deduced)
  {
    BOOST_TEST_TRAIT_TRUE(( is_same<Expected, Deduced> ));
  }
    
  #if (!defined BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES)
  struct MoveOnly
  {
    int value;
    explicit MoveOnly(int i) : value(i) {}
    MoveOnly(MoveOnly && r) : value(r.value) { r.value = 0; }
    MoveOnly& operator=(MoveOnly && r) { value = r.value; r.value = 0; return *this; }
    
  private:
    MoveOnly(MoveOnly const&);
    void operator=(MoveOnly const&);
  };
  
  MoveOnly makeMoveOnly(int i)
  {
    return MoveOnly(i);
  }
  
  void test_make_optional_for_move_only_type()
  {
    verify_type< optional<MoveOnly> >(make_optional(makeMoveOnly(2)));
    verify_type< optional<MoveOnly> >(make_optional(true, makeMoveOnly(2)));
    
    optional<MoveOnly> o1 = make_optional(makeMoveOnly(1));
    BOOST_TEST (o1);
    BOOST_TEST_EQ (1, o1->value);
    
    optional<MoveOnly> o2 = make_optional(true, makeMoveOnly(2));
    BOOST_TEST (o2);
    BOOST_TEST_EQ (2, o2->value);
    
    optional<MoveOnly> oN = make_optional(false, makeMoveOnly(2));
    BOOST_TEST (!oN);
  }
  
  #endif // !defined BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES
  
  void test_make_optional_for_optional()
  {
    optional<int> oi;
    verify_type< optional< optional<int> > >(make_optional(oi));
    verify_type< optional< optional<int> > >(make_optional(true, oi));
    
    optional< optional<int> > ooi = make_optional(oi);
    BOOST_TEST (ooi);
    BOOST_TEST (!*ooi);
    
    optional< optional<int> > ooT = make_optional(true, oi);
    BOOST_TEST (ooT);
    BOOST_TEST (!*ooT);
    
    optional< optional<int> > ooF = make_optional(false, oi);
    BOOST_TEST (!ooF);
  }
  
  void test_nested_make_optional()
  {
    verify_type< optional< optional<int> > >(make_optional(make_optional(1)));
    verify_type< optional< optional<int> > >(make_optional(true, make_optional(true, 2)));
    
    optional< optional<int> > oo1 = make_optional(make_optional(1));
    BOOST_TEST (oo1);
    BOOST_TEST (*oo1);
    BOOST_TEST_EQ (1, **oo1);
    
    optional< optional<int> > oo2 = make_optional(true, make_optional(true, 2));
    BOOST_TEST (oo2);
    BOOST_TEST (*oo2);
    BOOST_TEST_EQ (2, **oo2);
    
    optional< optional<int> > oo3 = make_optional(true, make_optional(false, 3));
    BOOST_TEST (oo3);
    BOOST_TEST (!*oo3);
    
    optional< optional<int> > oo4 = make_optional(false, make_optional(true, 4));
    BOOST_TEST (!oo4);
  }
  
  int main()
  {
  #if (!defined BOOST_OPTIONAL_DETAIL_NO_RVALUE_REFERENCES)
    test_make_optional_for_move_only_type();
  #endif
    test_make_optional_for_optional();
    test_nested_make_optional();
  
    return boost::report_errors();
  }
  