variant_convert_construct.cpp 4.8 KB

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  1. // Copyright 2017 Peter Dimov.
  2. //
  3. // Distributed under the Boost Software License, Version 1.0.
  4. //
  5. // See accompanying file LICENSE_1_0.txt or copy at
  6. // http://www.boost.org/LICENSE_1_0.txt
  7. #include <boost/variant2/variant.hpp>
  8. #include <boost/core/lightweight_test.hpp>
  9. #include <boost/core/lightweight_test_trait.hpp>
  10. #include <type_traits>
  11. #include <utility>
  12. #include <string>
  13. using namespace boost::variant2;
  14. #define STATIC_ASSERT(...) static_assert(__VA_ARGS__, #__VA_ARGS__)
  15. struct X1
  16. {
  17. int v;
  18. X1(): v(0) {}
  19. explicit X1(int v): v(v) {}
  20. X1(X1 const& r): v(r.v) {}
  21. X1(X1&& r): v(r.v) {}
  22. X1& operator=( X1 const& r ) { v = r.v; return *this; }
  23. X1& operator=( X1&& r ) { v = r.v; return *this; }
  24. };
  25. inline bool operator==( X1 const& a, X1 const& b ) { return a.v == b.v; }
  26. STATIC_ASSERT( !std::is_nothrow_default_constructible<X1>::value );
  27. STATIC_ASSERT( !std::is_nothrow_copy_constructible<X1>::value );
  28. STATIC_ASSERT( !std::is_nothrow_move_constructible<X1>::value );
  29. STATIC_ASSERT( !std::is_nothrow_copy_assignable<X1>::value );
  30. STATIC_ASSERT( !std::is_nothrow_move_assignable<X1>::value );
  31. struct X2
  32. {
  33. int v;
  34. X2(): v(0) {}
  35. explicit X2(int v): v(v) {}
  36. X2(X2 const& r): v(r.v) {}
  37. X2(X2&& r): v(r.v) {}
  38. X2& operator=( X2 const& r ) { v = r.v; return *this; }
  39. X2& operator=( X2&& r ) { v = r.v; return *this; }
  40. };
  41. inline bool operator==( X2 const& a, X2 const& b ) { return a.v == b.v; }
  42. STATIC_ASSERT( !std::is_nothrow_default_constructible<X2>::value );
  43. STATIC_ASSERT( !std::is_nothrow_copy_constructible<X2>::value );
  44. STATIC_ASSERT( !std::is_nothrow_move_constructible<X2>::value );
  45. STATIC_ASSERT( !std::is_nothrow_copy_assignable<X2>::value );
  46. STATIC_ASSERT( !std::is_nothrow_move_assignable<X2>::value );
  47. int main()
  48. {
  49. {
  50. variant<int> v( 1 );
  51. variant<int, float> v2( v );
  52. BOOST_TEST( holds_alternative<int>( v2 ) );
  53. BOOST_TEST_EQ( get<int>( v ), get<int>( v2 ) );
  54. variant<int, float> v3( std::move(v) );
  55. BOOST_TEST( holds_alternative<int>( v3 ) );
  56. BOOST_TEST_EQ( get<int>( v2 ), get<int>( v3 ) );
  57. }
  58. {
  59. variant<int> const v( 1 );
  60. variant<int, float> v2( v );
  61. BOOST_TEST( holds_alternative<int>( v2 ) );
  62. BOOST_TEST_EQ( get<int>( v ), get<int>( v2 ) );
  63. variant<int, float> v3( std::move(v) );
  64. BOOST_TEST( holds_alternative<int>( v3 ) );
  65. BOOST_TEST_EQ( get<int>( v2 ), get<int>( v3 ) );
  66. }
  67. {
  68. variant<int const> v( 1 );
  69. variant<int const, float> v2( v );
  70. BOOST_TEST( holds_alternative<int const>( v2 ) );
  71. BOOST_TEST_EQ( get<int const>( v ), get<int const>( v2 ) );
  72. variant<int const, float> v3( std::move(v) );
  73. BOOST_TEST( holds_alternative<int const>( v3 ) );
  74. BOOST_TEST_EQ( get<int const>( v2 ), get<int const>( v3 ) );
  75. }
  76. {
  77. variant<int const> const v( 1 );
  78. variant<int const, float> v2( v );
  79. BOOST_TEST( holds_alternative<int const>( v2 ) );
  80. BOOST_TEST_EQ( get<int const>( v ), get<int const>( v2 ) );
  81. variant<int const, float> v3( std::move(v) );
  82. BOOST_TEST( holds_alternative<int const>( v3 ) );
  83. BOOST_TEST_EQ( get<int const>( v2 ), get<int const>( v3 ) );
  84. }
  85. {
  86. variant<float> v( 3.14f );
  87. variant<int, float> v2( v );
  88. BOOST_TEST( holds_alternative<float>( v2 ) );
  89. BOOST_TEST_EQ( get<float>( v ), get<float>( v2 ) );
  90. variant<int, float> v3( std::move(v) );
  91. BOOST_TEST( holds_alternative<float>( v3 ) );
  92. BOOST_TEST_EQ( get<float>( v2 ), get<float>( v3 ) );
  93. }
  94. {
  95. variant<float> v( 3.15f );
  96. variant<int, int, float> v2( v );
  97. BOOST_TEST( holds_alternative<float>( v2 ) );
  98. BOOST_TEST_EQ( get<float>( v ), get<float>( v2 ) );
  99. variant<int, int, float> v3( std::move(v) );
  100. BOOST_TEST( holds_alternative<float>( v3 ) );
  101. BOOST_TEST_EQ( get<float>( v2 ), get<float>( v3 ) );
  102. }
  103. {
  104. variant<float, std::string> v( "s1" );
  105. variant<int, int, float, std::string> v2( v );
  106. BOOST_TEST( holds_alternative<std::string>( v2 ) );
  107. BOOST_TEST_EQ( get<std::string>( v ), get<std::string>( v2 ) );
  108. variant<int, int, float, std::string> v3( std::move(v) );
  109. BOOST_TEST( holds_alternative<std::string>( v3 ) );
  110. BOOST_TEST_EQ( get<std::string>( v2 ), get<std::string>( v3 ) );
  111. }
  112. {
  113. variant<X1, X2> v{ X1{1} };
  114. variant<int, int, float, float, X1, X2> v2( v );
  115. BOOST_TEST( holds_alternative<X1>( v2 ) );
  116. BOOST_TEST_EQ( get<X1>( v ).v, get<X1>( v2 ).v );
  117. variant<int, int, float, float, X1, X2> v3( std::move(v) );
  118. BOOST_TEST( holds_alternative<X1>( v3 ) );
  119. BOOST_TEST_EQ( get<X1>( v2 ).v, get<X1>( v3 ).v );
  120. }
  121. return boost::report_errors();
  122. }