test/src/unit-udt.cpp - third_party/json - Git at Google

 /*
     __ _____ _____ _____
  __|  |   __|     |   | |  JSON for Modern C++ (test suite)
 |  |  |__   |  |  | | | |  version 3.8.0
 |_____|_____|_____|_|___|  https://github.com/nlohmann/json

 Licensed under the MIT License <http://opensource.org/licenses/MIT>.
 SPDX-License-Identifier: MIT
 Copyright (c) 2013-2019 Niels Lohmann <http://nlohmann.me>.

 Permission is hereby  granted, free of charge, to any  person obtaining a copy
 of this software and associated  documentation files (the "Software"), to deal
 in the Software  without restriction, including without  limitation the rights
 to  use, copy,  modify, merge,  publish, distribute,  sublicense, and/or  sell
 copies  of  the Software,  and  to  permit persons  to  whom  the Software  is
 furnished to do so, subject to the following conditions:

 The above copyright notice and this permission notice shall be included in all
 copies or substantial portions of the Software.

 THE SOFTWARE  IS PROVIDED "AS  IS", WITHOUT WARRANTY  OF ANY KIND,  EXPRESS OR
 IMPLIED,  INCLUDING BUT  NOT  LIMITED TO  THE  WARRANTIES OF  MERCHANTABILITY,
 FITNESS FOR  A PARTICULAR PURPOSE AND  NONINFRINGEMENT. IN NO EVENT  SHALL THE
 AUTHORS  OR COPYRIGHT  HOLDERS  BE  LIABLE FOR  ANY  CLAIM,  DAMAGES OR  OTHER
 LIABILITY, WHETHER IN AN ACTION OF  CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE  OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 */

 #include "doctest_compatibility.h"

 #include <nlohmann/json.hpp>
 using nlohmann::json;

 #include <array>
 #include <map>
 #include <string>
 #include <memory>

 namespace udt
 {
 enum class country
 {
     china,
     france,
     russia
 };

 struct age
 {
     int m_val;
     age(int rhs = 0) : m_val(rhs) {}
 };

 struct name
 {
     std::string m_val;
     name(const std::string rhs = "") : m_val(rhs) {}
 };

 struct address
 {
     std::string m_val;
     address(const std::string rhs = "") : m_val(rhs) {}
 };

 struct person
 {
     age m_age;
     name m_name;
     country m_country;
     person() : m_age(), m_name(), m_country() {}
     person(const age& a, const name& n, const country& c) : m_age(a), m_name(n), m_country(c) {}
 };

 struct contact
 {
     person m_person;
     address m_address;
     contact() : m_person(), m_address() {}
     contact(const person& p, const address& a) : m_person(p), m_address(a) {}
 };

 struct contact_book
 {
     name m_book_name;
     std::vector<contact> m_contacts;
     contact_book() : m_book_name(), m_contacts() {}
     contact_book(const name& n, const std::vector<contact>& c) : m_book_name(n), m_contacts(c) {}
 };
 }

 // to_json methods
 namespace udt
 {
 // templates because of the custom_json tests (see below)
 template <typename BasicJsonType>
 static void to_json(BasicJsonType& j, age a)
 {
     j = a.m_val;
 }

 template <typename BasicJsonType>
 static void to_json(BasicJsonType& j, const name& n)
 {
     j = n.m_val;
 }

 template <typename BasicJsonType>
 static void to_json(BasicJsonType& j, country c)
 {
     switch (c)
     {
         case country::china:
             j = u8"中华人民共和国";
             return;
         case country::france:
             j = "France";
             return;
         case country::russia:
             j = u8"Российская Федерация";
             return;
         default:
             break;
     }
 }

 template <typename BasicJsonType>
 static void to_json(BasicJsonType& j, const person& p)
 {
     j = BasicJsonType{{"age", p.m_age}, {"name", p.m_name}, {"country", p.m_country}};
 }

 static void to_json(nlohmann::json& j, const address& a)
 {
     j = a.m_val;
 }

 static void to_json(nlohmann::json& j, const contact& c)
 {
     j = json{{"person", c.m_person}, {"address", c.m_address}};
 }

 static void to_json(nlohmann::json& j, const contact_book& cb)
 {
     j = json{{"name", cb.m_book_name}, {"contacts", cb.m_contacts}};
 }

 // operators
 static bool operator==(age lhs, age rhs)
 {
     return lhs.m_val == rhs.m_val;
 }

 static bool operator==(const address& lhs, const address& rhs)
 {
     return lhs.m_val == rhs.m_val;
 }

 static bool operator==(const name& lhs, const name& rhs)
 {
     return lhs.m_val == rhs.m_val;
 }

 static bool operator==(const person& lhs, const person& rhs)
 {
     return std::tie(lhs.m_name, lhs.m_age) == std::tie(rhs.m_name, rhs.m_age);
 }

 static bool operator==(const contact& lhs, const contact& rhs)
 {
     return std::tie(lhs.m_person, lhs.m_address) ==
            std::tie(rhs.m_person, rhs.m_address);
 }

 static bool operator==(const contact_book& lhs, const contact_book& rhs)
 {
     return std::tie(lhs.m_book_name, lhs.m_contacts) ==
            std::tie(rhs.m_book_name, rhs.m_contacts);
 }
 }

 // from_json methods
 namespace udt
 {
 template <typename BasicJsonType>
 static void from_json(const BasicJsonType& j, age& a)
 {
     a.m_val = j.template get<int>();
 }

 template <typename BasicJsonType>
 static void from_json(const BasicJsonType& j, name& n)
 {
     n.m_val = j.template get<std::string>();
 }

 template <typename BasicJsonType>
 static void from_json(const BasicJsonType& j, country& c)
 {
     const auto str = j.template get<std::string>();
     static const std::map<std::string, country> m =
     {
         {u8"中华人民共和国", country::china},
         {"France", country::france},
         {u8"Российская Федерация", country::russia}
     };

     const auto it = m.find(str);
     // TODO test exceptions
     c = it->second;
 }

 template <typename BasicJsonType>
 static void from_json(const BasicJsonType& j, person& p)
 {
     p.m_age = j["age"].template get<age>();
     p.m_name = j["name"].template get<name>();
     p.m_country = j["country"].template get<country>();
 }

 static void from_json(const nlohmann::json& j, address& a)
 {
     a.m_val = j.get<std::string>();
 }

 static void from_json(const nlohmann::json& j, contact& c)
 {
     c.m_person = j["person"].get<person>();
     c.m_address = j["address"].get<address>();
 }

 static void from_json(const nlohmann::json& j, contact_book& cb)
 {
     cb.m_book_name = j["name"].get<name>();
     cb.m_contacts = j["contacts"].get<std::vector<contact>>();
 }
 }

 TEST_CASE("basic usage" * doctest::test_suite("udt"))
 {

     // a bit narcissistic maybe :) ?
     const udt::age a
     {
         23
     };
     const udt::name n{"theo"};
     const udt::country c{udt::country::france};
     const udt::person sfinae_addict{a, n, c};
     const udt::person senior_programmer{{42}, {u8"王芳"}, udt::country::china};
     const udt::address addr{"Paris"};
     const udt::contact cpp_programmer{sfinae_addict, addr};
     const udt::contact_book book{{"C++"}, {cpp_programmer, {senior_programmer, addr}}};

     SECTION("conversion to json via free-functions")
     {
         CHECK(json(a) == json(23));
         CHECK(json(n) == json("theo"));
         CHECK(json(c) == json("France"));
         CHECK(json(sfinae_addict) == R"({"name":"theo", "age":23, "country":"France"})"_json);
         CHECK(json("Paris") == json(addr));
         CHECK(json(cpp_programmer) ==
               R"({"person" : {"age":23, "name":"theo", "country":"France"}, "address":"Paris"})"_json);

         CHECK(
             json(book) ==
             u8R"({"name":"C++", "contacts" : [{"person" : {"age":23, "name":"theo", "country":"France"}, "address":"Paris"}, {"person" : {"age":42, "country":"中华人民共和国", "name":"王芳"}, "address":"Paris"}]})"_json);

     }

     SECTION("conversion from json via free-functions")
     {
         const auto big_json =
             u8R"({"name":"C++", "contacts" : [{"person" : {"age":23, "name":"theo", "country":"France"}, "address":"Paris"}, {"person" : {"age":42, "country":"中华人民共和国", "name":"王芳"}, "address":"Paris"}]})"_json;
         SECTION("via explicit calls to get")
         {
             const auto parsed_book = big_json.get<udt::contact_book>();
             const auto book_name = big_json["name"].get<udt::name>();
             const auto contacts =
                 big_json["contacts"].get<std::vector<udt::contact>>();
             const auto contact_json = big_json["contacts"].at(0);
             const auto contact = contact_json.get<udt::contact>();
             const auto person = contact_json["person"].get<udt::person>();
             const auto address = contact_json["address"].get<udt::address>();
             const auto age = contact_json["person"]["age"].get<udt::age>();
             const auto country =
                 contact_json["person"]["country"].get<udt::country>();
             const auto name = contact_json["person"]["name"].get<udt::name>();

             CHECK(age == a);
             CHECK(name == n);
             CHECK(country == c);
             CHECK(address == addr);
             CHECK(person == sfinae_addict);
             CHECK(contact == cpp_programmer);
             CHECK(contacts == book.m_contacts);
             CHECK(book_name == udt::name{"C++"});
             CHECK(book == parsed_book);
         }

         SECTION("via explicit calls to get_to")
         {
             udt::person person;
             udt::name name;

             json person_json = big_json["contacts"][0]["person"];
             CHECK(person_json.get_to(person) == sfinae_addict);

             // correct reference gets returned
             person_json["name"].get_to(name).m_val = "new name";
             CHECK(name.m_val == "new name");
         }

         SECTION("implicit conversions")
         {
             const udt::contact_book parsed_book = big_json;
             const udt::name book_name = big_json["name"];
             const std::vector<udt::contact> contacts = big_json["contacts"];
             const auto contact_json = big_json["contacts"].at(0);
             const udt::contact contact = contact_json;
             const udt::person person = contact_json["person"];
             const udt::address address = contact_json["address"];
             const udt::age age = contact_json["person"]["age"];
             const udt::country country = contact_json["person"]["country"];
             const udt::name name = contact_json["person"]["name"];

             CHECK(age == a);
             CHECK(name == n);
             CHECK(country == c);
             CHECK(address == addr);
             CHECK(person == sfinae_addict);
             CHECK(contact == cpp_programmer);
             CHECK(contacts == book.m_contacts);
             CHECK(book_name == udt::name{"C++"});
             CHECK(book == parsed_book);
         }
     }
 }

 namespace udt
 {
 struct legacy_type
 {
     std::string number;
     legacy_type() : number() {}
     legacy_type(const std::string& n) : number(n) {}
 };
 }

 namespace nlohmann
 {
 template <typename T>
 struct adl_serializer<std::shared_ptr<T>>
 {
     static void to_json(json& j, const std::shared_ptr<T>& opt)
     {
         if (opt)
         {
             j = *opt;
         }
         else
         {
             j = nullptr;
         }
     }

     static void from_json(const json& j, std::shared_ptr<T>& opt)
     {
         if (j.is_null())
         {
             opt = nullptr;
         }
         else
         {
             opt.reset(new T(j.get<T>()));
         }
     }
 };

 template <>
 struct adl_serializer<udt::legacy_type>
 {
     static void to_json(json& j, const udt::legacy_type& l)
     {
         j = std::stoi(l.number);
     }

     static void from_json(const json& j, udt::legacy_type& l)
     {
         l.number = std::to_string(j.get<int>());
     }
 };
 }

 TEST_CASE("adl_serializer specialization" * doctest::test_suite("udt"))
 {
     SECTION("partial specialization")
     {
         SECTION("to_json")
         {
             std::shared_ptr<udt::person> optPerson;

             json j = optPerson;
             CHECK(j.is_null());

             optPerson.reset(new udt::person{{42}, {"John Doe"}, udt::country::russia});
             j = optPerson;
             CHECK_FALSE(j.is_null());

             CHECK(j.get<udt::person>() == *optPerson);
         }

         SECTION("from_json")
         {
             auto person = udt::person{{42}, {"John Doe"}, udt::country::russia};
             json j = person;

             auto optPerson = j.get<std::shared_ptr<udt::person>>();
             REQUIRE(optPerson);
             CHECK(*optPerson == person);

             j = nullptr;
             optPerson = j.get<std::shared_ptr<udt::person>>();
             CHECK(!optPerson);
         }
     }

     SECTION("total specialization")
     {
         SECTION("to_json")
         {
             udt::legacy_type lt{"4242"};

             json j = lt;
             CHECK(j.get<int>() == 4242);
         }

         SECTION("from_json")
         {
             json j = 4242;
             auto lt = j.get<udt::legacy_type>();
             CHECK(lt.number == "4242");
         }
     }
 }

 namespace nlohmann
 {
 template <>
 struct adl_serializer<std::vector<float>>
 {
     using type = std::vector<float>;
     static void to_json(json& j, const type&)
     {
         j = "hijacked!";
     }

     static void from_json(const json&, type& opt)
     {
         opt = {42.0, 42.0, 42.0};
     }

     // preferred version
     static type from_json(const json&)
     {
         return {4.0, 5.0, 6.0};
     }
 };
 }

 TEST_CASE("even supported types can be specialized" * doctest::test_suite("udt"))
 {
     json j = std::vector<float> {1.0, 2.0, 3.0};
     CHECK(j.dump() == R"("hijacked!")");
     auto f = j.get<std::vector<float>>();
     // the single argument from_json method is preferred
     CHECK((f == std::vector<float> {4.0, 5.0, 6.0}));
 }

 namespace nlohmann
 {
 template <typename T>
 struct adl_serializer<std::unique_ptr<T>>
 {
     static void to_json(json& j, const std::unique_ptr<T>& opt)
     {
         if (opt)
         {
             j = *opt;
         }
         else
         {
             j = nullptr;
         }
     }

     // this is the overload needed for non-copyable types,
     static std::unique_ptr<T> from_json(const json& j)
     {
         if (j.is_null())
         {
             return nullptr;
         }
         else
         {
             return std::unique_ptr<T>(new T(j.get<T>()));
         }
     }
 };
 }

 TEST_CASE("Non-copyable types" * doctest::test_suite("udt"))
 {
     SECTION("to_json")
     {
         std::unique_ptr<udt::person> optPerson;

         json j = optPerson;
         CHECK(j.is_null());

         optPerson.reset(new udt::person{{42}, {"John Doe"}, udt::country::russia});
         j = optPerson;
         CHECK_FALSE(j.is_null());

         CHECK(j.get<udt::person>() == *optPerson);
     }

     SECTION("from_json")
     {
         auto person = udt::person{{42}, {"John Doe"}, udt::country::russia};
         json j = person;

         auto optPerson = j.get<std::unique_ptr<udt::person>>();
         REQUIRE(optPerson);
         CHECK(*optPerson == person);

         j = nullptr;
         optPerson = j.get<std::unique_ptr<udt::person>>();
         CHECK(!optPerson);
     }
 }

 // custom serializer - advanced usage
 // pack structs that are pod-types (but not scalar types)
 // relies on adl for any other type
 template <typename T, typename = void>
 struct pod_serializer
 {
     // use adl for non-pods, or scalar types
     template <
         typename BasicJsonType, typename U = T,
         typename std::enable_if <
             !(std::is_pod<U>::value && std::is_class<U>::value), int >::type = 0 >
     static void from_json(const BasicJsonType& j, U& t)
     {
         using nlohmann::from_json;
         from_json(j, t);
     }

     // special behaviour for pods
     template < typename BasicJsonType, typename U = T,
                typename std::enable_if <
                    std::is_pod<U>::value && std::is_class<U>::value, int >::type = 0 >
     static void from_json(const  BasicJsonType& j, U& t)
     {
         std::uint64_t value;
         // TODO The following block is no longer relevant in this serializer, make another one that shows the issue
         // the problem arises only when one from_json method is defined without any constraint
         //
         // Why cannot we simply use: j.get<std::uint64_t>() ?
         // Well, with the current experiment, the get method looks for a from_json
         // function, which we are currently defining!
         // This would end up in a stack overflow. Calling nlohmann::from_json is a
         // workaround (is it?).
         // I shall find a good way to avoid this once all constructors are converted
         // to free methods
         //
         // In short, constructing a json by constructor calls to_json
         // calling get calls from_json, for now, we cannot do this in custom
         // serializers
         nlohmann::from_json(j, value);
         auto bytes = static_cast<char*>(static_cast<void*>(&value));
         std::memcpy(&t, bytes, sizeof(value));
     }

     template <
         typename BasicJsonType, typename U = T,
         typename std::enable_if <
             !(std::is_pod<U>::value && std::is_class<U>::value), int >::type = 0 >
     static void to_json(BasicJsonType& j, const  T& t)
     {
         using nlohmann::to_json;
         to_json(j, t);
     }

     template < typename BasicJsonType, typename U = T,
                typename std::enable_if <
                    std::is_pod<U>::value && std::is_class<U>::value, int >::type = 0 >
     static void to_json(BasicJsonType& j, const  T& t) noexcept
     {
         auto bytes = static_cast< const unsigned char*>(static_cast<const void*>(&t));
         std::uint64_t value;
         std::memcpy(&value, bytes, sizeof(value));
         nlohmann::to_json(j, value);
     }
 };

 namespace udt
 {
 struct small_pod
 {
     int begin;
     char middle;
     short end;
 };

 struct non_pod
 {
     std::string s;
     non_pod() : s() {}
     non_pod(const std::string& S) : s(S) {}
 };

 template <typename BasicJsonType>
 static void to_json(BasicJsonType& j, const non_pod& np)
 {
     j = np.s;
 }

 template <typename BasicJsonType>
 static void from_json(const BasicJsonType& j, non_pod& np)
 {
     np.s = j.template get<std::string>();
 }

 static bool operator==(small_pod lhs, small_pod rhs) noexcept
 {
     return std::tie(lhs.begin, lhs.middle, lhs.end) ==
            std::tie(rhs.begin, rhs.middle, rhs.end);
 }

 static bool operator==(const  non_pod& lhs, const  non_pod& rhs) noexcept
 {
     return lhs.s == rhs.s;
 }

 static std::ostream& operator<<(std::ostream& os, small_pod l)
 {
     return os << "begin: " << l.begin << ", middle: " << l.middle << ", end: " << l.end;
 }
 }

 TEST_CASE("custom serializer for pods" * doctest::test_suite("udt"))
 {
     using custom_json =
         nlohmann::basic_json<std::map, std::vector, std::string, bool,
         std::int64_t, std::uint64_t, double, std::allocator, pod_serializer>;

     auto p = udt::small_pod{42, '/', 42};
     custom_json j = p;

     auto p2 = j.get<udt::small_pod>();

     CHECK(p == p2);

     auto np = udt::non_pod{{"non-pod"}};
     custom_json j2 = np;
     auto np2 = j2.get<udt::non_pod>();
     CHECK(np == np2);
 }

 template <typename T, typename>
 struct another_adl_serializer;

 using custom_json = nlohmann::basic_json<std::map, std::vector, std::string, bool, std::int64_t, std::uint64_t, double, std::allocator, another_adl_serializer>;

 template <typename T, typename>
 struct another_adl_serializer
 {
     static void from_json(const custom_json& j, T& t)
     {
         using nlohmann::from_json;
         from_json(j, t);
     }

     static void to_json(custom_json& j, const T& t)
     {
         using nlohmann::to_json;
         to_json(j, t);
     }
 };

 TEST_CASE("custom serializer that does adl by default" * doctest::test_suite("udt"))
 {
     auto me = udt::person{{23}, {"theo"}, udt::country::france};

     json j = me;
     custom_json cj = me;

     CHECK(j.dump() == cj.dump());

     CHECK(me == j.get<udt::person>());
     CHECK(me == cj.get<udt::person>());
 }

 TEST_CASE("different basic_json types conversions")
 {
     SECTION("null")
     {
         json j;
         custom_json cj = j;
         CHECK(cj == nullptr);
     }

     SECTION("boolean")
     {
         json j = true;
         custom_json cj = j;
         CHECK(cj == true);
     }

     SECTION("discarded")
     {
         json j(json::value_t::discarded);
         custom_json cj;
         CHECK_NOTHROW(cj = j);
         CHECK(cj.type() == custom_json::value_t::discarded);
     }

     SECTION("array")
     {
         json j = {1, 2, 3};
         custom_json cj = j;
         CHECK((cj == std::vector<int> {1, 2, 3}));
     }

     SECTION("integer")
     {
         json j = 42;
         custom_json cj = j;
         CHECK(cj == 42);
     }

     SECTION("float")
     {
         json j = 42.0;
         custom_json cj = j;
         CHECK(cj == 42.0);
     }

     SECTION("unsigned")
     {
         json j = 42u;
         custom_json cj = j;
         CHECK(cj == 42u);
     }

     SECTION("string")
     {
         json j = "forty-two";
         custom_json cj = j;
         CHECK(cj == "forty-two");
     }

     SECTION("binary")
     {
         json j = json::binary({1, 2, 3}, 42);
         custom_json cj = j;
         CHECK(cj.get_binary().subtype() == 42);
         std::vector<std::uint8_t> cv = cj.get_binary();
         std::vector<std::uint8_t> v = j.get_binary();
         CHECK(cv == v);
     }

     SECTION("object")
     {
         json j = {{"forty", "two"}};
         custom_json cj = j;
         auto m = j.get<std::map<std::string, std::string>>();
         CHECK(cj == m);
     }

     SECTION("get<custom_json>")
     {
         json j = 42;
         custom_json cj = j.get<custom_json>();
         CHECK(cj == 42);
     }
 }

 namespace
 {
 struct incomplete;

 // std::is_constructible is broken on macOS' libc++
 // use the cppreference implementation

 template <typename T, typename = void>
 struct is_constructible_patched : std::false_type {};

 template <typename T>
 struct is_constructible_patched<T, decltype(void(json(std::declval<T>())))> : std::true_type {};
 }

 TEST_CASE("an incomplete type does not trigger a compiler error in non-evaluated context" * doctest::test_suite("udt"))
 {
     static_assert(!is_constructible_patched<json, incomplete>::value, "");
 }

 namespace
 {
 class Evil
 {
   public:
     Evil() = default;
     template <typename T>
     Evil(T t) : m_i(sizeof(t)) {}

     int m_i = 0;
 };

 void from_json(const json&, Evil&) {}
 }

 TEST_CASE("Issue #924")
 {
     // Prevent get<std::vector<Evil>>() to throw
     auto j = json::array();

     CHECK_NOTHROW(j.get<Evil>());
     CHECK_NOTHROW(j.get<std::vector<Evil>>());

     // silence Wunused-template warnings
     Evil e(1);
     CHECK(e.m_i >= 0);
 }

 TEST_CASE("Issue #1237")
 {
     struct non_convertible_type {};
     static_assert(!std::is_convertible<json, non_convertible_type>::value, "");
 }
	/*
	__ _____ _____ _____
	__\| \| __\| \| \| \| JSON for Modern C++ (test suite)
	\| \| \|__ \| \| \| \| \| \| version 3.8.0
	\|_____\|_____\|_____\|_\|___\| https://github.com/nlohmann/json

	Licensed under the MIT License <http://opensource.org/licenses/MIT>.
	SPDX-License-Identifier: MIT
	Copyright (c) 2013-2019 Niels Lohmann <http://nlohmann.me>.

	Permission is hereby granted, free of charge, to any person obtaining a copy
	of this software and associated documentation files (the "Software"), to deal
	in the Software without restriction, including without limitation the rights
	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	copies of the Software, and to permit persons to whom the Software is
	furnished to do so, subject to the following conditions:

	The above copyright notice and this permission notice shall be included in all
	copies or substantial portions of the Software.

	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
	SOFTWARE.
	*/

	#include "doctest_compatibility.h"

	#include <nlohmann/json.hpp>
	using nlohmann::json;

	#include <array>
	#include <map>
	#include <string>
	#include <memory>

	namespace udt
	{
	enum class country
	{
	china,
	france,
	russia
	};

	struct age
	{
	int m_val;
	age(int rhs = 0) : m_val(rhs) {}
	};

	struct name
	{
	std::string m_val;
	name(const std::string rhs = "") : m_val(rhs) {}
	};

	struct address
	{
	std::string m_val;
	address(const std::string rhs = "") : m_val(rhs) {}
	};

	struct person
	{
	age m_age;
	name m_name;
	country m_country;
	person() : m_age(), m_name(), m_country() {}
	person(const age& a, const name& n, const country& c) : m_age(a), m_name(n), m_country(c) {}
	};

	struct contact
	{
	person m_person;
	address m_address;
	contact() : m_person(), m_address() {}
	contact(const person& p, const address& a) : m_person(p), m_address(a) {}
	};

	struct contact_book
	{
	name m_book_name;
	std::vector<contact> m_contacts;
	contact_book() : m_book_name(), m_contacts() {}
	contact_book(const name& n, const std::vector<contact>& c) : m_book_name(n), m_contacts(c) {}
	};
	}

	// to_json methods
	namespace udt
	{
	// templates because of the custom_json tests (see below)
	template <typename BasicJsonType>
	static void to_json(BasicJsonType& j, age a)
	{
	j = a.m_val;
	}

	template <typename BasicJsonType>
	static void to_json(BasicJsonType& j, const name& n)
	{
	j = n.m_val;
	}

	template <typename BasicJsonType>
	static void to_json(BasicJsonType& j, country c)
	{
	switch (c)
	{
	case country::china:
	j = u8"中华人民共和国";
	return;
	case country::france:
	j = "France";
	return;
	case country::russia:
	j = u8"Российская Федерация";
	return;
	default:
	break;
	}
	}

	template <typename BasicJsonType>
	static void to_json(BasicJsonType& j, const person& p)
	{
	j = BasicJsonType{{"age", p.m_age}, {"name", p.m_name}, {"country", p.m_country}};
	}

	static void to_json(nlohmann::json& j, const address& a)
	{
	j = a.m_val;
	}

	static void to_json(nlohmann::json& j, const contact& c)
	{
	j = json{{"person", c.m_person}, {"address", c.m_address}};
	}

	static void to_json(nlohmann::json& j, const contact_book& cb)
	{
	j = json{{"name", cb.m_book_name}, {"contacts", cb.m_contacts}};
	}

	// operators
	static bool operator==(age lhs, age rhs)
	{
	return lhs.m_val == rhs.m_val;
	}

	static bool operator==(const address& lhs, const address& rhs)
	{
	return lhs.m_val == rhs.m_val;
	}

	static bool operator==(const name& lhs, const name& rhs)
	{
	return lhs.m_val == rhs.m_val;
	}

	static bool operator==(const person& lhs, const person& rhs)
	{
	return std::tie(lhs.m_name, lhs.m_age) == std::tie(rhs.m_name, rhs.m_age);
	}

	static bool operator==(const contact& lhs, const contact& rhs)
	{
	return std::tie(lhs.m_person, lhs.m_address) ==
	std::tie(rhs.m_person, rhs.m_address);
	}

	static bool operator==(const contact_book& lhs, const contact_book& rhs)
	{
	return std::tie(lhs.m_book_name, lhs.m_contacts) ==
	std::tie(rhs.m_book_name, rhs.m_contacts);
	}
	}

	// from_json methods
	namespace udt
	{
	template <typename BasicJsonType>
	static void from_json(const BasicJsonType& j, age& a)
	{
	a.m_val = j.template get<int>();
	}

	template <typename BasicJsonType>
	static void from_json(const BasicJsonType& j, name& n)
	{
	n.m_val = j.template get<std::string>();
	}

	template <typename BasicJsonType>
	static void from_json(const BasicJsonType& j, country& c)
	{
	const auto str = j.template get<std::string>();
	static const std::map<std::string, country> m =
	{
	{u8"中华人民共和国", country::china},
	{"France", country::france},
	{u8"Российская Федерация", country::russia}
	};

	const auto it = m.find(str);
	// TODO test exceptions
	c = it->second;
	}

	template <typename BasicJsonType>
	static void from_json(const BasicJsonType& j, person& p)
	{
	p.m_age = j["age"].template get<age>();
	p.m_name = j["name"].template get<name>();
	p.m_country = j["country"].template get<country>();
	}

	static void from_json(const nlohmann::json& j, address& a)
	{
	a.m_val = j.get<std::string>();
	}

	static void from_json(const nlohmann::json& j, contact& c)
	{
	c.m_person = j["person"].get<person>();
	c.m_address = j["address"].get<address>();
	}

	static void from_json(const nlohmann::json& j, contact_book& cb)
	{
	cb.m_book_name = j["name"].get<name>();
	cb.m_contacts = j["contacts"].get<std::vector<contact>>();
	}
	}

	TEST_CASE("basic usage" * doctest::test_suite("udt"))
	{

	// a bit narcissistic maybe :) ?
	const udt::age a
	{
	23
	};
	const udt::name n{"theo"};
	const udt::country c{udt::country::france};
	const udt::person sfinae_addict{a, n, c};
	const udt::person senior_programmer{{42}, {u8"王芳"}, udt::country::china};
	const udt::address addr{"Paris"};
	const udt::contact cpp_programmer{sfinae_addict, addr};
	const udt::contact_book book{{"C++"}, {cpp_programmer, {senior_programmer, addr}}};

	SECTION("conversion to json via free-functions")
	{
	CHECK(json(a) == json(23));
	CHECK(json(n) == json("theo"));
	CHECK(json(c) == json("France"));
	CHECK(json(sfinae_addict) == R"({"name":"theo", "age":23, "country":"France"})"_json);
	CHECK(json("Paris") == json(addr));
	CHECK(json(cpp_programmer) ==
	R"({"person" : {"age":23, "name":"theo", "country":"France"}, "address":"Paris"})"_json);

	CHECK(
	json(book) ==
	u8R"({"name":"C++", "contacts" : [{"person" : {"age":23, "name":"theo", "country":"France"}, "address":"Paris"}, {"person" : {"age":42, "country":"中华人民共和国", "name":"王芳"}, "address":"Paris"}]})"_json);

	}

	SECTION("conversion from json via free-functions")
	{
	const auto big_json =
	u8R"({"name":"C++", "contacts" : [{"person" : {"age":23, "name":"theo", "country":"France"}, "address":"Paris"}, {"person" : {"age":42, "country":"中华人民共和国", "name":"王芳"}, "address":"Paris"}]})"_json;
	SECTION("via explicit calls to get")
	{
	const auto parsed_book = big_json.get<udt::contact_book>();
	const auto book_name = big_json["name"].get<udt::name>();
	const auto contacts =
	big_json["contacts"].get<std::vector<udt::contact>>();
	const auto contact_json = big_json["contacts"].at(0);
	const auto contact = contact_json.get<udt::contact>();
	const auto person = contact_json["person"].get<udt::person>();
	const auto address = contact_json["address"].get<udt::address>();
	const auto age = contact_json["person"]["age"].get<udt::age>();
	const auto country =
	contact_json["person"]["country"].get<udt::country>();
	const auto name = contact_json["person"]["name"].get<udt::name>();

	CHECK(age == a);
	CHECK(name == n);
	CHECK(country == c);
	CHECK(address == addr);
	CHECK(person == sfinae_addict);
	CHECK(contact == cpp_programmer);
	CHECK(contacts == book.m_contacts);
	CHECK(book_name == udt::name{"C++"});
	CHECK(book == parsed_book);
	}

	SECTION("via explicit calls to get_to")
	{
	udt::person person;
	udt::name name;

	json person_json = big_json["contacts"][0]["person"];
	CHECK(person_json.get_to(person) == sfinae_addict);

	// correct reference gets returned
	person_json["name"].get_to(name).m_val = "new name";
	CHECK(name.m_val == "new name");
	}

	SECTION("implicit conversions")
	{
	const udt::contact_book parsed_book = big_json;
	const udt::name book_name = big_json["name"];
	const std::vector<udt::contact> contacts = big_json["contacts"];
	const auto contact_json = big_json["contacts"].at(0);
	const udt::contact contact = contact_json;
	const udt::person person = contact_json["person"];
	const udt::address address = contact_json["address"];
	const udt::age age = contact_json["person"]["age"];
	const udt::country country = contact_json["person"]["country"];
	const udt::name name = contact_json["person"]["name"];

	CHECK(age == a);
	CHECK(name == n);
	CHECK(country == c);
	CHECK(address == addr);
	CHECK(person == sfinae_addict);
	CHECK(contact == cpp_programmer);
	CHECK(contacts == book.m_contacts);
	CHECK(book_name == udt::name{"C++"});
	CHECK(book == parsed_book);
	}
	}
	}

	namespace udt
	{
	struct legacy_type
	{
	std::string number;
	legacy_type() : number() {}
	legacy_type(const std::string& n) : number(n) {}
	};
	}

	namespace nlohmann
	{
	template <typename T>
	struct adl_serializer<std::shared_ptr<T>>
	{
	static void to_json(json& j, const std::shared_ptr<T>& opt)
	{
	if (opt)
	{
	j = *opt;
	}
	else
	{
	j = nullptr;
	}
	}

	static void from_json(const json& j, std::shared_ptr<T>& opt)
	{
	if (j.is_null())
	{
	opt = nullptr;
	}
	else
	{
	opt.reset(new T(j.get<T>()));
	}
	}
	};

	template <>
	struct adl_serializer<udt::legacy_type>
	{
	static void to_json(json& j, const udt::legacy_type& l)
	{
	j = std::stoi(l.number);
	}

	static void from_json(const json& j, udt::legacy_type& l)
	{
	l.number = std::to_string(j.get<int>());
	}
	};
	}

	TEST_CASE("adl_serializer specialization" * doctest::test_suite("udt"))
	{
	SECTION("partial specialization")
	{
	SECTION("to_json")
	{
	std::shared_ptr<udt::person> optPerson;

	json j = optPerson;
	CHECK(j.is_null());

	optPerson.reset(new udt::person{{42}, {"John Doe"}, udt::country::russia});
	j = optPerson;
	CHECK_FALSE(j.is_null());

	CHECK(j.get<udt::person>() == *optPerson);
	}

	SECTION("from_json")
	{
	auto person = udt::person{{42}, {"John Doe"}, udt::country::russia};
	json j = person;

	auto optPerson = j.get<std::shared_ptr<udt::person>>();
	REQUIRE(optPerson);
	CHECK(*optPerson == person);

	j = nullptr;
	optPerson = j.get<std::shared_ptr<udt::person>>();
	CHECK(!optPerson);
	}
	}

	SECTION("total specialization")
	{
	SECTION("to_json")
	{
	udt::legacy_type lt{"4242"};

	json j = lt;
	CHECK(j.get<int>() == 4242);
	}

	SECTION("from_json")
	{
	json j = 4242;
	auto lt = j.get<udt::legacy_type>();
	CHECK(lt.number == "4242");
	}
	}
	}

	namespace nlohmann
	{
	template <>
	struct adl_serializer<std::vector<float>>
	{
	using type = std::vector<float>;
	static void to_json(json& j, const type&)
	{
	j = "hijacked!";
	}

	static void from_json(const json&, type& opt)
	{
	opt = {42.0, 42.0, 42.0};
	}

	// preferred version
	static type from_json(const json&)
	{
	return {4.0, 5.0, 6.0};
	}
	};
	}

	TEST_CASE("even supported types can be specialized" * doctest::test_suite("udt"))
	{
	json j = std::vector<float> {1.0, 2.0, 3.0};
	CHECK(j.dump() == R"("hijacked!")");
	auto f = j.get<std::vector<float>>();
	// the single argument from_json method is preferred
	CHECK((f == std::vector<float> {4.0, 5.0, 6.0}));
	}

	namespace nlohmann
	{
	template <typename T>
	struct adl_serializer<std::unique_ptr<T>>
	{
	static void to_json(json& j, const std::unique_ptr<T>& opt)
	{
	if (opt)
	{
	j = *opt;
	}
	else
	{
	j = nullptr;
	}
	}

	// this is the overload needed for non-copyable types,
	static std::unique_ptr<T> from_json(const json& j)
	{
	if (j.is_null())
	{
	return nullptr;
	}
	else
	{
	return std::unique_ptr<T>(new T(j.get<T>()));
	}
	}
	};
	}

	TEST_CASE("Non-copyable types" * doctest::test_suite("udt"))
	{
	SECTION("to_json")
	{
	std::unique_ptr<udt::person> optPerson;

	json j = optPerson;
	CHECK(j.is_null());

	optPerson.reset(new udt::person{{42}, {"John Doe"}, udt::country::russia});
	j = optPerson;
	CHECK_FALSE(j.is_null());

	CHECK(j.get<udt::person>() == *optPerson);
	}

	SECTION("from_json")
	{
	auto person = udt::person{{42}, {"John Doe"}, udt::country::russia};
	json j = person;

	auto optPerson = j.get<std::unique_ptr<udt::person>>();
	REQUIRE(optPerson);
	CHECK(*optPerson == person);

	j = nullptr;
	optPerson = j.get<std::unique_ptr<udt::person>>();
	CHECK(!optPerson);
	}
	}

	// custom serializer - advanced usage
	// pack structs that are pod-types (but not scalar types)
	// relies on adl for any other type
	template <typename T, typename = void>
	struct pod_serializer
	{
	// use adl for non-pods, or scalar types
	template <
	typename BasicJsonType, typename U = T,
	typename std::enable_if <
	!(std::is_pod<U>::value && std::is_class<U>::value), int >::type = 0 >
	static void from_json(const BasicJsonType& j, U& t)
	{
	using nlohmann::from_json;
	from_json(j, t);
	}

	// special behaviour for pods
	template < typename BasicJsonType, typename U = T,
	typename std::enable_if <
	std::is_pod<U>::value && std::is_class<U>::value, int >::type = 0 >
	static void from_json(const BasicJsonType& j, U& t)
	{
	std::uint64_t value;
	// TODO The following block is no longer relevant in this serializer, make another one that shows the issue
	// the problem arises only when one from_json method is defined without any constraint
	//
	// Why cannot we simply use: j.get<std::uint64_t>() ?
	// Well, with the current experiment, the get method looks for a from_json
	// function, which we are currently defining!
	// This would end up in a stack overflow. Calling nlohmann::from_json is a
	// workaround (is it?).
	// I shall find a good way to avoid this once all constructors are converted
	// to free methods
	//
	// In short, constructing a json by constructor calls to_json
	// calling get calls from_json, for now, we cannot do this in custom
	// serializers
	nlohmann::from_json(j, value);
	auto bytes = static_cast<char>(static_cast<void>(&value));
	std::memcpy(&t, bytes, sizeof(value));
	}

	template <
	typename BasicJsonType, typename U = T,
	typename std::enable_if <
	!(std::is_pod<U>::value && std::is_class<U>::value), int >::type = 0 >
	static void to_json(BasicJsonType& j, const T& t)
	{
	using nlohmann::to_json;
	to_json(j, t);
	}

	template < typename BasicJsonType, typename U = T,
	typename std::enable_if <
	std::is_pod<U>::value && std::is_class<U>::value, int >::type = 0 >
	static void to_json(BasicJsonType& j, const T& t) noexcept
	{
	auto bytes = static_cast< const unsigned char>(static_cast<const void>(&t));
	std::uint64_t value;
	std::memcpy(&value, bytes, sizeof(value));
	nlohmann::to_json(j, value);
	}
	};

	namespace udt
	{
	struct small_pod
	{
	int begin;
	char middle;
	short end;
	};

	struct non_pod
	{
	std::string s;
	non_pod() : s() {}
	non_pod(const std::string& S) : s(S) {}
	};

	template <typename BasicJsonType>
	static void to_json(BasicJsonType& j, const non_pod& np)
	{
	j = np.s;
	}

	template <typename BasicJsonType>
	static void from_json(const BasicJsonType& j, non_pod& np)
	{
	np.s = j.template get<std::string>();
	}

	static bool operator==(small_pod lhs, small_pod rhs) noexcept
	{
	return std::tie(lhs.begin, lhs.middle, lhs.end) ==
	std::tie(rhs.begin, rhs.middle, rhs.end);
	}

	static bool operator==(const non_pod& lhs, const non_pod& rhs) noexcept
	{
	return lhs.s == rhs.s;
	}

	static std::ostream& operator<<(std::ostream& os, small_pod l)
	{
	return os << "begin: " << l.begin << ", middle: " << l.middle << ", end: " << l.end;
	}
	}

	TEST_CASE("custom serializer for pods" * doctest::test_suite("udt"))
	{
	using custom_json =
	nlohmann::basic_json<std::map, std::vector, std::string, bool,
	std::int64_t, std::uint64_t, double, std::allocator, pod_serializer>;

	auto p = udt::small_pod{42, '/', 42};
	custom_json j = p;

	auto p2 = j.get<udt::small_pod>();

	CHECK(p == p2);

	auto np = udt::non_pod{{"non-pod"}};
	custom_json j2 = np;
	auto np2 = j2.get<udt::non_pod>();
	CHECK(np == np2);
	}

	template <typename T, typename>
	struct another_adl_serializer;

	using custom_json = nlohmann::basic_json<std::map, std::vector, std::string, bool, std::int64_t, std::uint64_t, double, std::allocator, another_adl_serializer>;

	template <typename T, typename>
	struct another_adl_serializer
	{
	static void from_json(const custom_json& j, T& t)
	{
	using nlohmann::from_json;
	from_json(j, t);
	}

	static void to_json(custom_json& j, const T& t)
	{
	using nlohmann::to_json;
	to_json(j, t);
	}
	};

	TEST_CASE("custom serializer that does adl by default" * doctest::test_suite("udt"))
	{
	auto me = udt::person{{23}, {"theo"}, udt::country::france};

	json j = me;
	custom_json cj = me;

	CHECK(j.dump() == cj.dump());

	CHECK(me == j.get<udt::person>());
	CHECK(me == cj.get<udt::person>());
	}

	TEST_CASE("different basic_json types conversions")
	{
	SECTION("null")
	{
	json j;
	custom_json cj = j;
	CHECK(cj == nullptr);
	}

	SECTION("boolean")
	{
	json j = true;
	custom_json cj = j;
	CHECK(cj == true);
	}

	SECTION("discarded")
	{
	json j(json::value_t::discarded);
	custom_json cj;
	CHECK_NOTHROW(cj = j);
	CHECK(cj.type() == custom_json::value_t::discarded);
	}

	SECTION("array")
	{
	json j = {1, 2, 3};
	custom_json cj = j;
	CHECK((cj == std::vector<int> {1, 2, 3}));
	}

	SECTION("integer")
	{
	json j = 42;
	custom_json cj = j;
	CHECK(cj == 42);
	}

	SECTION("float")
	{
	json j = 42.0;
	custom_json cj = j;
	CHECK(cj == 42.0);
	}

	SECTION("unsigned")
	{
	json j = 42u;
	custom_json cj = j;
	CHECK(cj == 42u);
	}

	SECTION("string")
	{
	json j = "forty-two";
	custom_json cj = j;
	CHECK(cj == "forty-two");
	}

	SECTION("binary")
	{
	json j = json::binary({1, 2, 3}, 42);
	custom_json cj = j;
	CHECK(cj.get_binary().subtype() == 42);
	std::vector<std::uint8_t> cv = cj.get_binary();
	std::vector<std::uint8_t> v = j.get_binary();
	CHECK(cv == v);
	}

	SECTION("object")
	{
	json j = {{"forty", "two"}};
	custom_json cj = j;
	auto m = j.get<std::map<std::string, std::string>>();
	CHECK(cj == m);
	}

	SECTION("get<custom_json>")
	{
	json j = 42;
	custom_json cj = j.get<custom_json>();
	CHECK(cj == 42);
	}
	}

	namespace
	{
	struct incomplete;

	// std::is_constructible is broken on macOS' libc++
	// use the cppreference implementation

	template <typename T, typename = void>
	struct is_constructible_patched : std::false_type {};

	template <typename T>
	struct is_constructible_patched<T, decltype(void(json(std::declval<T>())))> : std::true_type {};
	}

	TEST_CASE("an incomplete type does not trigger a compiler error in non-evaluated context" * doctest::test_suite("udt"))
	{
	static_assert(!is_constructible_patched<json, incomplete>::value, "");
	}

	namespace
	{
	class Evil
	{
	public:
	Evil() = default;
	template <typename T>
	Evil(T t) : m_i(sizeof(t)) {}

	int m_i = 0;
	};

	void from_json(const json&, Evil&) {}
	}

	TEST_CASE("Issue #924")
	{
	// Prevent get<std::vector<Evil>>() to throw
	auto j = json::array();

	CHECK_NOTHROW(j.get<Evil>());
	CHECK_NOTHROW(j.get<std::vector<Evil>>());

	// silence Wunused-template warnings
	Evil e(1);
	CHECK(e.m_i >= 0);
	}

	TEST_CASE("Issue #1237")
	{
	struct non_convertible_type {};
	static_assert(!std::is_convertible<json, non_convertible_type>::value, "");
	}