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add support for non-default-constructible udt

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This commit is contained in:
Théo DELRIEU 2016-11-29 13:09:51 +01:00
parent e5999c6c82
commit 60e6f822fa
2 changed files with 162 additions and 463 deletions
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139
src/json.hpp
View file

@ -290,14 +290,32 @@ struct is_compatible_basic_json_type
}; };
// This trait checks if JSONSerializer<T>::from_json exists // This trait checks if JSONSerializer<T>::from_json(json const&, udt&) exists
template <template <typename, typename> class JSONSerializer, typename Json, template <template <typename, typename> class JSONSerializer, typename Json,
typename T> typename T>
struct has_from_json struct has_from_json
{ {
private: private:
template <typename U, typename = decltype(uncvref_t<U>::from_json( // also check the return type of from_json
std::declval<Json>(), std::declval<T &>()))> template <typename U, typename = enable_if_t<std::is_same<void, decltype(uncvref_t<U>::from_json(
std::declval<Json>(), std::declval<T &>()))>::value>>
static int detect(U &&);
static void detect(...);
public:
static constexpr bool value = std::is_integral<decltype(
detect(std::declval<JSONSerializer<T, void>>()))>::value;
};
// This trait checks if JSONSerializer<T>::from_json(json const&) exists
// this overload is used for non-default-constructible user-defined-types
template <template <typename, typename> class JSONSerializer, typename Json,
typename T>
struct has_non_default_from_json
{
private:
template <typename U, typename = enable_if_t<std::is_same<T, decltype(uncvref_t<U>::from_json(std::declval<Json>()))>::value>>
static int detect(U &&); static int detect(U &&);
static void detect(...); static void detect(...);
@ -326,8 +344,8 @@ public:
// those declarations are needed to workaround a MSVC bug related to ADL // those declarations are needed to workaround a MSVC bug related to ADL
// (taken from MSVC-Ranges implementation) // (taken from MSVC-Ranges implementation)
void to_json(); //void to_json();
void from_json(); //void from_json();
struct to_json_fn struct to_json_fn
{ {
@ -2467,57 +2485,63 @@ class basic_json
return *this; return *this;
} }
/*! // this overload is needed, since constructor for udt is explicit
@brief destructor template <typename T, enable_if_t<not detail::is_compatible_basic_json_type<
uncvref_t<T>, basic_json_t>::value and
Destroys the JSON value and frees all allocated memory. detail::has_to_json<JSONSerializer, basic_json_t, uncvref_t<T>>::value>>
reference &operator=(T &&val) noexcept(std::is_nothrow_constructible<basic_json_t, uncvref_t<T>>::value and
@complexity Linear. std::is_nothrow_move_assignable<uncvref_t<T>>::value)
@requirement This function helps `basic_json` satisfying the
[Container](http://en.cppreference.com/w/cpp/concept/Container)
requirements:
- The complexity is linear.
- All stored elements are destroyed and all memory is freed.
@since version 1.0.0
*/
~basic_json()
{ {
assert_invariant(); static_assert(sizeof(T) == 0 , "");
// I'm not sure this a is good practice...
return *this = basic_json_t{std::forward<T>(val)};
}
switch (m_type) /*!
{ @brief destructor
case value_t::object:
{
AllocatorType<object_t> alloc;
alloc.destroy(m_value.object);
alloc.deallocate(m_value.object, 1);
break;
}
case value_t::array: Destroys the JSON value and frees all allocated memory.
{
AllocatorType<array_t> alloc;
alloc.destroy(m_value.array);
alloc.deallocate(m_value.array, 1);
break;
}
case value_t::string: @complexity Linear.
{
AllocatorType<string_t> alloc;
alloc.destroy(m_value.string);
alloc.deallocate(m_value.string, 1);
break;
}
default: @requirement This function helps `basic_json` satisfying the
{ [Container](http://en.cppreference.com/w/cpp/concept/Container)
// all other types need no specific destructor requirements:
break; - The complexity is linear.
} - All stored elements are destroyed and all memory is freed.
}
@since version 1.0.0
*/
~basic_json() {
assert_invariant();
switch (m_type) {
case value_t::object: {
AllocatorType<object_t> alloc;
alloc.destroy(m_value.object);
alloc.deallocate(m_value.object, 1);
break;
}
case value_t::array: {
AllocatorType<array_t> alloc;
alloc.destroy(m_value.array);
alloc.deallocate(m_value.array, 1);
break;
}
case value_t::string: {
AllocatorType<string_t> alloc;
alloc.destroy(m_value.string);
alloc.deallocate(m_value.string, 1);
break;
}
default: {
// all other types need no specific destructor
break;
}
}
} }
/// @} /// @}
@ -3273,6 +3297,19 @@ class basic_json
return ret; return ret;
} }
// This overload is chosen for non-default constructible user-defined-types
template <
typename T,
enable_if_t<not detail::is_compatible_basic_json_type<
T, basic_json_t>::value and
detail::has_non_default_from_json<JSONSerializer, basic_json_t,
T>::value,
short> = 0>
T get() const
{
return JSONSerializer<T>::from_json(*this);
}
/*! /*!
@brief get a pointer value (explicit) @brief get a pointer value (explicit)

486
test/src/unit-udt.cpp
View file

@ -26,443 +26,105 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE. SOFTWARE.
*/ */
#include <array>
#include <string> #include <string>
#include <memory> #include <memory>
#include "catch.hpp" #include "catch.hpp"
#include "json.hpp" #include "json.hpp"
using nlohmann::json;
namespace udt namespace udt
{ {
struct empty_type {}; struct age
struct pod_type {
int a;
char b;
short c;
};
struct bit_more_complex_type {
pod_type a;
pod_type b;
std::string c;
};
// best optional implementation ever
template <typename T>
class optional_type
{
public:
optional_type() = default;
explicit optional_type(T val) : _val(std::make_shared<T>(std::move(val))) {}
explicit operator bool() const noexcept { return _val != nullptr; }
T const &operator*() const { return *_val; }
optional_type& operator=(T const& t)
{ {
_val = std::make_shared<T>(t); int val;
return *this; };
}
private: struct name
std::shared_ptr<T> _val; {
}; std::string val;
};
// free to/from_json functions struct address
{
std::string val;
};
void to_json(json& j, empty_type) struct person
{ {
j = json::object(); age age;
name name;
};
struct contact
{
person person;
address address;
};
struct contact_book
{
name book_name;
std::vector<contact> contacts;
};
} }
void to_json(json& j, pod_type const& p) // to_json methods for default basic_json
{
j = json{{"a", p.a}, {"b", p.b}, {"c", p.c}};
}
void to_json(json& j, bit_more_complex_type const& p)
{
j = json{{"a", json(p.a)}, {"b", json(p.b)}, {"c", p.c}};
}
template <typename T>
void to_json(json& j, optional_type<T> const& opt)
{
if (!opt)
j = nullptr;
else
j = json(*opt);
}
void from_json(json const& j, empty_type& t)
{
assert(j.empty());
t = empty_type{};
}
void from_json(json const&j, pod_type& t)
{
t = {j["a"].get<int>(), j["b"].get<char>(), j["c"].get<short>()};
}
void from_json(json const&j, bit_more_complex_type& t)
{
// relying on json_traits struct here..
t = {j["a"].get<udt::pod_type>(), j["b"].get<udt::pod_type>(),
j["c"].get<std::string>()};
}
template <typename T>
void from_json(json const& j, optional_type<T>& t)
{
if (j.is_null())
t = optional_type<T>{};
else
t = j.get<T>();
}
inline bool operator==(pod_type const& lhs, pod_type const& rhs) noexcept
{
return std::tie(lhs.a, lhs.b, lhs.c) == std::tie(rhs.a, rhs.b, rhs.c);
}
inline bool operator==(bit_more_complex_type const &lhs,
bit_more_complex_type const &rhs) noexcept {
return std::tie(lhs.a, lhs.b, lhs.c) == std::tie(rhs.a, rhs.b, rhs.c);
}
template <typename T>
inline bool operator==(optional_type<T> const& lhs, optional_type<T> const& rhs)
{
if (!lhs && !rhs)
return true;
if (!lhs || !rhs)
return false;
return *lhs == *rhs;
}
}
TEST_CASE("constructors for user-defined types", "[udt]")
{
SECTION("empty type")
{
udt::empty_type const e{};
auto const j = json{e};
auto k = json::object();
CHECK(j == k);
}
SECTION("pod type")
{
auto const e = udt::pod_type{42, 42, 42};
auto j = json{e};
auto k = json{{"a", 42}, {"b", 42}, {"c", 42}};
CHECK(j == k);
}
SECTION("bit more complex type")
{
auto const e =
udt::bit_more_complex_type{{42, 42, 42}, {41, 41, 41}, "forty"};
auto j = json{e};
auto k = json{{"a", {{"a", 42}, {"b", 42}, {"c", 42}}},
{"b", {{"a", 41}, {"b", 41}, {"c", 41}}},
{"c", "forty"}};
CHECK(j == k);
}
SECTION("vector of udt")
{
std::vector<udt::bit_more_complex_type> v;
auto const e =
udt::bit_more_complex_type{{42, 42, 42}, {41, 41, 41}, "forty"};
v.emplace_back(e);
v.emplace_back(e);
v.emplace_back(e);
json j = v;
auto k = json{{"a", {{"a", 42}, {"b", 42}, {"c", 42}}},
{"b", {{"a", 41}, {"b", 41}, {"c", 41}}},
{"c", "forty"}};
auto l = json{k, k, k};
CHECK(j == l);
}
SECTION("optional type") {
SECTION("regular case") {
udt::optional_type<int> u{3};
CHECK(json{u} == json(3));
}
SECTION("nullopt case") {
udt::optional_type<float> v;
CHECK(json{v} == json{});
}
SECTION("optional of json convertible type")
{
auto const e =
udt::bit_more_complex_type{{42, 42, 42}, {41, 41, 41}, "forty"};
udt::optional_type<udt::bit_more_complex_type> o{e};
auto k = json{{"a", {{"a", 42}, {"b", 42}, {"c", 42}}},
{"b", {{"a", 41}, {"b", 41}, {"c", 41}}},
{"c", "forty"}};
CHECK(json{o} == k);
}
SECTION("optional of vector of json convertible type")
{
std::vector<udt::bit_more_complex_type> v;
auto const e =
udt::bit_more_complex_type{{42, 42, 42}, {41, 41, 41}, "forty"};
v.emplace_back(e);
v.emplace_back(e);
v.emplace_back(e);
udt::optional_type<std::vector<udt::bit_more_complex_type>> o{v};
auto k = json{{"a", {{"a", 42}, {"b", 42}, {"c", 42}}},
{"b", {{"a", 41}, {"b", 41}, {"c", 41}}},
{"c", "forty"}};
auto l = json{k, k, k};
CHECK(json{o} == l);
}
}
}
TEST_CASE("get<> for user-defined types", "[udt]")
{
SECTION("pod type")
{
auto const e = udt::pod_type{42, 42, 42};
auto const j = json{{"a", 42}, {"b", 42}, {"c", 42}};
auto const obj = j.get<udt::pod_type>();
CHECK(e == obj);
}
SECTION("bit more complex type")
{
auto const e =
udt::bit_more_complex_type{{42, 42, 42}, {41, 41, 41}, "forty"};
auto const j = json{{"a", {{"a", 42}, {"b", 42}, {"c", 42}}},
{"b", {{"a", 41}, {"b", 41}, {"c", 41}}},
{"c", "forty"}};
auto const obj = j.get<udt::bit_more_complex_type>();
CHECK(e == obj);
}
SECTION("vector of udt")
{
auto const e =
udt::bit_more_complex_type{{42, 42, 42}, {41, 41, 41}, "forty"};
std::vector<udt::bit_more_complex_type> v{e, e, e};
auto const j = json(v);
auto const obj = j.get<decltype(v)>();
CHECK(v == obj);
}
SECTION("optional")
{
SECTION("from null")
{
udt::optional_type<int> o;
json j;
CHECK(j.get<decltype(o)>() == o);
}
SECTION("from value")
{
json j{{"a", 42}, {"b", 42}, {"c", 42}};
auto v = j.get<udt::optional_type<udt::pod_type>>();
auto expected = udt::pod_type{42,42,42};
REQUIRE(v);
CHECK(*v == expected);
}
}
}
TEST_CASE("to_json free function", "[udt]")
{
SECTION("pod_type")
{
auto const e = udt::pod_type{42, 42, 42};
auto const expected = json{{"a", 42}, {"b", 42}, {"c", 42}};
json j;
nlohmann::to_json(j, e);
CHECK(j == expected);
}
SECTION("bit_more_complex_type")
{
auto const e =
udt::bit_more_complex_type{{42, 42, 42}, {41, 41, 41}, "forty"};
auto const expected = json{{"a", {{"a", 42}, {"b", 42}, {"c", 42}}},
{"b", {{"a", 41}, {"b", 41}, {"c", 41}}},
{"c", "forty"}};
json j;
nlohmann::to_json(j, e);
CHECK(j == expected);
}
SECTION("optional_type")
{
SECTION("from null")
{
udt::optional_type<udt::pod_type> o;
json expected;
json j;
nlohmann::to_json(j, o);
CHECK(expected == j);
}
SECTION("from value")
{
udt::optional_type<udt::pod_type> o{{42, 42, 42}};
auto const expected = json{{"a", 42}, {"b", 42}, {"c", 42}};
json j;
nlohmann::to_json(j, o);
CHECK(expected == j);
}
}
}
TEST_CASE("from_json free function", "[udt]")
{
SECTION("pod_type")
{
auto const expected = udt::pod_type{42, 42, 42};
auto const j = json{{"a", 42}, {"b", 42}, {"c", 42}};
udt::pod_type p;
nlohmann::from_json(j, p);
CHECK(p == expected);
}
SECTION("bit_more_complex_type")
{
auto const expected =
udt::bit_more_complex_type{{42, 42, 42}, {41, 41, 41}, "forty"};
auto const j = json{{"a", {{"a", 42}, {"b", 42}, {"c", 42}}},
{"b", {{"a", 41}, {"b", 41}, {"c", 41}}},
{"c", "forty"}};
udt::bit_more_complex_type p;
nlohmann::from_json(j, p);
CHECK(p == expected);
}
SECTION("optional_type")
{
SECTION("from null")
{
udt::optional_type<udt::pod_type> expected;
json j;
udt::optional_type<udt::pod_type> o;
nlohmann::from_json(j, o);
CHECK(expected == o);
}
SECTION("from value")
{
udt::optional_type<udt::pod_type> expected{{42, 42, 42}};
auto const j = json{{"a", 42}, {"b", 42}, {"c", 42}};
udt::optional_type<udt::pod_type> o;
nlohmann::from_json(j, o);
CHECK(expected == o);
}
}
}
// custom serializer, uses adl by default
template <typename T, typename = void>
struct my_serializer
{
template <typename Json>
static void from_json(Json const& j, T& val)
{
nlohmann::from_json(j, val);
}
template <typename Json>
static void to_json(Json& j, T const& val)
{
nlohmann::to_json(j, val);
}
};
// partial specialization on optional_type
template <typename T>
struct my_serializer<udt::optional_type<T>>
{
template <typename Json>
static void from_json(Json const& j, udt::optional_type<T>& opt)
{
if (j.is_null())
opt = nullptr;
else
opt = j.get<T>();
}
template <typename Json>
static void to_json(Json& j, udt::optional_type<T> const& opt)
{
if (opt)
j = *opt;
else
j = nullptr;
}
};
using my_json = nlohmann::basic_json<std::map, std::vector, std::string, bool,
std::int64_t, std::uint64_t, double,
std::allocator, my_serializer>;
namespace udt namespace udt
{ {
void to_json(my_json& j, pod_type const& val) void to_json(nlohmann::json& j, age a)
{ {
j = my_json{{"a", val.a}, {"b", val.b}, {"c", val.c}}; j = a.val;
} }
void from_json(my_json const& j, pod_type& val) void to_json(nlohmann::json& j, name const& n)
{ {
val = {j["a"].get<int>(), j["b"].get<char>(), j["c"].get<short>()}; j = n.val;
}
void to_json(nlohmann::json& j, person const& p)
{
using nlohmann::json;
j = json{{"age", json{p.age}}, {"name", json{p.name}}};
// this unfortunately does not compile ...
// j["age"] = p.age;
// j["name"] = p.name;
}
void to_json(nlohmann::json& j, address const& a)
{
j = a.val;
}
void to_json(nlohmann::json& j, contact const& c)
{
using nlohmann::json;
j = json{{"person", json{c.person}}, {"address", json{c.address}}};
}
void to_json(nlohmann::json& j, contact_book const& cb)
{
using nlohmann::json;
j = json{{"name", json{cb.book_name}}, {"contacts", cb.contacts}};
} }
} }
TEST_CASE("custom serializer", "[udt]") TEST_CASE("basic usage", "[udt]")
{ {
SECTION("default use works like default serializer") using nlohmann::json;
SECTION("conversion to json via free-functions")
{ {
udt::pod_type pod{1, 2, 3}; udt::age a{23};
auto const j = my_json{pod};
auto const j2 = json{pod}; CHECK(json{a} == json{23});
CHECK(j.dump() == j2.dump());
auto const pod2 = j.get<udt::pod_type>(); // a bit narcissic maybe :) ?
auto const pod3 = j2.get<udt::pod_type>(); udt::name n{"theo"};
CHECK(pod2 == pod3); CHECK(json{n} == json{"theo"});
CHECK(pod2 == pod);
udt::person sfinae_addict{a, n};
CHECK(json{sfinae_addict} == R"({"name":"theo", "age":23})"_json);
} }
}
SECTION("serializer specialization")
{
udt::optional_type<int> opt;
json j{opt};
CHECK(j.is_null());
opt = 42;
j = json{opt};
CHECK(j.get<udt::optional_type<int>>() == opt);
CHECK(42 == j.get<int>());
}
}