mirror/json
1
0
Fork 0
mirror of https://github.com/nlohmann/json.git synced 2025-01-19 15:53:00 +08:00
Code Issues Actions 7 Packages Projects Releases Wiki Activity

replace constructor by from/to_json: array_t

Browse Source 
- tweaked a bit how `get<container<json>>` is handled
- added a from_json overload for forward list
This commit is contained in:
Théo DELRIEU 2017-01-08 16:17:47 +01:00
parent 6d427acdde
commit c847e0eea2
4 changed files with 249 additions and 171 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

196
src/json.hpp
View File

@ -39,6 +39,7 @@ SOFTWARE.
#include <cstdint> // int64_t, uint64_t
#include <cstdlib> // strtod, strtof, strtold, strtoul
#include <cstring> // strlen
#include <forward_list> // forward_list
#include <functional> // function, hash, less
#include <initializer_list> // initializer_list
#include <iomanip> // setw
@ -272,6 +273,32 @@ struct external_constructor<value_t::number_integer>
}
};
template <>
struct external_constructor<value_t::array>
{
template <typename Json>
static void construct(Json &j, const typename Json::array_t& arr)
{
j.m_type = value_t::array;
j.m_value = arr;
j.assert_invariant();
}
template <typename Json, typename CompatibleArrayType,
enable_if_t<not std::is_same<CompatibleArrayType,
typename Json::array_t>::value,
int> = 0>
static void construct(Json &j, const CompatibleArrayType &arr)
{
using std::begin;
using std::end;
j.m_type = value_t::array;
j.m_value.array =
j.template create<typename Json::array_t>(begin(arr), end(arr));
j.assert_invariant();
}
};
// very useful construct against boilerplate (more boilerplate needed than in
// C++17: http://en.cppreference.com/w/cpp/types/void_t)
template <typename...> struct make_void
@ -432,8 +459,6 @@ template <typename T, typename BasicJson>
struct is_compatible_basic_json_type
{
static auto constexpr value =
std::is_same<T, BasicJson>::value or
is_compatible_array_type<BasicJson, T>::value or
is_compatible_object_type<typename BasicJson::object_t, T>::value;
};
@ -575,6 +600,17 @@ void to_json(Json &j, UnscopedEnumType e)
external_constructor<value_t::number_integer>::construct(j, e);
}
template <
typename Json, typename CompatibleArrayType,
enable_if_t<
is_compatible_array_type<Json, CompatibleArrayType>::value or
std::is_same<typename Json::array_t, CompatibleArrayType>::value,
int> = 0>
void to_json(Json &j, CompatibleArrayType const &arr)
{
external_constructor<value_t::array>::construct(j, arr);
}
template <typename Json>
void from_json(Json const& j, typename Json::boolean_t& b)
{
@ -618,6 +654,59 @@ void from_json(Json const &j, UnscopedEnumType& e)
e = static_cast<UnscopedEnumType>(val);
}
template <typename Json>
void from_json(Json const &j, typename Json::array_t &arr)
{
if (!j.is_array())
throw std::domain_error("type must be array, but is " + type_name(j));
arr = *const_cast<Json&>(j).template get_ptr<typename Json::array_t*>();
}
// forward_list doesn't have an insert method, TODO find a way to avoid including forward_list
template <typename Json, typename T, typename Allocator>
void from_json(Json const&j, std::forward_list<T, Allocator>& l)
{
// do not perform the check when user wants to retrieve jsons
// (except when it's null.. ?)
if (j.is_null())
throw std::domain_error("type must be array, but is " + type_name(j));
if (not std::is_same<T, Json>::value)
{
if (!j.is_array())
throw std::domain_error("type must be array, but is " + type_name(j));
}
for (auto it = j.rbegin(), end = j.rend(); it != end; ++it)
l.push_front(it->template get<T>());
}
template <
typename Json, typename CompatibleArrayType,
enable_if_t<is_compatible_array_type<Json, CompatibleArrayType>::value and
not std::is_same<typename Json::array_t,
CompatibleArrayType>::value,
int> = 0>
void from_json(Json const &j, CompatibleArrayType &arr)
{
if (j.is_null())
throw std::domain_error("type must be array, but is " + type_name(j));
// when T == Json, do not check if value_t is correct
if (not std::is_same<typename CompatibleArrayType::value_type, Json>::value)
{
if (!j.is_array())
throw std::domain_error("type must be array, but is " + type_name(j));
}
using std::begin;
using std::end;
std::transform(
j.begin(), j.end(), std::inserter(arr, end(arr)), [](Json const &i)
{
// get<Json>() returns *this, this won't call a from_json method when
// value_type is Json
return i.template get<typename CompatibleArrayType::value_type>();
});
}
// overload for arithmetic types, not chosen for basic_json template arguments (BooleanType, etc..)
//
// note: Is it really necessary to provide explicit overloads for boolean_t etc..
@ -1780,69 +1869,6 @@ class basic_json
assert_invariant();
}
/*!
@brief create an array (explicit)
Create an array JSON value with a given content.
@param[in] val a value for the array
@complexity Linear in the size of the passed @a val.
@throw std::bad_alloc if allocation for array value fails
@liveexample{The following code shows the constructor with an @ref array_t
parameter.,basic_json__array_t}
@sa @ref basic_json(const CompatibleArrayType&) -- create an array value
from a compatible STL containers
@since version 1.0.0
*/
basic_json(const array_t& val)
: m_type(value_t::array), m_value(val)
{
assert_invariant();
}
/*!
@brief create an array (implicit)
Create an array JSON value with a given content. This constructor allows
any type @a CompatibleArrayType that can be used to construct values of
type @ref array_t.
@tparam CompatibleArrayType An object type whose `value_type` is
compatible to @ref array_t. Examples include `std::vector`, `std::deque`,
`std::list`, `std::forward_list`, `std::array`, `std::set`,
`std::unordered_set`, `std::multiset`, and `unordered_multiset` with a
`value_type` from which a @ref basic_json value can be constructed.
@param[in] val a value for the array
@complexity Linear in the size of the passed @a val.
@throw std::bad_alloc if allocation for array value fails
@liveexample{The following code shows the constructor with several
compatible array type parameters.,basic_json__CompatibleArrayType}
@sa @ref basic_json(const array_t&) -- create an array value
@since version 1.0.0
*/
template <class CompatibleArrayType,
enable_if_t<detail::is_compatible_array_type<basic_json_t, CompatibleArrayType>::value,
int> = 0>
basic_json(const CompatibleArrayType& val) : m_type(value_t::array)
{
using std::begin;
using std::end;
m_value.array = create<array_t>(begin(val), end(val));
assert_invariant();
}
// constructor chosen when:
// - JSONSerializer::to_json exists for type T
// - T is not a istream, nor convertible to basic_json (float, vectors, etc)
@ -1851,6 +1877,7 @@ class basic_json
typename T,
enable_if_t<not std::is_base_of<std::istream, uncvref_t<T>>::value and
not detail::is_basic_json_nested_class<uncvref_t<T>, basic_json_t, primitive_iterator_t>::value and
not std::is_same<uncvref_t<T>, basic_json_t>::value and
not std::is_same<uncvref_t<T>, typename basic_json_t::array_t::iterator>::value and
not std::is_same<uncvref_t<T>, typename basic_json_t::object_t::iterator>::value and
detail::conjunction<detail::negation<detail::is_compatible_basic_json_type<
@ -3211,23 +3238,34 @@ class basic_json
return get_impl(static_cast<ValueType *>(nullptr));
}
// if T is basic_json, simply returns *this
template <typename T,
enable_if_t<std::is_same<T, basic_json_t>::value, int> = 0>
basic_json get() const
{
return *this;
}
template <
typename T,
enable_if_t<detail::conjunction<detail::negation<detail::is_compatible_basic_json_type<
uncvref_t<T>, basic_json_t>>,
detail::has_from_json<JSONSerializer, basic_json_t,
uncvref_t<T>>>::value,
int> = 0 >
auto get() const -> uncvref_t<T>
enable_if_t<detail::conjunction<
detail::negation<detail::is_compatible_basic_json_type<
uncvref_t<T>, basic_json_t>>,
detail::has_from_json<JSONSerializer, basic_json_t,
uncvref_t<T>>>::value and
not std::is_same<basic_json_t, uncvref_t<T>>::value,
int> = 0>
// do we really want the uncvref ? if a user call get<int &>, shouldn't we static assert ?
auto get() const -> uncvref_t<T>
{
using type = uncvref_t<T>;
static_assert(std::is_default_constructible<type>::value&&
std::is_copy_constructible<type>::value,
"user-defined types must be DefaultConstructible and "
"CopyConstructible when used with get");
type ret;
JSONSerializer<type>::from_json(*this, ret);
return ret;
using type = uncvref_t<T>;
static_assert(std::is_default_constructible<type>::value &&
std::is_copy_constructible<type>::value,
"user-defined types must be DefaultConstructible and "
"CopyConstructible when used with get");
type ret;
JSONSerializer<type>::from_json(*this, ret);
return ret;
}
// This overload is chosen for non-default constructible user-defined-types

196
src/json.hpp.re2c
View File

@ -39,6 +39,7 @@ SOFTWARE.
#include <cstdint> // int64_t, uint64_t
#include <cstdlib> // strtod, strtof, strtold, strtoul
#include <cstring> // strlen
#include <forward_list> // forward_list
#include <functional> // function, hash, less
#include <initializer_list> // initializer_list
#include <iomanip> // setw
@ -272,6 +273,32 @@ struct external_constructor<value_t::number_integer>
}
};
template <>
struct external_constructor<value_t::array>
{
template <typename Json>
static void construct(Json &j, const typename Json::array_t& arr)
{
j.m_type = value_t::array;
j.m_value = arr;
j.assert_invariant();
}
template <typename Json, typename CompatibleArrayType,
enable_if_t<not std::is_same<CompatibleArrayType,
typename Json::array_t>::value,
int> = 0>
static void construct(Json &j, const CompatibleArrayType &arr)
{
using std::begin;
using std::end;
j.m_type = value_t::array;
j.m_value.array =
j.template create<typename Json::array_t>(begin(arr), end(arr));
j.assert_invariant();
}
};
// very useful construct against boilerplate (more boilerplate needed than in
// C++17: http://en.cppreference.com/w/cpp/types/void_t)
template <typename...> struct make_void
@ -432,8 +459,6 @@ template <typename T, typename BasicJson>
struct is_compatible_basic_json_type
{
static auto constexpr value =
std::is_same<T, BasicJson>::value or
is_compatible_array_type<BasicJson, T>::value or
is_compatible_object_type<typename BasicJson::object_t, T>::value;
};
@ -575,6 +600,17 @@ void to_json(Json &j, UnscopedEnumType e)
external_constructor<value_t::number_integer>::construct(j, e);
}
template <
typename Json, typename CompatibleArrayType,
enable_if_t<
is_compatible_array_type<Json, CompatibleArrayType>::value or
std::is_same<typename Json::array_t, CompatibleArrayType>::value,
int> = 0>
void to_json(Json &j, CompatibleArrayType const &arr)
{
external_constructor<value_t::array>::construct(j, arr);
}
template <typename Json>
void from_json(Json const& j, typename Json::boolean_t& b)
{
@ -618,6 +654,59 @@ void from_json(Json const &j, UnscopedEnumType& e)
e = static_cast<UnscopedEnumType>(val);
}
template <typename Json>
void from_json(Json const &j, typename Json::array_t &arr)
{
if (!j.is_array())
throw std::domain_error("type must be array, but is " + type_name(j));
arr = *const_cast<Json&>(j).template get_ptr<typename Json::array_t*>();
}
// forward_list doesn't have an insert method, TODO find a way to avoid including forward_list
template <typename Json, typename T, typename Allocator>
void from_json(Json const&j, std::forward_list<T, Allocator>& l)
{
// do not perform the check when user wants to retrieve jsons
// (except when it's null.. ?)
if (j.is_null())
throw std::domain_error("type must be array, but is " + type_name(j));
if (not std::is_same<T, Json>::value)
{
if (!j.is_array())
throw std::domain_error("type must be array, but is " + type_name(j));
}
for (auto it = j.rbegin(), end = j.rend(); it != end; ++it)
l.push_front(it->template get<T>());
}
template <
typename Json, typename CompatibleArrayType,
enable_if_t<is_compatible_array_type<Json, CompatibleArrayType>::value and
not std::is_same<typename Json::array_t,
CompatibleArrayType>::value,
int> = 0>
void from_json(Json const &j, CompatibleArrayType &arr)
{
if (j.is_null())
throw std::domain_error("type must be array, but is " + type_name(j));
// when T == Json, do not check if value_t is correct
if (not std::is_same<typename CompatibleArrayType::value_type, Json>::value)
{
if (!j.is_array())
throw std::domain_error("type must be array, but is " + type_name(j));
}
using std::begin;
using std::end;
std::transform(
j.begin(), j.end(), std::inserter(arr, end(arr)), [](Json const &i)
{
// get<Json>() returns *this, this won't call a from_json method when
// value_type is Json
return i.template get<typename CompatibleArrayType::value_type>();
});
}
// overload for arithmetic types, not chosen for basic_json template arguments (BooleanType, etc..)
//
// note: Is it really necessary to provide explicit overloads for boolean_t etc..
@ -1781,69 +1870,6 @@ class basic_json
assert_invariant();
}
/*!
@brief create an array (explicit)
Create an array JSON value with a given content.
@param[in] val a value for the array
@complexity Linear in the size of the passed @a val.
@throw std::bad_alloc if allocation for array value fails
@liveexample{The following code shows the constructor with an @ref array_t
parameter.,basic_json__array_t}
@sa @ref basic_json(const CompatibleArrayType&) -- create an array value
from a compatible STL containers
@since version 1.0.0
*/
basic_json(const array_t& val)
: m_type(value_t::array), m_value(val)
{
assert_invariant();
}
/*!
@brief create an array (implicit)
Create an array JSON value with a given content. This constructor allows
any type @a CompatibleArrayType that can be used to construct values of
type @ref array_t.
@tparam CompatibleArrayType An object type whose `value_type` is
compatible to @ref array_t. Examples include `std::vector`, `std::deque`,
`std::list`, `std::forward_list`, `std::array`, `std::set`,
`std::unordered_set`, `std::multiset`, and `unordered_multiset` with a
`value_type` from which a @ref basic_json value can be constructed.
@param[in] val a value for the array
@complexity Linear in the size of the passed @a val.
@throw std::bad_alloc if allocation for array value fails
@liveexample{The following code shows the constructor with several
compatible array type parameters.,basic_json__CompatibleArrayType}
@sa @ref basic_json(const array_t&) -- create an array value
@since version 1.0.0
*/
template <class CompatibleArrayType,
enable_if_t<detail::is_compatible_array_type<basic_json_t, CompatibleArrayType>::value,
int> = 0>
basic_json(const CompatibleArrayType& val) : m_type(value_t::array)
{
using std::begin;
using std::end;
m_value.array = create<array_t>(begin(val), end(val));
assert_invariant();
}
// constructor chosen when:
// - JSONSerializer::to_json exists for type T
// - T is not a istream, nor convertible to basic_json (float, vectors, etc)
@ -1852,6 +1878,7 @@ class basic_json
typename T,
enable_if_t<not std::is_base_of<std::istream, uncvref_t<T>>::value and
not detail::is_basic_json_nested_class<uncvref_t<T>, basic_json_t, primitive_iterator_t>::value and
not std::is_same<uncvref_t<T>, basic_json_t>::value and
not std::is_same<uncvref_t<T>, typename basic_json_t::array_t::iterator>::value and
not std::is_same<uncvref_t<T>, typename basic_json_t::object_t::iterator>::value and
detail::conjunction<detail::negation<detail::is_compatible_basic_json_type<
@ -3209,23 +3236,34 @@ class basic_json
return get_impl(static_cast<ValueType *>(nullptr));
}
// if T is basic_json, simply returns *this
template <typename T,
enable_if_t<std::is_same<T, basic_json_t>::value, int> = 0>
basic_json get() const
{
return *this;
}
template <
typename T,
enable_if_t<detail::conjunction<detail::negation<detail::is_compatible_basic_json_type<
uncvref_t<T>, basic_json_t>>,
detail::has_from_json<JSONSerializer, basic_json_t,
uncvref_t<T>>>::value,
int> = 0 >
auto get() const -> uncvref_t<T>
enable_if_t<detail::conjunction<
detail::negation<detail::is_compatible_basic_json_type<
uncvref_t<T>, basic_json_t>>,
detail::has_from_json<JSONSerializer, basic_json_t,
uncvref_t<T>>>::value and
not std::is_same<basic_json_t, uncvref_t<T>>::value,
int> = 0>
// do we really want the uncvref ? if a user call get<int &>, shouldn't we static assert ?
auto get() const -> uncvref_t<T>
{
using type = uncvref_t<T>;
static_assert(std::is_default_constructible<type>::value&&
std::is_copy_constructible<type>::value,
"user-defined types must be DefaultConstructible and "
"CopyConstructible when used with get");
type ret;
JSONSerializer<type>::from_json(*this, ret);
return ret;
using type = uncvref_t<T>;
static_assert(std::is_default_constructible<type>::value &&
std::is_copy_constructible<type>::value,
"user-defined types must be DefaultConstructible and "
"CopyConstructible when used with get");
type ret;
JSONSerializer<type>::from_json(*this, ret);
return ret;
}
// This overload is chosen for non-default constructible user-defined-types

2
test/src/unit-conversions.cpp
View File

@ -1004,6 +1004,8 @@ TEST_CASE("value conversion")
CHECK_THROWS_AS((json().get<std::vector<json>>()), std::logic_error);
CHECK_THROWS_AS((json().get<std::list<json>>()), std::logic_error);
// does type really must be an array? or it rather must not be null?
// that's what I thought when other test like this one broke
CHECK_THROWS_WITH((json().get<std::list<int>>()), "type must be array, but is null");
CHECK_THROWS_WITH((json().get<std::vector<int>>()), "type must be array, but is null");
CHECK_THROWS_WITH((json().get<std::vector<json>>()), "type must be array, but is null");

26
test/src/unit-udt.cpp
View File

@ -391,19 +391,19 @@ TEST_CASE("adl_serializer specialization", "[udt]")
namespace nlohmann
{
// this might work in the future, not in the scope of this PR though
// we have to make this very clear in the doc
template <typename T>
struct adl_serializer<std::vector<T>>
{
static void to_json(json& j, std::vector<T> const& opt)
{
}
static void from_json(json const& j, std::vector<T>& opt)
{
}
};
// TODO provide a real example, since this works now :)
// template <typename T>
// struct adl_serializer<std::vector<T>>
// {
// static void to_json(json& j, std::vector<T> const& opt)
// {
//
// }
//
// static void from_json(json const& j, std::vector<T>& opt)
// {
// }
// };
}
TEST_CASE("current supported types are preferred over specializations", "[udt]")