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add a switch to enable implicit conversions (defaults to true)

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wrap implicit conversions tests around the JSON_USE_IMPLICIT_CONVERSIONS
macro
This commit is contained in:
Théo DELRIEU 2020-07-16 11:11:35 +02:00
parent 2cd10a7405
commit 74b446f5fd
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GPG key ID: 7D6E00D1DF01DEAF
15 changed files with 151 additions and 64 deletions
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10
include/nlohmann/detail/conversions/from_json.hpp
View file

@ -128,7 +128,7 @@ void from_json(const BasicJsonType& j, EnumType& e)
// forward_list doesn't have an insert method
template<typename BasicJsonType, typename T, typename Allocator,
enable_if_t<std::is_convertible<BasicJsonType, T>::value, int> = 0>
enable_if_t<is_getable<BasicJsonType, T>::value, int> = 0>
void from_json(const BasicJsonType& j, std::forward_list<T, Allocator>& l)
{
if (JSON_HEDLEY_UNLIKELY(!j.is_array()))
@ -145,7 +145,7 @@ void from_json(const BasicJsonType& j, std::forward_list<T, Allocator>& l)
// valarray doesn't have an insert method
template<typename BasicJsonType, typename T,
enable_if_t<std::is_convertible<BasicJsonType, T>::value, int> = 0>
enable_if_t<is_getable<BasicJsonType, T>::value, int> = 0>
void from_json(const BasicJsonType& j, std::valarray<T>& l)
{
if (JSON_HEDLEY_UNLIKELY(!j.is_array()))
@ -153,7 +153,11 @@ void from_json(const BasicJsonType& j, std::valarray<T>& l)
JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(j.type_name())));
}
l.resize(j.size());
std::copy(j.begin(), j.end(), std::begin(l));
std::transform(j.begin(), j.end(), std::begin(l),
[](const BasicJsonType & elem)
{
return elem.template get<T>();
});
}
template<typename BasicJsonType, typename T, std::size_t N>

10
include/nlohmann/detail/macro_scope.hpp
View file

@ -284,3 +284,13 @@
#define NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(Type, ...) \
void to_json(nlohmann::json& j, const Type& t) { NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_TO, __VA_ARGS__)) } \
void from_json(const nlohmann::json& j, Type& t) { NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_PASTE(NLOHMANN_JSON_FROM, __VA_ARGS__)) }
#ifndef JSON_USE_IMPLICIT_CONVERSIONS
#define JSON_USE_IMPLICIT_CONVERSIONS 1
#endif
#if JSON_USE_IMPLICIT_CONVERSIONS
#define JSON_EXPLICIT
#else
#define JSON_EXPLICIT explicit
#endif

1
include/nlohmann/detail/macro_unscope.hpp
View file

@ -18,5 +18,6 @@
#undef JSON_HAS_CPP_17
#undef NLOHMANN_BASIC_JSON_TPL_DECLARATION
#undef NLOHMANN_BASIC_JSON_TPL
#undef JSON_EXPLICIT
#include <nlohmann/thirdparty/hedley/hedley_undef.hpp>

10
include/nlohmann/detail/meta/type_traits.hpp
View file

@ -94,6 +94,16 @@ using get_template_function = decltype(std::declval<T>().template get<U>());
template<typename BasicJsonType, typename T, typename = void>
struct has_from_json : std::false_type {};
// trait checking if j.get<T> is valid
// use this trait instead of std::is_constructible or std::is_convertible,
// both rely on, or make use of implicit conversions, and thus fail when T
// has several constructors/operator= (see https://github.com/nlohmann/json/issues/958)
template <typename BasicJsonType, typename T>
struct is_getable
{
static constexpr bool value = is_detected<get_template_function, const BasicJsonType&, T>::value;
};
template<typename BasicJsonType, typename T>
struct has_from_json < BasicJsonType, T,
enable_if_t < !is_basic_json<T>::value >>

19
include/nlohmann/json.hpp
View file

@ -3229,7 +3229,7 @@ class basic_json
#endif
&& detail::is_detected<detail::get_template_function, const basic_json_t&, ValueType>::value
, int >::type = 0 >
operator ValueType() const
JSON_EXPLICIT operator ValueType() const
{
// delegate the call to get<>() const
return get<ValueType>();
@ -3784,8 +3784,9 @@ class basic_json
@since version 1.0.0
*/
// using std::is_convertible in a std::enable_if will fail when using explicit conversions
template < class ValueType, typename std::enable_if <
std::is_convertible<basic_json_t, ValueType>::value
detail::is_getable<basic_json_t, ValueType>::value
&& !std::is_same<value_t, ValueType>::value, int >::type = 0 >
ValueType value(const typename object_t::key_type& key, const ValueType& default_value) const
{
@ -3796,7 +3797,7 @@ class basic_json
const auto it = find(key);
if (it != end())
{
return *it;
return it->template get<ValueType>();
}
return default_value;
@ -3858,7 +3859,7 @@ class basic_json
@since version 2.0.2
*/
template<class ValueType, typename std::enable_if<
std::is_convertible<basic_json_t, ValueType>::value, int>::type = 0>
detail::is_getable<basic_json_t, ValueType>::value, int>::type = 0>
ValueType value(const json_pointer& ptr, const ValueType& default_value) const
{
// at only works for objects
@ -3867,7 +3868,7 @@ class basic_json
// if pointer resolves a value, return it or use default value
JSON_TRY
{
return ptr.get_checked(this);
return ptr.get_checked(this).template get<ValueType>();
}
JSON_INTERNAL_CATCH (out_of_range&)
{
@ -8341,8 +8342,8 @@ class basic_json
}
// collect mandatory members
const std::string op = get_value("op", "op", true);
const std::string path = get_value(op, "path", true);
const auto op = get_value("op", "op", true).template get<std::string>();
const auto path = get_value(op, "path", true).template get<std::string>();
json_pointer ptr(path);
switch (get_op(op))
@ -8368,7 +8369,7 @@ class basic_json
case patch_operations::move:
{
const std::string from_path = get_value("move", "from", true);
const auto from_path = get_value("move", "from", true).template get<std::string>();
json_pointer from_ptr(from_path);
// the "from" location must exist - use at()
@ -8385,7 +8386,7 @@ class basic_json
case patch_operations::copy:
{
const std::string from_path = get_value("copy", "from", true);
const auto from_path = get_value("copy", "from", true).template get<std::string>();
const json_pointer from_ptr(from_path);
// the "from" location must exist - use at()