support construction from other basic_json types
Before this patch, `basic_json` types with different template arguments were treated as `CompatibleArrayType`. Which sometimes leads to recursive calls and stack overflows. This patch adds a constructor and a `get` overload to deal with different `basic_json` types.
This commit is contained in:
Théo DELRIEU
parent
c22f2d41f3
commit
8711ec6034
5 changed files with 281 additions and 8 deletions
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@ -233,7 +233,7 @@ struct is_compatible_complete_type
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{
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static constexpr bool value =
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not std::is_base_of<std::istream, CompatibleCompleteType>::value and
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not std::is_same<BasicJsonType, CompatibleCompleteType>::value and
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not is_basic_json<CompatibleCompleteType>::value and
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not is_basic_json_nested_type<BasicJsonType, CompatibleCompleteType>::value and
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has_to_json<BasicJsonType, CompatibleCompleteType>::value;
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};
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@ -1207,6 +1207,7 @@ class basic_json
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- @a CompatibleType is not derived from `std::istream`,
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- @a CompatibleType is not @ref basic_json (to avoid hijacking copy/move
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constructors),
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- @a CompatibleType is not a different @ref basic_json type (i.e. with different template arguments)
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- @a CompatibleType is not a @ref basic_json nested type (e.g.,
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@ref json_pointer, @ref iterator, etc ...)
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- @ref @ref json_serializer<U> has a
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@ -1242,6 +1243,77 @@ class basic_json
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assert_invariant();
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}
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/*!
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@brief create a JSON value from an existing one
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This is a constructor for existing @ref basic_json types.
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It does not hijack copy/move constructors, since the parameter has different template arguments than the current ones.
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The constructor tries to convert the internal @ref m_value of the parameter.
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@tparam BasicJsonType a type such that:
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- @a BasicJsonType is a @ref basic_json type.
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- @a BasicJsonType has different template arguments than @ref basic_json_t.
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@param[in] val the @ref basic_json value to be converted.
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@complexity Usually linear in the size of the passed @a val, also
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depending on the implementation of the called `to_json()`
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method.
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@exceptionsafety Depends on the called constructor. For types directly
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supported by the library (i.e., all types for which no `to_json()` function
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was provided), strong guarantee holds: if an exception is thrown, there are
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no changes to any JSON value.
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@since version 3.1.2
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*/
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template <typename BasicJsonType,
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detail::enable_if_t<
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detail::is_basic_json<BasicJsonType>::value and not std::is_same<basic_json, BasicJsonType>::value, int> = 0>
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basic_json(const BasicJsonType& val)
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{
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using other_boolean_t = typename BasicJsonType::boolean_t;
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using other_number_float_t = typename BasicJsonType::number_float_t;
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using other_number_integer_t = typename BasicJsonType::number_integer_t;
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using other_number_unsigned_t = typename BasicJsonType::number_unsigned_t;
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using other_string_t = typename BasicJsonType::string_t;
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using other_object_t = typename BasicJsonType::object_t;
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using other_array_t = typename BasicJsonType::array_t;
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switch (val.type())
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{
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case value_t::boolean:
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JSONSerializer<other_boolean_t>::to_json(*this, val.template get<other_boolean_t>());
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break;
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case value_t::number_float:
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JSONSerializer<other_number_float_t>::to_json(*this, val.template get<other_number_float_t>());
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break;
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case value_t::number_integer:
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JSONSerializer<other_number_integer_t>::to_json(*this, val.template get<other_number_integer_t>());
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break;
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case value_t::number_unsigned:
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JSONSerializer<other_number_unsigned_t>::to_json(*this, val.template get<other_number_unsigned_t>());
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break;
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case value_t::string:
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JSONSerializer<other_string_t>::to_json(*this, val.template get_ref<const other_string_t&>());
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break;
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case value_t::object:
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JSONSerializer<other_object_t>::to_json(*this, val.template get_ref<const other_object_t&>());
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break;
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case value_t::array:
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JSONSerializer<other_array_t>::to_json(*this, val.template get_ref<const other_array_t&>());
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break;
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case value_t::null:
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*this = nullptr;
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break;
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case value_t::discarded:
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m_type = value_t::discarded;
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break;
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}
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assert_invariant();
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}
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/*!
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@brief create a container (array or object) from an initializer list
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@ -2414,6 +2486,31 @@ class basic_json
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return *this;
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}
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/*!
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@brief get special-case overload
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This overloads converts the current @ref basic_json in a different @ref basic_json type
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@tparam BasicJsonType == @ref basic_json
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@return a copy of *this, converted into @tparam BasicJsonType
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@complexity Depending on the implementation of the called `from_json()`
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method.
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@since version 3.1.2
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*/
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template<typename BasicJsonType, detail::enable_if_t<
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not std::is_same<BasicJsonType, basic_json>::value and
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detail::is_basic_json<BasicJsonType>::value
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,
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int> = 0>
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BasicJsonType get() const
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{
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return *this;
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}
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/*!
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@brief get a value (explicit)
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@ -2455,7 +2552,7 @@ class basic_json
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*/
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template<typename ValueTypeCV, typename ValueType = detail::uncvref_t<ValueTypeCV>,
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detail::enable_if_t <
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not std::is_same<basic_json_t, ValueType>::value and
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not detail::is_basic_json<ValueType>::value and
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detail::has_from_json<basic_json_t, ValueType>::value and
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not detail::has_non_default_from_json<basic_json_t, ValueType>::value,
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int> = 0>
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@ -2721,7 +2818,8 @@ class basic_json
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template < typename ValueType, typename std::enable_if <
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not std::is_pointer<ValueType>::value and
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not std::is_same<ValueType, detail::json_ref<basic_json>>::value and
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not std::is_same<ValueType, typename string_t::value_type>::value
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not std::is_same<ValueType, typename string_t::value_type>::value and
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not detail::is_basic_json<ValueType>::value
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#ifndef _MSC_VER // fix for issue #167 operator<< ambiguity under VS2015
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and not std::is_same<ValueType, std::initializer_list<typename string_t::value_type>>::value
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#endif
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@ -466,7 +466,7 @@ struct is_compatible_complete_type
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{
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static constexpr bool value =
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not std::is_base_of<std::istream, CompatibleCompleteType>::value and
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not std::is_same<BasicJsonType, CompatibleCompleteType>::value and
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not is_basic_json<CompatibleCompleteType>::value and
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not is_basic_json_nested_type<BasicJsonType, CompatibleCompleteType>::value and
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has_to_json<BasicJsonType, CompatibleCompleteType>::value;
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};
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@ -10805,6 +10805,7 @@ class basic_json
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- @a CompatibleType is not derived from `std::istream`,
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- @a CompatibleType is not @ref basic_json (to avoid hijacking copy/move
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constructors),
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- @a CompatibleType is not a different @ref basic_json type (i.e. with different template arguments)
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- @a CompatibleType is not a @ref basic_json nested type (e.g.,
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@ref json_pointer, @ref iterator, etc ...)
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- @ref @ref json_serializer<U> has a
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@ -10840,6 +10841,77 @@ class basic_json
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assert_invariant();
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}
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/*!
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@brief create a JSON value from an existing one
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This is a constructor for existing @ref basic_json types.
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It does not hijack copy/move constructors, since the parameter has different template arguments than the current ones.
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The constructor tries to convert the internal @ref m_value of the parameter.
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@tparam BasicJsonType a type such that:
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- @a BasicJsonType is a @ref basic_json type.
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- @a BasicJsonType has different template arguments than @ref basic_json_t.
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@param[in] val the @ref basic_json value to be converted.
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@complexity Usually linear in the size of the passed @a val, also
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depending on the implementation of the called `to_json()`
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method.
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@exceptionsafety Depends on the called constructor. For types directly
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supported by the library (i.e., all types for which no `to_json()` function
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was provided), strong guarantee holds: if an exception is thrown, there are
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no changes to any JSON value.
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@since version 3.1.2
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*/
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template <typename BasicJsonType,
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detail::enable_if_t<
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detail::is_basic_json<BasicJsonType>::value and not std::is_same<basic_json, BasicJsonType>::value, int> = 0>
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basic_json(const BasicJsonType& val)
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{
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using other_boolean_t = typename BasicJsonType::boolean_t;
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using other_number_float_t = typename BasicJsonType::number_float_t;
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using other_number_integer_t = typename BasicJsonType::number_integer_t;
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using other_number_unsigned_t = typename BasicJsonType::number_unsigned_t;
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using other_string_t = typename BasicJsonType::string_t;
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using other_object_t = typename BasicJsonType::object_t;
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using other_array_t = typename BasicJsonType::array_t;
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switch (val.type())
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{
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case value_t::boolean:
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JSONSerializer<other_boolean_t>::to_json(*this, val.template get<other_boolean_t>());
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break;
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case value_t::number_float:
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JSONSerializer<other_number_float_t>::to_json(*this, val.template get<other_number_float_t>());
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break;
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case value_t::number_integer:
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JSONSerializer<other_number_integer_t>::to_json(*this, val.template get<other_number_integer_t>());
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break;
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case value_t::number_unsigned:
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JSONSerializer<other_number_unsigned_t>::to_json(*this, val.template get<other_number_unsigned_t>());
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break;
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case value_t::string:
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JSONSerializer<other_string_t>::to_json(*this, val.template get_ref<const other_string_t&>());
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break;
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case value_t::object:
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JSONSerializer<other_object_t>::to_json(*this, val.template get_ref<const other_object_t&>());
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break;
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case value_t::array:
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JSONSerializer<other_array_t>::to_json(*this, val.template get_ref<const other_array_t&>());
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break;
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case value_t::null:
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*this = nullptr;
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break;
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case value_t::discarded:
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m_type = value_t::discarded;
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break;
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}
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assert_invariant();
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}
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/*!
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@brief create a container (array or object) from an initializer list
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@ -12012,6 +12084,31 @@ class basic_json
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return *this;
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}
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/*!
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@brief get special-case overload
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This overloads converts the current @ref basic_json in a different @ref basic_json type
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@tparam BasicJsonType == @ref basic_json
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@return a copy of *this, converted into @tparam BasicJsonType
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@complexity Depending on the implementation of the called `from_json()`
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method.
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@since version 3.1.2
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*/
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template<typename BasicJsonType, detail::enable_if_t<
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not std::is_same<BasicJsonType, basic_json>::value and
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detail::is_basic_json<BasicJsonType>::value
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,
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int> = 0>
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BasicJsonType get() const
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{
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return *this;
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}
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/*!
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@brief get a value (explicit)
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@ -12053,7 +12150,7 @@ class basic_json
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*/
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template<typename ValueTypeCV, typename ValueType = detail::uncvref_t<ValueTypeCV>,
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detail::enable_if_t <
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not std::is_same<basic_json_t, ValueType>::value and
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not detail::is_basic_json<ValueType>::value and
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detail::has_from_json<basic_json_t, ValueType>::value and
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not detail::has_non_default_from_json<basic_json_t, ValueType>::value,
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int> = 0>
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@ -12319,7 +12416,8 @@ class basic_json
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template < typename ValueType, typename std::enable_if <
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not std::is_pointer<ValueType>::value and
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not std::is_same<ValueType, detail::json_ref<basic_json>>::value and
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not std::is_same<ValueType, typename string_t::value_type>::value
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not std::is_same<ValueType, typename string_t::value_type>::value and
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not detail::is_basic_json<ValueType>::value
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#ifndef _MSC_VER // fix for issue #167 operator<< ambiguity under VS2015
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and not std::is_same<ValueType, std::initializer_list<typename string_t::value_type>>::value
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#endif
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@ -316,8 +316,8 @@ TEST_CASE("object inspection")
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SECTION("round trips")
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{
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for (const auto& s :
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{"3.141592653589793", "1000000000000000010E5"
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})
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{"3.141592653589793", "1000000000000000010E5"
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})
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{
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json j1 = json::parse(s);
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std::string s1 = j1.dump();
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@ -693,6 +693,83 @@ TEST_CASE("custom serializer that does adl by default", "[udt]")
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CHECK(me == cj.get<udt::person>());
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}
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TEST_CASE("different basic_json types conversions")
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{
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using json = nlohmann::json;
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SECTION("null")
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{
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json j;
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custom_json cj = j;
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CHECK(cj == nullptr);
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}
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SECTION("boolean")
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{
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json j = true;
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custom_json cj = j;
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CHECK(cj == true);
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}
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SECTION("discarded")
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{
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json j(json::value_t::discarded);
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custom_json cj;
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CHECK_NOTHROW(cj = j);
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CHECK(cj.type() == custom_json::value_t::discarded);
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}
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SECTION("array")
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{
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json j = {1, 2, 3};
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custom_json cj = j;
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CHECK((cj == std::vector<int> {1, 2, 3}));
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}
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SECTION("integer")
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{
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json j = 42;
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custom_json cj = j;
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CHECK(cj == 42);
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}
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SECTION("float")
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{
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json j = 42.0;
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custom_json cj = j;
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CHECK(cj == 42.0);
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}
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SECTION("unsigned")
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{
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json j = 42u;
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custom_json cj = j;
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CHECK(cj == 42u);
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}
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SECTION("string")
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{
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json j = "forty-two";
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custom_json cj = j;
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CHECK(cj == "forty-two");
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}
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SECTION("object")
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{
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json j = {{"forty", "two"}};
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custom_json cj = j;
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auto m = j.get<std::map<std::string, std::string>>();
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CHECK(cj == m);
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}
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SECTION("get<custom_json>")
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{
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json j = 42;
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custom_json cj = j.get<custom_json>();
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CHECK(cj == 42);
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}
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}
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namespace
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{
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struct incomplete;
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|
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