mirror of https://github.com/nlohmann/json.git
📝 added more documentation
Niels Lohmann
parent
4d3053cd42
commit
77bb7af5d9
132
src/json.hpp
132
src/json.hpp
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@ -956,6 +956,8 @@ default; will be used in @ref number_integer_t)
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default; will be used in @ref number_float_t)
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@tparam AllocatorType type of the allocator to use (`std::allocator` by
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default)
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@tparam JSONSerializer the serializer to resolve internal calls to `to_json()`
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and `from_json()`
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@requirement The class satisfies the following concept requirements:
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- Basic
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@ -2997,6 +2999,10 @@ class basic_json
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/// @}
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private:
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//////////////////
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// value access //
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//////////////////
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/// get a boolean (explicit)
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boolean_t get_impl(boolean_t* /*unused*/) const
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{
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@ -3124,12 +3130,17 @@ class basic_json
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}
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public:
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/// @name value access
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/// Direct access to the stored value of a JSON value.
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/// @{
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/*!
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@brief get special-case overload
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This overloads avoids a lot of template boilerplate, it can be seen as the identity method
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This overloads avoids a lot of template boilerplate, it can be seen as the
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identity method
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@tparam T type; T == @ref basic_json
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@tparam BasicJsonType == @ref basic_json
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@return a copy of *this
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@ -3138,8 +3149,8 @@ class basic_json
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@since version 2.1.0
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*/
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template <
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typename T,
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detail::enable_if_t<std::is_same<typename std::remove_const<T>::type,
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typename BasicJsonType,
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detail::enable_if_t<std::is_same<typename std::remove_const<BasicJsonType>::type,
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basic_json_t>::value,
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int> = 0 >
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basic_json get() const
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@ -3148,66 +3159,111 @@ class basic_json
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}
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/*!
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@brief get overload for CopyConstructible and DefaultConstructible types
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construct a default U value, and call @ref json_serializer<U> from_json method with it
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@brief get a value (explicit)
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Explicit type conversion between the JSON value and a compatible value
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which is [CopyConstructible](http://en.cppreference.com/w/cpp/concept/CopyConstructible)
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and [DefaultConstructible](http://en.cppreference.com/w/cpp/concept/DefaultConstructible).
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The value is converted by calling the @ref json_serializer<ValueType>
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`from_json()` method.
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The function is equivalent to executing
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@code {.cpp}
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ValueType ret;
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JSONSerializer<ValueType>::from_json(*this, ret);
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return ret;
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@endcode
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This overloads is chosen if:
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- U is not @ref basic_json
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- @ref json_serializer<U> has a from_json method of the form: void from_json(const @ref basic_json&, U&)
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- @ref json_serializer<U> does not have a from_json method of the form: U from_json(const @ref basic_json&);
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- @a ValueType is not @ref basic_json,
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- @ref json_serializer<ValueType> has a `from_json()` method of the form
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`void from_json(const @ref basic_json&, ValueType&)`, and
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- @ref json_serializer<ValueType> does not have a `from_json()` method of
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the form `ValueType from_json(const @ref basic_json&)`
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@return a value of type U
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@tparam ValueTypeCV the provided value type
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@tparam ValueType the returned value type
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@throw what json_serializer<U> from_json method throws
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@return copy of the JSON value, converted to @a ValueType
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@throw what @ref json_serializer<ValueType> `from_json()` method throws
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@liveexample{The example below shows several conversions from JSON values
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to other types. There a few things to note: (1) Floating-point numbers can
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be converted to integers\, (2) A JSON array can be converted to a standard
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`std::vector<short>`\, (3) A JSON object can be converted to C++
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associative containers such as `std::unordered_map<std::string\,
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json>`.,get__ValueType_const}
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@since version 2.1.0
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*/
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template <
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typename T,
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typename U = detail::uncvref_t<T>,
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typename ValueTypeCV,
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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, U>::value and
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detail::has_from_json<basic_json_t, U>::value and
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not detail::has_non_default_from_json<basic_json_t, U>::value,
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not std::is_same<basic_json_t, 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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U get() const noexcept(noexcept(JSONSerializer<U>::from_json(
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std::declval<const basic_json_t&>(), std::declval<U&>())))
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ValueType get() const noexcept(noexcept(
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JSONSerializer<ValueType>::from_json(std::declval<const basic_json_t&>(), std::declval<ValueType&>())))
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{
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// we cannot static_assert on T being non-const, because there is support
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// for get<const basic_json_t>(), which is why we still need the uncvref
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static_assert(not std::is_reference<T>::value, "get cannot be used with reference types, you might want to use get_ref");
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static_assert(std::is_default_constructible<U>::value,
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"Types must be DefaultConstructible when used with get");
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U ret;
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JSONSerializer<U>::from_json(*this, ret);
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// we cannot static_assert on ValueTypeCV being non-const, because
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// there is support for get<const basic_json_t>(), which is why we
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// still need the uncvref
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static_assert(not std::is_reference<ValueTypeCV>::value,
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"get() cannot be used with reference types, you might want to use get_ref()");
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static_assert(std::is_default_constructible<ValueType>::value,
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"types must be DefaultConstructible when used with get()");
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ValueType ret;
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JSONSerializer<ValueType>::from_json(*this, ret);
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return ret;
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}
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/*!
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@brief get overload for types than cannot be default constructed or copy constructed
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@brief get a value (explicit); special case
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If @ref json_serializer<U> has both overloads of from_json, this one is chosen
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Explicit type conversion between the JSON value and a compatible value
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which is **not** [CopyConstructible](http://en.cppreference.com/w/cpp/concept/CopyConstructible)
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and **not** [DefaultConstructible](http://en.cppreference.com/w/cpp/concept/DefaultConstructible).
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The value is converted by calling the @ref json_serializer<ValueType>
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`from_json()` method.
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The function is equivalent to executing
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@code {.cpp}
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return JSONSerializer<ValueTypeCV>::from_json(*this);
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@endcode
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This overloads is chosen if:
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- U is not @ref basic_json
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- @ref json_serializer<U> has a from_json method of the form: U from_json(const @ref basic_json&);
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- @a ValueType is not @ref basic_json and
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- @ref json_serializer<ValueType> has a `from_json()` method of the form
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`ValueType from_json(const @ref basic_json&)`
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@return a value of type U
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@note If @ref json_serializer<ValueType> has both overloads of
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`from_json()`, this one is chosen.
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@throw what json_serializer<U> from_json method throws
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@tparam ValueTypeCV the provided value type
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@tparam ValueType the returned value type
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@return copy of the JSON value, converted to @a ValueType
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@throw what @ref json_serializer<ValueType> `from_json()` method throws
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@since version 2.1.0
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*/
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template <
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typename T,
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typename U = detail::uncvref_t<T>,
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detail::enable_if_t<not std::is_same<basic_json_t, U>::value and
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typename ValueTypeCV,
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typename ValueType = detail::uncvref_t<ValueTypeCV>,
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detail::enable_if_t<not std::is_same<basic_json_t, ValueType>::value and
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detail::has_non_default_from_json<basic_json_t,
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U>::value, int> = 0 >
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U get() const noexcept(noexcept(JSONSerializer<T>::from_json(std::declval<const basic_json_t&>())))
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ValueType>::value, int> = 0 >
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ValueType get() const noexcept(noexcept(
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JSONSerializer<ValueTypeCV>::from_json(std::declval<const basic_json_t&>())))
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{
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static_assert(not std::is_reference<T>::value, "get cannot be used with reference types, you might want to use get_ref");
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return JSONSerializer<T>::from_json(*this);
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static_assert(not std::is_reference<ValueTypeCV>::value,
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"get() cannot be used with reference types, you might want to use get_ref()");
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return JSONSerializer<ValueTypeCV>::from_json(*this);
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}
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/*!
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@ -956,6 +956,8 @@ default; will be used in @ref number_integer_t)
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default; will be used in @ref number_float_t)
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@tparam AllocatorType type of the allocator to use (`std::allocator` by
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default)
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@tparam JSONSerializer the serializer to resolve internal calls to `to_json()`
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and `from_json()`
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@requirement The class satisfies the following concept requirements:
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- Basic
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@ -2997,6 +2999,10 @@ class basic_json
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/// @}
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private:
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//////////////////
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// value access //
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//////////////////
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/// get a boolean (explicit)
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boolean_t get_impl(boolean_t* /*unused*/) const
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{
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@ -3124,12 +3130,17 @@ class basic_json
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}
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public:
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/// @name value access
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/// Direct access to the stored value of a JSON value.
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/// @{
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/*!
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@brief get special-case overload
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This overloads avoids a lot of template boilerplate, it can be seen as the identity method
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This overloads avoids a lot of template boilerplate, it can be seen as the
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identity method
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@tparam T type; T == @ref basic_json
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@tparam BasicJsonType == @ref basic_json
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@return a copy of *this
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@ -3138,8 +3149,8 @@ class basic_json
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@since version 2.1.0
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*/
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template <
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typename T,
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detail::enable_if_t<std::is_same<typename std::remove_const<T>::type,
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typename BasicJsonType,
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detail::enable_if_t<std::is_same<typename std::remove_const<BasicJsonType>::type,
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basic_json_t>::value,
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int> = 0 >
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basic_json get() const
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@ -3148,66 +3159,111 @@ class basic_json
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}
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/*!
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@brief get overload for CopyConstructible and DefaultConstructible types
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construct a default U value, and call @ref json_serializer<U> from_json method with it
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@brief get a value (explicit)
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Explicit type conversion between the JSON value and a compatible value
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which is [CopyConstructible](http://en.cppreference.com/w/cpp/concept/CopyConstructible)
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and [DefaultConstructible](http://en.cppreference.com/w/cpp/concept/DefaultConstructible).
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The value is converted by calling the @ref json_serializer<ValueType>
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`from_json()` method.
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The function is equivalent to executing
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@code {.cpp}
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ValueType ret;
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JSONSerializer<ValueType>::from_json(*this, ret);
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return ret;
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@endcode
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This overloads is chosen if:
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- U is not @ref basic_json
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- @ref json_serializer<U> has a from_json method of the form: void from_json(const @ref basic_json&, U&)
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- @ref json_serializer<U> does not have a from_json method of the form: U from_json(const @ref basic_json&);
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- @a ValueType is not @ref basic_json,
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- @ref json_serializer<ValueType> has a `from_json()` method of the form
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`void from_json(const @ref basic_json&, ValueType&)`, and
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- @ref json_serializer<ValueType> does not have a `from_json()` method of
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the form `ValueType from_json(const @ref basic_json&)`
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@return a value of type U
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@tparam ValueTypeCV the provided value type
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@tparam ValueType the returned value type
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@throw what json_serializer<U> from_json method throws
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@return copy of the JSON value, converted to @a ValueType
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@throw what @ref json_serializer<ValueType> `from_json()` method throws
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@liveexample{The example below shows several conversions from JSON values
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to other types. There a few things to note: (1) Floating-point numbers can
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be converted to integers\, (2) A JSON array can be converted to a standard
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`std::vector<short>`\, (3) A JSON object can be converted to C++
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associative containers such as `std::unordered_map<std::string\,
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json>`.,get__ValueType_const}
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@since version 2.1.0
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*/
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template <
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typename T,
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typename U = detail::uncvref_t<T>,
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typename ValueTypeCV,
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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, U>::value and
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detail::has_from_json<basic_json_t, U>::value and
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not detail::has_non_default_from_json<basic_json_t, U>::value,
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not std::is_same<basic_json_t, 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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U get() const noexcept(noexcept(JSONSerializer<U>::from_json(
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std::declval<const basic_json_t&>(), std::declval<U&>())))
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ValueType get() const noexcept(noexcept(
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JSONSerializer<ValueType>::from_json(std::declval<const basic_json_t&>(), std::declval<ValueType&>())))
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{
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// we cannot static_assert on T being non-const, because there is support
|
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// for get<const basic_json_t>(), which is why we still need the uncvref
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static_assert(not std::is_reference<T>::value, "get cannot be used with reference types, you might want to use get_ref");
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static_assert(std::is_default_constructible<U>::value,
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"Types must be DefaultConstructible when used with get");
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U ret;
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JSONSerializer<U>::from_json(*this, ret);
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// we cannot static_assert on ValueTypeCV being non-const, because
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// there is support for get<const basic_json_t>(), which is why we
|
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// still need the uncvref
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static_assert(not std::is_reference<ValueTypeCV>::value,
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"get() cannot be used with reference types, you might want to use get_ref()");
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static_assert(std::is_default_constructible<ValueType>::value,
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"types must be DefaultConstructible when used with get()");
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ValueType ret;
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JSONSerializer<ValueType>::from_json(*this, ret);
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return ret;
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}
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/*!
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@brief get overload for types than cannot be default constructed or copy constructed
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@brief get a value (explicit); special case
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|
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If @ref json_serializer<U> has both overloads of from_json, this one is chosen
|
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Explicit type conversion between the JSON value and a compatible value
|
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which is **not** [CopyConstructible](http://en.cppreference.com/w/cpp/concept/CopyConstructible)
|
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and **not** [DefaultConstructible](http://en.cppreference.com/w/cpp/concept/DefaultConstructible).
|
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The value is converted by calling the @ref json_serializer<ValueType>
|
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`from_json()` method.
|
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|
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The function is equivalent to executing
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@code {.cpp}
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return JSONSerializer<ValueTypeCV>::from_json(*this);
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@endcode
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|
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This overloads is chosen if:
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- U is not @ref basic_json
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- @ref json_serializer<U> has a from_json method of the form: U from_json(const @ref basic_json&);
|
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- @a ValueType is not @ref basic_json and
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- @ref json_serializer<ValueType> has a `from_json()` method of the form
|
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`ValueType from_json(const @ref basic_json&)`
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|
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@return a value of type U
|
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@note If @ref json_serializer<ValueType> has both overloads of
|
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`from_json()`, this one is chosen.
|
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|
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@throw what json_serializer<U> from_json method throws
|
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@tparam ValueTypeCV the provided value type
|
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@tparam ValueType the returned value type
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|
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@return copy of the JSON value, converted to @a ValueType
|
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|
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@throw what @ref json_serializer<ValueType> `from_json()` method throws
|
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|
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@since version 2.1.0
|
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*/
|
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template <
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typename T,
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typename U = detail::uncvref_t<T>,
|
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detail::enable_if_t<not std::is_same<basic_json_t, U>::value and
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typename ValueTypeCV,
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typename ValueType = detail::uncvref_t<ValueTypeCV>,
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detail::enable_if_t<not std::is_same<basic_json_t, ValueType>::value and
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detail::has_non_default_from_json<basic_json_t,
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U>::value, int> = 0 >
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U get() const noexcept(noexcept(JSONSerializer<T>::from_json(std::declval<const basic_json_t&>())))
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ValueType>::value, int> = 0 >
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ValueType get() const noexcept(noexcept(
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JSONSerializer<ValueTypeCV>::from_json(std::declval<const basic_json_t&>())))
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{
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static_assert(not std::is_reference<T>::value, "get cannot be used with reference types, you might want to use get_ref");
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return JSONSerializer<T>::from_json(*this);
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static_assert(not std::is_reference<ValueTypeCV>::value,
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"get() cannot be used with reference types, you might want to use get_ref()");
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return JSONSerializer<ValueTypeCV>::from_json(*this);
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}
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/*!
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|
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