Skip to content

J
json
Commit ebd3f458 by Pratik Chowdhury
Options

Added Support for Structured Bindings

For further details, read https://github.com/nlohmann/json/issues/1388 and https://blog.tartanllama.xyz/structured-bindings/
parent e73dfef6
Showing with 191 additions and 101 deletions
.gitignore
...@@ -22,3 +22,4 @@ benchmarks/files/numbers/*.json ...@@ -22,3 +22,4 @@ benchmarks/files/numbers/*.json
cmake-build-debug cmake-build-debug
test/test-* test/test-*
/.vs
include/nlohmann/detail/conversions/to_json.hpp
...@@ -290,9 +290,9 @@ void to_json(BasicJsonType& j, typename BasicJsonType::object_t&& obj) ...@@ -290,9 +290,9 @@ void to_json(BasicJsonType& j, typename BasicJsonType::object_t&& obj)
template < template <
typename BasicJsonType, typename T, std::size_t N, typename BasicJsonType, typename T, std::size_t N,
enable_if_t<not std::is_constructible<typename BasicJsonType::string_t, enable_if_t<not std::is_constructible<typename BasicJsonType::string_t,
const T (&)[N]>::value, const T(&)[N]>::value,
int> = 0 > int> = 0 >
void to_json(BasicJsonType& j, const T (&arr)[N]) void to_json(BasicJsonType& j, const T(&arr)[N])
{ {
external_constructor<value_t::array>::construct(j, arr); external_constructor<value_t::array>::construct(j, arr);
} }
...@@ -300,21 +300,21 @@ void to_json(BasicJsonType& j, const T (&arr)[N]) ...@@ -300,21 +300,21 @@ void to_json(BasicJsonType& j, const T (&arr)[N])
template<typename BasicJsonType, typename... Args> template<typename BasicJsonType, typename... Args>
void to_json(BasicJsonType& j, const std::pair<Args...>& p) void to_json(BasicJsonType& j, const std::pair<Args...>& p)
{ {
j = {p.first, p.second}; j = { p.first, p.second };
} }
// for https://github.com/nlohmann/json/pull/1134 // for https://github.com/nlohmann/json/pull/1134
template<typename BasicJsonType, typename T, template < typename BasicJsonType, typename T,
enable_if_t<std::is_same<T, typename iteration_proxy<typename BasicJsonType::iterator>::iteration_proxy_internal>::value, int> = 0> enable_if_t<std::is_same<T, iteration_proxy_value<typename BasicJsonType::iterator>>::value, int> = 0>
void to_json(BasicJsonType& j, const T& b) void to_json(BasicJsonType& j, const T& b)
{ {
j = {{b.key(), b.value()}}; j = { {b.key(), b.value()} };
} }
template<typename BasicJsonType, typename Tuple, std::size_t... Idx> template<typename BasicJsonType, typename Tuple, std::size_t... Idx>
void to_json_tuple_impl(BasicJsonType& j, const Tuple& t, index_sequence<Idx...> /*unused*/) void to_json_tuple_impl(BasicJsonType& j, const Tuple& t, index_sequence<Idx...> /*unused*/)
{ {
j = {std::get<Idx>(t)...}; j = { std::get<Idx>(t)... };
} }
template<typename BasicJsonType, typename... Args> template<typename BasicJsonType, typename... Args>
......
include/nlohmann/detail/iterators/iter_impl.hpp
...@@ -17,24 +17,21 @@ namespace detail ...@@ -17,24 +17,21 @@ namespace detail
{ {
// forward declare, to be able to friend it later on // forward declare, to be able to friend it later on
template<typename IteratorType> class iteration_proxy; template<typename IteratorType> class iteration_proxy;
template<typename IteratorType> class iteration_proxy_value;
/*! /*!
@brief a template for a bidirectional iterator for the @ref basic_json class @brief a template for a bidirectional iterator for the @ref basic_json class
This class implements a both iterators (iterator and const_iterator) for the This class implements a both iterators (iterator and const_iterator) for the
@ref basic_json class. @ref basic_json class.
@note An iterator is called *initialized* when a pointer to a JSON value has @note An iterator is called *initialized* when a pointer to a JSON value has
been set (e.g., by a constructor or a copy assignment). If the iterator is been set (e.g., by a constructor or a copy assignment). If the iterator is
default-constructed, it is *uninitialized* and most methods are undefined. default-constructed, it is *uninitialized* and most methods are undefined.
**The library uses assertions to detect calls on uninitialized iterators.** **The library uses assertions to detect calls on uninitialized iterators.**
@requirement The class satisfies the following concept requirements: @requirement The class satisfies the following concept requirements:
- -
[BidirectionalIterator](https://en.cppreference.com/w/cpp/named_req/BidirectionalIterator): [BidirectionalIterator](https://en.cppreference.com/w/cpp/named_req/BidirectionalIterator):
The iterator that can be moved can be moved in both directions (i.e. The iterator that can be moved can be moved in both directions (i.e.
incremented and decremented). incremented and decremented).
@since version 1.0.0, simplified in version 2.0.9, change to bidirectional @since version 1.0.0, simplified in version 2.0.9, change to bidirectional
iterators in version 3.0.0 (see https://github.com/nlohmann/json/issues/593) iterators in version 3.0.0 (see https://github.com/nlohmann/json/issues/593)
*/ */
...@@ -45,6 +42,7 @@ class iter_impl ...@@ -45,6 +42,7 @@ class iter_impl
friend iter_impl<typename std::conditional<std::is_const<BasicJsonType>::value, typename std::remove_const<BasicJsonType>::type, const BasicJsonType>::type>; friend iter_impl<typename std::conditional<std::is_const<BasicJsonType>::value, typename std::remove_const<BasicJsonType>::type, const BasicJsonType>::type>;
friend BasicJsonType; friend BasicJsonType;
friend iteration_proxy<iter_impl>; friend iteration_proxy<iter_impl>;
friend iteration_proxy_value<iter_impl>;
using object_t = typename BasicJsonType::object_t; using object_t = typename BasicJsonType::object_t;
using array_t = typename BasicJsonType::array_t; using array_t = typename BasicJsonType::array_t;
......
include/nlohmann/detail/iterators/iteration_proxy.hpp
...@@ -3,25 +3,22 @@ ...@@ -3,25 +3,22 @@
#include <cstddef> // size_t #include <cstddef> // size_t
#include <string> // string, to_string #include <string> // string, to_string
#include <iterator> // input_iterator_tag #include <iterator> // input_iterator_tag
#include <tuple> // tuple_size, get, tuple_element
#include <nlohmann/detail/value_t.hpp> #include <nlohmann/detail/value_t.hpp>
#include <nlohmann/detail/meta/type_traits.hpp>
namespace nlohmann namespace nlohmann
{ {
namespace detail namespace detail
{ {
/// proxy class for the items() function template <typename IteratorType> class iteration_proxy_value
template<typename IteratorType> class iteration_proxy
{ {
private:
/// helper class for iteration
class iteration_proxy_internal
{
public: public:
using difference_type = std::ptrdiff_t; using difference_type = std::ptrdiff_t;
using value_type = iteration_proxy_internal; using value_type = iteration_proxy_value;
using pointer = iteration_proxy_internal*; using pointer = value_type * ;
using reference = iteration_proxy_internal&; using reference = value_type & ;
using iterator_category = std::input_iterator_tag; using iterator_category = std::input_iterator_tag;
private: private:
...@@ -37,16 +34,16 @@ template<typename IteratorType> class iteration_proxy ...@@ -37,16 +34,16 @@ template<typename IteratorType> class iteration_proxy
const std::string empty_str = ""; const std::string empty_str = "";
public: public:
explicit iteration_proxy_internal(IteratorType it) noexcept : anchor(it) {} explicit iteration_proxy_value(IteratorType it) noexcept : anchor(it) {}
/// dereference operator (needed for range-based for) /// dereference operator (needed for range-based for)
iteration_proxy_internal& operator*() iteration_proxy_value& operator*()
{ {
return *this; return *this;
} }
/// increment operator (needed for range-based for) /// increment operator (needed for range-based for)
iteration_proxy_internal& operator++() iteration_proxy_value& operator++()
{ {
++anchor; ++anchor;
++array_index; ++array_index;
...@@ -55,13 +52,13 @@ template<typename IteratorType> class iteration_proxy ...@@ -55,13 +52,13 @@ template<typename IteratorType> class iteration_proxy
} }
/// equality operator (needed for InputIterator) /// equality operator (needed for InputIterator)
bool operator==(const iteration_proxy_internal& o) const noexcept bool operator==(const iteration_proxy_value& o) const noexcept
{ {
return anchor == o.anchor; return anchor == o.anchor;
} }
/// inequality operator (needed for range-based for) /// inequality operator (needed for range-based for)
bool operator!=(const iteration_proxy_internal& o) const noexcept bool operator!=(const iteration_proxy_value& o) const noexcept
{ {
return anchor != o.anchor; return anchor != o.anchor;
} }
...@@ -99,8 +96,12 @@ template<typename IteratorType> class iteration_proxy ...@@ -99,8 +96,12 @@ template<typename IteratorType> class iteration_proxy
{ {
return anchor.value(); return anchor.value();
} }
}; };
/// proxy class for the items() function
template<typename IteratorType> class iteration_proxy
{
private:
/// the container to iterate /// the container to iterate
typename IteratorType::reference container; typename IteratorType::reference container;
...@@ -110,16 +111,52 @@ template<typename IteratorType> class iteration_proxy ...@@ -110,16 +111,52 @@ template<typename IteratorType> class iteration_proxy
: container(cont) {} : container(cont) {}
/// return iterator begin (needed for range-based for) /// return iterator begin (needed for range-based for)
iteration_proxy_internal begin() noexcept iteration_proxy_value<IteratorType> begin() noexcept
{ {
return iteration_proxy_internal(container.begin()); return iteration_proxy_value<IteratorType>(container.begin());
} }
/// return iterator end (needed for range-based for) /// return iterator end (needed for range-based for)
iteration_proxy_internal end() noexcept iteration_proxy_value<IteratorType> end() noexcept
{ {
return iteration_proxy_internal(container.end()); return iteration_proxy_value<IteratorType>(container.end());
} }
}; };
// Structured Bindings Support
// For further reference see https://blog.tartanllama.xyz/structured-bindings/
// And see https://github.com/nlohmann/json/pull/1391
template <std::size_t N, typename IteratorType, enable_if_t<N == 0, int> = 0>
auto get(const nlohmann::detail::iteration_proxy_value<IteratorType>& i) -> decltype(i.key())
{
return i.key();
}
// Structured Bindings Support
// For further reference see https://blog.tartanllama.xyz/structured-bindings/
// And see https://github.com/nlohmann/json/pull/1391
template <std::size_t N, typename IteratorType, enable_if_t<N == 1, int> = 0>
auto get(const nlohmann::detail::iteration_proxy_value<IteratorType>& i) -> decltype(i.value())
{
return i.value();
}
} // namespace detail } // namespace detail
} // namespace nlohmann } // namespace nlohmann
// The Addition to the STD Namespace is required to add
// Structured Bindings Support to the iteration_proxy_value class
// For further reference see https://blog.tartanllama.xyz/structured-bindings/
// And see https://github.com/nlohmann/json/pull/1391
namespace std
{
template <typename IteratorType>
struct tuple_size<::nlohmann::detail::iteration_proxy_value<IteratorType>>
: std::integral_constant<std::size_t, 2> {};
template <std::size_t N, typename IteratorType>
struct tuple_element <
N, ::nlohmann::detail::iteration_proxy_value<IteratorType >>
{
using type = decltype(
get<N>(std::declval <
::nlohmann::detail::iteration_proxy_value<IteratorType >> ()));
};
}
\ No newline at end of file
single_include/nlohmann/json.hpp
...@@ -1594,26 +1594,24 @@ constexpr const auto& from_json = detail::static_const<detail::from_json_fn>::va ...@@ -1594,26 +1594,24 @@ constexpr const auto& from_json = detail::static_const<detail::from_json_fn>::va
#include <cstddef> // size_t #include <cstddef> // size_t
#include <string> // string, to_string #include <string> // string, to_string
#include <iterator> // input_iterator_tag #include <iterator> // input_iterator_tag
#include <tuple> // tuple_size, get, tuple_element
// #include <nlohmann/detail/value_t.hpp> // #include <nlohmann/detail/value_t.hpp>
// #include <nlohmann/detail/meta/type_traits.hpp>
namespace nlohmann namespace nlohmann
{ {
namespace detail namespace detail
{ {
/// proxy class for the items() function template <typename IteratorType> class iteration_proxy_value
template<typename IteratorType> class iteration_proxy
{ {
private:
/// helper class for iteration
class iteration_proxy_internal
{
public: public:
using difference_type = std::ptrdiff_t; using difference_type = std::ptrdiff_t;
using value_type = iteration_proxy_internal; using value_type = iteration_proxy_value;
using pointer = iteration_proxy_internal*; using pointer = value_type * ;
using reference = iteration_proxy_internal&; using reference = value_type & ;
using iterator_category = std::input_iterator_tag; using iterator_category = std::input_iterator_tag;
private: private:
...@@ -1629,16 +1627,16 @@ template<typename IteratorType> class iteration_proxy ...@@ -1629,16 +1627,16 @@ template<typename IteratorType> class iteration_proxy
const std::string empty_str = ""; const std::string empty_str = "";
public: public:
explicit iteration_proxy_internal(IteratorType it) noexcept : anchor(it) {} explicit iteration_proxy_value(IteratorType it) noexcept : anchor(it) {}
/// dereference operator (needed for range-based for) /// dereference operator (needed for range-based for)
iteration_proxy_internal& operator*() iteration_proxy_value& operator*()
{ {
return *this; return *this;
} }
/// increment operator (needed for range-based for) /// increment operator (needed for range-based for)
iteration_proxy_internal& operator++() iteration_proxy_value& operator++()
{ {
++anchor; ++anchor;
++array_index; ++array_index;
...@@ -1647,13 +1645,13 @@ template<typename IteratorType> class iteration_proxy ...@@ -1647,13 +1645,13 @@ template<typename IteratorType> class iteration_proxy
} }
/// equality operator (needed for InputIterator) /// equality operator (needed for InputIterator)
bool operator==(const iteration_proxy_internal& o) const noexcept bool operator==(const iteration_proxy_value& o) const noexcept
{ {
return anchor == o.anchor; return anchor == o.anchor;
} }
/// inequality operator (needed for range-based for) /// inequality operator (needed for range-based for)
bool operator!=(const iteration_proxy_internal& o) const noexcept bool operator!=(const iteration_proxy_value& o) const noexcept
{ {
return anchor != o.anchor; return anchor != o.anchor;
} }
...@@ -1691,8 +1689,12 @@ template<typename IteratorType> class iteration_proxy ...@@ -1691,8 +1689,12 @@ template<typename IteratorType> class iteration_proxy
{ {
return anchor.value(); return anchor.value();
} }
}; };
/// proxy class for the items() function
template<typename IteratorType> class iteration_proxy
{
private:
/// the container to iterate /// the container to iterate
typename IteratorType::reference container; typename IteratorType::reference container;
...@@ -1702,20 +1704,55 @@ template<typename IteratorType> class iteration_proxy ...@@ -1702,20 +1704,55 @@ template<typename IteratorType> class iteration_proxy
: container(cont) {} : container(cont) {}
/// return iterator begin (needed for range-based for) /// return iterator begin (needed for range-based for)
iteration_proxy_internal begin() noexcept iteration_proxy_value<IteratorType> begin() noexcept
{ {
return iteration_proxy_internal(container.begin()); return iteration_proxy_value<IteratorType>(container.begin());
} }
/// return iterator end (needed for range-based for) /// return iterator end (needed for range-based for)
iteration_proxy_internal end() noexcept iteration_proxy_value<IteratorType> end() noexcept
{ {
return iteration_proxy_internal(container.end()); return iteration_proxy_value<IteratorType>(container.end());
} }
}; };
// Structured Bindings Support
// For further reference see https://blog.tartanllama.xyz/structured-bindings/
// And see https://github.com/nlohmann/json/pull/1391
template <std::size_t N, typename IteratorType, enable_if_t<N == 0, int> = 0>
auto get(const nlohmann::detail::iteration_proxy_value<IteratorType>& i) -> decltype(i.key())
{
return i.key();
}
// Structured Bindings Support
// For further reference see https://blog.tartanllama.xyz/structured-bindings/
// And see https://github.com/nlohmann/json/pull/1391
template <std::size_t N, typename IteratorType, enable_if_t<N == 1, int> = 0>
auto get(const nlohmann::detail::iteration_proxy_value<IteratorType>& i) -> decltype(i.value())
{
return i.value();
}
} // namespace detail } // namespace detail
} // namespace nlohmann } // namespace nlohmann
// The Addition to the STD Namespace is required to add
// Structured Bindings Support to the iteration_proxy_value class
// For further reference see https://blog.tartanllama.xyz/structured-bindings/
// And see https://github.com/nlohmann/json/pull/1391
namespace std
{
template <typename IteratorType>
struct tuple_size<::nlohmann::detail::iteration_proxy_value<IteratorType>>
: std::integral_constant<std::size_t, 2> {};
template <std::size_t N, typename IteratorType>
struct tuple_element <
N, ::nlohmann::detail::iteration_proxy_value<IteratorType >>
{
using type = decltype(
get<N>(std::declval <
::nlohmann::detail::iteration_proxy_value<IteratorType >> ()));
};
}
namespace nlohmann namespace nlohmann
{ {
...@@ -1994,9 +2031,9 @@ void to_json(BasicJsonType& j, typename BasicJsonType::object_t&& obj) ...@@ -1994,9 +2031,9 @@ void to_json(BasicJsonType& j, typename BasicJsonType::object_t&& obj)
template < template <
typename BasicJsonType, typename T, std::size_t N, typename BasicJsonType, typename T, std::size_t N,
enable_if_t<not std::is_constructible<typename BasicJsonType::string_t, enable_if_t<not std::is_constructible<typename BasicJsonType::string_t,
const T (&)[N]>::value, const T(&)[N]>::value,
int> = 0 > int> = 0 >
void to_json(BasicJsonType& j, const T (&arr)[N]) void to_json(BasicJsonType& j, const T(&arr)[N])
{ {
external_constructor<value_t::array>::construct(j, arr); external_constructor<value_t::array>::construct(j, arr);
} }
...@@ -2004,21 +2041,21 @@ void to_json(BasicJsonType& j, const T (&arr)[N]) ...@@ -2004,21 +2041,21 @@ void to_json(BasicJsonType& j, const T (&arr)[N])
template<typename BasicJsonType, typename... Args> template<typename BasicJsonType, typename... Args>
void to_json(BasicJsonType& j, const std::pair<Args...>& p) void to_json(BasicJsonType& j, const std::pair<Args...>& p)
{ {
j = {p.first, p.second}; j = { p.first, p.second };
} }
// for https://github.com/nlohmann/json/pull/1134 // for https://github.com/nlohmann/json/pull/1134
template<typename BasicJsonType, typename T, template < typename BasicJsonType, typename T,
enable_if_t<std::is_same<T, typename iteration_proxy<typename BasicJsonType::iterator>::iteration_proxy_internal>::value, int> = 0> enable_if_t<std::is_same<T, iteration_proxy_value<typename BasicJsonType::iterator>>::value, int> = 0>
void to_json(BasicJsonType& j, const T& b) void to_json(BasicJsonType& j, const T& b)
{ {
j = {{b.key(), b.value()}}; j = { {b.key(), b.value()} };
} }
template<typename BasicJsonType, typename Tuple, std::size_t... Idx> template<typename BasicJsonType, typename Tuple, std::size_t... Idx>
void to_json_tuple_impl(BasicJsonType& j, const Tuple& t, index_sequence<Idx...> /*unused*/) void to_json_tuple_impl(BasicJsonType& j, const Tuple& t, index_sequence<Idx...> /*unused*/)
{ {
j = {std::get<Idx>(t)...}; j = { std::get<Idx>(t)... };
} }
template<typename BasicJsonType, typename... Args> template<typename BasicJsonType, typename... Args>
...@@ -5492,24 +5529,21 @@ namespace detail ...@@ -5492,24 +5529,21 @@ namespace detail
{ {
// forward declare, to be able to friend it later on // forward declare, to be able to friend it later on
template<typename IteratorType> class iteration_proxy; template<typename IteratorType> class iteration_proxy;
template<typename IteratorType> class iteration_proxy_value;
/*! /*!
@brief a template for a bidirectional iterator for the @ref basic_json class @brief a template for a bidirectional iterator for the @ref basic_json class
This class implements a both iterators (iterator and const_iterator) for the This class implements a both iterators (iterator and const_iterator) for the
@ref basic_json class. @ref basic_json class.
@note An iterator is called *initialized* when a pointer to a JSON value has @note An iterator is called *initialized* when a pointer to a JSON value has
been set (e.g., by a constructor or a copy assignment). If the iterator is been set (e.g., by a constructor or a copy assignment). If the iterator is
default-constructed, it is *uninitialized* and most methods are undefined. default-constructed, it is *uninitialized* and most methods are undefined.
**The library uses assertions to detect calls on uninitialized iterators.** **The library uses assertions to detect calls on uninitialized iterators.**
@requirement The class satisfies the following concept requirements: @requirement The class satisfies the following concept requirements:
- -
[BidirectionalIterator](https://en.cppreference.com/w/cpp/named_req/BidirectionalIterator): [BidirectionalIterator](https://en.cppreference.com/w/cpp/named_req/BidirectionalIterator):
The iterator that can be moved can be moved in both directions (i.e. The iterator that can be moved can be moved in both directions (i.e.
incremented and decremented). incremented and decremented).
@since version 1.0.0, simplified in version 2.0.9, change to bidirectional @since version 1.0.0, simplified in version 2.0.9, change to bidirectional
iterators in version 3.0.0 (see https://github.com/nlohmann/json/issues/593) iterators in version 3.0.0 (see https://github.com/nlohmann/json/issues/593)
*/ */
...@@ -5520,6 +5554,7 @@ class iter_impl ...@@ -5520,6 +5554,7 @@ class iter_impl
friend iter_impl<typename std::conditional<std::is_const<BasicJsonType>::value, typename std::remove_const<BasicJsonType>::type, const BasicJsonType>::type>; friend iter_impl<typename std::conditional<std::is_const<BasicJsonType>::value, typename std::remove_const<BasicJsonType>::type, const BasicJsonType>::type>;
friend BasicJsonType; friend BasicJsonType;
friend iteration_proxy<iter_impl>; friend iteration_proxy<iter_impl>;
friend iteration_proxy_value<iter_impl>;
using object_t = typename BasicJsonType::object_t; using object_t = typename BasicJsonType::object_t;
using array_t = typename BasicJsonType::array_t; using array_t = typename BasicJsonType::array_t;
...@@ -6087,7 +6122,6 @@ class iter_impl ...@@ -6087,7 +6122,6 @@ class iter_impl
}; };
} // namespace detail } // namespace detail
} // namespace nlohmann } // namespace nlohmann
// #include <nlohmann/detail/iterators/iteration_proxy.hpp> // #include <nlohmann/detail/iterators/iteration_proxy.hpp>
// #include <nlohmann/detail/iterators/json_reverse_iterator.hpp> // #include <nlohmann/detail/iterators/json_reverse_iterator.hpp>
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment