From 0ba98b6fe08f8f8e3060be1f8f3f3b7c4c23af3d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9o=20DELRIEU?= <delrieutheo@gmail.com>
Date: Sun, 9 Jul 2017 16:53:36 +0200
Subject: [PATCH] move internal_iterator/iter_impl/iteration_proxy outside of
basic_json
---
src/json.hpp | 1490 +++++++++++++++++++++++++-------------------------
1 file changed, 752 insertions(+), 738 deletions(-)
diff --git a/src/json.hpp b/src/json.hpp
index 76359eaa..1e75b5e2 100644
--- a/src/json.hpp
+++ b/src/json.hpp
@@ -490,6 +490,10 @@ inline bool operator<(const value_t lhs, const value_t rhs) noexcept
// helpers //
/////////////
+template <typename> struct is_basic_json : std::false_type {};
+
+NLOHMANN_BASIC_JSON_TPL_DECLARATION struct is_basic_json<NLOHMANN_BASIC_JSON_TPL> : std::true_type {};
+
// alias templates to reduce boilerplate
template<bool B, typename T = void>
using enable_if_t = typename std::enable_if<B, T>::type;
@@ -3715,6 +3719,746 @@ class primitive_iterator_t
/// iterator as signed integer type
difference_type m_it = std::numeric_limits<std::ptrdiff_t>::denorm_min();
};
+
+/*!
+@brief an iterator value
+
+@note This structure could easily be a union, but MSVC currently does not
+allow unions members with complex constructors, see
+https://github.com/nlohmann/json/pull/105.
+*/
+template <typename BasicJsonType> struct internal_iterator
+{
+ /// iterator for JSON objects
+ typename BasicJsonType::object_t::iterator object_iterator;
+ /// iterator for JSON arrays
+ typename BasicJsonType::array_t::iterator array_iterator;
+ /// generic iterator for all other types
+ primitive_iterator_t primitive_iterator;
+
+ /// create an uninitialized internal_iterator
+ internal_iterator() noexcept : object_iterator(),
+ array_iterator(),
+ primitive_iterator() {}
+};
+
+template <typename IteratorType> class iteration_proxy;
+
+/*!
+@brief a template for a random access iterator for the @ref basic_json class
+
+This class implements a both iterators (iterator and const_iterator) for the
+@ref basic_json class.
+
+@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 default-constructed, it is *uninitialized* and most
+ methods are undefined. **The library uses assertions to detect calls
+ on uninitialized iterators.**
+
+@requirement The class satisfies the following concept requirements:
+-
+[RandomAccessIterator](http://en.cppreference.com/w/cpp/concept/RandomAccessIterator):
+ The iterator that can be moved to point (forward and backward) to any
+ element in constant time.
+
+@since version 1.0.0, simplified in version 2.0.9
+*/
+template <typename BasicJsonType>
+class iter_impl : public std::iterator<std::random_access_iterator_tag, BasicJsonType>
+{
+ /// allow basic_json to access private members
+ friend iter_impl<typename std::conditional<std::is_const<BasicJsonType>::value, typename std::remove_const<BasicJsonType>::type, const BasicJsonType>::type>;
+ friend BasicJsonType;
+ friend iteration_proxy<iter_impl>;
+
+ using object_t = typename BasicJsonType::object_t;
+ using array_t = typename BasicJsonType::array_t;
+ // make sure BasicJsonType is basic_json or const basic_json
+ static_assert(is_basic_json<typename std::remove_const<BasicJsonType>::type>::value,
+ "iter_impl only accepts (const) basic_json");
+
+ public:
+ /// the type of the values when the iterator is dereferenced
+ using value_type = typename BasicJsonType::value_type;
+ /// a type to represent differences between iterators
+ using difference_type = typename BasicJsonType::difference_type;
+ /// defines a pointer to the type iterated over (value_type)
+ using pointer = typename std::conditional<std::is_const<BasicJsonType>::value,
+ typename BasicJsonType::const_pointer,
+ typename BasicJsonType::pointer>::type;
+ /// defines a reference to the type iterated over (value_type)
+ using reference =
+ typename std::conditional<std::is_const<BasicJsonType>::value,
+ typename BasicJsonType::const_reference,
+ typename BasicJsonType::reference>::type;
+ /// the category of the iterator
+ using iterator_category = std::bidirectional_iterator_tag;
+
+ /// default constructor
+ iter_impl() = default;
+
+ /*!
+ @brief constructor for a given JSON instance
+ @param[in] object pointer to a JSON object for this iterator
+ @pre object != nullptr
+ @post The iterator is initialized; i.e. `m_object != nullptr`.
+ */
+ explicit iter_impl(pointer object) noexcept : m_object(object)
+ {
+ assert(m_object != nullptr);
+
+ switch (m_object->m_type)
+ {
+ case value_t::object:
+ {
+ m_it.object_iterator = typename object_t::iterator();
+ break;
+ }
+
+ case value_t::array:
+ {
+ m_it.array_iterator = typename array_t::iterator();
+ break;
+ }
+
+ default:
+ {
+ m_it.primitive_iterator = primitive_iterator_t();
+ break;
+ }
+ }
+ }
+
+ /*!
+ @note The conventional copy constructor and copy assignment are
+ implicitly defined.
+ Combined with the following converting constructor and assignment,
+ they support: copy from iterator to iterator,
+ copy from const iterator to const iterator,
+ and conversion from iterator to const iterator.
+ However conversion from const iterator to iterator is not defined.
+ */
+
+ /*!
+ @brief converting constructor
+ @param[in] other non-const iterator to copy from
+ @note It is not checked whether @a other is initialized.
+ */
+ iter_impl(const iter_impl<typename std::remove_const<BasicJsonType>::type>& other) noexcept
+ : m_object(other.m_object),
+ m_it(other.m_it) {}
+
+ /*!
+ @brief converting assignment
+ @param[in,out] other non-const iterator to copy from
+ @return const/non-const iterator
+ @note It is not checked whether @a other is initialized.
+ */
+ iter_impl& operator=(const iter_impl<typename std::remove_const<BasicJsonType>::type>& other) noexcept
+ {
+ m_object = other.m_object;
+ m_it = other.m_it;
+ return *this;
+ }
+
+ private:
+ /*!
+ @brief set the iterator to the first value
+ @pre The iterator is initialized; i.e. `m_object != nullptr`.
+ */
+ void set_begin() noexcept
+ {
+ assert(m_object != nullptr);
+
+ switch (m_object->m_type)
+ {
+ case value_t::object:
+ {
+ m_it.object_iterator = m_object->m_value.object->begin();
+ break;
+ }
+
+ case value_t::array:
+ {
+ m_it.array_iterator = m_object->m_value.array->begin();
+ break;
+ }
+
+ case value_t::null:
+ {
+ // set to end so begin()==end() is true: null is empty
+ m_it.primitive_iterator.set_end();
+ break;
+ }
+
+ default:
+ {
+ m_it.primitive_iterator.set_begin();
+ break;
+ }
+ }
+ }
+
+ /*!
+ @brief set the iterator past the last value
+ @pre The iterator is initialized; i.e. `m_object != nullptr`.
+ */
+ void set_end() noexcept
+ {
+ assert(m_object != nullptr);
+
+ switch (m_object->m_type)
+ {
+ case value_t::object:
+ {
+ m_it.object_iterator = m_object->m_value.object->end();
+ break;
+ }
+
+ case value_t::array:
+ {
+ m_it.array_iterator = m_object->m_value.array->end();
+ break;
+ }
+
+ default:
+ {
+ m_it.primitive_iterator.set_end();
+ break;
+ }
+ }
+ }
+
+ public:
+ /*!
+ @brief return a reference to the value pointed to by the iterator
+ @pre The iterator is initialized; i.e. `m_object != nullptr`.
+ */
+ reference operator*() const
+ {
+ assert(m_object != nullptr);
+
+ switch (m_object->m_type)
+ {
+ case value_t::object:
+ {
+ assert(m_it.object_iterator != m_object->m_value.object->end());
+ return m_it.object_iterator->second;
+ }
+
+ case value_t::array:
+ {
+ assert(m_it.array_iterator != m_object->m_value.array->end());
+ return *m_it.array_iterator;
+ }
+
+ case value_t::null:
+ {
+ JSON_THROW(invalid_iterator::create(214, "cannot get value"));
+ }
+
+ default:
+ {
+ if (m_it.primitive_iterator.is_begin())
+ {
+ return *m_object;
+ }
+
+ JSON_THROW(invalid_iterator::create(214, "cannot get value"));
+ }
+ }
+ }
+
+ /*!
+ @brief dereference the iterator
+ @pre The iterator is initialized; i.e. `m_object != nullptr`.
+ */
+ pointer operator->() const
+ {
+ assert(m_object != nullptr);
+
+ switch (m_object->m_type)
+ {
+ case value_t::object:
+ {
+ assert(m_it.object_iterator != m_object->m_value.object->end());
+ return &(m_it.object_iterator->second);
+ }
+
+ case value_t::array:
+ {
+ assert(m_it.array_iterator != m_object->m_value.array->end());
+ return &*m_it.array_iterator;
+ }
+
+ default:
+ {
+ if (m_it.primitive_iterator.is_begin())
+ {
+ return m_object;
+ }
+
+ JSON_THROW(invalid_iterator::create(214, "cannot get value"));
+ }
+ }
+ }
+
+ /*!
+ @brief post-increment (it++)
+ @pre The iterator is initialized; i.e. `m_object != nullptr`.
+ */
+ iter_impl operator++(int)
+ {
+ auto result = *this;
+ ++(*this);
+ return result;
+ }
+
+ /*!
+ @brief pre-increment (++it)
+ @pre The iterator is initialized; i.e. `m_object != nullptr`.
+ */
+ iter_impl& operator++()
+ {
+ assert(m_object != nullptr);
+
+ switch (m_object->m_type)
+ {
+ case value_t::object:
+ {
+ std::advance(m_it.object_iterator, 1);
+ break;
+ }
+
+ case value_t::array:
+ {
+ std::advance(m_it.array_iterator, 1);
+ break;
+ }
+
+ default:
+ {
+ ++m_it.primitive_iterator;
+ break;
+ }
+ }
+
+ return *this;
+ }
+
+ /*!
+ @brief post-decrement (it--)
+ @pre The iterator is initialized; i.e. `m_object != nullptr`.
+ */
+ iter_impl operator--(int)
+ {
+ auto result = *this;
+ --(*this);
+ return result;
+ }
+
+ /*!
+ @brief pre-decrement (--it)
+ @pre The iterator is initialized; i.e. `m_object != nullptr`.
+ */
+ iter_impl& operator--()
+ {
+ assert(m_object != nullptr);
+
+ switch (m_object->m_type)
+ {
+ case value_t::object:
+ {
+ std::advance(m_it.object_iterator, -1);
+ break;
+ }
+
+ case value_t::array:
+ {
+ std::advance(m_it.array_iterator, -1);
+ break;
+ }
+
+ default:
+ {
+ --m_it.primitive_iterator;
+ break;
+ }
+ }
+
+ return *this;
+ }
+
+ /*!
+ @brief comparison: equal
+ @pre The iterator is initialized; i.e. `m_object != nullptr`.
+ */
+ bool operator==(const iter_impl& other) const
+ {
+ // if objects are not the same, the comparison is undefined
+ if (m_object != other.m_object)
+ {
+ JSON_THROW(invalid_iterator::create(
+ 212, "cannot compare iterators of different containers"));
+ }
+
+ assert(m_object != nullptr);
+
+ switch (m_object->m_type)
+ {
+ case value_t::object:
+ {
+ return (m_it.object_iterator == other.m_it.object_iterator);
+ }
+
+ case value_t::array:
+ {
+ return (m_it.array_iterator == other.m_it.array_iterator);
+ }
+
+ default:
+ {
+ return (m_it.primitive_iterator == other.m_it.primitive_iterator);
+ }
+ }
+ }
+
+ /*!
+ @brief comparison: not equal
+ @pre The iterator is initialized; i.e. `m_object != nullptr`.
+ */
+ bool operator!=(const iter_impl& other) const
+ {
+ return not operator==(other);
+ }
+
+ /*!
+ @brief comparison: smaller
+ @pre The iterator is initialized; i.e. `m_object != nullptr`.
+ */
+ bool operator<(const iter_impl& other) const
+ {
+ // if objects are not the same, the comparison is undefined
+ if (m_object != other.m_object)
+ {
+ JSON_THROW(invalid_iterator::create(
+ 212, "cannot compare iterators of different containers"));
+ }
+
+ assert(m_object != nullptr);
+
+ switch (m_object->m_type)
+ {
+ case value_t::object:
+ {
+ JSON_THROW(invalid_iterator::create(
+ 213, "cannot compare order of object iterators"));
+ }
+
+ case value_t::array:
+ {
+ return (m_it.array_iterator < other.m_it.array_iterator);
+ }
+
+ default:
+ {
+ return (m_it.primitive_iterator < other.m_it.primitive_iterator);
+ }
+ }
+ }
+
+ /*!
+ @brief comparison: less than or equal
+ @pre The iterator is initialized; i.e. `m_object != nullptr`.
+ */
+ bool operator<=(const iter_impl& other) const
+ {
+ return not other.operator < (*this);
+ }
+
+ /*!
+ @brief comparison: greater than
+ @pre The iterator is initialized; i.e. `m_object != nullptr`.
+ */
+ bool operator>(const iter_impl& other) const
+ {
+ return not operator<=(other);
+ }
+
+ /*!
+ @brief comparison: greater than or equal
+ @pre The iterator is initialized; i.e. `m_object != nullptr`.
+ */
+ bool operator>=(const iter_impl& other) const
+ {
+ return not operator<(other);
+ }
+
+ /*!
+ @brief add to iterator
+ @pre The iterator is initialized; i.e. `m_object != nullptr`.
+ */
+ iter_impl& operator+=(difference_type i)
+ {
+ assert(m_object != nullptr);
+
+ switch (m_object->m_type)
+ {
+ case value_t::object:
+ {
+ JSON_THROW(invalid_iterator::create(
+ 209, "cannot use offsets with object iterators"));
+ }
+
+ case value_t::array:
+ {
+ std::advance(m_it.array_iterator, i);
+ break;
+ }
+
+ default:
+ {
+ m_it.primitive_iterator += i;
+ break;
+ }
+ }
+
+ return *this;
+ }
+
+ /*!
+ @brief subtract from iterator
+ @pre The iterator is initialized; i.e. `m_object != nullptr`.
+ */
+ iter_impl& operator-=(difference_type i)
+ {
+ return operator+=(-i);
+ }
+
+ /*!
+ @brief add to iterator
+ @pre The iterator is initialized; i.e. `m_object != nullptr`.
+ */
+ iter_impl operator+(difference_type i) const
+ {
+ auto result = *this;
+ result += i;
+ return result;
+ }
+
+ /*!
+ @brief addition of distance and iterator
+ @pre The iterator is initialized; i.e. `m_object != nullptr`.
+ */
+ friend iter_impl operator+(difference_type i, const iter_impl& it)
+ {
+ auto result = it;
+ result += i;
+ return result;
+ }
+
+ /*!
+ @brief subtract from iterator
+ @pre The iterator is initialized; i.e. `m_object != nullptr`.
+ */
+ iter_impl operator-(difference_type i) const
+ {
+ auto result = *this;
+ result -= i;
+ return result;
+ }
+
+ /*!
+ @brief return difference
+ @pre The iterator is initialized; i.e. `m_object != nullptr`.
+ */
+ difference_type operator-(const iter_impl& other) const
+ {
+ assert(m_object != nullptr);
+
+ switch (m_object->m_type)
+ {
+ case value_t::object:
+ {
+ JSON_THROW(invalid_iterator::create(
+ 209, "cannot use offsets with object iterators"));
+ }
+
+ case value_t::array:
+ {
+ return m_it.array_iterator - other.m_it.array_iterator;
+ }
+
+ default:
+ {
+ return m_it.primitive_iterator - other.m_it.primitive_iterator;
+ }
+ }
+ }
+
+ /*!
+ @brief access to successor
+ @pre The iterator is initialized; i.e. `m_object != nullptr`.
+ */
+ reference operator[](difference_type n) const
+ {
+ assert(m_object != nullptr);
+
+ switch (m_object->m_type)
+ {
+ case value_t::object:
+ {
+ JSON_THROW(invalid_iterator::create(
+ 208, "cannot use operator[] for object iterators"));
+ }
+
+ case value_t::array:
+ {
+ return *std::next(m_it.array_iterator, n);
+ }
+
+ case value_t::null:
+ {
+ JSON_THROW(invalid_iterator::create(214, "cannot get value"));
+ }
+
+ default:
+ {
+ if (m_it.primitive_iterator.get_value() == -n)
+ {
+ return *m_object;
+ }
+
+ JSON_THROW(invalid_iterator::create(214, "cannot get value"));
+ }
+ }
+ }
+
+ /*!
+ @brief return the key of an object iterator
+ @pre The iterator is initialized; i.e. `m_object != nullptr`.
+ */
+ typename object_t::key_type key() const
+ {
+ assert(m_object != nullptr);
+
+ if (m_object->is_object())
+ {
+ return m_it.object_iterator->first;
+ }
+
+ JSON_THROW(invalid_iterator::create(
+ 207, "cannot use key() for non-object iterators"));
+ }
+
+ /*!
+ @brief return the value of an iterator
+ @pre The iterator is initialized; i.e. `m_object != nullptr`.
+ */
+ reference value() const
+ {
+ return operator*();
+ }
+
+ private:
+ /// associated JSON instance
+ pointer m_object = nullptr;
+ /// the actual iterator of the associated instance
+ internal_iterator<typename std::remove_const<BasicJsonType>::type> m_it = {};
+};
+
+/// proxy class for the iterator_wrapper functions
+template <typename IteratorType> class iteration_proxy
+{
+ private:
+ /// helper class for iteration
+ class iteration_proxy_internal
+ {
+ private:
+ /// the iterator
+ IteratorType anchor;
+ /// an index for arrays (used to create key names)
+ size_t array_index = 0;
+
+ public:
+ explicit iteration_proxy_internal(IteratorType it) noexcept : anchor(it) {}
+
+ /// dereference operator (needed for range-based for)
+ iteration_proxy_internal& operator*()
+ {
+ return *this;
+ }
+
+ /// increment operator (needed for range-based for)
+ iteration_proxy_internal& operator++()
+ {
+ ++anchor;
+ ++array_index;
+
+ return *this;
+ }
+
+ /// inequality operator (needed for range-based for)
+ bool operator!=(const iteration_proxy_internal& o) const
+ {
+ return anchor != o.anchor;
+ }
+
+ /// return key of the iterator
+ std::string key() const
+ {
+ assert(anchor.m_object != nullptr);
+
+ switch (anchor.m_object->type())
+ {
+ // use integer array index as key
+ case value_t::array:
+ {
+ return std::to_string(array_index);
+ }
+
+ // use key from the object
+ case value_t::object:
+ {
+ return anchor.key();
+ }
+
+ // use an empty key for all primitive types
+ default:
+ {
+ return "";
+ }
+ }
+ }
+
+ /// return value of the iterator
+ typename IteratorType::reference value() const
+ {
+ return anchor.value();
+ }
+ };
+
+ /// the container to iterate
+ typename IteratorType::reference container;
+
+ public:
+ /// construct iteration proxy from a container
+ explicit iteration_proxy(typename IteratorType::reference cont)
+ : container(cont) {}
+
+ /// return iterator begin (needed for range-based for)
+ iteration_proxy_internal begin() noexcept
+ {
+ return iteration_proxy_internal(container.begin());
+ }
+
+ /// return iterator end (needed for range-based for)
+ iteration_proxy_internal end() noexcept
+ {
+ return iteration_proxy_internal(container.end());
+ }
+};
} // namespace detail
/// namespace to hold default `to_json` / `from_json` functions
@@ -4186,6 +4930,8 @@ class basic_json
template<detail::value_t> friend struct detail::external_constructor;
friend ::nlohmann::json_pointer;
friend ::nlohmann::detail::parser<basic_json>;
+ template <typename BasicJsonType>
+ friend class ::nlohmann::detail::iter_impl;
/// workaround type for MSVC
using basic_json_t = NLOHMANN_BASIC_JSON_TPL;
@@ -4194,11 +4940,16 @@ class basic_json
using parser = ::nlohmann::detail::parser<basic_json>;
using primitive_iterator_t = ::nlohmann::detail::primitive_iterator_t;
+ template <typename BasicJsonType>
+ using internal_iterator = ::nlohmann::detail::internal_iterator<BasicJsonType>;
+ template <typename BasicJsonType>
+ using iter_impl = ::nlohmann::detail::iter_impl<BasicJsonType>;
+ template <typename Iterator>
+ using iteration_proxy = ::nlohmann::detail::iteration_proxy<Iterator>;
public:
using value_t = detail::value_t;
// forward declarations
- template<typename U> class iter_impl;
template<typename Base> class json_reverse_iterator;
using json_pointer = ::nlohmann::json_pointer;
template<typename T, typename SFINAE>
@@ -7988,10 +8739,6 @@ class basic_json
return const_reverse_iterator(cbegin());
}
- private:
- // forward declaration
- template<typename IteratorType> class iteration_proxy;
-
public:
/*!
@brief wrapper to access iterator member functions in range-based for
@@ -10551,740 +11298,7 @@ class basic_json
/// the value of the current element
json_value m_value = {};
-
- private:
- /*!
- @brief an iterator value
-
- @note This structure could easily be a union, but MSVC currently does not
- allow unions members with complex constructors, see
- https://github.com/nlohmann/json/pull/105.
- */
- struct internal_iterator
- {
- /// iterator for JSON objects
- typename object_t::iterator object_iterator;
- /// iterator for JSON arrays
- typename array_t::iterator array_iterator;
- /// generic iterator for all other types
- primitive_iterator_t primitive_iterator;
-
- /// create an uninitialized internal_iterator
- internal_iterator() noexcept
- : object_iterator(), array_iterator(), primitive_iterator()
- {}
- };
-
- /// proxy class for the iterator_wrapper functions
- template<typename IteratorType>
- class iteration_proxy
- {
- private:
- /// helper class for iteration
- class iteration_proxy_internal
- {
- private:
- /// the iterator
- IteratorType anchor;
- /// an index for arrays (used to create key names)
- size_t array_index = 0;
-
- public:
- explicit iteration_proxy_internal(IteratorType it) noexcept
- : anchor(it)
- {}
-
- /// dereference operator (needed for range-based for)
- iteration_proxy_internal& operator*()
- {
- return *this;
- }
-
- /// increment operator (needed for range-based for)
- iteration_proxy_internal& operator++()
- {
- ++anchor;
- ++array_index;
-
- return *this;
- }
-
- /// inequality operator (needed for range-based for)
- bool operator!= (const iteration_proxy_internal& o) const
- {
- return anchor != o.anchor;
- }
-
- /// return key of the iterator
- typename basic_json::string_t key() const
- {
- assert(anchor.m_object != nullptr);
-
- switch (anchor.m_object->type())
- {
- // use integer array index as key
- case value_t::array:
- {
- return std::to_string(array_index);
- }
-
- // use key from the object
- case value_t::object:
- {
- return anchor.key();
- }
-
- // use an empty key for all primitive types
- default:
- {
- return "";
- }
- }
- }
-
- /// return value of the iterator
- typename IteratorType::reference value() const
- {
- return anchor.value();
- }
- };
-
- /// the container to iterate
- typename IteratorType::reference container;
-
- public:
- /// construct iteration proxy from a container
- explicit iteration_proxy(typename IteratorType::reference cont)
- : container(cont)
- {}
-
- /// return iterator begin (needed for range-based for)
- iteration_proxy_internal begin() noexcept
- {
- return iteration_proxy_internal(container.begin());
- }
-
- /// return iterator end (needed for range-based for)
- iteration_proxy_internal end() noexcept
- {
- return iteration_proxy_internal(container.end());
- }
- };
-
public:
- /*!
- @brief a template for a random access iterator for the @ref basic_json class
-
- This class implements a both iterators (iterator and const_iterator) for the
- @ref basic_json class.
-
- @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 default-constructed, it is *uninitialized* and most
- methods are undefined. **The library uses assertions to detect calls
- on uninitialized iterators.**
-
- @requirement The class satisfies the following concept requirements:
- - [RandomAccessIterator](http://en.cppreference.com/w/cpp/concept/RandomAccessIterator):
- The iterator that can be moved to point (forward and backward) to any
- element in constant time.
-
- @since version 1.0.0, simplified in version 2.0.9
- */
- template<typename U>
- class iter_impl : public std::iterator<std::random_access_iterator_tag, U>
- {
- /// allow basic_json to access private members
- friend class basic_json;
-
- // make sure U is basic_json or const basic_json
- static_assert(std::is_same<U, basic_json>::value
- or std::is_same<U, const basic_json>::value,
- "iter_impl only accepts (const) basic_json");
-
- public:
- /// the type of the values when the iterator is dereferenced
- using value_type = typename basic_json::value_type;
- /// a type to represent differences between iterators
- using difference_type = typename basic_json::difference_type;
- /// defines a pointer to the type iterated over (value_type)
- using pointer = typename std::conditional<std::is_const<U>::value,
- typename basic_json::const_pointer,
- typename basic_json::pointer>::type;
- /// defines a reference to the type iterated over (value_type)
- using reference = typename std::conditional<std::is_const<U>::value,
- typename basic_json::const_reference,
- typename basic_json::reference>::type;
- /// the category of the iterator
- using iterator_category = std::bidirectional_iterator_tag;
-
- /// default constructor
- iter_impl() = default;
-
- /*!
- @brief constructor for a given JSON instance
- @param[in] object pointer to a JSON object for this iterator
- @pre object != nullptr
- @post The iterator is initialized; i.e. `m_object != nullptr`.
- */
- explicit iter_impl(pointer object) noexcept
- : m_object(object)
- {
- assert(m_object != nullptr);
-
- switch (m_object->m_type)
- {
- case basic_json::value_t::object:
- {
- m_it.object_iterator = typename object_t::iterator();
- break;
- }
-
- case basic_json::value_t::array:
- {
- m_it.array_iterator = typename array_t::iterator();
- break;
- }
-
- default:
- {
- m_it.primitive_iterator = primitive_iterator_t();
- break;
- }
- }
- }
-
- /*!
- @note The conventional copy constructor and copy assignment are
- implicitly defined.
- Combined with the following converting constructor and assignment,
- they support: copy from iterator to iterator,
- copy from const iterator to const iterator,
- and conversion from iterator to const iterator.
- However conversion from const iterator to iterator is not defined.
- */
-
- /*!
- @brief converting constructor
- @param[in] other non-const iterator to copy from
- @note It is not checked whether @a other is initialized.
- */
- iter_impl(const iter_impl<basic_json>& other) noexcept
- : m_object(other.m_object), m_it(other.m_it)
- {}
-
- /*!
- @brief converting assignment
- @param[in,out] other non-const iterator to copy from
- @return const/non-const iterator
- @note It is not checked whether @a other is initialized.
- */
- iter_impl& operator=(const iter_impl<basic_json>& other) noexcept
- {
- m_object = other.m_object;
- m_it = other.m_it;
- return *this;
- }
-
- private:
- /*!
- @brief set the iterator to the first value
- @pre The iterator is initialized; i.e. `m_object != nullptr`.
- */
- void set_begin() noexcept
- {
- assert(m_object != nullptr);
-
- switch (m_object->m_type)
- {
- case basic_json::value_t::object:
- {
- m_it.object_iterator = m_object->m_value.object->begin();
- break;
- }
-
- case basic_json::value_t::array:
- {
- m_it.array_iterator = m_object->m_value.array->begin();
- break;
- }
-
- case basic_json::value_t::null:
- {
- // set to end so begin()==end() is true: null is empty
- m_it.primitive_iterator.set_end();
- break;
- }
-
- default:
- {
- m_it.primitive_iterator.set_begin();
- break;
- }
- }
- }
-
- /*!
- @brief set the iterator past the last value
- @pre The iterator is initialized; i.e. `m_object != nullptr`.
- */
- void set_end() noexcept
- {
- assert(m_object != nullptr);
-
- switch (m_object->m_type)
- {
- case basic_json::value_t::object:
- {
- m_it.object_iterator = m_object->m_value.object->end();
- break;
- }
-
- case basic_json::value_t::array:
- {
- m_it.array_iterator = m_object->m_value.array->end();
- break;
- }
-
- default:
- {
- m_it.primitive_iterator.set_end();
- break;
- }
- }
- }
-
- public:
- /*!
- @brief return a reference to the value pointed to by the iterator
- @pre The iterator is initialized; i.e. `m_object != nullptr`.
- */
- reference operator*() const
- {
- assert(m_object != nullptr);
-
- switch (m_object->m_type)
- {
- case basic_json::value_t::object:
- {
- assert(m_it.object_iterator != m_object->m_value.object->end());
- return m_it.object_iterator->second;
- }
-
- case basic_json::value_t::array:
- {
- assert(m_it.array_iterator != m_object->m_value.array->end());
- return *m_it.array_iterator;
- }
-
- case basic_json::value_t::null:
- {
- JSON_THROW(invalid_iterator::create(214, "cannot get value"));
- }
-
- default:
- {
- if (m_it.primitive_iterator.is_begin())
- {
- return *m_object;
- }
-
- JSON_THROW(invalid_iterator::create(214, "cannot get value"));
- }
- }
- }
-
- /*!
- @brief dereference the iterator
- @pre The iterator is initialized; i.e. `m_object != nullptr`.
- */
- pointer operator->() const
- {
- assert(m_object != nullptr);
-
- switch (m_object->m_type)
- {
- case basic_json::value_t::object:
- {
- assert(m_it.object_iterator != m_object->m_value.object->end());
- return &(m_it.object_iterator->second);
- }
-
- case basic_json::value_t::array:
- {
- assert(m_it.array_iterator != m_object->m_value.array->end());
- return &*m_it.array_iterator;
- }
-
- default:
- {
- if (m_it.primitive_iterator.is_begin())
- {
- return m_object;
- }
-
- JSON_THROW(invalid_iterator::create(214, "cannot get value"));
- }
- }
- }
-
- /*!
- @brief post-increment (it++)
- @pre The iterator is initialized; i.e. `m_object != nullptr`.
- */
- iter_impl operator++(int)
- {
- auto result = *this;
- ++(*this);
- return result;
- }
-
- /*!
- @brief pre-increment (++it)
- @pre The iterator is initialized; i.e. `m_object != nullptr`.
- */
- iter_impl& operator++()
- {
- assert(m_object != nullptr);
-
- switch (m_object->m_type)
- {
- case basic_json::value_t::object:
- {
- std::advance(m_it.object_iterator, 1);
- break;
- }
-
- case basic_json::value_t::array:
- {
- std::advance(m_it.array_iterator, 1);
- break;
- }
-
- default:
- {
- ++m_it.primitive_iterator;
- break;
- }
- }
-
- return *this;
- }
-
- /*!
- @brief post-decrement (it--)
- @pre The iterator is initialized; i.e. `m_object != nullptr`.
- */
- iter_impl operator--(int)
- {
- auto result = *this;
- --(*this);
- return result;
- }
-
- /*!
- @brief pre-decrement (--it)
- @pre The iterator is initialized; i.e. `m_object != nullptr`.
- */
- iter_impl& operator--()
- {
- assert(m_object != nullptr);
-
- switch (m_object->m_type)
- {
- case basic_json::value_t::object:
- {
- std::advance(m_it.object_iterator, -1);
- break;
- }
-
- case basic_json::value_t::array:
- {
- std::advance(m_it.array_iterator, -1);
- break;
- }
-
- default:
- {
- --m_it.primitive_iterator;
- break;
- }
- }
-
- return *this;
- }
-
- /*!
- @brief comparison: equal
- @pre The iterator is initialized; i.e. `m_object != nullptr`.
- */
- bool operator==(const iter_impl& other) const
- {
- // if objects are not the same, the comparison is undefined
- if (m_object != other.m_object)
- {
- JSON_THROW(invalid_iterator::create(212, "cannot compare iterators of different containers"));
- }
-
- assert(m_object != nullptr);
-
- switch (m_object->m_type)
- {
- case basic_json::value_t::object:
- {
- return (m_it.object_iterator == other.m_it.object_iterator);
- }
-
- case basic_json::value_t::array:
- {
- return (m_it.array_iterator == other.m_it.array_iterator);
- }
-
- default:
- {
- return (m_it.primitive_iterator == other.m_it.primitive_iterator);
- }
- }
- }
-
- /*!
- @brief comparison: not equal
- @pre The iterator is initialized; i.e. `m_object != nullptr`.
- */
- bool operator!=(const iter_impl& other) const
- {
- return not operator==(other);
- }
-
- /*!
- @brief comparison: smaller
- @pre The iterator is initialized; i.e. `m_object != nullptr`.
- */
- bool operator<(const iter_impl& other) const
- {
- // if objects are not the same, the comparison is undefined
- if (m_object != other.m_object)
- {
- JSON_THROW(invalid_iterator::create(212, "cannot compare iterators of different containers"));
- }
-
- assert(m_object != nullptr);
-
- switch (m_object->m_type)
- {
- case basic_json::value_t::object:
- {
- JSON_THROW(invalid_iterator::create(213, "cannot compare order of object iterators"));
- }
-
- case basic_json::value_t::array:
- {
- return (m_it.array_iterator < other.m_it.array_iterator);
- }
-
- default:
- {
- return (m_it.primitive_iterator < other.m_it.primitive_iterator);
- }
- }
- }
-
- /*!
- @brief comparison: less than or equal
- @pre The iterator is initialized; i.e. `m_object != nullptr`.
- */
- bool operator<=(const iter_impl& other) const
- {
- return not other.operator < (*this);
- }
-
- /*!
- @brief comparison: greater than
- @pre The iterator is initialized; i.e. `m_object != nullptr`.
- */
- bool operator>(const iter_impl& other) const
- {
- return not operator<=(other);
- }
-
- /*!
- @brief comparison: greater than or equal
- @pre The iterator is initialized; i.e. `m_object != nullptr`.
- */
- bool operator>=(const iter_impl& other) const
- {
- return not operator<(other);
- }
-
- /*!
- @brief add to iterator
- @pre The iterator is initialized; i.e. `m_object != nullptr`.
- */
- iter_impl& operator+=(difference_type i)
- {
- assert(m_object != nullptr);
-
- switch (m_object->m_type)
- {
- case basic_json::value_t::object:
- {
- JSON_THROW(invalid_iterator::create(209, "cannot use offsets with object iterators"));
- }
-
- case basic_json::value_t::array:
- {
- std::advance(m_it.array_iterator, i);
- break;
- }
-
- default:
- {
- m_it.primitive_iterator += i;
- break;
- }
- }
-
- return *this;
- }
-
- /*!
- @brief subtract from iterator
- @pre The iterator is initialized; i.e. `m_object != nullptr`.
- */
- iter_impl& operator-=(difference_type i)
- {
- return operator+=(-i);
- }
-
- /*!
- @brief add to iterator
- @pre The iterator is initialized; i.e. `m_object != nullptr`.
- */
- iter_impl operator+(difference_type i) const
- {
- auto result = *this;
- result += i;
- return result;
- }
-
- /*!
- @brief addition of distance and iterator
- @pre The iterator is initialized; i.e. `m_object != nullptr`.
- */
- friend iter_impl operator+(difference_type i, const iter_impl& it)
- {
- auto result = it;
- result += i;
- return result;
- }
-
- /*!
- @brief subtract from iterator
- @pre The iterator is initialized; i.e. `m_object != nullptr`.
- */
- iter_impl operator-(difference_type i) const
- {
- auto result = *this;
- result -= i;
- return result;
- }
-
- /*!
- @brief return difference
- @pre The iterator is initialized; i.e. `m_object != nullptr`.
- */
- difference_type operator-(const iter_impl& other) const
- {
- assert(m_object != nullptr);
-
- switch (m_object->m_type)
- {
- case basic_json::value_t::object:
- {
- JSON_THROW(invalid_iterator::create(209, "cannot use offsets with object iterators"));
- }
-
- case basic_json::value_t::array:
- {
- return m_it.array_iterator - other.m_it.array_iterator;
- }
-
- default:
- {
- return m_it.primitive_iterator - other.m_it.primitive_iterator;
- }
- }
- }
-
- /*!
- @brief access to successor
- @pre The iterator is initialized; i.e. `m_object != nullptr`.
- */
- reference operator[](difference_type n) const
- {
- assert(m_object != nullptr);
-
- switch (m_object->m_type)
- {
- case basic_json::value_t::object:
- {
- JSON_THROW(invalid_iterator::create(208, "cannot use operator[] for object iterators"));
- }
-
- case basic_json::value_t::array:
- {
- return *std::next(m_it.array_iterator, n);
- }
-
- case basic_json::value_t::null:
- {
- JSON_THROW(invalid_iterator::create(214, "cannot get value"));
- }
-
- default:
- {
- if (m_it.primitive_iterator.get_value() == -n)
- {
- return *m_object;
- }
-
- JSON_THROW(invalid_iterator::create(214, "cannot get value"));
- }
- }
- }
-
- /*!
- @brief return the key of an object iterator
- @pre The iterator is initialized; i.e. `m_object != nullptr`.
- */
- typename object_t::key_type key() const
- {
- assert(m_object != nullptr);
-
- if (m_object->is_object())
- {
- return m_it.object_iterator->first;
- }
-
- JSON_THROW(invalid_iterator::create(207, "cannot use key() for non-object iterators"));
- }
-
- /*!
- @brief return the value of an iterator
- @pre The iterator is initialized; i.e. `m_object != nullptr`.
- */
- reference value() const
- {
- return operator*();
- }
-
- private:
- /// associated JSON instance
- pointer m_object = nullptr;
- /// the actual iterator of the associated instance
- struct internal_iterator m_it = internal_iterator();
- };
-
/*!
@brief a template for a reverse iterator class