nlohmann::detail::iter_impl< BasicJsonType > Class Template Reference

a template for a bidirectional iterator for the basic_json class This class implements a both iterators (iterator and const_iterator) for the basic_json class. More...

#include <json.hpp>

Public Types
using	iterator_category = std::bidirectional_iterator_tag
using	value_type = typename BasicJsonType::value_type
	the type of the values when the iterator is dereferenced More...
using	difference_type = typename BasicJsonType::difference_type
	a type to represent differences between iterators More...
using	pointer = typename std::conditional< std::is_const< BasicJsonType >::value, typename BasicJsonType::const_pointer, typename BasicJsonType::pointer >::type
	defines a pointer to the type iterated over (value_type) More...
using	reference = typename std::conditional< std::is_const< BasicJsonType >::value, typename BasicJsonType::const_reference, typename BasicJsonType::reference >::type
	defines a reference to the type iterated over (value_type) More...

Public Member Functions
	iter_impl ()=default
	default constructor More...
	iter_impl (pointer object) noexcept
	constructor for a given JSON instance More...
	iter_impl (const iter_impl< const BasicJsonType > &other) noexcept
	const copy constructor More...
iter_impl &	operator= (const iter_impl< const BasicJsonType > &other) noexcept
	converting assignment More...
	iter_impl (const iter_impl< typename std::remove_const< BasicJsonType >::type > &other) noexcept
	converting constructor More...
iter_impl &	operator= (const iter_impl< typename std::remove_const< BasicJsonType >::type > &other) noexcept
	converting assignment More...
reference	operator* () const
	return a reference to the value pointed to by the iterator More...
pointer	operator-> () const
	dereference the iterator More...
iter_impl const	operator++ (int)
	post-increment (it++) More...
iter_impl &	operator++ ()
	pre-increment (++it) More...
iter_impl const	operator-- (int)
	post-decrement (it–) More...
iter_impl &	operator-- ()
	pre-decrement (–it) More...
bool	operator== (const iter_impl &other) const
	comparison: equal More...
bool	operator!= (const iter_impl &other) const
	comparison: not equal More...
bool	operator< (const iter_impl &other) const
	comparison: smaller More...
bool	operator<= (const iter_impl &other) const
	comparison: less than or equal More...
bool	operator> (const iter_impl &other) const
	comparison: greater than More...
bool	operator>= (const iter_impl &other) const
	comparison: greater than or equal More...
iter_impl &	operator+= (difference_type i)
	add to iterator More...
iter_impl &	operator-= (difference_type i)
	subtract from iterator More...
iter_impl	operator+ (difference_type i) const
	add to iterator More...
iter_impl	operator- (difference_type i) const
	subtract from iterator More...
difference_type	operator- (const iter_impl &other) const
	return difference More...
reference	operator[] (difference_type n) const
	access to successor More...
const object_t::key_type &	key () const
	return the key of an object iterator More...
reference	value () const
	return the value of an iterator More...

Private Types
using	object_t = typename BasicJsonType::object_t
using	array_t = typename BasicJsonType::array_t

Private Member Functions
void	set_begin () noexcept
	set the iterator to the first value More...
void	set_end () noexcept
	set the iterator past the last value More...

Private Attributes
friend	BasicJsonType
friend	iteration_proxy< iter_impl >
friend	iteration_proxy_value< iter_impl >
pointer	m_object = nullptr
	associated JSON instance More...
internal_iterator< typename std::remove_const < BasicJsonType >::type >	m_it {}
	the actual iterator of the associated instance More...

Friends
iter_impl	operator+ (difference_type i, const iter_impl &it)
	addition of distance and iterator More...

Detailed Description

template<typename BasicJsonType>
class nlohmann::detail::iter_impl< BasicJsonType >

a template for a bidirectional iterator for the basic_json class This class implements a both iterators (iterator and const_iterator) for the 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.** The class satisfies the following concept requirements:

• BidirectionalIterator: The iterator that can be moved can be moved in both directions (i.e. incremented and decremented).

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)

Definition at line 9346 of file json.hpp.

Member Typedef Documentation

template<typename BasicJsonType>

using nlohmann::detail::iter_impl< BasicJsonType >::array_t = typename BasicJsonType::array_t

private

Definition at line 9355 of file json.hpp.

template<typename BasicJsonType>

using nlohmann::detail::iter_impl< BasicJsonType >::difference_type = typename BasicJsonType::difference_type

a type to represent differences between iterators

Definition at line 9372 of file json.hpp.

template<typename BasicJsonType>

using nlohmann::detail::iter_impl< BasicJsonType >::iterator_category = std::bidirectional_iterator_tag

The std::iterator class template (used as a base class to provide typedefs) is deprecated in C++17. The C++ Standard has never required user-defined iterators to derive from std::iterator. A user-defined iterator should provide publicly accessible typedefs named iterator_category, value_type, difference_type, pointer, and reference. Note that value_type is required to be non-const, even for constant iterators.

Definition at line 9367 of file json.hpp.

template<typename BasicJsonType>

using nlohmann::detail::iter_impl< BasicJsonType >::object_t = typename BasicJsonType::object_t

private

Definition at line 9354 of file json.hpp.

template<typename BasicJsonType>

using nlohmann::detail::iter_impl< BasicJsonType >::pointer = typename std::conditional<std::is_const<BasicJsonType>::value, typename BasicJsonType::const_pointer, typename BasicJsonType::pointer>::type

defines a pointer to the type iterated over (value_type)

Definition at line 9376 of file json.hpp.

template<typename BasicJsonType>

using nlohmann::detail::iter_impl< BasicJsonType >::reference = typename std::conditional<std::is_const<BasicJsonType>::value, typename BasicJsonType::const_reference, typename BasicJsonType::reference>::type

defines a reference to the type iterated over (value_type)

Definition at line 9381 of file json.hpp.

template<typename BasicJsonType>

using nlohmann::detail::iter_impl< BasicJsonType >::value_type = typename BasicJsonType::value_type

the type of the values when the iterator is dereferenced

Definition at line 9370 of file json.hpp.

Constructor & Destructor Documentation

template<typename BasicJsonType>

iter_impl< typename std::conditional< std::is_const< BasicJsonType >::value, typename std::remove_const< BasicJsonType >::type, const BasicJsonType >::type > ( )

default

default constructor

allow basic_json to access private members

Definition at line 9349 of file json.hpp.

template<typename BasicJsonType>

nlohmann::detail::iter_impl< BasicJsonType >::iter_impl ( pointer  object )

inlineexplicitnoexcept

constructor for a given JSON instance

Parameters

[in]

object

pointer to a JSON object for this iterator

Precondition

object != nullptr

Postcondition

The iterator is initialized; i.e. m_object != nullptr.

Definition at line 9392 of file json.hpp.

                                                : 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;
            }
        }
    }

template<typename BasicJsonType>

nlohmann::detail::iter_impl< BasicJsonType >::iter_impl ( const iter_impl< const BasicJsonType > &  other )

inlinenoexcept

const copy constructor

Note

The conventional copy constructor and copy assignment are implicitly defined. Combined with the following converting constructor and assignment, they support: (1) copy from iterator to iterator, (2) copy from const iterator to const iterator, and (3) conversion from iterator to const iterator. However conversion from const iterator to iterator is not defined.

Parameters

[in]

other

const iterator to copy from

Note

This copy constructor had to be defined explicitly to circumvent a bug occurring on msvc v19.0 compiler (VS 2015) debug build. For more information refer to: https://github.com/nlohmann/json/issues/1608

Definition at line 9434 of file json.hpp.

        : m_object(other.m_object), m_it(other.m_it)
    {}

template<typename BasicJsonType>

nlohmann::detail::iter_impl< BasicJsonType >::iter_impl ( const iter_impl< typename std::remove_const< BasicJsonType >::type > &  other )

inlinenoexcept

converting constructor

Parameters

[in]

other

non-const iterator to copy from

Note

It is not checked whether other is initialized.

Definition at line 9456 of file json.hpp.

        : m_object(other.m_object), m_it(other.m_it)
    {}

Member Function Documentation

template<typename BasicJsonType>

const object_t::key_type& nlohmann::detail::iter_impl< BasicJsonType >::key ( ) const

inline

return the key of an object iterator

Precondition

The iterator is initialized; i.e. m_object != nullptr.

Definition at line 9916 of file json.hpp.

    {
        assert(m_object != nullptr);

        if (JSON_HEDLEY_LIKELY(m_object->is_object()))
        {
            return m_it.object_iterator->first;
        }

        JSON_THROW(invalid_iterator::create(207, "cannot use key() for non-object iterators"));
    }

template<typename BasicJsonType>

bool nlohmann::detail::iter_impl< BasicJsonType >::operator!= ( const iter_impl< BasicJsonType > &  other ) const

inline

comparison: not equal

Precondition

The iterator is initialized; i.e. m_object != nullptr.

Definition at line 9730 of file json.hpp.

    {
        return not operator==(other);
    }

template<typename BasicJsonType>

reference nlohmann::detail::iter_impl< BasicJsonType >::operator* ( ) const

inline

return a reference to the value pointed to by the iterator

Precondition

The iterator is initialized; i.e. m_object != nullptr.

Definition at line 9546 of file json.hpp.

    {
        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 (JSON_HEDLEY_LIKELY(m_it.primitive_iterator.is_begin()))
                {
                    return *m_object;
                }

                JSON_THROW(invalid_iterator::create(214, "cannot get value"));
            }
        }
    }

template<typename BasicJsonType>

iter_impl nlohmann::detail::iter_impl< BasicJsonType >::operator+ ( difference_type  i ) const

inline

add to iterator

Precondition

The iterator is initialized; i.e. m_object != nullptr.

Definition at line 9831 of file json.hpp.

    {
        auto result = *this;
        result += i;
        return result;
    }

template<typename BasicJsonType>

iter_impl const nlohmann::detail::iter_impl< BasicJsonType >::operator++ ( int  )

inline

post-increment (it++)

Precondition

The iterator is initialized; i.e. m_object != nullptr.

Definition at line 9617 of file json.hpp.

    {
        auto result = *this;
        ++(*this);
        return result;
    }

template<typename BasicJsonType>

iter_impl& nlohmann::detail::iter_impl< BasicJsonType >::operator++ ( )

inline

pre-increment (++it)

Precondition

The iterator is initialized; i.e. m_object != nullptr.

Definition at line 9628 of file json.hpp.

    {
        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;
    }

template<typename BasicJsonType>

iter_impl& nlohmann::detail::iter_impl< BasicJsonType >::operator+= ( difference_type  i )

inline

add to iterator

Precondition

The iterator is initialized; i.e. m_object != nullptr.

Definition at line 9793 of file json.hpp.

    {
        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;
    }

template<typename BasicJsonType>

iter_impl nlohmann::detail::iter_impl< BasicJsonType >::operator- ( difference_type  i ) const

inline

subtract from iterator

Precondition

The iterator is initialized; i.e. m_object != nullptr.

Definition at line 9853 of file json.hpp.

    {
        auto result = *this;
        result -= i;
        return result;
    }

template<typename BasicJsonType>

difference_type nlohmann::detail::iter_impl< BasicJsonType >::operator- ( const iter_impl< BasicJsonType > &  other ) const

inline

return difference

Precondition

The iterator is initialized; i.e. m_object != nullptr.

Definition at line 9864 of file json.hpp.

    {
        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;
        }
    }

template<typename BasicJsonType>

iter_impl const nlohmann::detail::iter_impl< BasicJsonType >::operator-- ( int  )

inline

post-decrement (it–)

Precondition

The iterator is initialized; i.e. m_object != nullptr.

Definition at line 9660 of file json.hpp.

    {
        auto result = *this;
        --(*this);
        return result;
    }

template<typename BasicJsonType>

iter_impl& nlohmann::detail::iter_impl< BasicJsonType >::operator-- ( )

inline

pre-decrement (–it)

Precondition

The iterator is initialized; i.e. m_object != nullptr.

Definition at line 9671 of file json.hpp.

    {
        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;
    }

template<typename BasicJsonType>

iter_impl& nlohmann::detail::iter_impl< BasicJsonType >::operator-= ( difference_type  i )

inline

subtract from iterator

Precondition

The iterator is initialized; i.e. m_object != nullptr.

Definition at line 9822 of file json.hpp.

    {
        return operator+=(-i);
    }

template<typename BasicJsonType>

pointer nlohmann::detail::iter_impl< BasicJsonType >::operator-> ( ) const

inline

dereference the iterator

Precondition

The iterator is initialized; i.e. m_object != nullptr.

Definition at line 9583 of file json.hpp.

    {
        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 (JSON_HEDLEY_LIKELY(m_it.primitive_iterator.is_begin()))
                {
                    return m_object;
                }

                JSON_THROW(invalid_iterator::create(214, "cannot get value"));
            }
        }
    }

template<typename BasicJsonType>

bool nlohmann::detail::iter_impl< BasicJsonType >::operator< ( const iter_impl< BasicJsonType > &  other ) const

inline

comparison: smaller

Precondition

The iterator is initialized; i.e. m_object != nullptr.

Definition at line 9739 of file json.hpp.

    {
        // if objects are not the same, the comparison is undefined
        if (JSON_HEDLEY_UNLIKELY(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);
        }
    }

template<typename BasicJsonType>

bool nlohmann::detail::iter_impl< BasicJsonType >::operator<= ( const iter_impl< BasicJsonType > &  other ) const

inline

comparison: less than or equal

Precondition

The iterator is initialized; i.e. m_object != nullptr.

Definition at line 9766 of file json.hpp.

    {
        return not other.operator < (*this);
    }

template<typename BasicJsonType>

iter_impl& nlohmann::detail::iter_impl< BasicJsonType >::operator= ( const iter_impl< const BasicJsonType > &  other )

inlinenoexcept

converting assignment

Parameters

[in]

other

const iterator to copy from

Returns

const/non-const iterator

Note

It is not checked whether other is initialized.

Definition at line 9444 of file json.hpp.

    {
        m_object = other.m_object;
        m_it = other.m_it;
        return *this;
    }

template<typename BasicJsonType>

iter_impl& nlohmann::detail::iter_impl< BasicJsonType >::operator= ( const iter_impl< typename std::remove_const< BasicJsonType >::type > &  other )

inlinenoexcept

converting assignment

Parameters

[in]

other

non-const iterator to copy from

Returns

const/non-const iterator

Note

It is not checked whether other is initialized.

Definition at line 9466 of file json.hpp.

    {
        m_object = other.m_object;
        m_it = other.m_it;
        return *this;
    }

template<typename BasicJsonType>

bool nlohmann::detail::iter_impl< BasicJsonType >::operator== ( const iter_impl< BasicJsonType > &  other ) const

inline

comparison: equal

Precondition

The iterator is initialized; i.e. m_object != nullptr.

Definition at line 9703 of file json.hpp.

    {
        // if objects are not the same, the comparison is undefined
        if (JSON_HEDLEY_UNLIKELY(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);
        }
    }

template<typename BasicJsonType>

bool nlohmann::detail::iter_impl< BasicJsonType >::operator> ( const iter_impl< BasicJsonType > &  other ) const

inline

comparison: greater than

Precondition

The iterator is initialized; i.e. m_object != nullptr.

Definition at line 9775 of file json.hpp.

    {
        return not operator<=(other);
    }

template<typename BasicJsonType>

bool nlohmann::detail::iter_impl< BasicJsonType >::operator>= ( const iter_impl< BasicJsonType > &  other ) const

inline

comparison: greater than or equal

Precondition

The iterator is initialized; i.e. m_object != nullptr.

Definition at line 9784 of file json.hpp.

    {
        return not operator<(other);
    }

template<typename BasicJsonType>

reference nlohmann::detail::iter_impl< BasicJsonType >::operator[] ( difference_type  n ) const

inline

access to successor

Precondition

The iterator is initialized; i.e. m_object != nullptr.

Definition at line 9885 of file json.hpp.

    {
        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 (JSON_HEDLEY_LIKELY(m_it.primitive_iterator.get_value() == -n))
                {
                    return *m_object;
                }

                JSON_THROW(invalid_iterator::create(214, "cannot get value"));
            }
        }
    }

template<typename BasicJsonType>

void nlohmann::detail::iter_impl< BasicJsonType >::set_begin ( )

inlineprivatenoexcept

set the iterator to the first value

Precondition

The iterator is initialized; i.e. m_object != nullptr.

Definition at line 9478 of file json.hpp.

    {
        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;
            }
        }
    }

template<typename BasicJsonType>

void nlohmann::detail::iter_impl< BasicJsonType >::set_end ( )

inlineprivatenoexcept

set the iterator past the last value

Precondition

The iterator is initialized; i.e. m_object != nullptr.

Definition at line 9515 of file json.hpp.

    {
        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;
            }
        }
    }

template<typename BasicJsonType>

reference nlohmann::detail::iter_impl< BasicJsonType >::value ( ) const

inline

return the value of an iterator

Precondition

The iterator is initialized; i.e. m_object != nullptr.

Definition at line 9932 of file json.hpp.

    {
        return operator*();
    }

Friends And Related Function Documentation

template<typename BasicJsonType>

iter_impl operator+ ( difference_type  i, const iter_impl< BasicJsonType > &  it  )

friend

addition of distance and iterator

Precondition

The iterator is initialized; i.e. m_object != nullptr.

Definition at line 9842 of file json.hpp.

    {
        auto result = it;
        result += i;
        return result;
    }

Member Data Documentation

template<typename BasicJsonType>

friend nlohmann::detail::iter_impl< BasicJsonType >::BasicJsonType

private

Definition at line 9350 of file json.hpp.

template<typename BasicJsonType>

friend nlohmann::detail::iter_impl< BasicJsonType >::iteration_proxy< iter_impl >

private

Definition at line 9351 of file json.hpp.

template<typename BasicJsonType>

friend nlohmann::detail::iter_impl< BasicJsonType >::iteration_proxy_value< iter_impl >

private

Definition at line 9352 of file json.hpp.

template<typename BasicJsonType>

internal_iterator<typename std::remove_const<BasicJsonType>::type> nlohmann::detail::iter_impl< BasicJsonType >::m_it {}

private

the actual iterator of the associated instance

Definition at line 9941 of file json.hpp.

template<typename BasicJsonType>

pointer nlohmann::detail::iter_impl< BasicJsonType >::m_object = nullptr

private

associated JSON instance

Definition at line 9939 of file json.hpp.

---

The documentation for this class was generated from the following file:

• json.hpp