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QJsonObject::iterator Class Reference

\inmodule QtCore\reentrant More...

#include <qjsonobject.h>

Collaboration diagram for QJsonObject::iterator:

Public Types

typedef std::random_access_iterator_tag iterator_category
 A synonym for {std::random_access_iterator_tag} indicating this iterator is a random-access iterator.
typedef qsizetype difference_type
typedef QJsonValue value_type
typedef QJsonValueRef reference
typedef QJsonValueRef * pointer

Public Member Functions

 iterator ()
 Constructs an uninitialized iterator.
 iterator (QJsonObject *obj, qsizetype index)
constexpr iterator (const iterator &other)=default
iterator & operator= (const iterator &other)
QString key () const
 Returns the current item's key.
QAnyStringView keyView () const
QJsonValueRef value () const
 Returns a modifiable reference to the current item's value.
QJsonValueRef operator* () const
 Returns a modifiable reference to the current item's value.
const QJsonValueConstRef * operator-> () const
 Returns a pointer to a constant reference to the current item.
QJsonValueRef * operator-> ()
 Returns a pointer to a modifiable reference to the current item.
QJsonValueRef operator[] (qsizetype j) const
 Returns a modifiable reference to the item at offset j from the item pointed to by this iterator (the item at position {*this + j}).
iterator & operator++ ()
 The prefix {++} operator, {++i}, advances the iterator to the next item in the object and returns an iterator to the new current item.
iterator operator++ (int)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.The postfix {++} operator, {i++}, advances the iterator to the next item in the object and returns an iterator to the previously current item.
iterator & operator-- ()
 The prefix {–} operator, {–i}, makes the preceding item current and returns an iterator pointing to the new current item.
iterator operator-- (int)
 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.The postfix {–} operator, {i–}, makes the preceding item current and returns an iterator pointing to the previously current item.
iterator operator+ (qsizetype j) const
 Returns an iterator to the item at j positions forward from this iterator.
iterator operator- (qsizetype j) const
 Returns an iterator to the item at j positions backward from this iterator.
iterator & operator+= (qsizetype j)
 Advances the iterator by j items.
iterator & operator-= (qsizetype j)
 Makes the iterator go back by j items.
qsizetype operator- (iterator j) const
 Returns the number of items between the item pointed to by other and the item pointed to by this iterator.

Friends

class const_iterator
class QJsonObject
bool comparesEqual (const iterator &lhs, const iterator &rhs) noexcept
Qt::strong_ordering compareThreeWay (const iterator &lhs, const iterator &rhs)
bool comparesEqual (const iterator &lhs, const const_iterator &rhs) noexcept
Qt::strong_ordering compareThreeWay (const iterator &lhs, const const_iterator &rhs)

Detailed Description

\inmodule QtCore

\reentrant

Since
5.0

The QJsonObject::iterator class provides an STL-style non-const iterator for QJsonObject.

\compares strong \compareswith strong QJsonObject::const_iterator \endcompareswith

QJsonObject::iterator allows you to iterate over a QJsonObject and to modify the value (but not the key) stored under a particular key. If you want to iterate over a const QJsonObject, you should use QJsonObject::const_iterator. It is generally good practice to use QJsonObject::const_iterator on a non-const QJsonObject as well, unless you need to change the QJsonObject through the iterator. Const iterators are slightly faster, and improve code readability.

The default QJsonObject::iterator constructor creates an uninitialized iterator. You must initialize it using a QJsonObject function like QJsonObject::begin(), QJsonObject::end(), or QJsonObject::find() before you can start iterating.

Multiple iterators can be used on the same object. Existing iterators will however become dangling once the object gets modified.

See also
QJsonObject::const_iterator, {JSON Support in Qt}, {Saving and Loading a Game}

Definition at line 95 of file qjsonobject.h.

Member Typedef Documentation

◆ difference_type

typedef qsizetype QJsonObject::iterator::difference_type

Definition at line 103 of file qjsonobject.h.

◆ iterator_category

typedef std::random_access_iterator_tag QJsonObject::iterator::iterator_category

A synonym for {std::random_access_iterator_tag} indicating this iterator is a random-access iterator.

Note
In Qt versions before 5.6, this was set by mistake to {std::bidirectional_iterator_tag}.

Definition at line 102 of file qjsonobject.h.

◆ pointer

typedef QJsonValueRef* QJsonObject::iterator::pointer

Definition at line 106 of file qjsonobject.h.

◆ reference

typedef QJsonValueRef QJsonObject::iterator::reference

Definition at line 105 of file qjsonobject.h.

◆ value_type

typedef QJsonValue QJsonObject::iterator::value_type

Definition at line 104 of file qjsonobject.h.

Constructor & Destructor Documentation

◆ iterator() [1/3]

QJsonObject::iterator::iterator ( )
inline

Constructs an uninitialized iterator.

Functions like key(), value(), and operator++() must not be called on an uninitialized iterator. Use operator=() to assign a value to it before using it.

See also
QJsonObject::begin(), QJsonObject::end()

Definition at line 108 of file qjsonobject.h.

◆ iterator() [2/3]

QJsonObject::iterator::iterator ( QJsonObject * obj,
qsizetype index )
inline

Definition at line 109 of file qjsonobject.h.

◆ iterator() [3/3]

QJsonObject::iterator::iterator ( const iterator & other)
constexprdefault

Member Function Documentation

◆ key()

QString QJsonObject::iterator::key ( ) const
inline

Returns the current item's key.

There is no direct way of changing an item's key through an iterator, although it can be done by calling QJsonObject::erase() followed by QJsonObject::insert().

See also
value(), keyView()

Definition at line 118 of file qjsonobject.h.

◆ keyView()

QAnyStringView QJsonObject::iterator::keyView ( ) const
inline
Since
6.10

Returns the current item's key as a QAnyStringView. This function does not allocate memory.

Since QJsonObject stores keys in US-ASCII, UTF-8 or UTF-16, the returned QAnyStringView may be in any of these encodings.

There is no direct way of changing an item's key through an iterator, although it can be done by calling QJsonObject::erase() followed by QJsonObject::insert().

See also
key(), value()

Definition at line 119 of file qjsonobject.h.

◆ operator*()

QJsonValueRef QJsonObject::iterator::operator* ( ) const
inline

Returns a modifiable reference to the current item's value.

Same as value().

The return value is of type QJsonValueRef, a helper class for QJsonArray and QJsonObject. When you get an object of type QJsonValueRef, you can use it as if it were a reference to a QJsonValue. If you assign to it, the assignment will apply to the element in the QJsonArray or QJsonObject from which you got the reference.

See also
key(), keyView()

Definition at line 121 of file qjsonobject.h.

◆ operator+()

iterator QJsonObject::iterator::operator+ ( qsizetype j) const
inline

Returns an iterator to the item at j positions forward from this iterator.

If j is negative, the iterator goes backward.

See also
operator-()

Definition at line 140 of file qjsonobject.h.

◆ operator++() [1/2]

iterator & QJsonObject::iterator::operator++ ( )
inline

The prefix {++} operator, {++i}, advances the iterator to the next item in the object and returns an iterator to the new current item.

Calling this function on QJsonObject::end() leads to undefined results.

See also
operator--()

Definition at line 136 of file qjsonobject.h.

◆ operator++() [2/2]

iterator QJsonObject::iterator::operator++ ( int )
inline

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.The postfix {++} operator, {i++}, advances the iterator to the next item in the object and returns an iterator to the previously current item.

Definition at line 137 of file qjsonobject.h.

◆ operator+=()

iterator & QJsonObject::iterator::operator+= ( qsizetype j)
inline

Advances the iterator by j items.

If j is negative, the iterator goes backward.

See also
operator-=(), operator+()

Definition at line 142 of file qjsonobject.h.

◆ operator-() [1/2]

qsizetype QJsonObject::iterator::operator- ( iterator j) const
inline

Returns the number of items between the item pointed to by other and the item pointed to by this iterator.

Definition at line 144 of file qjsonobject.h.

◆ operator-() [2/2]

iterator QJsonObject::iterator::operator- ( qsizetype j) const
inline

Returns an iterator to the item at j positions backward from this iterator.

If j is negative, the iterator goes forward.

See also
operator+()

Definition at line 141 of file qjsonobject.h.

◆ operator--() [1/2]

iterator & QJsonObject::iterator::operator-- ( )
inline

The prefix {–} operator, {–i}, makes the preceding item current and returns an iterator pointing to the new current item.

Calling this function on QJsonObject::begin() leads to undefined results.

See also
operator++()

Definition at line 138 of file qjsonobject.h.

◆ operator--() [2/2]

iterator QJsonObject::iterator::operator-- ( int )
inline

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.The postfix {–} operator, {i–}, makes the preceding item current and returns an iterator pointing to the previously current item.

Definition at line 139 of file qjsonobject.h.

◆ operator-=()

iterator & QJsonObject::iterator::operator-= ( qsizetype j)
inline

Makes the iterator go back by j items.

If j is negative, the iterator goes forward.

See also
operator+=(), operator-()

Definition at line 143 of file qjsonobject.h.

◆ operator->() [1/2]

QJsonValueRef * QJsonObject::iterator::operator-> ( )
inline

Returns a pointer to a modifiable reference to the current item.

Definition at line 123 of file qjsonobject.h.

◆ operator->() [2/2]

const QJsonValueConstRef * QJsonObject::iterator::operator-> ( ) const
inline

Returns a pointer to a constant reference to the current item.

Definition at line 122 of file qjsonobject.h.

◆ operator=()

iterator & QJsonObject::iterator::operator= ( const iterator & other)
inline

Definition at line 112 of file qjsonobject.h.

◆ operator[]()

QJsonValueRef QJsonObject::iterator::operator[] ( qsizetype j) const
inline

Returns a modifiable reference to the item at offset j from the item pointed to by this iterator (the item at position {*this + j}).

This function is provided to make QJsonObject iterators behave like C++ pointers.

The return value is of type QJsonValueRef, a helper class for QJsonArray and QJsonObject. When you get an object of type QJsonValueRef, you can use it as if it were a reference to a QJsonValue. If you assign to it, the assignment will apply to the element in the QJsonArray or QJsonObject from which you got the reference.

See also
operator+()

Definition at line 124 of file qjsonobject.h.

◆ value()

QJsonValueRef QJsonObject::iterator::value ( ) const
inline

Returns a modifiable reference to the current item's value.

You can change the value of an item by using value() on the left side of an assignment.

The return value is of type QJsonValueRef, a helper class for QJsonArray and QJsonObject. When you get an object of type QJsonValueRef, you can use it as if it were a reference to a QJsonValue. If you assign to it, the assignment will apply to the element in the QJsonArray or QJsonObject from which you got the reference.

See also
key(), keyView(), operator*()

Definition at line 120 of file qjsonobject.h.

◆ comparesEqual [1/2]

bool comparesEqual ( const iterator & lhs,
const const_iterator & rhs )
friend

Definition at line 194 of file qjsonobject.h.

◆ comparesEqual [2/2]

bool comparesEqual ( const iterator & lhs,
const iterator & rhs )
friend

Definition at line 183 of file qjsonobject.h.

◆ compareThreeWay [1/2]

Qt::strong_ordering compareThreeWay ( const iterator & lhs,
const const_iterator & rhs )
friend

Definition at line 198 of file qjsonobject.h.

◆ compareThreeWay [2/2]

Qt::strong_ordering compareThreeWay ( const iterator & lhs,
const iterator & rhs )
friend

Definition at line 187 of file qjsonobject.h.

◆ const_iterator

friend class const_iterator
friend

Definition at line 97 of file qjsonobject.h.

◆ QJsonObject

friend class QJsonObject
friend

Definition at line 98 of file qjsonobject.h.

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