STL style iterator for QFlatMap. More...

Public Typedefs
using	iterator_category = std::bidirectional_iterator_tag

Public Methods
	iterator () = default

const Key &	key () const

bool	operator!= (iterator other) const

Val &	operator* () const

iterator	operator+ (size_type n) const

iterator &	operator++ ()

iterator	operator++ (int)

iterator &	operator+= (size_type n)

iterator	operator- (size_type n) const

iterator &	operator-- ()

iterator	operator-- (int)

iterator &	operator-= (size_type n)

Val *	operator-> () const

bool	operator== (iterator other) const

std::pair< Key, Val > &	pair () const

Val &	value () const

Friends
class	QFlatMap< Key, Val, C >

Detailed Description

template<typename Key, typename Val, typename C>
class QFlatMap< Key, Val, C >::iterator

The QFlatMap::iterator class provides an STL style iterator for QFlatMap. QFlatMap features both STL style iterators and Java style iterators.

QFlatMap::const_iterator allows you to iterate over a QFlatMap. If you want to modify the QFlatMap as you iterate over it use QFlatMap::iterator instead.

After construction you must initialize the iterator using a method like QFlatMap::begin(), QFlatMap::end(), or QFlatMap::find() before you can start iterating.

The following example prints all of the (key, value) pairs stored in the flat map.

QFlatMap<QString, int> flatMap;
 
flatMap.insert("January",  1);
flatMap.insert("February", 2);
...
flatMap.insert("December", 12);
 
for (auto iter = flatMap.constBegin(); iter != flatMap.constEnd(); ++iter) {
    cout << iter.key() << ": " << iter.value() << endl;
}

The following is an example which increments every value stored in the QFlatMap by 2:

QFlatMap<QString, int>::iterator iter;
 
for (iter = flatMap.begin(); iter != flatMap.end(); ++iter) {
   iter.value() += 2;
}

Here is an example which removes all the items whose key is a string that starts with an underscore character.

QFlatMap<QString, int>::iterator iter = flatMap.begin();
 
while (iter != flatMap.end()) {
    if (iter.key().startsWith("_")) {
        iter = flatMap.erase(iter);
    } else {
        ++iter;
    }
}

The call to QFlatMap::erase() removes the item pointed to by the iterator in the flat map and returns an iterator to the next item. Here is another way of removing an item while iterating:

QFlatMap<QString, int>::iterator iter = flatMap.begin();
 
while (iter != flatMap.end()) {
    QFlatMap<QString, int>::iterator prev = iter;
    ++iter;
 
    if (prev.key().startsWith("_")) {
       flatMap.erase(prev);
    }
}

It might be tempting to write code like the following, however it is invalid. This code will potentially crash in ++iter, because iter is invalid after the call to erase().

// INCORRECT
while (iter != flatMap.end()) {
    if (iter.key().startsWith("_")) {
        flatMap.erase(iter);
    }
 
    ++iter;
}

See also: QFlatMap::const_iterator

Member Typedef Documentation

template<typename Key , typename Val , typename C >

QFlatMap< Key, Val, C >::iterator::iterator_category

A synonym for std::bidirectional_iterator_tag indicating this iterator is a bidirectional iterator.

Constructor & Destructor Documentation

template<typename Key , typename Val , typename C >

QFlatMap< Key, Val, C >::iterator::iterator ( )

default

Constructs an uninitialized iterator.

Methods 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: QFlatMap::begin(), QFlatMap::end()

Method Documentation

template<typename Key , typename Val , typename C >

const Key & QFlatMap< Key, Val, C >::iterator::key ( ) const

inline

Returns the current item's key as a const reference.

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

See also: value()

template<typename Key , typename Val , typename C >

bool QFlatMap< Key, Val, C >::iterator::operator!= ( iterator other ) const

inline

Returns true if other points to a different item than this iterator, otherwise it returns false.

See also: operator==()

template<typename Key , typename Val , typename C >

Val & QFlatMap< Key, Val, C >::iterator::operator* ( ) const

inline

Equivalent to calling value().

See also: key()

template<typename Key , typename Val , typename C >

iterator QFlatMap< Key, Val, C >::iterator::operator+ ( size_type n ) const

inline

Returns an iterator to the item at n positions forward from this iterator. If n is negative the iterator goes backward.

This operation can be slow for large values of n.

See also: operator-()

template<typename Key , typename Val , typename C >

iterator & QFlatMap< Key, Val, C >::iterator::operator++ ( )

inline

The prefix ++ operator (++i) advances the iterator to the next item in the flat map and returns an iterator to the new current item.

Calling this method on QFlatMap::end() leads to undefined behavior.

See also: operator--()

template<typename Key , typename Val , typename C >

iterator QFlatMap< Key, Val, C >::iterator::operator++ ( int )

inline

The postfix ++ operator (i++) advances the iterator to the next item in the flat map and returns an iterator to the previously current item.

template<typename Key , typename Val , typename C >

iterator & QFlatMap< Key, Val, C >::iterator::operator+= ( size_type n )

inline

Advances the iterator by n items. If n is negative the iterator goes backward.

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

template<typename Key , typename Val , typename C >

iterator QFlatMap< Key, Val, C >::iterator::operator- ( size_type n ) const

inline

Returns an iterator to the item at n positions backward from this iterator. If n is negative the iterator goes forward.

This operation can be slow for large values of n.

See also: operator+()

template<typename Key , typename Val , typename C >

iterator & QFlatMap< Key, Val, C >::iterator::operator-- ( )

inline

The prefix – operator (–i) makes the preceding item current and returns an iterator pointing to the new current item.

Calling this method on QFlatMap::begin() leads to undefined behavior.

See also: operator++()

template<typename Key , typename Val , typename C >

iterator QFlatMap< Key, Val, C >::iterator::operator-- ( int )

inline

The postfix – operator (i–) makes the preceding item current and returns an iterator pointing to the previously current item.

template<typename Key , typename Val , typename C >

iterator & QFlatMap< Key, Val, C >::iterator::operator-= ( size_type n )

inline

Makes the iterator go back by n items. If n is negative the iterator goes forward.

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

template<typename Key , typename Val , typename C >

Val * QFlatMap< Key, Val, C >::iterator::operator-> ( ) const

inline

Returns a pointer to the current item's value.

See also: value()

template<typename Key , typename Val , typename C >

bool QFlatMap< Key, Val, C >::iterator::operator== ( iterator other ) const

inline

Returns true if other points to the same item as this iterator, otherwise it returns false.

See also: operator!=()

template<typename Key , typename Val , typename C >

std::pair< Key, Val > & QFlatMap< Key, Val, C >::iterator::pair ( ) const

inline

Returns a pair consisting of the key and the value.

template<typename Key , typename Val , typename C >

Val & QFlatMap< Key, Val, C >::iterator::value ( ) const

inline

Returns a reference to the value of the current item. You can change the value of an item by using value() on the left side of an assignment.

if (i.key() == "Hello") {
   i.value() = "Bonjour";
}

See also: key(), operator*()

Public Typedefs

Public Methods

Friends

Detailed Description

template<typename Key, typename Val, typename C> class QFlatMap< Key, Val, C >::iterator

Member Typedef Documentation

Constructor & Destructor Documentation

Method Documentation

template<typename Key, typename Val, typename C>
class QFlatMap< Key, Val, C >::iterator