Struct qt_core::q_map_of_int_q_variant::Iterator

#[repr(C)]
pub struct Iterator { /* private fields */ }

The QMap::iterator class provides an STL-style non-const iterator for QMap and QMultiMap.

C++ class: QMap<int, QVariant>::iterator.

C++ documentation:

The QMap::iterator class provides an STL-style non-const iterator for QMap and QMultiMap.

QMap features both STL-style iterators and Java-style iterators. The STL-style iterators are more low-level and more cumbersome to use; on the other hand, they are slightly faster and, for developers who already know STL, have the advantage of familiarity.

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

The default QMap::iterator constructor creates an uninitialized iterator. You must initialize it using a QMap function like QMap::begin(), QMap::end(), or QMap::find() before you can start iterating. Here's a typical loop that prints all the (key, value) pairs stored in a map:

QMap<QString, int> map;
map.insert(“January”, 1);
map.insert(“February”, 2);
...
map.insert(“December”, 12);
QMap<QString, int>::iterator i;
for (i = map.begin(); i != map.end(); ++i)
      cout << i.key() << “: “ << i.value() << endl;

Unlike QHash, which stores its items in an arbitrary order, QMap stores its items ordered by key. Items that share the same key (because they were inserted using QMap::insertMulti(), or due to a unite()) will appear consecutively, from the most recently to the least recently inserted value.

Let's see a few examples of things we can do with a QMap::iterator that we cannot do with a QMap::const_iterator. Here's an example that increments every value stored in the QMap by 2:

QMap<QString, int>::iterator i;
for (i = map.begin(); i != map.end(); ++i)
      i.value() += 2;

Here's an example that removes all the items whose key is a string that starts with an underscore character:

QMap<QString, int>::iterator i = map.begin();
while (i != map.end()) {
      if (i.key().startsWith(‘_’))
          i = map.erase(i);
      else
          ++i;
}

The call to QMap::erase() removes the item pointed to by the iterator from the map, and returns an iterator to the next item. Here's another way of removing an item while iterating:

QMap<QString, int>::iterator i = map.begin();
while (i != map.end()) {
      QMap<QString, int>::iterator prev = i;
      ++i;
      if (prev.key().startsWith(‘_’))
          map.erase(prev);
}

It might be tempting to write code like this:

// WRONG
while (i != map.end()) {
      if (i.key().startsWith(‘_’))
          map.erase(i);
      ++i;
}

However, this will potentially crash in ++i, because i is a dangling iterator after the call to erase().

Multiple iterators can be used on the same map. If you add items to the map, existing iterators will remain valid. If you remove items from the map, iterators that point to the removed items will become dangling iterators.

Warning: Iterators on implicitly shared containers do not work exactly like STL-iterators. You should avoid copying a container while iterators are active on that container. For more information, read Implicit sharing iterator problem.

Implementations

impl Iterator

pub unsafe fn add_assign(&self, j: c_int) -> Ref<Iterator>

Advances the iterator by j items. (If j is negative, the iterator goes backward.)

Calls C++ function: QMap<int, QVariant>::iterator& QMap<int, QVariant>::iterator::operator+=(int j).

C++ documentation:

Advances the iterator by j items. (If j is negative, the iterator goes backward.)

See also operator-=() and operator+().

pub unsafe fn copy_from( &self, other: impl CastInto<Ref<Iterator>> ) -> Ref<Iterator>

The QMap::iterator class provides an STL-style non-const iterator for QMap and QMultiMap.

Calls C++ function: QMap<int, QVariant>::iterator& QMap<int, QVariant>::iterator::operator=(const QMap<int, QVariant>::iterator& other).

C++ documentation:

The QMap::iterator class provides an STL-style non-const iterator for QMap and QMultiMap.

QMap features both STL-style iterators and Java-style iterators. The STL-style iterators are more low-level and more cumbersome to use; on the other hand, they are slightly faster and, for developers who already know STL, have the advantage of familiarity.

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

The default QMap::iterator constructor creates an uninitialized iterator. You must initialize it using a QMap function like QMap::begin(), QMap::end(), or QMap::find() before you can start iterating. Here's a typical loop that prints all the (key, value) pairs stored in a map:

QMap<QString, int> map;
map.insert(“January”, 1);
map.insert(“February”, 2);
...
map.insert(“December”, 12);
QMap<QString, int>::iterator i;
for (i = map.begin(); i != map.end(); ++i)
      cout << i.key() << “: “ << i.value() << endl;

Unlike QHash, which stores its items in an arbitrary order, QMap stores its items ordered by key. Items that share the same key (because they were inserted using QMap::insertMulti(), or due to a unite()) will appear consecutively, from the most recently to the least recently inserted value.

Let's see a few examples of things we can do with a QMap::iterator that we cannot do with a QMap::const_iterator. Here's an example that increments every value stored in the QMap by 2:

QMap<QString, int>::iterator i;
for (i = map.begin(); i != map.end(); ++i)
      i.value() += 2;

Here's an example that removes all the items whose key is a string that starts with an underscore character:

QMap<QString, int>::iterator i = map.begin();
while (i != map.end()) {
      if (i.key().startsWith(‘_’))
          i = map.erase(i);
      else
          ++i;
}

The call to QMap::erase() removes the item pointed to by the iterator from the map, and returns an iterator to the next item. Here's another way of removing an item while iterating:

QMap<QString, int>::iterator i = map.begin();
while (i != map.end()) {
      QMap<QString, int>::iterator prev = i;
      ++i;
      if (prev.key().startsWith(‘_’))
          map.erase(prev);
}

It might be tempting to write code like this:

// WRONG
while (i != map.end()) {
      if (i.key().startsWith(‘_’))
          map.erase(i);
      ++i;
}

However, this will potentially crash in ++i, because i is a dangling iterator after the call to erase().

Multiple iterators can be used on the same map. If you add items to the map, existing iterators will remain valid. If you remove items from the map, iterators that point to the removed items will become dangling iterators.

Warning: Iterators on implicitly shared containers do not work exactly like STL-iterators. You should avoid copying a container while iterators are active on that container. For more information, read Implicit sharing iterator problem.

pub unsafe fn dec(&self) -> Ref<Iterator>

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

Calls C++ function: QMap<int, QVariant>::iterator& QMap<int, QVariant>::iterator::operator--().

C++ documentation:

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

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

See also operator++().

pub unsafe fn dec_postfix(&self, arg1: c_int) -> CppBox<Iterator>

This is an overloaded function.

Calls C++ function: QMap<int, QVariant>::iterator QMap<int, QVariant>::iterator::operator--(int arg1).

C++ documentation:

This is an overloaded function.

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

pub unsafe fn inc(&self) -> Ref<Iterator>

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

Calls C++ function: QMap<int, QVariant>::iterator& QMap<int, QVariant>::iterator::operator++().

C++ documentation:

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

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

See also operator--().

pub unsafe fn inc_postfix(&self, arg1: c_int) -> CppBox<Iterator>

This is an overloaded function.

Calls C++ function: QMap<int, QVariant>::iterator QMap<int, QVariant>::iterator::operator++(int arg1).

C++ documentation:

This is an overloaded function.

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

pub unsafe fn indirection(&self) -> Ref<QVariant>

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

Calls C++ function: QVariant& QMap<int, QVariant>::iterator::operator*() const.

C++ documentation:

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

Same as value().

See also key().

pub unsafe fn key(&self) -> *const c_int

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

Calls C++ function: const int& QMap<int, QVariant>::iterator::key() const.

C++ documentation:

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 QHash::erase() followed by QHash::insert() or QHash::insertMulti().

See also value().

pub unsafe fn new() -> CppBox<Iterator>

Constructs an uninitialized iterator.

Calls C++ function: [constructor] void QMap<int, QVariant>::iterator::iterator().

C++ documentation:

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 QMap::begin() and QMap::end().

pub unsafe fn new_copy(other: impl CastInto<Ref<Iterator>>) -> CppBox<Iterator>

The QMap::iterator class provides an STL-style non-const iterator for QMap and QMultiMap.

Calls C++ function: [constructor] void QMap<int, QVariant>::iterator::iterator(const QMap<int, QVariant>::iterator& other).

C++ documentation:

The QMap::iterator class provides an STL-style non-const iterator for QMap and QMultiMap.

QMap features both STL-style iterators and Java-style iterators. The STL-style iterators are more low-level and more cumbersome to use; on the other hand, they are slightly faster and, for developers who already know STL, have the advantage of familiarity.

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

The default QMap::iterator constructor creates an uninitialized iterator. You must initialize it using a QMap function like QMap::begin(), QMap::end(), or QMap::find() before you can start iterating. Here's a typical loop that prints all the (key, value) pairs stored in a map:

QMap<QString, int> map;
map.insert(“January”, 1);
map.insert(“February”, 2);
...
map.insert(“December”, 12);
QMap<QString, int>::iterator i;
for (i = map.begin(); i != map.end(); ++i)
      cout << i.key() << “: “ << i.value() << endl;

Unlike QHash, which stores its items in an arbitrary order, QMap stores its items ordered by key. Items that share the same key (because they were inserted using QMap::insertMulti(), or due to a unite()) will appear consecutively, from the most recently to the least recently inserted value.

Let's see a few examples of things we can do with a QMap::iterator that we cannot do with a QMap::const_iterator. Here's an example that increments every value stored in the QMap by 2:

QMap<QString, int>::iterator i;
for (i = map.begin(); i != map.end(); ++i)
      i.value() += 2;

Here's an example that removes all the items whose key is a string that starts with an underscore character:

QMap<QString, int>::iterator i = map.begin();
while (i != map.end()) {
      if (i.key().startsWith(‘_’))
          i = map.erase(i);
      else
          ++i;
}

The call to QMap::erase() removes the item pointed to by the iterator from the map, and returns an iterator to the next item. Here's another way of removing an item while iterating:

QMap<QString, int>::iterator i = map.begin();
while (i != map.end()) {
      QMap<QString, int>::iterator prev = i;
      ++i;
      if (prev.key().startsWith(‘_’))
          map.erase(prev);
}

It might be tempting to write code like this:

// WRONG
while (i != map.end()) {
      if (i.key().startsWith(‘_’))
          map.erase(i);
      ++i;
}

However, this will potentially crash in ++i, because i is a dangling iterator after the call to erase().

Multiple iterators can be used on the same map. If you add items to the map, existing iterators will remain valid. If you remove items from the map, iterators that point to the removed items will become dangling iterators.

Warning: Iterators on implicitly shared containers do not work exactly like STL-iterators. You should avoid copying a container while iterators are active on that container. For more information, read Implicit sharing iterator problem.

pub unsafe fn struct_deref(&self) -> Ptr<QVariant>

Returns a pointer to the current item's value.

Calls C++ function: QVariant* QMap<int, QVariant>::iterator::operator->() const.

C++ documentation:

Returns a pointer to the current item’s value.

See also value().

pub unsafe fn sub_assign(&self, j: c_int) -> Ref<Iterator>

Makes the iterator go back by j items. (If j is negative, the iterator goes forward.)

Calls C++ function: QMap<int, QVariant>::iterator& QMap<int, QVariant>::iterator::operator-=(int j).

C++ documentation:

Makes the iterator go back by j items. (If j is negative, the iterator goes forward.)

See also operator+=() and operator-().

pub unsafe fn value(&self) -> Ref<QVariant>

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

Calls C++ function: QVariant& QMap<int, QVariant>::iterator::value() const.

C++ documentation:

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, for example:

if (i.key() == “Hello”)
      i.value() = “Bonjour”;

See also key() and operator*().

Trait Implementations

impl Add<i32> for &Iterator

fn add(self, j: c_int) -> CppBox<Iterator>

Returns an iterator to the item at j positions forward from this iterator. (If j is negative, the iterator goes backward.)

Calls C++ function: QMap<int, QVariant>::iterator QMap<int, QVariant>::iterator::operator+(int j) const.

C++ documentation:

Returns an iterator to the item at j positions forward from this iterator. (If j is negative, the iterator goes backward.)

This operation can be slow for large j values.

See also operator-().

type Output = CppBox<Iterator>

The resulting type after applying the + operator.

impl CppDeletable for Iterator

unsafe fn delete(&self)

The QMap::iterator class provides an STL-style non-const iterator for QMap and QMultiMap.

Calls C++ function: [destructor] void QMap<int, QVariant>::iterator::~iterator().

C++ documentation:

The QMap::iterator class provides an STL-style non-const iterator for QMap and QMultiMap.

QMap features both STL-style iterators and Java-style iterators. The STL-style iterators are more low-level and more cumbersome to use; on the other hand, they are slightly faster and, for developers who already know STL, have the advantage of familiarity.

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

The default QMap::iterator constructor creates an uninitialized iterator. You must initialize it using a QMap function like QMap::begin(), QMap::end(), or QMap::find() before you can start iterating. Here's a typical loop that prints all the (key, value) pairs stored in a map:

QMap<QString, int> map;
map.insert(“January”, 1);
map.insert(“February”, 2);
...
map.insert(“December”, 12);
QMap<QString, int>::iterator i;
for (i = map.begin(); i != map.end(); ++i)
      cout << i.key() << “: “ << i.value() << endl;

Unlike QHash, which stores its items in an arbitrary order, QMap stores its items ordered by key. Items that share the same key (because they were inserted using QMap::insertMulti(), or due to a unite()) will appear consecutively, from the most recently to the least recently inserted value.

Let's see a few examples of things we can do with a QMap::iterator that we cannot do with a QMap::const_iterator. Here's an example that increments every value stored in the QMap by 2:

QMap<QString, int>::iterator i;
for (i = map.begin(); i != map.end(); ++i)
      i.value() += 2;

Here's an example that removes all the items whose key is a string that starts with an underscore character:

QMap<QString, int>::iterator i = map.begin();
while (i != map.end()) {
      if (i.key().startsWith(‘_’))
          i = map.erase(i);
      else
          ++i;
}

The call to QMap::erase() removes the item pointed to by the iterator from the map, and returns an iterator to the next item. Here's another way of removing an item while iterating:

QMap<QString, int>::iterator i = map.begin();
while (i != map.end()) {
      QMap<QString, int>::iterator prev = i;
      ++i;
      if (prev.key().startsWith(‘_’))
          map.erase(prev);
}

It might be tempting to write code like this:

// WRONG
while (i != map.end()) {
      if (i.key().startsWith(‘_’))
          map.erase(i);
      ++i;
}

However, this will potentially crash in ++i, because i is a dangling iterator after the call to erase().

Multiple iterators can be used on the same map. If you add items to the map, existing iterators will remain valid. If you remove items from the map, iterators that point to the removed items will become dangling iterators.

Warning: Iterators on implicitly shared containers do not work exactly like STL-iterators. You should avoid copying a container while iterators are active on that container. For more information, read Implicit sharing iterator problem.

impl Decrement for Iterator

unsafe fn dec(&self) -> Ref<Iterator>

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

Calls C++ function: QMap<int, QVariant>::iterator& QMap<int, QVariant>::iterator::operator--().

C++ documentation:

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

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

See also operator++().

type Output = Ref<Iterator>

Output type.

impl Increment for Iterator

unsafe fn inc(&self) -> Ref<Iterator>

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

Calls C++ function: QMap<int, QVariant>::iterator& QMap<int, QVariant>::iterator::operator++().

C++ documentation:

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

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

See also operator--().

type Output = Ref<Iterator>

Output type.

impl Indirection for Iterator

unsafe fn indirection(&self) -> Ref<QVariant>

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

Calls C++ function: QVariant& QMap<int, QVariant>::iterator::operator*() const.

C++ documentation:

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

Same as value().

See also key().

type Output = Ref<QVariant>

Output type.

impl PartialEq<Ref<ConstIterator>> for Iterator

fn eq(&self, o: &Ref<ConstIterator>) -> bool

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

Calls C++ function: bool QMap<int, QVariant>::iterator::operator==(const QMap<int, QVariant>::const_iterator& o) const.

C++ documentation:

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

See also operator!=().

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialEq<Ref<Iterator>> for Iterator

fn eq(&self, o: &Ref<Iterator>) -> bool

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

Calls C++ function: bool QMap<int, QVariant>::iterator::operator==(const QMap<int, QVariant>::iterator& o) const.

C++ documentation:

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

See also operator!=().

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Sub<i32> for &Iterator

fn sub(self, j: c_int) -> CppBox<Iterator>

Returns an iterator to the item at j positions backward from this iterator. (If j is negative, the iterator goes forward.)

Calls C++ function: QMap<int, QVariant>::iterator QMap<int, QVariant>::iterator::operator-(int j) const.

C++ documentation:

Returns an iterator to the item at j positions backward from this iterator. (If j is negative, the iterator goes forward.)

This operation can be slow for large j values.

See also operator+().

type Output = CppBox<Iterator>

The resulting type after applying the - operator.