QMqttTopicFilter Class
The QMqttTopicFilter class represents a MQTT topic filter. More...
| Header: | #include <QMqttTopicFilter> |
| CMake: | find_package(Qt6 REQUIRED COMPONENTS Mqtt) target_link_libraries(mytarget PRIVATE Qt6::Mqtt) |
| qmake: | QT += mqtt |
Note: All functions in this class are reentrant.
Public Types
| enum | MatchOption { NoMatchOption, WildcardsDontMatchDollarTopicMatchOption } |
| flags | MatchOptions |
Public Functions
| QMqttTopicFilter(const QMqttTopicFilter &filter) | |
| QMqttTopicFilter(const QLatin1String &filter) | |
| QMqttTopicFilter(const QString &filter = QString()) | |
| QMqttTopicFilter & | operator=(const QMqttTopicFilter &filter) |
| ~QMqttTopicFilter() | |
| QString | filter() const |
| bool | isValid() const |
| bool | match(const QMqttTopicName &name, QMqttTopicFilter::MatchOptions matchOptions = NoMatchOption) const |
| void | setFilter(const QString &filter) |
| QString | sharedSubscriptionName() const |
| void | swap(QMqttTopicFilter &other) |
Related Non-Members
| bool | operator!=(const QMqttTopicFilter &lhs, const QMqttTopicFilter &rhs) |
| bool | operator<(const QMqttTopicFilter &lhs, const QMqttTopicFilter &rhs) |
| QDataStream & | operator<<(QDataStream &out, const QMqttTopicFilter &filter) |
| bool | operator==(const QMqttTopicFilter &lhs, const QMqttTopicFilter &rhs) |
| QDataStream & | operator>>(QDataStream &in, QMqttTopicFilter &filter) |
Detailed Description
QMqttTopicFilter is a thin wrapper around a QString providing an expressive data type for MQTT topic filters. Beside the benefits of having a strong type preventing unintended misuse, QMqttTopicFilter provides convenient functions related to topic filters like isValid() or match().
For example, the following code would fail to compile and prevent a possible unintended and meaningless matching of two filters, especially if the variable names were less expressive:
QMqttTopicFilter globalFilter{"foo/#"}; QMqttTopicFilter specificFilter{"foo/bar"}; if (globalFilter.match(specificFilter)) { //... }
The usability, however, is not affected since the following snippet compiles and runs as expected:
QMqttTopicFilter globalFilter{"foo/#"}; if (globalFilter.match("foo/bar")) { //... }
See also QMqttTopicName.
Member Type Documentation
enum QMqttTopicFilter::MatchOption
flags QMqttTopicFilter::MatchOptions
This enum value holds the matching options for the topic filter.
| Constant | Value | Description |
|---|---|---|
QMqttTopicFilter::NoMatchOption | 0x0000 | No match options are set. |
QMqttTopicFilter::WildcardsDontMatchDollarTopicMatchOption | 0x0001 | A wildcard at the filter's beginning does not match a topic name that starts with the dollar sign ($). |
The MatchOptions type is a typedef for QFlags<MatchOption>. It stores an OR combination of MatchOption values.
Member Function Documentation
QMqttTopicFilter::QMqttTopicFilter(const QMqttTopicFilter &filter)
Creates a new MQTT topic filter as a copy of filter.
QMqttTopicFilter::QMqttTopicFilter(const QLatin1String &filter)
Creates a new MQTT topic filter with the specified filter.
QMqttTopicFilter::QMqttTopicFilter(const QString &filter = QString())
Creates a new MQTT topic filter with the specified filter.
QMqttTopicFilter &QMqttTopicFilter::operator=(const QMqttTopicFilter &filter)
Assigns the MQTT topic filter filter to this object, and returns a reference to the copy.
QMqttTopicFilter::~QMqttTopicFilter()
Destroys the QMqttTopicFilter object.
QString QMqttTopicFilter::filter() const
Returns the topic filter.
See also setFilter().
bool QMqttTopicFilter::isValid() const
Returns true if the topic filter is valid according to the MQTT standard section 4.7, or false otherwise.
bool QMqttTopicFilter::match(const QMqttTopicName &name, QMqttTopicFilter::MatchOptions matchOptions = NoMatchOption) const
Returns true if the topic filter matches the topic name name honoring the given matchOptions, or false otherwise.
void QMqttTopicFilter::setFilter(const QString &filter)
Sets the topic filter to filter.
See also filter().
[since 5.12] QString QMqttTopicFilter::sharedSubscriptionName() const
Returns the name of a share if the topic filter has been specified as a shared subscription. The format of shared subscriptions is defined as $share/sharename/topicfilter.
This function was introduced in Qt 5.12.
void QMqttTopicFilter::swap(QMqttTopicFilter &other)
Swaps the MQTT topic filter other with this MQTT topic filter. This operation is very fast and never fails.
Related Non-Members
bool operator!=(const QMqttTopicFilter &lhs, const QMqttTopicFilter &rhs)
Returns true if the topic filters lhs and rhs are different, otherwise returns false.
bool operator<(const QMqttTopicFilter &lhs, const QMqttTopicFilter &rhs)
Returns true if the topic filter lhs is lexically less than the topic filter rhs; otherwise returns false.
QDataStream &operator<<(QDataStream &out, const QMqttTopicFilter &filter)
Writes the topic filter filter to the stream out and returns a reference to the stream.
See also Format of the QDataStream operators.
bool operator==(const QMqttTopicFilter &lhs, const QMqttTopicFilter &rhs)
Returns true if the topic filters lhs and rhs are equal, otherwise returns false.
QDataStream &operator>>(QDataStream &in, QMqttTopicFilter &filter)
Reads a topic filter into filter from the stream in and returns a reference to the stream.
See also Format of the QDataStream operators.