MatchEvent

Стаття
10/29/2021

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The MatchEvent function is used to match an event against a list of event types. If the event matches a type in the list, it's forwarded to a handler for further processing.

Syntax

template <
    typename        TEvent,
    typename...     TEvents,
    typename        TCallable,
    typename...     TExtraArgs>
bool MatchEvent(
    const RawEvent& event,
    TCallable&&     callable,
    TExtraArgs&&... extraArgs);

Parameters

TEvent
The first event type that you wish to match.

TEvents
The remaining event types that you wish to match.

TCallable
A type that supports operator(). For more information on which arguments get passed to this operator, see the callable parameter description.

TExtraArgs
The types of the extra arguments that were passed to MatchEvent.

event
The event to match against the event types described by TEvent and TEvents.

callable
MatchEvent invokes callable after successfully matching the event with any of the event types described by TEvent and TEvents. The first argument passed to callable is an r-value of the matched event type. The extraArgs parameter pack is perfect-forwarded in the remaining parameters of callable.

extraArgs
The arguments that get perfect-forwarded to callable along with the matched event type.

Return Value

A bool value that's true if matching was successful, or false otherwise.

Remarks

Event types to use for the TEvent and TEvents parameters are selected from a list of capture classes. For a list of events and the capture classes you can use to match them, see event table.

Example

void MyClass::OnStartActivity(const EventStack& eventStack)
{
    // Let's assume eventStack contains:
    // [Compiler, BackEndPass, C2DLL, CodeGeneration, Thread, Function]

    auto& functionEvent = eventStack.Back(); // The Function event

    bool b1 = MatchEvent<Function, Thread>(
        functionEvent, [](auto matchedEvent){ /* Do something... */});

    bool b2 = MatchEvent<CodeGeneration, Thread>(
        functionEvent, [](auto matchedEvent){ /* Do something... */});


    // b1: true because the list of types contains Function, which is
    //     the type of the event we are trying to match.
    // b2: false because the list of types doesn't contain Function.
}

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