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juce_CallbackListenerList.h
/*
==============================================================================
This file is part of the JUCE library.
Copyright (c) 2022 - Raw Material Software Limited
JUCE is an open source library subject to commercial or open-source
licensing.
By using JUCE, you agree to the terms of both the JUCE 7 End-User License
Agreement and JUCE Privacy Policy.
End User License Agreement: www.juce.com/juce-7-licence
Privacy Policy: www.juce.com/juce-privacy-policy
Or: You may also use this code under the terms of the GPL v3 (see
www.gnu.org/licenses).
JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
DISCLAIMED.
==============================================================================
*/
namespace juce::detail
{
template <typename... Ts>
constexpr bool isValueOrLvalueReferenceToConst()
{
return (( (! std::is_reference_v<Ts>)
|| (std::is_lvalue_reference_v<Ts> && std::is_const_v<std::remove_reference_t<Ts>>)) && ...);
}
template <typename... Args>
class CallbackListenerList
{
public:
static_assert (isValueOrLvalueReferenceToConst<Args...>(),
"CallbackListenerList can only forward values or const lvalue references");
using Callback = std::function<void (Args...)>;
ErasedScopeGuard addListener (Callback callback)
{
jassert (callback != nullptr);
const auto it = callbacks.insert (callbacks.end(), std::move (callback));
listeners.add (&*it);
return ErasedScopeGuard { [this, it]
{
listeners.remove (&*it);
callbacks.erase (it);
} };
}
void call (Args... args)
{
listeners.call ([&] (auto& l) { l (std::forward<Args> (args)...); });
}
private:
std::list<Callback> callbacks;
ListenerList<Callback> listeners;
};
} // namespace juce::detail