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Check for nullptr comparison operator in NullCheckedInvocation::invoke()

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ed 2021-12-07 15:32:37 +00:00
parent 112f8999fd
commit 4c2c51eaf4
1 changed files with 22 additions and 5 deletions
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27
modules/juce_core/misc/juce_Functional.h
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@ -23,24 +23,41 @@
namespace juce
{
namespace detail
{
template <typename...>
using Void = void;
template <typename, typename = void>
struct EqualityComparableToNullptr
: std::false_type {};
template <typename T>
struct EqualityComparableToNullptr<T, Void<decltype (std::declval<T>() != nullptr)>>
: std::true_type {};
} // namespace detail
//==============================================================================
/** Some helper methods for checking a callable object before invoking with
the specified arguments.
If the object is a std::function it will check for nullptr before
calling. For a callable object it will invoke the function call operator.
If the object provides a comparison operator for nullptr it will check before
calling. For other objects it will just invoke the function call operator.
@tags{Core}
*/
struct NullCheckedInvocation
{
template <typename... Signature, typename... Args>
static void invoke (const std::function<Signature...>& fn, Args&&... args)
template <typename Callable, typename... Args,
std::enable_if_t<detail::EqualityComparableToNullptr<Callable>::value, int> = 0>
static void invoke (Callable&& fn, Args&&... args)
{
if (fn != nullptr)
fn (std::forward<Args> (args)...);
}
template <typename Callable, typename... Args>
template <typename Callable, typename... Args,
std::enable_if_t<! detail::EqualityComparableToNullptr<Callable>::value, int> = 0>
static void invoke (Callable&& fn, Args&&... args)
{
fn (std::forward<Args> (args)...);