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Exception-less overload of 'Id_space::apply'

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This patch allows the use of the 'Id_space' utility without catching
'Unknown_id' exceptions. Instead, the new 'apply' overload takes a
second functor 'missing_fn' as argument, which is called whenever the
lookup fails.

Issue #5244
This commit is contained in:
Norman Feske 2024-06-10 16:41:10 +02:00
parent 73d18261dc
commit 7c91596922
1 changed files with 27 additions and 14 deletions
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41
repos/base/include/base/id_space.h
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@ -182,6 +182,31 @@ class Genode::Id_space : public Noncopyable
_elements.first()->template _for_each<ARG>(fn);
}
/**
* Apply functor 'fn' to object with given ID, or call 'missing_fn'
*
* See 'for_each' for a description of the 'ARG' argument.
* If the ID is not known, 'missing_fn' is called instead of 'fn'.
* Both 'fn' and 'missing_fn' must have the same return type.
*/
template <typename ARG, typename FN>
auto apply(Id id, FN const &fn, auto const &missing_fn)
-> typename Trait::Functor<decltype(&FN::operator())>::Return_type
{
T *obj_ptr = nullptr;
{
Mutex::Guard guard(_mutex);
if (_elements.first())
if (Element *e = _elements.first()->_lookup(id))
obj_ptr = &e->_obj;
}
if (obj_ptr)
return fn(static_cast<ARG &>(*obj_ptr));
else
return missing_fn();
}
/**
* Apply functor 'fn' to object with given ID
*
@ -193,20 +218,8 @@ class Genode::Id_space : public Noncopyable
auto apply(Id id, FN const &fn)
-> typename Trait::Functor<decltype(&FN::operator())>::Return_type
{
T *obj = nullptr;
{
Mutex::Guard guard(_mutex);
if (!_elements.first())
throw Unknown_id();
if (Element *e = _elements.first()->_lookup(id))
obj = &e->_obj;
}
if (obj)
return fn(static_cast<ARG &>(*obj));
else
throw Unknown_id();
using Result = typename Trait::Functor<decltype(&FN::operator())>::Return_type;
return apply<ARG>(id, fn, [&] () -> Result { throw Unknown_id(); });
}
/**