Hello,
I want to use boost::asio::read_until() and pass a functor as match condition.
But I don't get it to compile.
Here is my source code:
#include <boost/asio.hpp>
using namespace boost::asio;
using iterator = buffers_iterator<streambuf::const_buffers_type>;
struct completion_functor
{
std::pair<iterator, bool> operator()(iterator begin, iterator end) {
return {};
}
};
completion_functor functor;
static_assert(is_match_condition<completion_functor>::value,
"completion_functor must be match condition");
static_assert(is_match_condition<decltype(functor)>::value, "functor must be
match condition");
std::pair<iterator, bool> completion_func(iterator begin, iterator end) {
return functor(begin, end);
}
static_assert(is_match_condition<decltype(completion_func)>::value,
"completion_func must be match condition");
auto lambda = [](iterator begin, iterator end) -> std::pair<iterator, bool> {
return {};
};
static_assert(is_match_condition<decltype(lambda)>::value, "lambda must be
match condition");
std::pair<iterator, bool> completion_func2(iterator begin, iterator end) {
return lambda(begin, end);
}
static_assert(is_match_condition<decltype(completion_func2)>::value,
"completion_func2 must be match condition");
int main(int argc, char *argv[])
{
io_context ctx;
ip::tcp::socket s{ctx};
streambuf buffer;
read_until(s, buffer, '\n');
read_until(s, buffer, completion_func);
read_until(s, buffer, completion_func2);
// the following calls do not compile
// read_until(s, buffer, functor);
// read_until(s, buffer, lambda);
}
It seems, that boost::asio::is_match_condition<> does neither accept my
lammda-function nor my functor. The only completion handler, that I get
accepted, is a classic, free-standing function (and static class member
functions, too).
But in that function, calling the lambda or the functor does not seem to be a
problem for the compiler.
The documentation of read_until describes match_condition as "The function
object to be called to determine whether a match exists."
I would expect lambda functions and functors to be accepted as a function
object.
Do I have an error in the declaration of lambda or
completion_functor::operator()?
Does anybody now, how to get this working?
I tried boost_1_73_0 and boost_1_88_0 with g++ (Gentoo 14.3.1_p20250801 p4)
14.3.1 20250801 and clang version 20.1.8
Thanks in advance,
Klebsch Mario
Funktion | R&D
Tel: +49 (0) 531 38 701 718
Raum: Braunschweig, E20
Diese E-Mail und die an sie angehängten Dateien sind ausschließlich für
Personen oder Institutionen bestimmt, deren Namen oben aufgeführt sind. Sie
können Informationen enthalten, die durch das Berufsgeheimnis geschützt sind
und deren Weitergabe strengstens untersagt ist. Jede elektronische Nachricht
kann geändert werden. ACTIA lehnt jede Verantwortung für diese Nachricht ab.
Der Inhalt dieser Nachricht stellt keine Verpflichtung seitens unseres
Unternehmens dar. Wenn Sie kein Empfänger sind, weisen wir Sie darauf hin, dass
das Lesen, Vervielfältigen oder Verteilen strengstens untersagt ist. Wir bitten
Sie daher, uns umgehend über diesen Brief zu informieren und diese Nachricht
sowie eventuell beigefügte Unterlagen aus Ihrem Postfach zu löschen. Danke.
This e-mail and the files attached to it are intended exclusively for persons
or institutions whose names are listed above. They may contain information that
is protected by professional secrecy and the disclosure of which is strictly
prohibited. Any electronic message can be modified. ACTIA declines all
responsibility for this message. The content of this message does not represent
a commitment on the part of our company. If you are not a recipient, we would
like to point out that reading, copying or distribution is strictly prohibited.
We therefore ask you to inform us immediately about this letter and to delete
this message and any accompanying documents from your mailbox. Thank you.
_______________________________________________
Boost-users mailing list -- [email protected]
To unsubscribe send an email to [email protected]
https://lists.boost.org/mailman3/lists/boost-users.lists.boost.org/
Archived at:
https://lists.boost.org/archives/list/[email protected]/message/EFS3KB5CF4OT2FHLELO43GRZR4W6RWLY/
