[Boost-users] [Coroutine] Assertion when coroutine is not run

Subject: [Boost-users] [Coroutine] Assertion when coroutine is not run
From: Brian Ravnsgaard Riis (brian_at_[hidden])
Date: 2014-03-09 20:37:45

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Hi,

I've been toying with Boost.Coroutine lately. For starters I have
tried to implement a message parser using the library. For this
purpose I have two coroutine<char>::push_type in a containing class.
These are initialized at class construction with a lambda. One
coroutine parses the message header, the other the body.

This all worked fine. Until I had a test case where I was only
interested in the message header, so I never called the
message-body-coroutine. At object destruction I get a this assertion:

replyparser:
/usr/local/include/boost/coroutine/detail/push_coroutine_object.hpp:167:
void boost::coroutines::detail::push_coroutine_object<char, <lambda at
src/replyparser.cpp:303:22>,
boost::coroutines::detail::standard_stack_allocator,
std::allocator<boost::coroutines::push_coroutine<char> >,
boost::coroutines::pull_coroutine<char> >::run() [X = char, Y =
<lambda at src/replyparser.cpp:303:22>, Z =
boost::coroutines::detail::standard_stack_allocator, V =
std::allocator<boost::coroutines::push_coroutine<char> >, W =
boost::coroutines::pull_coroutine<char>]: Assertion `hldr_from->data'
failed.

The message-body coroutine is really simple; it just takes the
characters and stuffs them into a std::string until the string size is
equal to the expected length of the body (parsed from the header):

[&](coroutine<char>::pull_type& c)
{
    content.push_back(c.get());
    while(content.size() != contentLength)
    {
        c();
        content.push_back(c.get());
    }
    validResult = true;
}

This works just fine when I parse the message body, but when I (choose
to) ignore the message body, so the coroutine is never called, I get
the above assertion.

I have a feeling I'm missing some obvious detail about this. Of course
I would normally not skip the message body, but there is a chance the
length is 0, i.e. there *is* no message body. I'd prefer to have no
assertions in that case.

What am I doing wrong?

 /Brian Riis
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