On 03/06/2012 18:36, Eric Niebler wrote:
Plus I don't have a good way to distinguish between a terminal of
shared_ptr<T> and a terminal of T which is held through a shared_ptr.
Have you tried a grammar? Something like (untested) proto::terminal<
boost::shared_ptr< proto::_> > ?
That would match expressions of the form (assuming I have binary plus in
my grammar)
shared_ptr<T> p1, p2.
p1 + p2;
This is exactly what I do not want. I don't want my grammar to be
cluttered by implementation details. It makes no sense semantically for
shared_ptr to be values, it's just a technique used for life time
management of specific values.
If I ever introduced shared_ptrs as values in my grammar, they might do
something entirely different.
To separate this more or less cleanly, I use a special tag for nullary
expressions where shared_ptr is just an implementation detail, but it's
still not really satisfying since the value doesn't have the right type
in the tree.
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