On Sat, Jan 8, 2011 at 10:16 AM, caustik <caustik@gmail.com> wrote:
On Sat, Jan 8, 2011 at 10:03 AM, Hartmut Kaiser <hartmut.kaiser@gmail.com>wrote:
I might give that a shot as I can't seem to get local variables to solve my problem. I would expect these two commands to have the same result (albeit unnecessarily assigning the _a variable, which just gets tossed away anyway), but apparently they are not?
r = p[_a = _1] r = p
Automatic attribute propagation from the rhs expression to the lhs rule is disabled as soon as semantic actions are involved. If you want to enforce attribute propagation anyways, write:
rule<...> r; r %= p[...];
If the rhs has no semantic actions attached, operator=() behaves exactly like operator%=().
That does the trick. Apologies for the previous top-post. I've been out of the mailing list game for a while now =)
This style ended up working and I can finally move on to other things:
r %= p1[_a = _1] >> ('*' | (eps[bind(&class::undo, &instance, _a)] >> !eps))
p2
FWIW, this should do the same, but simpler:
r %= p1[_a = _1] >> ('*' | !eps[bind(&class::undo, &instance, _a)]) >> p2;
Ah, I was thinking that ! behaved like this:
(!eps)[action]
as opposed to this:
!(eps[action])
Now, suppose to avoid all this, you want to instead just have each rule return a shared_ptr e.g.: rule<Iterator, shared_ptr<MyClass>()> start; Except, you don't want to call "delete" on MyClass* but instead you want to call your custom cleanup function. So, is there a way to tell your rule what parameters to pass to it's synthesized attribute's constructor, so that they construct like this: shared_ptr<MyClass> synthAttr(ptr, myDeleter);