[patch 2/N] std::regex refactoring - sub _Executor for lookahead

[Jonathan Wakely]

On 28/04/14 10:18 -0400, Tim Shen wrote:
>On Mon, Apr 28, 2014 at 8:45 AM, Jonathan Wakely <jwakely@redhat.com> wrote:
>> Is there any reason this object is created on the heap?
>
>Say, _Executor's size is so huge and a uncommon user gets a stack
>overflow by keep invoking this function?

Ah yes, I didn't think of that. But the size of _Executor is fixed,
isn't it?  If it has a huge number of states or matches those will be
on the heap anyway, in vectors/arrays.

It could be huge if instantiated with a huge iterator type, as it
stores three members of the iterator type, but I don't think users
should be too surprised if they overflow the stack with freakishly
large iterators :-)

Am I still missing something?

(I don't have a preference for whether to change this, but if we keep
it on the heap we should add a comment, or I'll keep forgetting the
rationale and try to change it again!)