Re: [pdf-devel] Patch for FS#93 stack based iterators

[Michael Gold]

On Tue, Jan 27, 2009 at 08:37:08 -0800, address@hidden wrote:
> Hi hackers,
> 
> I attach a patch for stack based iterators, in list and hash modules.
> 
> BTW, the current gnulib iterators are 28 bytes long, correct me if I'm wrong. 
> I gave 48 bytes to iterators, though this remains open to discussion.

They're 56 bytes on x86_64. Since all the struct's values are pointers
or size_t (which is pointer-sized on x86/x86_64), it would make sense to
use a type like intptr_t instead of char.

We should also verify
       sizeof(pdf_list_iterator_s) >= sizeof(gl_list_iterator_t)
       and sizeof(pdf_hash_iterator_s) >= sizeof(gl_list_iterator_t)

Is there a portable way to do this at compile time? If not, assertions
could be used in pdf_{list,hash}_iterator.

I'm not sure how much padding we should have. The 'i' and 'j' fields are
already unused by gnulib, effectively making our structure more than
twice as large as necessary; but programs probably won't be allocating
more than 1 or 2 iterators at a time, so I'd say it's fine as it is now
(sizeof(intptr_t)*12).

Are the _iterator_free methods necessary? gl_list_iterator_free doesn't
do anything, and it would be a bit simpler to use the types without
them. If _iterator can't fail with ENOMEM, I don't see what we'd need to
free in the future.

-- Michael

signature.asc
Description: Digital signature