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[iter] Handhold hb_is_iterator() type deduction 

by partial-instantiating on Iter.
This commit is contained in:
Behdad Esfahbod 2019-01-07 17:24:23 -05:00
parent cb5011d364
commit ed4336680d
1 changed files with 11 additions and 7 deletions
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18
src/hb-iter.hh
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@ -161,15 +161,19 @@ struct hb_is_iterable { enum { value = _hb_is_iterable<T, hb_true_t>::value }; }
/* hb_is_iterator() / hb_is_sorted_iterator() */
template<typename Iter = void, typename Item = void> char _hb_is_iterator (...) { return 0; };
template<typename Iter, typename Item> int _hb_is_iterator (hb_iter_t<Iter, Item> *) { return 0; };
template<typename Iter, typename Item> int _hb_is_iterator (hb_iter_t<Iter, const Item> *) { return 0; };
template<typename Iter, typename Item> int _hb_is_iterator (hb_iter_t<Iter, Item&> *) { return 0; };
template<typename Iter, typename Item> int _hb_is_iterator (hb_iter_t<Iter, const Item&> *) { return 0; };
static_assert (sizeof (char) != sizeof (int), "");
template <typename Iter>
struct _hb_is_iterator
{
char operator () (...) { return 0; };
template<typename Item> int operator () (hb_iter_t<Iter, Item> *) { return 0; };
template<typename Item> int operator () (hb_iter_t<Iter, const Item> *) { return 0; };
template<typename Item> int operator () (hb_iter_t<Iter, Item&> *) { return 0; };
template<typename Item> int operator () (hb_iter_t<Iter, const Item&> *) { return 0; };
static_assert (sizeof (char) != sizeof (int), "");
};
template<typename Iter, typename Item>
struct hb_is_iterator { enum {
value = sizeof (int) == sizeof (_hb_is_iterator (hb_declval<Iter*> ())) }; };
value = sizeof (int) == sizeof (hb_declval<_hb_is_iterator<Iter>> () (hb_declval<Iter*> ())) }; };
#define hb_is_iterator(Iter, Item) hb_is_iterator<Iter, Item>::value
#define hb_is_sorted_iterator(Iter, Item) \