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[iter] Add hb_map() 

Untested.
This commit is contained in:
Behdad Esfahbod 2019-01-09 11:15:49 -08:00
parent f7fcc47641
commit 1733e4702c
1 changed files with 42 additions and 1 deletions
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43
src/hb-iter.hh
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@ -198,6 +198,48 @@ struct hb_is_iterator_of { enum {
* Adaptors, combiners, etc.
*/
/* hb_map(), hb_filter(), hb_reduce() */
template <typename Iter, typename Proj,
hb_enable_if (hb_is_iterator (Iter))>
struct hb_map_iter_t :
hb_iter_t<hb_map_iter_t<Iter, Proj>, decltype (f (*hb_declval (typename Iter::item_t)))>
{
hb_map_iter_t (const Iter& it, Proj f) : it (it), f (f) {}
typedef decltype (f (*hb_declval (typename Iter::item_t))) __item_t__;
enum { is_random_access_iterator = Iter::is_random_access_iterator };
__item_t__ __item__ () const { return f (*it); }
__item_t__ __item_at__ (unsigned i) const { return f (it[i]); }
bool __more__ () const { return it; }
unsigned __len__ () const { return it.len (); }
void __next__ () { ++it; }
void __forward__ (unsigned n) { it += n; }
void __prev__ () { --it; }
void __rewind__ (unsigned n) { it -= n; }
private:
Iter it;
Proj f;
};
template <typename Proj>
struct hb_map_iter_factory_t
{
hb_map_iter_factory_t (Proj f) : f (f) {}
template <typename Iterable,
hb_enable_if (hb_is_iterable (Iterable))>
hb_map_iter_t<typename Iterable::iter_t, Proj> operator () (const Iterable &c)
{ return hb_map_iter_t<typename Iterable::iter_t, Proj> (c.iter (), f); }
private:
Proj f;
};
template <typename Proj>
inline hb_map_iter_factory_t<Proj>
hb_map (Proj f)
{ return hb_map_iter_factory_t<Proj> (f); }
/* hb_zip() */
@ -228,7 +270,6 @@ struct hb_zip_iter_t :
A a;
B b;
};
template <typename A, typename B,
hb_enable_if (hb_is_iterable (A) && hb_is_iterable (B))>
inline hb_zip_iter_t<typename A::iter_t, typename B::iter_t>