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[iter] Take start value in hb_enumerate() 

Also rewrite it via composition.
This commit is contained in:
Behdad Esfahbod 2019-05-09 11:07:38 -07:00
parent 7675d0d3a6
commit 2c24ea37b1
2 changed files with 14 additions and 48 deletions
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61
src/hb-iter.hh
View File

@ -490,58 +490,11 @@ struct
template <typename A, typename B,
hb_requires (hb_is_iterable (A) && hb_is_iterable (B))>
hb_zip_iter_t<hb_iter_type<A>, hb_iter_type<B>>
operator () (A& a, B &b) const
operator () (A&& a, B&& b) const
{ return hb_zip_iter_t<hb_iter_type<A>, hb_iter_type<B>> (hb_iter (a), hb_iter (b)); }
}
HB_FUNCOBJ (hb_zip);
/* hb_enumerate */
template <typename Iter,
hb_requires (hb_is_iterator (Iter))>
struct hb_enumerate_iter_t :
hb_iter_t<hb_enumerate_iter_t<Iter>,
hb_pair_t<unsigned, typename Iter::item_t>>
{
hb_enumerate_iter_t (const Iter& it) : i (0), it (it) {}
typedef hb_pair_t<unsigned, typename Iter::item_t> __item_t__;
static constexpr bool is_random_access_iterator = Iter::is_random_access_iterator;
static constexpr bool is_sorted_iterator = true;
__item_t__ __item__ () const { return __item_t__ (+i, *it); }
__item_t__ __item_at__ (unsigned j) const { return __item_t__ (i + j, it[j]); }
bool __more__ () const { return bool (it); }
unsigned __len__ () const { return it.len (); }
void __next__ () { ++i; ++it; }
void __forward__ (unsigned n) { i += n; it += n; }
void __prev__ () { --i; --it; }
void __rewind__ (unsigned n) { i -= n; it -= n; }
hb_enumerate_iter_t __end__ () const
{
if (is_random_access_iterator)
return *this + this->len ();
/* Above expression loops twice. Following loops once. */
auto it = *this;
while (it) ++it;
return it;
}
bool operator != (const hb_enumerate_iter_t& o) const
{ return i != o.i || it != o.it; }
private:
unsigned i;
Iter it;
};
struct
{
template <typename Iterable,
hb_requires (hb_is_iterable (Iterable))>
hb_enumerate_iter_t<hb_iter_type<Iterable>>
operator () (Iterable&& it) const
{ return hb_enumerate_iter_t<hb_iter_type<Iterable>> (hb_iter (it)); }
}
HB_FUNCOBJ (hb_enumerate);
/* hb_apply() */
template <typename Appl>
@ -629,6 +582,18 @@ struct
}
HB_FUNCOBJ (hb_range);
/* hb_enumerate */
struct
{
template <typename Iterable,
typename Index = unsigned,
hb_requires (hb_is_iterable (Iterable))>
auto operator () (Iterable&& it, Index start = 0u) const HB_AUTO_RETURN
( hb_zip (hb_iota (start), it) )
}
HB_FUNCOBJ (hb_enumerate);
/* hb_sink() */

1
src/test-iter.cc
View File

@ -158,6 +158,7 @@ main (int argc, char **argv)
test_iterator (hb_zip (st, v));
test_iterator_non_default_constructable (hb_enumerate (st));
test_iterator_non_default_constructable (hb_enumerate (st, -5));
test_iterator_non_default_constructable (hb_enumerate (hb_iter (st)));
test_iterator_non_default_constructable (hb_enumerate (hb_iter (st) + 1));
test_iterator_non_default_constructable (hb_iter (st) | hb_filter ());