diff options
Diffstat (limited to 'src/hb-iter.hh')
| -rw-r--r-- | src/hb-iter.hh | 123 |
1 files changed, 102 insertions, 21 deletions
diff --git a/src/hb-iter.hh b/src/hb-iter.hh index 87b8ed880..b57f37b13 100644 --- a/src/hb-iter.hh +++ b/src/hb-iter.hh @@ -43,17 +43,12 @@ * is writable, then the iterator returns lvalues, otherwise it * returns rvalues. * - * TODO Document more. - * - * If iterator implementation implements operator!=, then can be + * If iterator implementation implements operator!=, then it can be * used in range-based for loop. That already happens if the iterator * is random-access. Otherwise, the range-based for loop incurs * one traversal to find end(), which can be avoided if written * as a while-style for loop, or if iterator implements a faster - * __end__() method. - * TODO When opting in for C++17, address this by changing return - * type of .end()? - */ + * __end__() method. */ /* * Base classes for iterators. @@ -75,23 +70,20 @@ struct hb_iter_t iter_t* thiz () { return static_cast< iter_t *> (this); } public: - /* TODO: - * Port operators below to use hb_enable_if to sniff which method implements - * an operator and use it, and remove hb_iter_fallback_mixin_t completely. */ - /* Operators. */ iter_t iter () const { return *thiz(); } iter_t operator + () const { return *thiz(); } - iter_t begin () const { return *thiz(); } - iter_t end () const { return thiz()->__end__ (); } + iter_t _begin () const { return *thiz(); } + iter_t begin () const { return _begin (); } + iter_t _end () const { return thiz()->__end__ (); } + iter_t end () const { return _end (); } explicit operator bool () const { return thiz()->__more__ (); } unsigned len () const { return thiz()->__len__ (); } /* The following can only be enabled if item_t is reference type. Otherwise - * it will be returning pointer to temporary rvalue. - * TODO Use a wrapper return type to fix for non-reference type. */ + * it will be returning pointer to temporary rvalue. */ template <typename T = item_t, - hb_enable_if (hb_is_reference (T))> - hb_remove_reference<item_t>* operator -> () const { return hb_addressof (**thiz()); } + hb_enable_if (std::is_reference<T>::value)> + hb_remove_reference<item_t>* operator -> () const { return std::addressof (**thiz()); } item_t operator * () const { return thiz()->__item__ (); } item_t operator * () { return thiz()->__item__ (); } item_t operator [] (unsigned i) const { return thiz()->__item_at__ (i); } @@ -128,7 +120,9 @@ struct hb_iter_t #define HB_ITER_USING(Name) \ using item_t = typename Name::item_t; \ + using Name::_begin; \ using Name::begin; \ + using Name::_end; \ using Name::end; \ using Name::get_item_size; \ using Name::is_iterator; \ @@ -263,6 +257,8 @@ struct hb_is_iterator_of }; #define hb_is_iterator_of(Iter, Item) hb_is_iterator_of<Iter, Item>::value #define hb_is_iterator(Iter) hb_is_iterator_of (Iter, typename Iter::item_t) +#define hb_is_sorted_iterator_of(Iter, Item) (hb_is_iterator_of<Iter, Item>::value && Iter::is_sorted_iterator) +#define hb_is_sorted_iterator(Iter) hb_is_sorted_iterator_of (Iter, typename Iter::item_t) /* hb_is_iterable() */ @@ -289,7 +285,7 @@ struct hb_is_source_of { private: template <typename Iter2 = Iter, - hb_enable_if (hb_is_convertible (typename Iter2::item_t, hb_add_lvalue_reference<hb_add_const<Item>>))> + hb_enable_if (hb_is_convertible (typename Iter2::item_t, hb_add_lvalue_reference<const Item>))> static hb_true_type impl (hb_priority<2>); template <typename Iter2 = Iter> static auto impl (hb_priority<1>) -> decltype (hb_declval (Iter2) >> hb_declval (Item &), hb_true_type ()); @@ -385,7 +381,7 @@ struct hb_map_iter_t : void __forward__ (unsigned n) { it += n; } void __prev__ () { --it; } void __rewind__ (unsigned n) { it -= n; } - hb_map_iter_t __end__ () const { return hb_map_iter_t (it.end (), f); } + hb_map_iter_t __end__ () const { return hb_map_iter_t (it._end (), f); } bool operator != (const hb_map_iter_t& o) const { return it != o.it; } @@ -448,7 +444,7 @@ struct hb_filter_iter_t : bool __more__ () const { return bool (it); } void __next__ () { do ++it; while (it && !hb_has (p.get (), hb_get (f.get (), *it))); } void __prev__ () { do --it; while (it && !hb_has (p.get (), hb_get (f.get (), *it))); } - hb_filter_iter_t __end__ () const { return hb_filter_iter_t (it.end (), p, f); } + hb_filter_iter_t __end__ () const { return hb_filter_iter_t (it._end (), p, f); } bool operator != (const hb_filter_iter_t& o) const { return it != o.it; } @@ -561,7 +557,7 @@ struct hb_zip_iter_t : void __forward__ (unsigned n) { a += n; b += n; } void __prev__ () { --a; --b; } void __rewind__ (unsigned n) { a -= n; b -= n; } - hb_zip_iter_t __end__ () const { return hb_zip_iter_t (a.end (), b.end ()); } + hb_zip_iter_t __end__ () const { return hb_zip_iter_t (a._end (), b._end ()); } /* Note, we should stop if ANY of the iters reaches end. As such two compare * unequal if both items are unequal, NOT if either is unequal. */ bool operator != (const hb_zip_iter_t& o) const @@ -581,6 +577,91 @@ struct } HB_FUNCOBJ (hb_zip); +/* hb_concat() */ + +template <typename A, typename B> +struct hb_concat_iter_t : + hb_iter_t<hb_concat_iter_t<A, B>, typename A::item_t> +{ + hb_concat_iter_t () {} + hb_concat_iter_t (A& a, B& b) : a (a), b (b) {} + hb_concat_iter_t (const A& a, const B& b) : a (a), b (b) {} + + + typedef typename A::item_t __item_t__; + static constexpr bool is_random_access_iterator = + A::is_random_access_iterator && + B::is_random_access_iterator; + static constexpr bool is_sorted_iterator = false; + + __item_t__ __item__ () const + { + if (!a) + return *b; + return *a; + } + + __item_t__ __item_at__ (unsigned i) const + { + unsigned a_len = a.len (); + if (i < a_len) + return a[i]; + return b[i - a_len]; + } + + bool __more__ () const { return bool (a) || bool (b); } + + unsigned __len__ () const { return a.len () + b.len (); } + + void __next__ () + { + if (a) + ++a; + else + ++b; + } + + void __forward__ (unsigned n) + { + if (!n) return; + if (!is_random_access_iterator) { + while (n-- && *this) { + (*this)++; + } + return; + } + + unsigned a_len = a.len (); + if (n > a_len) { + n -= a_len; + a.__forward__ (a_len); + b.__forward__ (n); + } else { + a.__forward__ (n); + } + } + + hb_concat_iter_t __end__ () const { return hb_concat_iter_t (a._end (), b._end ()); } + bool operator != (const hb_concat_iter_t& o) const + { + return a != o.a + || b != o.b; + } + + private: + A a; + B b; +}; +struct +{ HB_PARTIALIZE(2); + template <typename A, typename B, + hb_requires (hb_is_iterable (A) && hb_is_iterable (B))> + hb_concat_iter_t<hb_iter_type<A>, hb_iter_type<B>> + operator () (A&& a, B&& b) const + { return hb_concat_iter_t<hb_iter_type<A>, hb_iter_type<B>> (hb_iter (a), hb_iter (b)); } +} +HB_FUNCOBJ (hb_concat); + /* hb_apply() */ template <typename Appl> |