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[iter] Split hb_iter_t<> into hb_iter_t<> and hb_iter_mixin_t<>

This commit is contained in:
Behdad Esfahbod 2018-12-21 18:09:45 -05:00
parent 865deeb3be
commit 2fc1860a5b
2 changed files with 21 additions and 12 deletions
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31
src/hb-iter.hh
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@ -49,9 +49,11 @@ struct hb_iter_t
typedef iter_t const_iter_t;
typedef Item item_t;
/* https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern */
private:
/* https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern */
const iter_t* thiz () const { return static_cast<const iter_t *> (this); }
iter_t* thiz () { return static_cast< iter_t *> (this); }
public:
/* Operators. */
operator iter_t () { return iter(); }
@ -80,9 +82,21 @@ struct hb_iter_t
unsigned len () const { return thiz()->__len__ (); }
bool random_access () const { return thiz()->__random_access__ (); }
/*
* Subclasses overrides:
*/
protected:
hb_iter_t () {}
hb_iter_t (const hb_iter_t &o) {}
void operator = (const hb_iter_t &o) {}
};
/* Mixin to fill in what the subclass doesn't provide. */
template <typename iter_t, typename item_t = typename iter_t::__item_type__>
struct hb_iter_mixin_t
{
private:
/* https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern */
const iter_t* thiz () const { return static_cast<const iter_t *> (this); }
iter_t* thiz () { return static_cast< iter_t *> (this); }
public:
/* Access: Implement __item__(), or __item_at__() if random-access. */
item_t& __item__ () const { return thiz()->item_at (0); }
@ -94,11 +108,11 @@ struct hb_iter_t
/* Advancing: Implement __next__(), or __forward__() if random-access. */
void __next__ () { thiz()->forward (1); }
void __forward__ (unsigned n) { while (n--) next (); }
void __forward__ (unsigned n) { while (n--) thiz()->next (); }
/* Rewinding: Implement __prev__() or __rewind__() if bidirectional. */
void __prev__ () { thiz()->rewind (1); }
void __rewind__ (unsigned n) { while (n--) prev (); }
void __rewind__ (unsigned n) { while (n--) thiz()->prev (); }
/* Population: Implement __len__() if known. */
unsigned __len__ () const
@ -106,11 +120,6 @@ struct hb_iter_t
/* Random access: Return true if len(), forward(), item_at() are fast. */
bool __random_access__ () const { return false; }
protected:
hb_iter_t () {}
hb_iter_t (const hb_iter_t &o) {}
void operator = (const hb_iter_t &o) {}
};

2
src/test-iter.cc
View File

@ -30,7 +30,7 @@
#include "hb-array.hh"
template <typename T>
struct array_iter_t : hb_iter_t<array_iter_t<T>, T>
struct array_iter_t : hb_iter_t<array_iter_t<T>, T>, hb_iter_mixin_t<array_iter_t<T>, T>
{
array_iter_t (hb_array_t<T> arr_) : arr (arr_) {}