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[iter] Clarify readonly vs lvalue iterators 

lvalue iterators must declare __item_type__ as a reference.
This commit is contained in:
Behdad Esfahbod 2018-12-27 17:17:28 -05:00
parent 2cbf5bf3a9
commit 5ec11ce13a
4 changed files with 16 additions and 13 deletions
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6
src/hb-array.hh
View File

@ -38,8 +38,8 @@ struct hb_sorted_array_t;
template <typename Type>
struct hb_array_t :
hb_iter_t<hb_array_t<Type>, Type>,
hb_iter_mixin_t<hb_array_t<Type>, Type>
hb_iter_t<hb_array_t<Type>, Type&>,
hb_iter_mixin_t<hb_array_t<Type>, Type&>
{
/*
* Constructors.
@ -52,7 +52,7 @@ struct hb_array_t :
/*
* Iterator implementation.
*/
typedef Type __item_type__;
typedef Type& __item_type__;
Type& __item_at__ (unsigned i) const
{
if (unlikely (i >= length)) return CrapOrNull (Type);

11
src/hb-iter.hh
View File

@ -60,9 +60,10 @@ struct hb_iter_t
iter_t iter () const { return *thiz(); }
explicit_operator bool () const { return thiz()->__more__ (); }
unsigned len () const { return thiz()->__len__ (); }
item_t* operator -> () const { return hb_addressof (*thiz()); }
item_t& operator * () const { return thiz()->__item__ (); }
item_t& operator [] (unsigned i) const { return thiz()->__item_at__ (i); }
/* TODO enable_if item_t is reference type only. */
typename hb_remove_reference (item_t)* operator -> () const { return hb_addressof (*thiz()); }
item_t operator * () const { return thiz()->__item__ (); }
item_t operator [] (unsigned i) const { return thiz()->__item_at__ (i); }
iter_t& operator += (unsigned count) { thiz()->__forward__ (count); return *thiz(); }
iter_t& operator ++ () { thiz()->__next__ (); return *thiz(); }
iter_t& operator -= (unsigned count) { thiz()->__rewind__ (count); return *thiz(); }
@ -120,8 +121,8 @@ struct hb_iter_mixin_t
public:
/* Access: Implement __item__(), or __item_at__() if random-access. */
item_t& __item__ () const { return (*thiz())[0]; }
item_t& __item_at__ (unsigned i) const { return *(*thiz() + i); }
item_t __item__ () const { return (*thiz())[0]; }
item_t __item_at__ (unsigned i) const { return *(*thiz() + i); }
/* Termination: Implement __more__(), or __len__() if random-access. */
bool __more__ () const { return thiz()->len (); }

6
src/hb-set.hh
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@ -672,14 +672,14 @@ struct hb_set_t
* Iterator implementation.
*/
struct iter_t :
hb_sorted_iter_t<iter_t, const hb_codepoint_t>,
hb_iter_mixin_t<iter_t, const hb_codepoint_t>
hb_sorted_iter_t<iter_t, hb_codepoint_t>,
hb_iter_mixin_t<iter_t, hb_codepoint_t>
{
iter_t (const hb_set_t &s_ = Null(hb_set_t)) :
s (&s_), v (INVALID), l (s->get_population () + 1) { __next__ (); }
typedef hb_codepoint_t __item_type__;
const hb_codepoint_t& __item__ () const { return v; }
hb_codepoint_t __item__ () const { return v; }
bool __more__ () const { return v != INVALID; }
void __next__ () { s->next (&v); if (l) l--; }
void __prev__ () { s->previous (&v); }

6
src/test-iter.cc
View File

@ -33,11 +33,13 @@
template <typename T>
struct array_iter_t : hb_iter_t<array_iter_t<T>, T>, hb_iter_mixin_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_) {}
typedef T __item_type__;
typedef T& __item_type__;
T& __item_at__ (unsigned i) const { return arr[i]; }
void __forward__ (unsigned n) { arr += n; }
void __rewind__ (unsigned n) { arr -= n; }