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Rotate menu items in terms of ranges, not indexes

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Kp 2020-09-11 03:08:02 +00:00
parent 495e808f7b
commit e2204cc8e5
1 changed files with 31 additions and 16 deletions
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47
similar/main/newmenu.cpp
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@ -555,26 +555,33 @@ static void swap_menu_item_entries(newmenu_item &a, newmenu_item &b)
swap(a.value, b.value);
}
template <typename T>
static void move_menu_item_entry(T &&t, newmenu_item *const items, uint_fast32_t citem, uint_fast32_t boundary)
template <typename F>
static inline void rotate_menu_item_subrange(F &&step_function, newmenu_item *const range_begin, const std::size_t start_index, const newmenu_item *const subrange_stop)
{
if (citem == boundary)
/* If citem == boundary, then this function is an elaborate
const auto subrange_start = std::next(range_begin, start_index);
/* The terminating pointer is named `subrange_stop`, rather than `end`,
* because traditional semantics hold that `end` cannot be
* dereferenced. In this function, the terminating pointer points
* to the last element that is legal to dereference, rather than the
* first element that is not legal.
*/
auto iter = subrange_start;
if (iter == subrange_stop)
/* If iter == subrange_stop, then this function is an elaborate
* no-op. Return immediately if there is no work to do.
*/
return;
auto a = &items[citem];
auto selected = std::make_pair(a->text, a->value);
for (; citem != boundary;)
auto &&selected = std::pair(iter->text, iter->value);
for (; iter != subrange_stop;)
{
citem = t(citem, 1);
auto &b = items[citem];
a->text = b.text;
a->value = b.value;
a = &b;
auto &a = *iter;
iter = step_function(iter, 1);
auto &b = *iter;
a.text = b.text;
a.value = b.value;
}
a->text = selected.first;
a->value = selected.second;
iter->text = selected.first;
iter->value = selected.second;
}
static int newmenu_save_selection_key(newmenu *menu, const d_event &event)
@ -599,10 +606,18 @@ static int newmenu_save_selection_key(newmenu *menu, const d_event &event)
}
break;
case KEY_PAGEUP + KEY_SHIFTED:
move_menu_item_entry(std::minus<uint_fast32_t>(), menu->items, menu->citem, 0);
{
const auto begin = menu->items;
const auto stop = begin;
rotate_menu_item_subrange(std::minus<void>(), begin, menu->citem, stop);
}
break;
case KEY_PAGEDOWN + KEY_SHIFTED:
move_menu_item_entry(std::plus<uint_fast32_t>(), menu->items, menu->citem, menu->nitems - 1);
{
const auto begin = menu->items;
const auto stop = std::next(begin, menu->nitems - 1);
rotate_menu_item_subrange(std::plus<void>(), begin, menu->citem, stop);
}
break;
}
return 0;