Заменить диапазон прогнозируемых полей структуры ⇐ C++

[Anonymous]

У меня есть диапазон через многоуровневую структуру. < /p>
Поля могут быть доступны только через оператор []. Заменить на одну из этих полей. : Заменить () функция? Я использую C ++ 20, но мне также любопытно, если это можно сделать, используя C ++ 23, если это необходимо. < /P>
#include
#include
using namespace std;

enum Direction
{
HORIZONTAL,
VERTICAL
};

struct Maille
{
int16_t i, j;

int16_t& operator[](Direction input_direction)
{
switch (input_direction)
{
case HORIZONTAL:
return j;
case VERTICAL:
return i;
}
}
int16_t operator[](Direction input_direction) const
{
switch (input_direction)
{
case HORIZONTAL:
return j;
case VERTICAL:
return i;
}
}
};

int main()
{

Maille tab[2]={
{.i=1,.j=2},
{.i=2,.j=1}
};

for (Maille& m : tab)
{
if (m[HORIZONTAL]==1)
m[HORIZONTAL]=4;
}

ranges::replace(tab | views::transform([](Maille& m){
return m[HORIZONTAL];}),1,4);

return 0;
}
< /code>
Сообщение об ошибке: < /p>
main.cpp: In function ‘int main()’:
main.cpp:52:20: error: no match for call to ‘(const std::ranges::__replace_fn) (std::ranges::transform_view, main():: >, int, int)’
52 | ranges::replace(tab | views::transform([](Maille& m){
| ~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
53 | return m[HORIZONTAL];}),1,4);
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/14/algorithm:63,
from main.cpp:3:
/usr/include/c++/14/bits/ranges_algo.h:782:7: note: candidate: ‘template requires (input_iterator) && (sentinel_for) && ((indirectly_writable) && (indirect_binary_predicate::__type, const _Tp1*>)) constexpr _Iter std::ranges::__replace_fn::operator()(_Iter, _Sent, const _Tp1&, const _Tp2&, _Proj) const’
782 | operator()(_Iter __first, _Sent __last,
| ^~~~~~~~
/usr/include/c++/14/bits/ranges_algo.h:782:7: note: candidate expects 4 arguments, 3 provided
/usr/include/c++/14/bits/ranges_algo.h:799:7: note: candidate: ‘template requires (input_range) && ((indirectly_writable)())), const _Tp2&>) && (indirect_binary_predicate)())), _Proj>::__type, const _Tp1*>)) constexpr std::ranges::borrowed_iterator_t std::ranges::__replace_fn::operator()(_Range&&, const _Tp1&, const _Tp2&, _Proj) const’
799 | operator()(_Range&& __r,
| ^~~~~~~~
/usr/include/c++/14/bits/ranges_algo.h:799:7: note: template argument deduction/substitution failed:
/usr/include/c++/14/bits/ranges_algo.h:799:7: note: constraints not satisfied
In file included from /usr/include/c++/14/bits/stl_iterator_base_types.h:71,
from /usr/include/c++/14/iterator:61,
from /usr/include/c++/14/ranges:43,
from main.cpp:2:
/usr/include/c++/14/bits/iterator_concepts.h: In substitution of ‘template requires (input_range) && ((indirectly_writable) && (indirect_binary_predicate)) constexpr std::ranges::borrowed_iterator_t std::ranges::__replace_fn::operator()(_Range&&, const _Tp1&, const _Tp2&, _Proj) const [with _Range = std::ranges::transform_view; _Tp1 = int; _Tp2 = int; _Proj = std::identity]’:
main.cpp:52:20: required from here
52 | ranges::replace(tab | views::transform([](Maille& m){
| ~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
53 | return m[HORIZONTAL];}),1,4);
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/iterator_concepts.h:561:13: required for the satisfaction of ‘indirectly_writable’ [with _Range = std::ranges::transform_view; _Tp2 = int]
/usr/include/c++/14/bits/iterator_concepts.h:561:35: in requirements with ‘_Out&& __o’, ‘_Tp&& __t’ [with _Out = std::ranges::transform_view::_Iterator; _Tp = const int&]
/usr/include/c++/14/bits/iterator_concepts.h:563:14: note: the required expression ‘*__o =(forward)(__t)’ is invalid
563 | *__o = std::forward(__t);
| ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/iterator_concepts.h:564:34: note: the required expression ‘*(forward)(__o)=(forward)(__t)’ is invalid
564 | *std::forward(__o) = std::forward(__t);
| ~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/iterator_concepts.h:566:11: note: the required expression ‘const_cast)())&&>(*__o) =(forward)(__t)’ is invalid
565 | const_cast(*__o)
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
566 | = std::forward(__t);
| ^~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/iterator_concepts.h:568:11: note: the required expression ‘const_cast)())&&>(*(forward)(__o))=(forward)(__t)’ is invalid
567 | const_cast(*std::forward(__o))
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
568 | = std::forward(__t);
| ^~~~~~~~~~~~~~~~~~~~~~~~
cc1plus: note: set ‘-fconcepts-diagnostics-depth=’ to at least 2 for more detail
main.cpp: In member function ‘int16_t& Maille::operator[](Direction)’:
main.cpp:25:9: warning: control reaches end of non-void function [-Wreturn-type]
25 | }
| ^


Подробнее здесь: https://stackoverflow.com/questions/794 ... uct-fields