C++ 如何将一对迭代器转换为视图？

我有一对迭代器，我想在上面使用

ranges:：views:：filter（some_谓词）

（使用管道操作符）。首先，我应该将迭代器对转换为视图。我曾尝试使用

ranges:：subrange（first，last）

来执行此操作，但收到了可怕的错误消息

注1：我使用的是C++14和range-v3版本0.9.1（最新版本与gcc-5.5兼容）。如果使用C++17/20和/或使用C++20 std:：ranges时解决方案不同，我还想知道发生了什么变化

注2：我发现range-v3严重不足，所以我使用了。如果你知道更好的文档，我很感兴趣

---

编辑：

在我的真实代码中，我包装了一个java风格的遗留迭代器（它有一个

next（）

方法，而不是

运算符+++

/

运算符*

。我将它们包装在一个与C++兼容的包装器中。然后我尝试将该包装器转换为一个视图，并最终对其进行筛选。我在上复制了一个最小的示例。按照建议使用

迭代器范围

，但它仍然无法编译（请参阅下面的第二次编辑）

#包括“range/v3/all.hpp”
#包括“range/v3/iterator_range.hpp”
类LegacyIteratorWrapper{
公众：
使用value_type=int；
使用差分类型=std:：ptrdiff\t；
使用指针=值_类型*；
使用引用=值\类型&；
使用迭代器_category=std:：input_iterator_标记；
//该类型不是默认可构造的，错误来自这里
LegacyIteratorWrapper（）=删除；
静态LegacyIteratorWrapper create（）；
参考运算符*（）常数；
指针运算符->（）；
LegacyIteratorWrapper&运算符++（）；
LegacyIteratorWrapper运算符++（int）；
friend bool运算符==（常量LegacyIteratorWrapper&a，常量LegacyIteratorWrapper&b）；
friend bool运算符！=（常量LegacyIteratorWrapper&a，常量LegacyIteratorWrapper&b）；
};
void foo（）
{
LegacyIteratorWrapper begin{LegacyIteratorWrapper:：create（）}；
LegacyIteratorWrapper end{LegacyIteratorWrapper:：create（）}；
范围：：迭代器_range rng{begin，end}；
自动
|范围：：视图：：过滤器(
[&]（自动{return true；}
)
;
}

在/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/functional/reference_wrapper.hpp:24:0中包含的文件中，
从/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/detail/variant.hpp:33，
从/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/iterator/common_iterator.hpp:26，
从/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/view/interface.hpp:24，
从/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/view/ref.hpp:25，
从/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/action/action.hpp:29，
从/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/action.hpp:17，
从/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/all.hpp:17，
发件人：1:
/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/functional/pipeable.hpp:在“constexpr auto ranges:：operator |（Arg&&，Pipe）”的实例化中[with Arg=ranges:：iterator_range&；Pipe=ranges:：views:：view；bool CPP_false=false；typename concepts:：detail:：identity:：invoke=0]：
：33:11：从这里开始需要
/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/functional/pipeable.hpp:63:53:错误：调用“ranges:：pipeable\u access:：impl:：pipe（ranges:：iterator\u range&，ranges:：views:：view&）”时没有匹配的函数
返回管道可访问：：impl：：管道（静态管道转换（arg），管道）；
^
在/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/range_fwd.hpp:22:0中包含的文件中，
从/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/action/action.hpp:21，
从/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/action.hpp:17，
从/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/all.hpp:17，
发件人：1:
/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/view/view.hpp:114:35：注：候选：模板静态constexpr自动范围：：视图：：视图：：管道（Rng&&，Vw&&，concepts：：detail：：enable_if________t）[带Rng=Rng；Vw=Vw；view=ranges ranges make_pipeable__fn:：operator（）（Fun）const[带Fun=ranges ranges detail:：detail:：bind_-back
静态constexpr自动CPP_fun（管道）（Rng和Rng、Vw和VV）（//
^
/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/view/view.hpp:114:35:注意：模板参数推断/替换失败：
：在函数“void foo（）”中：
：33:11:错误：“void”的类型不完整
)
^
ASM生成编译器返回：1
在/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/functional/reference_wrapper.hpp:24:0中包含的文件中，
从/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/detail/variant.hpp:33，
从/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/iterator/common_iterator.hpp:26，
从/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/view/interface.hpp:24，
从/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/view/ref.hpp:25，
从/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/action/action.hpp:29，
从/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/action.hpp:17，
从/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/all.hpp:17，
发件人：1:
/opt/compiler explorer/libs/rangesv3/0.9.1/include/range/v3/functional/pipeable.hpp:在“constexpr auto ranges:：operator |（Arg&，Pipe）”的实例化中[with Arg=ranges:：i]
In file included from /opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/functional/reference_wrapper.hpp:24:0,
                 from /opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/detail/variant.hpp:33,
                 from /opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/iterator/common_iterator.hpp:26,
                 from /opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/view/interface.hpp:24,
                 from /opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/view/ref.hpp:25,
                 from /opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/action/action.hpp:29,
                 from /opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/action.hpp:17,
                 from /opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/all.hpp:17,
                 from <source>:1:
/opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/functional/pipeable.hpp: In instantiation of 'constexpr auto ranges::operator|(Arg&&, Pipe) [with Arg = ranges::iterator_range<LegacyIteratorWrapper, LegacyIteratorWrapper>&; Pipe = ranges::views::view<ranges::make_pipeable_fn::operator()(Fun) const [with Fun = ranges::detail::bind_back_fn_<ranges::views::cpp20_filter_fn, foo()::<lambda(auto:15)> >]::_>; bool CPP_false_ = false; typename concepts::detail::identity<typename std::enable_if<(static_cast<bool>(((! is_pipeable_v<Arg>) && is_pipeable_v<Pipe>)) || CPP_false_), void>::type>::invoke<int> <anonymous> = 0]':
<source>:33:11:   required from here
/opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/functional/pipeable.hpp:63:53: error: no matching function for call to 'ranges::pipeable_access::impl<ranges::views::view<ranges::make_pipeable_fn::operator()(Fun) const [with Fun = ranges::detail::bind_back_fn_<ranges::views::cpp20_filter_fn, foo()::<lambda(auto:15)> >]::_> >::pipe(ranges::iterator_range<LegacyIteratorWrapper, LegacyIteratorWrapper>&, ranges::views::view<ranges::make_pipeable_fn::operator()(Fun) const [with Fun = ranges::detail::bind_back_fn_<ranges::views::cpp20_filter_fn, foo()::<lambda(auto:15)> >]::_>&)'
             return pipeable_access::impl<Pipe>::pipe(static_cast<Arg &&>(arg), pipe);
                                                     ^
In file included from /opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/range_fwd.hpp:22:0,
                 from /opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/action/action.hpp:21,
                 from /opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/action.hpp:17,
                 from /opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/all.hpp:17,
                 from <source>:1:
/opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/view/view.hpp:114:35: note: candidate: template<class Rng, class Vw> static constexpr auto ranges::views::view<View>::pipe(Rng&&, Vw&&, concepts::detail::enable_if_t<concepts::detail::Nil, (static_cast<bool>((viewable_range<Rng> && invocable<View&, Rng>)) || concepts::detail::CPP_false(concepts::detail::Nil{}))>) [with Rng = Rng; Vw = Vw; View = ranges::make_pipeable_fn::operator()(Fun) const [with Fun = ranges::detail::bind_back_fn_<ranges::views::cpp20_filter_fn, foo()::<lambda(auto:15)> >]::_]
             static constexpr auto CPP_fun(pipe)(Rng && rng, Vw && v)( //
                                   ^
/opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/view/view.hpp:114:35: note:   template argument deduction/substitution failed:
<source>: In function 'void foo()':
<source>:33:11: error: 'void _' has incomplete type
           )
           ^
ASM generation compiler returned: 1
In file included from /opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/functional/reference_wrapper.hpp:24:0,
                 from /opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/detail/variant.hpp:33,
                 from /opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/iterator/common_iterator.hpp:26,
                 from /opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/view/interface.hpp:24,
                 from /opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/view/ref.hpp:25,
                 from /opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/action/action.hpp:29,
                 from /opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/action.hpp:17,
                 from /opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/all.hpp:17,
                 from <source>:1:
/opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/functional/pipeable.hpp: In instantiation of 'constexpr auto ranges::operator|(Arg&&, Pipe) [with Arg = ranges::iterator_range<LegacyIteratorWrapper, LegacyIteratorWrapper>&; Pipe = ranges::views::view<ranges::make_pipeable_fn::operator()(Fun) const [with Fun = ranges::detail::bind_back_fn_<ranges::views::cpp20_filter_fn, foo()::<lambda(auto:15)> >]::_>; bool CPP_false_ = false; typename concepts::detail::identity<typename std::enable_if<(static_cast<bool>(((! is_pipeable_v<Arg>) && is_pipeable_v<Pipe>)) || CPP_false_), void>::type>::invoke<int> <anonymous> = 0]':
<source>:33:11:   required from here
/opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/functional/pipeable.hpp:63:53: error: no matching function for call to 'ranges::pipeable_access::impl<ranges::views::view<ranges::make_pipeable_fn::operator()(Fun) const [with Fun = ranges::detail::bind_back_fn_<ranges::views::cpp20_filter_fn, foo()::<lambda(auto:15)> >]::_> >::pipe(ranges::iterator_range<LegacyIteratorWrapper, LegacyIteratorWrapper>&, ranges::views::view<ranges::make_pipeable_fn::operator()(Fun) const [with Fun = ranges::detail::bind_back_fn_<ranges::views::cpp20_filter_fn, foo()::<lambda(auto:15)> >]::_>&)'
             return pipeable_access::impl<Pipe>::pipe(static_cast<Arg &&>(arg), pipe);
                                                     ^
In file included from /opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/range_fwd.hpp:22:0,
                 from /opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/action/action.hpp:21,
                 from /opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/action.hpp:17,
                 from /opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/all.hpp:17,
                 from <source>:1:
/opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/view/view.hpp:114:35: note: candidate: template<class Rng, class Vw> static constexpr auto ranges::views::view<View>::pipe(Rng&&, Vw&&, concepts::detail::enable_if_t<concepts::detail::Nil, (static_cast<bool>((viewable_range<Rng> && invocable<View&, Rng>)) || concepts::detail::CPP_false(concepts::detail::Nil{}))>) [with Rng = Rng; Vw = Vw; View = ranges::make_pipeable_fn::operator()(Fun) const [with Fun = ranges::detail::bind_back_fn_<ranges::views::cpp20_filter_fn, foo()::<lambda(auto:15)> >]::_]
             static constexpr auto CPP_fun(pipe)(Rng && rng, Vw && v)( //
                                   ^
/opt/compiler-explorer/libs/rangesv3/0.9.1/include/range/v3/view/view.hpp:114:35: note:   template argument deduction/substitution failed:
<source>: In function 'void foo()':
<source>:33:11: error: 'void _' has incomplete type
           )
           ^
Execution build compiler returned: 1

auto my_range = std::ranges::subrange{begi,endi};