mirror of
https://github.com/mutouyun/cpp-ipc.git
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99 lines
2.4 KiB
C++
99 lines
2.4 KiB
C++
/**
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* \file libimp/dataof.h
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* \author mutouyun (orz@orzz.org)
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* \brief Returns the data pointer of the given range.
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* \date 2023-05-27
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*/
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#pragma once
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#include <type_traits> // std::declval, std::true_type, std::false_type
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#include <cstddef> // std::size_t
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#include "libimp/def.h"
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#include "libimp/generic.h"
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LIBIMP_NAMESPACE_BEG_
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/**
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* \see https://en.cppreference.com/w/cpp/iterator/data
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*/
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namespace detail_dataof {
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template <typename T>
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struct trait_has_data {
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private:
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template <typename Type>
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static std::true_type check(decltype(std::declval<Type>().data())*);
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template <typename Type>
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static std::false_type check(...);
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public:
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using type = decltype(check<T>(nullptr));
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static constexpr auto value = type::value;
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};
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template <typename T>
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struct trait_has_Data {
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private:
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template <typename Type>
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static std::true_type check(decltype(std::declval<Type>().Data())*);
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template <typename Type>
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static std::false_type check(...);
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public:
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using type = decltype(check<T>(nullptr));
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static constexpr auto value = type::value;
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};
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template <typename C, bool = trait_has_data<C>::value
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, bool = trait_has_Data<C>::value>
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struct trait;
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template <typename T, std::size_t N>
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struct trait<T[N], false, false> {
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static constexpr T const *dataof(T const (&arr)[N]) noexcept {
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return arr;
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}
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static constexpr T *dataof(T (&arr)[N]) noexcept {
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return arr;
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}
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};
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template <typename C, bool B>
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struct trait<C, true, B> {
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template <typename T>
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static constexpr auto dataof(T &&c) noexcept(noexcept(c.data())) {
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return std::forward<T>(c).data();
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}
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};
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template <typename C>
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struct trait<C, false, true> {
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template <typename T>
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static constexpr auto dataof(T &&c) noexcept(noexcept(c.Data())) {
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return std::forward<T>(c).Data();
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}
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};
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template <typename C>
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struct trait<C, false, false> {
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template <typename T>
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static constexpr T const *dataof(std::initializer_list<T> il) noexcept {
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return il.begin();
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}
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template <typename T>
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static constexpr T const *dataof(T const *p) noexcept {
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return p;
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}
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};
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} // namespace detail_dataof
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template <typename C,
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typename T = detail_dataof::trait<std::remove_cv_t<std::remove_reference_t<C>>>,
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typename R = decltype(T::dataof(std::declval<C>()))>
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constexpr R dataof(C &&c) noexcept(noexcept(T::dataof(std::forward<C>(c)))) {
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return T::dataof(std::forward<C>(c));
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}
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LIBIMP_NAMESPACE_END_
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