147dd52f7d
Any integer type can convert to match this signature, but the diagnostic will only report that this deleted function was matched. Switch to a template function so that the diagnostic can report the unconverted integer type.
76 lines
2.6 KiB
C++
76 lines
2.6 KiB
C++
/*
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* This file is part of the DXX-Rebirth project <https://www.dxx-rebirth.com/>.
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* It is copyright by its individual contributors, as recorded in the
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* project's Git history. See COPYING.txt at the top level for license
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* terms and a link to the Git history.
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*/
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#pragma once
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#include "dxxsconf.h"
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#include <array>
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#include "fwd-d_array.h"
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namespace dcx {
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/* Wrap a std::array and override the normal indexing operations to take
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* an instance of type `E`. This is intended for use where `E` is an
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* instance of `enum class`. When `E` is an `enum class`, instances of
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* `E` cannot implicitly convert to `std::array::size_type`, and so
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* would require a cast in the caller if this wrapper were not used.
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* Using this wrapper moves the casts into the wrapper, after the
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* compiler has checked that the argument is the right type of `enum
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* class`. This prevents accidentally using an incorrect `enum class`.
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*
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* Other types for E are not likely to be useful, but are not blocked.
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*/
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template <typename T, std::size_t N, typename E>
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/* `std::size_t` is `unsigned` on i686-w64-mingw32, and `unsigned long` on
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* x86_64-pc-linux-gnu.
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*
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* As a result, if `E` is `unsigned`, then i686-w64-mingw32 breaks due to
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* `operator[](E)` and `operator[](std::size_t)` being the same signature. If
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* `E` is `unsigned long`, then x86_64-pc-linux-gnu breaks for the same reason.
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* Disallow both `unsigned` and `unsigned long`, so that any attempt to use
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* either for `E` will break everywhere, rather than breaking only some
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* platforms.
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*/
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requires(!std::is_same<unsigned, E>::value && !std::is_same<unsigned long, E>::value)
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struct enumerated_array : std::array<T, N>
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{
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using base_type = std::array<T, N>;
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using index_type = E;
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using typename base_type::reference;
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using typename base_type::const_reference;
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constexpr reference at(E position)
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{
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return this->base_type::at(static_cast<std::size_t>(position));
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}
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constexpr const_reference at(E position) const
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{
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return this->base_type::at(static_cast<std::size_t>(position));
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}
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constexpr reference operator[](E position)
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{
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return this->base_type::operator[](static_cast<std::size_t>(position));
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}
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constexpr const_reference operator[](E position) const
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{
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return this->base_type::operator[](static_cast<std::size_t>(position));
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}
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template <typename I>
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requires(std::is_integral_v<I>)
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const_reference operator[](I) const = delete;
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[[nodiscard]]
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static constexpr bool valid_index(std::size_t s)
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{
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return s < N;
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}
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[[nodiscard]]
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static constexpr bool valid_index(E e)
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{
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return valid_index(static_cast<std::size_t>(e));
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}
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};
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}
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