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Address all comments from Johannes' review
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,25 +1,23 @@ | ||
| // Copyright 2022, University of Freiburg, | ||
| // Chair of Algorithms and Data Structures. | ||
| // Author: | ||
| // 2022 - Johannes Kalmbach <[email protected]> | ||
| // Copyright 2022 - 2024, University of Freiburg | ||
| // Chair of Algorithms and Data Structures | ||
| // Author: Johannes Kalmbach <[email protected]> | ||
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| #ifndef QLEVER_TRANSPARENTFUNCTORS_H | ||
| #define QLEVER_TRANSPARENTFUNCTORS_H | ||
| #pragma once | ||
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| #include <util/Forward.h> | ||
| #include <util/TypeTraits.h> | ||
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| #include <utility> | ||
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| /// Contains several function object types with templated operator() that wrap | ||
| /// overloaded functions from the standard library. This enables passing them as | ||
| /// function parameters. | ||
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| /// Note that in theory all of them could be implemented shorter as captureless | ||
| /// lambda expressions. We have chosen not to do this because the STL also does | ||
| /// not choose this approach (see e.g. `std::less`, `std::plus`, etc.) and | ||
| /// because global inline lambdas in header files might in theory cause ODR (one | ||
| /// definition rule) problems, especially when using different compilers. | ||
| // Contains several function object types with templated operator() that wrap | ||
| // overloaded functions from the standard library. This enables passing them as | ||
| // function parameters. | ||
| // | ||
| // NOTE: in theory all of them could be implemented shorter as captureless | ||
| // lambda expressions. We have chosen not to do this because the STL also does | ||
| // not choose this approach (see e.g. `std::less`, `std::plus`, etc.) and | ||
| // because global inline lambdas in header files might in theory cause ODR (one | ||
| // definition rule) problems, especially when using different compilers. | ||
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| namespace ad_utility { | ||
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@@ -79,37 +77,60 @@ struct ToBoolImpl { | |
| } | ||
| }; | ||
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| // Implementation of `staticCast` (see below). | ||
| template <typename T> | ||
| struct StaticCastImpl { | ||
| constexpr decltype(auto) operator()(auto&& x) const { | ||
| return static_cast<T>(AD_FWD(x)); | ||
| } | ||
| }; | ||
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| // Implementation of `dereference` (see below). | ||
| struct DereferenceImpl { | ||
| constexpr decltype(auto) operator()(auto&& x) const { return *AD_FWD(x); } | ||
| }; | ||
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| } // namespace detail | ||
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| /// Return the first element via perfect forwarding of any type for which | ||
| /// `std::get<0>(x)` is valid. This holds e.g. for `std::pair`, `std::tuple`, | ||
| /// and `std::array`. | ||
| // Return the first element via perfect forwarding of any type for which | ||
| // `std::get<0>(x)` is valid. This holds e.g. for `std::pair`, `std::tuple`, | ||
| // and `std::array`. | ||
| static constexpr detail::FirstImpl first; | ||
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| /// Return the second element via perfect forwarding of any type for which | ||
| /// `std::get<1>(x)` is valid. This holds e.g. for `std::pair`, `std::tuple`, | ||
| /// and `std::array`. | ||
| // Return the second element via perfect forwarding of any type for which | ||
| // `std::get<1>(x)` is valid. This holds e.g. for `std::pair`, `std::tuple`, | ||
| // and `std::array`. | ||
| static constexpr detail::SecondImpl second; | ||
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| /// Transparent functor for `std::holds_alternative` | ||
| // Transparent functor for `std::holds_alternative` | ||
| template <typename T> | ||
| static constexpr detail::HoldsAlternativeImpl<T> holdsAlternative; | ||
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| /// Transparent functor for `std::get`. Currently only works for `std::variant` | ||
| /// and not for `std::array` or `std::tuple`. | ||
| // Transparent functor for `std::get`. Currently only works for `std::variant` | ||
| // and not for `std::array` or `std::tuple`. | ||
| template <typename T> | ||
| static constexpr detail::GetImpl<T> get; | ||
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| /// Transparent functor for `std::get_if`. As an extension to `std::get_if`, | ||
| /// `ad_utility::getIf` may also be called with a `variant` object or reference, | ||
| /// not only with a pointer. | ||
| // Transparent functor for `std::get_if`. As an extension to `std::get_if`, | ||
| // `ad_utility::getIf` may also be called with a `variant` object or reference, | ||
| // not only with a pointer. | ||
| template <typename T> | ||
| static constexpr detail::GetIfImpl<T> getIf; | ||
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| // Transparent functor that converts any type to `bool` via | ||
| // `static_cast<bool>`. | ||
| static constexpr detail::ToBoolImpl toBool; | ||
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| /// A functor that takes an arbitrary number of arguments by reference and does | ||
| /// nothing. | ||
| // Transparent functor that casts any type to `T` via `static_cast<T>`. | ||
| template <typename T> | ||
| static constexpr detail::StaticCastImpl<T> staticCast{}; | ||
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| // Transparent functor that dereferences a pointer or smart pointer. | ||
| static constexpr detail::DereferenceImpl dereference; | ||
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| // Transparent functor that takes an arbitrary number of arguments by reference | ||
| // and does nothing. We also use the type `Noop`, hence it is defined here and | ||
| // not in the `detail` namespace above. | ||
| struct Noop { | ||
| void operator()(const auto&...) const { | ||
| // This function deliberately does nothing (static analysis expects a | ||
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@@ -118,16 +139,4 @@ struct Noop { | |
| }; | ||
| [[maybe_unused]] static constexpr Noop noop{}; | ||
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| template <typename T> | ||
| struct StaticCast { | ||
| constexpr decltype(auto) operator()(auto&& x) const { | ||
| return static_cast<T>(AD_FWD(x)); | ||
| } | ||
| }; | ||
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| template <typename T> | ||
| static constexpr StaticCast<T> staticCast{}; | ||
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| } // namespace ad_utility | ||
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| #endif // QLEVER_TRANSPARENTFUNCTORS_H | ||