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Improve move semantics in Expected #4326

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merged 2 commits into from
Nov 28, 2022
Merged

Improve move semantics in Expected #4326

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a9d8898
Improve move semantics in Expected:
seelabs Oct 19, 2022
4b288aa
Replace enable_if with concepts in Expected
seelabs Oct 19, 2022
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26 changes: 14 additions & 12 deletions src/ripple/basics/Expected.h
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Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,10 @@
#define RIPPLE_BASICS_EXPECTED_H_INCLUDED

#include <ripple/basics/contract.h>

#include <boost/outcome.hpp>

#include <concepts>
#include <stdexcept>
#include <type_traits>

Expand Down Expand Up @@ -132,17 +135,16 @@ class [[nodiscard]] Expected
using Base = boost::outcome_v2::result<T, E, detail::throw_policy>;

public:
template <
typename U,
typename = std::enable_if_t<std::is_convertible_v<U, T>>>
constexpr Expected(U r) : Base(T{std::forward<U>(r)})
template <typename U>
requires std::convertible_to<U, T> constexpr Expected(U && r)
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Huh. We really need to tune up clang-format for requires clauses. I think this would read way better as...

    template <typename U>
    requires std::convertible_to<U, T>
    constexpr Expected(U&& r)
        : Base(T{std::forward<U>(r)})
    {
    }

But we need to get a few test cases into the code base before we clean that up. Carry on...

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This is because we use clang 10 for formatting. When I use clang 15 is formats in a reasonable way. I hope we can update our clang format shortly. I also don't mind delaying this patch until after we update formatting.

: Base(T{std::forward<U>(r)})
{
}

template <
typename U,
typename = std::enable_if_t<std::is_convertible_v<U, E>>>
constexpr Expected(Unexpected<U> e) : Base(E{std::forward<U>(e.value())})
template <typename U>
requires std::convertible_to<U, E> &&
(!std::is_reference_v<U>)constexpr Expected(Unexpected<U> e)
: Base(E{std::move(e.value())})
{
}

Expand Down Expand Up @@ -215,10 +217,10 @@ class [[nodiscard]] Expected<void, E>
{
}

template <
typename U,
typename = std::enable_if_t<std::is_convertible_v<U, E>>>
constexpr Expected(Unexpected<U> e) : Base(E{std::forward<U>(e.value())})
template <typename U>
requires std::convertible_to<U, E> &&
(!std::is_reference_v<U>)constexpr Expected(Unexpected<U> e)
: Base(E{std::move(e.value())})
{
}

Expand Down