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LibJS: Use a Variant instead of two Optionals for ThrowCompletionOr

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Comes with the usual benefit of saving some space on the stack, as well
as making a situation where both or neither Optionals hold a value
impossible.

The various unwrapping additions are required as we can no longer
construct a ThrowCompletionOr<T> from an Optional<T> - rightfully so.
This commit is contained in:
Linus Groh 2023-03-01 14:52:31 +00:00
parent e77503e49b
commit 8f1d13e73b
6 changed files with 26 additions and 27 deletions
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31
Userland/Libraries/LibJS/Runtime/Completion.h
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@ -274,23 +274,23 @@ class [[nodiscard]] ThrowCompletionOr {
public:
ThrowCompletionOr()
requires(IsSame<ValueType, Empty>)
: m_value(Empty {})
: m_value_or_throw_completion(Empty {})
{
}
// Not `explicit` on purpose so that `return vm.throw_completion<Error>(...);` is possible.
ThrowCompletionOr(Completion throw_completion)
: m_throw_completion(move(throw_completion))
: m_value_or_throw_completion(move(throw_completion))
{
VERIFY(m_throw_completion->is_error());
VERIFY(m_value_or_throw_completion.template get<Completion>().is_error());
}
// Not `explicit` on purpose so that `return value;` is possible.
ThrowCompletionOr(ValueType value)
: m_value(move(value))
: m_value_or_throw_completion(move(value))
{
if constexpr (IsSame<ValueType, Value>)
VERIFY(!m_value->is_empty());
VERIFY(!m_value_or_throw_completion.template get<ValueType>().is_empty());
}
ThrowCompletionOr(ThrowCompletionOr const&) = default;
@ -299,7 +299,7 @@ public:
ThrowCompletionOr& operator=(ThrowCompletionOr&&) = default;
ThrowCompletionOr(OptionalNone value)
: m_value(ValueType { value })
: m_value_or_throw_completion(ValueType { value })
{
}
@ -309,28 +309,28 @@ public:
template<typename WrappedValueType>
ThrowCompletionOr(WrappedValueType const& value)
requires(!IsPOD<ValueType>)
: m_value(value)
: m_value_or_throw_completion(ValueType { value })
{
}
[[nodiscard]] bool is_throw_completion() const { return m_throw_completion.has_value(); }
Completion const& throw_completion() const { return *m_throw_completion; }
[[nodiscard]] bool is_throw_completion() const { return m_value_or_throw_completion.template has<Completion>(); }
Completion const& throw_completion() const { return m_value_or_throw_completion.template get<Completion>(); }
[[nodiscard]] bool has_value() const
requires(!IsSame<ValueType, Empty>)
{
return m_value.has_value();
return m_value_or_throw_completion.template has<ValueType>();
}
[[nodiscard]] ValueType const& value() const
requires(!IsSame<ValueType, Empty>)
{
return *m_value;
return m_value_or_throw_completion.template get<ValueType>();
}
// These are for compatibility with the TRY() macro in AK.
[[nodiscard]] bool is_error() const { return m_throw_completion.has_value(); }
[[nodiscard]] ValueType release_value() { return m_value.release_value(); }
Completion release_error() { return m_throw_completion.release_value(); }
[[nodiscard]] bool is_error() const { return m_value_or_throw_completion.template has<Completion>(); }
[[nodiscard]] ValueType release_value() { return move(m_value_or_throw_completion.template get<ValueType>()); }
Completion release_error() { return move(m_value_or_throw_completion.template get<Completion>()); }
ValueType release_allocated_value_but_fixme_should_propagate_errors()
{
@ -339,8 +339,7 @@ public:
}
private:
Optional<Completion> m_throw_completion;
Optional<ValueType> m_value;
Variant<ValueType, Completion> m_value_or_throw_completion;
};
template<>