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/*
* Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2021, Linus Groh <linusg@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/FlyString.h>
#include <AK/Optional.h>
#include <AK/Try.h>
#include <AK/Variant.h>
#include <LibJS/Runtime/Value.h>
namespace JS {
// Temporary helper akin to TRY(), but returning a default-constructed type (e.g. empty JS::Value)
// instead of the throw completion record. Use this as the bridge between functions that have
// already been updated to use completions and functions that haven't.
#define TRY_OR_DISCARD(expression) \
({ \
auto _temporary_result = (expression); \
if (_temporary_result.is_error()) \
return {}; \
_temporary_result.release_value(); \
})
// MUST() is to the spec's `!` what TRY() is to `?`.
// https://tc39.es/ecma262/#sec-returnifabrupt-shorthands
#define MUST(expression) \
({ \
auto _temporary_result = (expression); \
VERIFY(!_temporary_result.is_error()); \
/* The return value of "! Something()" is commonly */ \
/* ignored, so we assign to a temporary variable here */ \
/* to avoid having to (void) all the things. */ \
auto _temporary_value = _temporary_result.release_value(); \
move(_temporary_value); \
})
// 6.2.3 The Completion Record Specification Type, https://tc39.es/ecma262/#sec-completion-record-specification-type
class [[nodiscard]] Completion {
public:
enum class Type {
Normal,
Break,
Continue,
Return,
Throw,
};
Completion(Type type, Optional<Value> value, Optional<FlyString> target)
: m_type(type)
, m_value(move(value))
, m_target(move(target))
{
if (m_value.has_value())
VERIFY(!m_value->is_empty());
}
// 5.2.3.1 Implicit Completion Values, https://tc39.es/ecma262/#sec-implicit-completion-values
// Not `explicit` on purpose.
Completion(Value value)
: Completion(Type::Normal, value, {})
{
}
Completion()
: Completion(js_undefined())
{
}
[[nodiscard]] Type type() const { return m_type; }
[[nodiscard]] bool has_value() const { return m_value.has_value(); }
[[nodiscard]] Value value() const { return *m_value; }
[[nodiscard]] bool has_target() const { return m_target.has_value(); }
[[nodiscard]] FlyString const& target() const { return *m_target; }
// "abrupt completion refers to any completion with a [[Type]] value other than normal"
[[nodiscard]] bool is_abrupt() const { return m_type != Type::Normal; }
// These are for compatibility with the TRY() macro in AK.
[[nodiscard]] bool is_error() const { return m_type == Type::Throw; }
[[nodiscard]] Value release_value() { return m_value.release_value(); }
Completion release_error()
{
VERIFY(is_error());
return { m_type, release_value(), move(m_target) };
}
// 6.2.3.4 UpdateEmpty ( completionRecord, value ), https://tc39.es/ecma262/#sec-updateempty
Completion update_empty(Value value) const
{
// 1. Assert: If completionRecord.[[Type]] is either return or throw, then completionRecord.[[Value]] is not empty.
if (m_type == Type::Return || m_type == Type::Throw)
VERIFY(m_value.has_value());
// 2. If completionRecord.[[Value]] is not empty, return Completion(completionRecord).
if (m_value.has_value())
return *this;
// 3. Return Completion { [[Type]]: completionRecord.[[Type]], [[Value]]: value, [[Target]]: completionRecord.[[Target]] }.
return { m_type, value, m_target };
}
private:
Type m_type { Type::Normal }; // [[Type]]
Optional<Value> m_value; // [[Value]]
Optional<FlyString> m_target; // [[Target]]
};
template<typename ValueType>
class [[nodiscard]] ThrowCompletionOr {
public:
ThrowCompletionOr() requires(IsSame<ValueType, Empty>)
: m_value(Empty {})
{
}
// Not `explicit` on purpose so that `return vm.throw_completion<Error>(...);` is possible.
ThrowCompletionOr(Completion throw_completion)
: m_throw_completion(move(throw_completion))
{
VERIFY(throw_completion.is_error());
}
// Not `explicit` on purpose so that `return value;` is possible.
ThrowCompletionOr(ValueType value)
: m_value(move(value))
{
if constexpr (IsSame<ValueType, Value>)
VERIFY(!value.is_empty());
}
[[nodiscard]] bool is_throw_completion() const { return m_throw_completion.has_value(); }
Completion const& throw_completion() const { return *m_throw_completion; }
[[nodiscard]] bool has_value() const requires(!IsSame<ValueType, Empty>) { return m_value.has_value(); }
[[nodiscard]] ValueType const& value() const requires(!IsSame<ValueType, Empty>) { return *m_value; }
// 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(); }
private:
Optional<Completion> m_throw_completion;
Optional<ValueType> m_value;
};
template<>
class ThrowCompletionOr<void> : public ThrowCompletionOr<Empty> {
public:
using ThrowCompletionOr<Empty>::ThrowCompletionOr;
};
// 6.2.3.2 NormalCompletion ( value ), https://tc39.es/ecma262/#sec-normalcompletion
inline Completion normal_completion(Value value)
{
return { Completion::Type::Normal, value, {} };
}
// 6.2.3.3 ThrowCompletion ( value ), https://tc39.es/ecma262/#sec-throwcompletion
inline Completion throw_completion(Value value)
{
return { Completion::Type::Throw, value, {} };
}
}
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