ladybird/AK/Try.h
Jonne Ransijn d5fbf7323a AK+LibJS: Allow {TRY,MUST}{,_OR_THROW_OOM} on list-initializers
List initializers may contain commas without surrounding parenthesis,
causing them to be passed as multiple macro arguments.
2024-12-04 16:45:58 +00:00

48 lines
2.9 KiB
C

/*
* Copyright (c) 2021, Andreas Kling <andreas@ladybird.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Diagnostics.h>
#include <AK/StdLibExtras.h>
// This macro is redefined in `AK/Format.h` to give a nicer error message.
#define AK_HANDLE_UNEXPECTED_ERROR(result) VERIFY(!result.is_error());
// NOTE: This macro works with any result type that has the expected APIs.
// It's designed with AK::Result and AK::Error in mind.
//
// It depends on a non-standard C++ extension, specifically
// on statement expressions [1]. This is known to be implemented
// by at least clang and gcc.
// [1] https://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html
//
// If the static_assert below is triggered, it means you tried to return a reference
// from a fallible expression. This will not do what you want; the statement expression
// will create a copy regardless, so it is explicitly disallowed.
#define TRY(...) \
({ \
/* Ignore -Wshadow to allow nesting the macro. */ \
AK_IGNORE_DIAGNOSTIC("-Wshadow", \
auto&& _temporary_result = (__VA_ARGS__)); \
static_assert(!::AK::Detail::IsLvalueReference<decltype(_temporary_result.release_value())>, \
"Do not return a reference from a fallible expression"); \
if (_temporary_result.is_error()) [[unlikely]] \
return _temporary_result.release_error(); \
_temporary_result.release_value(); \
})
#define MUST(...) \
({ \
/* Ignore -Wshadow to allow nesting the macro. */ \
AK_IGNORE_DIAGNOSTIC("-Wshadow", \
auto&& _temporary_result = (__VA_ARGS__)); \
static_assert(!::AK::Detail::IsLvalueReference<decltype(_temporary_result.release_value())>, \
"Do not return a reference from a fallible expression"); \
AK_HANDLE_UNEXPECTED_ERROR(_temporary_result) \
_temporary_result.release_value(); \
})