diff options
Diffstat (limited to 'absl/flags/flag.h')
| -rw-r--r-- | absl/flags/flag.h | 51 |
1 files changed, 14 insertions, 37 deletions
diff --git a/absl/flags/flag.h b/absl/flags/flag.h index 193755e5..c70023ab 100644 --- a/absl/flags/flag.h +++ b/absl/flags/flag.h @@ -91,30 +91,7 @@ T GetFlag(const absl::Flag<T>& flag) { ABSL_FLAGS_INTERNAL_FOR_EACH_LOCK_FREE(ABSL_FLAGS_INTERNAL_LOCK_FREE_VALIDATE) #undef ABSL_FLAGS_INTERNAL_LOCK_FREE_VALIDATE - // Implementation notes: - // - // We are wrapping a union around the value of `T` to serve three purposes: - // - // 1. `U.value` has correct size and alignment for a value of type `T` - // 2. The `U.value` constructor is not invoked since U's constructor does not - // do it explicitly. - // 3. The `U.value` destructor is invoked since U's destructor does it - // explicitly. This makes `U` a kind of RAII wrapper around non default - // constructible value of T, which is destructed when we leave the scope. - // We do need to destroy U.value, which is constructed by - // CommandLineFlag::Read even though we left it in a moved-from state - // after std::move. - // - // All of this serves to avoid requiring `T` being default constructible. - union U { - T value; - U() {} - ~U() { value.~T(); } - }; - U u; - - flag.internal.Read(&u.value, &flags_internal::FlagOps<T>); - return std::move(u.value); + return flag.Get(); } // Overload for `GetFlag()` for types that support lock-free reads. @@ -132,7 +109,7 @@ ABSL_FLAGS_INTERNAL_FOR_EACH_LOCK_FREE(ABSL_FLAGS_INTERNAL_LOCK_FREE_EXPORT) // but especially within performance-critical code. template <typename T> void SetFlag(absl::Flag<T>* flag, const T& v) { - flag->internal.Write(&v, &flags_internal::FlagOps<T>); + flag->Set(v); } // Overload of `SetFlag()` to allow callers to pass in a value that is @@ -141,7 +118,7 @@ void SetFlag(absl::Flag<T>* flag, const T& v) { template <typename T, typename V> void SetFlag(absl::Flag<T>* flag, const V& v) { T value(v); - SetFlag<T>(flag, value); + flag->Set(value); } } // namespace absl @@ -239,17 +216,17 @@ void SetFlag(absl::Flag<T>* flag, const V& v) { // Note: Name of registrar object is not arbitrary. It is used to "grab" // global name for FLAGS_no<flag_name> symbol, thus preventing the possibility // of defining two flags with names foo and nofoo. -#define ABSL_FLAG_IMPL(Type, name, default_value, help) \ - namespace absl {} \ - ABSL_FLAG_IMPL_DECLARE_DEF_VAL_WRAPPER(name, Type, default_value) \ - ABSL_FLAG_IMPL_DECLARE_HELP_WRAPPER(name, help) \ - absl::Flag<Type> FLAGS_##name( \ - ABSL_FLAG_IMPL_FLAGNAME(#name), \ - &AbslFlagsWrapHelp##name, \ - ABSL_FLAG_IMPL_FILENAME(), \ - &absl::flags_internal::FlagMarshallingOps<Type>, \ - &AbslFlagsInitFlag##name); \ - extern bool FLAGS_no##name; \ +#define ABSL_FLAG_IMPL(Type, name, default_value, help) \ + namespace absl {} \ + ABSL_FLAG_IMPL_DECLARE_DEF_VAL_WRAPPER(name, Type, default_value) \ + ABSL_FLAG_IMPL_DECLARE_HELP_WRAPPER(name, help) \ + absl::Flag<Type> FLAGS_##name( \ + ABSL_FLAG_IMPL_FLAGNAME(#name), \ + &AbslFlagsWrapHelp##name, \ + ABSL_FLAG_IMPL_FILENAME(), \ + &absl::flags_internal::FlagMarshallingOps<Type>, \ + &AbslFlagsInitFlag##name); \ + extern bool FLAGS_no##name; \ bool FLAGS_no##name = ABSL_FLAG_IMPL_REGISTRAR(Type, FLAGS_##name) // ABSL_RETIRED_FLAG |