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-rw-r--r--abseil-cpp/absl/flags/flag.h122
1 files changed, 18 insertions, 104 deletions
diff --git a/abseil-cpp/absl/flags/flag.h b/abseil-cpp/absl/flags/flag.h
index a9cb2b7..b7f94be 100644
--- a/abseil-cpp/absl/flags/flag.h
+++ b/abseil-cpp/absl/flags/flag.h
@@ -67,105 +67,15 @@ ABSL_NAMESPACE_BEGIN
// ABSL_FLAG(int, count, 0, "Count of items to process");
//
// No public methods of `absl::Flag<T>` are part of the Abseil Flags API.
+//
+// For type support of Abseil Flags, see the marshalling.h header file, which
+// discusses supported standard types, optional flags, and additional Abseil
+// type support.
#if !defined(_MSC_VER) || defined(__clang__)
template <typename T>
using Flag = flags_internal::Flag<T>;
#else
-// MSVC debug builds do not implement initialization with constexpr constructors
-// correctly. To work around this we add a level of indirection, so that the
-// class `absl::Flag` contains an `internal::Flag*` (instead of being an alias
-// to that class) and dynamically allocates an instance when necessary. We also
-// forward all calls to internal::Flag methods via trampoline methods. In this
-// setup the `absl::Flag` class does not have constructor and virtual methods,
-// all the data members are public and thus MSVC is able to initialize it at
-// link time. To deal with multiple threads accessing the flag for the first
-// time concurrently we use an atomic boolean indicating if flag object is
-// initialized. We also employ the double-checked locking pattern where the
-// second level of protection is a global Mutex, so if two threads attempt to
-// construct the flag concurrently only one wins.
-// This solution is based on a recomendation here:
-// https://developercommunity.visualstudio.com/content/problem/336946/class-with-constexpr-constructor-not-using-static.html?childToView=648454#comment-648454
-
-namespace flags_internal {
-absl::Mutex* GetGlobalConstructionGuard();
-} // namespace flags_internal
-
-template <typename T>
-class Flag {
- public:
- // No constructor and destructor to ensure this is an aggregate type.
- // Visual Studio 2015 still requires the constructor for class to be
- // constexpr initializable.
-#if _MSC_VER <= 1900
- constexpr Flag(const char* name, const char* filename,
- const flags_internal::HelpGenFunc help_gen,
- const flags_internal::FlagDfltGenFunc default_value_gen)
- : name_(name),
- filename_(filename),
- help_gen_(help_gen),
- default_value_gen_(default_value_gen),
- inited_(false),
- impl_(nullptr) {}
-#endif
-
- flags_internal::Flag<T>& GetImpl() const {
- if (!inited_.load(std::memory_order_acquire)) {
- absl::MutexLock l(flags_internal::GetGlobalConstructionGuard());
-
- if (inited_.load(std::memory_order_acquire)) {
- return *impl_;
- }
-
- impl_ = new flags_internal::Flag<T>(
- name_, filename_,
- {flags_internal::FlagHelpMsg(help_gen_),
- flags_internal::FlagHelpKind::kGenFunc},
- {flags_internal::FlagDefaultSrc(default_value_gen_),
- flags_internal::FlagDefaultKind::kGenFunc});
- inited_.store(true, std::memory_order_release);
- }
-
- return *impl_;
- }
-
- // Public methods of `absl::Flag<T>` are NOT part of the Abseil Flags API.
- // See https://abseil.io/docs/cpp/guides/flags
- bool IsRetired() const { return GetImpl().IsRetired(); }
- absl::string_view Name() const { return GetImpl().Name(); }
- std::string Help() const { return GetImpl().Help(); }
- bool IsModified() const { return GetImpl().IsModified(); }
- bool IsSpecifiedOnCommandLine() const {
- return GetImpl().IsSpecifiedOnCommandLine();
- }
- std::string Filename() const { return GetImpl().Filename(); }
- std::string DefaultValue() const { return GetImpl().DefaultValue(); }
- std::string CurrentValue() const { return GetImpl().CurrentValue(); }
- template <typename U>
- inline bool IsOfType() const {
- return GetImpl().template IsOfType<U>();
- }
- T Get() const {
- return flags_internal::FlagImplPeer::InvokeGet<T>(GetImpl());
- }
- void Set(const T& v) {
- flags_internal::FlagImplPeer::InvokeSet(GetImpl(), v);
- }
- void InvokeCallback() { GetImpl().InvokeCallback(); }
-
- const CommandLineFlag& Reflect() const {
- return flags_internal::FlagImplPeer::InvokeReflect(GetImpl());
- }
-
- // The data members are logically private, but they need to be public for
- // this to be an aggregate type.
- const char* name_;
- const char* filename_;
- const flags_internal::HelpGenFunc help_gen_;
- const flags_internal::FlagDfltGenFunc default_value_gen_;
-
- mutable std::atomic<bool> inited_;
- mutable flags_internal::Flag<T>* impl_;
-};
+#include "absl/flags/internal/flag_msvc.inc"
#endif
// GetFlag()
@@ -265,6 +175,8 @@ ABSL_NAMESPACE_END
//
// ABSL_FLAG(T, name, default_value, help).OnUpdate(callback);
//
+// `callback` should be convertible to `void (*)()`.
+//
// After any setting of the flag value, the callback will be called at least
// once. A rapid sequence of changes may be merged together into the same
// callback. No concurrent calls to the callback will be made for the same
@@ -279,7 +191,6 @@ ABSL_NAMESPACE_END
// Note: ABSL_FLAG.OnUpdate() does not have a public definition. Hence, this
// comment serves as its API documentation.
-
// -----------------------------------------------------------------------------
// Implementation details below this section
// -----------------------------------------------------------------------------
@@ -301,13 +212,15 @@ ABSL_NAMESPACE_END
#if ABSL_FLAGS_STRIP_NAMES
#define ABSL_FLAG_IMPL_FLAGNAME(txt) ""
#define ABSL_FLAG_IMPL_FILENAME() ""
-#define ABSL_FLAG_IMPL_REGISTRAR(T, flag) \
- absl::flags_internal::FlagRegistrar<T, false>(ABSL_FLAG_IMPL_FLAG_PTR(flag))
+#define ABSL_FLAG_IMPL_REGISTRAR(T, flag) \
+ absl::flags_internal::FlagRegistrar<T, false>(ABSL_FLAG_IMPL_FLAG_PTR(flag), \
+ nullptr)
#else
#define ABSL_FLAG_IMPL_FLAGNAME(txt) txt
#define ABSL_FLAG_IMPL_FILENAME() __FILE__
-#define ABSL_FLAG_IMPL_REGISTRAR(T, flag) \
- absl::flags_internal::FlagRegistrar<T, true>(ABSL_FLAG_IMPL_FLAG_PTR(flag))
+#define ABSL_FLAG_IMPL_REGISTRAR(T, flag) \
+ absl::flags_internal::FlagRegistrar<T, true>(ABSL_FLAG_IMPL_FLAG_PTR(flag), \
+ __FILE__)
#endif
// ABSL_FLAG_IMPL macro definition conditional on ABSL_FLAGS_STRIP_HELP
@@ -332,8 +245,8 @@ ABSL_NAMESPACE_END
/* default value argument. That keeps temporaries alive */ \
/* long enough for NonConst to work correctly. */ \
static constexpr absl::string_view Value( \
- absl::string_view v = ABSL_FLAG_IMPL_FLAGHELP(txt)) { \
- return v; \
+ absl::string_view absl_flag_help = ABSL_FLAG_IMPL_FLAGHELP(txt)) { \
+ return absl_flag_help; \
} \
static std::string NonConst() { return std::string(Value()); } \
}; \
@@ -345,8 +258,8 @@ ABSL_NAMESPACE_END
#define ABSL_FLAG_IMPL_DECLARE_DEF_VAL_WRAPPER(name, Type, default_value) \
struct AbslFlagDefaultGenFor##name { \
Type value = absl::flags_internal::InitDefaultValue<Type>(default_value); \
- static void Gen(void* p) { \
- new (p) Type(AbslFlagDefaultGenFor##name{}.value); \
+ static void Gen(void* absl_flag_default_loc) { \
+ new (absl_flag_default_loc) Type(AbslFlagDefaultGenFor##name{}.value); \
} \
};
@@ -356,6 +269,7 @@ ABSL_NAMESPACE_END
// 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) \
+ extern ::absl::Flag<Type> FLAGS_##name; \
namespace absl /* block flags in namespaces */ {} \
ABSL_FLAG_IMPL_DECLARE_DEF_VAL_WRAPPER(name, Type, default_value) \
ABSL_FLAG_IMPL_DECLARE_HELP_WRAPPER(name, help) \
generated by cgit v1.2.3 (git 2.25.1) at 2024-05-29 18:54:44 +0000