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authorGravatar Abseil Team <absl-team@google.com>2019-12-19 12:03:35 -0800
committerGravatar CJ Johnson <johnsoncj@google.com>2019-12-19 15:40:56 -0500
commitad904b6cd3906ddf79878003d92b7bc08d7786ae (patch)
treef30a1740ab8e8b7c3ea37e6d0cb94bfd820b72e7
parent7bd1935dcbaf08701798d17fe408c960adec2da4 (diff)
Export of internal Abseil changes
-- 24162e64040e89f174531fa78fc0ff43c3a67da4 by Abseil Team <absl-team@google.com>: Make ABSL_RETIRED_FLAG behave consistently with ABSL_FLAG. Before the change: ABSL_RETIRED_FLAG does not compile when there are competing ctors in the type, even when ABSL_FLAG does. After the change: ABSL_RETIRED_FLAG compiles when ABSL_FLAG does. PiperOrigin-RevId: 286437395 -- 870d4cb4d114813e9cefe30d26d020b0fdcdc4b4 by Tom Manshreck <shreck@google.com>: Add docs on bind_front PiperOrigin-RevId: 286433540 -- b0c328bd9bb64e0382f942f93b85054229dafeac by Tom Manshreck <shreck@google.com>: Specify the format for LogSeverity flags PiperOrigin-RevId: 286402811 GitOrigin-RevId: 24162e64040e89f174531fa78fc0ff43c3a67da4 Change-Id: I89785145d049fee49c6b9cf3357893ece9a6231c
-rw-r--r--absl/base/log_severity.h52
-rw-r--r--absl/flags/flag.h12
-rw-r--r--absl/flags/flag_test.cc23
-rw-r--r--absl/flags/internal/flag.h14
-rw-r--r--absl/functional/bind_front.h58
5 files changed, 126 insertions, 33 deletions
diff --git a/absl/base/log_severity.h b/absl/base/log_severity.h
index e247c4a9..65a3b166 100644
--- a/absl/base/log_severity.h
+++ b/absl/base/log_severity.h
@@ -24,19 +24,45 @@
namespace absl {
ABSL_NAMESPACE_BEGIN
-// Four severity levels are defined. Logging APIs should terminate the program
+// absl::LogSeverity
+//
+// Four severity levels are defined. Logging APIs should terminate the program
// when a message is logged at severity `kFatal`; the other levels have no
// special semantics.
//
-// Abseil flags may be defined with type `LogSeverity`. Dependency layering
-// constraints require that the `AbslParseFlag` overload be declared and defined
-// in the flags module rather than here. The `AbslUnparseFlag` overload is
-// defined there too for consistency.
+// Values other than the four defined levels (e.g. produced by `static_cast`)
+// are valid, but their semantics when passed to a function, macro, or flag
+// depend on the function, macro, or flag. The usual behavior is to normalize
+// such values to a defined severity level, however in some cases values other
+// than the defined levels are useful for comparison.
+//
+// Exmaple:
+//
+// // Effectively disables all logging:
+// SetMinLogLevel(static_cast<absl::LogSeverity>(100));
+//
+// Abseil flags may be defined with type `LogSeverity`. Dependency layering
+// constraints require that the `AbslParseFlag()` overload be declared and
+// defined in the flags library itself rather than here. The `AbslUnparseFlag()`
+// overload is defined there as well for consistency.
+//
+// absl::LogSeverity Flag String Representation
+//
+// An `absl::LogSeverity` has a string representation used for parsing
+// command-line flags based on the enumerator name (e.g. `kFatal`) or
+// its unprefixed name (without the `k`) in any case-insensitive form. (E.g.
+// "FATAL", "fatal" or "Fatal" are all valid.) Unparsing such flags produces an
+// unprefixed string representation in all caps (e.g. "FATAL") or an integer.
//
-// The parser accepts arbitrary integers (as if the type were `int`). It also
-// accepts each named enumerator, without regard for case, with or without the
-// leading 'k'. For example: "kInfo", "INFO", and "info" all parse to the value
-// `absl::LogSeverity::kInfo`.
+// Additionally, the parser accepts arbitrary integers (as if the type were
+// `int`).
+//
+// Examples:
+//
+// --my_log_level=kInfo
+// --my_log_level=INFO
+// --my_log_level=info
+// --my_log_level=0
//
// Unparsing a flag produces the same result as `absl::LogSeverityName()` for
// the standard levels and a base-ten integer otherwise.
@@ -47,6 +73,8 @@ enum class LogSeverity : int {
kFatal = 3,
};
+// LogSeverities()
+//
// Returns an iterable of all standard `absl::LogSeverity` values, ordered from
// least to most severe.
constexpr std::array<absl::LogSeverity, 4> LogSeverities() {
@@ -54,6 +82,8 @@ constexpr std::array<absl::LogSeverity, 4> LogSeverities() {
absl::LogSeverity::kError, absl::LogSeverity::kFatal}};
}
+// LogSeverityName()
+//
// Returns the all-caps string representation (e.g. "INFO") of the specified
// severity level if it is one of the standard levels and "UNKNOWN" otherwise.
constexpr const char* LogSeverityName(absl::LogSeverity s) {
@@ -66,6 +96,8 @@ constexpr const char* LogSeverityName(absl::LogSeverity s) {
: s == absl::LogSeverity::kFatal ? "FATAL" : "UNKNOWN";
}
+// NormalizeLogSeverity()
+//
// Values less than `kInfo` normalize to `kInfo`; values greater than `kFatal`
// normalize to `kError` (**NOT** `kFatal`).
constexpr absl::LogSeverity NormalizeLogSeverity(absl::LogSeverity s) {
@@ -77,6 +109,8 @@ constexpr absl::LogSeverity NormalizeLogSeverity(int s) {
return absl::NormalizeLogSeverity(static_cast<absl::LogSeverity>(s));
}
+// operator<<
+//
// The exact representation of a streamed `absl::LogSeverity` is deliberately
// unspecified; do not rely on it.
std::ostream& operator<<(std::ostream& os, absl::LogSeverity s);
diff --git a/absl/flags/flag.h b/absl/flags/flag.h
index b6fbd116..f18e9f56 100644
--- a/absl/flags/flag.h
+++ b/absl/flags/flag.h
@@ -384,11 +384,19 @@ ABSL_NAMESPACE_END
//
// `default_value` is only used as a double check on the type. `explanation` is
// unused.
+//
+// ABSL_RETIRED_FLAG support omitting the default value for default
+// constructible value type, so that users can delete the code generatring this
+// value.
+//
// TODO(rogeeff): Return an anonymous struct instead of bool, and place it into
// the unnamed namespace.
#define ABSL_RETIRED_FLAG(type, flagname, default_value, explanation) \
- ABSL_ATTRIBUTE_UNUSED static const bool ignored_##flagname = \
- ([] { return type(default_value); }, \
+ ABSL_ATTRIBUTE_UNUSED static const bool ignored_##flagname = \
+ ([] { \
+ return absl::flags_internal::MakeFromDefaultValueOrEmpty<type>( \
+ default_value); \
+ }, \
absl::flags_internal::RetiredFlag<type>(#flagname))
#endif // ABSL_FLAGS_FLAG_H_
diff --git a/absl/flags/flag_test.cc b/absl/flags/flag_test.cc
index 4e08da85..465f018c 100644
--- a/absl/flags/flag_test.cc
+++ b/absl/flags/flag_test.cc
@@ -486,11 +486,30 @@ TEST_F(FlagTest, TestNonDefaultConstructibleType) {
// --------------------------------------------------------------------
+struct Wrapper {
+ Wrapper() {}
+
+ // NOLINTNEXTLINE(runtime/explicit)
+ Wrapper(const std::string& val) : val(val) {}
+
+ // NOLINTNEXTLINE(runtime/explicit)
+ template <typename T>
+ Wrapper(T&& t) : val(std::forward<T>(t)) {}
+
+ // NOLINTNEXTLINE(runtime/explicit)
+ operator std::string() const& { return val; }
+
+ std::string val;
+};
+
} // namespace
ABSL_RETIRED_FLAG(bool, old_bool_flag, true, "old descr");
ABSL_RETIRED_FLAG(int, old_int_flag, (int)std::sqrt(10), "old descr");
ABSL_RETIRED_FLAG(std::string, old_str_flag, "", absl::StrCat("old ", "descr"));
+ABSL_RETIRED_FLAG(Wrapper, old_wrapper_flag, {}, "old wrapper");
+ABSL_RETIRED_FLAG(Wrapper, old_wrapper_no_default_flag, ,
+ "old wrapper no default");
namespace {
@@ -502,6 +521,10 @@ TEST_F(FlagTest, TestRetiredFlagRegistration) {
EXPECT_FALSE(is_bool);
EXPECT_TRUE(flags::IsRetiredFlag("old_str_flag", &is_bool));
EXPECT_FALSE(is_bool);
+ EXPECT_TRUE(flags::IsRetiredFlag("old_wrapper_flag", &is_bool));
+ EXPECT_FALSE(is_bool);
+ EXPECT_TRUE(flags::IsRetiredFlag("old_wrapper_no_default_flag", &is_bool));
+ EXPECT_FALSE(is_bool);
EXPECT_FALSE(flags::IsRetiredFlag("some_other_flag", &is_bool));
}
diff --git a/absl/flags/internal/flag.h b/absl/flags/internal/flag.h
index 20de406f..21a10c7f 100644
--- a/absl/flags/internal/flag.h
+++ b/absl/flags/internal/flag.h
@@ -416,6 +416,20 @@ T* MakeFromDefaultValue(EmptyBraces) {
return new T;
}
+// MakeFromDefaultValueOrEmpty is basically the same as MakeFromDefaultValue. It
+// also allows for empty macro parameter (hence no argument), which was somehow
+// widely used for ABSL_RETIRED_FLAG().
+
+template <typename T>
+T* MakeFromDefaultValueOrEmpty(T t) {
+ return MakeFromDefaultValue(std::move(t));
+}
+
+template <typename T>
+T* MakeFromDefaultValueOrEmpty() {
+ return MakeFromDefaultValue<T>(EmptyBraces());
+}
+
} // namespace flags_internal
ABSL_NAMESPACE_END
} // namespace absl
diff --git a/absl/functional/bind_front.h b/absl/functional/bind_front.h
index 4c61d0ec..8448d7b3 100644
--- a/absl/functional/bind_front.h
+++ b/absl/functional/bind_front.h
@@ -11,17 +11,44 @@
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
-
+//
+// -----------------------------------------------------------------------------
+// File: bind_front.h
+// -----------------------------------------------------------------------------
+//
// `absl::bind_front()` returns a functor by binding a number of arguments to
-// the front of a provided functor, allowing you to avoid known problems with
-// `std::bind()`. It is a form of partial function application
-// https://en.wikipedia.org/wiki/Partial_application.
+// the front of a provided (usually more generic) functor. Unlike `std::bind`,
+// it does not require the use of argument placeholders. The simpler syntax of
+// `absl::bind_front()` allows you to avoid known misuses with `std::bind()`.
+//
+// `absl::bind_front()` is meant as a drop-in replacement for C++20's upcoming
+// `std::bind_front()`, which similarly resolves these issues with
+// `std::bind()`. Both `bind_front()` alternatives, unlike `std::bind()`, allow
+// partial function application. (See
+// https://en.wikipedia.org/wiki/Partial_application).
+
+#ifndef ABSL_FUNCTIONAL_BIND_FRONT_H_
+#define ABSL_FUNCTIONAL_BIND_FRONT_H_
+
+#include "absl/functional/internal/front_binder.h"
+#include "absl/utility/utility.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+
+// bind_front()
+//
+// Binds the first N arguments of an invocable object and stores them by value,
+// except types of `std::reference_wrapper` which are 'unwound' and stored by
+// reference.
//
-// Like `std::bind()` it is implicitly convertible to `std::function`. In
-// particular, it may be used as a simpler replacement for `std::bind()` in most
-// cases, as it does not require placeholders to be specified. More
-// importantly, it provides more reliable correctness guarantees than
-// `std::bind()`.
+// Like `std::bind()`, `absl::bind_front()` is implicitly convertible to
+// `std::function`. In particular, it may be used as a simpler replacement for
+// `std::bind()` in most cases, as it does not require placeholders to be
+// specified. More importantly, it provides more reliable correctness guarantees
+// than `std::bind()`; while `std::bind()` will silently ignore passing more
+// parameters than expected, for example, `absl::bind_front()` will report such
+// mis-uses as errors.
//
// absl::bind_front(a...) can be seen as storing the results of
// std::make_tuple(a...).
@@ -125,19 +152,6 @@
// // dangling references.
// foo->DoInFuture(absl::bind_front(Print, std::ref(hi), "Guest")); // BAD!
// auto f = absl::bind_front(Print, std::ref(hi), "Guest"); // BAD!
-
-#ifndef ABSL_FUNCTIONAL_BIND_FRONT_H_
-#define ABSL_FUNCTIONAL_BIND_FRONT_H_
-
-#include "absl/functional/internal/front_binder.h"
-#include "absl/utility/utility.h"
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-
-// Binds the first N arguments of an invocable object and stores them by value,
-// except types of std::reference_wrapper which are 'unwound' and stored by
-// reference.
template <class F, class... BoundArgs>
constexpr functional_internal::bind_front_t<F, BoundArgs...> bind_front(
F&& func, BoundArgs&&... args) {