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// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// 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.
#ifndef Y_ABSL_BASE_LOG_SEVERITY_H_
#define Y_ABSL_BASE_LOG_SEVERITY_H_
#include <array>
#include <ostream>
#include "y_absl/base/attributes.h"
#include "y_absl/base/config.h"
namespace y_absl {
Y_ABSL_NAMESPACE_BEGIN
// y_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.
//
// 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.
//
// Example:
//
// // Effectively disables all logging:
// SetMinLogLevel(static_cast<y_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.
//
// y_absl::LogSeverity Flag String Representation
//
// An `y_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.
//
// 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
//
// `DFATAL` and `kLogDebugFatal` are similarly accepted.
//
// Unparsing a flag produces the same result as `y_absl::LogSeverityName()` for
// the standard levels and a base-ten integer otherwise.
enum class LogSeverity : int {
kInfo = 0,
kWarning = 1,
kError = 2,
kFatal = 3,
};
// LogSeverities()
//
// Returns an iterable of all standard `y_absl::LogSeverity` values, ordered from
// least to most severe.
constexpr std::array<y_absl::LogSeverity, 4> LogSeverities() {
return {{y_absl::LogSeverity::kInfo, y_absl::LogSeverity::kWarning,
y_absl::LogSeverity::kError, y_absl::LogSeverity::kFatal}};
}
// `y_absl::kLogDebugFatal` equals `y_absl::LogSeverity::kFatal` in debug builds
// (i.e. when `NDEBUG` is not defined) and `y_absl::LogSeverity::kError`
// otherwise. Avoid ODR-using this variable as it has internal linkage and thus
// distinct storage in different TUs.
#ifdef NDEBUG
static constexpr y_absl::LogSeverity kLogDebugFatal = y_absl::LogSeverity::kError;
#else
static constexpr y_absl::LogSeverity kLogDebugFatal = y_absl::LogSeverity::kFatal;
#endif
// 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(y_absl::LogSeverity s) {
switch (s) {
case y_absl::LogSeverity::kInfo: return "INFO";
case y_absl::LogSeverity::kWarning: return "WARNING";
case y_absl::LogSeverity::kError: return "ERROR";
case y_absl::LogSeverity::kFatal: return "FATAL";
}
return "UNKNOWN";
}
// NormalizeLogSeverity()
//
// Values less than `kInfo` normalize to `kInfo`; values greater than `kFatal`
// normalize to `kError` (**NOT** `kFatal`).
constexpr y_absl::LogSeverity NormalizeLogSeverity(y_absl::LogSeverity s) {
y_absl::LogSeverity n = s;
if (n < y_absl::LogSeverity::kInfo) n = y_absl::LogSeverity::kInfo;
if (n > y_absl::LogSeverity::kFatal) n = y_absl::LogSeverity::kError;
return n;
}
constexpr y_absl::LogSeverity NormalizeLogSeverity(int s) {
return y_absl::NormalizeLogSeverity(static_cast<y_absl::LogSeverity>(s));
}
// operator<<
//
// The exact representation of a streamed `y_absl::LogSeverity` is deliberately
// unspecified; do not rely on it.
std::ostream& operator<<(std::ostream& os, y_absl::LogSeverity s);
// Enums representing a lower bound for LogSeverity. APIs that only operate on
// messages of at least a certain level (for example, `SetMinLogLevel()`) use
// this type to specify that level. y_absl::LogSeverityAtLeast::kInfinity is
// a level above all threshold levels and therefore no log message will
// ever meet this threshold.
enum class LogSeverityAtLeast : int {
kInfo = static_cast<int>(y_absl::LogSeverity::kInfo),
kWarning = static_cast<int>(y_absl::LogSeverity::kWarning),
kError = static_cast<int>(y_absl::LogSeverity::kError),
kFatal = static_cast<int>(y_absl::LogSeverity::kFatal),
kInfinity = 1000,
};
std::ostream& operator<<(std::ostream& os, y_absl::LogSeverityAtLeast s);
// Enums representing an upper bound for LogSeverity. APIs that only operate on
// messages of at most a certain level (for example, buffer all messages at or
// below a certain level) use this type to specify that level.
// y_absl::LogSeverityAtMost::kNegativeInfinity is a level below all threshold
// levels and therefore will exclude all log messages.
enum class LogSeverityAtMost : int {
kNegativeInfinity = -1000,
kInfo = static_cast<int>(y_absl::LogSeverity::kInfo),
kWarning = static_cast<int>(y_absl::LogSeverity::kWarning),
kError = static_cast<int>(y_absl::LogSeverity::kError),
kFatal = static_cast<int>(y_absl::LogSeverity::kFatal),
};
std::ostream& operator<<(std::ostream& os, y_absl::LogSeverityAtMost s);
#define COMPOP(op1, op2, T) \
constexpr bool operator op1(y_absl::T lhs, y_absl::LogSeverity rhs) { \
return static_cast<y_absl::LogSeverity>(lhs) op1 rhs; \
} \
constexpr bool operator op2(y_absl::LogSeverity lhs, y_absl::T rhs) { \
return lhs op2 static_cast<y_absl::LogSeverity>(rhs); \
}
// Comparisons between `LogSeverity` and `LogSeverityAtLeast`/
// `LogSeverityAtMost` are only supported in one direction.
// Valid checks are:
// LogSeverity >= LogSeverityAtLeast
// LogSeverity < LogSeverityAtLeast
// LogSeverity <= LogSeverityAtMost
// LogSeverity > LogSeverityAtMost
COMPOP(>, <, LogSeverityAtLeast)
COMPOP(<=, >=, LogSeverityAtLeast)
COMPOP(<, >, LogSeverityAtMost)
COMPOP(>=, <=, LogSeverityAtMost)
#undef COMPOP
Y_ABSL_NAMESPACE_END
} // namespace y_absl
#endif // Y_ABSL_BASE_LOG_SEVERITY_H_
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