THUAI6/CAPI/cpp/grpc/include/absl/base/log_severity.h

// 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 ABSL_BASE_LOG_SEVERITY_H_
#define ABSL_BASE_LOG_SEVERITY_H_

#include <array>
#include <ostream>

#include "absl/base/attributes.h"
#include "absl/base/config.h"

namespace absl
{
    ABSL_NAMESPACE_BEGIN

    // 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<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.
    //
    // 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.
    enum class LogSeverity : int
    {
        kInfo = 0,
        kWarning = 1,
        kError = 2,
        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()
    {
        return {{absl::LogSeverity::kInfo, absl::LogSeverity::kWarning, 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)
    {
        return s == absl::LogSeverity::kInfo ? "INFO" : s == absl::LogSeverity::kWarning ? "WARNING" :
                                                    s == absl::LogSeverity::kError       ? "ERROR" :
                                                    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)
    {
        return s < absl::LogSeverity::kInfo ? absl::LogSeverity::kInfo : s > absl::LogSeverity::kFatal ? absl::LogSeverity::kError :
                                                                                                         s;
    }
    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);

    // 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. 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>(absl::LogSeverity::kInfo),
        kWarning = static_cast<int>(absl::LogSeverity::kWarning),
        kError = static_cast<int>(absl::LogSeverity::kError),
        kFatal = static_cast<int>(absl::LogSeverity::kFatal),
        kInfinity = 1000,
    };

    std::ostream& operator<<(std::ostream& os, 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.
    // 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>(absl::LogSeverity::kInfo),
        kWarning = static_cast<int>(absl::LogSeverity::kWarning),
        kError = static_cast<int>(absl::LogSeverity::kError),
        kFatal = static_cast<int>(absl::LogSeverity::kFatal),
    };

    std::ostream& operator<<(std::ostream& os, absl::LogSeverityAtMost s);

#define COMPOP(op1, op2, T)                                         \
    constexpr bool operator op1(absl::T lhs, absl::LogSeverity rhs) \
    {                                                               \
        return static_cast<absl::LogSeverity>(lhs) op1 rhs;         \
    }                                                               \
    constexpr bool operator op2(absl::LogSeverity lhs, absl::T rhs) \
    {                                                               \
        return lhs op2 static_cast<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

    ABSL_NAMESPACE_END
}  // namespace absl

#endif  // ABSL_BASE_LOG_SEVERITY_H_