chromium/third_party/abseil-cpp/absl/log/internal/log_message.h

// Copyright 2022 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.
//
// -----------------------------------------------------------------------------
// File: log/internal/log_message.h
// -----------------------------------------------------------------------------
//
// This file declares `class absl::log_internal::LogMessage`. This class more or
// less represents a particular log message. LOG/CHECK macros create a
// temporary instance of `LogMessage` and then stream values to it.  At the end
// of the LOG/CHECK statement, LogMessage instance goes out of scope and
// `~LogMessage` directs the message to the registered log sinks.
// Heap-allocation of `LogMessage` is unsupported.  Construction outside of a
// `LOG` macro is unsupported.

#ifndef ABSL_LOG_INTERNAL_LOG_MESSAGE_H_
#define ABSL_LOG_INTERNAL_LOG_MESSAGE_H_

#include <ios>
#include <memory>
#include <ostream>
#include <streambuf>
#include <string>

#include "absl/base/attributes.h"
#include "absl/base/config.h"
#include "absl/base/internal/errno_saver.h"
#include "absl/base/log_severity.h"
#include "absl/log/internal/nullguard.h"
#include "absl/log/log_entry.h"
#include "absl/log/log_sink.h"
#include "absl/strings/has_absl_stringify.h"
#include "absl/strings/string_view.h"
#include "absl/time/time.h"

namespace absl {
ABSL_NAMESPACE_BEGIN
namespace log_internal {
constexpr int kLogMessageBufferSize = …;

class LogMessage { … };

// Helper class so that `AbslStringify()` can modify the LogMessage.
class StringifySink final { … };

// Note: the following is declared `ABSL_ATTRIBUTE_NOINLINE`
template <typename T,
          typename std::enable_if<absl::HasAbslStringify<T>::value, int>::type>
LogMessage& LogMessage::operator<<(const T& v) { … }

// Note: the following is declared `ABSL_ATTRIBUTE_NOINLINE`
template <typename T,
          typename std::enable_if<!absl::HasAbslStringify<T>::value, int>::type>
LogMessage& LogMessage::operator<<(const T& v) { … }

template <int SIZE>
LogMessage& LogMessage::operator<<(const char (&buf)[SIZE]) { … }

// Note: the following is declared `ABSL_ATTRIBUTE_NOINLINE`
template <int SIZE>
LogMessage& LogMessage::operator<<(char (&buf)[SIZE]) { … }
// We instantiate these specializations in the library's TU to save space in
// other TUs.  Since the template is marked `ABSL_ATTRIBUTE_NOINLINE` we will be
// emitting a function call either way.
extern template LogMessage& LogMessage::operator<<(const char& v);
extern template LogMessage& LogMessage::operator<<(const signed char& v);
extern template LogMessage& LogMessage::operator<<(const unsigned char& v);
extern template LogMessage& LogMessage::operator<<(const short& v);  // NOLINT
extern template LogMessage& LogMessage::operator<<(
    const unsigned short& v);  // NOLINT
extern template LogMessage& LogMessage::operator<<(const int& v);
extern template LogMessage& LogMessage::operator<<(
    const unsigned int& v);                                         // NOLINT
extern template LogMessage& LogMessage::operator<<(const long& v);  // NOLINT
extern template LogMessage& LogMessage::operator<<(
    const unsigned long& v);  // NOLINT
extern template LogMessage& LogMessage::operator<<(
    const long long& v);  // NOLINT
extern template LogMessage& LogMessage::operator<<(
    const unsigned long long& v);  // NOLINT
extern template LogMessage& LogMessage::operator<<(void* const& v);
extern template LogMessage& LogMessage::operator<<(const void* const& v);
extern template LogMessage& LogMessage::operator<<(const float& v);
extern template LogMessage& LogMessage::operator<<(const double& v);
extern template LogMessage& LogMessage::operator<<(const bool& v);

extern template void LogMessage::CopyToEncodedBuffer<
    LogMessage::StringType::kLiteral>(absl::string_view str);
extern template void LogMessage::CopyToEncodedBuffer<
    LogMessage::StringType::kNotLiteral>(absl::string_view str);
extern template void
LogMessage::CopyToEncodedBuffer<LogMessage::StringType::kLiteral>(char ch,
                                                                  size_t num);
extern template void LogMessage::CopyToEncodedBuffer<
    LogMessage::StringType::kNotLiteral>(char ch, size_t num);

// `LogMessageFatal` ensures the process will exit in failure after logging this
// message.
class LogMessageFatal final : public LogMessage { … };

// `LogMessageDebugFatal` ensures the process will exit in failure after logging
// this message. It matches LogMessageFatal but is not [[noreturn]] as it's used
// for DLOG(FATAL) variants.
class LogMessageDebugFatal final : public LogMessage { … };

class LogMessageQuietlyDebugFatal final : public LogMessage { … };

// Used for LOG(QFATAL) to make sure it's properly understood as [[noreturn]].
class LogMessageQuietlyFatal final : public LogMessage { … };

}  // namespace log_internal
ABSL_NAMESPACE_END
}  // namespace absl

extern "C" ABSL_ATTRIBUTE_WEAK void ABSL_INTERNAL_C_SYMBOL(
    AbslInternalOnFatalLogMessage)(const absl::LogEntry&);

#endif  // ABSL_LOG_INTERNAL_LOG_MESSAGE_H_