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// Copyright 2021 Google LLC
//
// 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.
// A basic logging system built with command-line utilities in mind.
#ifndef GSRSUP_LOG_H_
#define GSRSUP_LOG_H_
#include <limits>
#include <ostream>
#include <string>
#include <absl/strings/str_cat.h>
#include <absl/strings/string_view.h>
#include <stdlib.h>
namespace gsrsup {
// A logger object backed by a std::ostream (or by nothing, if the ostream is
// null).
//
// This class inherits the thread-safety properties of its underlying ostream.
class Log final {
public:
enum Level : int {
kDebug = 0,
kInfo = 1,
kWarning = 2,
kError = 3,
kNeverPrint = std::numeric_limits<int>::max(),
};
explicit Log(absl::string_view program, Level minimum_level,
std::ostream* out)
: prefix_(program), minimum_level_(minimum_level), out_(out) {}
explicit Log(absl::string_view program, Level minimum_level,
std::ostream& out)
: Log(program, minimum_level, &out) {}
explicit Log(absl::string_view program, std::ostream* out)
: Log(program, kInfo, out) {}
explicit Log(absl::string_view program, std::ostream& out)
: Log(program, &out) {}
Log(const Log&) = default;
Log& operator=(const Log&) = default;
template <typename... Args>
void Message(Level, Args...);
template <typename... Args>
void Debug(Args... args) {
Message(kDebug, args...);
}
template <typename... Args>
void Info(Args... args) {
Message(kInfo, args...);
}
template <typename... Args>
void Warning(Args... args) {
Message(kWarning, args...);
}
template <typename... Args>
void Error(Args... args) {
Message(kError, args...);
}
private:
std::string prefix_;
Level minimum_level_;
std::ostream* out_;
};
template <typename... Args>
void Log::Message(Level level, Args... args) {
if (level < minimum_level_ || out_ == nullptr) {
return;
}
absl::string_view level_str;
switch (level) {
case kDebug:
level_str = "debug: ";
break;
case kWarning:
level_str = "warning: ";
break;
case kError:
level_str = "error: ";
break;
default:
break;
}
std::string message = absl::StrCat(prefix_, ": ", level_str, args..., "\n");
out_->write(message.data(), message.size());
}
// If condition is false, logs an internal error and exits the program.
void Check(Log& log, bool condition, const char* condition_str,
const char* file, int line);
} // namespace gsrsup
// A convenience macro to invoke the Check function.
#define CHECK(log, condition) \
::gsrsup::Check((log), (condition), #condition, __FILE__, __LINE__)
#endif // GSRSUP_LOG_H_
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