libcruft-util/log.hpp

/*
 * 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
 *
 *     http://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.
 *
 * Copyright 2012 Danny Robson <danny@nerdcruft.net>
 */

#ifndef __UTIL_LOG_HPP
#define __UTIL_LOG_HPP

#include "nocopy.hpp"

#include <iostream>
#include <string>

// Windows.h or one of its friends defines a macro 'ERROR'. Screw Microsoft.
#ifdef ERROR
#undef ERROR
#endif

namespace util {
    // rfc5424 log levels. It is assumed they are contiguous to simplify array
    // indexing in logging code.
    //
    enum level_t {
        EMERGENCY,              /** system is unusable */
        ALERT,                  /** action must be taken immediately */
        CRITICAL,               /** critical conditions */
        ERROR,                  /** error conditions */
        WARNING,
        WARN = WARNING,         /** warning conditions */
        NOTICE,                 /** normal but significant condition */
        INFORMATIONAL,
        INFO = INFORMATIONAL,   /** informational messages */
        DEBUG,                  /** debug-level messages */

        NUM_LEVELS,
        DEFAULT = INFO
    };

    std::ostream&
    operator<< (std::ostream&, level_t);

    void log (level_t, const std::string &format);

    template <typename ...tail>
    void log (level_t, const std::string &format, tail ..._tail);

    #define LOG_EMERGENCY(...)  do { util::log(util::EMERGENCY, ##__VA_ARGS__); } while (0)
    #define LOG_ALERT(...)      do { util::log(util::ALERT,     ##__VA_ARGS__); } while (0)
    #define LOG_CRITICAL(...)   do { util::log(util::CRITICAL,  ##__VA_ARGS__); } while (0)
    #define LOG_ERROR(...)      do { util::log(util::ERROR,     ##__VA_ARGS__); } while (0)
    #define LOG_WARNING(...)    do { util::log(util::WARNING,   ##__VA_ARGS__); } while (0)
    #define LOG_WARN(...)       do { util::log(util::WARN,      ##__VA_ARGS__); } while (0)
    #define LOG_NOTICE(...)     do { util::log(util::NOTICE,    ##__VA_ARGS__); } while (0)
    #define LOG_INFO(...)       do { util::log(util::INFO,      ##__VA_ARGS__); } while (0)
#if defined(ENABLE_DEBUGGING)
    #define LOG_DEBUG(...)      do { util::log(util::DEBUG,     ##__VA_ARGS__); } while (0)
#else
    #define LOG_DEBUG(...)      do { ; } while (0)
#endif


    class scoped_logger : public nocopy {
        public:
            scoped_logger (const level_t, const std::string&);
            ~scoped_logger ();

        protected:
            const level_t      m_level;
            const std::string &m_message;
    };
}

#include "log.ipp"

#endif