Filter.h

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#pragma once
 
#include "LogLevel.h"
 
#include <cassert>
#include <iostream>
#include <map>
#include <string>
 
namespace carl::logging {
 
/**
 * This class checks if some log message shall be forwarded to some sink.
 */
class Filter {
    /// Mapping from channels to (minimal) log levels.
    std::map<std::string, LogLevel> mData = {
        std::make_pair(std::string(""), LogLevel::LVL_DEFAULT)
    };
public:
    /**
     * Returns the internal filter data.
     */
    const auto& data() const {
        return mData;
    }
    /**
     * Set the minimum log level for some channel.
     * Returns `*this`, hence calls to this method can be chained arbitrarily.
     * @param channel Channel name.
     * @param level LogLevel.
     * @return This object.
     */
    Filter& operator()(const std::string& channel, LogLevel level) {
        mData[channel] = level;
        return *this;
    }
    /**
     * Checks if the given log level is sufficient for the log message to be forwarded.
     * @param channel Channel name.
     * @param level LogLevel.
     * @return If the message shall be forwarded.
     */
    bool check(const std::string& channel, LogLevel level) const noexcept {
        auto tmp = channel;
        auto it = mData.find(tmp);
        while (!tmp.empty() && it == mData.end()) {
            auto n = tmp.rfind('.');
            tmp = (n == std::string::npos) ? "" : tmp.substr(0, n);
            it = mData.find(tmp);
        }
        if (it == mData.end()) {
            std::cout << "Did not find something for \"" << channel << "\"" << std::endl;
            return true;
        }
        assert(it != mData.end());
        return level >= it->second;
    }
    /**
     * Streaming operator for a Filter.
     * All the rules stored in the filter are printed in a human-readable fashion.
     * @param os Output stream.
     * @param f Filter.
     * @return os.
     */
    friend std::ostream& operator<<(std::ostream& os, const Filter& f) {
        os << "Filter:" << std::endl;
        for (const auto& it: f.mData) {
            os << "\t\"" << it.first << "\" -> " << it.second << std::endl;
        }
        return os;
    }
};
 
}