Simple Logger

src/utility/Logger.cpp

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+/**
+ * @file Logger.cpp
+ * @author Anand Doshi
+ * @date 2025-01-08
+ *
+ * @copyright Copyright (c) 2025
+ *
+ */
+
+
+#include "Logger.hpp"
+#include <cstdio>
+#include <ctime>
+#include <iterator>
+#include <stdexcept>
+#include <string>
+#include <string_view>
+
+bool Logger::isLoggable(Level level)
+{
+    if (filter == Filter::quiet)
+    {
+        return false;
+    }
+
+    if (filter == Filter::important)
+    {
+        return level == Level::error || level == Level::warning || level == Level::severe;
+    }
+
+    if (filter == Filter::verbose)
+    {
+        return true;
+    }
+
+    return true; // unknown filter, everything logged
+}
+
+constexpr std::string_view Logger::getLevelName(Logger::Level level)
+{
+    switch (level)
+    {
+        case Logger::Level::error:
+            return "error";
+        case Logger::Level::warning:
+            return "warning";
+        case Logger::Level::severe:
+            return "severe";
+        case Logger::Level::info:
+            return "info";
+        case Logger::Level::fine:
+            return "fine";
+        default:
+            throw std::invalid_argument("Invalid Level enum.");
+    }
+}
+
+void Logger::log(Level level, std::string_view message)
+{
+    if (isLoggable(level))
+    {
+
+        std::time_t now = std::time(nullptr);
+
+        char timestamp[std::size(Logger::timestampFormat)];
+        std::strftime(timestamp, std::size(Logger::timestampFormat),
+                      "%FT%TZ", std::localtime(&now));
+        logStream << '[' << timestamp << "] " << '(' << name << ") " << '[' << getLevelName(level) << "] " << message << '\n';
+    }
+}
+
+void Logger::error(std::string_view message)
+{
+    log(Level::error, message);
+}
+
+void Logger::warning(std::string_view message)
+{
+    log(Level::warning, message);
+}
+
+void Logger::severe(std::string_view message)
+{
+    log(Level::severe, message);
+}
+
+void Logger::info(std::string_view message)
+{
+    log(Level::info, message);
+}
+
+void Logger::fine(std::string_view message)
+{
+    log(Level::fine, message);
+}

src/utility/Logger.hpp

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+/**
+ * @file Logger.hpp
+ * @author Anand Doshi
+ * @date 2025-01-08
+ *
+ * @copyright Copyright (c) 2025
+ *
+ */
+
+
+#include <iostream>
+#include <string_view>
+
+class Logger
+{
+public:
+    enum class Filter
+    {
+        quiet,
+        verbose,
+        important
+    };
+
+    enum class Level
+    {
+        error,
+        warning,
+        severe,
+        info,
+        fine,
+    };
+
+    Logger(std::string_view name)
+        : Logger{name, Filter::important, std::cout}
+    {
+    }
+
+    Logger(std::string_view name, Filter filter)
+        : Logger{name, filter, std::cout}
+    {
+    }
+
+    Logger(std::string_view name, Filter filter, std::ostream &logStream)
+        : name{name}, filter{filter}, logStream{logStream}
+    {
+    }
+
+    void setFilter(Filter filterToSet) { filter = filterToSet; }
+
+    void log(Level level, std::string_view message);
+    void error(std::string_view message);
+    void warning(std::string_view message);
+    void severe(std::string_view message);
+    void info(std::string_view message);
+    void fine(std::string_view message);
+
+private:
+    std::string name;
+    Filter filter;
+    std::ostream &logStream;
+
+    // ISO 8601 date time format
+    inline static const std::string timestampFormat{"yyyy-mm-ddThh:mm:ssZ"};
+
+    bool isLoggable(Level level);
+
+    static constexpr std::string_view getLevelName(Level level);
+};