Add logger.

CMakeLists.txt

@@ -24,7 +24,7 @@ include(cmake/debug_flags.cmake)
 
 # All dependencies except test dependencies.
 set(CMAKE_FIND_PACKAGE_PREFER_CONFIG TRUE)
-find_package(Boost 1.65.0 REQUIRED COMPONENTS locale program_options regex)
+find_package(Boost 1.65.0 REQUIRED COMPONENTS locale log program_options regex)
 find_package(Gettext REQUIRED)
 find_package(Filesystem REQUIRED COMPONENTS Final Experimental)
 find_package(LibArchive 3.2 REQUIRED)

src/CMakeLists.txt

@@ -17,7 +17,9 @@ unset(headers_src)
 
 target_link_libraries(${PROJECT_NAME}_lib
   PUBLIC
+  Boost::dynamic_linking
   Boost::locale
+  Boost::log
   Boost::program_options
   Boost::regex
   std::filesystem

src/helpers.cpp

@@ -182,4 +182,15 @@ std::string unescape_html(const std::string_view html)
     return output;
 }
 
+std::string_view get_env(const std::string_view name)
+{
+    const char *env = std::getenv(name.data());
+    if (env != nullptr)
+    {
+        return env;
+    }
+
+    return {};
+}
+
 } // namespace epubgrep::helpers

src/helpers.hpp

@@ -15,6 +15,9 @@ namespace epubgrep::helpers
 //! Un-escape &,   and so on.
 [[nodiscard]] std::string unescape_html(std::string_view html);
 
+//! Returns environment variable or an empty string_view.
+[[nodiscard]] std::string_view get_env(std::string_view name);
+
 } // namespace epubgrep::helpers
 
 #endif // EPUBGREP_HELPERS_HPP

src/log.cpp

@@ -0,0 +1,77 @@
+/*  This file is part of epubgrep.
+ *  Copyright © 2021 tastytea <tastytea@tastytea.de>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as published by
+ *  the Free Software Foundation, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "log.hpp"
+
+#include "fs-compat.hpp"
+#include "helpers.hpp"
+
+#include <boost/locale/message.hpp>
+#include <boost/log/core.hpp>
+#include <boost/log/sources/logger.hpp>
+#include <boost/log/trivial.hpp>
+#include <boost/log/utility/setup/common_attributes.hpp>
+#include <boost/log/utility/setup/console.hpp>
+#include <boost/log/utility/setup/file.hpp>
+
+#include <iostream>
+
+namespace epubgrep::log
+{
+
+using sev = boost::log::trivial::severity_level;
+
+void init()
+{
+    namespace keywords = boost::log::keywords;
+
+    using boost::locale::translate;
+
+    const auto log_path{[]
+                        {
+                            fs::path path{helpers::get_env("XDG_STATE_HOME")};
+                            if (path.empty())
+                            {
+                                path = helpers::get_env("HOME");
+                                if (!path.empty())
+                                {
+                                    path /= ".local/state";
+                                }
+                            }
+                            if (!path.empty())
+                            {
+                                return path /= "epubgrep.log";
+                            }
+                            return fs::path{};
+                        }()};
+
+    boost::log::add_file_log(keywords::file_name = log_path.c_str(),
+                             keywords::format =
+                                 "%LineID% [%TimeStamp%] "
+                                 "[%ThreadID%]: [%Severity%] %Message%");
+    boost::log::add_console_log(std::cerr,
+                                keywords::format = translate("WARNING").str()
+                                                   + ": %Message%")
+        ->set_filter(boost::log::trivial::severity == sev::warning);
+    boost::log::add_console_log(std::cerr,
+                                keywords::format = translate("ERROR").str()
+                                                   + ": %Message%")
+        ->set_filter(boost::log::trivial::severity == sev::error);
+
+    boost::log::add_common_attributes();
+}
+
+} // namespace epubgrep::log

src/log.hpp

@@ -0,0 +1,38 @@
+/*  This file is part of epubgrep.
+ *  Copyright © 2021 tastytea <tastytea@tastytea.de>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as published by
+ *  the Free Software Foundation, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef EPUBGREP_LOG_HPP
+#define EPUBGREP_LOG_HPP
+
+#include <boost/log/sources/global_logger_storage.hpp>
+#include <boost/log/sources/logger.hpp>
+#include <boost/log/trivial.hpp>
+
+#define LOG BOOST_LOG_SEV
+
+namespace epubgrep::log
+{
+
+using sev = boost::log::trivial::severity_level;
+
+BOOST_LOG_INLINE_GLOBAL_LOGGER_DEFAULT(
+    logger, boost::log::sources::severity_logger_mt<sev>)
+
+void init();
+
+} // namespace epubgrep::log
+
+#endif // EPUBGREP_LOG_HPP

src/options.cpp

@@ -17,6 +17,7 @@
 #include "options.hpp"
 
 #include "fs-compat.hpp"
+#include "helpers.hpp"
 #include "version.hpp"
 
 #include <boost/locale/message.hpp>
@@ -149,21 +150,10 @@ options parse_options(int argc, char *argv[])
 
 fs::path get_config_path()
 {
-    const auto get_env{[](const std::string &name)
-                       {
-                           const char *env = std::getenv(name.c_str());
-                           if (env != nullptr)
-                           {
-                               return env;
-                           }
-
-                           return "";
-                       }};
-
-    fs::path path{get_env("XDG_CONFIG_HOME")};
+    fs::path path{helpers::get_env("XDG_CONFIG_HOME")};
     if (path.empty())
     {
-        path = get_env("HOME");
+        path = helpers::get_env("HOME");
         if (!path.empty())
         {
             path /= ".config";