Add support for config file.

src/options.cpp

@@ -23,7 +23,10 @@
 #include <boost/program_options/parsers.hpp>
 #include <boost/program_options/variables_map.hpp>
 
+#include <cstdlib>
+#include <fstream>
 #include <iostream>
+#include <string>
 
 namespace epubgrep
 {
@@ -53,6 +56,11 @@ po::variables_map parse_options(int argc, char *argv[])
     // clang-format on
     po::variables_map vm;
     po::store(po::parse_command_line(argc, argv, desc), vm);
+
+    std::ifstream configfile(get_config_path());
+    po::store(po::parse_config_file(configfile, desc, true), vm);
+    configfile.close();
+
     po::notify(vm);
 
     if (vm.count("help") != 0)
@@ -75,4 +83,34 @@ po::variables_map parse_options(int argc, char *argv[])
     return vm;
 }
 
+std::string get_config_path()
+{
+    auto get_env = [](std::string const &name)
+    {
+        const char *env = std::getenv(name.c_str());
+        if (env != nullptr)
+        {
+            return env;
+        }
+
+        return "";
+    };
+
+    std::string path{get_env("XDG_CONFIG_HOME")};
+    if (path.empty())
+    {
+        path = get_env("HOME");
+        if (!path.empty())
+        {
+            path += "/.config";
+        }
+    }
+    if (!path.empty())
+    {
+        path += "/";
+    }
+
+    return path += "epubgrep.conf";
+}
+
 } // namespace epubgrep

src/options.hpp

@@ -19,6 +19,8 @@
 
 #include <boost/program_options/variables_map.hpp>
 
+#include <string>
+
 namespace epubgrep
 {
 
@@ -27,6 +29,15 @@ namespace po = boost::program_options;
 //! Parse options and return them.
 po::variables_map parse_options(int argc, char *argv[]);
 
+/*!
+ *  @brief Returns the path of the config file.
+ *
+ *  Tries these paths: ${XDG_CONFIG_HOME}/epubgrep.conf
+ *                     ${HOME}/.config/epubgrep.conf
+ *                     epubgrep.conf
+ */
+std::string get_config_path();
+
 } // namespace epubgrep
 
 #endif // EPUBGREP_OPTIONS_HPP