Improve application manangement and create desktop entries for available app

external/xdg/xdg.cpp

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+// Copyright (C) 2015 Thomas Voß <thomas.voss.bochum@gmail.com>
+// 
+// This library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published
+// by the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// 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 General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#include <xdg.h>
+
+#include <boost/algorithm/string.hpp>
+
+#include <cstdlib>
+#include <stdexcept>
+
+namespace fs = boost::filesystem;
+
+namespace
+{
+
+fs::path throw_if_not_absolute(const fs::path& p)
+{
+    if (p.has_root_directory())
+        return p;
+
+    throw std::runtime_error{"Directores MUST be absolute."};
+}
+
+namespace env
+{
+std::string get(const std::string& key, const std::string& default_value)
+{
+    if (auto value = std::getenv(key.c_str()))
+        return value;
+    return default_value;
+}
+
+std::string get_or_throw(const std::string& key)
+{
+    if (auto value = std::getenv(key.c_str()))
+    {
+        return value;
+    }
+
+    throw std::runtime_error{key + " not set in environment"};
+}
+
+constexpr const char* xdg_data_home{"XDG_DATA_HOME"};
+constexpr const char* xdg_data_dirs{"XDG_DATA_DIRS"};
+constexpr const char* xdg_config_home{"XDG_CONFIG_HOME"};
+constexpr const char* xdg_config_dirs{"XDG_CONFIG_DIRS"};
+constexpr const char* xdg_cache_home{"XDG_CACHE_HOME"};
+constexpr const char* xdg_runtime_dir{"XDG_RUNTIME_DIR"};
+}
+
+namespace impl
+{
+class BaseDirSpecification : public xdg::BaseDirSpecification
+{
+public:
+    static const BaseDirSpecification& instance()
+    {
+        static const BaseDirSpecification spec;
+        return spec;
+    }
+
+    BaseDirSpecification()
+    {
+    }
+
+    const xdg::Data& data() const override
+    {
+        return data_;
+    }
+
+    const xdg::Config& config() const override
+    {
+        return config_;
+    }
+
+    const xdg::Cache& cache() const override
+    {
+        return cache_;
+    }
+
+    const xdg::Runtime& runtime() const override
+    {
+        return runtime_;
+    }
+
+private:
+    xdg::Data data_;
+    xdg::Config config_;
+    xdg::Cache cache_;
+    xdg::Runtime runtime_;
+};
+}
+}
+
+fs::path xdg::Data::home() const
+{
+    auto v = env::get(env::xdg_data_home, "");
+    if (v.empty())
+        return throw_if_not_absolute(fs::path{env::get_or_throw("HOME")} / ".local" / "share");
+
+    return throw_if_not_absolute(fs::path(v));
+}
+
+std::vector<fs::path> xdg::Data::dirs() const
+{
+    auto v = env::get(env::xdg_data_dirs, "");
+    if (v.empty())
+        return {fs::path{"/usr/local/share"}, fs::path{"/usr/share"}};
+
+    std::vector<std::string> tokens;
+    tokens = boost::split(tokens, v, boost::is_any_of(":"));
+    std::vector<fs::path> result;
+    for (const auto& token : tokens)
+    {
+        result.push_back(throw_if_not_absolute(fs::path(token)));
+    }
+    return result;
+}
+
+fs::path xdg::Config::home() const
+{
+    auto v = env::get(env::xdg_config_home, "");
+    if (v.empty())
+        return throw_if_not_absolute(fs::path{env::get_or_throw("HOME")} / ".config");
+
+    return throw_if_not_absolute(fs::path(v));
+}
+
+std::vector<fs::path> xdg::Config::dirs() const
+{
+    auto v = env::get(env::xdg_config_dirs, "");
+    if (v.empty())
+        return {fs::path{"/etc/xdg"}};
+
+    std::vector<std::string> tokens;
+    tokens = boost::split(tokens, v, boost::is_any_of(":"));
+    std::vector<fs::path> result;
+    for (const auto& token : tokens)
+    {
+        fs::path p(token);
+        result.push_back(throw_if_not_absolute(p));
+    }
+    return result;
+}
+
+fs::path xdg::Cache::home() const
+{
+    auto v = env::get(env::xdg_cache_home, "");
+    if (v.empty())
+        return throw_if_not_absolute(fs::path{env::get_or_throw("HOME")} / ".cache");
+
+    return throw_if_not_absolute(fs::path(v));
+}
+
+fs::path xdg::Runtime::dir() const
+{
+    auto v = env::get(env::xdg_config_home, "");
+    if (v.empty())
+    {
+        // We do not fall back gracefully and instead throw, dispatching to calling
+        // code for handling the case of a safe user-specfic runtime directory missing.
+        throw std::runtime_error{"Runtime directory not set"};
+    }
+
+    return throw_if_not_absolute(fs::path(v));
+}
+
+std::shared_ptr<xdg::BaseDirSpecification> xdg::BaseDirSpecification::create()
+{
+    return std::make_shared<impl::BaseDirSpecification>();
+}
+
+const xdg::Data& xdg::data()
+{
+    return impl::BaseDirSpecification::instance().data();
+}
+
+const xdg::Config& xdg::config()
+{
+    return impl::BaseDirSpecification::instance().config();
+}
+
+const xdg::Cache& xdg::cache()
+{
+    return impl::BaseDirSpecification::instance().cache();
+}
+
+const xdg::Runtime& xdg::runtime()
+{
+    return impl::BaseDirSpecification::instance().runtime();
+}