add config file reader-parser

cxx/CMakeLists.txt

@@ -87,7 +87,8 @@ add_library(${CNTR_PROTO_LIB} STATIC ${CNTR_PROTO_LIB_SRC})
 
 set(MOUNT_SERVER_APP_SRC mount.h mount_server.cpp comm_server.h comm_server_endpoint.h)
 set(MOUNT_SERVER_APP mount_server)
-add_executable(${MOUNT_SERVER_APP} ${MOUNT_SERVER_APP_SRC})
+add_executable(${MOUNT_SERVER_APP} ${MOUNT_SERVER_APP_SRC}
+    comm_server_configfile.h)
 target_link_libraries(${MOUNT_SERVER_APP} ${CNTR_PROTO_LIB} spdlog::spdlog_header_only)
 
 if (WITH_TESTS)
@@ -96,4 +97,7 @@ if (WITH_TESTS)
     target_link_libraries(${CNTR_PROTO_TEST_APP} ${CNTR_PROTO_LIB} spdlog::spdlog_header_only)
     # target_link_libraries(${CNTR_PROTO_TEST_APP} ${CNTR_PROTO_LIB})
     # target_include_directories(${CNTR_PROTO_TEST_APP} PUBLIC ${SPDLOG_INCLUDE_DIRS})
+
+    set(CFGFILE_TEST_APP configfile_test)
+    add_executable(${CFGFILE_TEST_APP} tests/configfile_test.cpp)
 endif()

cxx/comm_server_configfile.h

@@ -0,0 +1,145 @@
+#pragma once
+
+/*    MOUNT CONTRO: COMPONENTS    */
+
+
+#include <concepts>
+#include <cstddef>
+#include <fstream>
+#include <unordered_map>
+#include <variant>
+
+#include "comm_server_endpoint.h"
+#include "utils.h"
+
+namespace mcc
+{
+
+
+/*
+ *  A VERY SIMPLE CONFIG-FILE READER-PARSER
+ *
+ *  format:
+ *      key = value1, value2, ...
+ *
+ *      a line beginning from '#' symbol is a comment and will be skipped
+ *      a line containing from only ' ' is skipped
+ */
+
+class MccConfigfile
+{
+public:
+    static constexpr char COMMENT_SYMBOL = '#';
+    static constexpr char KEY_VALUE_DELIM = '=';
+    static constexpr char VALUE_VALUE_DELIM = ',';
+
+
+    typedef std::unordered_map<std::string, std::variant<std::monostate, std::string, std::vector<std::string>>>
+        config_t;
+
+    template <typename T = std::nullptr_t>
+    MccConfigfile(T&& filename = nullptr)
+        requires(std::same_as<std::decay_t<T>, std::nullptr_t> || traits::mcc_input_char_range<T>)
+    {
+        if constexpr (traits::mcc_input_char_range<T>) {
+            if (load(std::forward<T>(filename))) {
+            }
+        }
+    }
+
+
+    std::error_code load(traits::mcc_input_char_range auto&& filename)
+    {
+        std::filesystem::path pt(filename.begin(), filename.end());
+
+        // first, check file existence
+
+        std::error_code ec;
+        auto pt_cn = std::filesystem::canonical(pt, ec);
+        if (ec) {
+            return ec;
+        }
+
+        std::ifstream fin(pt_cn);
+
+        if (!fin.is_open()) {
+            return std::make_error_code(std::errc::no_such_file_or_directory);
+            // return std::make_error_code(std::errc::permission_denied);
+        }
+
+        _currentFilename = pt_cn.string();
+        _currentConfig.clear();
+
+        // read line-by-line
+        for (std::string line; std::getline(fin, line);) {
+            if (line.empty()) {
+                continue;
+            }
+
+            auto sv = utils::trimSpaces(line, utils::TrimType::TRIM_LEFT);
+
+            if (sv.size()) {
+                if (sv[0] == COMMENT_SYMBOL) {  // comment string
+                    continue;
+                }
+
+                auto it = std::ranges::find(sv, KEY_VALUE_DELIM);
+                if (it == sv.begin()) {  // empty key! skip!
+                    continue;
+                }
+                auto key = utils::trimSpaces(std::string_view{sv.begin(), it}, utils::TrimType::TRIM_RIGHT);
+                std::string skey = {key.begin(), key.end()};
+
+                if (it == sv.end()) {  // only key
+                    _currentConfig[skey] = {};
+                } else {  // key and value
+                    auto vals = utils::trimSpaces(std::string_view{it + 1, sv.end()});
+                    auto it_dlm = std::ranges::find(vals, VALUE_VALUE_DELIM);
+
+                    if (it_dlm == vals.end()) {  // scalar value
+                        _currentConfig[skey] = std::string{vals.begin(), vals.end()};
+                    } else {  // vector of values
+                        std::vector<std::string> elems;
+                        while (it_dlm != vals.end()) {
+                            auto el = utils::trimSpaces(std::string_view{vals.begin(), it_dlm});
+                            elems.emplace_back(el.begin(), el.end());
+
+                            vals = {it_dlm + 1, vals.end()};
+                            it_dlm = std::ranges::find(vals, VALUE_VALUE_DELIM);
+                        }
+
+                        _currentConfig[skey] = elems;
+                    }
+                }
+            } else {  // the string contains from only spaces
+                continue;
+            }
+        }
+
+        fin.close();
+
+        return {};
+    }
+
+    std::string currentFilename() const
+    {
+        return _currentFilename;
+    }
+
+    const config_t& config() const
+    {
+        return _currentConfig;
+    }
+
+    // config_t& config()
+    // {
+    //     return _currentConfig;
+    // }
+
+private:
+    std::string _currentFilename;
+
+    config_t _currentConfig;
+};
+
+}  // namespace mcc

cxx/tests/configfile_test.cpp

@@ -0,0 +1,39 @@
+#include <iostream>
+
+#include "../comm_server_configfile.h"
+
+
+
+int main(int argc, char* argv[])
+{
+    if (argc < 2) {
+        std::cout << "Usage: " << argv[0] << " cfg_filename\n";
+        return 1;
+    }
+
+    mcc::MccConfigfile cfg;
+
+    auto ec = cfg.load(std::string_view{argv[1]});
+    if (ec) {
+        std::cout << "ERR: " << ec.message() << "\n";
+        return 1;
+    }
+
+    for (auto& [key, v] : cfg.config()) {
+        std::cout << "<" << key << "> = ";
+        if (v.index()) {
+            if (v.index() > 1) {
+                for (auto& el : std::get<2>(v)) {
+                    std::cout << "<" << el << "> ";
+                }
+                std::cout << "\n";
+            } else {
+                std::cout << "<" << std::get<1>(v) << ">\n";
+            }
+        } else {
+            std::cout << "<no value>\n";
+        }
+    }
+
+    return 0;
+}