feat: add universal config manager implementation.

src/ConfigManager.cpp

@@ -0,0 +1,148 @@
+#include "ConfigManager.hpp"
+
+#include "EncodingHelper.hpp"
+#include "IOHelper.hpp"
+
+namespace YYCC::ConfigManager {
+
+#pragma region Core Manager
+
+	CoreManager::CoreManager(
+		const yycc_char8_t* cfg_file_path,
+		uint64_t version_identifier,
+		std::initializer_list<AbstractSetting*> settings) :
+		m_CfgFilePath(), m_VersionIdentifier(version_identifier), m_Settings() {
+		// assign cfg path
+		if (cfg_file_path != nullptr)
+			m_CfgFilePath = cfg_file_path;
+		// assign settings
+		for (auto* setting : settings) {
+			m_Settings.try_emplace(setting->GetName(), setting);
+		}
+	}
+
+	bool CoreManager::Load() {
+		// reset all settings first
+		Reset();
+
+		// get file handle
+		auto fs = this->GetFileHandle(YYCC_U8("rb"));
+		if (fs.get() == nullptr) {
+			// if we fail to get, it means that we do not have corresponding cfg file.
+			// all settings should be reset to default value.
+			return true;
+		}
+
+		// fetch version info
+		uint64_t version_info;
+		if (std::fread(&version_info, sizeof(version_info), 1u, fs.get()) != sizeof(version_info))
+			return false;
+		// check version
+		// if read version is greater than we expected,
+		// it means that this cfg file is created by the program higer than this.
+		// we should not read anything from it.
+		// however, for compaitibility reason, we allow read old cfg data.
+		if (version_info > m_VersionIdentifier)
+			return true;
+
+		// fetch setting item from file
+		yycc_u8string name_cache;
+		while (true) {
+			// try fetch setting name
+			// fetch name length
+			size_t name_length;
+			if (std::fread(&name_length, sizeof(name_length), 1u, fs.get()) != sizeof(name_length)) {
+				// we also check whether reach EOF at there.
+				if (std::feof(fs.get())) break;
+				else return false;
+			}
+			// fetch name body
+			name_cache.resize(name_length);
+			if (std::fread(name_cache.data(), name_length, 1u, fs.get()) != name_length)
+				return false;
+
+			// get setting data length
+			size_t data_length;
+			if (std::fread(&data_length, sizeof(data_length), 1u, fs.get()) != sizeof(data_length))
+				return false;
+
+			// get matched setting first
+			const auto& found = m_Settings.find(name_cache);
+			if (found != m_Settings.end()) {
+				// found. read data for it
+				found->second->ResizeData(data_length);
+				if (std::fread(found->second->GetDataPtr(), data_length, 1u, fs.get()) != data_length)
+					return false;
+				// call user defined load function
+				// if fail to parse, reset to default value
+				if (!found->second->UserLoad())
+					found->second->UserReset();
+			} else {
+				// fail to find. skip this unknown setting
+				if (fseek(fs.get(), static_cast<long>(data_length), SEEK_CUR) != 0)
+					return false;
+			}
+		}
+
+		return true;
+	}
+
+	bool CoreManager::Save() {
+		// get file handle
+		auto fs = this->GetFileHandle(YYCC_U8("wb"));
+		// if we fail to get, return false.
+		if (fs == nullptr) return false;
+
+		// write config data
+		uint64_t version_info = m_VersionIdentifier;
+		if (std::fwrite(&version_info, sizeof(version_info), 1u, fs.get()) != sizeof(version_info))
+			return false;
+
+		// iterate all data for writing
+		for (const auto& pair : m_Settings) {
+			// do user defined save
+			// if failed, skip this setting
+			if (!pair.second->UserSave())
+				continue;
+
+			// write setting name
+			// write name length
+			size_t name_length = pair.first.size();
+			if (std::fwrite(&name_length, sizeof(name_length), 1u, fs.get()) != sizeof(name_length))
+				return false;
+			// write name body
+			if (std::fwrite(pair.first.c_str(), name_length, 1u, fs.get()) != name_length)
+				return false;
+
+			// write setting daat
+			// write data length
+			size_t data_length = pair.second->GetDataSize();
+			if (std::fwrite(&data_length, sizeof(data_length), 1u, fs.get()) != sizeof(data_length))
+				return false;
+			// write data body
+			if (std::fwrite(pair.second->GetDataPtr(), data_length, 1u, fs.get()) != data_length)
+				return false;
+		}
+
+		// all settings done, return true
+		return true;
+	}
+
+	void CoreManager::Reset() {
+		for (const auto& pair : m_Settings) {
+			pair.second->UserReset();
+		}
+	}
+
+	CoreManager::FileHandleGuard_t CoreManager::GetFileHandle(const yycc_char8_t* mode) const {
+		return CoreManager::FileHandleGuard_t(
+			IOHelper::UTF8FOpen(this->m_CfgFilePath.c_str(), mode),
+			[](FILE* fs) -> void {
+				if (fs != nullptr) std::fclose(fs);
+			}
+		);
+	}
+
+#pragma endregion
+
+}