First start plug-in architecture

src/ifcgeom/kernel_plugin.cpp

@@ -0,0 +1,85 @@
+/********************************************************************************
+ *                                                                              *
+ * This file is part of IfcOpenShell.                                           *
+ *                                                                              *
+ * IfcOpenShell is free software: you can redistribute it and/or modify         *
+ * it under the terms of the Lesser GNU General Public License as published by  *
+ * the Free Software Foundation, either version 3.0 of the License, or          *
+ * (at your option) any later version.                                          *
+ *                                                                              *
+ * IfcOpenShell 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                 *
+ * Lesser GNU General Public License for more details.                          *
+ *                                                                              *
+ * You should have received a copy of the Lesser GNU General Public License     *
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.         *
+ *                                                                              *
+ ********************************************************************************/
+
+#include "kernel_plugin.h"
+
+#ifndef _WIN32
+#include <dlfcn.h>
+#else
+#include <windows.h>
+#endif
+
+#include <stdexcept>
+
+namespace {
+	constexpr const char* kernel_plugin_prefix = "geometry.kernel.";
+}
+
+const char* ifcopenshell::geometry::kernels::kernel_plugin_registration_symbol() {
+	return "ifcopenshell_register_kernel_plugin_v1";
+}
+
+ifcopenshell::plugin::metadata ifcopenshell::geometry::kernels::kernel_plugin_metadata(const std::string& plugin_name) {
+	plugin::metadata metadata;
+	metadata.kind_ = plugin::kind::kernel;
+	metadata.id = kernel_plugin_prefix + plugin_name;
+	return metadata;
+}
+
+std::filesystem::path ifcopenshell::geometry::kernels::kernel_plugin_directory() {
+#ifdef _WIN32
+	HMODULE module_handle = nullptr;
+	if (!GetModuleHandleExW(
+		GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS | GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,
+		reinterpret_cast<LPCWSTR>(&ifcopenshell::geometry::kernels::load_kernel_plugins),
+		&module_handle)) {
+		throw std::runtime_error("Unable to resolve IfcGeom module path");
+	}
+
+	wchar_t buffer[MAX_PATH];
+	const DWORD length = GetModuleFileNameW(module_handle, buffer, MAX_PATH);
+	if (length == 0) {
+		throw std::runtime_error("Unable to read IfcGeom module filename");
+	}
+
+	return std::filesystem::path(std::wstring(buffer, length)).parent_path();
+#else
+	Dl_info info;
+	if (dladdr(reinterpret_cast<const void*>(&ifcopenshell::geometry::kernels::load_kernel_plugins), &info) == 0 || !info.dli_fname) {
+		throw std::runtime_error("Unable to resolve IfcGeom module path");
+	}
+
+	return std::filesystem::path(info.dli_fname).parent_path();
+#endif
+}
+
+void ifcopenshell::geometry::kernels::load_kernel_plugins(kernel_registry& registry) {
+	plugin::manager manager;
+	manager.add_search_path(kernel_plugin_directory());
+
+	for (const auto& path : manager.discover(kernel_plugin_prefix)) {
+		auto module = manager.load(path);
+		if (module.meta().kind_ != plugin::kind::kernel) {
+			continue;
+		}
+
+		auto register_plugin = module.get_alias<register_kernel_plugin_fn>(kernel_plugin_registration_symbol());
+		register_plugin(registry, module);
+	}
+}