fix getClassName for compiled files (#24)

Author: StephenSmith25

pythonfmu3/pythonfmu-export/src/pythonfmu/PySlaveInstance.cpp

@@ -24,19 +24,55 @@ inline std::string getline(const std::string& fileName)
     return line;
 }
 
-inline std::string findClassName(const std::string& fileName)
-{
-    std::string line;
-    std::ifstream infile(fileName);
-    std::string regexStr(R"(^class (\w+)\(\s*Fmi3Slave\s*\)\s*:)");
-    while (getline(infile, line)) {
-        std::smatch m;
-        std::regex re(regexStr);
-        if (std::regex_search(line, m, re)) {
-            return m[1];
+std::string getClassName(PyObject * pModule)
+{
+    std::string className = "";
+    PyObject* dict = PyModule_GetDict(pModule);
+    PyObject* keys = PyDict_Keys(dict);
+    // Iterate through the dictionary keys to find classes derived from Fmi3Slave
+    for (int i = 0; i < PyList_Size(keys); i++) {
+        PyObject* key = PyList_GetItem(keys, i);
+        if (PyUnicode_Check(key)) {
+        PyObject* utf8Str = PyUnicode_AsEncodedString(key, "utf-8", nullptr);
+        if (utf8Str == nullptr) {
+            return "";
+        }
+        std::string classNameCandidate = PyBytes_AsString(utf8Str);
+        Py_DECREF(utf8Str);
+
+        // Check if the class is a subclass of Fmi3Slave
+        PyObject* obj = PyDict_GetItem(dict, key);
+        if (PyObject_HasAttrString(obj, "__bases__")) {
+            PyObject* bases = PyObject_GetAttrString(obj, "__bases__");
+            if (PyTuple_Check(bases)) {
+            for (int j = 0; j < PyTuple_Size(bases); j++) {
+                PyObject* base = PyTuple_GetItem(bases, j);
+                PyObject* baseNameObj = PyObject_GetAttrString(base, "__name__");
+                if (baseNameObj && PyUnicode_Check(baseNameObj)) {
+                PyObject* baseUtf8Str = PyUnicode_AsEncodedString(baseNameObj, "utf-8", nullptr);
+                if (baseUtf8Str != nullptr) {
+                    std::string baseName = PyBytes_AsString(baseUtf8Str);
+                    Py_DECREF(baseUtf8Str);
+                    if (baseName == "Fmi3Slave") {
+                    className = classNameCandidate;
+                    Py_DECREF(baseNameObj);
+                    Py_DECREF(bases);
+                    break;
+                    }
+                }
+                Py_DECREF(baseNameObj);
+                }
+            }
+            }
+            Py_DECREF(bases);
+        }
+
+        if (!className.empty()) {
+            break; // Break after finding the first subclass
+        }
         }
     }
-    return "";
+    return className;
 }
 
 inline void py_safe_run(const std::function<void(PyGILState_STATE gilState)>& f)
@@ -77,7 +113,7 @@ PySlaveInstance::PySlaveInstance(std::string instanceName, std::string resources
             handle_py_exception("[ctor] PyImport_ImportModule", gilState);
         }
 
-        std::string className = findClassName(resources_ + "/" + moduleName + ".py");
+        std::string className = getClassName(pModule);
         if (className.empty()) {
             cleanPyObject();
             throw cppfmu::FatalError("Unable to find class extending Fmi3Slave!");