Update Cppyy::GetScope to handle nested namespaces and templates

Author: Vipul-Cariappa

clingwrapper/src/clingwrapper.cxx

@@ -571,7 +571,32 @@ Cppyy::TCppScope_t Cppyy::GetScope(const std::string& name,
                                  + name + "'\n");
 #endif // NDEBUG
 
-    return Cpp::GetScope(name, parent_scope);
+    Cppyy::TCppScope_t scope = Cpp::GetScope(name, parent_scope);
+    if (!scope && (parent_scope == nullptr || parent_scope == Cpp::GetGlobalScope()))
+        scope = Cpp::GetScopeFromCompleteName(name);
+    if (scope)
+        return scope;
+
+    if (name.find('<') != std::string::npos) {
+        // Templated Type; May need instantiation
+        size_t start = name.find('<');
+        size_t end = name.rfind('>');
+        std::string params = name.substr(start + 1, end - start - 1);
+
+        std::string pure_name = name.substr(0, start);
+        scope = Cpp::GetScope(pure_name, parent_scope);
+        if (!scope && (parent_scope == nullptr || parent_scope == Cpp::GetGlobalScope()))
+            scope = Cpp::GetScopeFromCompleteName(pure_name);
+        if (!scope)
+            return nullptr;
+        
+        if (Cppyy::IsTemplate(scope)) {
+            std::vector<Cpp::TemplateArgInfo> templ_params;
+            if (!Cppyy::AppendTypesSlow(params, templ_params))
+                return Cpp::InstantiateTemplate(scope, templ_params.data(), templ_params.size());
+        }
+    }
+    return nullptr;
 }
 
 Cppyy::TCppScope_t Cppyy::GetFullScope(const std::string& name)