add option to drop parens from node symbol string

include/spark_dsg/node_symbol.h

@@ -80,7 +80,7 @@ class NodeSymbol {
   [[deprecated("use str() instead")]] std::string getLabel() const;
 
   //! get a string representation of the symbol
-  std::string str() const;
+  std::string str(bool literal = false) const;
 
   /**
    * @brief output node symbol information

python/bindings/src/spark_dsg_bindings.cpp

@@ -181,7 +181,7 @@ PYBIND11_MODULE(_dsg_bindings, module) {
           "value",
           [](const NodeSymbol& symbol) { return static_cast<NodeId>(symbol); },
           nullptr)
-      .def("__repr__", &NodeSymbol::str)
+      .def("__repr__", [](const NodeSymbol& ns) { return ns.str(false); })
       .def("__hash__",
            [](const NodeSymbol& symbol) { return static_cast<NodeId>(symbol); })
       .def(pybind11::self == pybind11::self)

src/node_symbol.cpp

@@ -63,7 +63,12 @@ NodeSymbol NodeSymbol::operator++(int) {
   return old;
 }
 
-std::string NodeSymbol::str() const {
+std::string NodeSymbol::str(bool literal) const {
+  if (literal) {
+    const auto idx = std::to_string(value_.symbol.index);
+    return std::isalpha(value_.symbol.key) ? value_.symbol.key + idx : idx;
+  }
+
   std::stringstream ss;
   ss << *this;
   return ss.str();