Use regex to remove units

src/visitors/cvode_visitor.cpp

@@ -13,6 +13,7 @@
 #include "utils/logger.hpp"
 #include "visitors/visitor_utils.hpp"
 #include <optional>
+#include <regex>
 #include <utility>
 
 namespace pywrap = nmodl::pybind_wrappers;
@@ -35,6 +36,22 @@ static void remove_conserve_statements(ast::StatementBlock& node) {
     }
 }
 
+// remove units using state-of-the-art technology
+static void remove_units(ast::BinaryExpression& node) {
+    std::regex unit_pattern(R"((\d*\.?\d+)\([a-zA-Z]+\))");
+    auto rhs_string = to_nmodl(node.get_rhs());
+    auto rhs_string_no_units = fmt::format("{} = {}",
+                                           to_nmodl(node.get_lhs()),
+                                           std::regex_replace(rhs_string, unit_pattern, "$1"));
+    logger->debug("CvodeVisitor :: removing units from statement {}", to_nmodl(node));
+    logger->debug("CvodeVisitor :: result: {}", rhs_string_no_units);
+    auto expr_statement = std::dynamic_pointer_cast<ast::ExpressionStatement>(
+        create_statement(rhs_string_no_units));
+    const auto bin_expr = std::dynamic_pointer_cast<const ast::BinaryExpression>(
+        expr_statement->get_expression());
+    node.set_rhs(std::shared_ptr<ast::Expression>(bin_expr->get_rhs()->clone()));
+}
+
 static std::pair<std::string, std::optional<int>> parse_independent_var(
     std::shared_ptr<ast::Identifier> node) {
     auto variable = std::make_pair(node->get_node_name(), std::optional<int>());
@@ -152,7 +169,10 @@ class StiffVisitor: public CvodeHelperVisitor {
             program_symtab->insert(symbol);
         }
 
+        remove_units(node);
+
         auto rhs = node.get_rhs();
+
         // all indexed variables (need special treatment in SymPy)
         auto indexed_variables = get_indexed_variables(*rhs, name->get_node_name());
         auto diff2c = pywrap::EmbeddedPythonLoader::get_instance().api().diff2c;