fix: Add NFA node for 0 repetition case to prevent incorrectly terminating.

src/log_surgeon/finite_automata/DeterminizationConfiguration.hpp

@@ -81,6 +81,16 @@ class DeterminizationConfiguration {
         return m_lookahead < rhs.m_lookahead;
     }
 
+    auto child_configuration_with_new_state(TypedNfaState const* new_nfa_state
+    ) const -> DeterminizationConfiguration {
+        return DeterminizationConfiguration(
+                new_nfa_state,
+                m_tag_id_to_reg_ids,
+                m_history,
+                m_lookahead
+        );
+    }
+
     /**
      * Creates a new configuration from the current configuration by replacing the NFA state and
      * appending a future tag operation.
@@ -161,15 +171,16 @@ auto DeterminizationConfiguration<TypedNfaState>::update_reachable_configs(
         std::stack<DeterminizationConfiguration>& unexplored_stack
 ) const -> void {
     for (auto const& nfa_spontaneous_transition : m_nfa_state->get_spontaneous_transitions()) {
-        auto parent_config{*this};
+        auto child_config{this->child_configuration_with_new_state(
+                nfa_spontaneous_transition.get_dest_state()
+        )};
         for (auto const tag_op : nfa_spontaneous_transition.get_tag_ops()) {
-            auto child_config{parent_config.child_configuration_with_new_state_and_tag(
+            child_config = child_config.child_configuration_with_new_state_and_tag(
                     nfa_spontaneous_transition.get_dest_state(),
                     tag_op
-            )};
-            parent_config = child_config;
+            );
         }
-        unexplored_stack.push(parent_config);
+        unexplored_stack.push(child_config);
     }
 }
 

tests/test-dfa.cpp

@@ -142,7 +142,7 @@ TEST_CASE("Test Complex Tagged DFA", "[DFA]") {
     test_dfa({var_schema}, expected_serialized_dfa);
 }
 
-TEST_CASE("Test Repetition Tagged DFA", "[DFA]") {
+TEST_CASE("Test multi-valued tag in tagged DFA", "[DFA]") {
     string const var_schema{"capture:([a]+=(?<val>1+),)+"};
     string const expected_serialized_dfa{
             "0:byte_transitions={a-()->1}\n"
@@ -156,3 +156,16 @@ TEST_CASE("Test Repetition Tagged DFA", "[DFA]") {
     };
     test_dfa({var_schema}, expected_serialized_dfa);
 }
+
+TEST_CASE("Test integer DFA", "[DFA]") {
+    string const var_schema{"int:\\-{0,1}\\d+"};
+    string const expected_serialized_dfa{
+            "0:byte_transitions={--()->1,0-()->2,1-()->2,2-()->2,3-()->2,4-()->2,5-()->2,6-()->2,7-"
+            "()->2,8-()->2,9-()->2}\n"
+            "1:byte_transitions={0-()->2,1-()->2,2-()->2,3-()->2,4-()->2,5-()->2,6-()->2,7-()->2,8-"
+            "()->2,9-()->2}\n"
+            "2:accepting_tags={0},accepting_operations={},byte_transitions={0-()->2,1-()->2,2-()->"
+            "2,3-()->2,4-()->2,5-()->2,6-()->2,7-()->2,8-()->2,9-()->2}\n"
+    };
+    test_dfa({var_schema}, expected_serialized_dfa);
+}