Fix comparison of integers of different signs

include/symbol_table.hpp

@@ -21,17 +21,17 @@ struct symbol_table {
         st_{{EOL_, {TERMINAL, EOL_}}, {EPSILON_, {TERMINAL, EPSILON_}}};
 
     /// @brief Token types, mapping each symbol to a unique integer ID.
-    inline static std::unordered_map<std::string, int> token_types_{{EOL_, 1}};
+    inline static std::unordered_map<std::string, unsigned long> token_types_{{EOL_, 1}};
 
     /// @brief Reverse mapping from integer token IDs back to symbols.
-    inline static std::unordered_map<int, std::string> token_types_r_{
+    inline static std::unordered_map<unsigned long, std::string> token_types_r_{
         {1, EOL_}};
 
     /// @brief Tracks insertion order of token types.
-    inline static std::vector<int> order_{1};
+    inline static std::vector<unsigned long> order_{1};
 
     /// @brief Current index for assigning new token IDs, starting from 2.
-    inline static int i_{2};
+    inline static unsigned long i_{2};
 
     /**
      * @brief Adds a terminal symbol with its associated regex to the symbol

src/lexer.cpp

@@ -16,7 +16,7 @@ lexer::lexer(std::string filename)
 }
 
 template <typename Lexer> lexer::parse_input<Lexer>::parse_input() {
-    int         i{1};
+    unsigned long         i{1};
     std::string token_type{symbol_table::token_types_r_.at(i)};
     this->self.add("\\" + symbol_table::EOL_, i);
     ++i;