Bypass dispatch during numeric operations. 2x speedup

include/chaiscript/language/chaiscript_common.hpp

@@ -29,7 +29,8 @@ namespace chaiscript
       const_int_flag,
       shift_left, shift_right, remainder, bitwise_and, bitwise_or, bitwise_xor, bitwise_complement,
       const_flag,
-      sum, quotient, product, difference, unary_plus, unary_minus
+      sum, quotient, product, difference, unary_plus, unary_minus, 
+      invalid
     };
 
     static const char *to_string(Opers t_oper) {
@@ -45,11 +46,86 @@ namespace chaiscript
         "", 
         "<<", ">>", "%", "&", "|", "^", "~",
         "",
-        "+", "/", "*", "-", "+", "-"
+        "+", "/", "*", "-", "+", "-",
+        ""
       };
       return opers[t_oper];
     }
 
+    static Opers to_operator(const std::string &t_str, bool t_is_unary = false)
+    {
+      if (t_str == "==")
+      {
+        return equals;
+      } else if (t_str == "<") {
+        return less_than;
+      } else if (t_str == ">") {
+        return greater_than;
+      } else if (t_str == "<=") {
+        return less_than_equal; 
+      } else if (t_str == ">=") {
+        return greater_than_equal;
+      } else if (t_str == "!=") {
+        return not_equal;
+      } else if (t_str == "=") {
+        return assign;
+      } else if (t_str == "++") {
+        return pre_increment;
+      } else if (t_str == "--") {
+        return pre_decrement;
+      } else if (t_str == "*=") {
+        return assign_product;
+      } else if (t_str == "+=") {
+        return assign_sum;
+      } else if (t_str == "-=") {
+        return assign_difference;
+      } else if (t_str == "&=") {
+        return assign_bitwise_and;
+      } else if (t_str == "|=") {
+        return assign_bitwise_or;
+      } else if (t_str == "<<=") {
+        return assign_shift_left;
+      } else if (t_str == ">>=") {
+        return assign_shift_right;
+      } else if (t_str == "%=") {
+        return assign_remainder;
+      } else if (t_str == "^=") {
+        return assign_bitwise_xor;
+      } else if (t_str == "<<") {
+        return shift_left;
+      } else if (t_str == ">>") {
+        return shift_right;
+      } else if (t_str == "%") {
+        return remainder;
+      } else if (t_str == "&") { 
+        return bitwise_and;
+      } else if (t_str == "|") {
+        return bitwise_or;
+      } else if (t_str == "^") {
+        return bitwise_xor;
+      } else if (t_str == "~") {
+        return bitwise_complement;
+      } else if (t_str == "+") {
+        if (t_is_unary) {
+          return unary_plus;
+        } else {
+          return sum;
+        }
+      } else if (t_str == "-") {
+        if (t_is_unary) {
+          return unary_minus;
+        } else {
+          return difference;
+        }
+      } else if (t_str == "/") {
+        return quotient;
+      } else if (t_str == "*") {
+        return product;
+      } else {
+        return invalid;
+      } 
+    }
+
   };
 
   /// Types of AST nodes available to the parser and eval