+static inline item_number
+symbol_number_as_item_number (symbol_number sym)
+{
+ return sym;
+}
+
+static inline symbol_number
+item_number_as_symbol_number (item_number i)
+{
+ return i;
+}
+
+static inline bool
+item_number_is_symbol_number (item_number i)
+{
+ return i >= 0;
+}
+
+/* Rule numbers. */
+typedef int rule_number;
+#define RULE_NUMBER_MAX INT_MAX
+extern rule_number nrules;
+
+static inline item_number
+rule_number_as_item_number (rule_number r)
+{
+ return -1 - r;
+}
+
+static inline rule_number
+item_number_as_rule_number (item_number i)
+{
+ return -1 - i;
+}
+
+static inline bool
+item_number_is_rule_number (item_number i)
+{
+ return i < 0;
+}