+++ /dev/null
-package java_cup;
-
-/** This abstract class serves as the base class for grammar symbols (i.e.,
- * both terminals and non-terminals). Each symbol has a name string, and
- * a string giving the type of object that the symbol will be represented by
- * on the runtime parse stack. In addition, each symbol maintains a use count
- * in order to detect symbols that are declared but never used, and an index
- * number that indicates where it appears in parse tables (index numbers are
- * unique within terminals or non terminals, but not across both).
- *
- * @see java_cup.terminal
- * @see java_cup.non_terminal
- * @version last updated: 7/3/96
- * @author Frank Flannery
- */
-public abstract class symbol {
- /*-----------------------------------------------------------*/
- /*--- Constructor(s) ----------------------------------------*/
- /*-----------------------------------------------------------*/
-
- /** Full constructor.
- * @param nm the name of the symbol.
- * @param tp a string with the type name.
- */
- public symbol(String nm, String tp)
- {
- /* sanity check */
- if (nm == null) nm = "";
-
- /* apply default if no type given */
- if (tp == null) tp = "Object";
-
- _name = nm;
- _stack_type = tp;
- }
-
- /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
-
- /** Constructor with default type.
- * @param nm the name of the symbol.
- */
- public symbol(String nm)
- {
- this(nm, null);
- }
-
- /*-----------------------------------------------------------*/
- /*--- (Access to) Instance Variables ------------------------*/
- /*-----------------------------------------------------------*/
-
- /** String for the human readable name of the symbol. */
- protected String _name;
-
- /** String for the human readable name of the symbol. */
- public String name() {return _name;}
-
- /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
-
- /** String for the type of object used for the symbol on the parse stack. */
- protected String _stack_type;
-
- /** String for the type of object used for the symbol on the parse stack. */
- public String stack_type() {return _stack_type;}
-
- /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
-
- /** Count of how many times the symbol appears in productions. */
- protected int _use_count = 0;
-
- /** Count of how many times the symbol appears in productions. */
- public int use_count() {return _use_count;}
-
- /** Increment the use count. */
- public void note_use() {_use_count++;}
-
- /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
-
- /** Index of this symbol (terminal or non terminal) in the parse tables.
- * Note: indexes are unique among terminals and unique among non terminals,
- * however, a terminal may have the same index as a non-terminal, etc.
- */
- protected int _index;
-
- /** Index of this symbol (terminal or non terminal) in the parse tables.
- * Note: indexes are unique among terminals and unique among non terminals,
- * however, a terminal may have the same index as a non-terminal, etc.
- */
- public int index() {return _index;}
-
- /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
-
- /** Indicate if this is a non-terminal. Here in the base class we
- * don't know, so this is abstract.
- */
- public abstract boolean is_non_term();
-
- /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
-
- /** Convert to a string. */
- public String toString()
- {
- return name();
- }
-
- /*-----------------------------------------------------------*/
-
-}