package java_cup;
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import java.util.Enumeration;
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import java.util.Hashtable;
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/** This class represents a terminal symbol in the grammar. Each terminal
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* has a textual name, an index, and a string which indicates the type of
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* object it will be implemented with at runtime (i.e. the class of object
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* that will be returned by the scanner and pushed on the parse stack to
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* represent it).
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*
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* @version last updated: 11/25/95
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* @author Scott Hudson
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*/
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public class terminal extends symbol {
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/*-----------------------------------------------------------*/
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/*--- Constructor(s) ----------------------------------------*/
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/*-----------------------------------------------------------*/
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/** Full constructor.
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* @param nm the name of the terminal.
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* @param tp the type of the terminal.
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*/
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public terminal(String nm, String tp)
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{
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/* superclass does most of the work */
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super(nm, tp);
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/* add to set of all terminals and check for duplicates */
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Object conflict = _all.put(nm,this);
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if (conflict != null)
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// can't throw an execption here because this is used in static
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// initializers, so we do a crash instead
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// was:
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// throw new internal_error("Duplicate terminal (" + nm + ") created");
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(new internal_error("Duplicate terminal (" + nm + ") created")).crash();
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/* assign a unique index */
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_index = next_index++;
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/* add to by_index set */
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_all_by_index.put(new Integer(_index), this);
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}
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/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
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/** Constructor with default type.
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* @param nm the name of the terminal.
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*/
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public terminal(String nm)
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{
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this(nm, null);
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}
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/*-----------------------------------------------------------*/
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/*--- (Access to) Static (Class) Variables ------------------*/
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/*-----------------------------------------------------------*/
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/** Table of all terminals. Elements are stored using name strings as
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* the key
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*/
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protected static Hashtable _all = new Hashtable();
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/** Access to all terminals. */
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public static Enumeration all() {return _all.elements();};
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/** Lookup a terminal by name string. */
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public static terminal find(String with_name)
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{
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if (with_name == null)
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return null;
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else
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return (terminal)_all.get(with_name);
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}
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/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
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/** Table of all terminals indexed by their index number. */
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protected static Hashtable _all_by_index = new Hashtable();
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/** Lookup a terminal by index. */
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public static terminal find(int indx)
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{
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Integer the_indx = new Integer(indx);
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return (terminal)_all_by_index.get(the_indx);
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}
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/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
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/** Total number of terminals. */
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public static int number() {return _all.size();};
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/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
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/** Static counter to assign unique index. */
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protected static int next_index = 0;
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/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
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/** Special terminal for end of input. */
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public static final terminal EOF = new terminal("EOF");
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/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
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/** special terminal used for error recovery */
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public static final terminal error = new terminal("error");
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/*-----------------------------------------------------------*/
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/*--- General Methods ---------------------------------------*/
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/*-----------------------------------------------------------*/
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/** Report this symbol as not being a non-terminal. */
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public boolean is_non_term()
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{
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return false;
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}
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/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
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/** Convert to a string. */
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public String toString()
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{
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return super.toString() + "[" + index() + "]";
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}
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/*-----------------------------------------------------------*/
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};
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