SymbolList.java

package ppg.atoms;

import java.util.*;

public class SymbolList
{
	public static final int TERMINAL = 0;
	public static final int NONTERMINAL = 1;
	
	private int variety;
	private String type;
	private Vector symbols;
	
	public SymbolList(int which, String type, Vector syms) {
		variety = which;
		this.type = type;
		symbols = syms;
	}	
	
	public boolean dropSymbol (String gs) {
		for (int i=0; i < symbols.size(); i++) {
			if (gs.equals(symbols.elementAt(i))) {
				symbols.removeElementAt(i);
				// assume we do not have duplicates
				return true;
			}
		}
		return false;
	}
	
	public Object clone() {
		String newType = (type == null) ? null : type.toString();
		Vector newSyms = new Vector();
		for (int i=0; i < symbols.size(); i++) {
			newSyms.addElement( ((String)symbols.elementAt(i)).toString() );
		}
		return new SymbolList(variety, newType, newSyms);
	}
	
	public String toString() {
		String result = "";

		if (symbols.size() > 0) {
			switch (variety) {
				case (TERMINAL): result = "terminal "; break;
				case (NONTERMINAL): result = "non terminal "; break;
			}
		
			if (type != null)
				result += type + " ";
		
			int size = symbols.size();
			for (int i=0; i < size; i++) {
				result += (String)symbols.elementAt(i);
				if (i < size - 1)
					result += ", ";
			}
			result += ";";
		}
		
		return result;
	}
}