import java.io.*;
import java.util.ArrayList;

public class RecursiveDescent {

public RecursiveDescent() {
	super();

}
/** expr--> term+expr
	expr--> term
*/
static boolean expr() throws Exception {
	int savePointer = pointer;
	if (term() && nextToken().sym == Calc2Symbol.PLUS && expr()) {
		System.out.println("      expr-->term + expr");
		return true;
	}
	pointer = savePointer;
	if (term()) {
		System.out.println("      expr-->term");
		return true;
	}
	pointer = savePointer;
	return false;
}


public static void main(String[] args) throws Exception {
	//construct the token array
	Calc3Scanner scanner = new Calc3Scanner(new FileInputStream(new File("calc2.input")));
	// note that yylex() is the default method to get the next token in scanner that is generated by JLlex.
	Symbol token; 
	while ((token=scanner.yylex()).sym!= Calc2Symbol.EOF) {
		System.out.print("<"+token.toString()+ ">");  // check that all the symbols are read in correctly.
		tokens.add(token);
	}
	tokens.add(token);   // add EOF as the last token in the array
	boolean legal= program() && nextToken().sym==Calc2Symbol.EOF;
	System.out.println(legal);
}
/**  program-->statement program
	 program-->statement
*/
static boolean program() throws Exception{
	int savePointer = pointer;

	if (statement() && program()) {
			System.out.println("      program-->statement program");
			return true;
		}
	pointer = savePointer;
	if (statement()) {
		System.out.println("      program-->statement");
		return true;
	}
	pointer = savePointer;
	return false;

}

static boolean statement() throws Exception {
	int savePointer = pointer;
	pointer = savePointer;
	if (assignment() && nextToken().sym == Calc2Symbol.SEMI) {
		System.out.println("      statement-->assignment;");
		return true;
	}
	pointer = savePointer;
	return false;
}

static int pointer = -1;	
static ArrayList tokens = new ArrayList();

/**     assignment--> ID=exp
*/
static boolean  assignment () throws Exception{
		int savePointer= pointer;
		if (nextToken().sym==Calc2Symbol.ID && nextToken().sym==Calc2Symbol.EQUAL && expr()) {
			   System.out.println("      assignment--> ID=exp");
			   return true;
		}
		pointer = savePointer;
		return false;
	}

	/** exprList --> expr exprList | empty
	*/

	static boolean exprList() throws Exception {
	    int savedPointer=pointer;
	    if (expr() && exprList()) return true;
	    pointer = savedPointer;
	    return true;
	}/** factor --> ID | NUMBER | functionCall | (Expr)
*/
static boolean factor() throws Exception{
	int savePointer = pointer;
	if (functionCall()) {
		System.out.println("factor --> functionCall");
		return true;
	}
	pointer=savePointer;
	int sym=nextToken().sym;
	if (sym == Calc2Symbol.ID || 
		 sym == Calc2Symbol.NUMBER) {
		System.out.println("      factor-->ID | NUMBER");
		return true;
	}
	pointer = savePointer;
	if (nextToken().sym==Calc2Symbol.LPAREN && expr() && nextToken().sym==Calc2Symbol.RPAREN) return true;
	pointer = savePointer;
	return false;
}

	/** functionCall-->ID(exprList)
	*/
	static boolean functionCall() throws Exception  {
		int savePointer = pointer;
		if (nextToken().sym == Calc2Symbol.ID
			&& nextToken().sym == Calc2Symbol.LPAREN
			&& exprList()
			&& nextToken().sym == Calc2Symbol.RPAREN)
			return true;
		pointer = savePointer;
		return false;
	}

static Symbol nextToken() {
	if (pointer < tokens.size()-1) {
		pointer++;
		Symbol token = (Symbol) tokens.get(pointer);
		System.out.println ("next Token: " + token.toString());
		return token;
	} else
		return null;
}

/** term --> factor * term
	term --> factor
	*/
static boolean term() throws Exception {
	int savePointer = pointer;
	if (factor() && nextToken().sym == Calc2Symbol.MULTI && term()) {
		System.out.println("      term-->factor * term");
		return true;
	}
	pointer = savePointer;
	if (factor()) {
		System.out.println("      term-->factor");
		return true;
	}
	pointer = savePointer;
	return false;
}}