gistfile1.txt

package p1;
 
import java.util.ArrayList;

public class Parser {
	
	private static  int index = 0;
	private static Token token;
	private static ArrayList<Token> tokens = testTokens();
	
	public static ArrayList<Token> testTokens(){
		
		ArrayList<Token> token = new ArrayList<Token>();
		
		Token a1 = new Token(Token.TokenCode.ID, "var");
		Token a2 = new Token(Token.TokenCode.ASSIGN, "=");
		Token a3 = new Token(Token.TokenCode.INT, "3");
		Token a4 = new Token(Token.TokenCode.SEMICOL, ";");
		Token a5 = new Token(Token.TokenCode.ID, "b");
		Token a6 = new Token(Token.TokenCode.ASSIGN, "=");
		Token a7 = new Token(Token.TokenCode.INT, "4");
		Token a8 = new Token(Token.TokenCode.MULT, "*");
		Token a9 = new Token(Token.TokenCode.LPAREN, "(");
		Token a10 = new Token(Token.TokenCode.INT, "7");
		Token a11 = new Token(Token.TokenCode.MINUS, "-");
		Token a12 = new Token(Token.TokenCode.ID, "var");
		Token a13 = new Token(Token.TokenCode.RPAREN, ")");
		Token a14 = new Token(Token.TokenCode.SEMICOL, ";");
		Token a15 = new Token(Token.TokenCode.PRINT, "print");
		Token a16 = new Token(Token.TokenCode.SEMICOL, ";");
		Token a17 = new Token(Token.TokenCode.END, "end");
		
		
//		Token a1 = new Token(Token.TokenCode.INT, "3");
//		Token a2 = new Token(Token.TokenCode.ASSIGN, "=");
//		Token a3 = new Token(Token.TokenCode.ID, "var");
//		Token a4 = new Token(Token.TokenCode.INT, "4");
//		Token a5 = new Token(Token.TokenCode.SEMICOL, ";");
//		Token a17 = new Token(Token.TokenCode.END, "end");	
		
		token.add(a1);
		token.add(a2);
		token.add(a3);
		token.add(a4);
		token.add(a5);
		token.add(a6);
		token.add(a7);
		token.add(a8);
		token.add(a10);
		token.add(a11);
		token.add(a12);
		token.add(a13);
		token.add(a14);
		token.add(a15);
		token.add(a16);
		token.add(a17);
		
		return token;
	}
	
	private static void ParserError() {
		System.out.println ("Syntax error!");
		System.exit(0);
	}
	
	private static Token nextToken() {
		
		ArrayList<Token> myToken = tokens;
		Token t = myToken.get(index);
		
		if(index < myToken.size() - 1) {
			index++;
		}
		return t;
	}
 
	public static void parse() {
		token = nextToken();
		 System.out.println(" THIS IS A NEW GUY --> "+ token.code + " " + token.data);
		// if the nextToken has TokenCode ERROR
		if(token.code == Token.TokenCode.ERROR) {
			ParserError();
		}
		
		if(token.code == Token.TokenCode.END){
			//the end
			System.out.println("THE END");
		}
		
		if(token.code == Token.TokenCode.SEMICOL) {
			token = nextToken();
			System.out.println("printing semicol");
			parse();
		}
		else {
			Statement();
			parse();
		}
	}
	public static void Statement(){
		// if the nextToken has TokenCode ERROR
		if(token.code == Token.TokenCode.ERROR) {
			ParserError();				
		}
		
		if(token.code == Token.TokenCode.PRINT){
			token = nextToken();
			// if erroor...
			System.out.println("PRINT " + token.data);
		}
		
		if(token.code == Token.TokenCode.ID) {
			//Factor();
			Expr();
			token = nextToken();
			if(token.code == Token.TokenCode.ASSIGN) {
				token = nextToken();
				Expr();
				System.out.println("ASSIGN");
				System.out.println(token.code + token.data);
				// token = nextToken();
			}
			else {
				// handle var INT ....
				ParserError();
			}
		}
		if(token.code == Token.TokenCode.SEMICOL) {
			//do nothing
		}
		
		else if(token.code != Token.TokenCode.ID || token.code != Token.TokenCode.PRINT){
			ParserError();
		}
	}
	
	// Expr -> Term | Term + Expr | Term - Expr
	public static void Expr() {
		// if the nextToken has TokenCode ERROR
		if(token.code == Token.TokenCode.ERROR) {
			ParserError();
		}
		
		Term();
		
		if(token.code == Token.TokenCode.PLUS) {
			// do stuff with plus
			token = nextToken();
			Expr();
			System.out.println("PLUS" + " " + token.data);
		}
		if(token.code == Token.TokenCode.MINUS) {
			// System.out.println("before sub" + " " + token.data); ************
			token = nextToken();
			Expr();
			System.out.println("SUB" + " " + token.data);
		}
		
	}
	public static void Term() {
		// if the nextToken has TokenCode ERROR
		if(token.code == Token.TokenCode.ERROR) {
			ParserError();
		}
		
		// System.out.println("im inside before FActor...." + token.data);
		Factor();
		
		//token = nextToken();
		 //System.out.println("This inside Term  and my T is: " + token.data);
		
		if(token.code == Token.TokenCode.MULT){
			// System.out.println("before mult " + token.data);
			token = nextToken();
			// System.out.println("after mult " + token.data);
			Term();
			System.out.println("MULT");
		}
	}
	public static void Factor() {
		// if the nextToken has TokenCode ERROR
		if(token.code == Token.TokenCode.ERROR) {
			ParserError();
		}
		
		if(token.code == Token.TokenCode.INT) {
			//do stuff with INT
			//System.out.println("This inside Factor and my INT is: " + token.data);
			System.out.println("PUSH " + token.data);
			token = nextToken();
		}
		if(token.code == Token.TokenCode.ID) {
			//do stuff with ID
			//System.out.println("PUSH " + token.data); ********************************+
			System.out.println("PUSH " + token.data);
		}
		if(token.code == Token.TokenCode.LPAREN) {
			// switch to next token
			//System.out.println("This inside " + token.code + "  and my is: " + token.data);
			
			//System.out.println("This inside Lparen and my is: " + token.data);
			token = nextToken();
			Expr();
			if(token.code == Token.TokenCode.RPAREN) {
				//System.out.println("This is inside " + token.code + "  and my is: " + token.data);
				// token = nextToken();
			}
			else {
				//return error
				ParserError();
			}
		}
	}
	
	public static void main(String[] args){

		parse();
		
	}
}