Simple Translation Using Java

[Hunter McMillen]

Hey everyone,

I have an assignment for my computer organization class and I'm a little stuck. My professor wants us to create a java program that translates a made-up language: Tiny into a java program that runs correctly.

here is the spec for The Tiny Programming Language:

There is only one data type: integer.
A legal identifier may have one and only one lowercase letter in it (thus there are only 26 possible different identifiers).
A literal integer may have one and only one digit in it. Thus, the only literals are 0 to 9; no larger integers and no negative integers.
There are no declaration statements. All possible identifiers are implicitly delared to be integers and are initialized to 0.
All addition is done modulo 1000.
Statements must begin in column one and may contain no blank or tab characters.
There are three (and only three) kinds of statements in Tiny (in this description, the symbol A represents any legal identifier and the symbols X and Y represent any legal identifier or literal):

There are three statements types in Tiny.
A=X
Assigns the value of X to variable A. Remember, A can be any variable and X can be any variable OR single-digit number.

A=X+Y
Assigns the sum of X and Y to variable A. Remember, A can be any identifier. X and Y can be any identifier OR single-digit number. Thus, although the largest constant is 9, variables can take on values larger than 9.
(X)

Outputs the value of X followed by a newline character. Remember, X can be any variable OR single-digit number.

MY program works almost completely, the problem i have run into is that for my input data:

x=5
(3)
(x)
y=x+9
(z)
(y)
a=9+2
(a)

the variable z is never declared, in Tiny there are no declarations everything is declared implicitly and is initialized to 0. So instead of printing 0 my translated program gives me an error because I havent declared z.

Here is my code:

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

/* Tiny2Java Translator - translates a program written in the Tiny 
 * programming language to one written in the Java programming language
 *
 * @author Hunter McMillen
 * @date 1/22/10
 */
    public class Tiny2Java 
   {
   
       public static void main(String[] args) throws FileNotFoundException, IOException
      {
         File file = new File("mcmillhj-in.txt");
         Scanner kb = new Scanner(file);
         FileWriter writer = new FileWriter(new File("Tiny2.java"));
         String line = "";
      	
      	
         writer.write("public class Tiny" + "\n" + "{" + "\n" + "\tpublic static " +
             "void main(String[] args)" + "\n" + "{" + "\n");
         writer.flush();
      	
         
         while(kb.hasNextLine())
         {
            line = kb.nextLine();
            translate(line,writer);
         }
      	
         writer.write("\n" + "}" + "\n" + "}");
         writer.flush();
      }//end main
   
       public static void translate(String arg, FileWriter writer) throws IOException
      {  
         char temp; //holds the first character in a Tiny statement
         char holder; //holds a temporary string to be printed to the outfile
			holder = ' ';
         temp = arg.charAt(0);
      	
         if(temp >= 'a' && temp <= 'z')
         {
            writer.write("int " + temp + " " + arg.substring(1,arg.length())+ ";" + "\n");
            writer.flush();
         }
         else if(temp == '(')
         {
         	//this for loop reads the character inside the parens and stores
         	//them in a temporary string 
            for(int i = 1; i < arg.length(); i++)
            {
               if(arg.charAt(i) != ')')
               {
                  holder = arg.charAt(i);
               }
            }
            if(holder >= 'a' && holder <= 'z') //if holder is holding a reference to a variable
            {
               writer.write("System.out.println(" + holder + ");" + "\n");
            }
            else //if holder is holding a literal value
            {
               writer.write("System.out.println(" + "'" + holder + "'" + ");" + "\n");
            }
            writer.flush();
         }
      
      
      }//end translate
   }//end class

And here is the translated code i get with these inputs:

x=5
(3)
(x)
y=x+9
(z)
(y)
a=9+2
(a)

   
public class Tiny2
{
	public static void main(String[] args)
{
int x =5;
System.out.println('3');
System.out.println(x);
int y =x+9;
System.out.println(z);
System.out.println(y);
int a =9+2;
System.out.println(a);

}
}
 

Any help would be great.
Thanks,
Hunter

[fred rosenberger]

I'm guessing the problem comes on this line:

System.out.println(z);

in the Tiny2 class.

That's because java requires you to declare any variable you use. in your Tiny2 class, you never declared what 'z' was. Simply putting

int z = 0;

somewhere before your line 10 will solve that problem.

[Hunter McMillen]

Yes that is what I need to do to declare z, but I don't really want to hard code int z = 0; into the program its supposed to be able to translate the program no matter the inputs.

If i hard coded int z = 0; in then switched z to f then I would have to hard code for f as well, I'm looking for a more versatile solution.

-Hunter

[Henry Wong]

What happens when you do this?

x=1
y=2
x=x+y

Don't you have the another problem, in that the variable is now declared twice?

Henry

[Hunter McMillen]

Yes you are correct Henry that does cause another problem: I believe I have fixed both my problem and the one you brought up, its a bit clumsy but it works. Let me know what you think.

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

/* Tiny2Java Translator - translates a program written in the Tiny 
 * programming language to one written in the Java programming language
 *
 * @author Hunter McMillen
 * @date 1/22/10
 */
    public class Tiny2Java 
   {
   
       public static void main(String[] args) throws FileNotFoundException, IOException
      {
         File file = new File("mcmillhj-in.txt");
         Scanner kb = new Scanner(file);
         FileWriter writer = new FileWriter(new File("Tiny.java"));
         String line = "";
      	
         writer.write("public class Tiny" + "\n" + "{" + "\n" + "\tpublic static " +
             "void main(String[] args)" + "\n" + "{" + "\n");
         writer.flush();
      	
         findVariables(writer);
      	
         while(kb.hasNextLine())
         {
            line = kb.nextLine();
            translate(line,writer);
         }
      	
         writer.write("\n" + "}" + "\n" + "}");
         writer.flush();
      }//end main
   
   	/* findVariables searchs through the lines before the translate method
   	 * to ensure that all the variables that are to be printed (i.e. "(<some variable>)")
   	 * have been declared.
   	 *
   	 * @param FileWriter writer - object that writes information in the outfile
   	 */
       public static void findVariables(FileWriter writer) throws IOException
      {
         char temp = ' ';  //temporary holder of a character
         File file = new File("mcmillhj-in.txt");
         Scanner fS = new Scanner(file);
      	String line = "";
			
         while(fS.hasNextLine())
         {
            line = fS.nextLine();
            temp = line.charAt(0); //holds the first character in the incoming line
         
            if(temp == '(') //if the statement is holding a variable or literal to be printed
            {
            //since a Tiny statement can only print one literal value of variable value at a time
            //the value inside the parens will be at index 1
               temp = line.charAt(1);
            
               if(temp >= 'a' && temp <= 'z') //if holder is holding a reference to a variable
               {
               //declare the variable to ensure that all variables are declared
                  writer.write("int " + temp + " = 0;\n");
               }
            
            }
         }
      }//end findVariables
		
   	
   	 /* translate reads through the lines of the file as they are passed in
   	  * and determines what to write to the outfile based on the first character
   	  * in the current line.
   	  *
   	  * @param String arg - current line of the file to be translated
   	  * @param FileWriter writer - object that writes information in the outfile 
   	  */
       public static void translate(String arg, FileWriter writer) throws IOException
      {  
         char temp = ' '; //temporary holder of a character
         char holder = ' '; //holds a temporary string to be printed to the outfile
         temp = arg.charAt(0); //first character in the line being passed in
      
         if(temp == '(')
         {
            //since a Tiny statement can only print one literal value of variable value at a time
         	//the value inside the parens will be at index 1
            holder = arg.charAt(1);
            
            if(holder >= 'a' && holder <= 'z') //if holder is holding a reference to a variable
            {
            	//write the out statement to the file
               writer.write("System.out.println(" + holder + ");" + "\n");
            }
            else //if holder is holding a literal value
            {
               writer.write("System.out.println(" + "'" + holder + "'" + ");" + "\n");
            }//end if
            writer.flush();
         
         }
         else if(temp >= 'a' && temp <= 'z')
         {
            writer.write(temp + " " + arg.substring(1,arg.length())+ ";" + "\n");
            writer.flush();
         }//end if
      
      
      }//end translate
   }//end class

-Hunter