/** CS 363 Lab 5
 *  Let's take a look at block variable (register) allocation.
 *  We will scan some variable "declarations" that occur in
 *  blocks, and see how many distinct memory locations are needed.
 *  Note that variables declared in mutually exclusive blocks
 *  can be overlapped in memory.
 *  Example input:      The variables can be stored as:
 *  {                   R1:  a
 *    declare a;        R2:  b	
 *    declare b;        R3:  c
 *    declare c;        R4:  x, r [they can share same space!]
 *    {                 R5:  y
 *      declare x;
 *      declare y;
 *    }
 *    {
 *      declare r;
 *    }
 *  }
 */
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.Scanner;
import java.util.StringTokenizer;
import java.util.Stack;
import java.util.ArrayList;

public class Driver
{
  public static void main(String [] args) throws FileNotFoundException
  {
    // A register is a list of variables.
    ArrayList [] register = new ArrayList [32];

    Scanner kbd = new Scanner(System.in);   
    System.out.print("What is the name of the input file?  ");
    String fileName = kbd.nextLine();
    Scanner in = new Scanner(new FileInputStream(fileName));
    Stack<Variable> stack = new Stack<Variable>();
    int regNum = 1;
    int nestLevel = 0;
    
    // At this point we have the file, being read by the stream "in".
    while (in.hasNextLine())
    {
      String line = in.nextLine();

      // What should I do with the input line?  If blank, skip it.  :)
      // Each line of the input file could be:
      // Case 1:  an open curly brace "{"
      // Case 2:  a close curly brace "}"
      // Case 3:  a declaration.

      StringTokenizer tok = new StringTokenizer(line, " ;");
      if (tok.countTokens() == 0)
        continue;

      String token = tok.nextToken();
      if (token.equals("{"))
      {
         // ADD CODE HERE
      }
      else if (token.equals("}"))
      {
         // ADD CODE HERE
      }
      else // it's a variable declaration!
      {
        String varName = tok.nextToken();
        Variable v = new Variable(varName, nestLevel);
        
        // ADD CODE HERE
      }
    }
    
    // Output the variables assigned to each register.
    for (int i = 1; i <= 31; ++i)
    {
      if (register[i] == null)
        continue;
      int numVariables = register[i].size();

      System.out.printf("Register %2d:  ", i);
      for (int j = 0; j < numVariables - 1; ++j)
        System.out.printf("%s, ", register[i].get(j).toString());
      System.out.printf("%s\n", register[i].get(numVariables - 1).toString());
    }
  }
}