package rebelsky.pal;

/**
 * The PAL instruction to write a constant string.
 *
 * @author Samuel A. Rebelsky
 * @version 1.0 of November 2002.
 */
public class SWrite
  implements Instruction
{
  // +--------+------------------------------------------------------------
  // | Fields |
  // +--------+

  /** The string to write. */
  String str;


  // +--------------+------------------------------------------------------
  // | Constructors |
  // +--------------+

  /** 
   * Create a new instruction to write a string.
   */
  public SWrite(String str)
  {
    this.str = str;
  } // SWrite(String)


  // +---------+-----------------------------------------------------------
  // | Methods |
  // +---------+

  /** 
   * Execute the instruction on a machine. 
   * 
   * @exception Exception
   *   If the memory location is invalid.
   */
  public void execute(Computer hal)
    throws Exception
  {
    hal.out.print(str);
    hal.out.flush();
  } // execute(Computer)

  /** Convert the instruction to a string (usually for printing). */
  public String toString()
  {
    return "  SWRITE '" + str + "'";
  } // toString()

} // class SWrite