/** Our internal representation of a ParenExpr
 * in the Q0 language.
 * See http://www.radford.edu/itec380/2009fall-ibarland/Hw06/hw06.html
 * 
 * @author Ian Barland
 * @version 2015.Nov.15
 */
public class ParenExpr extends Expr {

  Expr e;

  ParenExpr( Expr _e ) {
    this.e  = _e;
    }
  
  public String toString(/* ParenExpr this */) {
    return "[["
         + this.e.toString()
         + "]]"
         ;
    }
    
  public Value eval() {
    return this.e.eval();
    }
  
  public Expr subst( /* ParityExpr this, */ IdExpr id, Value v ) {
    return  new ParenExpr( this.e.subst(id,v) );
    }

    
  @Override
  public boolean equals( /* ParenExpr this, */ Object that) {
    if (this==that) {
      return true;
      }
   else if (that==null) {
      return false;
      }
   else if (this.getClass() != that.getClass()) {
      return false;
      }
   else {
      ParenExpr thatt = (ParenExpr) that;
      return this.e.equals(thatt.e);
      }
    
    }
    
  @Override
  public int hashCode() {
    if (cachedHash == null) {
      int hashSoFar = 0x815F58D4; // fingerprint
      hashSoFar += this.e.hashCode();
      cachedHash = hashSoFar;
      }
    return cachedHash;
    }
  private Integer cachedHash = null;
 
  }