/**
  * Copyright (c): Uwe Schmidt, FH Wedel
  *
  * You may study, modify and distribute this source code
  * FOR NON-COMMERCIAL PURPOSES ONLY.
  * This copyright message has to remain unchanged.
  *
  * Note that this document is provided 'as is',
  * WITHOUT WARRANTY of any kind either expressed or implied.
  */

public
class UnaryMinus extends UnaryExpr {

  //--------------------

  public
  UnaryMinus(Expr operand) {
    super(operand);
  }

  //--------------------

  // op1 negiert den Wert
  // Operation erlaubt fuer int und double Werte

  protected
  Object op1(Object v1) {

    // - fuer int

    if ( v1 instanceof Integer ) {
      return
	new Integer(- ((Integer)v1).intValue());
    }

    // - fuer double

    if ( v1 instanceof Double ) {
      return
	new Double(- ((Double)v1).doubleValue());
    }

    // nicht erlaubtes Argument

    throw
      new IllegalArgumentException("unary - : illegal operand type");
  }

  //--------------------

  public
  String op1ToString() {
    return
      "-";
  }
}

//--------------------