package LBJ2.infer;


/**
  * Anonymous inner classes extending this class are instantiated by the code
  * generated by the LBJ compiler when creating
  * <code>FirstOrderConstraint</code> representations.  The methods of this
  * class are used to compute new values for the arguments of a quantified
  * <code>FirstOrderEquality</code>.  Only certain value returning methods are
  * overridden.  The others will throw
  * <code>UnsupportedOperationException</code>s.
  *
  * @see    LBJ2.infer.FirstOrderConstraint
  * @see    LBJ2.infer.FirstOrderEquality
  * @see    java.lang.UnsupportedOperationException
  * @author Nick Rizzolo
 **/
abstract public class EqualityArgumentReplacer extends ArgumentReplacer
{
  /**
    * This flag is set if the left hand side of the equality is not
    * quantified.
   **/
  public boolean leftConstant;
  /**
    * This flag is set if the right hand side of the equality is not
    * quantified.
   **/
  public boolean rightConstant;


  /**
    * Initializing constructor.
    *
    * @param c  The context of the corresponding equality, except for
    *           quantification variables.
   **/
  public EqualityArgumentReplacer(Object[] c) {
    super(c);
    leftConstant = rightConstant = false;
  }

  /**
    * Use this constructor to indicate which of the two arguments of the
    * equality is in fact not quantified.
    *
    * @param c  The context of the corresponding equality, except for
    *           quantification variables.
    * @param r  Set to <code>false</code> if the unquantified argument is the
    *           left; set to <code>true</code> if the unquantified argument is
    *           the right.
   **/
  public EqualityArgumentReplacer(Object[] c, boolean r) {
    super(c);
    leftConstant = !r;
    rightConstant = r;
  }


  /**
    * Computes the value on the left hand side of the equality.  This method
    * needs to be overridden if it is to be called, since by default it simply
    * throws an <code>UnsupportedOperationException</code>.
   **/
  public String getLeftValue() {
    throw new UnsupportedOperationException(
        "LBJ ERROR: getLeftValue() not supported.");
  }


  /**
    * Computes the value on the right hand side of the equality.  This method
    * needs to be overridden if it is to be called, since by default it simply
    * throws an <code>UnsupportedOperationException</code>.
   **/
  public String getRightValue() {
    throw new UnsupportedOperationException(
        "LBJ ERROR: getRightValue() not supported.");
  }


  /**
    * Computes the object on the left hand side of the equality.  This method
    * needs to be overridden if it is to be called, since by default it simply
    * throws an <code>UnsupportedOperationException</code>.
   **/
  public Object getLeftObject() {
    throw new UnsupportedOperationException(
        "LBJ ERROR: getLeftObject() not supported.");
  }


  /**
    * Computes the object on the right hand side of the equality.  This method
    * needs to be overridden if it is to be called, since by default it simply
    * throws an <code>UnsupportedOperationException</code>.
   **/
  public Object getRightObject() {
    throw new UnsupportedOperationException(
        "LBJ ERROR: getRightObject() not supported.");
  }
}