// Copyright (c) 2004  Per M.A. Bothner.
// This is free software;  for terms and warranty disclaimer see ./COPYING.

package gnu.mapping;

public class PlainLocation extends NamedLocation
{
  public PlainLocation (Symbol symbol, Object property)
  {
    super(symbol, property);
  }

  public PlainLocation (Symbol symbol, Object property, Object value)
  {
    super(symbol, property);
    this.value = value;
  }

  public final Object get (Object defaultValue)
  {
    return base != null ? base.get(defaultValue)
      : value == Location.UNBOUND ? defaultValue : value;
  }

  public boolean isBound ()
  {
    return base != null ? base.isBound() : value != Location.UNBOUND;
  }

  public final void set (Object newValue)
  {
    if (base == null)
      value = newValue;
    else if (value == DIRECT_ON_SET)
      {
	base = null;
	value = newValue;
      }
    else if (base.isConstant())
      getEnvironment().put(getKeySymbol(), getKeyProperty(), newValue);
    else
      base.set(newValue);
  }

  public Object setWithSave (Object newValue)
  {
    Object old;
    if (base != null)
      {
	if (value == INDIRECT_FLUIDS)
	  return base.setWithSave(newValue);
	old = base;
	base = null;
      }
    else
      {
	old = value;
      }
    value = newValue;
    return old;
  }

  public void setRestore (Object oldValue)
  {
    if (base != null)
      base.setRestore(oldValue);
    else if (oldValue instanceof Location)
      {
	value = null;
	base = (Location) oldValue;
      }
    else
      value = oldValue;
  }
}
