Source code: javax/ide/extension/spi/ScopedMap.java

   package javax.ide.extension.spi;
   
   import java.util.AbstractMap;
   import java.util.HashMap;
   import java.util.HashSet;
   import java.util.Iterator;
   import java.util.Map;
   import java.util.Set;
   
  /**
   * A map that provides support for scoping.
   */
  public final class ScopedMap extends AbstractMap
  {
    private final Stack _mapStack = new Stack();
    
    public ScopedMap()
    {
      enterScope();    // Always have a root scope to avoid illegal object states  
    }
    
    /**
     * Enter a new scope level.  
     */
    public void enterScope()
    {
      _mapStack.push( new HashMap() );
    }
    
    /**
     * Exit the current scope level. Name / value pairs that
     * were defined in the current scope will no longer be available.
     */
    public void exitScope()
    {
      _mapStack.pop();
    }
    
    
    public Object put( Object key, Object value )
    {
      Map topMap = (Map) _mapStack.peek();
      return topMap.put( key, value );
    }
    
    public Object get( Object key )
    {
      for ( Iterator i = _mapStack.iterator(); i.hasNext(); )
      {
        Map thisMap = (Map) i.next();
        Object o = thisMap.get( key );
        if ( o != null )
        {
          return o;
        }
      }
      return null;
    }
    
    public Object remove( Object key )
    {
      for ( Iterator i = _mapStack.iterator(); i.hasNext(); )
      {
        Map thisMap = (Map) i.next(); 
        Object o = thisMap.remove( key );
        if ( o != null )
        {
          return o;
        }
      }
      return null;
    }
    
    public void clear()
    {
      for ( Iterator i = _mapStack.iterator(); i.hasNext(); )
      {
        ((Map)i.next()).clear();
      }
    }
    
    public Set entrySet()
    {
      HashSet hs = new HashSet();
      for ( Iterator i = _mapStack.iterator(); i.hasNext(); )
      {
        Map thisMap = (Map) i.next();
        hs.addAll( thisMap.entrySet() );
      }
      return hs;
    }
  }