15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package sun.reflect.generics.scope;
  27 
  28 import java.lang.reflect.GenericDeclaration;
  29 import java.lang.reflect.TypeVariable;
  30 
  31 
  32 /**
  33  * Abstract superclass for lazy scope objects, used when building
  34  * factories for generic information repositories.
  35  * The type parameter <tt>D</tt> represents the type of reflective
  36  * object whose scope this class is representing.
  37  * <p> To subclass this, all one needs to do is implement
  38  * <tt>computeEnclosingScope</tt> and the subclass' constructor.
  39  */
  40 public abstract class AbstractScope<D extends GenericDeclaration>
  41     implements Scope {
  42 
  43     private final D recvr; // the declaration whose scope this instance represents
  44 
  45     /** The enclosing scope of this scope.  Lazily initialized. */
  46     private volatile Scope enclosingScope;
  47 
  48     /**
  49      * Constructor. Takes a reflective object whose scope the newly
  50      * constructed instance will represent.
  51      * @param decl - A generic declaration whose scope the newly
  52      * constructed instance will represent
  53      */
  54     protected AbstractScope(D decl){ recvr = decl;}
  55 
  56     /**
  57      * Accessor for the receiver - the object whose scope this <tt>Scope</tt>
  58      * object represents.
  59      * @return The object whose scope this <tt>Scope</tt> object represents
  60      */
  61     protected D getRecvr() {return recvr;}
  62 
  63     /** This method must be implemented by any concrete subclass.
  64      * It must return the enclosing scope of this scope. If this scope
  65      * is a top-level scope, an instance of DummyScope must be returned.
  66      * @return The enclosing scope of this scope
  67      */
  68     protected abstract Scope computeEnclosingScope();
  69 
  70     /**
  71      * Accessor for the enclosing scope, which is computed lazily and cached.
  72      * @return the enclosing scope
  73      */
  74     protected Scope getEnclosingScope() {
  75         Scope value = enclosingScope;
  76         if (value == null) {
  77             value = computeEnclosingScope();
  78             enclosingScope = value;
  79         }

  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package sun.reflect.generics.scope;
  27 
  28 import java.lang.reflect.GenericDeclaration;
  29 import java.lang.reflect.TypeVariable;
  30 
  31 
  32 /**
  33  * Abstract superclass for lazy scope objects, used when building
  34  * factories for generic information repositories.
  35  * The type parameter {@code D} represents the type of reflective
  36  * object whose scope this class is representing.
  37  * <p> To subclass this, all one needs to do is implement
  38  * {@code computeEnclosingScope} and the subclass' constructor.
  39  */
  40 public abstract class AbstractScope<D extends GenericDeclaration>
  41     implements Scope {
  42 
  43     private final D recvr; // the declaration whose scope this instance represents
  44 
  45     /** The enclosing scope of this scope.  Lazily initialized. */
  46     private volatile Scope enclosingScope;
  47 
  48     /**
  49      * Constructor. Takes a reflective object whose scope the newly
  50      * constructed instance will represent.
  51      * @param decl - A generic declaration whose scope the newly
  52      * constructed instance will represent
  53      */
  54     protected AbstractScope(D decl){ recvr = decl;}
  55 
  56     /**
  57      * Accessor for the receiver - the object whose scope this {@code Scope}
  58      * object represents.
  59      * @return The object whose scope this {@code Scope} object represents
  60      */
  61     protected D getRecvr() {return recvr;}
  62 
  63     /** This method must be implemented by any concrete subclass.
  64      * It must return the enclosing scope of this scope. If this scope
  65      * is a top-level scope, an instance of DummyScope must be returned.
  66      * @return The enclosing scope of this scope
  67      */
  68     protected abstract Scope computeEnclosingScope();
  69 
  70     /**
  71      * Accessor for the enclosing scope, which is computed lazily and cached.
  72      * @return the enclosing scope
  73      */
  74     protected Scope getEnclosingScope() {
  75         Scope value = enclosingScope;
  76         if (value == null) {
  77             value = computeEnclosingScope();
  78             enclosingScope = value;
  79         }