1   /*
    2    * Copyright (c) 2003, Oracle and/or its affiliates. All rights reserved.
    3    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
    4    *
    5    * This code is free software; you can redistribute it and/or modify it
    6    * under the terms of the GNU General Public License version 2 only, as
    7    * published by the Free Software Foundation.  Oracle designates this
    8    * particular file as subject to the "Classpath" exception as provided
    9    * by Oracle in the LICENSE file that accompanied this code.
   10    *
   11    * This code is distributed in the hope that it will be useful, but WITHOUT
   12    * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   13    * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   14    * version 2 for more details (a copy is included in the LICENSE file that
   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   /**
   34    * Abstract superclass for lazy scope objects, used when building
   35    * factories for generic information repositories.
   36    * The type parameter <tt>D</tt> represents the type of reflective
   37    * object whose scope this class is representing.
   38    * <p> To subclass this, all one needs to do is implement
   39    * <tt>computeEnclosingScope</tt> and the subclass' constructor.
   40    */
   41   public abstract class AbstractScope<D extends GenericDeclaration>
   42       implements Scope {
   43   
   44       private D recvr; // the declaration whose scope this instance represents
   45       private Scope enclosingScope; // the enclosing scope of this scope
   46   
   47       /**
   48        * Constructor. Takes a reflective object whose scope the newly
   49        * constructed instance will represent.
   50        * @param D - A generic declaration whose scope the newly
   51        * constructed instance will represent
   52        */
   53       protected AbstractScope(D decl){ recvr = decl;}
   54   
   55       /**
   56        * Accessor for the receiver - the object whose scope this <tt>Scope</tt>
   57        * object represents.
   58        * @return The object whose scope this <tt>Scope</tt> object represents
   59        */
   60       protected D getRecvr() {return recvr;}
   61   
   62       /** This method must be implemented by any concrete subclass.
   63        * It must return the enclosing scope of this scope. If this scope
   64        * is a top-level scope, an instance of  DummyScope must be returned.
   65        * @return The enclosing scope of this scope
   66        */
   67       protected abstract Scope computeEnclosingScope();
   68   
   69       /**
   70        * Accessor for the enclosing scope, which is computed lazily and cached.
   71        * @return the enclosing scope
   72        */
   73       protected Scope getEnclosingScope(){
   74           if (enclosingScope == null) {enclosingScope = computeEnclosingScope();}
   75           return enclosingScope;
   76       }
   77   
   78       /**
   79        * Lookup a type variable in the scope, using its name. Returns null if
   80        * no type variable with this name is declared in this scope or any of its
   81        * surrounding scopes.
   82        * @param name - the name of the type variable being looked up
   83        * @return the requested type variable, if found
   84        */
   85       public TypeVariable<?> lookup(String name) {
   86           TypeVariable[] tas = getRecvr().getTypeParameters();
   87           for (TypeVariable/*<?>*/ tv : tas) {
   88               if (tv.getName().equals(name)) {return tv;}
   89           }
   90           return getEnclosingScope().lookup(name);
   91       }
   92   }