1 /*
   2  * Copyright (c) 2003, 2004, 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.repository;
  27 
  28 import java.lang.reflect.TypeVariable;
  29 import sun.reflect.generics.factory.GenericsFactory;
  30 import sun.reflect.generics.tree.FormalTypeParameter;
  31 import sun.reflect.generics.tree.Signature;
  32 import sun.reflect.generics.visitor.Reifier;
  33 
  34 
  35 
  36 /**
  37  * This class represents the generic type information for a generic
  38  * declaration.
  39  * The code is not dependent on a particular reflective implementation.
  40  * It is designed to be used unchanged by at least core reflection and JDI.
  41  */
  42 public abstract class GenericDeclRepository<S extends Signature>
  43     extends AbstractRepository<S> {
  44 
  45     private volatile TypeVariable[] typeParams; // caches the formal type parameters
  46 
  47     protected GenericDeclRepository(String rawSig, GenericsFactory f) {
  48         super(rawSig, f);
  49     }
  50 
  51     // public API
  52  /*
  53  * When queried for a particular piece of type information, the
  54  * general pattern is to consult the corresponding cached value.
  55  * If the corresponding field is non-null, it is returned.
  56  * If not, it is created lazily. This is done by selecting the appropriate
  57  * part of the tree and transforming it into a reflective object
  58  * using a visitor.
  59  * a visitor, which is created by feeding it the factory
  60  * with which the repository was created.
  61  */
  62 
  63     /**
  64      * Return the formal type parameters of this generic declaration.
  65      * @return the formal type parameters of this generic declaration
  66      */
  67     public TypeVariable/*<?>*/[] getTypeParameters(){
  68         TypeVariable[] typeParams = this.typeParams;
  69         if (typeParams == null) { // lazily initialize type parameters
  70             // first, extract type parameter subtree(s) from AST
  71             FormalTypeParameter[] ftps = getTree().getFormalTypeParameters();
  72             // create array to store reified subtree(s)
  73             TypeVariable[] tps = new TypeVariable[ftps.length];
  74             // reify all subtrees
  75             for (int i = 0; i < ftps.length; i++) {
  76                 Reifier r = getReifier(); // obtain visitor
  77                 ftps[i].accept(r); // reify subtree
  78                 // extract result from visitor and store it
  79                 tps[i] = (TypeVariable<?>) r.getResult();
  80             }
  81             typeParams = tps; // cache overall result
  82             this.typeParams = typeParams;
  83         }
  84         return typeParams.clone(); // return cached result
  85     }
  86 }