1   /*
    2    * Copyright (c) 2005, 2008, 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 com.sun.tools.javac.model;
   27   
   28   import java.util.AbstractList;
   29   import java.util.Iterator;
   30   import java.util.NoSuchElementException;
   31   import com.sun.tools.javac.code.Scope;
   32   import com.sun.tools.javac.code.Symbol;
   33   
   34   import static com.sun.tools.javac.code.Flags.*;
   35   
   36   /**
   37    * Utility to construct a view of a symbol's members,
   38    * filtering out unwanted elements such as synthetic ones.
   39    * This view is most efficiently accessed through its iterator() method.
   40    *
   41    * <p><b>This is NOT part of any supported API.
   42    * If you write code that depends on this, you do so at your own risk.
   43    * This code and its internal interfaces are subject to change or
   44    * deletion without notice.</b>
   45    */
   46   public class FilteredMemberList extends AbstractList<Symbol> {
   47   
   48       private final Scope scope;
   49   
   50       public FilteredMemberList(Scope scope) {
   51           this.scope = scope;
   52       }
   53   
   54       public int size() {
   55           int cnt = 0;
   56           for (Scope.Entry e = scope.elems; e != null; e = e.sibling) {
   57               if (!unwanted(e.sym))
   58                   cnt++;
   59           }
   60           return cnt;
   61       }
   62   
   63       public Symbol get(int index) {
   64           for (Scope.Entry e = scope.elems; e != null; e = e.sibling) {
   65               if (!unwanted(e.sym) && (index-- == 0))
   66                   return e.sym;
   67           }
   68           throw new IndexOutOfBoundsException();
   69       }
   70   
   71       // A more efficient implementation than AbstractList's.
   72       public Iterator<Symbol> iterator() {
   73           return new Iterator<Symbol>() {
   74   
   75               /** The next entry to examine, or null if none. */
   76               private Scope.Entry nextEntry = scope.elems;
   77   
   78               private boolean hasNextForSure = false;
   79   
   80               public boolean hasNext() {
   81                   if (hasNextForSure) {
   82                       return true;
   83                   }
   84                   while (nextEntry != null && unwanted(nextEntry.sym)) {
   85                       nextEntry = nextEntry.sibling;
   86                   }
   87                   hasNextForSure = (nextEntry != null);
   88                   return hasNextForSure;
   89               }
   90   
   91               public Symbol next() {
   92                   if (hasNext()) {
   93                       Symbol result = nextEntry.sym;
   94                       nextEntry = nextEntry.sibling;
   95                       hasNextForSure = false;
   96                       return result;
   97                   } else {
   98                       throw new NoSuchElementException();
   99                   }
  100               }
  101   
  102               public void remove() {
  103                   throw new UnsupportedOperationException();
  104               }
  105           };
  106       }
  107   
  108       /**
  109        * Tests whether this is a symbol that should never be seen by
  110        * clients, such as a synthetic class.  Returns true for null.
  111        */
  112       private static boolean unwanted(Symbol s) {
  113           return s == null  ||  (s.flags() & SYNTHETIC) != 0;
  114       }
  115   }