1 /*
   2  * Copyright (c) 2020, 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.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_UTILITIES_VALUEOBJARRAY_HPP
  26 #define SHARE_UTILITIES_VALUEOBJARRAY_HPP
  27 
  28 #include "utilities/debug.hpp"
  29 
  30 // Stamps out Count instances of Type using a recursive template.
  31 template <typename Type, int Count>
  32 class ValueObjBlock {
  33   typedef ValueObjBlock<Type, Count - 1> Next;
  34 
  35   Type _instance;
  36   Next _next;
  37 
  38 public:
  39   template <typename Generator>
  40   ValueObjBlock(Generator g, Type** save_to) :
  41       _instance(*g),
  42       _next(++g, save_to + 1) {
  43     *save_to = &_instance;
  44   }
  45 };
  46 
  47 // Specialization for the recursion base case.
  48 template <typename Type>
  49 class ValueObjBlock<Type, 0> {
  50 public:
  51   template <typename Generator>
  52   ValueObjBlock(Generator, Type**) {}
  53 };
  54 
  55 // Maps an array of size Count over stamped-out instances of Type.
  56 template <typename Type, int Count>
  57 struct ValueObjArray {
  58   Type*                      _ptrs[Count];
  59   ValueObjBlock<Type, Count> _block;
  60 
  61   template <typename Generator>
  62   ValueObjArray(Generator g) : _ptrs(), _block(g, _ptrs) {}
  63 
  64   Type* at(int index) const {
  65     assert(0 <= index && index < Count, "index out-of-bounds: %d", index);
  66     return _ptrs[index];
  67   }
  68 
  69   static int count() {
  70     return Count;
  71   }
  72 };
  73 
  74 #endif // SHARE_UTILITIES_VALUEOBJARRAY_HPP