1/* Copyright (c) 2006, Google Inc.
2 * All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are
6 * met:
7 *
8 *     * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 *     * Redistributions in binary form must reproduce the above
11 * copyright notice, this list of conditions and the following disclaimer
12 * in the documentation and/or other materials provided with the
13 * distribution.
14 *     * Neither the name of Google Inc. nor the names of its
15 * contributors may be used to endorse or promote products derived from
16 * this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 *
30 * ---
31 * Author: Maxim Lifantsev
32 */
33
34
35#ifndef BASE_STL_ALLOCATOR_H_
36#define BASE_STL_ALLOCATOR_H_
37
38#include <config.h>
39
40#include <stddef.h>   // for ptrdiff_t
41#include <limits>
42
43#include "base/logging.h"
44
45// Generic allocator class for STL objects
46// that uses a given type-less allocator Alloc, which must provide:
47//   static void* Alloc::Allocate(size_t size);
48//   static void Alloc::Free(void* ptr, size_t size);
49//
50// STL_Allocator<T, MyAlloc> provides the same thread-safety
51// guarantees as MyAlloc.
52//
53// Usage example:
54//   set<T, less<T>, STL_Allocator<T, MyAlloc> > my_set;
55// CAVEAT: Parts of the code below are probably specific
56//         to the STL version(s) we are using.
57//         The code is simply lifted from what std::allocator<> provides.
58template <typename T, class Alloc>
59class STL_Allocator {
60 public:
61  typedef size_t     size_type;
62  typedef ptrdiff_t  difference_type;
63  typedef T*         pointer;
64  typedef const T*   const_pointer;
65  typedef T&         reference;
66  typedef const T&   const_reference;
67  typedef T          value_type;
68
69  template <class T1> struct rebind {
70    typedef STL_Allocator<T1, Alloc> other;
71  };
72
73  STL_Allocator() { }
74  STL_Allocator(const STL_Allocator&) { }
75  template <class T1> STL_Allocator(const STL_Allocator<T1, Alloc>&) { }
76  ~STL_Allocator() { }
77
78  pointer address(reference x) const { return &x; }
79  const_pointer address(const_reference x) const { return &x; }
80
81  pointer allocate(size_type n, const void* = 0) {
82    RAW_DCHECK((n * sizeof(T)) / sizeof(T) == n, "n is too big to allocate");
83    return static_cast<T*>(Alloc::Allocate(n * sizeof(T)));
84  }
85  void deallocate(pointer p, size_type n) { Alloc::Free(p, n * sizeof(T)); }
86
87  size_type max_size() const { return size_t(-1) / sizeof(T); }
88
89  void construct(pointer p, const T& val) { ::new(p) T(val); }
90  void construct(pointer p) { ::new(p) T(); }
91  void destroy(pointer p) { p->~T(); }
92
93  // There's no state, so these allocators are always equal
94  bool operator==(const STL_Allocator&) const { return true; }
95};
96
97#endif  // BASE_STL_ALLOCATOR_H_
98