third_party/tcmalloc/chromium/src/base/stl_allocator.h

   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:
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   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.
  58 template <typename T, class Alloc>
  59 class 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_