third_party/WebKit/Source/wtf/RawPtr.h

   1 /*
   2  * Copyright (C) 2014 Google Inc. 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 #ifndef WTF_RawPtr_h
  32 #define WTF_RawPtr_h
  33
  34 #include "wtf/HashTableDeletedValueType.h"
  35 #include "wtf/TypeTraits.h"
  36 #include <algorithm>
  37 #include <stdint.h>
  38 #include <utility>
  39
  40 // RawPtr is a simple wrapper for a raw pointer that provides the
  41 // interface (get, clear) of other pointer types such as RefPtr,
  42 // Persistent and Member. This is used for the Blink garbage
  43 // collection work in order to be able to write shared code that will
  44 // use reference counting or garbage collection based on a
  45 // compile-time flag.
  46
  47 namespace WTF {
  48
  49 template<typename T>
  50 class RawPtr {
  51 public:
  52     RawPtr()
  53     {
  54 #if ENABLE(ASSERT)
  55         m_ptr = reinterpret_cast<T*>(rawPtrZapValue);
  56 #endif
  57     }
  58     RawPtr(std::nullptr_t) : m_ptr(0) { }
  59     RawPtr(T* ptr) : m_ptr(ptr) { }
  60     explicit RawPtr(T& reference) : m_ptr(&reference) { }
  61     RawPtr(const RawPtr& other)
  62         : m_ptr(other.get())
  63     {
  64     }
  65
  66     template<typename U>
  67     RawPtr(const RawPtr<U>& other, EnsurePtrConvertibleArgDecl(U, T))
  68         : m_ptr(other.get())
  69     {
  70     }
  71
  72     // Hash table deleted values, which are only constructed and never copied or destroyed.
  73     RawPtr(HashTableDeletedValueType) : m_ptr(hashTableDeletedValue()) { }
  74     bool isHashTableDeletedValue() const { return m_ptr == hashTableDeletedValue(); }
  75
  76     T* get() const { return m_ptr; }
  77     void clear() { m_ptr = 0; }
  78     RawPtr<T> release()
  79     {
  80         RawPtr<T> tmp = m_ptr;
  81         m_ptr = 0;
  82         return tmp;
  83     }
  84     T* leakRef()
  85     {
  86         T* ptr = m_ptr;
  87         m_ptr = 0;
  88         return ptr;
  89     }
  90     T* leakPtr()
  91     {
  92         T* ptr = m_ptr;
  93         m_ptr = 0;
  94         return ptr;
  95     }
  96
  97     template<typename U>
  98     RawPtr& operator=(U* ptr)
  99     {
 100         m_ptr = ptr;
 101         return *this;
 102     }
 103
 104     template<typename U>
 105     RawPtr& operator=(RawPtr<U> ptr)
 106     {
 107         m_ptr = ptr.get();
 108         return *this;
 109     }
 110
 111     RawPtr& operator=(std::nullptr_t)
 112     {
 113         m_ptr = 0;
 114         return *this;
 115     }
 116
 117     operator T*() const { return m_ptr; }
 118     T& operator*() const { return *m_ptr; }
 119     T* operator->() const { return m_ptr; }
 120     bool operator!() const { return !m_ptr; }
 121
 122     void swap(RawPtr& o)
 123     {
 124         std::swap(m_ptr, o.m_ptr);
 125     }
 126
 127     static T* hashTableDeletedValue() { return reinterpret_cast<T*>(-1); }
 128
 129 private:
 130     static const uintptr_t rawPtrZapValue = 0x3a3a3a3a;
 131     T* m_ptr;
 132 };
 133
 134 template<typename T, typename U> inline RawPtr<T> static_pointer_cast(const RawPtr<U>& p)
 135 {
 136     return RawPtr<T>(static_cast<T*>(p.get()));
 137 }
 138
 139 template<typename T> inline T* getPtr(const RawPtr<T>& p)
 140 {
 141     return p.get();
 142 }
 143
 144 } // namespace WTF
 145
 146 using WTF::RawPtr;
 147
 148 #endif