DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Mercurial (b9a9e0b6f0df)

VCS Links

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: set ts=8 sts=2 et sw=2 tw=80:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef vm_SharedMem_h
#define vm_SharedMem_h

#include "mozilla/TypeTraits.h"

template <typename T>
class SharedMem {
  // static_assert(mozilla::IsPointer<T>::value,
  //               "SharedMem encapsulates pointer types");

  enum Sharedness { IsUnshared, IsShared };

  T ptr_;
#ifdef DEBUG
  Sharedness sharedness_;
#endif

  SharedMem(T ptr, Sharedness sharedness)
      : ptr_(ptr)
#ifdef DEBUG
        ,
        sharedness_(sharedness)
#endif
  {
  }

 public:
  // Create a SharedMem<T> that is an unshared nullptr.
  SharedMem()
      : ptr_(nullptr)
#ifdef DEBUG
        ,
        sharedness_(IsUnshared)
#endif
  {
  }

  // Create a SharedMem<T> that's shared/unshared in the same way as
  // "forSharedness".
  SharedMem(T ptr, const SharedMem& forSharedness)
      : ptr_(ptr)
#ifdef DEBUG
        ,
        sharedness_(forSharedness.sharedness_)
#endif
  {
  }

  // Create a SharedMem<T> that's marked as shared.
  static SharedMem shared(void* p) {
    return SharedMem(static_cast<T>(p), IsShared);
  }

  // Create a SharedMem<T> that's marked as unshared.
  static SharedMem unshared(void* p) {
    return SharedMem(static_cast<T>(p), IsUnshared);
  }

  SharedMem& operator=(const SharedMem& that) {
    ptr_ = that.ptr_;
#ifdef DEBUG
    sharedness_ = that.sharedness_;
#endif
    return *this;
  }

  // Reinterpret-cast the pointer to type U, preserving sharedness.
  // Eg, "obj->dataPointerEither().cast<uint8_t*>()" yields a
  // SharedMem<uint8_t*>.
  template <typename U>
  inline SharedMem<U> cast() const {
#ifdef DEBUG
    MOZ_ASSERT(asValue() %
                   sizeof(mozilla::Conditional<
                          mozilla::IsVoid<
                              typename mozilla::RemovePointer<U>::Type>::value,
                          char, typename mozilla::RemovePointer<U>::Type>) ==
               0);
    if (sharedness_ == IsUnshared) {
      return SharedMem<U>::unshared(unwrap());
    }
#endif
    return SharedMem<U>::shared(unwrap());
  }

  explicit operator bool() { return ptr_ != nullptr; }

  SharedMem operator+(size_t offset) { return SharedMem(ptr_ + offset, *this); }

  SharedMem operator-(size_t offset) { return SharedMem(ptr_ - offset, *this); }

  SharedMem operator++() {
    ptr_++;
    return *this;
  }

  SharedMem operator++(int) {
    SharedMem<T> result(*this);
    ptr_++;
    return result;
  }

  SharedMem operator--() {
    ptr_--;
    return *this;
  }

  SharedMem operator--(int) {
    SharedMem<T> result(*this);
    ptr_--;
    return result;
  }

  uintptr_t asValue() const { return reinterpret_cast<uintptr_t>(ptr_); }

  // Cast to char*, add nbytes, and cast back to T.  Simplifies code in a few
  // places.
  SharedMem addBytes(size_t nbytes) {
    MOZ_ASSERT(nbytes %
                   sizeof(mozilla::Conditional<
                          mozilla::IsVoid<
                              typename mozilla::RemovePointer<T>::Type>::value,
                          char, typename mozilla::RemovePointer<T>::Type>) ==
               0);
    return SharedMem(
        reinterpret_cast<T>(reinterpret_cast<char*>(ptr_) + nbytes), *this);
  }

  T unwrap() const { return ptr_; }

  T unwrapUnshared() const {
    MOZ_ASSERT(sharedness_ == IsUnshared);
    return ptr_;
  }

  uintptr_t unwrapValue() const { return reinterpret_cast<uintptr_t>(ptr_); }
};

template <typename T>
inline bool operator>=(const SharedMem<T>& a, const SharedMem<T>& b) {
  return a.unwrap() >= b.unwrap();
}

template <typename T>
inline bool operator>=(const void* a, const SharedMem<T>& b) {
  return a >= b.unwrap();
}

template <typename T>
inline bool operator==(const void* a, const SharedMem<T>& b) {
  return a == b.unwrap();
}

template <typename T>
inline bool operator==(const SharedMem<T>& a, decltype(nullptr) b) {
  return a.unwrap() == b;
}

template <typename T>
inline bool operator==(const SharedMem<T>& a, const SharedMem<T>& b) {
  return a.unwrap() == b.unwrap();
}

template <typename T>
inline bool operator!=(const SharedMem<T>& a, decltype(nullptr) b) {
  return a.unwrap() != b;
}

template <typename T>
inline bool operator!=(const SharedMem<T>& a, const SharedMem<T>& b) {
  return a.unwrap() != b.unwrap();
}

template <typename T>
inline bool operator>(const SharedMem<T>& a, const SharedMem<T>& b) {
  return a.unwrap() > b.unwrap();
}

template <typename T>
inline bool operator>(const void* a, const SharedMem<T>& b) {
  return a > b.unwrap();
}

template <typename T>
inline bool operator<=(const SharedMem<T>& a, const SharedMem<T>& b) {
  return a.unwrap() <= b.unwrap();
}

template <typename T>
inline bool operator<=(const void* a, const SharedMem<T>& b) {
  return a <= b.unwrap();
}

template <typename T>
inline bool operator<(const void* a, const SharedMem<T>& b) {
  return a < b.unwrap();
}

#endif  // vm_SharedMem_h