The Tor Browser: xpcom/base/StaticPtr.h@b8a032363ba2 (annotated)

xpcom/base/StaticPtr.h@b8a032363ba2 (annotated)

xpcom/base/StaticPtr.h

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* vim: set sw=2 ts=8 et ft=cpp : */
 /* 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 mozilla_StaticPtr_h
 #define mozilla_StaticPtr_h
 #include "mozilla/Assertions.h"
 #include "mozilla/NullPtr.h"
 namespace mozilla {
 /**
  * StaticAutoPtr and StaticRefPtr are like nsAutoPtr and nsRefPtr, except they
  * are suitable for use as global variables.
  *
  * In particular, a global instance of Static{Auto,Ref}Ptr doesn't cause the
  * compiler to emit  a static initializer (in release builds, anyway).
  *
  * In order to accomplish this, Static{Auto,Ref}Ptr must have a trivial
  * constructor and destructor.  As a consequence, it cannot initialize its raw
  * pointer to 0 on construction, and it cannot delete/release its raw pointer
  * upon destruction.
  *
  * Since the compiler guarantees that all global variables are initialized to
  * 0, these trivial constructors are safe, so long as you use
  * Static{Auto,Ref}Ptr as a global variable.  If you use Static{Auto,Ref}Ptr as
  * a stack variable or as a class instance variable, you will get what you
  * deserve.
  *
  * Static{Auto,Ref}Ptr have a limited interface as compared to ns{Auto,Ref}Ptr;
  * this is intentional, since their range of acceptable uses is smaller.
  */
 template<class T>
 class StaticAutoPtr
 {
   public:
     // In debug builds, check that mRawPtr is initialized for us as we expect
     // by the compiler.  In non-debug builds, don't declare a constructor
     // so that the compiler can see that the constructor is trivial.
 #ifdef DEBUG
     StaticAutoPtr()
     {
       MOZ_ASSERT(!mRawPtr);
     }
 #endif
     StaticAutoPtr<T>& operator=(T* rhs)
     {
       Assign(rhs);
       return *this;
     }
     T* get() const
     {
       return mRawPtr;
     }
     operator T*() const
     {
       return get();
     }
     T* operator->() const
     {
       MOZ_ASSERT(mRawPtr);
       return get();
     }
     T& operator*() const
     {
       return *get();
     }
   private:
     // Disallow copy constructor, but only in debug mode.  We only define
     // a default constructor in debug mode (see above); if we declared
     // this constructor always, the compiler wouldn't generate a trivial
     // default constructor for us in non-debug mode.
 #ifdef DEBUG
     StaticAutoPtr(StaticAutoPtr<T> &other);
 #endif
     void Assign(T* newPtr)
     {
       MOZ_ASSERT(!newPtr || mRawPtr != newPtr);
       T* oldPtr = mRawPtr;
       mRawPtr = newPtr;
       delete oldPtr;
     }
     T* mRawPtr;
 };
 template<class T>
 class StaticRefPtr
 {
 public:
   // In debug builds, check that mRawPtr is initialized for us as we expect
   // by the compiler.  In non-debug builds, don't declare a constructor
   // so that the compiler can see that the constructor is trivial.
 #ifdef DEBUG
   StaticRefPtr()
   {
     MOZ_ASSERT(!mRawPtr);
   }
 #endif
   StaticRefPtr<T>& operator=(T* rhs)
   {
     AssignWithAddref(rhs);
     return *this;
   }
   StaticRefPtr<T>& operator=(const StaticRefPtr<T>& rhs)
   {
     return (this = rhs.mRawPtr);
   }
   T* get() const
   {
     return mRawPtr;
   }
   operator T*() const
   {
     return get();
   }
   T* operator->() const
   {
     MOZ_ASSERT(mRawPtr);
     return get();
   }
   T& operator*() const
   {
     return *get();
   }
 private:
   void AssignWithAddref(T* newPtr)
   {
     if (newPtr) {
       newPtr->AddRef();
     }
     AssignAssumingAddRef(newPtr);
   }
   void AssignAssumingAddRef(T* newPtr)
   {
     T* oldPtr = mRawPtr;
     mRawPtr = newPtr;
     if (oldPtr) {
       oldPtr->Release();
     }
   }
   T* mRawPtr;
 };
 namespace StaticPtr_internal {
 class Zero;
 } // namespace StaticPtr_internal
 #define REFLEXIVE_EQUALITY_OPERATORS(type1, type2, eq_fn, ...) \
   template<__VA_ARGS__>                                        \
   inline bool                                                  \
   operator==(type1 lhs, type2 rhs)                             \
   {                                                            \
     return eq_fn;                                              \
   }                                                            \
                                                                \
   template<__VA_ARGS__>                                        \
   inline bool                                                  \
   operator==(type2 lhs, type1 rhs)                             \
   {                                                            \
     return rhs == lhs;                                         \
   }                                                            \
                                                                \
   template<__VA_ARGS__>                                        \
   inline bool                                                  \
   operator!=(type1 lhs, type2 rhs)                             \
   {                                                            \
     return !(lhs == rhs);                                      \
   }                                                            \
                                                                \
   template<__VA_ARGS__>                                        \
   inline bool                                                  \
   operator!=(type2 lhs, type1 rhs)                             \
   {                                                            \
     return !(lhs == rhs);                                      \
   }
 // StaticAutoPtr (in)equality operators
 template<class T, class U>
 inline bool
 operator==(const StaticAutoPtr<T>& lhs, const StaticAutoPtr<U>& rhs)
 {
   return lhs.get() == rhs.get();
 }
 template<class T, class U>
 inline bool
 operator!=(const StaticAutoPtr<T>& lhs, const StaticAutoPtr<U>& rhs)
 {
   return !(lhs == rhs);
 }
 REFLEXIVE_EQUALITY_OPERATORS(const StaticAutoPtr<T>&, const U*,
                              lhs.get() == rhs, class T, class U)
 REFLEXIVE_EQUALITY_OPERATORS(const StaticAutoPtr<T>&, U*,
                              lhs.get() == rhs, class T, class U)
 // Let us compare StaticAutoPtr to 0.
 REFLEXIVE_EQUALITY_OPERATORS(const StaticAutoPtr<T>&, StaticPtr_internal::Zero*,
                              lhs.get() == nullptr, class T)
 // StaticRefPtr (in)equality operators
 template<class T, class U>
 inline bool
 operator==(const StaticRefPtr<T>& lhs, const StaticRefPtr<U>& rhs)
 {
   return lhs.get() == rhs.get();
 }
 template<class T, class U>
 inline bool
 operator!=(const StaticRefPtr<T>& lhs, const StaticRefPtr<U>& rhs)
 {
   return !(lhs == rhs);
 }
 REFLEXIVE_EQUALITY_OPERATORS(const StaticRefPtr<T>&, const U*,
                              lhs.get() == rhs, class T, class U)
 REFLEXIVE_EQUALITY_OPERATORS(const StaticRefPtr<T>&, U*,
                              lhs.get() == rhs, class T, class U)
 // Let us compare StaticRefPtr to 0.
 REFLEXIVE_EQUALITY_OPERATORS(const StaticRefPtr<T>&, StaticPtr_internal::Zero*,
                              lhs.get() == nullptr, class T)
 #undef REFLEXIVE_EQUALITY_OPERATORS
 } // namespace mozilla
 #endif

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xpcom/base/StaticPtr.h@b8a032363ba2 (annotated)

xpcom/base/StaticPtr.h