Revert https://codereview.chromium.org/1291903002 (protobuf roll).

third_party/protobuf/src/google/protobuf/stubs/shared_ptr.h

Index: third_party/protobuf/src/google/protobuf/stubs/shared_ptr.h
diff --git a/third_party/protobuf/src/google/protobuf/stubs/shared_ptr.h b/third_party/protobuf/src/google/protobuf/stubs/shared_ptr.h
deleted file mode 100644
index d250bf4d33850d0a48507d10d1bcfd181cc2d853..0000000000000000000000000000000000000000
--- a/third_party/protobuf/src/google/protobuf/stubs/shared_ptr.h
+++ /dev/null
@@ -1,470 +0,0 @@
-// Protocol Buffers - Google's data interchange format
-// Copyright 2014 Google Inc.  All rights reserved.
-// https://developers.google.com/protocol-buffers/
-//
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-// notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-// copyright notice, this list of conditions and the following disclaimer
-// in the documentation and/or other materials provided with the
-// distribution.
-//     * Neither the name of Google Inc. nor the names of its
-// contributors may be used to endorse or promote products derived from
-// this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-// from google3/util/gtl/shared_ptr.h
-
-#ifndef GOOGLE_PROTOBUF_STUBS_SHARED_PTR_H__
-#define GOOGLE_PROTOBUF_STUBS_SHARED_PTR_H__
-
-#include <google/protobuf/stubs/atomicops.h>
-
-#include <algorithm>  // for swap
-#include <stddef.h>
-#include <memory>
-
-namespace google {
-namespace protobuf {
-namespace internal {
-
-// Alias to std::shared_ptr for any C++11 platform,
-// and for any supported MSVC compiler.
-#if !defined(UTIL_GTL_USE_STD_SHARED_PTR) && \
-    (defined(COMPILER_MSVC) || defined(LANG_CXX11))
-#define UTIL_GTL_USE_STD_SHARED_PTR 1
-#endif
-
-#if defined(UTIL_GTL_USE_STD_SHARED_PTR) && UTIL_GTL_USE_STD_SHARED_PTR
-
-// These are transitional.  They will be going away soon.
-// Please just #include <memory> and just type std::shared_ptr yourself, instead
-// of relying on this file.
-//
-// Migration doc: http://go/std-shared-ptr-lsc
-using std::enable_shared_from_this;
-using std::shared_ptr;
-using std::static_pointer_cast;
-using std::weak_ptr;
-
-#else  // below, UTIL_GTL_USE_STD_SHARED_PTR not set or set to 0.
-
-// For everything else there is the google3 implementation.
-inline bool RefCountDec(volatile Atomic32 *ptr) {
-  return Barrier_AtomicIncrement(ptr, -1) != 0;
-}
-
-inline void RefCountInc(volatile Atomic32 *ptr) {
-  NoBarrier_AtomicIncrement(ptr, 1);
-}
-
-template <typename T> class shared_ptr;
-template <typename T> class weak_ptr;
-
-// This class is an internal implementation detail for shared_ptr. If two
-// shared_ptrs point to the same object, they also share a control block.
-// An "empty" shared_pointer refers to NULL and also has a NULL control block.
-// It contains all of the state that's needed for reference counting or any
-// other kind of resource management. In this implementation the control block
-// happens to consist of two atomic words, the reference count (the number
-// of shared_ptrs that share ownership of the object) and the weak count
-// (the number of weak_ptrs that observe the object, plus 1 if the
-// refcount is nonzero).
-//
-// The "plus 1" is to prevent a race condition in the shared_ptr and
-// weak_ptr destructors. We need to make sure the control block is
-// only deleted once, so we need to make sure that at most one
-// object sees the weak count decremented from 1 to 0.
-class SharedPtrControlBlock {
-  template <typename T> friend class shared_ptr;
-  template <typename T> friend class weak_ptr;
- private:
-  SharedPtrControlBlock() : refcount_(1), weak_count_(1) { }
-  Atomic32 refcount_;
-  Atomic32 weak_count_;
-};
-
-// Forward declaration. The class is defined below.
-template <typename T> class enable_shared_from_this;
-
-template <typename T>
-class shared_ptr {
-  template <typename U> friend class weak_ptr;
- public:
-  typedef T element_type;
-
-  shared_ptr() : ptr_(NULL), control_block_(NULL) {}
-
-  explicit shared_ptr(T* ptr)
-      : ptr_(ptr),
-        control_block_(ptr != NULL ? new SharedPtrControlBlock : NULL) {
-    // If p is non-null and T inherits from enable_shared_from_this, we
-    // set up the data that shared_from_this needs.
-    MaybeSetupWeakThis(ptr);
-  }
-
-  // Copy constructor: makes this object a copy of ptr, and increments
-  // the reference count.
-  template <typename U>
-  shared_ptr(const shared_ptr<U>& ptr)
-      : ptr_(NULL),
-        control_block_(NULL) {
-    Initialize(ptr);
-  }
-  // Need non-templated version to prevent the compiler-generated default
-  shared_ptr(const shared_ptr<T>& ptr)
-      : ptr_(NULL),
-        control_block_(NULL) {
-    Initialize(ptr);
-  }
-
-  // Assignment operator. Replaces the existing shared_ptr with ptr.
-  // Increment ptr's reference count and decrement the one being replaced.
-  template <typename U>
-  shared_ptr<T>& operator=(const shared_ptr<U>& ptr) {
-    if (ptr_ != ptr.ptr_) {
-      shared_ptr<T> me(ptr);   // will hold our previous state to be destroyed.
-      swap(me);
-    }
-    return *this;
-  }
-
-  // Need non-templated version to prevent the compiler-generated default
-  shared_ptr<T>& operator=(const shared_ptr<T>& ptr) {
-    if (ptr_ != ptr.ptr_) {
-      shared_ptr<T> me(ptr);   // will hold our previous state to be destroyed.
-      swap(me);
-    }
-    return *this;
-  }
-
-  // TODO(austern): Consider providing this constructor. The draft C++ standard
-  // (20.8.10.2.1) includes it. However, it says that this constructor throws
-  // a bad_weak_ptr exception when ptr is expired. Is it better to provide this
-  // constructor and make it do something else, like fail with a CHECK, or to
-  // leave this constructor out entirely?
-  //
-  // template <typename U>
-  // shared_ptr(const weak_ptr<U>& ptr);
-
-  ~shared_ptr() {
-    if (ptr_ != NULL) {
-      if (!RefCountDec(&control_block_->refcount_)) {
-        delete ptr_;
-
-        // weak_count_ is defined as the number of weak_ptrs that observe
-        // ptr_, plus 1 if refcount_ is nonzero.
-        if (!RefCountDec(&control_block_->weak_count_)) {
-          delete control_block_;
-        }
-      }
-    }
-  }
-
-  // Replaces underlying raw pointer with the one passed in.  The reference
-  // count is set to one (or zero if the pointer is NULL) for the pointer
-  // being passed in and decremented for the one being replaced.
-  //
-  // If you have a compilation error with this code, make sure you aren't
-  // passing NULL, nullptr, or 0 to this function.  Call reset without an
-  // argument to reset to a null ptr.
-  template <typename Y>
-  void reset(Y* p) {
-    if (p != ptr_) {
-      shared_ptr<T> tmp(p);
-      tmp.swap(*this);
-    }
-  }
-
-  void reset() {
-    reset(static_cast<T*>(NULL));
-  }
-
-  // Exchanges the contents of this with the contents of r.  This function
-  // supports more efficient swapping since it eliminates the need for a
-  // temporary shared_ptr object.
-  void swap(shared_ptr<T>& r) {
-    using std::swap;  // http://go/using-std-swap
-    swap(ptr_, r.ptr_);
-    swap(control_block_, r.control_block_);
-  }
-
-  // The following function is useful for gaining access to the underlying
-  // pointer when a shared_ptr remains in scope so the reference-count is
-  // known to be > 0 (e.g. for parameter passing).
-  T* get() const {
-    return ptr_;
-  }
-
-  T& operator*() const {
-    return *ptr_;
-  }
-
-  T* operator->() const {
-    return ptr_;
-  }
-
-  long use_count() const {
-    return control_block_ ? control_block_->refcount_ : 1;
-  }
-
-  bool unique() const {
-    return use_count() == 1;
-  }
-
- private:
-  // If r is non-empty, initialize *this to share ownership with r,
-  // increasing the underlying reference count.
-  // If r is empty, *this remains empty.
-  // Requires: this is empty, namely this->ptr_ == NULL.
-  template <typename U>
-  void Initialize(const shared_ptr<U>& r) {
-    // This performs a static_cast on r.ptr_ to U*, which is a no-op since it
-    // is already a U*. So initialization here requires that r.ptr_ is
-    // implicitly convertible to T*.
-    InitializeWithStaticCast<U>(r);
-  }
-
-  // Initializes *this as described in Initialize, but additionally performs a
-  // static_cast from r.ptr_ (V*) to U*.
-  // NOTE(gfc): We'd need a more general form to support const_pointer_cast and
-  // dynamic_pointer_cast, but those operations are sufficiently discouraged
-  // that supporting static_pointer_cast is sufficient.
-  template <typename U, typename V>
-  void InitializeWithStaticCast(const shared_ptr<V>& r) {
-    if (r.control_block_ != NULL) {
-      RefCountInc(&r.control_block_->refcount_);
-
-      ptr_ = static_cast<U*>(r.ptr_);
-      control_block_ = r.control_block_;
-    }
-  }
-
-  // Helper function for the constructor that takes a raw pointer. If T
-  // doesn't inherit from enable_shared_from_this<T> then we have nothing to
-  // do, so this function is trivial and inline. The other version is declared
-  // out of line, after the class definition of enable_shared_from_this.
-  void MaybeSetupWeakThis(enable_shared_from_this<T>* ptr);
-  void MaybeSetupWeakThis(...) { }
-
-  T* ptr_;
-  SharedPtrControlBlock* control_block_;
-
-#ifndef SWIG
-  template <typename U>
-  friend class shared_ptr;
-
-  template <typename U, typename V>
-  friend shared_ptr<U> static_pointer_cast(const shared_ptr<V>& rhs);
-#endif
-};
-
-// Matches the interface of std::swap as an aid to generic programming.
-template <typename T> void swap(shared_ptr<T>& r, shared_ptr<T>& s) {
-  r.swap(s);
-}
-
-template <typename T, typename U>
-shared_ptr<T> static_pointer_cast(const shared_ptr<U>& rhs) {
-  shared_ptr<T> lhs;
-  lhs.template InitializeWithStaticCast<T>(rhs);
-  return lhs;
-}
-
-// See comments at the top of the file for a description of why this
-// class exists, and the draft C++ standard (as of July 2009 the
-// latest draft is N2914) for the detailed specification.
-template <typename T>
-class weak_ptr {
-  template <typename U> friend class weak_ptr;
- public:
-  typedef T element_type;
-
-  // Create an empty (i.e. already expired) weak_ptr.
-  weak_ptr() : ptr_(NULL), control_block_(NULL) { }
-
-  // Create a weak_ptr that observes the same object that ptr points
-  // to.  Note that there is no race condition here: we know that the
-  // control block can't disappear while we're looking at it because
-  // it is owned by at least one shared_ptr, ptr.
-  template <typename U> weak_ptr(const shared_ptr<U>& ptr) {
-    CopyFrom(ptr.ptr_, ptr.control_block_);
-  }
-
-  // Copy a weak_ptr. The object it points to might disappear, but we
-  // don't care: we're only working with the control block, and it can't
-  // disappear while we're looking at because it's owned by at least one
-  // weak_ptr, ptr.
-  template <typename U> weak_ptr(const weak_ptr<U>& ptr) {
-    CopyFrom(ptr.ptr_, ptr.control_block_);
-  }
-
-  // Need non-templated version to prevent default copy constructor
-  weak_ptr(const weak_ptr& ptr) {
-    CopyFrom(ptr.ptr_, ptr.control_block_);
-  }
-
-  // Destroy the weak_ptr. If no shared_ptr owns the control block, and if
-  // we are the last weak_ptr to own it, then it can be deleted. Note that
-  // weak_count_ is defined as the number of weak_ptrs sharing this control
-  // block, plus 1 if there are any shared_ptrs. We therefore know that it's
-  // safe to delete the control block when weak_count_ reaches 0, without
-  // having to perform any additional tests.
-  ~weak_ptr() {
-    if (control_block_ != NULL &&
-        !RefCountDec(&control_block_->weak_count_)) {
-      delete control_block_;
-    }
-  }
-
-  weak_ptr& operator=(const weak_ptr& ptr) {
-    if (&ptr != this) {
-      weak_ptr tmp(ptr);
-      tmp.swap(*this);
-    }
-    return *this;
-  }
-  template <typename U> weak_ptr& operator=(const weak_ptr<U>& ptr) {
-    weak_ptr tmp(ptr);
-    tmp.swap(*this);
-    return *this;
-  }
-  template <typename U> weak_ptr& operator=(const shared_ptr<U>& ptr) {
-    weak_ptr tmp(ptr);
-    tmp.swap(*this);
-    return *this;
-  }
-
-  void swap(weak_ptr& ptr) {
-    using std::swap;  // http://go/using-std-swap
-    swap(ptr_, ptr.ptr_);
-    swap(control_block_, ptr.control_block_);
-  }
-
-  void reset() {
-    weak_ptr tmp;
-    tmp.swap(*this);
-  }
-
-  // Return the number of shared_ptrs that own the object we are observing.
-  // Note that this number can be 0 (if this pointer has expired).
-  long use_count() const {
-    return control_block_ != NULL ? control_block_->refcount_ : 0;
-  }
-
-  bool expired() const { return use_count() == 0; }
-
-  // Return a shared_ptr that owns the object we are observing. If we
-  // have expired, the shared_ptr will be empty. We have to be careful
-  // about concurrency, though, since some other thread might be
-  // destroying the last owning shared_ptr while we're in this
-  // function.  We want to increment the refcount only if it's nonzero
-  // and get the new value, and we want that whole operation to be
-  // atomic.
-  shared_ptr<T> lock() const {
-    shared_ptr<T> result;
-    if (control_block_ != NULL) {
-      Atomic32 old_refcount;
-      do {
-        old_refcount = control_block_->refcount_;
-        if (old_refcount == 0)
-          break;
-      } while (old_refcount !=
-               NoBarrier_CompareAndSwap(
-                   &control_block_->refcount_, old_refcount,
-                   old_refcount + 1));
-      if (old_refcount > 0) {
-        result.ptr_ = ptr_;
-        result.control_block_ = control_block_;
-      }
-    }
-
-    return result;
-  }
-
- private:
-  void CopyFrom(T* ptr, SharedPtrControlBlock* control_block) {
-    ptr_ = ptr;
-    control_block_ = control_block;
-    if (control_block_ != NULL)
-      RefCountInc(&control_block_->weak_count_);
-  }
-
- private:
-  element_type* ptr_;
-  SharedPtrControlBlock* control_block_;
-};
-
-template <typename T> void swap(weak_ptr<T>& r, weak_ptr<T>& s) {
-  r.swap(s);
-}
-
-// See comments at the top of the file for a description of why this class
-// exists, and section 20.8.10.5 of the draft C++ standard (as of July 2009
-// the latest draft is N2914) for the detailed specification.
-template <typename T>
-class enable_shared_from_this {
-  friend class shared_ptr<T>;
- public:
-  // Precondition: there must be a shared_ptr that owns *this and that was
-  // created, directly or indirectly, from a raw pointer of type T*. (The
-  // latter part of the condition is technical but not quite redundant; it
-  // rules out some complicated uses involving inheritance hierarchies.)
-  shared_ptr<T> shared_from_this() {
-    // Behavior is undefined if the precondition isn't satisfied; we choose
-    // to die with a CHECK failure.
-    CHECK(!weak_this_.expired()) << "No shared_ptr owns this object";
-    return weak_this_.lock();
-  }
-  shared_ptr<const T> shared_from_this() const {
-    CHECK(!weak_this_.expired()) << "No shared_ptr owns this object";
-    return weak_this_.lock();
-  }
-
- protected:
-  enable_shared_from_this() { }
-  enable_shared_from_this(const enable_shared_from_this& other) { }
-  enable_shared_from_this& operator=(const enable_shared_from_this& other) {
-    return *this;
-  }
-  ~enable_shared_from_this() { }
-
- private:
-  weak_ptr<T> weak_this_;
-};
-
-// This is a helper function called by shared_ptr's constructor from a raw
-// pointer. If T inherits from enable_shared_from_this<T>, it sets up
-// weak_this_ so that shared_from_this works correctly. If T does not inherit
-// from weak_this we get a different overload, defined inline, which does
-// nothing.
-template<typename T>
-void shared_ptr<T>::MaybeSetupWeakThis(enable_shared_from_this<T>* ptr) {
-  if (ptr) {
-    CHECK(ptr->weak_this_.expired()) << "Object already owned by a shared_ptr";
-    ptr->weak_this_ = *this;
-  }
-}
-
-#endif  // UTIL_GTL_USE_STD_SHARED_PTR
-
-}  // internal
-}  // namespace protobuf
-}  // namespace google
-
-#endif  // GOOGLE_PROTOBUF_STUBS_SHARED_PTR_H__