From d36c0c538a545fac5d9db6ba65c525246d4efa95 Mon Sep 17 00:00:00 2001
From: Feng Xiao <xfxyjwf@gmail.com>
Date: Wed, 29 Mar 2017 14:32:48 -0700
Subject: Down-integrate from google3.

---
 python/google/protobuf/pyext/scoped_pyobject_ptr.h | 59 +++++++++++++---------
 1 file changed, 34 insertions(+), 25 deletions(-)

(limited to 'python/google/protobuf/pyext/scoped_pyobject_ptr.h')

diff --git a/python/google/protobuf/pyext/scoped_pyobject_ptr.h b/python/google/protobuf/pyext/scoped_pyobject_ptr.h
index a128cd4c..a2afa7f1 100644
--- a/python/google/protobuf/pyext/scoped_pyobject_ptr.h
+++ b/python/google/protobuf/pyext/scoped_pyobject_ptr.h
@@ -36,61 +36,70 @@
 #include <google/protobuf/stubs/common.h>
 
 #include <Python.h>
-
 namespace google {
-class ScopedPyObjectPtr {
+namespace protobuf {
+namespace python {
+
+// Owns a python object and decrements the reference count on destruction.
+// This class is not threadsafe.
+template <typename PyObjectStruct>
+class ScopedPythonPtr {
  public:
-  // Constructor.  Defaults to initializing with NULL.
-  // There is no way to create an uninitialized ScopedPyObjectPtr.
-  explicit ScopedPyObjectPtr(PyObject* p = NULL) : ptr_(p) { }
+  // Takes the ownership of the specified object to ScopedPythonPtr.
+  // The reference count of the specified py_object is not incremented.
+  explicit ScopedPythonPtr(PyObjectStruct* py_object = NULL)
+      : ptr_(py_object) {}
 
-  // Destructor.  If there is a PyObject object, delete it.
-  ~ScopedPyObjectPtr() {
-    Py_XDECREF(ptr_);
-  }
+  // If a PyObject is owned, decrement its reference count.
+  ~ScopedPythonPtr() { Py_XDECREF(ptr_); }
 
-  // Reset.  Deletes the current owned object, if any.
-  // Then takes ownership of a new object, if given.
+  // Deletes the current owned object, if any.
+  // Then takes ownership of a new object without incrementing the reference
+  // count.
   // This function must be called with a reference that you own.
   //   this->reset(this->get()) is wrong!
   //   this->reset(this->release()) is OK.
-  PyObject* reset(PyObject* p = NULL) {
+  PyObjectStruct* reset(PyObjectStruct* p = NULL) {
     Py_XDECREF(ptr_);
     ptr_ = p;
     return ptr_;
   }
 
-  // Releases ownership of the object.
+  // Releases ownership of the object without decrementing the reference count.
   // The caller now owns the returned reference.
-  PyObject* release() {
+  PyObjectStruct* release() {
     PyObject* p = ptr_;
     ptr_ = NULL;
     return p;
   }
 
-  PyObject* operator->() const  {
+  PyObjectStruct* operator->() const {
     assert(ptr_ != NULL);
     return ptr_;
   }
 
-  PyObject* get() const { return ptr_; }
+  PyObjectStruct* get() const { return ptr_; }
 
-  Py_ssize_t refcnt() const { return Py_REFCNT(ptr_); }
+  PyObject* as_pyobject() const { return reinterpret_cast<PyObject*>(ptr_); }
 
+  // Increments the reference count fo the current object.
+  // Should not be called when no object is held.
   void inc() const { Py_INCREF(ptr_); }
 
-  // Comparison operators.
-  // These return whether a ScopedPyObjectPtr and a raw pointer
-  // refer to the same object, not just to two different but equal
-  // objects.
-  bool operator==(const PyObject* p) const { return ptr_ == p; }
-  bool operator!=(const PyObject* p) const { return ptr_ != p; }
+  // True when a ScopedPyObjectPtr and a raw pointer refer to the same object.
+  // Comparison operators are non reflexive.
+  bool operator==(const PyObjectStruct* p) const { return ptr_ == p; }
+  bool operator!=(const PyObjectStruct* p) const { return ptr_ != p; }
 
  private:
-  PyObject* ptr_;
+  PyObjectStruct* ptr_;
 
-  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(ScopedPyObjectPtr);
+  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(ScopedPythonPtr);
 };
 
+typedef ScopedPythonPtr<PyObject> ScopedPyObjectPtr;
+
+}  // namespace python
+}  // namespace protobuf
 }  // namespace google
 #endif  // GOOGLE_PROTOBUF_PYTHON_CPP_SCOPED_PYOBJECT_PTR_H__
-- 
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