scoped_pyobject_ptr.h

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// Author: tibell@google.com (Johan Tibell)

#ifndef GOOGLE_PROTOBUF_PYTHON_CPP_SCOPED_PYOBJECT_PTR_H__
#define GOOGLE_PROTOBUF_PYTHON_CPP_SCOPED_PYOBJECT_PTR_H__

#include <google/protobuf/stubs/common.h>

#include <Python.h>

namespace google {
class ScopedPyObjectPtr {
 public:
  // Constructor.  Defaults to initializing with NULL.
  // There is no way to create an uninitialized ScopedPyObjectPtr.
  explicit ScopedPyObjectPtr(PyObject* p = NULL) : ptr_(p) { }

  // Destructor.  If there is a PyObject object, delete it.
  ~ScopedPyObjectPtr() {
    Py_XDECREF(ptr_);
  }

  // Reset.  Deletes the current owned object, if any.
  // Then takes ownership of a new object, if given.
  // 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) {
    Py_XDECREF(ptr_);
    ptr_ = p;
    return ptr_;
  }

  // Releases ownership of the object.
  // The caller now owns the returned reference.
  PyObject* release() {
    PyObject* p = ptr_;
    ptr_ = NULL;
    return p;
  }

  PyObject* operator->() const  {
    assert(ptr_ != NULL);
    return ptr_;
  }

  PyObject* get() const { return ptr_; }

  Py_ssize_t refcnt() const { return Py_REFCNT(ptr_); }

  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; }

 private:
  PyObject* ptr_;

  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(ScopedPyObjectPtr);
};

}  // namespace google
#endif  // GOOGLE_PROTOBUF_PYTHON_CPP_SCOPED_PYOBJECT_PTR_H__