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      1 // Protocol Buffers - Google's data interchange format
      2 // Copyright 2008 Google Inc.  All rights reserved.
      3 // https://developers.google.com/protocol-buffers/
      4 //
      5 // Redistribution and use in source and binary forms, with or without
      6 // modification, are permitted provided that the following conditions are
      7 // met:
      8 //
      9 //     * Redistributions of source code must retain the above copyright
     10 // notice, this list of conditions and the following disclaimer.
     11 //     * Redistributions in binary form must reproduce the above
     12 // copyright notice, this list of conditions and the following disclaimer
     13 // in the documentation and/or other materials provided with the
     14 // distribution.
     15 //     * Neither the name of Google Inc. nor the names of its
     16 // contributors may be used to endorse or promote products derived from
     17 // this software without specific prior written permission.
     18 //
     19 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     20 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     21 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     22 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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     25 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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     27 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     28 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     29 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     30 
     31 // Author: tibell (at) google.com (Johan Tibell)
     32 
     33 #ifndef GOOGLE_PROTOBUF_PYTHON_CPP_SCOPED_PYOBJECT_PTR_H__
     34 #define GOOGLE_PROTOBUF_PYTHON_CPP_SCOPED_PYOBJECT_PTR_H__
     35 
     36 #include <Python.h>
     37 
     38 namespace google {
     39 class ScopedPyObjectPtr {
     40  public:
     41   // Constructor.  Defaults to intializing with NULL.
     42   // There is no way to create an uninitialized ScopedPyObjectPtr.
     43   explicit ScopedPyObjectPtr(PyObject* p = NULL) : ptr_(p) { }
     44 
     45   // Destructor.  If there is a PyObject object, delete it.
     46   ~ScopedPyObjectPtr() {
     47     Py_XDECREF(ptr_);
     48   }
     49 
     50   // Reset.  Deletes the current owned object, if any.
     51   // Then takes ownership of a new object, if given.
     52   // this->reset(this->get()) works.
     53   PyObject* reset(PyObject* p = NULL) {
     54     if (p != ptr_) {
     55       Py_XDECREF(ptr_);
     56       ptr_ = p;
     57     }
     58     return ptr_;
     59   }
     60 
     61   // Releases ownership of the object.
     62   PyObject* release() {
     63     PyObject* p = ptr_;
     64     ptr_ = NULL;
     65     return p;
     66   }
     67 
     68   operator PyObject*() { return ptr_; }
     69 
     70   PyObject* operator->() const  {
     71     assert(ptr_ != NULL);
     72     return ptr_;
     73   }
     74 
     75   PyObject* get() const { return ptr_; }
     76 
     77   Py_ssize_t refcnt() const { return Py_REFCNT(ptr_); }
     78 
     79   void inc() const { Py_INCREF(ptr_); }
     80 
     81   // Comparison operators.
     82   // These return whether a ScopedPyObjectPtr and a raw pointer
     83   // refer to the same object, not just to two different but equal
     84   // objects.
     85   bool operator==(const PyObject* p) const { return ptr_ == p; }
     86   bool operator!=(const PyObject* p) const { return ptr_ != p; }
     87 
     88  private:
     89   PyObject* ptr_;
     90 
     91   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(ScopedPyObjectPtr);
     92 };
     93 
     94 }  // namespace google
     95 #endif  // GOOGLE_PROTOBUF_PYTHON_CPP_SCOPED_PYOBJECT_PTR_H__
     96