connectivity/source/inc/java/LocalRef.hxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
   4  *
   5  * This Source Code Form is subject to the terms of the Mozilla Public
   6  * License, v. 2.0. If a copy of the MPL was not distributed with this
   7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   8  *
   9  * This file incorporates work covered by the following license notice:
  10  *
  11  *   Licensed to the Apache Software Foundation (ASF) under one or more
  12  *   contributor license agreements. See the NOTICE file distributed
  13  *   with this work for additional information regarding copyright
  14  *   ownership. The ASF licenses this file to you under the Apache
  15  *   License, Version 2.0 (the "License"); you may not use this file
  16  *   except in compliance with the License. You may obtain a copy of
  17  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  18  */
  19
  20 #ifndef INCLUDED_CONNECTIVITY_SOURCE_INC_JAVA_LOCALREF_HXX
  21 #define INCLUDED_CONNECTIVITY_SOURCE_INC_JAVA_LOCALREF_HXX
  22
  23 #include <jni.h>
  24
  25
  26 namespace connectivity::jdbc
  27 {
  28
  29     /** helper class to hold a local ref to a JNI object
  30
  31         Note that this class never actually calls NewLocalRef. It is assumed that all objects
  32         passed are already acquired with a local ref (as it usually is the case if you obtain
  33         the object from a JNI method).
  34     */
  35     template< typename T >
  36     class LocalRef final
  37     {
  38     public:
  39         explicit LocalRef( JNIEnv& environment )
  40             :m_environment( environment )
  41             ,m_object( nullptr )
  42         {
  43         }
  44
  45         LocalRef( JNIEnv& environment, T object )
  46             :m_environment( environment )
  47             ,m_object( object )
  48         {
  49         }
  50
  51         ~LocalRef()
  52         {
  53             reset();
  54         }
  55
  56         T release()
  57         {
  58             T t = m_object;
  59             m_object = nullptr;
  60             return t;
  61         }
  62
  63         void set( T object ) { reset(); m_object = object; }
  64
  65         void reset()
  66         {
  67             if ( m_object != nullptr )
  68             {
  69                 m_environment.DeleteLocalRef( m_object );
  70                 m_object = nullptr;
  71             }
  72         }
  73
  74         JNIEnv& env() const { return m_environment; }
  75         T       get() const { return m_object; }
  76         bool    is()  const { return m_object != nullptr; }
  77
  78     private:
  79         LocalRef(LocalRef const &) = delete;
  80         LocalRef& operator =(LocalRef const &) = delete;
  81
  82         JNIEnv& m_environment;
  83         T       m_object;
  84     };
  85
  86
  87 } // namespace connectivity::jdbc
  88
  89
  90 #endif // INCLUDED_CONNECTIVITY_SOURCE_INC_JAVA_LOCALREF_HXX
  91
  92 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */