include/xplc/delete.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  *
   3  * XPLC - Cross-Platform Lightweight Components
   4  * Copyright (C) 2004, Net Integration Technologies, Inc.
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public License
   8  * as published by the Free Software Foundation; either version 2.1 of
   9  * the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  19  * USA
  20  *
  21  * As a special exception, you may use this file as part of a free
  22  * software library without restriction.  Specifically, if other files
  23  * instantiate templates or use macros or inline functions from this
  24  * file, or you compile this file and link it with other files to
  25  * produce an executable, this file does not by itself cause the
  26  * resulting executable to be covered by the GNU Lesser General Public
  27  * License.  This exception does not however invalidate any other
  28  * reasons why the executable file might be covered by the GNU Lesser
  29  * General Public License.
  30  */
  31
  32 #ifndef __XPLC_DELETE_H__
  33 #define __XPLC_DELETE_H__
  34
  35 #if defined(__GNUC__) && __GNUC__ > 3
  36 # pragma GCC system_header
  37 #endif
  38
  39 /** \file
  40  *
  41  * Include this file right after IObject.h (or instead of) to detect
  42  * accidental uses of "delete" on an %XPLC interface. Use "xplcdelete"
  43  * instead of "delete" when you know what you are doing.
  44  */
  45
  46 #include <new>
  47 #include <memory>
  48
  49 #ifdef __XPLC_IOBJECT_H__
  50 #error "<xplc/delete.h> has to be included before <xplc/IObject.h>."
  51 #endif
  52
  53 #include <xplc/IObject.h>
  54
  55 /**
  56  * \defgroup DeleteDetector This is the "delete detector".
  57  */
  58
  59 /// \ingroup DeleteDetector
  60 class CheckIObject {};
  61 class CheckIObjectOk {};
  62 /// \ingroup DeleteDetector
  63 class CheckIObjectOkVector {};
  64
  65 template<class T>
  66 class ConversionIObject
  67 {
  68 public:
  69   //@{
  70   typedef char Yes;
  71   /// \ingroup DeleteDetector
  72   struct No { char dummy[2]; };
  73   static T* from;
  74   static Yes test(const IObject*);
  75   static No test(...);
  76   //@}
  77 };
  78
  79 template<bool>
  80 struct XPLC_CTAssert;
  81 template<>
  82 /// \ingroup DeleteDetector
  83 struct XPLC_CTAssert<true> {};
  84
  85 template<class T>
  86 inline void operator&&(CheckIObject, const T* obj) {
  87   static_cast<void>(sizeof(XPLC_CTAssert<(sizeof(ConversionIObject<T>::test(ConversionIObject<T>::from)) != sizeof(typename ConversionIObject<T>::Yes))>));
  88   delete obj;
  89 }
  90
  91 template<class T>
  92 inline void operator&&(CheckIObjectOk, const T* obj) {
  93   delete obj;
  94 }
  95
  96 template<class T>
  97 inline void operator&&(CheckIObjectOkVector, const T* obj) {
  98   delete[] obj;
  99 }
 100
 101
 102 /**
 103  * Undefine xplcdelete. <xplc/utils.h> defines xplcdelete, we should
 104  * undo this, in case it has been included before.
 105  */
 106 #undef xplcdelete
 107
 108 /**
 109  * Macro used to indicate a valid use of the delete keyword with an
 110  * XPLC interface. In some cases, you really need to use delete on an
 111  * object that derives from IObject. In those cases, use "xplcdelete"
 112  * instead of "delete".
 113  */
 114 #define xplcdelete CheckIObjectOk() &&
 115
 116 /**
 117  * Overriding the delete keyword. This replaces the delete keyword
 118  * with an invocation of the operator&& using a specific marker class
 119  * as the left operand, allowing it to be templated on the right
 120  * operand.
 121  */
 122 #define delete CheckIObject() &&
 123
 124 /**
 125  * Remplacement for delete[]. Because we cannot capture usage of
 126  * delete[] using macros, we have to add a replacement for it,
 127  * unfortunately.
 128  */
 129 #define deletev CheckIObjectOkVector() &&
 130
 131 #endif /* __XPLC_DELETE_H__ */