1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296
|
/*------------------------------------------------------------------------------
Copyright (c) 2000-2007 Tyrell Corporation. All rights reserved.
Tyrell DarkIce
File : Ref.h
Version : $Revision: 474 $
Author : $Author: rafael@riseup.net $
Location : $HeadURL$
Copyright notice:
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 3
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
------------------------------------------------------------------------------*/
#ifndef REF_H
#define REF_H
#ifndef __cplusplus
#error This is a C++ include file
#endif
/* ============================================================ include files */
#include "Exception.h"
/* ================================================================ constants */
/* =================================================================== macros */
/* =============================================================== data types */
/**
* Java-like object reference class.
* Objects used with this reference class have to be descandents
* of class Referable.
*
* sample usage:
*
* <pre>
* #include "Ref.h"
* #include "Referable.h"
*
* class A : public virtual Referable;
*
* ...
*
* A * a = new A();
* Ref<A> ref1 = a; // 1 reference to a
* Ref<A> ref2 = ref1; // 2 references to a
*
* ref1 = 0; // 1 reference to a
* ref2 = 0; // at this point object a is destroyed
* </pre>
*
* Based on Tima Saarinen's work,
* http://gamma.nic.fi/~timosa/comp/refcount.html
*
* @ref Referable
*
* @author $Author: rafael@riseup.net $
* @version $Revision: 474 $
*/
template <class T>
class Ref
{
private:
/**
* The object referenced by this Ref.
* Must be a descandant of Referable.
*/
T* object;
protected:
public:
/**
* Default constructor.
*/
inline
Ref ( void ) throw ()
{
object = NULL;
}
/**
* Copy constructor.
*
* @param other the Ref to copy.
* @exception Exception
*/
inline
Ref ( const Ref<T> & other ) throw ( Exception )
{
object = NULL;
set( other.object);
}
/**
* Constructor based on an object to reference.
*
* @param obj the object to reference.
* @exception Exception
*/
inline
Ref ( T * obj ) throw ( Exception )
{
object = obj;
obj->increaseReferenceCount();
}
/**
* Destructor.
*
* @exception Exception
*/
inline virtual
~Ref ( void ) throw ( Exception )
{
set( 0 );
}
/**
* Operator overload to make the reference seem like a pointer.
*
* @return the pointer to the object referenced.
*/
inline T*
operator->() const throw ( Exception )
{
if ( !object ) {
throw Exception( __FILE__, __LINE__,
"reference to NULL object");
}
return object;
}
/**
* Assignment operator.
*
* @param other the Ref to assign to this one.
* @return a reference to this Ref.
* @exception Exception
*/
inline Ref<T> &
operator= ( Ref<T> other ) throw ( Exception )
{
set( other.object);
return *this;
}
/**
* Assignment operator.
*
* @param obj pointer to the object to assign to this Ref.
* @return a reference to this Ref.
* @exception Exception
*/
inline Ref<T> &
operator= ( T* obj ) throw ( Exception )
{
set( obj);
return *this;
}
/**
* Set the object referenced.
* Deletes the old referenced object is this was it's last reference.
*
* @param newobj pointer to the object to reference by this Ref.
* @exception Exception
*/
inline void
set ( T * newobj ) throw ( Exception )
{
// If equal do nothing
if ( newobj == object ) {
return;
}
// Increase reference count
if ( newobj ) {
newobj->increaseReferenceCount();
}
// Decrease the reference count of the old referable
if ( object ) {
if ( object->decreaseReferenceCount() == 0 ) {
delete object;
}
}
// Assign
object = newobj;
}
/**
* Return object pointer. This method should be used with
* care because it breaks the encapsulation.
* Typically this method is needed for the method calls
* which require literal object pointer.
*
* It may not be bad idea to pass the Ref
* objects as method arguments.
*
* @return Object pointer or NULL.
*/
inline T*
get ( void ) const throw ()
{
return object;
}
/**
* Equality operator.
*
* @param other the pointer to compare this with.
* @return true is this Ref refers to the same object as other,
* false otherwise.
*/
inline bool
operator== ( const T * other ) const throw ()
{
return object == other;
}
/**
* Equality operator.
*
* @param other the Ref to compare this with.
* @return true is the two Refs refer to the same object,
* false otherwise.
*/
inline bool
operator== ( const Ref<T> & other ) const throw ()
{
return object == other.object;
}
/**
* Unequality operator.
*
* @param other the pointer to compare this with.
* @return false is this Ref refers to a different object then other,
* true otherwise.
*/
inline bool
operator!= ( const T * other ) const throw ()
{
return object != other;
}
/**
* Unequality operator.
*
* @param other the Ref to compare this with.
* @return false is the two Refs refer to the same object,
* true otherwise.
*/
inline bool
operator!= ( const Ref<T> & other ) const throw ()
{
return object != other.object;
}
};
/* ================================================= external data structures */
/* ====================================================== function prototypes */
#endif /* REF_H */
|